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000
FXUS63 KLSX 201149
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
649 AM CDT MON MAY 20 2013

.UPDATE...
ISSUED AT 640 AM CDT MON MAY 20 2013

LOW LEVEL JET CONTINUES TO FEED SHOWERS AND THUNDERSTORMS FROM
SOUTHEAST KANSAS THROUGH EASTERN MISSOURI THIS MORNING. BELIEVE
THE EASTERN EXTENT OF THIS ACTIVITY WILL DIMINISH WITH TIME AS
FOCUS SHIFTS WEST. SOME QUESTION AS TO WHETHER CONVECTION
DEVELOPING ACROSS SOUTHEAST KANSAS AND SOUTHWEST MISSOURI WILL
DIMINISH OR INTENSIFY AS PLUME OF STEEP MID LEVEL LAPSE RATES
CONTINUES TO FEED INTO THAT AREA FROM OKLAHOMA.

IF CONVECTION CONTINUES TO DEVLEOP TO OUR SOUTHWEST THE CURRENT
FORECAST WILL NEED TO BE ADJUSTED DRASTICALLY TO ACCOUNT FOR MORE
CLOUD COVER...PERSISTENT SHOWERS AND THUNDERSTORMS AND THEREFORE
COOLER HIGH TEMPERATURES. WILL CONTINUE TO MONITOR AND PASS ALONG
TO THE DAY SHIFT THESE CONCERNS.

CVKING

&&

.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 358 AM CDT MON MAY 20 2013

MORNING CONVECTION WILL CONTINUE TO MOVE EWD THRU THE CWA EARLY
THIS MORNING. CURRENTLY DO NOT ANTICIPATE OUTFLOW FROM THIS
CONVECTION IMPACTING THE CWA LATER TODAY AS IT SHUD CONTINUE WELL
OUTSIDE OF THE CWA.

THE CDFNT CURRENTLY OVER ERN KS WILL MOVE EWD TODAY AND SHUD BE
JUST W OF THE CWA AROUND NOON. WITH THE ENTIRE AREA IN THE WARM
SECTOR...EXPECT AREA TO RECOVER WELL WITH AMPLE INSOLATION.
MDL SOLNS DIFFER REGARDING EXACTLY HOW TSRA WILL UNFOLD TODAY.
CONVECTION ALLOWING MDLS SUGGEST FOCUS WILL BE SW OF THE CWA THIS
AFTERNOON/EVE WITH THIS LINE MOVING NEWD INTO THE AREA LATE
TONIGHT. THE OPR MDLS SUGGEST TSRA WILL DEVELOP JUST AHEAD OF THE
CWA LATE THIS MORNING OR EARLY AFTERNOON. INTERESTINGLY...THE
LOCAL 4KM WRF PROVIDES A MERGER OF THESE TWO SOLNS...WHICH SEEMS
THE MOST LIKELY. WHILE TIMING REMAINS A QUESTION...WHAT DOES FORM
SHUD EVOLVE UPSCALE INTO A LINEAR MODE AS IT MOVES ACROSS THE
AREA. TSRA SHUD BE ON THE ERN EDGE OF THE CWA BY SUNRISE TUES.

LITTLE CHANGE WAS MADE TO TEMPS...KEEPING THE FORECAST AOA THE
WARMEST MOS.

TILLY

.LONG TERM...(MONDAY THROUGH NEXT SUNDAY)
ISSUED AT 331 PM CDT SUN MAY 19 2013

CURRENT INDICATIONS BASED ON THE DETERMINISTIC MODELS AND CONVECTION
ALLOWING MODELS IS THAT ANY THUNDERSTORMS REMAINING FROM THE OVERNIGHT
MCS SHOULD BE IN A DRASTICALLY WEAKENED STATE AT DAYBREAK. GIVEN THAT THE
PRIMARY SHORT WAVE TROF WILL HAVE ALREADY ROTATED NEWD INTO IOWA
AND A VEERED WSWLY LLJ...ANY REMAINING SHOWERS AND THUNDERSTORMS
WILL MOST LIKELY BE LOCATED FROM SOUTHWEST/SOUTH CENTRAL IL ACROSS
SE MO. THESE SHOULD DIMINISH BY MID MORNING AS LARGE SCALE SUBSIDENCE
OVERSPREADS THE REGION. IN THE WAKE OF THIS ACTIVITY AND GIVEN THE
TENDENCY TOWARDS CUMULIFORM CLOUDS...GOOD HEATING WILL COMMENCE.
THIS HEATING COMBINED WITH A MOIST BOUNDARY LAYER AND STEEP MID
LEVEL LAPSE RATES WILL CONTRIBUTE TO MODERATE-STRONG INSTABILITY
AND WEAK CONVECTIVE INHIBITION ACROSS THE ENTIRE AREA BY MID
AFTERNOON. SOUTHWESTERLY DEEP LAYER SHEAR AOA 40 KTS WOULD FAVOR
DISCRETE TO SEMI-DISCRETE SUPERCELLS AS THE DOMINATE STORM MODE
INITIALLY. AT THIS WE ARE EXPECTING A FAVORED WSW-ENE CORRIDOR
FOR STORM DEVELOPMENT AFTER 21Z FROM AROUND JEFFERSON CITY TO
BOWLING GREEN...ALTHO THIS AXIS COULD BE A BIT FURTHER SOUTH
DEPENDING ON ANY RESIDUAL BOUNDARIES. MERGERS AND ADDITIONAL
DEVELOPMENT WITHIN THIS ZONE AND UPSTREAM SHOULD RESULT IN A MIX
OF STORM MODES BY LATE AFTERNOON AND EVENING WITH POTENTIAL FOR
SUPERCELLS AND BOWING LINEAR SEGMENTS. THE OVERALL COVERAGE OF
STORMS SHOULD INCREASE DURING THE EVENING AS THE NEXT UPSTREAM
SHORT WAVE SPREADS LARGE SCALE ASCENT INTO THE REGION...ALSO
CONTRIBUTING TO UPSCALE STORM GROWTH. THERE EVENTUALLY COULD BE A
HEAVY RAIN THREAT FROM CENTRAL THROUGH EAST CENTRAL MO DUE TO
PERSISTENT AND TRAINING CONVECTION...BUT THE EXACT LOCATION IS TOO
DIFFICULT TO PINPOINT AT THIS POINT.

THE CONVECTIVE DETAILS BECOME LESS DEFINED ON TUESDAY DUE TO THE
POTENTIAL FOR RESIDUAL SHOWERS/STORMS FROM MONDAY NIGHT AND THE
PRESENCE OF MESOSCALE BOUNDARIES. THE OVERALL SYNOPTIC PATTERN
FEATURING THE UPPER TROF PROGRESSING EASTWARD WITH THE ATTENDANT
COLD FRONT MOVING THRU THE CWA DURING THE LATE AFTERNOON/EVENING
WOULD FAVOR HIGH THUNDERSTORM CHANCES...ESPECIALLY THE SE HALF OF
THE CWA. DEEP LAYER SHEAR OF 30-40 KTS AND WEAK-MODERATE INSTABILITY
WOULD CONTINUE TO FAVOR ORGANIZED-MIXED MODE SEVERE STORMS.

THE BOUNDARY FINALLY LOOKS TO PASS SOUTH OF THE AREA BY LATE
WEDNESDAY WITH ANOTHER REINFORCING BOUNDARY ON THURSDAY. THE PATTERN
THEN IS DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF THE UPPER TROF
AND LOOKS DRY THURSDAY NIGHT-SAT MORNING. THEREAFTER RETURN FLOW AND
WEAK DISTURBANCES PASSING THRU THE PLAINS UPPER RIDGE AND INTO THE
MID/UPPER MS VALLEY WILL BRING A RE-NEWED CHANCE OF
THUNDERSTORMS....ESPECIALLY THE NRN HALF OF THE CWA.

GLASS

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 640 AM CDT MON MAY 20 2013

CURRENTLY RADAR DEPICTS A LINE OF SHOWER AND THUNDERSTORMS
STRECHING ACROSS THE ST. LOUIS METRO AREA. THIS LINE SHOULD
CONTINUE TO PUSH EAST AND DISSIPATE THIS MORNING. SOME QUESTION TO
CONVECTIVE TRENDS THIS MORNING AND INTO THE AFTERNOON AS LOW LEVEL
JET CONTINUES TO DEVELOP THUNDERSTORMS ALL THE WAY BACK INTO
SOUTHEAST KANSAS/SOUTHWEST MISSOURI. THOUGH THIS ACTIVITY WOULD BE
DIMINISHING BY THIS POINT IN THE MORNING...BUT UNSTABLE CONDITIONS
TO OUR SOUTHWEST COULD KEEP THIS CONVECTION DEVELOPING AND MOVING
NORTHEAST ACROSS THE FORECAST AREA THIS MORNING. WILL CONTINUE TO
MONITOR AND UPDATE AS NECESSARY. OTHERWISE...EXPECT ADDITIONAL
THUNDERSTORMS TO DEVELOP THIS AFTERNOON AND EVENING. GIVEN
UNCERTAINTY HAVE OPTED TO JUST KEEP VCTS IN FORECAST UNTIL WE SEE
WHAT HAPPENS THIS MORNING. SOUTH WIND TO CONTINUE.

SPECIFICS FOR KSTL...
LINE OF SHOWERS AND THUNDERSTORMS MOVING THROUGH THE TERMINAL
COMPLEX AT THE MOMENT WILL MOVE EAST AND WEAKEN. WILL HAVE TO
MONITOR RADAR TRENDS OVER THE NEXT HOUR FOR THE NEED TO INCLUDE
ADDITIONAL HOURS OF RAIN/THUNDERSTORMS BASED ON DEVELOPMENT TO THE
SOUTHWEST. AT THIS POINT WOULD THINK THAT CONVECTION WOULD
DISSIPATE THIS MORNING...WITH REDEVELOPMENT THIS AFTERNOON.



CVKING

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&

$$

WFO LSX