Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 210600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT THU MAY 21 2015
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE BIG BEND REGION OF
SOUTHWEST TX TO THE WESTERN PART OF SOUTH TX...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS FAR EASTERN NC...
...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM SOUTHEAST NM TO
THE LOWER RIO GRANDE VALLEY...
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS NORTHEAST SC AND EASTERN
NC...
...THERE IS A MRGL RISK OF SVR TSTMS FROM SOUTHEAST TX THROUGH
SOUTHERN LA TO PARTS OF SOUTHERN AL AND THE WESTERN FL PANHANDLE...
...SUMMARY...
ISOLATED TO SCATTERED SEVERE STORMS ARE MOST PROBABLE OVER THE BIG
BEND AREA OF SOUTHWEST TEXAS INTO PART OF SOUTH TEXAS...AND ACROSS
EASTERN NORTH CAROLINA. SEVERAL STRONG STORMS ARE ALSO POSSIBLE
ALONG PARTS OF THE NORTHWEST AND CENTRAL GULF COAST DURING THE
AFTERNOON.
...SYNOPSIS...
A CYCLONIC FLOW REGIME IS EXPECTED TO DEVELOP ACROSS THE GREAT LAKES
AND OH VALLEY TO THE CAROLINAS AND NORTHEAST STATES TODAY AND
TONIGHT AS A CLOSED LOW MOVES FROM JAMES BAY INTO SRN QUEBEC. A
LOW-AMPLITUDE SHORTWAVE TROUGH WILL TRACK THROUGH THE BASE OF THE
LARGE-SCALE TROUGH ATTENDANT TO THE CLOSED LOW...MOVING FROM SRN WI
AND IA EWD THROUGH THE SRN GREAT LAKES AND OH VALLEY...REACHING THE
MID-ATLANTIC COAST AND SRN NEW ENGLAND BY 12Z FRIDAY. THESE
FEATURES WILL AID IN A BELT OF STRENGTHENING MID-LEVEL W/SWLYS FROM
THE OH/TN VALLEYS TO NC AND THE NORTHEAST STATES. IN THE
SOUTHWEST...A MIDLEVEL IMPULSE APPROACHING NRN BAJA AT 12Z SHOULD
EJECT NEWD REACHING AZ/SWRN NM BY PEAK HEATING...AND THEN MOVE TO
THE CENTRAL HIGH PLAINS BY EARLY FRIDAY MORNING. AT THE SURFACE...A
WEAK FRONTAL WAVE SHOULD TRACK ALONG A BAROCLINIC ZONE FROM NRN SC
TO THE NC OUTER BANKS TODAY AND MOVE OFFSHORE THIS EVENING. THE
TRAILING PORTION OF A COLD FRONT SHOULD WEAKEN AS IT ADVANCES SWD
THROUGH THE SERN STATES...CENTRAL GULF COAST REGION AND LOWER MS
VALLEY...WHILE THE WRN EXTENSION OF THIS BOUNDARY STALLS OVER SOUTH
TX.
...SERN NM/SW TX TO PARTS OF THE LOWER RIO GRANDE VALLEY...
E/SELY LOW-LEVEL WINDS WILL MAINTAIN A MOIST BOUNDARY LAYER FROM THE
LOWER RIO GRANDE VALLEY TO THE TX BIG BEND REGION WITH SURFACE DEW
POINTS IN THE 60S. SURFACE HEATING SOUTH OF THE STALLED FRONT IN
SOUTH TX NWWD TO THE BIG BEND REGION WILL CONTRIBUTE TO THE
DEVELOPMENT OF A MODERATELY UNSTABLE ENVIRONMENT. UPSLOPE FLOW INTO
THE HIGHER TERRAIN OF SOUTHWEST TX AND THE HIGHER TERRAIN OF NERN
MEXICO COMBINED WITH FORCING FOR ASCENT ATTENDANT TO WEAK LEAD
MIDLEVEL IMPULSE SHOULD SUPPORT ISOLATED TO SCATTERED TSTM
DEVELOPMENT. AS STORMS MOVE OFF THE HIGHER TERRAIN INTO THE
STRONGER INSTABILITY...STRONG EFFECTIVE BULK SHEAR WILL BE
SUPPORTIVE OF SUPERCELLS WITH LARGE HAIL AND DAMAGING WINDS THE
PRIMARY THREATS.
...EASTERN NC...
A RELATIVELY SMALL AND MODESTLY UNSTABLE WARM SECTOR IS EXPECTED TO
DEVELOP INLAND OF THE COAST AS THE SURFACE LOW TRACKS NEWD FROM NRN
SC. ALTHOUGH STRONGER HEIGHT FALLS ARE EXPECTED TO REMAIN NORTH OF
THE CAROLINAS...FORCING FOR ASCENT ATTENDANT TO WEAK HEIGHT FALLS
AND LOW-LEVEL WAA SHOULD PROVE FAVORABLE FOR TSTM DEVELOPMENT BY
EARLY AFTERNOON. STRENGTHENING WLY MIDLEVEL WINDS WILL RESULT IN
SUFFICIENT EFFECTIVE BULK SHEAR /UP TO 35 KT/ FOR MULTICELLS AND
PERHAPS A SUPERCELL. LOCALLY STRONG WIND GUSTS AND HAIL WILL BE THE
PRIMARY THREATS BEFORE THE SURFACE LOW AND COLD FRONT MOVE OFFSHORE.
...SOUTHEAST TX/SRN LA TO SRN AL/WRN FL PANHANDLE...
THE AIR MASS ACROSS THIS REGION IS EXPECTED TO BECOME MODERATELY
UNSTABLE BY AFTERNOON SUPPORTING TSTM DEVELOPMENT IN VICINITY OF THE
SWD-MOVING COLD FRONT AND SEA BREEZE INTERACTIONS. EFFECTIVE BULK
SHEAR OF 20-30 SUGGESTS PRIMARILY MULTICELLS WITH ACTIVITY BEING
ISOLATED TO SCATTERED...GIVEN THE LACK OF LARGE-SCALE FORCING FOR
ASCENT.
..PETERS/PICCA.. 05/21/2015
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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