DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 282001
SWODY1
SPC AC 281959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN JUL 28 2013

VALID 282000Z - 291200Z

...NO SVR TSTM AREAS FORECAST...

...MID-ATLANTIC/NORTHEAST STATES...
LITTLE OR NO CHANGE TO PRIOR FORECAST REASONING ALTHOUGH LOW SEVERE
PROBABILITIES WERE EXTEND SOUTHWARD FOR ONGOING STORMS ACROSS
EAST-CENTRAL VA THIS AFTERNOON. HERE...THE BOUNDARY LAYER HAS WARMED
INTO THE MIDDLE/UPPER 80S F THIS AFTERNOON WITH 1000+ J/KG
MLCAPE...ALTHOUGH MID-LEVEL LAPSE RATES REMAIN WEAK.

...NORTHERN INTERMOUNTAIN REGION...
LOW SEVERE PROBABILITIES WERE EXTENDED WESTWARD INTO ADDITIONAL
PARTS OF WY AS WELL AS EASTERN ID IN ACCORDANCE WITH A SPEED MAX
NOTED IN WATER VAPOR IMAGERY/POCATELLO WSR-88D VWP DATA. MARGINAL
HAIL AND/OR STRONG WIND GUSTS WILL BE POSSIBLE ON A LOCALIZED BASIS
THIS AFTERNOON.

..GUYER.. 07/28/2013

.PREV DISCUSSION... /ISSUED 1124 AM CDT SUN JUL 28 2013/

...NRN AND CENTRAL HIGH PLAINS THIS AFTERNOON/EVENING...
A MIDLEVEL TROUGH OVER ALBERTA WILL CONTINUE MOVING SLOWLY EWD
TODAY...AS EMBEDDED/SUBTLE SPEED MAXIMA PIVOT EWD AROUND THE BASE OF
THE TROUGH OVER THE NRN ROCKIES. WEAK LEE CYCLOGENESIS IS EXPECTED
ACROSS SE MT/NE WY IN RESPONSE TO A GRADUAL INCREASE IN WLY FLOW
ALOFT WITH THE EMBEDDED SPEED MAXIMA...AND THIS WILL INDUCE SLY
LOW-LEVEL FLOW TO DRAW MOISTURE NWD FROM THE CENTRAL HIGH PLAINS.
POCKETS OF STRONGER SURFACE HEATING IN SRN/ERN MT AND NE WY WILL
ALLOW WEAK-MODERATE INSTABILITY TO DEVELOP BY AFTERNOON /MLCAPE
APPROACHING 1000 J PER KG/...ALONG WITH WEAKENING CONVECTIVE
INHIBITION. SCATTERED THUNDERSTORMS WILL FORM OVER THE HIGHER
TERRAIN OF S CENTRAL MT...AS WELL AS ALONG THE WEAK LEE TROUGH/COLD
FRONT IN ERN MT THIS AFTERNOON...AND STORMS WILL SPREAD EWD/NEWD
THROUGH THE EVENING. THE COMBINATION OF MODEST DEEP-LAYER SHEAR AND
BUOYANCY COULD SUPPORT A FEW ORGANIZED STORM CLUSTERS CAPABLE OF
PRODUCING ISOLATED HAIL AND WIND GUSTS NEAR SEVERE CRITERIA.

FARTHER S IN WY/CO...WIDESPREAD CLOUDS ARE PRESENT IN CONJUNCTION
WITH NEWD EXTENT OF A DEEP MONSOONAL MOISTURE PLUME. LAPSE RATES
AND SURFACE HEATING WILL BE LIMITED WITHIN THIS PLUME...WHICH WILL
KEEP BUOYANCY WEAK TODAY. STILL...CONVECTIVE INHIBITION WILL BE
QUITE WEAK WITHIN THE MOISTURE PLUME...AND VERTICAL SHEAR WILL BE
SUFFICIENT FOR ORGANIZED/SUPERCELL STORMS. THUS...A STRONGER STORM
OR TWO WILL BE POSSIBLE WITHIN THE LARGER AREA OF CONVECTION THIS
AFTERNOON ALONG AND JUST E OF THE FRONT RANGE...WITH MARGINAL
POTENTIAL FOR STRONG WIND GUSTS.

...NE VA/NRN MD TO CENTRAL/ERN NY TODAY...
CLUSTERS OF CONVECTION/ISOLATED THUNDERSTORMS ARE MOVING NEWD FROM
NE PA INTO S CENTRAL NY AS OF LATE MORNING...WHICH APPEAR TO BE
ASSOCIATED WITH AN EMBEDDED SPEED MAX ROTATING NNEWD OVER WRN PA/NY.
THE CONVECTION IS ALSO OCCURRING IN A MOIST ENVIRONMENT /PW VALUES
OF 1.5 TO 1.75 INCHES/ WITH POOR LAPSE RATES...AND LARGELY
UNIDIRECTIONAL WIND PROFILES WITH SOME DEEP-LAYER SPEED SHEAR.
THUS...ORGANIZED CLUSTERS/BOWING SEGMENTS WILL CONTINUE TO BE
POSSIBLE THROUGH THE AFTERNOON...WITH ADDITIONAL STORM DEVELOPMENT
EXPECTED FARTHER S TOWARD NRN MD. THOUGH ISOLATED STRONG/DAMAGING
GUSTS CAN BE EXPECTED...MORE WIDESPREAD SEVERE STORMS ARE NOT
EXPECTED AS A RESULT OF LIMITED BUOYANCY AND DOWNDRAFT
POTENTIAL...AS WELL AS MARGINAL LOW-LEVEL FLOW/SHEAR.

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