[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 060618
SWODY2
SPC AC 060618

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0118 AM CDT THU APR 06 2006

VALID 071200Z - 081200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF EASTERN
ARKANSAS...NORTHEAST LOUISIANA...MUCH OF TENNESSEE...
MISSISSIPI...NORTHERN ALABAMA...AND NORTHERN GEORGIA...EXTREME
SOUTHWEST NORTH CAROLINA...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
LA/AR/MO...ACROSS THE MIDWEST/OH VALLEY...EAST TO WV...WRN
VA/NC/SC...AND NWRN GA..AND THE FL PANHANDLE...

...WIDESPREAD AND POSSIBLY SIGNIFICANT SEVERE WEATHER EPISODE
APPEARS INCREASINGLY LIKELY ACROSS PARTS OF THE LOWER MS VALLEY AND
TN VALLEY DURING FRIDAY....

...SYNOPSIS...
AN ACTIVE SPRINGTIME SEVERE WEATHER PATTERN WILL LIKELY CONTINUE
INTO DAY 2/FRIDAY AS POTENT TROUGH AND BELT OF 80-90KT MID LEVEL
FLOW SPREAD EAST FROM THE PLAINS TO THE MS AND TN VALLEYS. THE
FORECAST PERIOD WILL BEGIN WITH A DEEP OCCLUDED CYCLONE OVER THE
PLAINS...AND A MORE PROGRESSIVE NRN STREAM TROUGH DIGGING SEWD
TOWARD THE NRN GREAT LAKES. A BROAD RIDGE WILL COVER THE MUCH OF THE
INTERMOUNTAIN WEST...WHILE ANOTHER PACIFIC DISTURBANCE APPROACHES
THE WEST COAST.

NRN STREAM HEIGHT FALLS AND AMPLIFYING WRN RIDGE WILL INDUCE THE LOW
OVER THE PLAINS TO OPEN UP AND REDEVELOP EWD/SEWD ACROSS THE MS
VALLEY AS A FRONTAL WAVE/LOW. THIS WILL OCCUR AS THE LARGER SCALE
POSITIVE TILT TROUGH AXIS...AND ASSOCIATED DEEP LAYER BAROCLINIC
ZONE...SPREAD SEWD FROM THE GREAT LAKES/OH VALLEY...AND ANOTHER
FRONTAL SURFACE WAVE TRACKS EWD FROM OH TO NEW ENGLAND. GREAT LAKES
AND TN VALLEY SHORT WAVES WILL BEGIN TO PHASE BY SATURDAY WITH
RESULTING/ASSOCIATED COLD FRONT MOVING TOWARD THE ATLANTIC SEABOARD.

...ERN AR/LA ACROSS THE TN VALLEY...
GFS AND NAM APPEAR QUITE CONSISTENT WITH SYNOPTIC SCALE FEATURES
THAT SHOULD RESULT IN WIDESPREAD SEVERE WEATHER ACROSS THE SOUTH ON
FRIDAY. GFS HAS SHOWN A SLIGHT TREND TOWARD A SLOWER AND MORE
AMPLIFIED MID LEVEL TROUGH. THIS APPEARS REASONABLE AND ALLOWS FOR
THE DEVELOPMENT OF GREATER INSTABILITY ACROSS THE LOWER MS VALLEY
PRIOR TO ARRIVAL OF STRONGER FORCING.

GUIDANCE IS ALSO INDICATING THAT A POSSIBLE MCS WILL MOVE ACROSS
PARTS OF THE TN VALLEY THROUGH EARLY FRIDAY MORNING. THIS WOULD BE
WHAT REMAINS FROM PLAINS CONVECTION DURING DAY 1...SPREADING EAST
AND BEING SUSTAINED BY ISENTROPIC LIFT ON THE NOSE OF THE LOW LEVEL
JET. LOW LEVEL SSWLY FLOW IN THE WAKE OF THIS POTENTIAL MORNING
CONVECTION WILL TRANSPORT HIGHER THETAE AIRMASS FROM THE GULF INLAND
ACROSS LA/ERN AR/MS/AL AND TN. IT SEEMS REASONABLE TO EXPECT AT
LEAST MID 60S DEWPOINTS SPREADING NEWD ACROSS THESE AREAS BENEATH A
PLUME OF INCREASING STEEP LAPSE RATES AND STRENGTHENING MID LEVEL
FLOW.

FORCING ALONG POSSIBLE RESIDUAL MCS OUTFLOW BOUNDARY ACROSS THE TN
VALLEY...AND INCREASING LARGE SCALE ASCENT ASSOCIATED WITH THE
EJECTING UPPER TROUGH AND SURFACE WAVE ACROSS AR/LA...WILL
CONTRIBUTE TO STORM INITIATION FROM LATE MORNING INTO THE AFTERNOON.
MODERATE INSTABILITY...ESPECIALLY ACROSS THE LOWER MS VALLEY...WILL
FUEL ROBUST STORM UPDRAFTS AS SHEAR AND FORCING CONTINUE TO
STRENGTHEN ACROSS THE REGION INTO THE EVENING. EXPECT
VERY STRONG...PRIMARILY UNIDIRECTIONAL...DEEP LAYER FLOW TO RESULT
IN A NUMBER OF FAST MOVING BANDS...OR LINES...OF STORMS. SUPERCELLS
APPEAR LIKELY AND ACTIVITY NEAR THE SURFACE LOW...AND TRACKING
NEAR/ALONG ANY RESIDUAL OUTFLOW BOUNDARIES...COULD POSE A GREATER
RISK OF TORNADOES. WIDESPREAD DAMAGING WINDS...VERY LARGE HAIL...AND
POSSIBLY A COUPLE OF STRONGER FAST-MOVING TORNADOES COULD OCCUR.
SPECIFIC SEVERE PROBABILITIES FOR PARTS OF THE AREA MAY NEED TO BE
INCREASED IN LATER OUTLOOKS.

...MIDWEST/OH VALLEY...
EXPECT AIRMASS TO RECOVER ALONG THE OH RIVER VALLEY IN THE WAKE OF
MORNING CONVECTION...OR CONVECTIVE DEBRIS. GUIDANCE SUGGESTS THE
POSSIBILITY OF MODEST INSTABILITY FORMING AHEAD OF THE STRENGTHENING
COLD FRONT FORECAST TO MOVE INTO THE AREA AHEAD OF STRONG NRN STREAM
TROUGH. STORMS SHOULD INCREASE IN COVERAGE AND INTENSITY INTO THE
LATE AFTERNOON/EARLY EVENING AS FRONTAL CIRCULATION MOVES INTO THE
INSTABILITY AXIS FROM IL TO OH. LARGE HAIL AND DAMAGING WINDS APPEAR
TO BE PRIMARY THREATS.

...ERN PLAINS/MO...
A FEW LOW-TOPPED STORMS WITH HAIL COULD DEVELOP NEAR/WITHIN THE MID
LEVEL COLD POOL AS IT MOVES ESEWD ACROSS THE OZARKS THROUGH THE LATE
AFTERNOON. GENERALLY WEAK SHEAR AND INSTABILITY SHOULD LIMIT STORM
INTENSITY/DURATION.

..CARBIN.. 04/06/2006