[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 040508
SWODY1
SPC AC 040506

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1206 AM CDT FRI AUG 04 2006

VALID 041200Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID
ATLANTIC AND SOUTHEAST...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN PLAINS FROM ND/NRN
MN TO WRN LAKE SUPERIOR...

...SYNOPSIS...
MODERATE ZONAL FLOW WITH PROGRESSIVE LOW-AMPLITUDE PERTURBATIONS
WILL PERSIST ACROSS THE NRN BORDER STATES THROUGH FRIDAY. AS A MID
LEVEL TROUGH PASSES OFF THE ERN SEABOARD...ASSOCIATED DEEP-LAYER
FRONTAL ZONE WILL SETTLE SEWD ACROSS THE CNTRL/SRN APPALACHIANS AND
MERGE WITH LEE-TROUGH FROM VA SWWD ACROSS THE CAROLINAS TODAY. THE
BOUNDARY WILL EXTEND WWD FROM THE TN VALLEY INTO THE SRN PLAINS
BENEATH WEAK ANTICYCLONIC FLOW ALOFT.

FROM THE NRN ROCKIES TO THE NRN PLAINS...A WEAK SHORT WAVE TROUGH
WILL PRECEED A STRONGER SYSTEM DIGGING SEWD FROM NWRN CANADA. THIS
LEAD IMPULSE WILL ENHANCE WARM AIR ADVECTION AND LIFT FROM THE
DAKOTAS EWD ACROSS NRN MN THROUGH TONIGHT...WHILE THE STRONGER
DISTURBANCE DRIVES A COLD FRONT SEWD INTO ERN MT AND WRN ND THROUGH
EARLY SATURDAY.

A COUPLE OF WEAK WAVES WILL TRAVEL ALONG THE SRN/SWRN PERIPHERY OF
THE SUBTROPICAL RIDGE AXIS. ONE OF THESE WAVES WILL CONTINUE TO
TRACK ACROSS FL AND THE NERN GULF COAST THROUGH TODAY. THE OTHER
WAVE WILL MOVE SLOWLY NWD FROM MEXICO AND ACROSS THE NM/AZ BORDER
AREA DURING THIS FORECAST PERIOD.

...SRN DELMARVA SWWD TO GA...
VERY MOIST AIR MASS AND HEATING WILL CONTRIBUTE TO THE DEVELOPMENT
OF STRONG INSTABILITY AGAIN TODAY FROM THE APPALACHIANS EWD TO THE
COAST. TSTMS WILL AGAIN DEVELOP ACROSS THE HIGHER TERRAIN AND NEAR
LEE-TROUGH IN ADVANCE OF DEEPER FRONTAL CIRCULATION SPREADING INTO
THE REGION THROUGH EVENING. WHILE EFFECTIVE SHEAR WILL REMAIN MEAGER
GIVEN NO MORE THAN 20KT MID LEVEL FLOW...LARGE SCALE MID LEVEL
DEFORMATION AXIS ATOP ABUNDANT BOUNDARIES TO FOCUS CONVECTION SHOULD
SUPPORT NUMEROUS PULSE AND MULTICELL STORMS. STEEP THETA-E LAPSE
RATES/HIGH DCAPE INVOF LEE-TROUGH/FRONT AND SEA-BREEZE MERGERS WILL
PROMOTE WET DOWNBURST POTENTIAL WITH ANTICIPATED STORM COVERAGE
WARRANTING HIGHER SEVERE PROBABILITIES/SLGT RISK.

...NRN PLAINS TO WRN LAKE SUPERIOR...
LEADING LOW AMPLITUDE IMPULSE AND WEAK HEIGHT FALLS WILL SPREAD EAST
FROM MT/WRN DAKOTAS COINCIDENT WITH INTENSE SURFACE HEATING ACROSS
THE NRN HIGH PLAINS. VERY STEEP LAPSE RATES ATOP DRY BOUNDARY LAYER
WILL RESULT IN STRONG INHIBITION OVER MUCH OF THE REGION THROUGH THE
DAY. HOWEVER...PERSISTENT ASCENT AND DESTABILIZATION WITHIN WARM
CONVEYOR BELT FROM ERN ND ACROSS MN MAY PROMOTE HIGH-BASED/ELEVATED
TSTM DEVELOPMENT ACROSS THESE AREAS THROUGH THE AFTERNOON. THIS
ACTIVITY MAY CONTINUE TO SPREAD EAST ACROSS NRN MN THROUGH THE
PERIOD AS WARM FRONT STRENGTHENS AHEAD OF THE STRONGER IMPULSE
DIGGING SEWD FROM CANADA. PRIMARY HAZARD WILL BE LARGE HAIL GIVEN
STEEP LAPSE RATES AND STRONG SHEAR. HOWEVER...ISOLATED DAMAGING
WINDS COULD ALSO EVOLVE IF ELEVATED CONVECTION CAN PERSIST NEAR EDGE
OF THE CAP AND THEN MOVE/BACKBUILD INTO HEATED AND DEEPLY MIXED AIR
MASS FROM ERN SD ACROSS CNTRL MN DURING THE AFTERNOON AND EVENING.

...TN VALLEY TO SRN PLAINS...
ISOLATED WET DOWNBURSTS COULD OCCUR AS HEATING AIDS PULSE STORM
DEVELOPMENT ALONG RESIDUAL FRONTAL ZONE THESE AREAS. VERY WEAK SHEAR
AND MEAGER LAPSE RATES INDICATE SEVERE THREAT SHOULD REMAIN LIMITED
IN TIME AND SPACE.

...SOUTHWEST...
WET DOWNBURST ACTIVITY MAY ALSO INCREASE AS SUBTROPICAL IMPULSE
ENHANCES TSTM ACTIVITY ACROSS THE SOUTHWEST. HOWEVER...WARM LAPSE
RATES AND LIMITED SHEAR SUGGEST ONLY AN ISOLATED THREAT OF DAMAGING
WINDS...BUT INCREASING POTENTIAL FOR LOCALLY HEAVY RAIN.

..CARBIN/JEWELL.. 08/04/2006