SPC AC 021210
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0710 AM CDT WED JUL 02 2008
VALID 021300Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH
PLAINS...ACROSS THE MID MS VALLEY...INTO THE GREAT LAKES REGION...
...MID MS VALLEY INTO GREAT LAKES...
MORNING SURFACE ANALYSIS SHOWS COLD FRONT EXTENDING FROM NORTHERN
NEB INTO MN AND FAR NORTHERN WI. THIS FRONT WILL MOVE SOUTHWARD
TODAY IN ADVANCE OF STRONG UPPER TROUGH...AND WILL BE THE FOCUS FOR
SCATTERED STRONG TO SEVERE STORMS FROM LOWER MI INTO NEB/KS.
SOUTHERLY/SOUTHWESTERLY LOW LEVEL WINDS AHEAD OF FRONT WILL MAINTAIN
DEWPOINTS WELL INTO THE 60S. STEEP MID LEVEL LAPSE RATES WILL ALSO
CONTRIBUTE TO A VERY UNSTABLE AFTERNOON AIRMASS WITH MLCAPE VALUES
OF 2000-3000 J/KG.
ONGOING CONVECTION OVER IA/WI WILL LIKELY LINGER THROUGH THE MORNING
WITH A RISK OF ISOLATED HAIL. STORMS ARE EXPECTED TO INCREASE BY
EARLY AFTERNOON OVER SOUTHERN WI/NORTHERN IL AND SPREAD ACROSS LOWER
MI WITH A RISK OF A FEW SUPERCELLS. DAMAGING WINDS AND HAIL WILL BE
THE MAIN THREATS...BUT ISOLATED TORNADOES ARE ALSO POSSIBLE BY LATE
AFTERNOON AS LOW LEVEL WINDS STRENGTHEN.
FARTHER WEST...STORMS WILL INTENSIFY ALONG THE FRONT FROM NORTHERN
IL INTO PARTS OF EASTERN NEB/KS DURING THE LATE AFTERNOON. ALTHOUGH
VERTICAL SHEAR IS WEAKER IN THIS AREA...IT SHOULD REMAIN SUFFICIENT
FOR ORGANIZED MULTICELL STORMS CAPABLE OF LARGE HAIL AND DAMAGING
WINDS. ACTIVITY MAY SAG INTO CENTRAL/SOUTHERN MO OVERNIGHT.
...CENTRAL HIGH PLAINS...
SOUTHEASTERLY UPSLOPE FLOW PATTERN IS FORECAST TO DEVELOP THIS
AFTERNOON FROM THE BIGHORN MTNS OF WY INTO NORTHEAST CO. IT APPEARS
LIKELY THAT DEWPOINTS IN THE 50S AND STEEP MID LEVEL LAPSE RATES
OVER THIS REGION WILL YIELD AFTERNOON MLCAPE VALUES OF 1500-1800
J/KG. ALL MODELS ARE CONSISTENT IN DEVELOPING SCATTERED
THUNDERSTORMS ALONG THIS AXIS AND TRACKING ACTIVITY SOUTHEASTWARD
INTO THE NEB PANHANDLE DURING THE EVENING. DESPITE RATHER WEAK LOW
LEVEL WINDS...VEERING WITH HEIGHT AND FAVORABLE MID/UPPER LEVEL FLOW
WILL PROVIDE SUFFICIENT EFFECTIVE SHEAR FOR A RISK OF SUPERCELLS.
LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE...ALONG WITH AN
ISOLATED TORNADO.
...SRN ROCKIES...
DIURNAL STORMS WILL DEVELOP ALONG THE COMPLEX TERRAIN WITHIN A STEEP
LAPSE RATE ENVIRONMENT. THE DEEPLY MIXED BOUNDARY LAYER CONDITIONS
WITH DCAPES AOA 1000 J/KG SUGGEST THE POTENTIAL FOR LOCALLY STRONG
WIND GUSTS WITH SOME OF THE MORE INTENSE STORMS.
...PACIFIC NW...
FORCING FOR ASCENT ASSOCIATED WITH A SHORT WAVE TROUGH LIFTING NEWD
ALONG THE PACIFIC NW COAST COMBINED WITH OROGRAPHIC EFFECTS WILL
RESULT IN SCATTERED TSTM DEVELOPMENT THIS AFTERNOON INTO TONIGHT
OVER THE CASCADES...PERHAPS INTO COLUMBIA BASIN. CONVECTIVE
INSTABILITY IS FORECAST TO REMAIN SOMEWHAT MARGINAL...BUT THE
PRESENCE OF RELATIVELY STEEP LAPSE RATES SUGGESTS THE POTENTIAL FOR
A FEW STRONG STORMS CAPABLE OF HAIL AND STRONG WIND GUSTS.
...FL...
VERY MOIST BOUNDARY LAYER CONDITIONS AND RELATIVELY COOL
TEMPERATURES ALOFT WILL ONCE AGAIN CONTRIBUTE TO THE DEVELOPMENT OF
MODERATE INSTABILITY THIS AFTERNOON WITH MLCAPES OF 1000-2000 J/KG.
DIURNAL STORMS ARE EXPECTED TO BECOME FOCUSED ALONG STRENGTHENING
SEA BREEZE CIRCULATIONS WHERE LOCALLY STRONG WET MICROBURST ACTIVITY
IS POSSIBLE.
...NEW ENGLAND...
NEWD MOVEMENT OF MIDLEVEL THERMAL TROUGH COMBINED WITH DEWPOINTS IN
THE 60S WILL RESULT IN POCKETS OF MODERATE INSTABILITY TODAY WITH
MLCAPES OF 1000 J/KG. SCATTERED...DIURNAL TSTM DEVELOPMENT IS
EXPECTED BY AFTERNOON ALONG REMNANT SURFACE BOUNDARY WITHIN
KINEMATIC ENVIRONMENT EXHIBITING STRONG UPPER TROPOSPHERIC
WINDS...BUT GENERALLY WEAK MID TO LOWER-LEVEL FLOW. A FEW OF THE
STRONGER STORMS WILL BE CAPABLE OF STRONG WIND GUSTS AND SOME HAIL
INTO THIS EVENING.
..HART/JEWELL.. 07/02/2008
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