SPC AC 230726
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
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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