[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 260638
SWODY1
SPC AC 260637

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0137 AM CDT FRI MAY 26 2006

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
NORTHEAST/MID ATLANTIC/SOUTHEAST/TN VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL AND NRN
PLAINS/HIGH PLAINS...

...SYNOPSIS...
PROGRESSIVE LARGE SCALE FLOW OF MODEST AMPLITUDE WILL CONTINUE
ACROSS THE CONUS THROUGH FRIDAY AS ONE DEEP LAYER CYCLONE MOVES FROM
THE GREAT LAKES TO THE NORTHEAST...AND A STRONG MID/UPPER LEVEL
TROUGH EVOLVES ACROSS THE INTERIOR WEST. A MID/UPPER LEVEL RIDGE
WILL SEPARATE THE TWO TROUGHS AND MOVE EAST FROM THE PLAINS TO THE
MIDWEST AND DEEP SOUTH DURING THE FORECAST PERIOD. HOT AND VERY
UNSTABLE CONDITIONS WILL AGAIN DEVELOP BENEATH THE RIDGE AXIS TODAY
WHERE A DEEP LAYER FRONTAL ZONE WILL EXIST. EARLY TODAY...THE FRONT
ORIGINATING WITH THE GREAT LAKES/NORTHEAST TROUGH...WILL EXTEND SWWD
ALONG THE APPALACHIANS...THEN WWD TO THE TN VALLEY...AND NWWD INTO
THE PLAINS. CONVECTIVELY ENHANCED COLD POOLS/OUTFLOW WILL LOCALLY
REINFORCE THE FRONTAL ZONE FROM THE APPALACHIANS TO THE PLAINS.

AS ERN TROUGH MOVES ACROSS THE NORTHEAST AND MID ATLANTIC...
ASSOCIATED COLD FRONT WILL DEVELOP EAST ACROSS THE APPALACHIANS AND
THEN MOVE OFF THE ATLANTIC COAST THROUGH THE PERIOD. THE BOUNDARY
WILL LIKELY BECOME QUASI-STATIONARY FROM THE SRN APPALACHIANS/TN
VALLEY TO THE LOWER MO VALLEY. AS WRN U.S. TROUGH SPREADS EAST AND
LOW LEVEL SLY FLOW INCREASES ACROSS THE PLAINS...THE FRONTAL ZONE
OVER THE PLAINS SHOULD REDEVELOP NWD FROM KS TO THE CNTRL/NRN
PLAINS...AS LEE TROUGH STRENGTHENS ACROSS THE HIGH PLAINS.

...NORTHEAST/MID ATLANTIC...
STRONG DYNAMIC FORCING/HEIGHT FALLS WITH THE UPPER TROUGH WILL ACT
ON INCREASING INSTABILITY TO AT LEAST MAINTAIN...AND POSSIBLY
ENHANCE...CONVECTIVE LINE MOVING EAST THROUGH THE AFTERNOON.
STRENGTHENING DEEP LAYER FLOW COINCIDENT WITH THE INCREASING
INSTABILITY SHOULD SUPPORT FAST MOVING LINE SEGMENTS WITH DAMAGING
WINDS AND PERHAPS SOME HAIL FROM THE LOWER HUDSON VALLEY SWD ACROSS
ERN PA AND NJ. FROM DELMARVA AREA SWD ACROSS THE VA/NC
CAPES...GREATER MOISTURE AND LATER ARRIVAL OF FORCING ASSOCIATED
WITH THE WITH THE UPPER TROUGH WILL ALLOW FOR GREATER
DESTABILIZATION THESE AREAS. SHEAR WILL INITIALLY BE LIMITED BUT
SHOULD INCREASE AS STORMS DEVELOP ON STRENGTHENING LEE TROUGH
THROUGH LATE AFTERNOON. POTENTIAL FOR MORE DISCRETE CONVECTION... AT
LEAST INITIALLY...AND POSSIBLE SEA/BAY/SOUND BREEZE INTERACTIONS MAY
RESULT IN SLIGHTLY GREATER SUPERCELL/LARGE HAIL THREAT...IN ADDITION
TO DAMAGING WINDS FROM POSSIBLE EVOLUTION INTO CONVECTIVE LINE.

...NRN/CNTRL PLAINS...
INCREASINGLY STRONG SWLY FLOW ALOFT AND GRADUALLY FALLING HEIGHTS
WILL STRENGTHEN LEE-TROUGHING ACROSS THE NRN AND CNTRL HIGH PLAINS
TODAY. A NUMBER OF LOW AMPLITUDE DISTURBANCES ROTATING NEWD OUT OF
THE LARGER SCALE WRN TROUGH ARE SUGGESTED BY MODEL GUIDANCE AND WILL
AID CONVECTIVE INITIATION ACROSS THE HIGHER TERRAIN. LOW LEVEL
UPSLOPE FLOW AND MOISTURE ADVECTION APPEAR TO BE GREATEST FROM NERN
CO NWD ACROSS THE WRN DAKOTAS THROUGH LATE EVENING. LEE-SIDE SURFACE
LOWS MAY FURTHER FOCUS CONVECTIVE DEVELOPMENT WITH ACTIVITY MOVING
EWD/NEWD INTO STRONGER INSTABILITY EAST OF THE LEE TROUGH/DRYLINE.
SEVERAL CLUSTERS OF STORMS/SUPERCELLS APPEAR LIKELY. LARGE HAIL AND
HIGH WINDS SHOULD ACCOMPANY THIS ACTIVITY AS IT SPREADS GENERALLY
NEWD THROUGH LATE EVENING WITH SOME POTENTIAL FOR ISOLATED TORNADOES
NEAR ANY SURFACE LOW AND/OR LEE TROUGH/RETREATING WARM FRONT
INTERSECTION. AN MCS OR TWO MAY EVOLVE THROUGH THE LATE
EVENING...ESPECIALLY NEAR THE RETREATING WARM FRONT OVER NEB...AND
PERHAPS ACROSS ND WHERE GUIDANCE DEPICTS STRONGER QG FORCING FOR
ASCENT WILL PERSIST INTO EARLY SATURDAY.

...HIGH PLAINS SERN CO SOUTH TO BIG BEND...
LEE TROUGH/DRYLINE WILL ALSO SPUR GENERALLY HIGH-BASED TSTM
DEVELOPMENT FROM SERN CO SWD TO THE RIO GRANDE BY AFTERNOON. WEAKER
LARGE SCALE FORCING FOR ASCENT ACROSS THESE AREAS SUGGESTS MORE
ISOLATED DEVELOPMENT. NONETHELESS...VERY HOT BOUNDARY LAYER AND
SUFFICIENT EFFECTIVE SHEAR WILL SUPPORT VIGOROUS SUPERCELL STORMS
WITH AT LEAST A LOW PROBABILITY THREAT OF LARGE HAIL AND DAMAGING
DOWNBURST WINDS.

...TN VALLEY ACROSS MID MS VALLEY AND LOWER MO VALLEY...
STRONG TO EXTREME INSTABILITY WILL DEVELOP ALONG THE STALLED FRONTAL
ZONE...BUT BENEATH RIDGING ALOFT AND STOUT CAPPING INVERSION. THERE
IS FURTHER UNCERTAINTY REGARDING AFTERNOON TSTM DEVELOPMENT ACROSS
PARTS OF THE REGION GIVEN ONGOING MCS ACTIVITY ACROSS KS AND SWRN
MO. 

FAVORABLE ORIENTATION/FORCING FROM MCS OUTFLOWS AND RESIDUAL
FRONT...COUPLED WITH LOCALLY INTENSE HEATING/DESTABILIZATION FROM TN
SEWD ACROSS SC SHOULD OVERCOME CAP THESE AREAS TO RESULT IN
POTENTIALLY EXPLOSIVE CONVECTIVE DEVELOPMENT. LARGE HAIL AND LOCALLY
DAMAGING WINDS APPEAR POSSIBLE DURING THE DAY FROM THIS CONVECTION.

HOWEVER...FROM THE MS RIVER NWWD ACROSS MO...GENERALLY WEAKER SHEAR
AND FORCING BENEATH MID LEVEL RIDGE...AND CURRENT UNCERTAINTIES
REGARDING MCS EVOLUTION...PRECLUDE HIGHER PROBABILITY SEVERE WEATHER
FORECAST OVER THIS REGION AT THIS TIME.

...SOUTH FL...
LATEST GUIDANCE INDICATED THAT DIURNAL TSTM DEVELOPMENT MAY COINCIDE
WITH THE ARRIVAL OF SLIGHTLY STRONGER WLY MID LEVEL FLOW ACROSS SRN
FL. STORMS DEVELOPING ON EAST COAST SEA BREEZE...AND ACROSS THE
KEYS...MAY PERSIST OR BECOME BETTER ORGANIZED TO PRODUCE AN ISOLATED
TORNADO...OR A COUPLE OF HAIL/WIND EVENTS. OVERALL POTENTIAL DOES
NOT APPEAR TO SUPPORT HIGHER PROBABILITIES AT THIS TIME.

..CARBIN/JEWELL.. 05/26/2006