SPC AC 281943
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CDT WED MAY 28 2008
VALID 282000Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTN/EVE ACROSS PARTS OF
ERN NM....
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTN/EVE ACROSS PARTS OF
CNTRL/ERN CO AND WY....
...SYNOPSIS...
ALTHOUGH ANOTHER STRONG SHORT WAVE TROUGH IS NOW DIGGING TO THE EAST
SOUTHEAST OF HUDSON BAY...THE BROADER SCALE COLD NORTHERN BRANCH
TROUGH IS IN THE PROCESS OF BEGINNING TO SHIFT EASTWARD OUT OF THE
EASTERN CANADIAN PROVINCES AND NORTHEASTERN UNITED STATES. AS THIS
OCCURS...THE CENTER OF THE COLD SURFACE RIDGE ENCOMPASSING MUCH OF
THE NORTH CENTRAL AND NORTHEASTERN U.S. IS GRADUALLY WEAKENING...AND
SHIFTING EASTWARD. COOLER BOUNDARY LAYER AIR IS BEGINNING TO NOSE
SOUTHWARD TO THE LEE OF THE SOUTHERN APPALACHIANS...BUT THE FRONTAL
ZONE EXTENDING ACROSS THE TENNESSEE VALLEY AND OZARK PLATEAU INTO
THE SOUTHERN HIGH PLAINS IS IN THE PROCESS OF WEAKENING...AND WILL
CONTINUE TO DO SO THROUGH THE REMAINDER OF THE PERIOD. WITH
DESTABILIZATION LIMITED/SLOW TO OCCUR IN THE WAKE OF THIS
FEATURE...CONVECTIVE POTENTIAL ACROSS MUCH OF THE NATION IS AT A
RELATIVE MINIMUM.
HOWEVER...A STRONG MID/UPPER JET STREAK IS BEGINNING TO EMERGE FROM
THE BASE OF THE BROAD EASTERN PACIFIC/WESTERN U.S. SOUTHERN BRANCH
TROUGH...AND NOSE TOWARD THE CREST OF AN AMPLIFYING SUBTROPICAL
RIDGE OVER THE CENTRAL/SOUTHERN PLAINS. SMALLER SCALE PERTURBATIONS
ASSOCIATED WITH THIS FEATURE MAY CONTRIBUTE TO AREAS OF ENHANCED
CONVECTIVE DEVELOPMENT ACROSS PARTS OF THE NORTHERN INTERMOUNTAIN
REGION/NORTHERN ROCKIES AND IMMEDIATE LEE OF THE CENTRAL/SOUTHERN
ROCKIES. THIS IS WHERE MOISTURE LEVELS ARE STILL SOMEWHAT LOW...BUT
STEEP LAPSE RATES COULD SUPPORT ISOLATED SEVERE STORMS.
...PARTS OF CNTRL/ERN NEW MEXICO...
THE BEST LOW-LEVEL MOISTURE IS AVAILABLE TO CONVECTION NOW FORMING
ACROSS THE HIGHER TERRAIN FROM THE MOUNTAINS OF CENTRAL NEW MEXICO
INTO SOUTHWEST TEXAS. AS UPPER 50S/LOWER 60S SURFACE DEW POINTS
RETURN TO THE SOUTH OF THE RESIDUAL WEAKENING FRONTAL ZONE...MIXED
LAYER CAPE INCREASING UP TO 1000 J/KG...PERHAPS LOCALLY AS HIGH AS
2000 J/KG...WILL SUPPORT INTENSIFICATION OF ACTIVITY AS IT
PROPAGATES OFF THE HIGHER TERRAIN WITHIN MODEST SOUTHWESTERLY
MID/UPPER FLOW. COUPLED WITH VEERING WINDS WITH HEIGHT IN THE LOWER
THROUGH MID-LEVELS...DEEP LAYER SHEAR IS SUFFICIENT FOR SUPERCELLS
CAPABLE OF PRODUCING LARGE HAIL/LOCALIZED DAMAGING WIND GUSTS.
VORTICITY ASSOCIATED WITH A REMNANT SURFACE BAROCLINIC ZONE
EAST/SOUTHEAST OF ALBUQUERQUE MAY EVEN CONTRIBUTE TO THE RISK FOR A
TORNADO OR TWO.
...CENTRAL ROCKIES INTO THE MID MISSOURI VALLEY...
FORCING DOWNSTREAM OF AN IMPULSE NOW LIFTING INTO/THROUGH THE LOWER
COLORADO VALLEY MAY CONTRIBUTE TO SCATTERED STRONG/SEVERE STORMS TO
THE LEE OF THE FRONT RANGE OF THE ROCKIES. BUT...A MORE PROMINENT
CONVECTIVE CLUSTER MAY EVENTUALLY EVOLVE LATER TONIGHT IN A
DOWNSTREAM LOWER/MID TROPOSPHERIC WARM ADVECTION ACROSS PARTS OF THE
MID MISSOURI VALLEY. THIS IS WHERE AN ELEVATED MOISTURE RETURN MAY
ALSO CONTRIBUTE TO SUFFICIENT DESTABILIZATION FOR STORMS CAPABLE OF
PRODUCING MAINLY SMALL TO MARGINALLY SEVERE HAIL.
...GULF COAST/SOUTH ATLANTIC COAST STATES...
CONVECTIVE POTENTIAL STILL SEEMS LOW WITH STORMS NOW DEVELOPING NEAR
COLD FRONT ADVANCING TO THE LEE OF THE SOUTHERN APPALACHIANS ...AND
ALONG A REMNANT CONVECTIVELY GENERATED BOUNDARY ACROSS THE GULF
STATES. THIS IS PRIMARILY DUE TO WEAK INSTABILITY. BUT... RATHER
STEEP LOW-LEVEL LAPSE RATES IN THE PEAK AFTERNOON HEATING COULD
SUPPORT GUSTY WINDS NEAR STRONGER CELLS.
..KERR/KIS.. 05/28/2008
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