SWODY1
SPC AC 271247
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT THU MAY 27 2010
VALID 271300Z - 281200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN ROCKIES TO THE NRN
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NORTHEAST
FROM NY/NJ TO DELMARVA...
...SYNOPSIS...
BROAD UPPER RIDGE WILL REMAIN ACROSS THE CENTER OF THE NATION TODAY
WITH LARGE SCALE TROUGHS CONTINUING ALONG BOTH COASTS. STRONGEST
ASCENT ON THE SYNOPTIC SCALE WILL LIKELY OCCUR WITH THE TROUGH IN
THE WEST AS MID LEVEL JET STREAKS AND ASSOCIATED VORT LOBES ROTATE
THROUGH THE LARGE SCALE CYCLONIC FLOW...FROM THE GREAT BASIN NEWD
ACROSS THE NRN ROCKIES.
IN THE EAST...WEAK HEIGHT FALLS AND BACKDOOR COLD FRONT WILL SETTLE
A BIT FARTHER SWWD TODAY WITH PRE-FRONTAL THERMAL/INVERTED TROUGH
AXIS SHIFTING FROM NY/NJ TO PA/DELMARVA REGION.
BENEATH THE UPPER RIDGE...FROM THE OH VALLEY WSWWD TO THE
PLAINS...DIFFUSE RESIDUAL FRONTAL BOUNDARIES AND CONVECTIVE OUTFLOWS
WILL PERSIST AMIDST WARM AND VERY MOIST AIR MASS.
...ID/MT TO ND...
QG FORCING FOR ASCENT WILL STRENGTHEN ACROSS ID/MT BENEATH EXIT
REGION OF MID/UPPER LEVEL SPEED MAX NOSING NEWD FROM THE GREAT
BASIN. SURFACE RESPONSE WILL BE IN THE FORM OF A LEE CYCLONE ACROSS
WY/MT WHERE LOW LEVEL MASS ADJUSTMENT WILL CONTRIBUTE TO STRONG
MOISTURE TRANSPORT AND INTENSIFYING UPSLOPE FLOW. DIURNAL HEATING OF
MOIST AIR MASS BENEATH STEEPENING LAPSE RATES ALOFT WILL RESULT IN
SBCAPE OF ABOUT 700 J/KG ACROSS CNTRL MT...UP TO OVER 2000 J/KG FROM
ERN MT INTO ND AND POINTS SOUTH.
THROUGH THE AFTERNOON...STORM INITIATION WILL LIKELY OCCUR ACROSS
THE HIGHER TERRAIN...FROM THE BITTERROOTS EWD. DESPITE WEAKER
INSTABILITY IN THESE AREAS...STEEPENING MID-LEVEL LAPSE RATES AND
STRONG FORCING FOR ASCENT SHOULD LEND SOME SUPPORT FOR A FEW
STRONGER LOW-TOPPED STORMS WITH HAIL.
ADDITIONAL DEVELOPMENT ON THE EDGE OF STRONG CAPPING APPEARS
POSSIBLE AS FORCING SPREADS EAST ACROSS THE REST OF MT LATER IN THE
DAY. THERE IS UNCERTAINTY REGARDING STORM COVERAGE ACROSS CNTRL/ERN
MT AND ND WITH SOME GUIDANCE SUGGESTING ONLY ISOLATED STORMS ACROSS
CNTRL/ERN MT TRACKING NEWD INTO CANADA LATE. HOWEVER...ANY STORMS IN
THIS ENVIRONMENT WILL LIKELY ACQUIRE SUPERCELL STRUCTURE GIVEN
STRONG SPEED AND DIRECTIONAL SHEAR AND ABUNDANT INSTABILITY. SEVERE
THREAT WITH THIS ACTIVITY WILL INCLUDE VERY LARGE HAIL AND DAMAGING
WINDS. TORNADO POTENTIAL WILL ALSO EXIST...ESPECIALLY WITH ANY
DISCRETE STORMS TAPPING INTO GREATER BOUNDARY LAYER MOISTURE NEAR
THE LEE CYCLONE AND/OR TRACKING NEAR THE WARM FRONT EXTENDING EWD
ACROSS ERN MT.
...NY/PA TO DELMARVA...
WEAK HEIGHT FALLS ASSOCIATED WITH DEEP CYCLONE EAST OF THE CANADIAN
MARITIME PROVINCES WILL LIKELY PRODUCE SUFFICIENT BACKGROUND
DEEP-LAYER ASCENT TO AID STORM INITIATION WITHIN PRE-FRONTAL TROUGH
AHEAD OF BACKDOOR COLD FRONT FROM SERN NY TO NJ/PA THIS AFTERNOON.
PRIOR TO STORM DEVELOPMENT...AIR MASS WILL BECOME INCREASINGLY
UNSTABLE WITH A N-S CORRIDOR OF SBCAPE OF AT LEAST 1000 TO 2000
J/KG.
STORM DEVELOPMENT WILL OCCUR ON THE WRN EDGE OF STRONGER FLOW ALOFT
WHERE BULK SHEAR AROUND 30KT WILL CONTRIBUTE TO UPDRAFT ENHANCEMENT
AND STORM LONGEVITY. AS STORM COVERAGE INCREASES...COLD POOL
DEVELOPMENT AND UNIDIRECTIONAL NWLY FLOW WILL FAVOR FORWARD
PROPAGATION INTO INSTABILITY AXIS. GUIDANCE INDICATES THE
DEVELOPMENT OF A STRONG/SEVERE MCS SPREADING SOUTH FROM PA/NJ TO
DELMARVA AREA THROUGH LATE EVENING. DAMAGING WINDS AND LARGE HAIL
SHOULD BE THE PRIMARY HAZARDS WITH THIS CONVECTION BUT A TORNADO
CANNOT BE COMPLETELY RULED OUT.
...OH VALLEY...
STRONG DESTABILIZATION IS FORECAST TO DEVELOP ALONG RESIDUAL FRONTAL
ZONE SITUATED ACROSS THE LOWER OH RIVER VALLEY. WEAK INHIBITION AND
VERY WEAK FLOW ALOFT SUGGEST A COMBINATION OF MULTICELL AND PULSE
CONVECTION. AREAS WITH GREATER DCAPE MAY EXPERIENCING A BETTER
CHANCE OF DAMAGING MICROBURST WINDS. STORM MERGERS/BOUNDARY
INTERACTIONS COULD BRIEFLY SUPPORT STRONGER UPDRAFTS AND MARGINALLY
SEVERE HAIL...AS WELL AS HEAVY RAIN.
...PAC NW...
COLD CORE LOW AND PERSISTENT LIFT WITHIN LARGE CYCLONIC CIRCULATION
MAY COMBINE WITH POCKETS OF STRONGER HEATING TO PROMOTE SCATTERED
LOW-TOPPED THUNDERSTORMS FROM NRN CA ACROSS PARTS OF SRN AND ERN
ORE. SHEAR WILL BE GENERALLY WEAK WITHIN/NEAR UPPER LOW CENTER BUT
LAPSE RATES AND LOW FREEZING LEVEL COULD CONTRIBUTE TO HAIL
PRODUCTION IN SOME OF THE STRONGER CELLS.
...CO TO NM...
SCATTERED DIURNAL CONVECTION OCCURRING WITHIN POCKETS OF STRONG
INSTABILITY /SBCAPE 500-1500 J PER KG/ MAY YIELD SOME HAIL AND GUSTY
WINDS ACROSS PARTS OF CO AND NM THIS AFTERNOON. WEAK SHEAR SHOULD
KEEP THE PROBABILITY OF SEVERE WEATHER LOW BUT NON-ZERO.
..CARBIN/ROGERS/GUYER.. 05/27/2010
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment