DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 270947
SWOD48
SPC AC 270947

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0347 AM CST THU FEB 27 2014

VALID 021200Z - 071200Z

...DISCUSSION...
SUNDAY /DAY 4/ MODELS HAVE TRENDED TOWARD THE ECMWF REGARDING THE
TIMING AND AMPLITUDE OF A SHORTWAVE TROUGH THAT WILL MOVE THROUGH
THE SRN PLAINS AND LOWER MS VALLEY AREA. PRECEDING THIS FEATURE AN
ARCTIC FRONT WILL ADVANCE SWD INTO A PORTION OF THE SRN PLAINS AND
LOWER MS VALLEY. LOWER VERTICAL RESOLUTION SPECTRAL MODELS TEND TO
BE A BIT SLOWER WITH SHALLOW ARCTIC SURGES...SO THE SOMEWHAT FASTER
NAM SOLUTION MAY BE REASONABLE. BY 12Z SUNDAY THIS BOUNDARY WILL
LIKELY EXTEND FROM NRN AR SWWD INTO NWRN TX AND ADVANCE TO SCNTRL TX
INTO NRN LA EARLY SUNDAY EVENING.

DEWPOINTS IN THE UPPER-MID 60S WILL HAVE ADVECTED THROUGH THE TX
PRE-FRONTAL WARM SECTOR WITH LOW-MID 60S EXPECTED FARTHER EAST INTO
THE LOWER MS VALLEY. MODERATE INSTABILITY MAY RESIDE OVER NWRN AND
NCNTRL TX WED MORNING WHERE RICHER MOISTURE WILL HAVE ADVECTED
BENEATH STEEPER LAPSE RATES...BUT ATMOSPHERE IN THIS REGION MAY
REMAIN CAPPED. STORMS MAY INITIATE ALONG THE FRONT OVER NCNTRL TX
DURING THE MORNING AND SUBSEQUENTLY DEVELOP SEWD THROUGH ERN
TX...REACHING THE LOWER MS VALLEY BY EVENING. WINDS IN THE SFC-700
MB LAYER ARE INITIALLY EXPECTED TO BE MODEST...BUT WITH VERTICAL
SHEAR THROUGH A DEEPER LAYER OF 40+ KT. A FEW STORMS FROM NCNTRL
THROUGH ERN TX MAY POSE A THREAT FOR ISOLATED LARGE HAIL AND
DAMAGING WIND...THOUGH THERE MAY BE SOME TENDENCY FOR ANY STORMS
DEVELOPING ON THE FRONT TO BE UNDERCUT WHICH WOULD MITIGATE THE WIND
THREAT.

OVERNIGHT...THE LLJ IS FORECAST TO STRENGTHEN OVER THE LOWER MS
VALLEY WHERE INSTABILITY WILL BE SOMEWHAT WEAKER. SOME THREAT WILL
PERSIST FOR ISOLATED DAMAGING WIND GUSTS ALONG WITH A CONDITIONAL
THREAT FOR A TORNADO...BEFORE ACTIVITY BEGINS TO OUTRUN MOIST AXIS
LATER SUNDAY NIGHT.

WHILE AN INTRODUCTION OF AT LEAST A LOWER END SLIGHT RISK AREA IS
PROBABLE IN LATER UPDATES...CONFIDENCE IS NOT SUFFICIENT AT THIS
TIME TO DELINEATE A 30% OR GREATER COVERAGE AREA. BEYOND DAY 4
OVERALL SEVERE POTENTIAL APPEARS LOW UNTIL POSSIBLY DAY 8 ACROSS FL.

..DIAL.. 02/27/2014

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