SWODY1
SPC AC 032021
DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0321 PM CDT SUN JUL 03 2011
VALID 032018Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS ERN MO INTO SRN IL AND IND...
...THERE IS A SLGT RISK OF SVR TSTMS OVER CNTRL AND ERN MT...
...THERE IS A SLGT RISK OF SVR TSTMS FAR SRN AZ...
...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF ERN WV AND NRN VA AS
WELL AS MD...
AMENDED TO ADD SMALL SLIGHT RISK FOR HAIL NRN VA INTO MD
SEVERE STORMS WILL PERSIST ACROSS ERN MO INTO IL WHERE EXTREME
INSTABILITY EXISTS WITH LARGE HAIL AND DAMAGING WIND GUSTS. ADJUSTED
SRN EDGE OF THE SLIGHT RISK SWD TO ACCOUNT FOR POSSIBLE PROPAGATION
THIS AFTERNOON.
HAVE ADDED A LOW END SLIGHT RISK FOR POSSIBLE WIND OVER SRN AZ PER
COORDINATION WITH LOCAL OFFICES.
AMENDED FOR STRONG CORES MOVING SEWD ACROSS WV/VA INTO MD THIS
AFTERNOON. STRONG INSTABILITY AND MARGINAL SHEAR WILL BE SUFFICIENT
TO PROMOTE MARGINALLY SEVERE HAIL NEAR 1.00 INCH DIAMETER.
..NWS.. 07/03/2011
.PREV DISCUSSION... /ISSUED 1124 AM CDT SUN JUL 03 2011/
...MT...
A STRONG UPPER HIGH WILL PERSIST OVER THE CENTRAL ROCKIES AND GREAT
BASIN TODAY...WHILE AN UPPER TROUGH ROTATES FROM THE PACIFIC
NORTHWEST STATES INTO SASKATCHEWAN. AHEAD OF THIS TROUGH...FULL
SUNSHINE IS EXPECTED ACROSS MUCH OF MT WHERE DEWPOINTS ARE IN THE
50S LEADING TO AFTERNOON MLCAPE VALUES OVER 1500 J/KG. IT APPEARS
LIKELY THAT SCATTERED THUNDERSTORMS WILL FORM OVER THE HIGHER
TERRAIN OF WESTERN MT AND SPREAD EASTWARD THROUGH THE AFTERNOON AND
EVENING. STEEP LOW/MID LEVEL LAPSE RATES AND STRONG DEEP LAYER
EFFECTIVE SHEAR WILL SUPPORT A RISK OF A FEW SUPERCELLS CAPABLE OF
LARGE HAIL AND DAMAGING WINDS. STORMS MAY ORGANIZE INTO A LINEAR
MCS DURING THE EVENING AS THE COLD FRONT SURGES SOUTHEASTWARD ACROSS
THE REGION...WITH A CONTINUED SEVERE THREAT.
...MO/IL/IND...
A REMNANT MCV FROM OVERNIGHT CONVECTION IS PRESENT THIS MORNING OVER
MO/IA. SEVERAL CLUSTERS OF THUNDERSTORMS ARE ONGOING OVER NORTHERN
MO IN ASSOCIATION WITH THIS FEATURE. HIGH CAPE VALUES AND SURFACE
DEWPOINTS WELL INTO THE 70S WILL LIKELY RESULT IN THUNDERSTORM
DEVELOPMENT EAST AND AHEAD OF THE MCV ALONG A SURFACE BOUNDARY OVER
EASTERN MO AND CENTRAL/SOUTHERN IL INTO SOUTHERN IND. DEEP LAYER
WIND FIELDS ARE ONLY MARGINALLY FAVORABLE FOR CONVECTIVE
ORGANIZATION. HOWEVER...DEGREE OF INSTABILITY AND STEEP LOW LEVEL
LAPSE RATES COUPLED WITH APPROACHING MCV MAY RESULT IN A CLUSTERING
OF SEVERE REPORTS LATER TODAY.
...AZ...
EASTERLY MID LEVEL WINDS OF 30+ KNOTS ARE PRESENT TODAY OVER
SOUTHERN AZ...IN A REGION WHERE SURFACE DEWPOINTS HAVE RISEN INTO
THE 60S AND PWAT VALUES EXCEED 1.5 INCHES. FULL SUNSHINE OVER THE
DESERTS MAY RESULT IN A FEW THUNDERSTORMS LATER TODAY. ANY STORM
THAT FORMS OVER SOUTHERN AZ WILL POSE A CONDITIONAL RISK OF DAMAGING
WIND GUSTS...ESPECIALLY FROM TUS/PHX WESTWARD.
HOWEVER...UNCERTAINTY INVOLVES AREAL COVERAGE OF STORMS. WILL
MAINTAIN ONLY LOW SEVERE PROBS AT THIS TIME AND MONITOR
OBSERVATIONAL TRENDS IN LATER UPDATES.
...MID ATLANTIC...
THUNDERSTORMS ARE LIKELY TO FORM LATER TODAY OVER THE MOUNTAINS OF
EASTERN WV AND WESTERN VA...SAGGING SOUTHEASTWARD THROUGH THE EARLY
EVENING. A FEW OF THESE STORMS MAY PRODUCE GUSTY WINDS AND HAIL.
WEAK STEERING FLOW AND LIMITED CONVERGENCE ARE EXPECTED TO PRECLUDE
A MORE ORGANIZED SEVERE EVENT.
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