Mar. 27-31 Severe Threats

[ClicheVortex2014]

ILN had a good disco this morning

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
958 AM EDT TUE MAR 29 2016



.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
MUCH OF THE TIME THIS MORNING SPENT IN THE WEDNESDAY/THURSDAY
PORTION OF THE FORECAST WITH DETAILING INBOUND RAIN CHANCES.

AT 12Z WEDNESDAY...VERY AMPLIFIED MID/UPPER FLOW PATTERN WILL BE
IN PLACE ACROSS THE CONUS WITH MASSIVE ERN PACIFIC RIDGE AND
ANOMALOUSLY DEEP CNTL ROCKIES TROUGH/CLOSED LOW...WITH MORE
BROADSCALE/STRONG RIDGE ACROSS THE ERN CONUS. THIS PATTERN FAVORS
A STRONG WAA REGIME IN LOW LEVELS ACROSS THE OHIO VALLEY AND
INDEED TEMPS WILL BE RISING QUICKLY ON WED AS SWLY FLOW RAMPS UP.
A BREEZY/GUSTY DAY WHICH STARTS SUNNY BUT MID/UPPER LEVEL MOISTURE
WILL INCREASE THROUGH THE DAY AS THETA-E ADVECTION STRENGTHENS
ABOVE H7 THROUGH THE DAY. LIKELY A THICKENING MID DECK ARRIVING
FROM WEST TO EAST THROUGH THE AFTERNOON...AND PROBABLY SOME DECENT
RADAR ECHO MANIFESTED IN THIS BY LATER AFTERNOON. HOWEVER...DRY
SUB-CLOUD LAYERS MEANS LIKELY ONLY A SPRINKLE OR A VERY ISOLD SHRA
IS POSSIBLE DURING THE DAY...AND MAINLY IN ERN IND/WRN OH. TEMPS
TO WARM SIGNIFICANTLY OVER TUES...WITH HIGHS IN THE UPPER 60S TO
LOWER 70S.

IMPORTANT SYNOPTIC SCALE PROCESSES DEVELOP DURING DAY WED WHICH
FORCES A SPLIT OF THE ENERGY OVER THE CNTL ROCKIES...SENDING A
SIGNIFICANT S/W TROUGH EAST/NORTHEAST INTO THE CENTRAL PLAINS
WHILE LEAVING A POSITIVE TILT S/W TROUGH LEFT MEANDERING ACROSS
THE DESERT SW. THE PROGRESSIVE/STRONGER FEATURE WILL REACH NEB/IA
THURSDAY EVENING INDUCING RAPID PRESSURE FALLS AND DEEPENING
SURFACE CYCLONE /988MB PER 29.00Z ECMWF OVER WISCONSIN/ BY
THURSDAY MORNING. WEAK SHORTWAVE TROUGH OVER ARK-LA-TEX GETS
PICKED UP IN STRENGTHENING MID LEVEL FLOW AND ROCKETS TOWARD THE
OHIO VALLEY LATER WED NIGHT. WITH MASSIVE RIDGE AND STRONG SFC
HIGH IN THE WRN ATLANTIC...AND DEEPENING SFC LOW MOVING INTO GREAT
LAKES...DYNAMICS REALLY INCREASE AND LOW LEVEL WIND FIELDS
RESPOND...WITH WIDE AGREEMENT BETWEEN DETERMINISTIC MODELS OF A
70-80KT H85 JET DEVELOPING TO OUR SOUTHWEST AND PUSHING RIGHT OVER
THE STATE OF OHIO ON THURSDAY MORNING. NO SURPRISE...THE MOISTURE
TRANSPORT IN THIS SCENARIO IS SIGNIFICANT/ANOMALOUS WITH H85
MOISTURE FLUX ANOMALIES EXCEEDING 5 SIGMA ABOVE CLIMO ON THE NOSE
OF THIS LLJ AS PWAT VALUES DRAMATICALLY INCREASE TO 1.25" FROM THE
0.20" VALUES SEEN ON TUESDAY. WITH THIS MUCH MASS FIELD RESPONSE
AND MOISTURE ADVECTION...CONTINUED VERY HIGH RAIN CHANCES
SPREADING WEST TO EAST ACROSS THE AREA WEDNESDAY NIGHT INTO
THURSDAY MORNING. THIS WILL LIKELY MANIFEST IN A LARGE SHIELD OF
MODERATE /SOMETIMES HEAVY/ RAIN...AND DESPITE MEAGER INSTBY ON
FORECAST SOUNDINGS...WOULD NOT BE AT ALL SURPRISED TO SEE A CLAP
OF THUNDER OR TWO ESPECIALLY ON THE BACK EDGE OF THE RAIN SHIELD
IN CLOSER PROXIMITY TO WEAK-MOD INSTABILITY DEVELOPING IN THE
APPROACHING WARM SECTOR. WED NIGHT TEMPS LIKELY STEADY-STATE OR
ONLY SLOWLY FALLING WITH WINDS STAYING UP UNDER THE STRONG LLJ.
THANKFULLY...LOWEST 1KM LAPSE RATES WILL BE RATHER STABLE THUS
STRONG GUSTS WILL BE KEPT AT BAY FOR MUCH OF THE NIGHT /ALTHOUGH
HIGHER RIDGES /LIKE THE BELLEFONTAINE RIDGE/ MAY BE QUITE GUSTY
THROUGH THE NIGHT.

WIND CONCERNS WILL LINGER INTO THURSDAY MORNING...ESPECIALLY AS
STEADY PRECIP COMES TO AN END AND TAIL END OF ANOMALOUS LLJ BEGINS
TO MIX OUT IN DIURNAL FASHION. IT IS IN THE 9AM TO 1PM TIMEFRAME
WHERE THERE IS CONCERN FOR A STRONGER GUST OR TWO TO REACH THE
SURFACE BUT THINK TIMING OF MIXING AND DEPARTURE OF LLJ ARE WELL
SYNCED TO KEEP LARGER WIND CONCERNS AT BAY. ATTENTION THEN TURNS
TO TIMING OF THE COLD FRONT ATTENDANT TO THE DEEPENING CYCLONE AND
HOW MUCH INSTBY BUILDS THIS FAR NORTH. 29.00Z NAM WAS A
STRONG/SLOW OUTLIER AND WOULD BRING CONCERN FOR A MORE ROBUST
SEVERE WEATHER THREAT...AND 29.00Z WAS FAR TOO PROGRESSIVE WITH
THE FRONT...WHICH LEAVES 29.00Z ECMWF WHICH PROBABLY HAS THE BEST
AND MOST CONSISTENT TIMING OF FRONTAL PASSAGE. STRONG FLOW /SHEAR/
WILL BE PRESENT AT ALL LEVELS OF THE TROPOSPHERE IN THIS REGIME
BUT IT WILL BE INSTBY THAT /ONCE AGAIN/ WILL BE IN QUESTION
DEPENDING HOW FAST MORNING RAINS END...HOW MUCH DESTABILIZATION IN
THE WARM SECTOR THU AFTN...AND TIMING/STRENGTH OF FRONTAL PASSAGE
WHICH WILL DETERMINE POTENTIAL FOR SEVERE WX. WILL NEED TO BE
WATCHED CLOSELY...AND NEW SWODY3 FROM SPC HAS MRGL RISK INTO WRN
CWA. ONE KEY IS THAT FORCING VIA THE SURFACE LOW/SHORTWAVE WILL BE
PULLING AWAY AS THE ORIENTATION OF THE ENTIRE TROUGH OVER THE NRN
CONUS REMAINS POSI-TILT...LEAVING A MOSTLY VEERED BOUNDARY LAYER
AND QUESTIONABLE LARGE SCALE ASCENT IN THE WAKE OF THE MORE
CERTAIN MORNING RAINS/STORMS ON THE STRONG LOW LEVEL JET. SO IT
WILL BE MOSTLY LEFT TO FRONTAL CONVERGENCE IN A MARGINALLY
UNSTABLE BOUNDARY LAYER TO DETERMINE SVR POTENTIAL...WHICH STILL
HAS SOME UNCERTAINTY GIVEN THE TIMING DIFFERENCES AS INSTBY
CORRIDOR LIKELY NARROW.

 

[Hoosier]

Last 3 runs of the GFS showing the slowing trend.

 

 

[ClicheVortex2014]

Last 3 runs of the GFS showing the slowing trend.

 

 

gfs.gif

[snowlover2]

New day 2

 

DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1211 PM CDT TUE MAR 29 2016

   VALID 301200Z - 311200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND
   SOUTHERN PLAINS TO THE MIDDLE AND LOWER MS VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE MIDWEST AND
   SOUTH-CENTRAL STATES...

   ...SUMMARY...
   STRONG TO SEVERE STORMS WILL BE POSSIBLE FROM PORTIONS OF THE
   CENTRAL AND SOUTHERN PLAINS INTO THE LOWER TO MIDDLE MISSISSIPPI
   VALLEY REGION ON WEDNESDAY.  THREAT MAY PERSIST INTO THE OVERNIGHT
   OVER THE LOWER MISSISSIPPI VALLEY AREA.  DAMAGING WIND...LARGE HAIL
   AND TORNADOES WILL BE POSSIBLE.

   ...SYNOPSIS...

   MULTIPLE ROUNDS/AREAS OF STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED
   ON WEDNESDAY FROM EAST TX AND THE LOWER MS VALLEY NORTHWARD ACROSS
   PARTS OF THE SOUTHERN/CENTRAL PLAINS AND ADJACENT MID-MO VALLEY. A
   POSITIVELY TILTED UPPER TROUGH WILL MIGRATE EASTWARD ACROSS THE
   PLAINS FROM THE SOUTHWESTERN STATES/SOUTHERN ROCKIES. INITIAL
   VORTICITY MAXIMA AHEAD OF THE MAIN TROUGH WILL OVERSPREAD PARTS OF
   THE SOUTHERN PLAINS/OZARKS DURING THE MORNING AND SHIFT NORTHEAST
   TOWARD THE MID-MS VALLEY DURING THE AFTERNOON/OVERNIGHT. AT THE SAME
   TIME...STRONG WARM ADVECTION REGIME WILL TRANSPORT RICHER GULF
   MOISTURE NORTHWARD FROM THE UPPER TX COAST/SABINE VALLEY THROUGH
   PORTIONS OF THE CENTRAL/SOUTHERN PLAINS AND LOWER/MID-MS VALLEY
   REGION. A SURFACE LOW OVER WESTERN NEB WEDNESDAY MORNING WILL TRACK
   EASTWARD ACROSS SOUTHERN NEB/NORTHERN KS WITH A COLD FRONT/DRYLINE
   EXTENDING SOUTHWARD THROUGH KS/OK INTO CENTRAL TX.

   ...EASTERN OK/TX INTO THE OZARKS AND LOWER/MID MS VALLEY --
   WEDNESDAY MORNING INTO EARLY AFTERNOON...

   SHORTWAVE IMPULSES WILL EJECT AHEAD OF THE MAIN UPPER TROUGH ACROSS
   THIS REGION DURING THE MORNING...AND THUNDERSTORMS MAY ALREADY BE
   ONGOING 12Z/WED ACROSS PARTS OF OK/TX INTO SW MO. WEAK TO MODERATE
   ELEVATED INSTABILITY WILL BE IN PLACE ATOP RESIDUAL EML...AND
   VERTICAL SHEAR WILL BE ADEQUATE FOR SEMI ORGANIZED STORM CLUSTERS.
   THIS EARLY ACTIVITY WILL INCREASE IN COVERAGE AND PRODUCE SPORADIC
   SEVERE HAIL THROUGH THE MORNING AND SHIFT EAST/NORTHEAST TOWARD THE
   OZARKS AND LOWER/MID-MS VALLEY REGION THROUGH THE AFTERNOON.

   ...SOUTHERN AND CENTRAL PLAINS -- WEDNESDAY AFTERNOON INTO THE
   EVENING...

   THE BREADTH OF MORNING ACTIVITY WILL HAVE AN IMPACT ON HOW THINGS
   EVOLVE DURING THE AFTERNOON ACROSS CENTRAL/EASTERN OK/TX...AND
   GREATER UNCERTAINTY EXISTS AS A RESULT. HOWEVER...DETERMINISTIC AND
   SOME HI-RES GUIDANCE SUGGESTS ADEQUATE RECOVERY WILL OCCUR ACROSS
   THE WARM SECTOR AND ADDITIONAL THUNDERSTORM DEVELOPMENT FROM EASTERN
   OK/TX INTO WESTERN AR/LA IS EXPECTED. THE SURFACE DRYLINE WILL SURGE
   EASTWARD DURING THE DAY TO ROUGHLY THE I-35 CORRIDOR FROM CENTRAL KS
   THROUGH CENTRAL OK INTO TX...AND AN UNCAPPED AND MODERATELY UNSTABLE
   AIRMASS WILL EXIST. GIVEN THE ORIENTATION OF THE UPPER
   TROUGH...FORCING FOR ASCENT WILL BE STRONGEST OVER KS AND THE MID-MO
   VALLEY...WEAKENING WITH SOUTHWARD EXTENT. HOWEVER...A SOUTHWESTERLY
   LLJ ACROSS THE SOUTHERN PLAINS TO THE OZARKS AND STRONGER
   CONVERGENCE ALONG THE MOIST AXIS SHOULD BE ENOUGH TO COMPENSATE FOR
   MORE SUBTLE FORCING. DEVELOPMENT DURING THE AFTERNOON IS LIKELY NEAR
   THE SURFACE LOW/TRIPLE POINT AND ALONG THE DRYLINE FROM PARTS OF
   EASTERN NEB/KS INTO SOUTHWEST IA/NORTHWEST MO.

   THERE MAY BE A RELATIVE MIN IN ACTIVITY ACROSS PARTS OF SOUTHEAST
   KS/NORTHEAST OK/SOUTHWEST MO...AND THEN REDEVELOPMENT ACROSS THE
   WARM SECTOR IN SOUTHEAST OK/NORTHEAST TX AND ADJACENT PARTS OF
   AR/LA. THERMODYNAMIC AND KINEMATIC PROFILES WILL SUPPORT ALL HAZARD
   TYPES BOTH NEAR THE SURFACE LOW AND SOUTHWARD ALONG THE DRYLINE AND
   THROUGH THE WARM SECTOR. LARGE HAIL WILL BE THE MAIN THREAT...BUT
   TORNADOES ARE ALSO POSSIBLE.

   GIVEN DISPARITY AMONGST DETERMINISTIC GUIDANCE REGARDING LOW LEVEL
   MOISTURE AND THE EASTWARD POSITION OF THE DRYLINE...IN ADDITION TO
   ADDED UNCERTAINTY DUE TO MORNING CONVECTION...NO UPGRADES WILL BE
   MADE AT THIS TIME...THOUGH MAY BE POSSIBLE IN SUBSEQUENT OUTLOOKS.

   ...ARKLAMISS REGION -- OVERNIGHT...

   STORMS MAY CONGEAL INTO A LINE OR MULTIPLE CLUSTERS AS THEY TRACK
   EAST/NORTHEAST INTO THE LOWER MS VALLEY DURING THE EVENING AND
   OVERNIGHT. ADDITIONALLY...A 50 KT SOUTHWESTERLY LOW LEVEL JET WILL
   BECOME FOCUSED OVER THIS REGION. STRONG WINDS AND PERHAPS A TORNADO
   WILL BE POSSIBLE WITH THIS ACTIVITY.

   ..LEITMAN.. 03/29/2016

 

 

[andyhb]

The deep layer shear, especially speed shear, is going bonkers in the OV on Thursday. It won't take a lot of turning in the low levels to rapidly increase SRH. Assuming there is enough instability (still a rather questionable outcome), could be looking at the potential for a few fast moving supercells.

[Hoosier]

The deep layer shear, especially speed shear, is going bonkers in the OV on Thursday. It won't take a lot of turning in the low levels to rapidly increase SRH. Assuming there is enough instability (still a rather questionable outcome), could be looking at the potential for a few fast moving supercells.

 

 

Yeah, speed shear certainly not lacking in this setup.  Surface low should be deepening at least gradually during the day on Thursday but I'm not sure if the low levels can stay a little less veered than progged.

[andyhb]

Yeah, speed shear certainly not lacking in this setup. Surface low should be deepening at least gradually during the day on Thursday but I'm not sure if the low levels can stay a little less veered than progged.

I think SSW surface winds could work, although any further shift towards southerly and your wind profile begins to resemble a certain event that is showing up in CIPS, but that's probably far-fetched.

[Chicago Storm]

As mentioned by others, the NAM looks good for Thursday. The GFS is still much faster and less impressive though.

12z NAM in S. IN at 21z...

[ClicheVortex2014]

GFS is starting to look better though. SRH has increased in the past few runs because as the system slows, the surface winds have trended more southerly. The biggest problem is the moisture it's showing. I honestly wouldn't expect anything less from the GFS. It'd be spectacular if GFS and NAM would agree on the quality of moisture... but I don't think that's possible. Regarding the moisture, I think it's safe to take a 70% blend of NAM and 30% of GFS. Euro will probably be in that ballpark.

[Hoosier]

I think SSW surface winds could work, although any further shift towards southerly and your wind profile begins to resemble a certain event that is showing up in CIPS, but that's probably far-fetched.

 

 

Yeah maybe...SSW with WSW mid level flow would give ~45 degrees of turning. 

[Stebo]

The Euro slowed down a tick this run. The cold front doesn't come through here until near 00z Friday or just before. Also shows convective streaks through the area and not in a linear blob but individual streaks, signaling cellular convection coming through.

[Chicago Storm]

The Euro slowed down a tick this run. The cold front doesn't come through here until near 00z Friday or just before. Also shows convective streaks through the area and not in a linear blob but individual streaks, signaling cellular convection coming through.

Indeed it did.

Closer to what the NAM is showing, and might make it chase worthy...depending on convective debris issues.

[OHweather]

Man, I need to decide by this evening if I am going to call off work and try to chase on Thursday. The Euro was encouraging, but there are still some questions regarding possibly veered low level winds and questions about instability due to rain/storms well ahead of the front. If I had more faith in the NAM I'd chance those 55kt storm motions and do it. I'm leaning "no" but I'm definitely a little torn.

[ClicheVortex2014]

Comparing CAPE between 00z Euro and 12z Euro. Note it's the same scale and same map placement, so you can flip between two tabs to compare.

 

00z run

 

12z run

[bl5585]

It's hard for me to tell on Wundermap. For the Euro am I correct thinking that the biggest threat starts in South IL and moves into IN and KY?

[Hoosier]

It's hard for me to tell on Wundermap. For the Euro am I correct thinking that the biggest threat starts in South IL and moves into IN and KY?

 

Threat would be questionable in southern IL with better chances farther east.  That being said, any more slowing down helps the chances in eastern IL.

[Hoosier]

PRELIMINARY LOCAL STORM REPORT  

NATIONAL WEATHER SERVICE PADUCAH KY  

138 PM CDT TUE MAR 29 2016  

   

.TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON  

   

.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.  

 

..REMARKS..  

 

0700 PM TORNADO 4 S CROFTON 36.99N 87.48W  

03/27/2016 CHRISTIAN KY NWS STORM SURVEY  

 

AN EF2 TORNADO TOUCHED DOWN 2.5 MILES NORTHEAST OF  

CERULEAN JUST EAST OF THE TRIGG/CHRISTIAN COUNTY LINE AT  

700 PM CDT. THE TORNADO TRAVELED EAST NORTHEAST FOR 15.7  

MILES, ENDING 4.3 MILES EAST OF CROFTON AT 721 PM CDT.  

MAXIMUM WINDS WERE ESTIMATED AT 115 MPH. AVERAGE WIDTH  

WAS 100 YARDS WITH A MAXIMUM OF 200 YARDS. SIXTEEN BARNS  

WERE DESTROYED, 10 OTHER BARNS HAD MINOR TO MODERATE  

DAMAGE, 2 HOMES SUSTAINED MODERATE DAMAGE, 10  

TRACTORS/FARM IMPLEMENTS WERE DAMAGED.  

 

0711 PM TORNADO 5 W CROFTON 37.05N 87.57W  

03/27/2016 CHRISTIAN KY NWS STORM SURVEY  

 

A EF1 TORNADO TOUCHED DOWN 5.4 MILES WEST OF CROFTON AT  

711 PM CDT AND TRAVELED EAST NORTHEAST FOR 3.4 MILES TO 2  

MILES WEST OF CROFTON AT 717 PM CDT. SURVEY REVEALED  

MINOR ROOF DAMAGE TO 2 HOMES. OTHERWISE A FEW TREES WERE  

UPROOTED OR SNAPPED WITH OTHER LARGE LIMBS DOWN. AVERAGE  

WIDTH WAS 75 YARDS.  

 

0735 PM TORNADO 5 SW GREENVILLE 37.16N 87.24W  

03/27/2016 MUHLENBERG KY NWS STORM SURVEY  

 

AN EF0 TORNADO TOUCHED DOWN AT 735 PM CDT 2.7 MILES  

SOUTHEAST OF WHITE PLAINS, OR JUST WEST OF THE  

CHRISTIAN/MUHLENBERG LINE. THIS TORNADO TRAVELED  

NORTHEAST INTO MUHLENBERG COUNTY TO 5.2 MILES SOUTHWEST  

OF GREENVILLE AT 740 PM CDT. THIS TORNADO CAUSED MAINLY  

TREE DAMAGE. AVERAGE WIDTH WAS 50 YARDS.  

[Hoosier]

18z NAM is coming in a tick slower.

[ClicheVortex2014]

And bringing dew points further north... nice.

[ClicheVortex2014]

18z NAM is still slower than Euro, also has higher instability. Peak in Illinois/Indiana area is ~2300 j/kg... on Euro it's around 1600 j/kg.

[HillsdaleMIWeather]

IWX wrote an essay this afternoon that I will sum up for everyone:

If the GFS/GEM verifies, a small but still there severe event would develop

If the NAM/ECMWF verifies a much more significant severe event would develop

Pretty much a watch and see type of forecast

[Hoosier]

The NAM solution has a pronounced secondary type low that serves to hang up the cold front...that's basically what the differences come down to.

[MoonLitScorpion502]

Hi, New here. My name is Donnie. From Louisville, Kentucky.

[tornadohunter]

Nam 4km continues to like a discrete / semi discrete solutions. STP is picture.

But yea....with the storm on Wednesday and models inability to accurately handle mcs/debris....this is a wait and see...

It's frustrating but models are #2016ing

[Stebo]

Both the 4 and 12km NAM are impressive, both have a strong squall line racing across lower Michigan around 00z with ample instability.

[HillsdaleMIWeather]

Both the 4 and 12km NAM are impressive, both have a strong squall line racing across lower Michigan around 00z with ample instability.

Would be one of those situations where it looks like a good chunk of embedded tornadoes would be possible. Not good.

[Hoosier]

Besides CAPE, very impressed by the other severe parameters on the NAM for late March...LI's of -10 to -11 into parts of northern/central IL along with a host of others strongly suggestive of severe storms.  Now just have to get it to verify. 

[Hoosier]

18z GFS perhaps a hair slower but nothing like the NAM. 

[Stebo]

18z GFS perhaps a hair slower but nothing like the NAM. 

Still baby stepping in the right direction, clearly the consensus is for a slower solution though.

[Hoosier]

FWIW, the 18z RGEM looks closer to the NAM than GFS, timing wise.