2016 Severe Storm Thread

[jaxjagman]

The Rex /Omega block that was shown in East Asia is fixing to set up shop into the NW/AK with a ridge building into the Atlantic with heights rising to our east.We should be looking at severe weather threat possibly into the end of the month, first of April.

 

[Quincy]

I wouldn't even rule out a few strong to severe storms across western/Middle TN tomorrow evening, although the best forcing may be displayed somewhat farther north.

[jaxjagman]

I wouldn't even rule out a few strong to severe storms across western/Middle TN tomorrow evening, although the best forcing may be displayed somewhat farther north.

I just wish the models could get together and agree on something one day away..lol

[jaxjagman]

Lack of any sufficient moisture seems to be the problem,plenty of instability.Best threat  right now should be towards the NW Valley

 

DAY 1 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1255 AM CDT SUN MAR 27 2016

   VALID 271200Z - 281200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF THE OH
   VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS FOR MUCH OF THE OH VALLEY AND
   INTO THE LOWER TN VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE CNTRL GULF COAST AND
   SRN GA/NRN FL...

   ...SUMMARY...
   ISOLATED STRONG TO SEVERE STORMS ARE FORECAST ACROSS PARTS OF THE
   OHIO VALLEY THIS AFTERNOON/EVENING.  A LOWER-PROBABILITY RISK FOR
   SEVERE STORMS WILL EXIST ACROSS THE CENTRAL GULF COAST TO NORTH
   FLORIDA.

   ...SYNOPSIS...
   A SHORTWAVE TROUGH IS FORECAST TO MOVE FROM THE CNTRL PLAINS TO THE
   MID MS VALLEY BY 28/00Z AND TO THE LOWER GREAT LAKES BY DAYBREAK
   MONDAY.  THE NRN PORTION OF A COLD FRONT --INITIALLY OVER THE MID MS
   VALLEY EXTENDING SWWD INTO THE SRN PLAINS-- WILL PUSH EWD TO THE
   WABASH VALLEY VICINITY BY LATE AFTERNOON AS A SURFACE LOW DEEPENS AS
   IT DEVELOPS NEWD FROM THE LOWER OH VALLEY TO THE LOWER GREAT LAKES.

   ...OH VALLEY SWD INTO THE LOWER TN VALLEY...
   STRENGTHENING SLY LOW-LEVEL FLOW AHEAD OF THE APPROACHING MID-LEVEL
   WAVE WILL ADVECT 55-60 DEG F DEWPOINTS INTO THE REGION DURING THE
   DAY BENEATH A PLUME OF STEEPENING H7-H5 LAPSE RATES /7-8 DEG C PER
   KM/.  HEATING DURING THE DAY COUPLED WITH INCREASING LARGE-SCALE
   FORCING FOR ASCENT IN THE EXIT REGION OF A 70 KT H5 JET WILL WEAKEN
   THE CAP AND LEAD TO SCTD TSTM DEVELOPMENT OVER THE LOWER OH VALLEY
   BY THE LATE AFTERNOON.  STRONG EFFECTIVE SHEAR /40-50 KT/ AND
   MODERATE BUOYANCY /AROUND 1000-1500 J PER KG MLCAPE/ WILL SUPPORT
   THE DEVELOPMENT OF SUPERCELLS AND AN ISOLD LARGE-HAIL/DMGG-WIND
   THREAT.  ALTHOUGH H5 TEMPS WILL BE RELATIVELY COOL /AROUND -18 DEG
   C/...THE RELATIVELY MODEST BOUNDARY LAYER MOISTURE WILL PROBABLY
   LIMIT AN OTHERWISE HIGHER TORNADO RISK.  NONETHELESS...THE LOW RISK
   FOR A SUPERCELL TORNADO WILL LIKELY CONCENTRATE CLOSER TO THE
   SURFACE LOW AS IT DEVELOPS NEWD IN A CORRIDOR OF STRONGER LOW-LEVEL
   SHEAR /150-200 M2 PER S2 EFFECTIVE SRH/.  DIMINISHING INSTABILITY
   FARTHER NE INTO PARTS OF OH AND CNTRL/ERN KY AND UNFAVORABLE
   TIME-OF-DAY CONSIDERATIONS WILL PROBABLY LEAD TO A COINCIDENT
   WEAKENING IN STORM ACTIVITY AS IT MOVES NEWD AFTER SUNSET WITH AN
   ISOLD DMGG-WIND THREAT BECOMING THE PRIMARY CONCERN AS UPSCALE
   GROWTH OCCURS.

   ...CNTRL GULF COAST INTO SRN GA/NRN FL...
   A CLUSTER OF SHOWERS/STORMS LIKELY ONGOING SUNDAY MORNING ALONG THE
   CNTRL GULF COAST WILL LIKELY DEVELOP EWD ALONG AN EFFECTIVE BOUNDARY
   FORECAST TO MOVE INLAND.  A MARGINAL RISK FOR SEVERE STORMS MAY
   ACCOMPANY THIS EARLIER-DAY ACTIVITY.  FARTHER E...DESTABILIZATION
   DURING THE DAY AND WEAK LARGE-SCALE SUPPORT FOR ASCENT ASSOCIATED
   WITH A SRN STREAM SPEED MAX OVER THE NRN GULF MAY LEAD TO THE
   DEVELOPMENT OF A COUPLE STRONG TO SEVERE STORMS CAPABLE PRIMARILY OF
   AN ISOLD LARGE-HAIL/DMGG-WIND RISK.  THIS ACTIVITY WILL LIKELY
   WEAKEN BY THE EARLY TO MID-EVENING HOURS.

[jaxjagman]

Some good analogs showing up for the upcoming potential storm next week from CIPPS

 

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F096&rundt=2016032712&map=thbSVR

[nrgjeff]

Later this week looks positively tilted, and with bearish diurnal timing. Then most of next week is uninspiring. Hopefully the Final Four is more exciting than the weather. Week 2 includes fronts but nothing stands out. Northwest flow might work in May, but it is too early in the season now. Need a forecast change for week 2. Probably look to mid-April for the next big chance (somewhere). Western warmth is forecast to migrate east, but one still needs a new trough West/Central. 

 

RE below: I respectfully disagree with MRX on severe. Heavy rain will verify though.

[Runman292]

MRX is keeping an eye on Thursday. Here's the HWO they issued.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

A STORM SYSTEM WILL MOVE ACROSS THE TENNESSEE VALLEY AND SOUTHERN

APPALACHIANS THURSDAY. AIRMASS AHEAD OF THIS SYSTEM WILL BECOME

MOIST AND UNSTABLE WITH STRONG WINDS ALOFT. WIDESPREAD SHOWERS AND

THUNDERSTORMS WILL DEVELOP WITH DAMAGING WINDS...LARGE HAIL...AND

ISOLATED TORNADOES POSSIBLE THURSDAY AFTERNOON AND EVENING.

BESIDES THE POTENTIAL SEVERE WEATHER...LOCALIZED HEAVY RAINFALL IS

EXPECTED AS WELL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THURSDAY AFTERNOON AND EVENING.

[nrgjeff]

Thursday system has slowed down but it will do little to promote severe in the Valley. Positive tilt leads to all kinds of other problems. SPC notes trouble with low level veering ahead of the front in the Valley. Other thunderstorms in the Deep South should prevent much instability our way; and, those Deep South storms would probably cut off the already weakening LLJ. Not much of a chance for any of these issues to reverse with a positive tilt main trough. Perhaps Western Tennessee pulls off a few strong storms right on the front and in the wake of morning rain - iff midday breaks of sun. Eastern Tennessee has an additional problem, along with everything above. Midday rain would slam the door on instability regardless of what happens elsewhere.

 

Out of our immediate subforum zone, Deep South or Gulf Coast could see a few supercells Thursday if a things come together just right. Separate from the northern stream debacle, good deep layer shear is forecast in the Deep South. Low level shear is adequate, but ongoing convection will impact the LLJ. Perhaps if Tennessee rain sends an outflow boundary OFB far enough south, Deep South storms could interact with the OFB. Frankly I doubt those mesoscale details come together farther south either.

[Runman292]

Thursday system has slowed down but it will do little to promote severe in the Valley. Positive tilt leads to all kinds of other problems. SPC notes trouble with low level veering ahead of the front in the Valley. Other thunderstorms in the Deep South should prevent much instability our way; and, those Deep South storms would probably cut off the already weakening LLJ. Not much of a chance for any of these issues to reverse with a positive tilt main trough. Perhaps Western Tennessee pulls off a few strong storms right on the front and in the wake of morning rain. Eastern Tennessee has an additional problem, along with everything above. Midday rain would slam the door on instability regardless of what happens elsewhere.

Out of our immediate subforum zone, Deep South or Gulf Coast could see a few supercells Thursday if a things come together just right. Separate from the northern stream debacle, good deep layer shear is forecast in the Deep South. Low level shear is adequate, but ongoing convection will impact the LLJ. Perhaps if Tennessee rain sends an outflow boundary OFB far enough south, Deep South storms could interact with the OFB. Frankly I doubt those mesoscale details come together farther south either.

So far, it seems like we've had the strong wind shear in place, but we can't get any instability to go with it.

[rolltide_130]

So far, it seems like we've had the strong wind shear in place, but we can't get any instability to go with it.

Pretty classic hallmark of an El Niño spring, especially in the early going with the STJ influence pulling in more moisture than what would be ideal.

[nrgjeff]

Exactly! Plus right now we are in the doldrums between late winter El Nino southern severe and true spring severe. STJ giveth and taketh away, good shear in winter but too much other rain in spring. I would not get too frustrated about spring severe, still just the preseason. However for active spring severe we need the STJ to take a time-out. System digging through the Plains and ejecting this way favors severe with more instability.

[Runman292]

Exactly! Plus right now we are in the doldrums between late winter El Nino southern severe and true spring severe. STJ giveth and taketh away, good shear in winter but too much other rain in spring. I would not get too frustrated about spring severe, still just the preseason. However for active spring severe we need the STJ to take a time-out. System digging through the Plains and ejecting this way favors severe with more instability.

What I find interesting is that MRX and the local news stations are still thinking that we could see some strong to Severe storms on Thursday.

[nrgjeff]

What I find interesting is that MRX and the local news stations are still thinking that we could see some strong to Severe storms on Thursday.

 

And I am still in denial about Kansas losing, lol! Local news makes perfect sense; drum up viewers. Otherwise, it is time to accept cruel reality...

[jaxjagman]

Still some good analogs showing up.The Lawrenceburg F5 of "98" is the top analog.

 

 

 

 

 

 

[jaxjagman]

DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT WED MAR 30 2016

   VALID 311200Z - 011200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS PORTIONS MID SOUTH TO SRN
   MISSISSIPPI...

   ...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM CENTRAL GULF
   COASTAL PLAIN TO CENTRAL INDIANA...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING SLGT RISK AND
   EXTENDING INTO WRN CAROLINAS AND MUCH OF GA...

   ...SUMMARY...
   MULTIPLE ROUNDS OF SEVERE THUNDERSTORMS SHOULD MOVE ACROSS PARTS OF
   THE MID SOUTH AND LOWER MISSISSIPPI VALLEY REGIONS...POSSIBLY
   EXTENDING INTO MIDDLE TENNESSEE AND MUCH OF ALABAMA.
   TORNADOES...DAMAGING GUSTS AND LARGE HAIL ALL ARE POSSIBLE.
   SCATTERED THUNDERSTORMS ALSO SHOULD OFFER A RISK OF SEVERE WEATHER
   FARTHER NORTH OVER PARTS OF THE LOWER OHIO VALLEY REGION...PERHAPS
   AS FAR NORTH AS SOUTHERN LOWER MICHIGAN.

   ...SYNOPSIS...
   IN MID/UPPER LEVELS...HIGH-AMPLITUDE RIDGING OVER NERN PAC IS
   EXPECTED TO PROGRESS EWD/ONSHORE THIS PERIOD...WHILE
   HIGH-AMPLITUDE...SYNOPTIC-SCALE...POSITIVELY TILTED TROUGH SHIFTS
   EWD OVER CENTRAL/SWRN CONUS.  ASSOCIATED CYCLONE ALOFT -- NOW
   APPARENT IN MOISTURE-CHANNEL IMAGERY OVER MUCH OF WRN CONUS AND
   CENTERED OVER WRN UT -- IS FCST TO DEVOLVE TO POSITIVELY TILTED
   SHORTWAVE TROUGH FROM IA TO TX PANHANDLE BY START OF DAY-2
   PERIOD...31/12Z.  NRN-STREAM PERTURBATION NOW OVER NW TERRITORIES IS
   FCST TO DIG SEWD FROM NRN HIGH PLAINS ACROSS CENTRAL PLAINS THROUGH
   PERIOD...RESULTING IN ENEWD EJECTION/DEAMPLIFICATION OF LEADING
   TROUGH TO LM...IL...MO AND OK BY 1/00Z.  ITS NRN PART WILL
   ACCELERATING NEWD..RESULTING IN WEAKENING/STRETCHED 500-MB VORTICITY
   FIELD FROM SRN QUE...SERN ONT...INDIANA...AND SRN MO BY 1/12Z.
   MEANWHILE...SRN-STREAM PERTURBATION THAT SEPARATES FROM GREAT BASIN
   CYCLONE DAY-1 WILL DIG SWD/SEWD OVER AZ/NRN BAJA...THEN PIVOT EWD TO
   CHIHUAHUA...SRN NM AND ELP REGION BY 1/12Z.

   AT SFC...CYCLONE NOW STRENGTHENING OVER IML/OGA REGION IS EXPECTED
   TO WEAKEN SOMEWHAT BY START OF DAY-2 PERIOD...BECOMING ELONGATED
   AREA OF LOW PRESSURE WITH CENTERS POSSIBLE OVER IA/WI BORDER REGION
   AND INVOF MKC...BUT STRETCHED OUT ALONG COLD FRONT.  FRONT AT 31/12Z
   SHOULD EXTEND FROM NRN LOWER MI SWWD THROUGH LOW-PRESSURE AREA TO
   ERN OK...TO CENTRAL/SW TX.  BY 1/00Z FRONT SHOULD REACH SRN LOWER
   MI...SRN IL...ARKLATEX REGION...AND S-CENTRAL TX.  BY 1/12Z FRONT
   SHOULD EXTEND FROM WRN NY SWWD ACROSS TN VALLEY REGION TO PORTIONS
   TX COASTAL PLAIN.  ASIDE FROM FRONT...MOST IMPORTANT SFC PROCESSES
   WILL INVOLVE EARLY-PERIOD CONVECTION OVER DIXIE...AND
   BOUNDARIES/AIR-MASS RECOVERY BEHIND THAT.

   ...MID SOUTH/TN VALLEY TO GULF COASTAL PLAIN...
   MESSY CONVECTIVE/SVR SCENARIO IS APPARENT WITH MULTIPLE ROUNDS OF
   TSTMS POSSIBLE ACROSS OUTLOOK AREAS...MAINLY IN TWO PROCESSES...
   1. CARRYING OVER FROM DAY-1 OVERNIGHT PERIOD AND MOVING ENEWD TO
   NEWD INTO PROGRESSIVELY MORE STABLE ENVIRONMENT WITH TIME...BUT
   OFFERING SLGT-MRGL POTENTIAL FOR ALL SVR MODES BEFORE DOING SO...AND

   2. AFTN/EVENING DEVELOPMENT IN WEAK-CINH ENVIRONMENT THAT MAY OCCUR
   ALONG SFC COLD FRONT...IN WARM SECTOR CHARACTERIZED BY STG SFC
   HEATING AND RICH LOW-LEVEL MOISTURE...AND PERHAPS ALONG RESIDUAL
   BOUNDARIES LEFT BY MORNING ACTIVITY.  FOR THIS REGIME...CONSIDERABLE
   SPATIAL ADJUSTMENT STILL MAY BE NEEDED TO ACCOUNT FOR UNCERTAINTIES
   IN NEWD EXTENT OF AIR-MASS RECOVERY ACROSS MID TN/NRN AL REGION
   FOLLOWING MORNING ACTIVITY.

   IN BOTH REGIMES...SUPERCELLS WITH TORNADOES...LARGE HAIL AND
   DAMAGING GUSTS ARE POSSIBLE...ALONG WITH CLUSTERED AND QUASI-LINEAR
   MODES.  THESE TWO PROCESSES...WHILE TEMPORALLY SEPARATED...ALSO
   SPATIALLY OVERLAP OVER MUCH OF ENH-RISK AREA.  GREATEST POTENTIAL
   FOR JUXTAPOSITION OF FAVORABLE ENVIRONMENT AND SFC-BASED CONVECTION
   APPEARS TO BE OVER MS DELTA REGION AND PORTIONS MID SOUTH...WHICH
   HAVE BEEN UPGRADED TO ENH/30% BULK-SVR PROBABILITIES.  SIG-SVR
   PROBABILITIES WERE CONSIDERED AIMED MAINLY AT TORNADO
   POTENTIAL...BUT MESOSCALE UNCERTAINTIES REGARDING EARLY-PERIOD
   CONVECTION AND BOUNDARIES LAID DOWN BY THAT ACTIVITY PRECLUDED
   ASSIGNING SPECIFIC RISK AREA OF THAT SORT THIS SOON.

   DIURNAL HEATING...STG LOW-LEVEL WAA AND MOISTURE TRANSPORT BEHIND
   EARLY CONVECTION SHOULD FOSTER BOUNDARY-LAYER RECOVERY ACROSS AT
   LEAST ENH-RISK AREA...AND CONDITIONALLY FARTHER E ACROSS MID TN AND
   NRN AL.  SFC DEW POINTS SHOULD REACH MID 60S TO NEAR 70 F AT LEAST
   OVER MS/SWRN TN/WRN AL...WITH PW APCHG 1.5 INCH OVER MUCH OF MS INTO
   WRN TN...SUPPORTING AFTN MLCAPE BUILDING TO 1500-2500 J/KG RANGE.
   FCST SOUNDINGS SUGGEST 45-55-KT EFFECTIVE-SHEAR MAGNITUDES SHOULD BE
   COMMON...WITH EFFECTIVE SRH 250-350 J/KG  AND LOCALLY HIGHER.
   CONTINUED WAA SHOULD ERODE EARLY OUTFLOW AIR OVER PARTS OF MID TN
   AND AL INTO EVENING/OVERNIGHT HOURS...EXTENDING SVR THREAT EWD
   ALONG/AHEAD OF COLD FRONT.

   ...OH VALLEY TO SRN UPPER GREAT LAKES REGION...
   SVR REGIME ACROSS THIS AREA WILL BE CHARACTERIZED BY COLDER AIR
   ALOFT THAN OVER DIXIE...BUT WEAKER LOW-LEVEL THETAE AND NARROWER
   WARM SECTOR SHIFTING EWD AHEAD OF AFTN/NEAR-FRONTAL DEVELOPMENT.
   SVR POTENTIAL MAY BE WINDING DOWN EARLY IN PERIOD WITH MORNING TSTMS
   MOVING NEWD FROM END OF DAY 1 OUTLOOK AREA.  BEHIND
   THOSE...CONSIDERABLE UNCERTAINTIES REMAIN REGARDING BOTH DIABATIC
   BOUNDARY-LAYER DESTABILIZATION AND POTENTIAL TRAJECTORIES FOR
   ADVECTION OF RELATIVELY STABLE AIR OUT OF OUTFLOW FROM COMPLEXES
   FARTHER S.

   KINEMATIC ENVIRONMENT WILL FAVOR ALL SVR MODES...INCLUDING
   TORNADOES.  DEEP SHEAR AND LOW-LEVEL HODOGRAPHS EACH SHOULD ENLARGE
   WITH APCH OF EJECTING MID/UPPER-LEVEL PERTURBATION...AND MOST
   AGGRESSIVE FCST SOUNDINGS SUGGEST ENOUGH DIURNAL HEATING TO BOOST
   MLCAPE TO 100-1500 J/KG RANGE.  AS SUCH...UNCONDITIONAL 15%/SLGT
   PROBABILITIES ARE EXTENDED NWD FOR NOW...AND FURTHER
   EXPANSION/INCREASE MAY BE NEEDED DEPENDING ON WIDTH/STRENGTH OF
   WARM-SECTOR RECOVERY.

   ...SRN APPALACHIANS REGION...
   TSTMS MAY DEVELOP OVER THIS REGION DURING AFTN/EVENING...IN ADDITION
   TO POTENTIAL FOR CONVECTION FROM TN VALLEY/AL REGION TO REACH THIS
   AREA DURING LATE/OVERNIGHT HOURS.  CURVED/ENLARGED LOW-LEVEL
   HODOGRAPHS AND DEEP SHEAR EACH WILL BE FAVORABLE FOR SVR...WITH SFC
   DEW POINTS LOW-MID 60S F POTENTIALLY SUPPORTING MLCAPE 500-1000
   J/KG.  HOWEVER...GIVEN ABUNDANT CLOUDS LIKELY TO OVERSPREAD THIS
   AREA FROM SW...AND LACK OF APPARENT FOCI FOR DEEP-LAYER
   ASCENT...TIMING AND INITIATION OF CONVECTIVE POTENTIAL IS IN
   QUESTION.  FOR NOW WILL MAINTAIN MRGL UNCONDITIONAL SVR
   PROBABILITIES...GIVEN THOSE UNCERTAINTIES.

   ..EDWARDS.. 03/30/2016

[Runman292]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0100 AM CDT WED MAR 30 2016

VALID 311200Z - 011200Z

...THERE IS AN ENH RISK OF SVR TSTMS PORTIONS MID SOUTH TO SRN

MISSISSIPPI...

...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM CENTRAL GULF

COASTAL PLAIN TO CENTRAL INDIANA...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING SLGT RISK AND

EXTENDING INTO WRN CAROLINAS AND MUCH OF GA...

...SUMMARY...

MULTIPLE ROUNDS OF SEVERE THUNDERSTORMS SHOULD MOVE ACROSS PARTS OF

THE MID SOUTH AND LOWER MISSISSIPPI VALLEY REGIONS...POSSIBLY

EXTENDING INTO MIDDLE TENNESSEE AND MUCH OF ALABAMA.

TORNADOES...DAMAGING GUSTS AND LARGE HAIL ALL ARE POSSIBLE.

SCATTERED THUNDERSTORMS ALSO SHOULD OFFER A RISK OF SEVERE WEATHER

FARTHER NORTH OVER PARTS OF THE LOWER OHIO VALLEY REGION...PERHAPS

AS FAR NORTH AS SOUTHERN LOWER MICHIGAN.

...SYNOPSIS...

IN MID/UPPER LEVELS...HIGH-AMPLITUDE RIDGING OVER NERN PAC IS

EXPECTED TO PROGRESS EWD/ONSHORE THIS PERIOD...WHILE

HIGH-AMPLITUDE...SYNOPTIC-SCALE...POSITIVELY TILTED TROUGH SHIFTS

EWD OVER CENTRAL/SWRN CONUS. ASSOCIATED CYCLONE ALOFT -- NOW

APPARENT IN MOISTURE-CHANNEL IMAGERY OVER MUCH OF WRN CONUS AND

CENTERED OVER WRN UT -- IS FCST TO DEVOLVE TO POSITIVELY TILTED

SHORTWAVE TROUGH FROM IA TO TX PANHANDLE BY START OF DAY-2

PERIOD...31/12Z. NRN-STREAM PERTURBATION NOW OVER NW TERRITORIES IS

FCST TO DIG SEWD FROM NRN HIGH PLAINS ACROSS CENTRAL PLAINS THROUGH

PERIOD...RESULTING IN ENEWD EJECTION/DEAMPLIFICATION OF LEADING

TROUGH TO LM...IL...MO AND OK BY 1/00Z. ITS NRN PART WILL

ACCELERATING NEWD..RESULTING IN WEAKENING/STRETCHED 500-MB VORTICITY

FIELD FROM SRN QUE...SERN ONT...INDIANA...AND SRN MO BY 1/12Z.

MEANWHILE...SRN-STREAM PERTURBATION THAT SEPARATES FROM GREAT BASIN

CYCLONE DAY-1 WILL DIG SWD/SEWD OVER AZ/NRN BAJA...THEN PIVOT EWD TO

CHIHUAHUA...SRN NM AND ELP REGION BY 1/12Z.

AT SFC...CYCLONE NOW STRENGTHENING OVER IML/OGA REGION IS EXPECTED

TO WEAKEN SOMEWHAT BY START OF DAY-2 PERIOD...BECOMING ELONGATED

AREA OF LOW PRESSURE WITH CENTERS POSSIBLE OVER IA/WI BORDER REGION

AND INVOF MKC...BUT STRETCHED OUT ALONG COLD FRONT. FRONT AT 31/12Z

SHOULD EXTEND FROM NRN LOWER MI SWWD THROUGH LOW-PRESSURE AREA TO

ERN OK...TO CENTRAL/SW TX. BY 1/00Z FRONT SHOULD REACH SRN LOWER

MI...SRN IL...ARKLATEX REGION...AND S-CENTRAL TX. BY 1/12Z FRONT

SHOULD EXTEND FROM WRN NY SWWD ACROSS TN VALLEY REGION TO PORTIONS

TX COASTAL PLAIN. ASIDE FROM FRONT...MOST IMPORTANT SFC PROCESSES

WILL INVOLVE EARLY-PERIOD CONVECTION OVER DIXIE...AND

BOUNDARIES/AIR-MASS RECOVERY BEHIND THAT.

...MID SOUTH/TN VALLEY TO GULF COASTAL PLAIN...

MESSY CONVECTIVE/SVR SCENARIO IS APPARENT WITH MULTIPLE ROUNDS OF

TSTMS POSSIBLE ACROSS OUTLOOK AREAS...MAINLY IN TWO PROCESSES...

1. CARRYING OVER FROM DAY-1 OVERNIGHT PERIOD AND MOVING ENEWD TO

NEWD INTO PROGRESSIVELY MORE STABLE ENVIRONMENT WITH TIME...BUT

OFFERING SLGT-MRGL POTENTIAL FOR ALL SVR MODES BEFORE DOING SO...AND

2. AFTN/EVENING DEVELOPMENT IN WEAK-CINH ENVIRONMENT THAT MAY OCCUR

ALONG SFC COLD FRONT...IN WARM SECTOR CHARACTERIZED BY STG SFC

HEATING AND RICH LOW-LEVEL MOISTURE...AND PERHAPS ALONG RESIDUAL

BOUNDARIES LEFT BY MORNING ACTIVITY. FOR THIS REGIME...CONSIDERABLE

SPATIAL ADJUSTMENT STILL MAY BE NEEDED TO ACCOUNT FOR UNCERTAINTIES

IN NEWD EXTENT OF AIR-MASS RECOVERY ACROSS MID TN/NRN AL REGION

FOLLOWING MORNING ACTIVITY.

IN BOTH REGIMES...SUPERCELLS WITH TORNADOES...LARGE HAIL AND

DAMAGING GUSTS ARE POSSIBLE...ALONG WITH CLUSTERED AND QUASI-LINEAR

MODES. THESE TWO PROCESSES...WHILE TEMPORALLY SEPARATED...ALSO

SPATIALLY OVERLAP OVER MUCH OF ENH-RISK AREA. GREATEST POTENTIAL

FOR JUXTAPOSITION OF FAVORABLE ENVIRONMENT AND SFC-BASED CONVECTION

APPEARS TO BE OVER MS DELTA REGION AND PORTIONS MID SOUTH...WHICH

HAVE BEEN UPGRADED TO ENH/30% BULK-SVR PROBABILITIES. SIG-SVR

PROBABILITIES WERE CONSIDERED AIMED MAINLY AT TORNADO

POTENTIAL...BUT MESOSCALE UNCERTAINTIES REGARDING EARLY-PERIOD

CONVECTION AND BOUNDARIES LAID DOWN BY THAT ACTIVITY PRECLUDED

ASSIGNING SPECIFIC RISK AREA OF THAT SORT THIS SOON.

DIURNAL HEATING...STG LOW-LEVEL WAA AND MOISTURE TRANSPORT BEHIND

EARLY CONVECTION SHOULD FOSTER BOUNDARY-LAYER RECOVERY ACROSS AT

LEAST ENH-RISK AREA...AND CONDITIONALLY FARTHER E ACROSS MID TN AND

NRN AL. SFC DEW POINTS SHOULD REACH MID 60S TO NEAR 70 F AT LEAST

OVER MS/SWRN TN/WRN AL...WITH PW APCHG 1.5 INCH OVER MUCH OF MS INTO

WRN TN...SUPPORTING AFTN MLCAPE BUILDING TO 1500-2500 J/KG RANGE.

FCST SOUNDINGS SUGGEST 45-55-KT EFFECTIVE-SHEAR MAGNITUDES SHOULD BE

COMMON...WITH EFFECTIVE SRH 250-350 J/KG AND LOCALLY HIGHER.

CONTINUED WAA SHOULD ERODE EARLY OUTFLOW AIR OVER PARTS OF MID TN

AND AL INTO EVENING/OVERNIGHT HOURS...EXTENDING SVR THREAT EWD

ALONG/AHEAD OF COLD FRONT.

...OH VALLEY TO SRN UPPER GREAT LAKES REGION...

SVR REGIME ACROSS THIS AREA WILL BE CHARACTERIZED BY COLDER AIR

ALOFT THAN OVER DIXIE...BUT WEAKER LOW-LEVEL THETAE AND NARROWER

WARM SECTOR SHIFTING EWD AHEAD OF AFTN/NEAR-FRONTAL DEVELOPMENT.

SVR POTENTIAL MAY BE WINDING DOWN EARLY IN PERIOD WITH MORNING TSTMS

MOVING NEWD FROM END OF DAY 1 OUTLOOK AREA. BEHIND

THOSE...CONSIDERABLE UNCERTAINTIES REMAIN REGARDING BOTH DIABATIC

BOUNDARY-LAYER DESTABILIZATION AND POTENTIAL TRAJECTORIES FOR

ADVECTION OF RELATIVELY STABLE AIR OUT OF OUTFLOW FROM COMPLEXES

FARTHER S.

KINEMATIC ENVIRONMENT WILL FAVOR ALL SVR MODES...INCLUDING

TORNADOES. DEEP SHEAR AND LOW-LEVEL HODOGRAPHS EACH SHOULD ENLARGE

WITH APCH OF EJECTING MID/UPPER-LEVEL PERTURBATION...AND MOST

AGGRESSIVE FCST SOUNDINGS SUGGEST ENOUGH DIURNAL HEATING TO BOOST

MLCAPE TO 100-1500 J/KG RANGE. AS SUCH...UNCONDITIONAL 15%/SLGT

PROBABILITIES ARE EXTENDED NWD FOR NOW...AND FURTHER

EXPANSION/INCREASE MAY BE NEEDED DEPENDING ON WIDTH/STRENGTH OF

WARM-SECTOR RECOVERY.

...SRN APPALACHIANS REGION...

TSTMS MAY DEVELOP OVER THIS REGION DURING AFTN/EVENING...IN ADDITION

TO POTENTIAL FOR CONVECTION FROM TN VALLEY/AL REGION TO REACH THIS

AREA DURING LATE/OVERNIGHT HOURS. CURVED/ENLARGED LOW-LEVEL

HODOGRAPHS AND DEEP SHEAR EACH WILL BE FAVORABLE FOR SVR...WITH SFC

DEW POINTS LOW-MID 60S F POTENTIALLY SUPPORTING MLCAPE 500-1000

J/KG. HOWEVER...GIVEN ABUNDANT CLOUDS LIKELY TO OVERSPREAD THIS

AREA FROM SW...AND LACK OF APPARENT FOCI FOR DEEP-LAYER

ASCENT...TIMING AND INITIATION OF CONVECTIVE POTENTIAL IS IN

QUESTION. FOR NOW WILL MAINTAIN MRGL UNCONDITIONAL SVR

PROBABILITIES...GIVEN THOSE UNCERTAINTIES.

..EDWARDS.. 03/30/2016

Wow, could we actually see a Severe threat that finally happens? I'm interested in that last part about East TN. It sounds like they would like to include us in the Slight risk, but some uncertainties are keeping them from going higher than marginal.

[jaxjagman]

 

DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT WED MAR 30 2016

   VALID 311200Z - 011200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PORTIONS MUCH OF
   MS...FAR NE LA/SE AR...W TN/KY...SE IL AND SW IND...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DEEP SOUTH TO LAKE
   MICHIGAN...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE NORTHERN GULF COAST TO
   THE MIDWEST AND PORTIONS OF THE CAROLINAS...

   ...SUMMARY...
   MULTIPLE ROUNDS OF SEVERE THUNDERSTORMS ARE EXPECTED FROM THE LOWER
   MISSISSIPPI VALLEY NORTH AND EAST TO THE MIDDLE MISSISSIPPI AND OHIO
   VALLEYS INTO THE DEEP SOUTH ON THURSDAY. TORNADOES...VERY LARGE HAIL
   AND DAMAGING WINDS ALL WILL BE POSSIBLE.

   ...SYNOPSIS...

   MULTIFACETED THREAT WILL UNFOLD ON THURSDAY. STRONG VERTICAL SHEAR
   ASSOCIATED WITH LARGER-SCALE UPPER TROUGH WILL COINCIDE WITH
   EXPANDING WARM SECTOR FROM THE GULF COAST TO THE MID-MS/OH VALLEY
   REGION. SPORADIC SEVERE WILL LIKELY BE ONGOING DURING THE MORNING
   ACROSS PARTS OF THE LOWER MS VALLEY WITH BROADER AREA OF
   SHOWERS/THUNDERSTORMS FROM LOWER MI S/SW TO THE MID/LOWER MS VALLEY.
   THIS ACTIVITY SHOULD DIMINISH/SHIFT E/NE TO NEAR OH THROUGH THE
   WESTERN TN VALLEY BY 18Z. AS A RESULT...RECOVERY ACROSS THE WARM
   SECTOR APPEARS LIKELY. A SECOND ROUND OF SEVERE THUNDERSTORMS SHOULD
   THEN EVOLVE ALONG THE SOUTHEASTWARD ADVANCING COLD FRONT DURING THE
   LATE AFTERNOON INTO THE OVERNIGHT HOURS FROM NEAR LAKE MICHIGAN
   SOUTHWARD THROUGH THE DEEP SOUTH.

   ...LOWER MS AND TN VALLEYS REGION...

   AREAS OF SCATTERED THUNDERSTORM CLUSTERS AND BOWING LINE SEGMENTS
   WILL LIKELY BE PRODUCING AT LEAST ISOLATED SEVERE AT THE BEGINNING
   OF THE PERIOD. ALL HAZARD TYPES WILL BE POSSIBLE WITH THIS INITIAL
   ACTIVITY...THOUGH LARGE HAIL IS THE MAIN CONCERN AS STORMS COULD BE
   SLIGHTLY ELEVATED. ANY STORMS THAT ARE SURFACE BASED HOWEVER WILL
   HAVE AN ACCOMPANYING STRONG WIND AND TORNADO THREAT. THIS ACTIVITY
   SHOULD MIGRATE NORTHEAST AND DIMINISH DURING THE MORNING...WHILE
   LEAVING AN OUTFLOW BOUNDARY AND COLD POOL ACROSS PARTS OF THE
   ARKLAMISS REGION. STRONG WARM ADVECTION REGIME AND AT LEAST MODEST
   SURFACE HEATING  SHOULD ALLOW FOR AIRMASS RECOVERY BY THE
   AFTERNOON...THOUGH THERE COULD BE POCKETS WHERE RECOVERY IS POOR IN
   A RELATIVE SENSE...LEADING TO GAPS IN HIGHER PROBABILITY SEVERE.
   UNCERTAINTY IN WHERE THIS MAY OCCUR WILL NEGATE ANY SEPARATION IN
   ENHANCED PROBABILITY AREA. ADDITIONAL UNCERTAINTY EXISTS WITH
   REGARDS TO STORM COVERAGE GIVEN STRONGER FORCING FOR ASCENT WILL BE
   FOCUSED MORE OVER THE MID-MS/OH VALLEY REGION.

   MID TO UPPER 60S DEWPOINTS COUPLED WITH MODERATE INSTABILITY...STEEP
   LAPSE RATES AND STRONG LOW TO MID-LEVEL SHEAR WILL SUPPORT
   SUPERCELLS CAPABLE OF TORNADOES...LARGE HAIL AND DAMAGING WINDS.
   GIVEN THERMODYNAMIC AND KINEMATIC PARAMETER SPACE...SIG SEVERE
   POTENTIAL EXISTS WITH VERY LARGE HAIL AND PERHAPS A STRONG TORNADO
   OR TWO POSSIBLE. DURING THE NIGHT AS A SWLY LLJ INCREASES...STORMS
   MAY CONCEAL INTO AN EASTWARD PROPAGATING BOW/MCS...IMPACTING
   PORTIONS OF AL...MIDDLE/WRN TN AND INTO GA.

   ...MID-MS AND LOWER OH VALLEY REGION...

   ONGOING CONVECTION AT THE BEGINNING OF THE PERIOD WILL SHIFT
   NORTHEAST TOWARD THE MID/UPPER OH VALLEY AND APPALACHIANS BY MIDDAY.
   GIVEN STRONG SOUTH/SOUTHWESTERLY DEEP LAYER FLOW...MOISTURE WILL
   QUICKLY STREAM NORTHWARD AND HEATING IN THE WAKE OF MORNING
   CONVECTION WILL RESULT IN STRONG DESTABILIZATION WITH SBCAPE VALUES
   APPROACHING 1000 J/KG AS FAR NORTH AND NORTHERN IL/IND INTO FAR SW
   LOWER MI. FURTHER SOUTH ACROSS PARTS OF SOUTHERN IL...AND ADJACENT
   PORTIONS OF THE LOWER OH VALLEY...BETTER MOISTURE WILL RESULT IN
   HIGHER CAPE VALUES...APPROACHING 2500 J/KG. THUNDERSTORMS ARE
   EXPECTED TO DEVELOP ALONG THE SOUTHEASTWARD ADVANCING COLD FRONT
   NEAR THE SFC LOW OVER NRN INTO CNTRL IL BY MID-AFTERNOON AND
   INCREASE IN COVERAGE/INTENSITY WITH SOUTHERN AND EASTERN EXTENT INTO
   PARTS OF SE IL/SW IND/W KY/FAR SE MO. SUPERCELLS WITH ALL SEVERE
   HAZARDS WILL BE POSSIBLE ACROSS THE SLIGHT RISK AREA WITH LARGE HAIL
   BEING THE PRIMARY CONCERN. ACROSS THE ENHANCED RISK AREA...SIG HAIL
   AND A FEW TORNADOES /POTENTIALLY STRONG/ ARE POSSIBLE. THIS ACTIVITY
   SHOULD GROW UPSCALE INTO BOWING SEGMENTS WITH EASTWARD EXTENT
   OVERNIGHT FROM CENTRAL IND/KY INTO OH AND THE APPALACHIANS BY THE
   END OF THE PERIOD.

   ..LEITMAN.. 03/30/2016

[Runman292]

Storm Prediction Center Mar 30 2016 1730 UTC Day 2 Convective Outlook.png

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1230 PM CDT WED MAR 30 2016

VALID 311200Z - 011200Z

...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PORTIONS MUCH OF

MS...FAR NE LA/SE AR...W TN/KY...SE IL AND SW IND...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DEEP SOUTH TO LAKE

MICHIGAN...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE NORTHERN GULF COAST TO

THE MIDWEST AND PORTIONS OF THE CAROLINAS...

...SUMMARY...

MULTIPLE ROUNDS OF SEVERE THUNDERSTORMS ARE EXPECTED FROM THE LOWER

MISSISSIPPI VALLEY NORTH AND EAST TO THE MIDDLE MISSISSIPPI AND OHIO

VALLEYS INTO THE DEEP SOUTH ON THURSDAY. TORNADOES...VERY LARGE HAIL

AND DAMAGING WINDS ALL WILL BE POSSIBLE.

...SYNOPSIS...

MULTIFACETED THREAT WILL UNFOLD ON THURSDAY. STRONG VERTICAL SHEAR

ASSOCIATED WITH LARGER-SCALE UPPER TROUGH WILL COINCIDE WITH

EXPANDING WARM SECTOR FROM THE GULF COAST TO THE MID-MS/OH VALLEY

REGION. SPORADIC SEVERE WILL LIKELY BE ONGOING DURING THE MORNING

ACROSS PARTS OF THE LOWER MS VALLEY WITH BROADER AREA OF

SHOWERS/THUNDERSTORMS FROM LOWER MI S/SW TO THE MID/LOWER MS VALLEY.

THIS ACTIVITY SHOULD DIMINISH/SHIFT E/NE TO NEAR OH THROUGH THE

WESTERN TN VALLEY BY 18Z. AS A RESULT...RECOVERY ACROSS THE WARM

SECTOR APPEARS LIKELY. A SECOND ROUND OF SEVERE THUNDERSTORMS SHOULD

THEN EVOLVE ALONG THE SOUTHEASTWARD ADVANCING COLD FRONT DURING THE

LATE AFTERNOON INTO THE OVERNIGHT HOURS FROM NEAR LAKE MICHIGAN

SOUTHWARD THROUGH THE DEEP SOUTH.

...LOWER MS AND TN VALLEYS REGION...

AREAS OF SCATTERED THUNDERSTORM CLUSTERS AND BOWING LINE SEGMENTS

WILL LIKELY BE PRODUCING AT LEAST ISOLATED SEVERE AT THE BEGINNING

OF THE PERIOD. ALL HAZARD TYPES WILL BE POSSIBLE WITH THIS INITIAL

ACTIVITY...THOUGH LARGE HAIL IS THE MAIN CONCERN AS STORMS COULD BE

SLIGHTLY ELEVATED. ANY STORMS THAT ARE SURFACE BASED HOWEVER WILL

HAVE AN ACCOMPANYING STRONG WIND AND TORNADO THREAT. THIS ACTIVITY

SHOULD MIGRATE NORTHEAST AND DIMINISH DURING THE MORNING...WHILE

LEAVING AN OUTFLOW BOUNDARY AND COLD POOL ACROSS PARTS OF THE

ARKLAMISS REGION. STRONG WARM ADVECTION REGIME AND AT LEAST MODEST

SURFACE HEATING SHOULD ALLOW FOR AIRMASS RECOVERY BY THE

AFTERNOON...THOUGH THERE COULD BE POCKETS WHERE RECOVERY IS POOR IN

A RELATIVE SENSE...LEADING TO GAPS IN HIGHER PROBABILITY SEVERE.

UNCERTAINTY IN WHERE THIS MAY OCCUR WILL NEGATE ANY SEPARATION IN

ENHANCED PROBABILITY AREA. ADDITIONAL UNCERTAINTY EXISTS WITH

REGARDS TO STORM COVERAGE GIVEN STRONGER FORCING FOR ASCENT WILL BE

FOCUSED MORE OVER THE MID-MS/OH VALLEY REGION.

MID TO UPPER 60S DEWPOINTS COUPLED WITH MODERATE INSTABILITY...STEEP

LAPSE RATES AND STRONG LOW TO MID-LEVEL SHEAR WILL SUPPORT

SUPERCELLS CAPABLE OF TORNADOES...LARGE HAIL AND DAMAGING WINDS.

GIVEN THERMODYNAMIC AND KINEMATIC PARAMETER SPACE...SIG SEVERE

POTENTIAL EXISTS WITH VERY LARGE HAIL AND PERHAPS A STRONG TORNADO

OR TWO POSSIBLE. DURING THE NIGHT AS A SWLY LLJ INCREASES...STORMS

MAY CONCEAL INTO AN EASTWARD PROPAGATING BOW/MCS...IMPACTING

PORTIONS OF AL...MIDDLE/WRN TN AND INTO GA.

...MID-MS AND LOWER OH VALLEY REGION...

ONGOING CONVECTION AT THE BEGINNING OF THE PERIOD WILL SHIFT

NORTHEAST TOWARD THE MID/UPPER OH VALLEY AND APPALACHIANS BY MIDDAY.

GIVEN STRONG SOUTH/SOUTHWESTERLY DEEP LAYER FLOW...MOISTURE WILL

QUICKLY STREAM NORTHWARD AND HEATING IN THE WAKE OF MORNING

CONVECTION WILL RESULT IN STRONG DESTABILIZATION WITH SBCAPE VALUES

APPROACHING 1000 J/KG AS FAR NORTH AND NORTHERN IL/IND INTO FAR SW

LOWER MI. FURTHER SOUTH ACROSS PARTS OF SOUTHERN IL...AND ADJACENT

PORTIONS OF THE LOWER OH VALLEY...BETTER MOISTURE WILL RESULT IN

HIGHER CAPE VALUES...APPROACHING 2500 J/KG. THUNDERSTORMS ARE

EXPECTED TO DEVELOP ALONG THE SOUTHEASTWARD ADVANCING COLD FRONT

NEAR THE SFC LOW OVER NRN INTO CNTRL IL BY MID-AFTERNOON AND

INCREASE IN COVERAGE/INTENSITY WITH SOUTHERN AND EASTERN EXTENT INTO

PARTS OF SE IL/SW IND/W KY/FAR SE MO. SUPERCELLS WITH ALL SEVERE

HAZARDS WILL BE POSSIBLE ACROSS THE SLIGHT RISK AREA WITH LARGE HAIL

BEING THE PRIMARY CONCERN. ACROSS THE ENHANCED RISK AREA...SIG HAIL

AND A FEW TORNADOES /POTENTIALLY STRONG/ ARE POSSIBLE. THIS ACTIVITY

SHOULD GROW UPSCALE INTO BOWING SEGMENTS WITH EASTWARD EXTENT

OVERNIGHT FROM CENTRAL IND/KY INTO OH AND THE APPALACHIANS BY THE

END OF THE PERIOD.

..LEITMAN.. 03/30/2016

The threat appears to be expanding. It looks like it's going to be a waiting game in our neck of the woods to see if that first band of rain can move through quick enough and the airmass can recover.

[tnweathernut]

The threat appears to be expanding. It looks like it's going to be a waiting game in our neck of the woods to see if that first band of rain can move through quick enough and the airmass can recover.

For most of east TN, and in the words of Dumb and Dumber.............. "so you're telling me there's a chance"..?

 

This has no-go written all over it for most areas east of the plateau. 

[Runman292]

For most of east TN, and in the words of Dumb and Dumber.............. "so you're telling me there's a chance"..?

This has no-go written all over it for most areas east of the plateau.

Think of it like this:

There was no risk for Severe storms yesterday according to the SPC. Now, there's a marginal risk.

Just crossing my fingers here, lol.

[tnweathernut]

Think of it like this:

There was no risk for Severe storms yesterday according to the SPC. Now, there's a marginal risk.

Just crossing my fingers here, lol.

I don't like or want severe.  I know I am in the minority, but the property damage associated with past storms has cost me tens of thousands of dollars (I own an insurance agency).  I am in awe of severe storms, but can certainly do without loss of property and of course...........life......

[Runman292]

I don't like or want severe. I know I am in the minority, but the property damage associated with past storms has cost me tens of thousands of dollars (I own an insurance agency). I am in awe of severe storms, but can certainly do without loss of property and of course...........life......

I'm not exactly in favor of property damage or loss of life either. I do however enjoy observing storms in person.

[nrgjeff]

Parameters are strong western half iff clearing for a few hours. NAM has a habit of amping up CAPE which ends up performing like KU shooting - sorry one last gripe. Eastern third of our sub-forum looks safe from convective severe. Mountain wave winds may be a different story. Middle third is classic conditional slight. Western third probably will clear out for at least a short time. ENH will require some true destabilization, which will depend on how many hours of heating between lines. If the temps/instability verify, an outflow boundary from morning rain will be lurking (west) ...

[Runman292]

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0102 AM CDT THU MAR 31 2016

VALID 311200Z - 011200Z

...THERE IS AN ENH RISK OF SVR TSTMS ACROSS MUCH OF NRN MS AND

AL...TN...SWRN KY...FAR ERN AR AND NERN LA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL GULF COAST NWD

ACROSS THE OH VALLEY...

...THERE IS A MRGL RISK OF SVR TSTMS FROM LOWER MI SWD TO THE GULF

OF MEXICO...

...SUMMARY...

SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS A LARGE AREA EXTENDING FROM

THE CENTRAL GULF COAST STATES NORTHWARD ACROSS THE OHIO VALLEY TO

SOUTHERN MICHIGAN. THE GREATEST THREAT OF TORNADOES AND VERY LARGE

HAIL WILL BE CENTERED OVER NORTHERN MISSISSIPPI AND ALABAMA INTO

TENNESSEE AND SOUTHERN KENTUCKY. MORE ISOLATED SEVERE STORMS ARE

POSSIBLE DURING THE EVENING INTO THE WESTERN CAROLINAS...AND FRIDAY

MORNING ALONG THE CENTRAL GULF COAST.

...SYNOPSIS...

A BROAD BELT OF SWLY FLOW ALOFT WILL STRETCH FROM NRN MEXICO ACROSS

MUCH OF THE ERN STATES WITH LEADING SHORTWAVE TROUGH AND ASSOCIATED

100 KT MIDLEVEL SPEED MAX MOVING FROM THE MID MS VALLEY INTO THE

GREAT LAKES. A SECONDARY UPPER LEVEL JET WILL ALSO BE PRESENT

FARTHER S FROM TX ACROSS THE CNTRL GULF COAST. AT THE SURFACE...LOW

PRESSURE WILL MOVE FROM NRN IL INTO LOWER MI WITH A STALLING FRONT

EXTENDING SWWD ACROSS IL AND INTO ERN TX BY LATE AFTERNOON.

AHEAD OF THIS FRONT...STRONG SLY LOW-LEVEL FLOW WILL MAINTAIN A NWD

FLUX OF MOISTURE WITH 60 F DEWPOINTS TO THE OH RIVER...AND MID TO

UPPER 60S F TO THE S. THE COMBINATION OF A VERY MOIST AND UNSTABLE

AIR MASS WITH COOL TEMPERATURES ALOFT...ALONG WITH AMPLE DEEP-LAYER

SHEAR WILL BE PRESENT OVER A LARGE AREA AND WILL SUPPORT SEVERE

STORMS. HOWEVER...THE FORECAST IS RELATIVELY COMPLEX OWING TO EARLY

DAY RAIN AND STORMS...AS WELL AS SUBTLE FORCING FOR ASCENT

ESPECIALLY ACROSS SRN AREAS. THAT SAID...A CONDITIONAL THREAT OF

VERY LARGE HAIL AND PERHAPS A COUPLE STRONG TORNADOES DOES EXIST

DURING THE AFTERNOON AND EVENING OVER THE ENHANCED RISK AREA...WITH

MORE OF AN ISOLATED RISK PERIPHERALLY.

...SRN AND ERN IL...IND...KY...

A BROKEN LINE OF STORMS IS EXPECTED TO FORM RELATIVELY EARLY IN THE

DAY...BY AROUND 18Z...FROM THE SFC LOW IN NRN IL SWD TO THE OH

RIVER. WIND FIELDS WILL BE EXTREMELY STRONG WITH OVER 50 KTS AT 700

MB. ONLY MARGINAL LOW-LEVEL SRH VALUES ARE EXPECTED TO BE PRESENT

OWING TO VEERING WINDS WITH TIME...HOWEVER...LOW-LEVEL BUOYANCY

SHOULD BE SUFFICIENT FOR SCATTERED SEVERE STORMS WITH LONG

HODOGRAPHS SUPPORTING HAIL. AN ISOLATED TORNADO CANNOT BE RULED OUT

GIVEN FAVORABLE CELLULAR STORM MODE AS WELL...BUT FAST-MOVING

SPLITTING CELLS SEEM PROBABLE. A FEW DAMAGING WIND GUSTS ARE ALSO

EXPECTED GIVEN VERY FAST STORM MOTIONS AND OUTFLOW.

...ERN AR/NRN LA EWD ACROSS TN...CNTRL AND NRN MS/AL...SRN

APPALACHIANS...

A COMPLICATED FORECAST SCENARIO WILL UNFOLD TODAY...BEGINNING WITH A

BATCH OF RAIN AND STORMS EARLY IN THE MORNING ACROSS MUCH OF NRN MS

AND WRN AL. THIS ACTIVITY IS EXPECTED TO SHIFT EWD DURING THE DAY

OVER AL AND NRN GA....SUPPORTED BY DIURNAL DESTABILIZATION AND A

STRONG SWLY LOW-LEVEL JET. THUS...SOME OF THIS ACTIVITY MAY BECOME

SEVERE WITH DAMAGING WINDS AND/OR AN ISOLATED TORNADO THREAT.

IN THE WAKE OF THIS ACTIVITY...STRONG HEATING WILL OCCUR OVER THE

MID TO LOWER MS VALLEY REGION. THE COLD FRONT WILL BECOME NEARLY

STATIONARY...ALLOWING FOR FULL HEATING AND A DEEPENING MOIST

BOUNDARY LAYER WHICH WILL LEAD TO AREAS OF STRONG INSTABILITY AND

LITTLE INHIBITION. FORECAST SOUNDINGS INDICATE AN ELEVATED MIXED

LAYER WITH 7.5 TO 8.0 C/KM 700-500 MB LAPSE RATES. COUPLED WITH A

VEERING WIND PROFILE WITH HEIGHT...THIS SHOULD SET THE STAGE FOR

ROBUST SUPERCELL POTENTIAL INCLUDING VERY LARGE DAMAGING HAIL AND

TORNADOES. STORM INITIATION WILL LIKELY BE ALONG THE FRONT IN THE

18-20Z TIME FRAME FROM WRN TN/ERN AR INTO THE SABINE RIVER

VALLEY...WITH STORMS DEVELOPING ENEWD WITH TIME. OF SPECIAL INTEREST

IS ANY OUTFLOW BOUNDARY FROM EARLY DAY STORMS. SUCH AN AREA WOULD

LIKELY HARBOR ENHANCED LOW-LEVEL SHEAR AND MAY SUPPORT STRONG

TORNADOES BY LATE AFTERNOON AND INTO THE EVENING WITH THE AREA OF

GREATEST CONCERN INCLUDING NRN MS...NRN AL...AND SRN TN.

[Chinook]

I think the 10% tornado zone on this outlook in MS, AL, and TN could really get a lot of severe weather reports tomorrow. Unfortunately this part of the south got hit hard on Dec. 23rd. Also, night-time tornadoes are always worse, because people aren't ready.

[Runman292]

The key to this system is cloud cover. If clearing happens earlier than expected, then the severe threat increases. If it happens later, then it decreases.

[jaxjagman]

Meso models have showing S/TN and N/AL..N/MS this area getting hit the last couple days and not backing down

[nrgjeff]

Low and behold a massive midday rain shield is in progress! Anybody surprised? Gosh I hope not; it was well progged by models for North Alabama, Middle and Eastern Tenn. Look for the ENH to get whittled southwest away from Chatty. Keep Slight for possible wind later in CHA. Slight is tough to justify in Knox but overnight I could see the mountain wave pattern helping promote some hybrid wave/convection wind. Nashville is pretty stable now but clearing is closing in. BNA should be too veered for tornadoes but could get some wind from the later line of storms.

 

Outflow boundary has settled well into Mississippi and Alabama so I bet against Tennessee tornadoes. Despite south winds currently, Tennessee surface should veer off slightly this afternoon. Also Tennessee is starting off stable after rain. Memphis may see some hail and wind with new thunderstorms but ongoing other junk reduces the tornado threat there. North Alabama could see wind this evening.

 

Alright we do have a chase target despite all the troubles north of the outflow boundary OFB. Mississippi should become unstable this afternoon and the OFB should gradually lift north. OFB will be a moving target, but I believe an good place to start. Latest HRRR is waffling a bit on storm mode but pattern recognition is clear. Target the OFB intersection with a pre-frontal trough forecast in Mississippi. Upper level winds will strengthen late this afternoon. Low level shear will be locally favorable on the OFB. I would chase the cell on the OFB trough intersection or perhaps 1-2 cells east if they have better inflow.

[Runman292]

Low and behold a massive midday rain shield is in progress! Anybody surprised? Gosh I hope not; it was well progged by models for North Alabama, Middle and Eastern Tenn. Look for the ENH to get whittled southwest away from Chatty. Keep Slight for possible wind later in CHA. Slight is tough to justify in Knox but overnight I could see the mountain wave pattern helping promote some hybrid wave/convection wind. Nashville is pretty stable now but clearing is closing in. BNA should be too veered for tornadoes but could get some nice wind from the later line of storms.

Outflow boundary has settled well into Mississippi and Alabama so I bet against Tennessee tornadoes. Despite south winds currently, Tennessee surface should veer off slightly this afternoon. Also Tennessee is starting off stable after rain. Memphis may see some hail and wind with new thunderstorms but ongoing other junk reduces the tornado threat there. North Alabama could see good wind this evening.

Alright we do have a chase target despite all the troubles north of the outflow boundary OFB. Mississippi should become unstable this afternoon and the OFB should gradually lift north. OFB will be a moving target, but I believe an good place to start. Latest HRRR is waffling a bit on storm mode but pattern recognition is clear. Target the OFB intersection with a pre-frontal trough forecast in Mississippi. Upper level winds will strengthen late this afternoon. Low level shear will be locally favorable on the OFB. I would chase the cell on the OFB trough intersection or perhaps 1-2 cells east if they have better inflow.

The rain shield appears to be decaying, IMO. There was a lot more rain when it was in West Tennessee.

[PowellVolz]

Low and behold a massive midday rain shield is in progress! Anybody surprised? Gosh I hope not; it was well progged by models for North Alabama, Middle and Eastern Tenn. Look for the ENH to get whittled southwest away from Chatty. Keep Slight for possible wind later in CHA. Slight is tough to justify in Knox but overnight I could see the mountain wave pattern helping promote some hybrid wave/convection wind. Nashville is pretty stable now but clearing is closing in. BNA should be too veered for tornadoes but could get some wind from the later line of storms.

Outflow boundary has settled well into Mississippi and Alabama so I bet against Tennessee tornadoes. Despite south winds currently, Tennessee surface should veer off slightly this afternoon. Also Tennessee is starting off stable after rain. Memphis may see some hail and wind with new thunderstorms but ongoing other junk reduces the tornado threat there. North Alabama could see wind this evening.

Alright we do have a chase target despite all the troubles north of the outflow boundary OFB. Mississippi should become unstable this afternoon and the OFB should gradually lift north. OFB will be a moving target, but I believe an good place to start. Latest HRRR is waffling a bit on storm mode but pattern recognition is clear. Target the OFB intersection with a pre-frontal trough forecast in Mississippi. Upper level winds will strengthen late this afternoon. Low level shear will be locally favorable on the OFB. I would chase the cell on the OFB trough intersection or perhaps 1-2 cells east if they have better inflow.

Saw on Twitter where the NAM has started backing winds this morning for middle Tennessee for this afternoon right before the line gets there.