RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0728 AM CDT THU MAY 17 2012
VALID 171300Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...SE ATLANTIC STATES TODAY...
A MIDLEVEL TROUGH OVER GA AND THE NE GULF OF MEXICO WILL EVOLVE INTO
A WEAK CLOSED AS IT DRIFTS EWD TO THE SE ATLANTIC COAST...WHILE WEAK
SURFACE CYCLOGENESIS IS EXPECTED OFFSHORE BY EARLY FRIDAY.
MEANWHILE...CLOUD BREAKS FROM CENTRAL FL NWD TO THE COASTAL PLAINS
OF SE GA/SC WILL ALLOW SURFACE HEATING/ DESTABILIZATION LATER THIS
MORNING. BOUNDARY LAYER DEWPOINTS IN THE MID 60S N AND UPPER 60S
S...AS WELL AS COOL 500 MB TEMPERATURES OF -11 TO -14 C...WILL
CONTRIBUTE TO MLCAPE VALUES OF 1000-1500 J/KG.
STORM DEVELOPMENT IS EXPECTED BY MID-LATE MORNING AS THE LOW LEVELS
WARM AND ANY LINGERING CONVECTIVE INHIBITION IS REMOVED...WITH
GREATER STORM COVERAGE IN ASSOCIATION WITH THE ATLANTIC COAST SEA
BREEZE. HERE...VERTICAL SHEAR WILL BE A LITTLE STRONGER THAN
ELSEWHERE /ESPECIALLY ACROSS FL IN PROXIMITY TO THE UPPER JET/...AND
THE STRONGEST STORMS COULD PRODUCE ISOLATED STRONG/DAMAGING WINDS
AND HAIL APPROACHING ONE INCH IN DIAMETER. THE MARGINAL SEVERE
STORM RISK WILL BE DIURNAL IN NATURE...WITH AN END TO THE RISK
EXPECTED AROUND SUNSET.
...CENTRAL HIGH PLAINS AND NRN ROCKIES THIS AFTERNOON/EVENING...
A WEAKENING MIDLEVEL TROUGH WILL DRIFT EWD FROM CO TO WRN KS BY
EARLY TONIGHT...AS AN UPSTREAM WAVE PROGRESSES INLAND TO THE GREAT
BASIN...AND A SEPARATE NRN STREAM TROUGH CROSSES BC/AB. LEE
CYCLOGENESIS WILL MAINTAIN A SLY LLJ ACROSS THE PLAINS THROUGH THE
PERIOD. HOWEVER...MOISTURE RETURN TODAY WILL BE LIMITED AS SURFACE
DEWPOINTS GENERALLY RANGE FROM THE LOW 40S IN ND TO THE MID 50S IN
SRN OK/N TX. STRONG DAYTIME HEATING/MIXING ALONG THE LEE TROUGH
WILL PROMOTE THE DEVELOPMENT OF WEAK INSTABILITY WITH MINIMAL
CONVECTIVE INHIBITION...AND A FEW HIGH-BASED STORMS MAY FORM LATE
THIS AFTERNOON/EVENING ACROSS THE HIGH PLAINS. VERTICAL SHEAR WILL
REMAIN MARGINAL AND PW VALUES SHOULD NOT EXCEED 0.50-0.70
INCHES...BUT INVERTED-V PROFILES COULD SUPPORT ISOLATED MICROBURSTS.
A SEPARATE AREA OF CONVECTION IS EXPECTED ACROSS THE NRN ROCKIES
AREA IN ADVANCE OF THE APPROACHING MIDLEVEL TROUGH. LIKE THE HIGH
PLAINS...MOISTURE/INSTABILITY WILL BE LIMITED. STILL...STEEP
LOW-LEVEL LAPSE RATES AND MODEST DEEP-LAYER SWLY FLOW COULD SUPPORT
STRONG GUSTS WITH HIGH-BASED STORMS THIS AFTERNOON/EVENING...MAINLY
INVOF THE MT/WY/ID BORDER REGION.
..THOMPSON/HURLBUT.. 05/17/2012
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SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CDT THU MAY 17 2012
VALID 171630Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...CENTRAL HIGH PLAINS...
WATER VAPOR IMAGERY SHOWS A COUPLE OF WEAK SHORTWAVE TROUGHS MOVING
ACROSS THE WESTERN U.S. ONE SUCH TROUGH IS NOW OVER CENTRAL CO AND
WILL TRACK INTO THE CENTRAL HIGH PLAINS LATER TODAY. LOW LEVEL
MOISTURE IS LIMITED IN THIS REGION...BUT STRONG HEATING AND STEEP
LOW/MID LEVEL LAPSE RATES ARE LIKELY TO RESULT IN SUFFICIENT
INSTABILITY FOR THE DEVELOPMENT OF A FEW ISOLATED THUNDERSTORMS THIS
AFTERNOON AND EARLY EVENING. THOSE STORMS THAT FORM WILL BE VERY
HIGH-BASED...BUT MAY BE CAPABLE OF LOCALLY GUSTY WINDS. THE MAIN
THREAT APPEARS TO EXTEND FROM WESTERN KS/EASTERN CO INTO THE
NORTHERN TX PANHANDLE.
...NORTHERN ROCKIES...
ANOTHER SHORTWAVE TROUGH IS CURRENTLY ALONG THE ORE/NORTHERN CA
COAST. THIS FEATURE WILL TRACK EASTWARD ACROSS THE NORTHERN GREAT
BASIN THIS AFTERNOON...WITH LARGE SCALE FORCING OVERSPREADING PARTS
OF ID/MT/WY. PRESENT INDICATIONS ARE THAT SCATTERED SHOWERS AND
THUNDERSTORMS WILL FORM OVER THE MOUNTAINS OF EASTERN ID/WESTERN WY
AND SPREAD EAST-NORTHEASTWARD INTO MT THROUGH THE AFTERNOON AND
EVENING. LOCALLY GUSTY/DAMAGING WINDS AND SMALL HAIL WILL BE
POSSIBLE IN THE STRONGER CELLS.
...SOUTHEAST STATES...
A WEAK UPPER LOW IS PRESENT TODAY OVER SC/GA. MOIST AND UNSTABLE
CONDITIONS EXTEND FROM PARTS OF THE FL PENINSULA NORTHWARD INTO
EASTERN GA/SC WHERE SCATTERED AFTERNOON THUNDERSTORMS ARE LIKELY.
WEAK FLOW WILL LIMIT CONVECTIVE ORGANIZATION. SIMILAR TO
YESTERDAY...THE STRONGER CELLS ACROSS THIS REGION WILL BE CAPABLE OF
LOCALLY GUSTY/DAMAGING WINDS AND HAIL.
..HART/SMITH.. 05/17/2012
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