SWOD48
SPC AC 050854
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0254 AM CST THU FEB 05 2009
VALID 081200Z - 131200Z
...AN ACTIVE SEVERE WEATHER PATTERN MAY DEVELOP OVER THE
SOUTHERN/CENTRAL U.S. NEXT WEEK...
...DAY4/SUNDAY TO MONDAY MORNING...
LITTLE CHANGE IN OVERALL THINKING SINCE YESTERDAY WITH LATEST
GUIDANCE CONTINUING TO ADVERTISE THE EJECTION OF A VIGOROUS SHORT
WAVE TROUGH...AND ASSOCIATED 80-100KT MID LEVEL JET STREAK...FROM
NM/WEST TX TO THE CNTRL PLAINS LATE SUNDAY INTO MONDAY. ECMWF
CONTINUES TO RUN ABOUT 3-6H BEHIND GFS IN TERMS OF THE EMERGENCE OF
STRONGEST FORCING FOR ASCENT ACROSS TX/OK AREAS ON SUNDAY EVENING.
HOWEVER...VERTICAL MOTION FIELDS AMONGST THE MODELS ARE SIMILAR AND
STRONGLY INDICATE THE FORMATION OF A FAST MOVING SQUALL LINE
SPREADING EAST FROM TX TO WRN OK DURING THE LATE EVENING/OVERNIGHT
HOURS AS A SURFACE LOW DEEPENS OVER KS AND DRYLINE/WIND SHIFT SURGES
EWD.
DYNAMIC AND KINEMATIC ENVIRONMENT AS FORECAST CONTINUES TO SUPPORT
THE POTENTIAL FOR ORGANIZED TSTMS PRODUCING SOME HAIL AND HIGH WINDS
WITHIN THE ADVANCING SQUALL LINE. OVERALL SEVERE POTENTIAL WILL BE
LIMITED BY LACK OF GREATER MOISTURE AND GENERALLY WEAK INSTABILITY
/MUCAPE ONLY 150-300 J PER KG BASED ON GFS SOUNDINGS/. THE HIGHER
PROBABILITY OF SEVERE WEATHER SHOULD UNFOLD WITH INITIAL DEVELOPMENT
ACROSS TX WHERE STRONG DYNAMICS WILL ACT ON POTENTIALLY HIGHER
THETA-E AIR MASS ON THE APEX OF MODIFIED GULF MOISTURE RETURN.
OBVIOUSLY...IF GREATER MOISTURE TRANSPORT CAN EVOLVE AHEAD OF THIS
SYSTEM...STORM COVERAGE AND SEVERE POTENTIAL WILL BE GREATER.
...DAY5/MONDAY TO TUESDAY MORNING...
SQUALL LINE WILL PROBABLY WEAKEN WITH EWD EXTENT AS STRONGER DYNAMIC
FORCING WITH THE SHORT WAVE TROUGH AND SPEED MAX LIFT NEWD ACROSS
THE MISSOURI RIVER VALLEY AND LEAVE RESIDUAL WEAK NEAR-SURFACE-BASED
INSTABILITY BEHIND ACROSS THE ARKLATEX. THE DAY5 OTLK AREA EXISTS
FOR THE POTENTIAL FOR DAMAGING WINDS WITH THE DECAYING SQUALL LINE
EARLY IN THE PERIOD. STORMS COULD ALSO PERSIST ALONG THIS AXIS
DURING THE DAY WHERE DEEP-LAYER SHEAR WILL BE QUITE STRONG AND MORE
THAN ADEQUATE FOR ORGANIZED/PERSISTENT UPDRAFTS/SUPERCELLS.
HOWEVER...THIS SCENARIO...IN THE PRESENCE OF WEAK SHORT WAVE RIDGING
NOW BEING FORECAST...APPEARS LESS LIKELY THAN IN EARLIER FORECASTS.
...DAY6-8/TUESDAY THROUGH FRIDAY...
THE SYSTEM CROSSING THE PLAINS THROUGH DAY5 MAY SET THE STAGE FOR A
MORE WIDESPREAD EPISODE OF SEVERE WEATHER OVER THE CNTRL U.S./MS
VALLEY REGIONS ON DAY7/WEDNESDAY. THIS COULD OCCUR AS A HIGHLY
AMPLIFIED AND FAST-MOVING SHORT WAVE TROUGH MOVES EAST FROM THE
PLAINS AND SUPPORTS THE DEVELOPMENT OF A STRONG SURFACE CYCLONE AND
COLD FRONT PER LATEST GFS. THIS NEXT SYSTEM WILL HAVE THE POTENTIAL
TO TAP INTO HIGHER MOISTURE/GREATER INSTABILITY BROUGHT ABOUT BY THE
ENHANCED RETURN FLOW LEFT IN THE WAKE OF MONDAY/S DISTURBANCE.
HOWEVER...A WIDE RANGE OF POSSIBLE SCENARIOS EXIST WITH THIS NEXT
SYSTEM AND THE LARGE SPREAD AMONGST ENSEMBLE MEMBERS...AS WELL AS
MAJOR DIFFERENCES IN ECMWF AND GFS FORECASTS...PRECLUDE MAKING A
RELIABLE SEVERE STORM FORECAST AT THIS TIME.
..CARBIN.. 02/05/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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