Saturday, October 19, 2013

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 190441
SWODY1
SPC AC 190438

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CDT FRI OCT 18 2013

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS/FORECAST...
SHORTWAVE IMPULSES WILL MOVE THROUGH A BROAD AREA OF MID/UPPER-LEVEL
CYCLONIC FLOW COVERING MUCH OF THE CONUS. AT THE SFC...A COLD FRONT
WILL MOVE OFF THE LOWER TX COAST THIS MORNING WHILE SHIFTING SEWD
ACROSS THE GULF OF MEXICO. THE SAME FRONT WILL INITIALLY EXTEND NEWD
FROM THE ERN GULF COAST TO COASTAL NC...AND THIS FRONTAL SEGMENT
WILL BE SLOWER TO PROGRESS OFF THE ATLANTIC COAST. HOWEVER...AFTER
00Z...THE FRONT WILL BE OVERTAKEN BY A SURGE OF COOL/CONTINENTAL AIR
ATTENDANT TO AN IMPULSE QUICKLY ADVANCING FROM THE MIDDLE MS VALLEY
TO NEW ENGLAND. IN TURN...MOIST AND MARGINALLY UNSTABLE AIR ON THE
WARM SIDE OF THE BOUNDARY WILL BECOME INCREASINGLY CONFINED OVER
INLAND AREAS AND SUPPORT ISOLATED STORMS ACROSS PARTS OF THE SERN
STATES AND THE LOWER RIO GRANDE VALLEY OF TX. POOR TROPOSPHERIC
LAPSE RATES AND WEAK LOW-LEVEL FLOW RENDER NO SEVERE PROBABILITIES.

COLD MID-LEVEL CONDITIONS ACCOMPANYING THE AFOREMENTIONED IMPULSE
/E.G. H5 TEMPERATURES MORE NEGATIVE THAN -30C/ WILL GLANCE THE GREAT
LAKES REGION. THIS WILL ENHANCE CONVECTIVE BOUNDARY LAYER GROWTH
ATOP THE RELATIVELY WARMER WATERS OF THE GREAT LAKES TO SUPPORT
SCATTERED SHOWERS. FORECAST SOUNDINGS SUGGEST THAT NARROW CAPE
LAYERS MAY EXTEND MARGINALLY DEEP ENOUGH INTO ICING LAYERS ALOFT TO
SUPPORT A FEW VERY ISOLATED LIGHTNING STRIKES. THUNDERSTORM COVERAGE
IS EXPECTED TO REMAIN SUFFICIENTLY LOW TO PRECLUDE GENERAL
THUNDERSTORM AREAS. ALSO...DCVA PRECEDING THE IMPULSE MAY ENCOURAGE
THE DEVELOPMENT OF SMALL...LOW-TOPPED CONVECTIVE BANDS FROM THE
CNTRL/NRN APPALACHIANS TO NEW ENGLAND. BUOYANCY IS FORECAST TO BE
TOO LIMITED FOR GENERAL THUNDERSTORM DELINEATION.

..COHEN/GRAMS.. 10/19/2013

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