[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 190559
SWODY1
SPC AC 190558

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT MON JUN 19 2006

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OH VALLEY INTO THE NRN
APPALACHIANS AND NEW ENGLAND...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NRN AND
CNTRL PLAINS INTO THE MID MO VALLEY...

...SYNOPSIS...

SHORT WAVE TROUGH AND ASSOCIATED 40-50 KT MID-LEVEL FLOW WILL
TRANSLATE NEWD FROM THE UPPER OH VALLEY INTO NEW ENGLAND BY THIS
EVENING WHILE UPSTREAM 50-60 KT JET STREAK OVER THE MIDWEST DIGS
SEWD INTO THE OH VALLEY.  MEANWHILE IN THE W...SHORT WAVE TROUGH
CURRENTLY ALONG THE PACIFIC NW COAST WILL LIFT NEWD INTO THE NRN
ROCKIES WITH AN ACCOMPANYING BELT OF 40-50 KT MID-LEVEL FLOW
SPREADING ACROSS SAME REGION.

IN THE LOW-LEVELS...WEAK SURFACE FRONT FROM THE UPPER OH VALLEY INTO
TN VALLEY WILL PUSH EWD TODAY...REACHING NEW ENGLAND SWD INTO THE
DELMARVA BY THIS EVENING.  MEANWHILE...UPSTREAM BOUNDARY WILL SAG
SWD FROM THE SRN GREAT LAKES AND UPPER MIDWEST INTO THE OH VALLEY
TOWARD THE OH RIVER BY TONIGHT.  OVER THE HIGH PLAINS...LOW PRESSURE
WILL CONSOLIDATE OVER NERN WY BY THIS AFTERNOON OR EVENING AS COLD
FRONT PUSHES EWD THROUGH THE NRN ROCKIES.

...NORTHEASTERN STATES...

BROKEN LINE OF SHOWERS AND TSTMS ARE EXPECTED TO BE ONGOING AT THE
ONSET OF THE FORECAST FROM THE UPPER OH VALLEY WITHIN ZONE OF
DEEP-LAYER FORCING AHEAD OF SHORT WAVE TROUGH MOVING THROUGH THE OH
VALLEY.  DAYTIME HEATING COUPLED WITH MOIST BOUNDARY-LAYER
CONDITIONS /I.E. DEWPOINTS LARGELY IN THE 60S/ WILL SUPPORT
DESTABILIZATION OF DOWNSTREAM AIR MASS ACROSS NY/PA INTO NEW ENGLAND
WITH MLCAPES INCREASING TO 1000-2000 J/KG.

EXPECT REINTENSIFICATION OR RENEWED STORM DEVELOPMENT ALONG OR AHEAD
OF SURFACE FRONT BY EARLY TO MID AFTERNOON AS THE STRONGER FORCING
FOR ASCENT OVERSPREADS THIS DESTABILIZING AIR MASS.  DEEP...SWLY
TROPOSPHERIC FLOW WITH 35-45 KTS OF SPEED SHEAR WILL SUPPORT
EVOLUTION OF BOWING SEGMENTS CAPABLE OF DAMAGING WINDS ALONG WITH
SEVERE HAIL.

THIS SEVERE WEATHER THREAT WILL SPREAD EWD INTO WRN/CNTRL NEW
ENGLAND BY THIS EVENING...AND SWD THROUGH ERN PA/NJ AND SERN
NY...WITH STORMS GRADUALLY WEAKENING OR MOVING OFFSHORE THEREAFTER.

...OH VALLEY...

ADDITIONAL BROKEN LINES OF TSTMS ARE EXPECTED TO DEVELOP OVER
PORTIONS OF OH/IND/IL THIS AFTERNOON AS UPSTREAM JET STREAK AND
VORTICITY MAXIMUM DIG SEWD TOWARD THE REGION.  MODELS INDICATE SOME
DRYING IN THE BOUNDARY LAYER AS LOW-LEVEL WINDS BECOME MORE
SWLY/WLY.  HOWEVER...PRESENCE OF RELATIVELY STEEP LOW/MID-LEVEL
LAPSE RATES SHOULD SUPPORT AFTERNOON MLCAPES OF 1000-2000 J/KG. 
FORECAST SOUNDINGS INDICATE THAT VERTICAL SHEAR WILL BE SUPPORTIVE
OF SEVERE STORMS...INCLUDING SPLITTING SUPERCELLS CAPABLE OF LARGE
HAIL AND HIGH WINDS GIVEN 40-45 KTS OF DEEP UNIDIRECTIONAL SHEAR.

SEVERE POTENTIAL SHOULD TEND TO DIMINISH LATER THIS EVENING WITH THE
LOSS OF DAYTIME HEATING AS TSTMS APPROACH THE OH RIVER.

...NRN/CNTRL HIGH PLAINS INTO MID MO VALLEY...

AIR MASS IS FORECAST TO REMAIN RELATIVELY DRY OVER WRN PORTIONS OF
SLIGHT RISK AREA WITH DEWPOINTS OF 40-45 F.  HOWEVER...STEEPENING 
LOW/MID-LEVEL LAPSE RATES SHOULD SUPPORT AIR MASS DESTABILIZATION BY
AFTERNOON WITH MLCAPES INCREASING TO 500 J/KG. TSTMS ARE EXPECTED
TO BECOME INCREASINGLY LIKELY LATER TODAY OVER SWRN MT/NWRN WY AS
LOW-LEVEL OROGRAPHIC FORCING N OF DEVELOPING SURFACE LOW COUPLES
WITH STRENGTHENING DEEP LAYER ASCENT AHEAD OF APPROACHING MID-LEVEL
TROUGH.  FORECAST SHEAR PROFILES WILL SUPPORT HIGH-BASED SUPERCELLS
AND BOWING STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

STORMS SHOULD INCREASE IN COVERAGE LATE THIS AFTERNOON INTO EVENING
OVER NRN WY/CNTRL AND ERN MT WITH AN MCS EVENTUALLY SHIFTING EWD
INTO THE WRN DAKOTAS TONIGHT.  OTHER STORMS MAY DEVELOP TONIGHT
DOWNSTREAM FROM THIS EVOLVING MCS OVER CNTRL SD INTO WRN OR CNTRL IA
WITHIN INTENSIFYING LOW-LEVEL WAA PATTERN.  A FEW OF THESE STORMS
WILL BE CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WINDS.

NAM AND 4-KM WRF NMM GUIDANCE BOTH INDICATE A SECONDARY ZONE OF
CONVECTIVE INITIATION WITHIN UPSLOPE REGION OF ERN WY INTO NERN CO
THIS AFTERNOON.  HERE...BETTER LOW-LEVEL MOISTURE /I.E. LOWER TO MID
50S DEWPOINTS/ WILL SUPPORT STRONGER INSTABILITY WITH MLCAPES OF
1000-1500 J/KG.  SHOULD STORMS DEVELOP...KINEMATIC FIELDS WILL BE
SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE HAIL AND PERHAPS A TORNADO
OR TWO WITHIN THE FIST FEW HOURS OF INITIATION.  A SECOND MCS MAY
EVOLVE FROM THIS ACTIVITY WITH A WIND AND HAIL THREAT SPREADING EWD
INTO WRN AND CNTRL NEB OVERNIGHT.

..MEAD/CROSBIE.. 06/19/2006