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April 24- 25 Severe storm thread

jaxjagman

By jaxjagman,
in Tennessee Valley

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jaxjagman

jaxjagman

Posted
Posted

 

DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1253 AM CDT THU APR 23 2015

   VALID 241200Z - 251200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND ERN
   KS TO WRN MO...

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF CNTRL TO EAST
   TX...NRN LA AND SRN AR...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN
   PLAINS...CNTRL PLAINS...OZARKS...ARKLATEX AND LOWER TO MID MS
   VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF WCNTRL TX...WRN
   KS...CNTRL TO ERN NEB...SRN IA...THE MID MS VALLEY...TN VALLEY AND
   CNTRL GULF COAST...

   ...SUMMARY...
   SEVERE THUNDERSTORMS WITH LARGE HAIL...WIND DAMAGE AND SOME
   TORNADOES WILL BE POSSIBLE ACROSS THE CENTRAL PLAINS SOUTHWARD INTO
   THE SOUTHERN PLAINS AND EASTWARD ACROSS THE ARKLATEX INTO THE LOWER
   TO MID MISSISSIPPI VALLEY. THUNDERSTORMS MAY ALSO DEVELOP ACROSS
   PARTS OF THE CENTRAL GULF COAST...CENTRAL HIGH PLAINS...CENTRAL
   ROCKIES AND INTERMOUNTAIN WEST.

   ...CNTRL AND ERN KS/WRN MO/NERN OK...
   AN UPPER-LEVEL TROUGH WILL PROGRESS QUICKLY NEWD INTO THE SRN AND
   CNTRL PLAINS ON FRIDAY AS A SFC LOW DEEPENS ACROSS THE WRN KS. A
   WARM FRONT SHOULD EXTEND ESEWD FROM THE LOW ACROSS CNTRL TO ERN KS
   AND INTO SRN MO. LARGE-SCALE ASCENT ASSOCIATED WITH THE APPROACHING
   UPPER-LEVEL TROUGH WILL AID CONVECTIVE DEVELOPMENT DURING THE LATE
   AFTERNOON ALONG THE WARM FRONT IN ECNTRL KS AND SWD ALONG A DRYLINE
   ACROSS SERN KS AND NERN OK. MODEL FORECASTS ARE IN GENERAL AGREEMENT
   THAT A CLUSTER OF THUNDERSTORMS WILL ORGANIZE ACROSS ERN KS LATE
   FRIDAY AFTERNOON AND MOVE INTO WRN MO DURING THE EARLY EVENING.

   FORECAST SOUNDINGS SOUTH OF THE WARM FRONT AT EMPORIA KS FOR 00Z/SAT
   SHOW MLCAPE NEAR 2500 J/KG WITH 65 KT OF 0-6 KM SHEAR. AS THE EXIT
   REGION OF A 65 TO 80 KT MID-LEVEL JET OVERSPREADS SERN KS...LIFT
   ASSOCIATED WITH THE JET AND STRONG DEEP-LAYER SHEAR WILL CREATE
   CONDITIONS FAVORABLE FOR SUPERCELLS...LARGE HAIL AND POSSIBLY
   TORNADOES. THE TORNADO THREAT MAY DEPEND UPON HOW MUCH
   DESTABILIZATION CAN OCCUR SOUTH OF THE WARM FRONT. DUE TO THE
   COUPLING OF THE LOW AND MID-LEVEL JETS...A STRONG TORNADO WOULD BE
   POSSIBLE IF ENOUGH DESTABILIZATION CAN OCCUR ACROSS SE KS FRIDAY
   AFTERNOON. THE MORE DOMINANT SUPERCELLS MAY PRODUCE HAILSTONES OF
   GREATER THAN 2 INCHES IN DIAMETER. A GRADUAL TRANSITION TO A
   ENHANCED WIND-DAMAGE THREAT COULD OCCUR AS A CONVECTIVE CLUSTER
   MOVES INTO WRN AND CNTRL MO DURING THE EVENING.

   ...SRN PLAINS/ARKLATEX/LOWER TO MID MS VALLEY...
   AN UPPER-LEVEL TROUGH WILL MOVE NEWD INTO SRN PLAINS AS A DRYLINE
   SETS UP FROM CNTRL OK SSWWD INTO WCNTRL TX. TO THE EAST OF THE
   DRYLINE...A MOIST AND UNSTABLE AIRMASS WILL BE IN PLACE FROM THE SRN
   PLAINS EWD INTO THE LOWER TO MID MS VALLEY. AS A 65 TO 80 KT
   MID-LEVEL JET PASSES OVER THE SRN PLAINS...LARGE-SCALE ASCENT WILL
   AID THUNDERSTORM DEVELOPMENT TO THE EAST OF THE DRYLINE ALONG THE
   I-35 CORRIDOR FROM AUSTIN TO DALLAS/FORT WORTH. THE NAM AND GFS BOTH
   SUGGEST A LARGE CLUSTER OF STORMS WILL ORGANIZE AND MOVE ENEWD
   ACROSS EAST TX INTO LA AND SRN AR DURING THE LATE AFTERNOON. AN MCS
   COULD EVENTUALLY MOVE EWD INTO THE LOWER TO MID MS VALLEY BY EARLY
   EVENING.

   FORECAST SOUNDINGS AT 21Z/FRI FOR WACO AND AUSTIN TX SHOW IMPRESSIVE
   THERMODYNAMICS WITH MLCAPE OF 2500 TO 3000 J/KG AND SFC DEWPOINTS IN
   THE LOWER 70S F. IN ADDITION...STRONG DEEP-LAYER SHEAR PROFILES ARE
   FORECAST WITH SUBSTANTIAL VEERING WITH HEIGHT FROM THE SFC TO 850 MB
   AND SPEED SHEAR IN THE LOW TO MID-LEVELS. THIS SHOULD BE FAVORABLE
   FOR SUPERCELLS WITH LARGE HAIL...WIND DAMAGE AND SOME TORNADOES. AS
   THE CORE OF THE MID-LEVEL JET PASSES BY DURING THE
   AFTERNOON...SUPERCELL ORGANIZATION MAY BE AIDED BY THE INCREASED
   LIFT AND SHEAR. DUE TO THIS...A STRONG TORNADO COULD OCCUR FROM THE
   I-35 CORRIDOR ENEWD INTO THE ARKLATEX DURING THE LATE AFTERNOON. AS
   AN MCS MOVES EWD ACROSS LA AND AR DURING THE EVENING...THE
   WIND-DAMAGE THREAT COULD BECOME ENHANCED IF A COLD POOL AND BOWING
   LINE SEGMENT CAN ORGANIZE ACROSS THE REGION.

 

 

DAY 3 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0226 AM CDT THU APR 23 2015

   VALID 251200Z - 261200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER TO
   MID MS VALLEY...OH VALLEY...TN VALLEY...ERN GULF COAST STATES AND
   SRN SC...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
   PLAINS...LOWER TO MIDDLE TX COAST AND NCNTRL FL...

   ...SUMMARY...
   ISOLATED TO SCATTERED STRONG TO SEVERE THUNDERSTORMS WITH WIND
   DAMAGE AND LARGE HAIL WILL BE POSSIBLE FROM THE LOWER TO MID
   MISSISSIPPI VALLEY EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS ON
   SATURDAY. MARGINALLY SEVERE THUNDERSTORMS WITH STRONG WIND GUSTS AND
   HAIL WILL BE POSSIBLE ACROSS NORTH-CENTRAL FLORIDA AND IN THE
   CENTRAL PLAINS. THUNDERSTORM DEVELOPMENT MAY ALSO OCCUR ACROSS THE
   CENTRAL HIGH PLAINS...CENTRAL ROCKIES AND INTERMOUNTAIN WEST.

   ...MID MS VALLEY/OH AND TN VALLEYS...
   AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE QUICKLY EWD ACROSS THE OH
   AND TN VALLEYS ON SATURDAY AND BECOME MUCH LESS AMPLIFIED DURING THE
   DAY. A BROAD WARM SECTOR SHOULD BE IN PLACE FROM THE OZARKS EWD
   ACROSS THE OH AND TN VALLEYS. AT THE SFC...A COLD FRONT IS FORECAST
   TO ADVANCE SEWD ACROSS THE LOWER OH VALLEY WITH A SFC LOW LOCATED
   AHEAD OF THE FRONT. SCATTERED TO NUMEROUS THUNDERSTORMS MAY BE
   ONGOING AT THE START OF THE PERIOD FROM KY SWD ACROSS TN WITH THIS
   CONVECTION MOVING EWD DURING THE DAY. RESIDUAL OUTFLOW BOUNDARIES
   FROM THE MORNING STORMS SHOULD CREATE FAVORABLE LOCATIONS FOR
   MESOSCALE SFC-BASED CONVECTION BY AFTERNOON. THE GREATEST CHANCE FOR
   AN MCS WOULD BE ACROSS KY AND TN AHEAD OF THE UPPER-LEVEL TROUGH
   WHERE SOME MODEL SOLUTIONS MAINTAIN A 40 TO 50 KT LOW-LEVEL JET.

   NAM FORECAST SOUNDINGS AT 21Z/SAT FOR NASHVILLE TN AND PADUCAH KY
   SHOW MODERATE INSTABILITY WITH MLCAPE IN THE 2000 TO 2500 J/KG RANGE
   AND STRONG DEEP-LAYER SHEAR OF 60 TO 65 KT. THIS SHOULD BE FAVORABLE
   FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS. THE STRONG SHEAR AND
   STEEP LAPSE RATES FROM 850 TO 500 MB WILL MAKE LARGE HAIL A
   POSSIBILITY WITH SUPERCELLS. WIND DAMAGE MAY ALSO OCCUR WITH
   SUPERCELLS AND ORGANIZED LINE SEGMENTS. A TORNADO OR TWO WILL BE
   POSSIBLE BUT THIS SHOULD BE DEPENDENT UPON MESOSCALE FACTORS. THE
   SEVERE THREAT SHOULD DROP OFF WITH NEWD EXTENT ACROSS NE KY WHERE
   INSTABILITY IS FORECAST TO BE WEAK SATURDAY AFTERNOON.

   ...LOWER MS VALLEY/CNTRL GULF COAST STATES...
   AN UPPER-LEVEL TROUGH IS FORECAST TO BECOME LESS AMPLIFIED AND MOVE
   QUICKLY EWD ACROSS THE OH AND TN VALLEYS ON SATURDAY. AT THE
   SFC...SOUTH SOUTHWEST FLOW WILL BE IN PLACE FROM THE TX COASTAL
   PLAIN EWD INTO THE CNTRL GULF COAST STATES. MODERATE INSTABILITY IS
   FORECAST TO DEVELOP ALONG THIS CORRIDOR WHERE SFC DEWPOINTS SHOULD
   BE IN THE UPPER 60S AND LOWER 70S F. THUNDERSTORMS MAY DEVELOP
   ACROSS THE REGION SATURDAY AFTERNOON BUT SUBSIDENCE IN THE WAKE OF
   AN EXITING MID-LEVEL JET COULD KEEP CONVECTIVE INITIATION ISOLATED.

   FORECAST SOUNDINGS AT JACKSON MS AND BATON ROUGE LA FOR 21Z/SAT SHOW
   MLCAPE AROUND 2000 J/KG WITH 50 TO 60 KT OF DEEP-LAYER SHEAR. THIS
   ALONG WITH VEERED SFC WINDS AND UNIDIRECTIONAL WIND PROFILES IN THE
   LOW TO MID-LEVELS WILL FAVOR MULTICELL LINE SEGMENTS WITH WIND
   DAMAGE POTENTIAL. IF A SUPERCELL OR TWO CAN DEVELOP...THEN LARGE
   HAIL AND AN ISOLATED TORNADO THREAT WILL ALSO BE POSSIBLE.

   ..BROYLES.. 04/23/2015

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Chinook

Chinook

Posted
Posted

This is a segment of the 06z SPC Day 2 Outlook (issued 4/24 06z, valid for 4/25) KY and TN discussion. a hatched 30% area for KY and TN.

 

 

.THERE IS INCREASING CONFIDENCE THAT SUBSTANTIAL WARM SECTOR
   RECOVERY WILL BE NOTED WITHIN VEERED FLOW REGIME SUCH THAT MODERATE
   BUOYANCY AND STRONGLY SHEARED PARAMETER FIELDS WILL BECOME
   SUPPORTIVE OF DISCRETE SUPERCELLS.  WHILE THE STRONGEST FORCING IS
   EXPECTED ALONG THE WARM FRONT...IMMEDIATELY AHEAD OF SFC LOW AS IT
   TRACKS ESEWD ALONG THE BOUNDARY...STORMS THAT DEVELOP JUST SOUTH OF
   THE WARM FRONT ACROSS KENTUCKY AND TENNESSEE SHOULD EASILY ROTATE AND VERY LARGE
   HAIL AND TORNADOES ARE EXPECTED.  CONDITIONS COULD EVOLVE SUCH THAT
   A FEW STRONG TORNADOES ARE POSSIBLE.  WILL CONTINUE TO MONITOR THIS
   REGION FOR POSSIBLE INCREASE IN SEVERE PROBABILITIES IN LATER
   OUTLOOKS.

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andyhb

andyhb

Posted
Posted

This should upgrade from enhanced to at least moderate risk as we get into late this evening or early Friday. Possibly even high risk, as day 1 outlook of 30 percent with significant severe possible is a high risk rating. Vs 30 percent being enhanced at day 2.

 

Too many questions involving the evolution of prior convection and potentially storm coverage will likely prevent them from going higher than moderate at least until Saturday morning. A 30% tornado risk with sig-hatching is enough for a high risk, not just sig severe.

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John1122

John1122

Posted
Posted

Too many questions involving the evolution of prior convection and potentially storm coverage will likely prevent them from going higher than moderate at least until Saturday morning. A 30% tornado risk with sig-hatching is enough for a high risk, not just sig severe.

 

I wonder, with the mention of the tornado threat in the disco, if it will warrant a high risk. I can't remember if we've had one since April 2011.

 

image002.png

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John1122

John1122

Posted
Posted

Forbes has essentially the entire Tennessee Valley in torcon 6 for Saturday. Peyton Manning is in town for the Orange and White game and I'd guess 90,000 people will show up, many under the influence of strong beverage, with a meet and greet on the field at 2 and the game starting at 4, the timing of these storms could be very critical for this area. UT is the worst about ever postponing events too.

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Mr Bob

Mr Bob

Posted
Posted

Forbes has essentially the entire Tennessee Valley in torcon 6 for Saturday. Peyton Manning is in town for the Orange and White game and I'd guess 90,000 people will show up, many under the influence of strong beverage, with a meet and greet on the field at 2 and the game starting at 4, the timing of these storms could be very critical for this area. UT is the worst about ever postponing events too.

 

Sitting at 40F this morning, find it hard to believe that this area is going to be threatened by tornadic activity tomorrow...include the contamination from the overnight/early morning rain and I think that is probably over done in the northeast.

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Chinook

Chinook

Posted
Posted

http://www.spc.noaa.gov/products/outlook/day2otlk.html

I'm somewhat surprised at the northward movement of the enhanced area in the new Day2 outlook.

12km NAM reflectivity forecasts show some high reflectivity, starting out west of Louisville tomorrow, continuing east a long way eastward to eastern Kentucky, to the North Carolina area. So I think the 30% (enhanced) area may be a fairly good forecast. Certainly, the CAPE/shear parameters are also favorable into TN, MS, and AL.

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nrgjeff

nrgjeff

Posted
Posted

Yes the hi-res NAM has intense cells starting from West Kentucky tracking along the KY/TN border in to NC. Cells appear to ride the warm front. Supercell is the likely storm mode up there along the WF, where locally backed surface winds can promote rotating storms. SPC is keying in on the WF too.

 

Severe parameters will be excellent farther south in other areas of the Valley but surface to 850 mb winds are a bit veered off for tornadoes. Plenty of energy upstairs for damaging wind and hail though. Hi-res NAM has more late afternoon storms AL/GA perhaps along outflow from morning rain. However surface winds are not forecast to back on the OFB like up on the WF.

 

Issues have always been the veered off low level winds and how morning rain impacts things. Of course guidance is trending toward enough heating to destabilize by afternoon. In the Plains it would be a lovely OFB setup. In the South it is conditional, esp with morning wave veering off low levels.

 

Strong features include a stout mid-level wave for the afternoon. A good punch is forecast at 500/700 mb. Though strongest 200-300 mb winds scoot east with the morning wave, winds stay up through afternoon. Storms will move fast adding to straight line wind potential. Finally although 850 is veered off it will stay moist, in contrast with such a wind direction in the Plains. If 850 winds can back just a bit near the WF, say SW instead of WSW, tornado potential increases. Appears surface winds should locally back to straight south or better. 

 

Conditional nature of the whole setup favors ENH over MDT at this time. We will know more Saturday morning..

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1234snow

1234snow

Posted
Posted

So how is this thing looking today? MRX seems to think it will mainly only affect TRI this evening in these parts.

SPC has moved the Enhanced area further north into mostly Kentucky.

320d43deab4275425ed59ef5b6598d4b.jpg

Not much rain here at all this morning. Looks like convection in AL/GA robbed us of moisture. So, now I guess it's a waiting game for this evening. Hopefully the sun can come out later today.

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JayCee

JayCee

Posted
Posted

 

MESOSCALE DISCUSSION 0460 NWS STORM PREDICTION CENTER NORMAN OK 0614 PM CDT SAT APR 25 2015 AREAS AFFECTED...CNTRL/SRN KY AND ADJACENT NRN TN CONCERNING...SEVERE THUNDERSTORM WATCH 116... VALID 252314Z - 260045Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 116 CONTINUES. SUMMARY...AN EVOLVING MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE TO BE ACCOMPANIED BY...PRIMARILY...A RISK FOR POTENTIALLY DAMAGING WIND GUSTS AND OCCASIONAL SEVERE HAIL AS IT SPREADS TOWARD THE TENNESSEE BORDER THROUGH 00-02Z. TRENDS WILL CONTINUE TO BE MONITORED FOR THE POSSIBILITY OF AN ADDITIONAL WATCH ACROSS PARTS OF NORTHERN MIDDLE AND EASTERN TENNESSEE.

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