Thursday, April 19, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 191643
SWODY1
SPC AC 191640

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1140 AM CDT THU APR 19 2007

VALID 191630Z - 201200Z

..NO SVR TSTM AREAS FORECAST...

..SOUTHERN APPALACHIANS AND CAROLINAS THROUGH EARLY EVENING...
COMPACT MID LEVEL LOW CONTINUES TO PIVOT SOUTHEASTWARD OVER EASTERN
KY AT MIDDAY PER WATER VAPOR IMAGERY...WITH THIS FEATURE EXPECTED TO
REACH THE SC COAST LATE TONIGHT. IN ADDITION TO THE PARENT UPPER
LOW...A WEAK NW-SE ORIENTED BOUNDARY WILL PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT...WITH STORMS EXPECTED TO DEVELOP
SOUTHEASTWARD THROUGH WESTERN NC AND THE SC PIEDMONT/COASTAL PLAIN
THROUGH EARLY EVENING. IN ADDITION TO GUSTY WIND POTENTIAL...COLD
MID LEVEL TEMPERATURES /-23 C AT 500 MB PER 12Z WILMINGTON OH
OBSERVED RAOB/ AND ASSOCIATED STEEP LAPSE RATE ENVIRONMENT WILL
FAVOR HAIL POTENTIAL WITH SEMI-ORGANIZED MULTICELL/MARGINAL
SUPERCELL STORMS THROUGH EARLY EVENING.

..PORTIONS OF SD/NEB/KS THIS AFTERNOON AND TONIGHT...
WATER VAPOR IMAGERY FEATURES UPPER TROUGH SHIFTING NORTHWARD ACROSS
WY AND FAR SOUTHERN MT AT MIDDAY...WITH A PACIFIC/OCCLUDED FRONT
ADVANCING EASTWARD INTO THE WESTERN DAKOTAS/WESTERN NEB. BOUNDARY
LAYER MOISTURE ONLY IN THE 40S F AND EXISTING CLOUD COVER WILL
CONSIDERABLY LIMIT POTENTIAL INSTABILITY THROUGH THE AFTERNOON
ACROSS MUCH OF SD/NEB...HOWEVER AN ISOLATED HAIL PRODUCING STORM
CANNOT BE RULED OUT. ALTHOUGH CONDITIONAL...A RELATIVELY GREATER
SEVERE THREAT EXISTS LATE THIS AFTERNOON/EVENING WITH SOUTH EXTENT
ALONG THE SLOW EASTWARD MOVING FRONTAL BOUNDARY INTO CENTRAL
PORTIONS OF KS. EVEN WITH RISING UPPER HEIGHTS/ONSET OF UPPER
RIDGING...12Z DETERMINISTIC NAM/GFS AND 09Z SREF GUIDANCE SUGGEST
ISOLATED STORMS ARE PLAUSIBLE BY EARLY EVENING INTO CENTRAL
KS...WITH THE POSSIBILITY OF A FEW SUPERCELLS CAPABLE OF LARGE HAIL
AND GUSTY WINDS.

.GUYER/HART.. 04/19/2007

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