[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 170524
SWODY2
SPC AC 170523

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1223 AM CDT WED MAY 17 2006

VALID 181200Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

BLOCKING UPPER HIGH CENTER REMAINS STRONG OVER THE INTERMOUNTAIN
WEST...AND AN AMPLIFIED SPLIT FLOW PATTERN IS EXPECTED TO PERSIST
ACROSS MUCH OF NORTH AMERICA THROUGH THIS FORECAST PERIOD. 
HOWEVER...A SIGNIFICANT IMPULSE LIFTING OUT OF THE NORTHEAST PACIFIC
THROUGH RIDGE AXIS ACROSS THE CANADIAN ROCKIES WILL CONTRIBUTE TO
MID-LEVEL HEIGHT FALLS LATER TODAY/TONIGHT.  AND...FURTHER WEAKENING
OF UPPER RIDGE WILL OCCUR SOUTHWARD THROUGH THE NORTHERN PACIFIC
COAST STATES THURSDAY/THURSDAY NIGHT...AHEAD OF UPSTREAM TROUGH AXIS
SLOWLY APPROACHING THE PACIFIC COAST.

FARTHER EAST...MODELS INDICATE THAT A STRONG DIGGING JET STREAK IN
THE NORTHERN BRANCH OF THE WESTERLIES WILL CONTRIBUTE TO THE
DEVELOPMENT OF ANOTHER CLOSED LOW OVER THE GREAT LAKES/UPPER OHIO
VALLEY REGION. THIS FEATURE IS PROGGED TO OVERSPREAD ACROSS MUCH OF
THE REMAINDER OF THE NORTHEAST BY 12Z FRIDAY.

WITH THE INTERMOUNTAIN WEST ONLY CONTINUING TO GRADUALLY
MOISTEN...AND MOISTURE LEVELS EAST OF THE ROCKIES REMAINING
SEASONABLY LOW UNDER THE INFLUENCE OF SUCCESSIVE COOL/DRY SURGES
ASSOCIATED WITH PERSISTENT UPPER TROUGH...CONVECTIVE POTENTIAL IS
EXPECTED TO REMAIN LIMITED.  DESTABILIZATION IS EXPECTED TO BECOME
SUFFICIENT FOR AREAS OF SCATTERED THUNDERSTORMS THURSDAY/THURSDAY
NIGHT...BUT MOST ACTIVITY IS EXPECTED TO REMAIN RELATIVELY WEAK.

...EAST OF ROCKIES...
THE LEADING EDGE OF STRONGER MID-LEVEL COOLING/LIFT IN EXIT REGION
OF 70-90 KT CYCLONIC 500 MB JET STREAK STILL SEEMS LIKELY INTO MUCH
OF THE NORTHERN/CENTRAL APPALACHIANS BY MIDDAY THURSDAY.  THIS...IN
CONJUNCTION WITH FAVORABLE OROGRAPHIC FORCING...IS EXPECTED TO
SUPPORT INITIATION OF CONVECTIVE DEVELOPMENT...WHICH SHOULD DEVELOP
EASTWARD WITH UPPER FORCING TOWARD THE HUDSON VALLEY AND MID
ATLANTIC COASTAL AREAS THURSDAY AFTERNOON.  THOUGH CAPE WILL BE
WEAK...COOL THERMODYNAMIC PROFILES WILL BE SUPPORTIVE OF
HAIL...PERHAPS LOCALLY GUSTY WINDS...IN STRONGER CELLS...SOME OF
WHICH COULD APPROACH OR BRIEFLY EXCEED SEVERE CRITERIA.  THREAT
SHOULD DIMINISH QUICKLY THURSDAY EVENING WITH LOSS OF HEATING.

OTHERWISE...BANDS OF CONVECTION AND SCATTERED THUNDERSTORMS ARE
EXPECTED DURING THE DAYTIME HOURS SOUTH/SOUTHEAST OF DEVELOPING
UPPER LOW...PARTICULARLY NEAR THE SOUTHERN FRINGE OF THE MID-LEVEL
COLD CORE ACROSS THE OHIO VALLEY.

MODELS SUGGEST THAT ADDITIONAL THUNDERSTORMS ARE POSSIBLE BY LATE
THURSDAY/THURSDAY NIGHT FROM PARTS OF THE MID MISSOURI VALLEY INTO
THE MIDDLE MISSISSIPPI VALLEY. THIS IS EXPECTED AS MOISTURE OF
PACIFIC ORIGINS ADVECTS AROUND CREST OF UPPER RIDGE INTO FAVORABLE
LOWER/MID TROPOSPHERIC WARM ADVECTION REGIME EAST OF RIDGE...AND IN
WAKE OF CLOSED LOW.

...INTERMOUNTAIN WEST/PACIFIC COAST STATES...
SCATTERED THUNDERSTORM ACTIVITY IS EXPECTED ONCE AGAIN THURSDAY...
MAINLY SOUTH/WEST OF UPPER RIDGE...AND IN RESPONSE TO HEATING ACROSS
THE HIGHER TERRAIN.  MODELS SUGGEST THAT A WEAK IMPULSE EMBEDDED
WITHIN STRENGTHENING SOUTHERLY MID/UPPER FLOW COULD CONTRIBUTE TO
MORE EXTENSIVE CONVECTIVE DEVELOPMENT IN THE LEE OF THE SOUTHERN
CASCADES AFTER PEAK HEATING.  CAPE IS EXPECTED TO REMAIN
WEAK...LIMITING STRENGTH OF UPDRAFTS...BUT 700-500 MB FLOW ON THE
ORDER OF 30 TO 40 KTS COULD ENHANCE DOWNBURST POTENTIAL IN DRY DEEP
MIXED BOUNDARY LAYER.  ISOLATED DAMAGING WIND GUSTS APPEAR POSSIBLE
THROUGH THURSDAY EVENING...MAINLY ACROSS PARTS OF CENTRAL/EASTERN
OREGON.

..KERR.. 05/17/2006