000
FXUS63 KLSX 211129
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
629 AM CDT TUE MAY 21 2013
.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 348 AM CDT TUE MAY 21 2013
FOCUS THRU THIS PERIOD WILL BE TSRA CHANCES.
SFC ANALYSIS AT 07Z DEPICTS THE EFFECTIVE SFC BNDY ACROSS WRN IA
INTO NWRN MO...THEN EXTENDING SWWD INTO ERN KS. BELIEVE THIS IS SOME
SORT OF PRE-FRONTAL TROF/DRY LINE AS IT APPEARS THE ACTUAL SFC FNT
IS STILL ACROSS ERN NEB INTO WRN KS. THIS TROF/DRY LINE SHUD MOVE
EWD RATHER SLOWLY TODAY.
A NUMBER OF QUESTIONS REMAIN ABOUT TODAY GIVEN THE SPREAD AMONG MDL
SOLNS. EXPECT ONGOING PRECIP TO GRADUALLY MOVE EWD OUT OF THE CWA
LATER THIS MORNING. BELIEVE ISOD TO SCT TSRA WILL DEVELOP THIS
AFTERNOON ALONG THE TROF/DRY LINE. SETUP TODAY DOES NOT APPEAR AS
FAVORABLE FOR SEVERE WEATHER TODAY COMPARED TO YESTERDAY.
HOWEVER...BELIEVE THE GFS/NAM ARE UNDERPLAYING THE EVENT TODAY AND
TONIGHT FOR THE CWA.
MDLS PROG CONVECTION OVER ARKLATEX REGION THIS AFTERNOON/EVE LIFTING
NEWD TONIGHT INTO THE CWA. THIS TSRA WILL BE DRIVEN BY A VORT MAX
CURRENTLY OVER NRN NM/SRN CO REGION. MDLS TO SOME DEGREE...EXCEPT
FOR THE NAM...DEVELOP A SFC WAVE ALONG THE SFC TROF TONIGHT. THIS
LOW SHUD TRAVEL NEWD ALONG THE SFC TROF. THE ECMWF/LOCAL WRF HAVE A
MORE NWRN SOLN AND THIS SEEMS REASONABLE AS THESE MDLS HAVE A FAIRLY
GOOD HANDLE CURRENTLY ON THE STRENGTH OF THIS SYSTEM. IF THIS SOLN
VERIFIES...THIS LOW WILL PROVIDE ENHANCED SHEAR AS WELL AS ALLOW
STEEPER LAPSE RATES TO ADVECT INTO THE AREA. GIVEN PROGD HODOGRAPHS
AND TIMING...BELIEVE TSRA WILL BE LINEAR BY THE TIME THEY ENTER THE
CWA.
IF THIS NRN SOLN IS CORRECT...THE DAY SHIFT MAY NEED TO CONSIDER A
FLASH FLOOD WATCH FOR ERN PORTIONS OF THE CWA.
AS FOR TEMPS...TRENDED AOA WARMEST MOS FOR TODAY AND COOLER FOR
TONIGHT AS THE ACTUAL CDFNT FINALLY MOVES THRU THE AREA.
TILLY
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 440 AM CDT TUE MAY 21 2013
FOCUS STARTS TO SHIFT TO TEMPS AS PRECIP FINALLY MOVES E OF THE
AREA.
WITH FOCUS ON TODAY AND TONIGHT...ONLY MINOR CHANGES WERE MADE TO
THE PREV FORECAST AS MUCH OF IT STILL APPEARS TO BE ON TRACK. MDLS
ARE IN REMARKABLY GOOD AGREEMENT THRU THE PERIOD WRT MASS FIELDS.
UNCERTAINTY REMAINS FOR TEMPS ON WED/THURS. MDLS SUGGEST TEMPS
WILL STRUGGLE TO REACH 70S. HOWEVER...GIVEN THAT IT IS MAY...IF
ANY SUN MANAGES TO MAKE IT THRU THE CLOUDS...WUD BE SURPRISED IF
TEMPS DID NOT AT LEAST BRIEFLY REACH UPPER 70S OR INTO THE LOWER
80S. WITH UPPER RIDGE BUILDING INTO THE AREA ON SAT AND
BEYOND...TEMP FORECAST BECOMES MORE QUESTIONABLE WITH DIFFERING
SOLNS AT THE SFC. FOR NOW...MADE ONLY MINOR CHANGES...BUT BELIEVE
A TREND TWD THE GFS MAY BE NEEDED WITH A WARMER AND DRIER SOLN.
TILLY
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 617 AM CDT TUE MAY 21 2013
VFR CONDITIONS EXPECTED THIS MORNING AS OVERNIGHT CONVECTION HAS
SHIFTED SOUTH OF THE CWA. NEXT UPPER LEVEL DISTURBANCE CURRENTLY
CROSSING THE SOUTHERN PLAINS WILL LEAD TO AN INCREASE IN SHOWERS
AND THUNDERSTORMS AHEAD OF A SLOW MOVING COLD FRONT LATE THIS
AFTERNOON AND THIS EVENING. RAIN CHANCES TO FINALLY COME TO AN END
FOR TERMINALS AROUND SUNRISE WEDNESDAY AS THE COLD FRONT MOVES
EAST WITH WINDS SHIFTING FROM THE SOUTHWEST TO THE WEST.
SPECIFICS FOR KSTL...
VFR CONDITIONS EXPECTED THIS MORNING WITH THINNING CLOUD COVER.
SHOWERS AND THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE ONCE
AGAIN LATE THIS AFTERNOON AND EVENING...WITH COLD FRONTAL PASSAGE
BETWEEN 09Z AND 12Z.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 211028
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
528 AM CDT TUE MAY 21 2013
.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 348 AM CDT TUE MAY 21 2013
FOCUS THRU THIS PERIOD WILL BE TSRA CHANCES.
SFC ANALYSIS AT 07Z DEPICTS THE EFFECTIVE SFC BNDY ACROSS WRN IA
INTO NWRN MO...THEN EXTENDING SWWD INTO ERN KS. BELIEVE THIS IS SOME
SORT OF PRE-FRONTAL TROF/DRY LINE AS IT APPEARS THE ACTUAL SFC FNT
IS STILL ACROSS ERN NEB INTO WRN KS. THIS TROF/DRY LINE SHUD MOVE
EWD RATHER SLOWLY TODAY.
A NUMBER OF QUESTIONS REMAIN ABOUT TODAY GIVEN THE SPREAD AMONG MDL
SOLNS. EXPECT ONGOING PRECIP TO GRADUALLY MOVE EWD OUT OF THE CWA
LATER THIS MORNING. BELIEVE ISOD TO SCT TSRA WILL DEVELOP THIS
AFTERNOON ALONG THE TROF/DRY LINE. SETUP TODAY DOES NOT APPEAR AS
FAVORABLE FOR SEVERE WEATHER TODAY COMPARED TO YESTERDAY.
HOWEVER...BELIEVE THE GFS/NAM ARE UNDERPLAYING THE EVENT TODAY AND
TONIGHT FOR THE CWA.
MDLS PROG CONVECTION OVER ARKLATEX REGION THIS AFTERNOON/EVE LIFTING
NEWD TONIGHT INTO THE CWA. THIS TSRA WILL BE DRIVEN BY A VORT MAX
CURRENTLY OVER NRN NM/SRN CO REGION. MDLS TO SOME DEGREE...EXCEPT
FOR THE NAM...DEVELOP A SFC WAVE ALONG THE SFC TROF TONIGHT. THIS
LOW SHUD TRAVEL NEWD ALONG THE SFC TROF. THE ECMWF/LOCAL WRF HAVE A
MORE NWRN SOLN AND THIS SEEMS REASONABLE AS THESE MDLS HAVE A FAIRLY
GOOD HANDLE CURRENTLY ON THE STRENGTH OF THIS SYSTEM. IF THIS SOLN
VERIFIES...THIS LOW WILL PROVIDE ENHANCED SHEAR AS WELL AS ALLOW
STEEPER LAPSE RATES TO ADVECT INTO THE AREA. GIVEN PROGD HODOGRAPHS
AND TIMING...BELIEVE TSRA WILL BE LINEAR BY THE TIME THEY ENTER THE
CWA.
IF THIS NRN SOLN IS CORRECT...THE DAY SHIFT MAY NEED TO CONSIDER A
FLASH FLOOD WATCH FOR ERN PORTIONS OF THE CWA.
AS FOR TEMPS...TRENDED AOA WARMEST MOS FOR TODAY AND COOLER FOR
TONIGHT AS THE ACTUAL CDFNT FINALLY MOVES THRU THE AREA.
TILLY
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 440 AM CDT TUE MAY 21 2013
FOCUS STARTS TO SHIFT TO TEMPS AS PRECIP FINALLY MOVES E OF THE
AREA.
WITH FOCUS ON TODAY AND TONIGHT...ONLY MINOR CHANGES WERE MADE TO
THE PREV FORECAST AS MUCH OF IT STILL APPEARS TO BE ON TRACK. MDLS
ARE IN REMARKABLY GOOD AGREEMENT THRU THE PERIOD WRT MASS FIELDS.
UNCERTAINTY REMAINS FOR TEMPS ON WED/THURS. MDLS SUGGEST TEMPS
WILL STRUGGLE TO REACH 70S. HOWEVER...GIVEN THAT IT IS MAY...IF
ANY SUN MANAGES TO MAKE IT THRU THE CLOUDS...WUD BE SURPRISED IF
TEMPS DID NOT AT LEAST BRIEFLY REACH UPPER 70S OR INTO THE LOWER
80S. WITH UPPER RIDGE BUILDING INTO THE AREA ON SAT AND
BEYOND...TEMP FORECAST BECOMES MORE QUESTIONABLE WITH DIFFERING
SOLNS AT THE SFC. FOR NOW...MADE ONLY MINOR CHANGES...BUT BELIEVE
A TREND TWD THE GFS MAY BE NEEDED WITH A WARMER AND DRIER SOLN.
TILLY
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1241 AM CDT TUE MAY 21 2013
ACTIVE/MOST INTENSE CONVECTION HAS BEEN RIDING OUTFLOW BOUNDARY
OVER THE LAST FEW HOURS...AND IS NOW IN THE PROCESS OF EXITING OUR
CWA. HAVE CONTINUED SHOWERS IN THE WAKE OF THE MOST INTENSE
CONVECTION FOR SEVERAL MORE HOURS IN STL AREA AS ELEVATED PRECIP
CONTINUES TO PERCOLATE OVER S CENTRAL MO AND MOVE NE. ITS
CERTAINLY POSSIBLE THAT RESDIUAL INSTABILITY AND INCREASING
SOUTHERLY FLOW OVERNIGHT COULD REFIRE ELEVATED CONVECTION...BUT
FOR THE TIME BEING HAVE HELD STORMS OUT OF ALL TAFS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. TAFS FOR THE REMAINDER OF THE
NIGHT WILL GENERALLY TREND TO VFR WITH CIGS AOA 8KFT...BUT WILL
CERTAINLY NEED TO WATCH FOR THE DEVELOPMENT OF SOME STRATUS
DURING THE PREDAWN HOURS. HAVE NOT MADE ANY SIGNIFICANT CHANGES
TO TUESDAYS TRENDS...WITH THE REINTRODUCTION OF TSRA BY EARLY/MID
AFTERNOON.
SPECIFICS FOR KSTL...CIGS AOA 8KFT SHOULD BE THE RULE DURING THE
PREDAWN HOURS...WITH A FEW LINGERING SHOWERS STILL POSSIBLE
THROUGH 08Z. SHOULD SEE A BIT OF CU FORM BY MID MORNING...FOLLOWED
BY A THREAT OF THUNDERSTORMS BY MID AFTERNOON.
TRUETT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 210849
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
349 AM CDT TUE MAY 21 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 348 AM CDT TUE MAY 21 2013
FOCUS THRU THIS PERIOD WILL BE TSRA CHANCES.
SFC ANALYSIS AT 07Z DEPICTS THE EFFECTIVE SFC BNDY ACROSS WRN IA
INTO NWRN MO...THEN EXTENDING SWWD INTO ERN KS. BELIEVE THIS IS SOME
SORT OF PRE-FRONTAL TROF/DRY LINE AS IT APPEARS THE ACTUAL SFC FNT
IS STILL ACROSS ERN NEB INTO WRN KS. THIS TROF/DRY LINE SHUD MOVE
EWD RATHER SLOWLY TODAY.
A NUMBER OF QUESTIONS REMAIN ABOUT TODAY GIVEN THE SPREAD AMONG MDL
SOLNS. EXPECT ONGOING PRECIP TO GRADUALLY MOVE EWD OUT OF THE CWA
LATER THIS MORNING. BELIEVE ISOD TO SCT TSRA WILL DEVELOP THIS
AFTERNOON ALONG THE TROF/DRY LINE. SETUP TODAY DOES NOT APPEAR AS
FAVORABLE FOR SEVERE WEATHER TODAY COMPARED TO YESTERDAY.
HOWEVER...BELIEVE THE GFS/NAM ARE UNDERPLAYING THE EVENT TODAY AND
TONIGHT FOR THE CWA.
MDLS PROG CONVECTION OVER ARKLATEX REGION THIS AFTERNOON/EVE LIFTING
NEWD TONIGHT INTO THE CWA. THIS TSRA WILL BE DRIVEN BY A VORT MAX
CURRENTLY OVER NRN NM/SRN CO REGION. MDLS TO SOME DEGREE...EXCEPT
FOR THE NAM...DEVELOP A SFC WAVE ALONG THE SFC TROF TONIGHT. THIS
LOW SHUD TRAVEL NEWD ALONG THE SFC TROF. THE ECMWF/LOCAL WRF HAVE A
MORE NWRN SOLN AND THIS SEEMS REASONABLE AS THESE MDLS HAVE A FAIRLY
GOOD HANDLE CURRENTLY ON THE STRENGTH OF THIS SYSTEM. IF THIS SOLN
VERIFIES...THIS LOW WILL PROVIDE ENHANCED SHEAR AS WELL AS ALLOW
STEEPER LAPSE RATES TO ADVECT INTO THE AREA. GIVEN PROGD HODOGRAPHS
AND TIMING...BELIEVE TSRA WILL BE LINEAR BY THE TIME THEY ENTER THE
CWA.
IF THIS NRN SOLN IS CORRECT...THE DAY SHIFT MAY NEED TO CONSIDER A
FLASH FLOOD WATCH FOR ERN PORTIONS OF THE CWA.
AS FOR TEMPS...TRENDED AOA WARMEST MOS FOR TODAY AND COOLER FOR
TONIGHT AS THE ACTUAL CDFNT FINALLY MOVES THRU THE AREA.
TILLY
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY)
ISSUED AT 323 PM CDT MON MAY 20 2013
THE IMPACTS OF THE OVERNIGHT CONVECTION ARE HARD TO GAGE AND WILL
HAVE LARGE RAMIFICATIONS ON THE THUNDERSTORM AND SEVERE THREAT
TUESDAY. ANY ONGOING SHOWERS/THUNDERSTORMS REMNANT FROM OVERNIGHT
ARE LIKELY TO BE LOCATED ACROSS SE MO INTO SW IL DURING THE FIRST
PART OF THE MORNING AND THEN WEAKEN. MODEL GUIDANCE SUGGESTS IT
WILL THEN REMAIN RELATIVELY VOID OF PRECIPITATION WELL INTO MID
AFTERNOON AND THIS SHOULD ALLOW FOR SOME AIR MASS RECOVERY AS
CLOUDS THIN. MID LEVEL LAPSE RATES ARE NOT AS STEEP SO OVERALL
INSTABILITY SHOULD BE LESS THAN THE LAST FEW DAYS...HOWEVER IT SHOULD
BE SUFFICIENT WITH AMPLE DEEP LAYER SHEAR FOR SCATTERED ORGANIZED
THUNDERSTORMS DEVELOPING DURING THE LATER PART OF THE AFTERNOON...RAMPING
UP IN COVERAGE DURING THE EARLY EVENING AS LARGE SCALE ASCENT INCREASES
IN ASSOCIATION WITH A SHORT WAVE ROTATING NEWD FROM EASTERN OK
REGION. ANY RESIDUAL BOUNDARIES WILL PROVIDE FURTHER FOCUS AND
ENHANCE THE SEVERE THREAT. THE LARGE SCALE TROF AND ATTENDANT COLD
FRONT WILL FINALLY MOVE ACROSS THE AREA TUESDAY NIGHT...PASSING
EAST OF THE CWA BY EARLY WEDNESDAY MORNING. DRIER AIR AND COOLER
AIR WILL OVERSPREAD THE AREA ON WEDNESDAY IN THE WAKE OF THE FRONT
AND A SECONDARY COLD FRONT ON WEDNESDAY NIGHT WILL USHER EVEN
COOLER AIR AND HIGH PRESSURE INTO THE AREA.
THE PATTERN WILL BE DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF
THE UPPER TROF AND LOOKS DRY THURSDAY NIGHT-FRIDAY...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.
WARMER TEMPERATURES WILL ALSO ACCOMPANY THE RETURN FLOW.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1241 AM CDT TUE MAY 21 2013
ACTIVE/MOST INTENSE CONVECTION HAS BEEN RIDING OUTFLOW BOUNDARY
OVER THE LAST FEW HOURS...AND IS NOW IN THE PROCESS OF EXITING OUR
CWA. HAVE CONTINUED SHOWERS IN THE WAKE OF THE MOST INTENSE
CONVECTION FOR SEVERAL MORE HOURS IN STL AREA AS ELEVATED PRECIP
CONTINUES TO PERCOLATE OVER S CENTRAL MO AND MOVE NE. ITS
CERTAINLY POSSIBLE THAT RESDIUAL INSTABILITY AND INCREASING
SOUTHERLY FLOW OVERNIGHT COULD REFIRE ELEVATED CONVECTION...BUT
FOR THE TIME BEING HAVE HELD STORMS OUT OF ALL TAFS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. TAFS FOR THE REMAINDER OF THE
NIGHT WILL GENERALLY TREND TO VFR WITH CIGS AOA 8KFT...BUT WILL
CERTAINLY NEED TO WATCH FOR THE DEVELOPMENT OF SOME STRATUS
DURING THE PREDAWN HOURS. HAVE NOT MADE ANY SIGNIFICANT CHANGES
TO TUESDAYS TRENDS...WITH THE REINTRODUCTION OF TSRA BY EARLY/MID
AFTERNOON.
SPECIFICS FOR KSTL...CIGS AOA 8KFT SHOULD BE THE RULE DURING THE
PREDAWN HOURS...WITH A FEW LINGERING SHOWERS STILL POSSIBLE
THROUGH 08Z. SHOULD SEE A BIT OF CU FORM BY MID MORNING...FOLLOWED
BY A THREAT OF THUNDERSTORMS BY MID AFTERNOON.
TRUETT
&&
.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS 85 62 79 57 / 70 80 20 10
QUINCY 80 58 72 54 / 40 40 20 10
COLUMBIA 80 56 73 54 / 40 40 10 10
JEFFERSON CITY 81 58 75 55 / 50 50 10 10
SALEM 84 64 79 57 / 70 80 40 10
FARMINGTON 81 61 78 56 / 70 80 20 10
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 210556
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1256 AM CDT TUE MAY 21 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 323 PM CDT MON MAY 20 2013
ALL SYSTEMS APPEAR GO FOR AN ACTIVE NIGHT OF THUNDERSTORMS WITH
SEVERE POTENTIAL AS THE ENVIRONMENT WILL HAVE PLENTY OF INSTABILITY
AND DEEP LAYER SHEAR AROUND 50 KTS. THE AIR MASS OVER THE SOUTHERN
HALF OF MISSOURI HAS RECOVERED FROM EARLIER CONVECTION WITH SBCAPE
AOA 3000 J/KG AND THIS RECOVERY SHOULD CONTINUE TO SPREAD
NORTHWARD THROUGH THE LATE AFTERNOON. SCATTERED THUNDERSTORMS HAVE
DEVELOPED IN SEVERAL CONFLUENT ZONES ACROSS SW MO AND SE KS AND
ARE MOVING TO THE NORTHEAST. ADDITIONAL DEVELOPMENT IS EXPECTED
WITH DISCRETE STORMS POSSIBLE THROUGH EARLY EVENING AND THEN AN
OVERALL TREND FOR RAPID UPSCALE GROWTH INTO A FORWARD PROPAGATING
QLCS FEATURING A MIX MODE OF BOWING SEGMENTS AND EMBEDDED
SUPERCELLS. THIS QLCS IS EXPECTED TO IMPACT A GOOD PORTION OF THE
CWA AS IT MOVES E/NW TONIGHT. SOME LOCALLY HEAVY RAINFALL MAY
OCCUR WHERE TRAINING OCCURS...BUT THE SYSTEM IS NOT EXPECTED TO
PRODUCE A WIDESPREAD HEAVY RAIN/FLASH FLOOD THREAT.
GLASS
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY)
ISSUED AT 323 PM CDT MON MAY 20 2013
THE IMPACTS OF THE OVERNIGHT CONVECTION ARE HARD TO GAGE AND WILL
HAVE LARGE RAMIFICATIONS ON THE THUNDERSTORM AND SEVERE THREAT
TUESDAY. ANY ONGOING SHOWERS/THUNDERSTORMS REMNANT FROM OVERNIGHT
ARE LIKELY TO BE LOCATED ACROSS SE MO INTO SW IL DURING THE FIRST
PART OF THE MORNING AND THEN WEAKEN. MODEL GUIDANCE SUGGESTS IT
WILL THEN REMAIN RELATIVELY VOID OF PRECIPITATION WELL INTO MID
AFTERNOON AND THIS SHOULD ALLOW FOR SOME AIR MASS RECOVERY AS
CLOUDS THIN. MID LEVEL LAPSE RATES ARE NOT AS STEEP SO OVERALL
INSTABILITY SHOULD BE LESS THAN THE LAST FEW DAYS...HOWEVER IT SHOULD
BE SUFFICIENT WITH AMPLE DEEP LAYER SHEAR FOR SCATTERED ORGANIZED
THUNDERSTORMS DEVELOPING DURING THE LATER PART OF THE AFTERNOON...RAMPING
UP IN COVERAGE DURING THE EARLY EVENING AS LARGE SCALE ASCENT INCREASES
IN ASSOCIATION WITH A SHORT WAVE ROTATING NEWD FROM EASTERN OK
REGION. ANY RESIDUAL BOUNDARIES WILL PROVIDE FURTHER FOCUS AND
ENHANCE THE SEVERE THREAT. THE LARGE SCALE TROF AND ATTENDANT COLD
FRONT WILL FINALLY MOVE ACROSS THE AREA TUESDAY NIGHT...PASSING
EAST OF THE CWA BY EARLY WEDNESDAY MORNING. DRIER AIR AND COOLER
AIR WILL OVERSPREAD THE AREA ON WEDNESDAY IN THE WAKE OF THE FRONT
AND A SECONDARY COLD FRONT ON WEDNESDAY NIGHT WILL USHER EVEN
COOLER AIR AND HIGH PRESSURE INTO THE AREA.
THE PATTERN WILL BE DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF
THE UPPER TROF AND LOOKS DRY THURSDAY NIGHT-FRIDAY...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.
WARMER TEMPERATURES WILL ALSO ACCOMPANY THE RETURN FLOW.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1241 AM CDT TUE MAY 21 2013
ACTIVE/MOST INTENSE CONVECTION HAS BEEN RIDING OUTFLOW BOUNDARY
OVER THE LAST FEW HOURS...AND IS NOW IN THE PROCESS OF EXITING OUR
CWA. HAVE CONTINUED SHOWERS IN THE WAKE OF THE MOST INTENSE
CONVECTION FOR SEVERAL MORE HOURS IN STL AREA AS ELEVATED PRECIP
CONTINUES TO PERCOLATE OVER S CENTRAL MO AND MOVE NE. ITS
CERTAINLY POSSIBLE THAT RESDIUAL INSTABILITY AND INCREASING
SOUTHERLY FLOW OVERNIGHT COULD REFIRE ELEVATED CONVECTION...BUT
FOR THE TIME BEING HAVE HELD STORMS OUT OF ALL TAFS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. TAFS FOR THE REMAINDER OF THE
NIGHT WILL GENERALLY TREND TO VFR WITH CIGS AOA 8KFT...BUT WILL
CERTAINLY NEED TO WATCH FOR THE DEVELOPMENT OF SOME STRATUS
DURING THE PREDAWN HOURS. HAVE NOT MADE ANY SIGNIFICANT CHANGES
TO TUESDAYS TRENDS...WITH THE REINTRODUCTION OF TSRA BY EARLY/MID
AFTERNOON.
SPECIFICS FOR KSTL...CIGS AOA 8KFT SHOULD BE THE RULE DURING THE
PREDAWN HOURS...WITH A FEW LINGERING SHOWERS STILL POSSIBLE
THROUGH 08Z. SHOULD SEE A BIT OF CU FORM BY MID MORNING...FOLLOWED
BY A THREAT OF THUNDERSTORMS BY MID AFTERNOON.
TRUETT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 202052
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
352 PM CDT MON MAY 20 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 323 PM CDT MON MAY 20 2013
ALL SYSTEMS APPEAR GO FOR AN ACTIVE NIGHT OF THUNDERSTORMS WITH
SEVERE POTENTIAL AS THE ENVIRONMENT WILL HAVE PLENTY OF INSTABILITY
AND DEEP LAYER SHEAR AROUND 50 KTS. THE AIR MASS OVER THE SOUTHERN
HALF OF MISSOURI HAS RECOVERED FROM EARLIER CONVECTION WITH SBCAPE
AOA 3000 J/KG AND THIS RECOVERY SHOULD CONTINUE TO SPREAD
NORTHWARD THROUGH THE LATE AFTERNOON. SCATTERED THUNDERSTORMS HAVE
DEVELOPED IN SEVERAL CONFLUENT ZONES ACROSS SW MO AND SE KS AND
ARE MOVING TO THE NORTHEAST. ADDITIONAL DEVELOPMENT IS EXPECTED
WITH DISCRETE STORMS POSSIBLE THROUGH EARLY EVENING AND THEN AN
OVERALL TREND FOR RAPID UPSCALE GROWTH INTO A FORWARD PROPAGATING
QLCS FEATURING A MIX MODE OF BOWING SEGMENTS AND EMBEDDED
SUPERCELLS. THIS QLCS IS EXPECTED TO IMPACT A GOOD PORTION OF THE
CWA AS IT MOVES E/NW TONIGHT. SOME LOCALLY HEAVY RAINFALL MAY
OCCUR WHERE TRAINING OCCURS...BUT THE SYSTEM IS NOT EXPECTED TO
PRODUCE A WIDESPREAD HEAVY RAIN/FLASH FLOOD THREAT.
GLASS
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY)
ISSUED AT 323 PM CDT MON MAY 20 2013
THE IMPACTS OF THE OVERNIGHT CONVECTION ARE HARD TO GAGE AND WILL
HAVE LARGE RAMIFICATIONS ON THE THUNDERSTORM AND SEVERE THREAT
TUESDAY. ANY ONGOING SHOWERS/THUNDERSTORMS REMNANT FROM OVERNIGHT
ARE LIKELY TO BE LOCATED ACROSS SE MO INTO SW IL DURING THE FIRST
PART OF THE MORNING AND THEN WEAKEN. MODEL GUIDANCE SUGGESTS IT
WILL THEN REMAIN RELATIVELY VOID OF PRECIPITATION WELL INTO MID
AFTERNOON AND THIS SHOULD ALLOW FOR SOME AIR MASS RECOVERY AS
CLOUDS THIN. MID LEVEL LAPSE RATES ARE NOT AS STEEP SO OVERALL
INSTABILITY SHOULD BE LESS THAN THE LAST FEW DAYS...HOWEVER IT SHOULD
BE SUFFICIENT WITH AMPLE DEEP LAYER SHEAR FOR SCATTERED ORGANIZED
THUNDERSTORMS DEVELOPING DURING THE LATER PART OF THE AFTERNOON...RAMPING
UP IN COVERAGE DURING THE EARLY EVENING AS LARGE SCALE ASCENT INCREASES
IN ASSOCIATION WITH A SHORT WAVE ROTATING NEWD FROM EASTERN OK
REGION. ANY RESIDUAL BOUNDARIES WILL PROVIDE FURTHER FOCUS AND
ENHANCE THE SEVERE THREAT. THE LARGE SCALE TROF AND ATTENDANT COLD
FRONT WILL FINALLY MOVE ACROSS THE AREA TUESDAY NIGHT...PASSING
EAST OF THE CWA BY EARLY WEDNESDAY MORNING. DRIER AIR AND COOLER
AIR WILL OVERSPREAD THE AREA ON WEDNESDAY IN THE WAKE OF THE FRONT
AND A SECONDARY COLD FRONT ON WEDNESDAY NIGHT WILL USHER EVEN
COOLER AIR AND HIGH PRESSURE INTO THE AREA.
THE PATTERN WILL BE DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF
THE UPPER TROF AND LOOKS DRY THURSDAY NIGHT-FRIDAY...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.
WARMER TEMPERATURES WILL ALSO ACCOMPANY THE RETURN FLOW.
GLASS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 112 PM CDT MON MAY 20 2013
STILL HARD TO PIN DOWN EXACT COVERAGE AND TIMING OF STORMS...SO
KEPT VCTS MENTION AT KCOU THROUGH 03Z TUESDAY AND THROUGH 04Z
TUESDAY AT KUIN. FURTHER EAST OVER STL METRO AREA...HRRR MODEL
INDICATING STORMS TO NOT MOVE IN TIL AFTER 01Z TUESDAY...MAYBE
EVEN LATER...BUT KEPT VCTS MENTION AFTER 01Z TUESDAY FOR
NOW...TAPERING OFF AFTER 07Z TUESDAY. OTHERWISE...EXPECT VFR CIGS AND
GUSTY SOUTH WINDS FOR THIS AFTERNOON...BEFORE DIMINISHING AFTER
SUNSET.
SPECIFICS FOR KSTL...STILL HARD TO PIN DOWN EXACT COVERAGE AND
TIMING OF STORMS...LATEST HRRR MODEL INDICATING STORMS TO NOT MOVE
IN TIL AFTER 04Z TUESDAY...MAYBE EVEN LATER...BUT KEPT VCTS
MENTION AFTER 01Z TUESDAY FOR NOW AS WE COULD SEE STUFF FIRE UP
AHEAD OF MAIN ACTIVITY. STORMS TO TAPER OFF AFTER 07Z TUESDAY.
OTHERWISE...EXPECT VFR CIGS AND GUSTY SOUTH WINDS FOR THIS
AFTERNOON...BEFORE DIMINISHING AFTER SUNSET. ANOTHER ROUND OF
STORMS POSSIBLE AFTER 21Z TUESDAY...SO ADDED VCTS MENTION DURING
THIS PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 201812
AFDLSX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
112 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 112 PM CDT MON MAY 20 2013
TORNADO WATCH ISSUED FOR PORTIONS OF CENTRAL MO...SO UPDATED
ZONES/GRIDS FOR THIS. MORNING ACTIVITY FINALLY EXITING FAR
NORTHEAST PORTIONS OF FORECAST AREA. TIMING OF NEXT ROUND TO BE
LATER THIS AFTERNOON OVER CENTRAL MO AND CONTINUE INTO THIS
EVENING. WITH CLOUDS CLEARING OUT...TEMPERATURES ARE FINALLY
RECOVERING WITH HIGHS IN THE 80S...THOUGH UPPER 70S EXPECTED FAR
NORTH DUE TO EXITING STORMS/CLOUDS.
BYRD
&&
.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 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 112 PM CDT MON MAY 20 2013
STILL HARD TO PIN DOWN EXACT COVERAGE AND TIMING OF STORMS...SO
KEPT VCTS MENTION AT KCOU THROUGH 03Z TUESDAY AND THROUGH 04Z
TUESDAY AT KUIN. FURTHER EAST OVER STL METRO AREA...HRRR MODEL
INDICATING STORMS TO NOT MOVE IN TIL AFTER 01Z TUESDAY...MAYBE
EVEN LATER...BUT KEPT VCTS MENTION AFTER 01Z TUESDAY FOR
NOW...TAPERING OFF AFTER 07Z TUESDAY. OTHERWISE...EXPECT VFR CIGS AND
GUSTY SOUTH WINDS FOR THIS AFTERNOON...BEFORE DIMINISHING AFTER
SUNSET.
SPECIFICS FOR KSTL...STILL HARD TO PIN DOWN EXACT COVERAGE AND
TIMING OF STORMS...LATEST HRRR MODEL INDICATING STORMS TO NOT MOVE
IN TIL AFTER 04Z TUESDAY...MAYBE EVEN LATER...BUT KEPT VCTS
MENTION AFTER 01Z TUESDAY FOR NOW AS WE COULD SEE STUFF FIRE UP
AHEAD OF MAIN ACTIVITY. STORMS TO TAPER OFF AFTER 07Z TUESDAY.
OTHERWISE...EXPECT VFR CIGS AND GUSTY SOUTH WINDS FOR THIS
AFTERNOON...BEFORE DIMINISHING AFTER SUNSET. ANOTHER ROUND OF
STORMS POSSIBLE AFTER 21Z TUESDAY...SO ADDED VCTS MENTION DURING
THIS PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
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
000
FXUS63 KLSX 200937
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
437 AM CDT MON MAY 20 2013
.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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 105 AM CDT MON MAY 20 2013
LINE OF TSRA WILL TAKE MUCH OF THE NIGHT TO WORK ITS WAY THRU THE
FA AND SHOULD AFFECT ALL TAF SITES BEFORE SUNRISE. UNCLEAR WHETHER
THERE WILL BE A BREAK BETWEEN THIS AND WHAT DEVELOPS UPSTREAM FROM
IT LATER ON MONDAY...BUT FOR NOW...HAVE FORECASTED THE TAFS AS IF
THERE WILL BE. THE SECOND...STRONGER ROUND...SHOULD GET GOING BY
EARLY AFTERNOON AND SLOWLY EXPAND SEWD. NOT ENTIRELY CERTAIN WHERE
THIS WILL HIT WITHOUT A CLEAR FEATURE TO FOLLOW AND THUS HAVE
GONE VCTS FOR NOW BUT WILL LIKELY HAVE TO RAMP UP THE FORECAST AT
SOME OF THE TERMINALS. S SFC WNDS WILL CONTINUE THRU THE PERIOD
BECOMING GUSTY ESPECIALLY DURING THE DAY ON MONDAY.
SPECIFICS FOR KSTL...VFR CONDITIONS EXPECTED OUTSIDE OF TSRA...ONE
ROUND OF TSRA FOR LATE TONIGHT...ANOTHER ROUND OF TSRA FOR LATER
ON MONDAY. RIGHT NOW IT APPEARS THE SECOND ROUND OF TSRA WILL NOT
WORK INTO THE TERMINAL AREA UNTIL EARLY EVENING AFTER AFFECTING
AREAS JUST TO THE NW AND THEN STAY FOR A WHILE.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 200604
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
104 AM CDT MON MAY 20 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 331 PM CDT SUN MAY 19 2013
FOCUS FOR STORMS EARLY THIS EVENING IS BACK OVER EASTERN KS/WESTERN
MO...THEN HAVE THIS COMPLEX OF STORMS MOVE EAST INTO
CENTRAL/NORTHEAST MO BY 03Z. STILL SOME UNCERTAINTY ON EXACT
PLACEMENT AND STRENGTH OF STORMS AS THEY MOVE EAST INTO FORECAST
AREA. 12Z MODELS ALL OVER THE PLACE WITH SOME FOCUSING MAIN AREA OF
STORMS ALONG AND SOUTH OF I-70...WHILE OTHERS HAVE A LONG LINE OF
STORMS MOVE ACROSS ENTIRE FORECAST AREA. FOR NOW HAVE AREA OF STORMS
MOVE ACROSS REGION...GRADUALLY WEAKENING/DIMINISHING TOWARDS
DAYBREAK...GOING FROM LIKELY POPS DOWN TO JUST CHANCE POPS BY 11Z.
BEST CHANCES WILL BE OVER WESTERN HALF OF FORECAST AREA. AS FOR
SEVERE WEATHER CHANCES...DECENT CAPES/PWS...LOW LEVEL JET...AND
SHORTWAVE SLIDING THROUGH AREA TONIGHT. SO WESTERN PORTIONS OF
FORECAST AREA STILL IN A SLIGHT RISK OVERNIGHT...WITH MAIN THREAT
BEING DAMAGING WINDS.
OTHERWISE...GUSTY SOUTHEAST TO SOUTH WINDS TO DIMINISH AFTER SUNSET.
MILD WEATHER TO PERSIST WITH LOWS ONLY IN THE MID TO UPPER
60S...WITH LOW 70S IN STL METRO AREA.
BYRD
.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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 105 AM CDT MON MAY 20 2013
LINE OF TSRA WILL TAKE MUCH OF THE NIGHT TO WORK ITS WAY THRU THE
FA AND SHOULD AFFECT ALL TAF SITES BEFORE SUNRISE. UNCLEAR WHETHER
THERE WILL BE A BREAK BETWEEN THIS AND WHAT DEVELOPS UPSTREAM FROM
IT LATER ON MONDAY...BUT FOR NOW...HAVE FORECASTED THE TAFS AS IF
THERE WILL BE. THE SECOND...STRONGER ROUND...SHOULD GET GOING BY
EARLY AFTERNOON AND SLOWLY EXPAND SEWD. NOT ENTIRELY CERTAIN WHERE
THIS WILL HIT WITHOUT A CLEAR FEATURE TO FOLLOW AND THUS HAVE
GONE VCTS FOR NOW BUT WILL LIKELY HAVE TO RAMP UP THE FORECAST AT
SOME OF THE TERMINALS. S SFC WNDS WILL CONTINUE THRU THE PERIOD
BECOMING GUSTY ESPECIALLY DURING THE DAY ON MONDAY.
SPECIFICS FOR KSTL...VFR CONDITIONS EXPECTED OUTSIDE OF TSRA...ONE
ROUND OF TSRA FOR LATE TONIGHT...ANOTHER ROUND OF TSRA FOR LATER
ON MONDAY. RIGHT NOW IT APPEARS THE SECOND ROUND OF TSRA WILL NOT
WORK INTO THE TERMINAL AREA UNTIL EARLY EVENING AFTER AFFECTING
AREAS JUST TO THE NW AND THEN STAY FOR A WHILE.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 192339
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
639 PM CDT SUN MAY 19 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 331 PM CDT SUN MAY 19 2013
FOCUS FOR STORMS EARLY THIS EVENING IS BACK OVER EASTERN KS/WESTERN
MO...THEN HAVE THIS COMPLEX OF STORMS MOVE EAST INTO
CENTRAL/NORTHEAST MO BY 03Z. STILL SOME UNCERTAINTY ON EXACT
PLACEMENT AND STRENGTH OF STORMS AS THEY MOVE EAST INTO FORECAST
AREA. 12Z MODELS ALL OVER THE PLACE WITH SOME FOCUSING MAIN AREA OF
STORMS ALONG AND SOUTH OF I-70...WHILE OTHERS HAVE A LONG LINE OF
STORMS MOVE ACROSS ENTIRE FORECAST AREA. FOR NOW HAVE AREA OF STORMS
MOVE ACROSS REGION...GRADUALLY WEAKENING/DIMINISHING TOWARDS
DAYBREAK...GOING FROM LIKELY POPS DOWN TO JUST CHANCE POPS BY 11Z.
BEST CHANCES WILL BE OVER WESTERN HALF OF FORECAST AREA. AS FOR
SEVERE WEATHER CHANCES...DECENT CAPES/PWS...LOW LEVEL JET...AND
SHORTWAVE SLIDING THROUGH AREA TONIGHT. SO WESTERN PORTIONS OF
FORECAST AREA STILL IN A SLIGHT RISK OVERNIGHT...WITH MAIN THREAT
BEING DAMAGING WINDS.
OTHERWISE...GUSTY SOUTHEAST TO SOUTH WINDS TO DIMINISH AFTER SUNSET.
MILD WEATHER TO PERSIST WITH LOWS ONLY IN THE MID TO UPPER
60S...WITH LOW 70S IN STL METRO AREA.
BYRD
.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 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 622 PM CDT SUN MAY 19 2013
A COUPLE OF LINES OF THUNDERSTORMS HAVE DEVELOPED ACROSS EASTERN
KS AND WRN MO EARLY THIS EVENING. THESE THUNDERSTORM COMPLEXES
WILL MOVE EWD OVER THE NEXT SEVERAL HOURS AND EVENTUALLY REACH
KCOU AND KUIN. IT IS UNCLEAR WHETHER THE STORMS WILL HOLD TOGETHER
LONG ENOUGH TO REACH THE KSTL METRO AREA. ANOTHER ROUND OF STORMS
IS EXPECTED TOMORROW AFTN/EVENING AS AN UPPER LEVEL DISTURBANCE
APPROACHES THE AREA AHEAD OF A SLOW-MOVING COLD FRONT. PREVAILING
WINDS OUTSIDE OF THUNDERSTORMS WILL GENERALLY RETAIN A SLY
COMPONENT...VARYING FM SELY TO SWLY WITH GUSTS TO 20-25 KTS AT
TIMES. BRIEF PDS OF IFR CONDITIONS ARE EXPECTED IN THUNDERSTORMS.
SPECIFICS FOR KSTL...A COUPLE OF THUNDERSTORM COMPLEXES HAVE
DEVELOPED AND ARE EXPECTED TO MOVE EWD TONIGHT HOWEVER IT IS
UNCLEAR ATTM WHETHER THE STORMS WILL HOLD TOGETHER LONG ENOUGH TO
REACH KSTL. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TOMORROW
AFTN/EVENING AHEAD OF A SLOW-MOVING CDFNT. PREVAILING WINDS
OUTSIDE OF THUNDERSTORMS WILL GENERALLY RETAIN A SLY
COMPONENT...VARYING FM SELY TO SWLY WITH GUSTS TO 20-25 KTS AT
TIMES.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 192035
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
335 PM CDT SUN MAY 19 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 331 PM CDT SUN MAY 19 2013
FOCUS FOR STORMS EARLY THIS EVENING IS BACK OVER EASTERN KS/WESTERN
MO...THEN HAVE THIS COMPLEX OF STORMS MOVE EAST INTO
CENTRAL/NORTHEAST MO BY 03Z. STILL SOME UNCERTAINTY ON EXACT
PLACEMENT AND STRENGTH OF STORMS AS THEY MOVE EAST INTO FORECAST
AREA. 12Z MODELS ALL OVER THE PLACE WITH SOME FOCUSING MAIN AREA OF
STORMS ALONG AND SOUTH OF I-70...WHILE OTHERS HAVE A LONG LINE OF
STORMS MOVE ACROSS ENTIRE FORECAST AREA. FOR NOW HAVE AREA OF STORMS
MOVE ACROSS REGION...GRADUALLY WEAKENING/DIMINISHING TOWARDS
DAYBREAK...GOING FROM LIKELY POPS DOWN TO JUST CHANCE POPS BY 11Z.
BEST CHANCES WILL BE OVER WESTERN HALF OF FORECAST AREA. AS FOR
SEVERE WEATHER CHANCES...DECENT CAPES/PWS...LOW LEVEL JET...AND
SHORTWAVE SLIDING THROUGH AREA TONIGHT. SO WESTERN PORTIONS OF
FORECAST AREA STILL IN A SLIGHT RISK OVERNIGHT...WITH MAIN THREAT
BEING DAMAGING WINDS.
OTHERWISE...GUSTY SOUTHEAST TO SOUTH WINDS TO DIMINISH AFTER SUNSET.
MILD WEATHER TO PERSIST WITH LOWS ONLY IN THE MID TO UPPER
60S...WITH LOW 70S IN STL METRO AREA.
BYRD
.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 SUPPERCELLS AS THE DOMINATE STORM MODE
INITIALLY. AT THIS WE ARE EXPECTING A FAVORED WSW-ENE CORIDOOR
FOR STORM DEVELOPMENT AFTER 21Z FROM AROUND JEFFERSON CITY TO
BOWLING GREEN...ALTHO THIS AXIS COULD BE A BIT FUTHER 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM CDT SUN MAY 19 2013
WITH STORMS OUT OF FORECAST AREA...HAVE DRY TAFS FOR NOW WITH
GUSTY SOUTHEAST TO SOUTH WINDS...BEFORE DIMINISHING EARLY THIS
EVENING. NEXT ROUND OF ACTIVITY TO FIRE UP OVER EASTERN KS/WESTERN
MO AND SLIDE EAST OVERNIGHT. STORMS TO REACH KCOU BY 04Z AND KUIN
BY 05Z...COULD SEE MVFR...HIGH END IFR VSBYS/CIGS WITH SOME OF THE
STORMS. AS FOR METRO AREA TAFS...STILL NOT SURE IF STORM COMPLEX WILL
HOLD TOGETHER...SO FOR NOW KEPT VCNTY TS AFTER 09Z. STORMS TO
TAPER OFF FROM WEST TO EAST BY 12Z MONDAY.
SPECIFICS FOR KSTL...WITH STORMS OUT OF FORECAST AREA...HAVE DRY TAFS
FOR NOW WITH GUSTY SOUTHEAST TO SOUTH WINDS...BEFORE DIMINISHING
BY 03Z MONDAY. NEXT ROUND OF ACTIVITY TO FIRE UP OVER EASTERN
KS/WESTERN MO AND SLIDE EAST OVERNIGHT. STILL NOT SURE IF STORM
COMPLEX WILL HOLD TOGETHER AND MAKE IT INTO METRO AREA...SO FOR
NOW KEPT VCNTY TS AFTER 09Z. STORMS TO TAPER OFF BY 12Z
MONDAY...WITH NEXT ROUND FIRING UP BY 21Z MONDAY...SO ADDED VCTS
MENTION DURING THIS PERIOD. SOUTH WINDS TO PERSIST THROUGH THE
REST OF FORECAST PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 191752
AFDLSX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1252 PM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 1251 PM CDT SUN MAY 19 2013
MORNING ACTIVITY THAT MOVED THROUGH CENTRAL/NORTHEAST MO...WEST
CENTRAL IL HAS EXITED. OTHERWISE...WARM FRONT TO CONTINUE SLOWLY
LIFTING NORTH THROUGH FORECAST AREA THIS AFTERNOON. COULD STILL SEE SOME
ISOLATED STORMS EARLY THIS AFTERNOON OVER WEST CENTRAL...SOUTHWESTERN
IL...BUT DRY ELSEWHERE. HIGH TEMPS WILL DEPEND ON CLOUD COVER AND
WARM FRONT...FOR NOW HAVE HIGHS IN THE UPPER 80S TO LOW 90S.
BYRD
&&
.SHORT TERM...(THROUGH WEDNESDAY)
ISSUED AT 253 AM CDT SUN MAY 19 2013
ACTIVE WEATHER PATTERN EXPECTED THROUGH WEDNESDAY IN RESPONSE TO
A SERIES OF SHORTWAVES MOVING ACROSS THE REGION AS AN UPPER LOW/TROF
MOVES FROM THE CENTRAL PLAINS TO THE UPPER MISSISSIPPI RIVER VALLEY.
SEVERAL ROUNDS OF SEVERE THUNDERSTORMS APPEAR LIKELY TO OCCUR...WITH
THE POTENTIAL OF LARGE HAIL...DAMAGING WINDS AND TORNADOES.
WARM FRONT IS CURRENTLY LOCATED TO OUR SOUTHWEST AND LINEAR
CONVECTION FROM THE PLAINS CONTINUES TO DECAY AS IT MOVES INTO
WESTERN MISSOURI. PLENTY OF LOW LEVEL STRATUS AND DEBRIS CLOUDS FROM
WESTERN CONVECTION COVER THE CWA EARLY THIS MORNING.
POTENTIAL FOR A WARM DAY WITH 850MB TEMPERATURES RISING ABOVE
+20C...BUT RESIDUAL CLOUD COVER AND LIFTING WARM FRONT HAS ME
CAUTIOUS ABOUT GOING TOO WARM. HAVE GENERALLY FORECAST HIGHS IN THE
MIDDLE TO UPPER 80S...WHICH IS IN LINE WITH LATEST MOS GUIDANCE.
SHORT TERM MODEL GUIDANCE CONTINUES TO SHOW ISOLATED TO SCATTERED
CONVECTION DEVELOPING ALONG AND NORTH OF THE ADVANCING WARM
FRONT...AND LIKELY SOME RESIDUAL BOUNDARY PUSHING EAST FROM THE
DECAYING CONVECTION. 0-6KM BULK SHEAR AND CAPE OF 2000-3000 K/JG
WOULD SUPPORT MULTICELL DEVELOPMENT AND THE POTENTIAL OF SOME
MARGINAL SEVERE HAIL REPORTS IF INITIATION OCCURS. THINK THIS WILL
MAINLY BE ALONG AND EAST OF THE MISSISSIPPI RIVER.
ATTENTION WILL ONCE AGAIN TURN TO OUR WEST LATE THIS EVENING AS
SEVERE CONVECTION IS EXPECTED TO DEVELOP ACROSS EASTERN KANSAS AND
WESTERN MISSOURI...EVENTUALLY DEVELOPING INTO A LINE AND MOVING EAST
TOWARD THE WESTERN CWA BY LATE EVENING. MAIN THREAT WITH THIS
CONVECTION WOULD BE DAMAGING WIND GUSTS. LINE OF CONVECTION WILL
WEAKEN AS IT MOVES FURTHER EAST TOWARD THE MISSISSIPPI RIVER BY
EARLY MORNING WITH LOSS OF INSTABILITY.
ATMOSPHERE SHOULD EASILY RESET FOR MONDAY...WITH THE POTENTIAL FOR A
MAJOR SEVERE WEATHER OUTBREAK TO OCCUR ACROSS AT LEAST THE WESTERN
HALF OF THE CWA DURING THE AFTERNOON AND EVENING HOURS.
INSTABILY/SHEAR COMBINATION IS SUPPORTIVE OF SUPERCELLS WITH LARGE
HAIL...DAMAGING WIND AND TORNADOES.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE TRENDS FOR TUESDAY AND
WEDNESDAY...BUT COULD SEE TWO MORE ACTIVE DAYS GIVEN POSITION OF THE
LONGWAVE TROF TO OUR NORTHWEST AND APPROACHING COLD FRONT. ONCE
AGAIN...SHEAR/INSTABILITY COMBINATION SUPPORTS SUPERCELLS.
COLD FRONT SHOULD FINALLY MOVE THROUGH THE CWA BY WEDNESDAY
NIGHT...ENDING THE SEVERE WEATHER THREAT.
CVKING
.LONG TERM...(THURSDAY THROUGH SATURDAY)
ISSUED AT 253 AM CDT SUN MAY 19 2013
A REINFORCING COLD FRONT WILL PROVIDE ENOUGH LIFT FOR AT LEAST A
CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. HIGH PRESSURE
RIDGE IN ITS WAKE SHOULD BRING AT LEAST A COUPLE DRY DAYS TO THE
CWA FRIDAY AND SATURDAY BEFORE RETURN FLOW BRINGS INCREASED
CHANCES OF THUNDERSTORMS BACK INTO THE FORECAST FOR THE LATTER
HALF OF THE MEMORIAL DAY WEEKEND. TEMPERATURES WILL REMAIN
SEASONAL WITH HIGHS IN THE 70S AND LOWS IN THE 50S.
CVKING
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM CDT SUN MAY 19 2013
WITH STORMS OUT OF FORECAST AREA...HAVE DRY TAFS FOR NOW WITH
GUSTY SOUTHEAST TO SOUTH WINDS...BEFORE DIMINISHING EARLY THIS
EVENING. NEXT ROUND OF ACTIVITY TO FIRE UP OVER EASTERN KS/WESTERN
MO AND SLIDE EAST OVERNIGHT. STORMS TO REACH KCOU BY 04Z AND KUIN
BY 05Z...COULD SEE MVFR...HIGH END IFR VSBYS/CIGS WITH SOME OF THE
STORMS. AS FOR METRO AREA TAFS...STILL NOT SURE IF STORM COMPLEX WILL
HOLD TOGETHER...SO FOR NOW KEPT VCNTY TS AFTER 09Z. STORMS TO
TAPER OFF FROM WEST TO EAST BY 12Z MONDAY.
SPECIFICS FOR KSTL...WITH STORMS OUT OF FORECAST AREA...HAVE DRY TAFS
FOR NOW WITH GUSTY SOUTHEAST TO SOUTH WINDS...BEFORE DIMINISHING
BY 03Z MONDAY. NEXT ROUND OF ACTIVITY TO FIRE UP OVER EASTERN
KS/WESTERN MO AND SLIDE EAST OVERNIGHT. STILL NOT SURE IF STORM
COMPLEX WILL HOLD TOGETHER AND MAKE IT INTO METRO AREA...SO FOR
NOW KEPT VCNTY TS AFTER 09Z. STORMS TO TAPER OFF BY 12Z
MONDAY...WITH NEXT ROUND FIRING UP BY 21Z MONDAY...SO ADDED VCTS
MENTION DURING THIS PERIOD. SOUTH WINDS TO PERSIST THROUGH THE
REST OF FORECAST PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 190755
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
255 AM CDT SUN MAY 19 2013
.SHORT TERM...(THROUGH WEDNESDAY)
ISSUED AT 253 AM CDT SUN MAY 19 2013
ACTIVE WEATHER PATTERN EXPECTED THROUGH WEDNESDAY IN RESPONSE TO
A SERIES OF SHORTWAVES MOVING ACROSS THE REGION AS AN UPPER LOW/TROF
MOVES FROM THE CENTRAL PLAINS TO THE UPPER MISSISSIPPI RIVER VALLEY.
SEVERAL ROUNDS OF SEVERE THUNDERSTORMS APPEAR LIKELY TO OCCUR...WITH
THE POTENTIAL OF LARGE HAIL...DAMAGING WINDS AND TORNADOES.
WARM FRONT IS CURRENTLY LOCATED TO OUR SOUTHWEST AND LINEAR
CONVECTION FROM THE PLAINS CONTINUES TO DECAY AS IT MOVES INTO
WESTERN MISSOURI. PLENTY OF LOW LEVEL STRATUS AND DEBRIS CLOUDS FROM
WESTERN CONVECTION COVER THE CWA EARLY THIS MORNING.
POTENTIAL FOR A WARM DAY WITH 850MB TEMPERATURES RISING ABOVE
+20C...BUT RESIDUAL CLOUD COVER AND LIFTING WARM FRONT HAS ME
CAUTIOUS ABOUT GOING TOO WARM. HAVE GENERALLY FORECAST HIGHS IN THE
MIDDLE TO UPPER 80S...WHICH IS IN LINE WITH LATEST MOS GUIDANCE.
SHORT TERM MODEL GUIDANCE CONTINUES TO SHOW ISOLATED TO SCATTERED
CONVECTION DEVELOPING ALONG AND NORTH OF THE ADVANCING WARM
FRONT...AND LIKELY SOME RESIDUAL BOUNDARY PUSHING EAST FROM THE
DECAYING CONVECTION. 0-6KM BULK SHEAR AND CAPE OF 2000-3000 K/JG
WOULD SUPPORT MULTICELL DEVELOPMENT AND THE POTENTIAL OF SOME
MARGINAL SEVERE HAIL REPORTS IF INITIATION OCCURS. THINK THIS WILL
MAINLY BE ALONG AND EAST OF THE MISSISSIPPI RIVER.
ATTENTION WILL ONCE AGAIN TURN TO OUR WEST LATE THIS EVENING AS
SEVERE CONVECTION IS EXPECTED TO DEVELOP ACROSS EASTERN KANSAS AND
WESTERN MISSOURI...EVENTUALLY DEVELOPING INTO A LINE AND MOVING EAST
TOWARD THE WESTERN CWA BY LATE EVENING. MAIN THREAT WITH THIS
CONVECTION WOULD BE DAMAGING WIND GUSTS. LINE OF CONVECTION WILL
WEAKEN AS IT MOVES FURTHER EAST TOWARD THE MISSISSIPPI RIVER BY
EARLY MORNING WITH LOSS OF INSTABILITY.
ATMOSPHERE SHOULD EASILY RESET FOR MONDAY...WITH THE POTENTIAL FOR A
MAJOR SEVERE WEATHER OUTBREAK TO OCCUR ACROSS AT LEAST THE WESTERN
HALF OF THE CWA DURING THE AFTERNOON AND EVENING HOURS.
INSTABILY/SHEAR COMBINATION IS SUPPORTIVE OF SUPERCELLS WITH LARGE
HAIL...DAMAGING WIND AND TORNADOES.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE TRENDS FOR TUESDAY AND
WEDNESDAY...BUT COULD SEE TWO MORE ACTIVE DAYS GIVEN POSITION OF THE
LONGWAVE TROF TO OUR NORTHWEST AND APPROACHING COLD FRONT. ONCE
AGAIN...SHEAR/INSTABILITY COMBINATION SUPPORTS SUPERCELLS.
COLD FRONT SHOULD FINALLY MOVE THROUGH THE CWA BY WEDNESDAY
NIGHT...ENDING THE SEVERE WEATHER THREAT.
CVKING
.LONG TERM...(THURSDAY THROUGH SATURDAY)
ISSUED AT 253 AM CDT SUN MAY 19 2013
A REINFORCING COLD FRONT WILL PROVIDE ENOUGH LIFT FOR AT LEAST A
CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. HIGH PRESSURE
RIDGE IN ITS WAKE SHOULD BRING AT LEAST A COUPLE DRY DAYS TO THE
CWA FRIDAY AND SATURDAY BEFORE RETURN FLOW BRINGS INCREASED
CHANCES OF THUNDERSTORMS BACK INTO THE FORECAST FOR THE LATTER
HALF OF THE MEMORIAL DAY WEEKEND. TEMPERATURES WILL REMAIN
SEASONAL WITH HIGHS IN THE 70S AND LOWS IN THE 50S.
CVKING
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1147 PM CDT SAT MAY 18 2013
AN AREA OF STRATUS HAD REACHED KCOU AND WAS MOVING NEWD AT TAF
ISSUANCE. THIS CLOUD DECK MAY PRODUCE BRIEF PDS OF MVFR CIGS AT
METRO AREA TAF SITES. SCT SHOWERS MAY AFFECT THE TERMINALS TOWARDS
DAYBREAK HOWEVER THE BEST PCPN CHCS WILL BE TOWARDS OR BEYOND THE
END OF THE 24HR TAF PD. SELY WINDS WILL TURN SLY AND GUST TO
AROUND 20 KTS DURING THE AFTN.
SPECIFICS FOR KSTL...AN AREA OF STRATUS WAS MOVING NEWD TOWARDS
THE TERMINAL AND MAY PRODUCE A BRIEF PD OF MVFR CIGS BEFORE 09Z
HOWEVER THE OBS ACROSS THE PORTION OF THE STRATUS HEADED TOWARDS
KSTL WAS GENERALLY VFR AT TAF ISSUANCE. SCT SHOWERS MAY AFFECT
THE TERMINAL TOWARDS DAYBREAK HOWEVER THE BEST PCPN CHCS WILL BE
TOWARDS THE END OF THE 30HR TAF PD. SELY WINDS WILL TURN SLY AND
GUST TO AROUND 20 KTS DURING THE AFTN.
KANOFSKY
&&
.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS 89 74 87 67 / 30 40 50 80
QUINCY 86 67 84 66 / 30 70 50 70
COLUMBIA 87 67 83 65 / 10 60 60 80
JEFFERSON CITY 87 67 85 65 / 10 60 60 80
SALEM 86 70 87 70 / 30 30 30 60
FARMINGTON 86 69 85 68 / 20 30 30 80
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 190504
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1204 AM CDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 847 PM CDT SAT MAY 18 2013
MAIN CONCERN CONTINUES TO BE POTENTIAL FOR TSRA ALONG-NE OF THE
WRMFNT AS IT PUSHES NEWD OVERNIGHT. WRMFNT CURRENTLY EXTENDS FROM
SERN KS INTO FAR SWRN MO AND N-CNTRL AR. EXAMINATION OF KSGF RAOB
FROM 00Z INDICATES A DECENT ENOUGH CAP CENTERED AROUND BULGE OF
WARM AIR AT H800 WITH A VERY SIZABLE REGION OF CAPE ABOVE...AROUND
4500 J/KG. BUT TO GET ANYTHING GOING...LIFT WILL HAVE TO COME UP
HIGH WITH SPECIAL ATTENTION AT THE H600-700 LAYER. MOISTURE
CONVERGENCE AT THE H600-700 LAYER WILL NOT ARRIVE UNTIL LATE THIS
EVENING FOR CNTRL-SERN MO AND EVEN THEN WILL BE WEAK. SOME
ADDITIONAL LIFT WILL BE PROVIDED BY A VORT MAX THAT WILL SLIDE
THRU CNTRL AND UP INTO NERN MO AND W-CNTRL IL DURING LATE EVENING
AND EARLY OVERNIGHT...AND SO HAVE ESSENTIALLY TIED RAIN CHCS TO
THESE FEATURES...STARTING WITH SLIGHT CHC BUT EDGING HIGHER INTO
LO CHC CATEGORY WITH TIME EITHER FROM THE ENHANCED LIFT FROM THE
VORT MAX OR STRONGER MOISTURE CONVERGENCE. THIS SHOULD ALL EXIT BY
15Z/SUNDAY. WITH PLENTY OF CAPE TO WORK WITH FOR ANY CELLS THAT DO
POP AND MARGINAL SHEAR...CAN SEE HAIL POTENTIAL...ALTHOUGH LIMITED
A BIT BY THE HIGH FRZG LEVELS.
ATTENTION THEN TURNS TOWARDS WHAT SHOULD BE THE FIRST OF A FEW
POTENTIALLY SEVERE EVENTS. SVR TSRA OVER THE PLAINS NOW SHOULD
WEAKEN AND GET DEFLECTED MAINLY TO THE NW...ALTHOUGH MAY GET SOME
ON SUNDAY MORNING THRU NERN-CNTRL MO AND W-CNTRL IL. OUTSIDE OF
THAT...OUR REGION LOOKS PRETTY DEVOID OF ANY LIFT AND SHOULD HAVE
ENOUGH OF A CAP TO PRECLUDE TSRA DEVELOPMENT...ESPECIALLY WITH
DWPTS EXPECTED TO DRY OUT A BIT SUNDAY AFTERNOON AFTER PEAKING IN
THE LO 70S IN SPOTS EARLIER IN THE DAY. AGGRESSIVE STANCE ON MAX
TEMPS LOOKS GOOD.
TES
&&
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ
COULD CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE
LATE OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR
DEVELOP SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY
THROUGH THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN
TONIGHT`S FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A
FOCUSED AREA OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE
OVERNIGHT HOURS AND TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1147 PM CDT SAT MAY 18 2013
AN AREA OF STRATUS HAD REACHED KCOU AND WAS MOVING NEWD AT TAF
ISSUANCE. THIS CLOUD DECK MAY PRODUCE BRIEF PDS OF MVFR CIGS AT
METRO AREA TAF SITES. SCT SHOWERS MAY AFFECT THE TERMINALS TOWARDS
DAYBREAK HOWEVER THE BEST PCPN CHCS WILL BE TOWARDS OR BEYOND THE
END OF THE 24HR TAF PD. SELY WINDS WILL TURN SLY AND GUST TO
AROUND 20 KTS DURING THE AFTN.
SPECIFICS FOR KSTL...AN AREA OF STRATUS WAS MOVING NEWD TOWARDS
THE TERMINAL AND MAY PRODUCE A BRIEF PD OF MVFR CIGS BEFORE 09Z
HOWEVER THE OBS ACROSS THE PORTION OF THE STRATUS HEADED TOWARDS
KSTL WAS GENERALLY VFR AT TAF ISSUANCE. SCT SHOWERS MAY AFFECT
THE TERMINAL TOWARDS DAYBREAK HOWEVER THE BEST PCPN CHCS WILL BE
TOWARDS THE END OF THE 30HR TAF PD. SELY WINDS WILL TURN SLY AND
GUST TO AROUND 20 KTS DURING THE AFTN.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 190147
AFDLSX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
847 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 847 PM CDT SAT MAY 18 2013
MAIN CONCERN CONTINUES TO BE POTENTIAL FOR TSRA ALONG-NE OF THE
WRMFNT AS IT PUSHES NEWD OVERNIGHT. WRMFNT CURRENTLY EXTENDS FROM
SERN KS INTO FAR SWRN MO AND N-CNTRL AR. EXAMINATION OF KSGF RAOB
FROM 00Z INDICATES A DECENT ENOUGH CAP CENTERED AROUND BULGE OF
WARM AIR AT H800 WITH A VERY SIZABLE REGION OF CAPE ABOVE...AROUND
4500 J/KG. BUT TO GET ANYTHING GOING...LIFT WILL HAVE TO COME UP
HIGH WITH SPECIAL ATTENTION AT THE H600-700 LAYER. MOISTURE
CONVERGENCE AT THE H600-700 LAYER WILL NOT ARRIVE UNTIL LATE THIS
EVENING FOR CNTRL-SERN MO AND EVEN THEN WILL BE WEAK. SOME
ADDITIONAL LIFT WILL BE PROVIDED BY A VORT MAX THAT WILL SLIDE
THRU CNTRL AND UP INTO NERN MO AND W-CNTRL IL DURING LATE EVENING
AND EARLY OVERNIGHT...AND SO HAVE ESSENTIALLY TIED RAIN CHCS TO
THESE FEATURES...STARTING WITH SLIGHT CHC BUT EDGING HIGHER INTO
LO CHC CATEGORY WITH TIME EITHER FROM THE ENHANCED LIFT FROM THE
VORT MAX OR STRONGER MOISTURE CONVERGENCE. THIS SHOULD ALL EXIT BY
15Z/SUNDAY. WITH PLENTY OF CAPE TO WORK WITH FOR ANY CELLS THAT DO
POP AND MARGINAL SHEAR...CAN SEE HAIL POTENTIAL...ALTHOUGH LIMITED
A BIT BY THE HIGH FRZG LEVELS.
ATTENTION THEN TURNS TOWARDS WHAT SHOULD BE THE FIRST OF A FEW
POTENTIALLY SEVERE EVENTS. SVR TSRA OVER THE PLAINS NOW SHOULD
WEAKEN AND GET DEFLECTED MAINLY TO THE NW...ALTHOUGH MAY GET SOME
ON SUNDAY MORNING THRU NERN-CNTRL MO AND W-CNTRL IL. OUTSIDE OF
THAT...OUR REGION LOOKS PRETTY DEVOID OF ANY LIFT AND SHOULD HAVE
ENOUGH OF A CAP TO PRECLUDE TSRA DEVELOPMENT...ESPECIALLY WITH
DWPTS EXPECTED TO DRY OUT A BIT SUNDAY AFTERNOON AFTER PEAKING IN
THE LO 70S IN SPOTS EARLIER IN THE DAY. AGGRESSIVE STANCE ON MAX
TEMPS LOOKS GOOD.
TES
&&
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ
COULD CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE
LATE OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR
DEVELOP SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY
THROUGH THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN
TONIGHT`S FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A
FOCUSED AREA OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE
OVERNIGHT HOURS AND TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 639 PM CDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE NEXT FEW HOURS WITH
INCREASING UNCERTAINTY AFTER 06Z. AN AREA OF SHOWERS AND
THUNDERSTORMS IS EXPECTED TO DEVELOP OVER PARTS OF MO/IL OVERNIGHT
DUE TO A WARM FRONT LIFTING THROUGH THE AREA IN THE PRESENCE OF AN
UNSTABLE AIR MASS. VCSH LOOKS REASONABLE ATTM DUE TO UNCERTAINTY
REGARDING COVERAGE AND TIMING. SOUTHEASTERLY WINDS WILL BECOME
SOUTHERLY TOMORROW AND GUST TO AROUND 20-25 KTS ON THE WARM SIDE
OF THE FRONT. SCT SHOWERS AND THUNDERSTORMS ARE POSSIBLE NEAR PEAK
HEATING TOMORROW AFTN /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES
LEFT OVER FROM EARLIER CONVECTION/.
SPECIFICS FOR KSTL...VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE
NEXT FEW HOURS FOLLOWED BY INCREASING UNCERTAINTY AFTER 06Z. AN
AREA OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO DEVELOP OVER
PARTS OF MISSOURI OVERNIGHT DUE TO A WARM FRONT LIFTING THROUGH
THE AREA IN THE PRESENCE OF AN UNSTABLE AIR MASS. THE COVERAGE AND
SOUTHERN EXTENT OF THE OVERNIGHT CONVECTION ARE UNCERTAIN AT THIS
TIME HOWEVER THE VCSH TIMING IN THE PREVIOUS TAF LOOKS REASONABLE.
SOUTHEASTERLY WINDS WILL BECOME SOUTHERLY AND GUST TO AROUND 20
KTS TOMORROW ON THE WARM SIDE OF THE FRONT. SCT SHOWERS AND
THUNDERSTORMS ARE POSSIBLE NEAR PEAK HEATING TOMORROW
AFTERNOON /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES LEFT OVER FROM
EARLIER CONVECTION/ BUT THE BEST CHC FOR PCPN WILL BE AFTER THE
END OF THE VALID TAF PD.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 182350
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
650 PM CDT SAT MAY 18 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
(TONIGHT)
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ COULD
CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE LATE
OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR DEVELOP
SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY THROUGH
THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN TONIGHT`S
FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A FOCUSED AREA
OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE OVERNIGHT HOURS AND
TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 639 PM CDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE NEXT FEW HOURS WITH
INCREASING UNCERTAINTY AFTER 06Z. AN AREA OF SHOWERS AND
THUNDERSTORMS IS EXPECTED TO DEVELOP OVER PARTS OF MO/IL OVERNIGHT
DUE TO A WARM FRONT LIFTING THROUGH THE AREA IN THE PRESENCE OF AN
UNSTABLE AIR MASS. VCSH LOOKS REASONABLE ATTM DUE TO UNCERTAINTY
REGARDING COVERAGE AND TIMING. SOUTHEASTERLY WINDS WILL BECOME
SOUTHERLY TOMORROW AND GUST TO AROUND 20-25 KTS ON THE WARM SIDE
OF THE FRONT. SCT SHOWERS AND THUNDERSTORMS ARE POSSIBLE NEAR PEAK
HEATING TOMORROW AFTN /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES
LEFT OVER FROM EARLIER CONVECTION/.
SPECIFICS FOR KSTL...VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE
NEXT FEW HOURS FOLLOWED BY INCREASING UNCERTAINTY AFTER 06Z. AN
AREA OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO DEVELOP OVER
PARTS OF MISSOURI OVERNIGHT DUE TO A WARM FRONT LIFTING THROUGH
THE AREA IN THE PRESENCE OF AN UNSTABLE AIR MASS. THE COVERAGE AND
SOUTHERN EXTENT OF THE OVERNIGHT CONVECTION ARE UNCERTAIN AT THIS
TIME HOWEVER THE VCSH TIMING IN THE PREVIOUS TAF LOOKS REASONABLE.
SOUTHEASTERLY WINDS WILL BECOME SOUTHERLY AND GUST TO AROUND 20
KTS TOMORROW ON THE WARM SIDE OF THE FRONT. SCT SHOWERS AND
THUNDERSTORMS ARE POSSIBLE NEAR PEAK HEATING TOMORROW
AFTERNOON /ESPECIALLY ALONG ANY OUTFLOW BOUNDARIES LEFT OVER FROM
EARLIER CONVECTION/ BUT THE BEST CHC FOR PCPN WILL BE AFTER THE
END OF THE VALID TAF PD.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 182014
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
314 PM CDT SAT MAY 18 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
(TONIGHT)
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ COULD
CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE LATE
OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR DEVELOP
SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY THROUGH
THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN TONIGHT`S
FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A FOCUSED AREA
OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE OVERNIGHT HOURS AND
TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM CDT SAT MAY 18 2013
FOG HAS DISSIPATED ACROSS THE REGION...THOUGH CIGS HAVE BEEN A BIT
SLOW TO RECOVER...PARTICULARLY ACROSS NORTHEAST MO AND OVER THE
OZARKS. LATEST VISIBLE SATELLITE IMAGERY SHOWS AN EXTENSIVE
CUMULUS FIELD DEVELOPING OVER THE MISSISSIPPI VALLEY...THOUGH
EXPECT THE GRADUAL IMPROVEMENT IN CIGS TO CONTINUE THIS
AFTERNOON...WITH JUST SOME SCT VFR CLOUDS EXPECTED.
A NW-SE ORIENTED WARM FRONT WILL SHIFT NORTHWARD ACROSS THE REGION
OVERNIGHT TONIGHT...AND MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF SOME SHRA/TSRA ALONG AND AHEAD OF THE ADVANCING
WARM FRONT. FOR NOW...HAVE INCLUDED MENTION OF VCSH FOR AREA TAF
SITES DURING THE EARLY MORNING HOURS...AND WILL DEFER TO LATER TAF
ISSUANCES TO FURTHER PIN DOWN TIMING AND/OR MENTION OF TSRA.
OTHERWISE...WINDS WILL REMAIN SOUTHEASTERLY TODAY AND VEER TO
THE SOUTH ON SUNDAY...INCREASING TO ABOUT 10-12KT WITH SOME GUSTS
AS RETURN FLOW SETS IN.
SPECIFICS FOR KSTL...
CIGS ARE EXPECTED TO CONTINUE TO IMPROVE TO SCT VFR THIS
AFTERNOON...WITH LIGHT SOUTHEAST WINDS. OVERNIGHT TONIGHT A WARM
FRONT WILL DRIFT NORTH ACROSS THE AREA...AND MODELS CONTINUE TO
INDICATE SOME SHRA/TSRA DEVELOPMENT ACCOMPANYING THE FRONT. HAVE
CURRENTLY INCLUDED VCSH MENTION FOR KSTL FROM 10-13Z...THOUGH
TIMING WILL LIKELY NEED REFINED IN LATER TAF ISSUANCES...ALONG
WITH POTENTIAL THUNDER MENTION WHEN COVERAGE/INTENSITY BECOMES
MORE CLEAR. WINDS WILL VEER TO THE SOUTH TOMORROW BEHIND THE
ADVANCING WARM FRONT...INCREASING TO 10-12KT AND GUSTING TO
20-22KT BY THE AFTERNOON.
JP
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
000
FXUS63 KLSX 181805
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
105 PM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM CDT SAT MAY 18 2013
BOTH FOG AND STRATUS HAVE DEVELOPED ACROSS SOUTHEAST MISSOURI AND
SOUTHERN ILLINOIS DURING THE OVERNIGHT HOURS...WITH PATCHY FOG
FURTHER NORTH. ADDITIONAL DEVELOPMENT TO THE NW SHOULD CONTINUE
THROUGH DAYBREAK. AT THIS TIME DENSE FOG IS CONFINED TO THE FAR SRN
CWA AND WILL ISSUE AN ADVISORY FOR THIS REGION UP TO SULLIVAN
THROUGH 14Z. MOST AREAS WILL SEE A DRY DAY WITH WARMER TEMPERATURES
AS THE PLAINS UPPER RIDGE SHIFTS INTO THE MS VALLEY AND LOW LEVEL
WAA GETS UNDERWAY. THE EXCEPTION MIGHT BE IN SOUTH CENTRAL IL
ALONG THE BACKSIDE OF THE RETREATING AND WEAKENING UPPER LOW WHERE
AN ISOLATED DIURNAL SHOWER IS POSSIBLE.
I AM STILL THINKING THERE IS POTENTIAL FOR SCATTERED ELEVATED
THUNDERSTORMS OVERNIGHT TONIGHT. MID LEVEL LAPSE RATES STEEPEN
QUITE A BIT AND THIS COMBINED WITH LOW LEVEL WAA/MOISTURE TRANSPORT
AND CONVERGENCE/LIFT VIA A SWLY LLJ WILL RESULT IN THE THREAT OF
ELEVATED STORMS TO THE NORTH OF A WNW-ESE ORIENTED WARM FRONT
DRAPPED ACROSS SOUTHERN MO. SOME OF THE CONVECTION ALLOWING MODELS
INCLUDING THE NSSL 4KM WRF SUPPORT THIS SCENARIO SHOWING SCATTERED
CONVECTIVE DEVELOPMENT IN A NW-SE ZONE ACROSS EASTERN MO BETWEEN
06-09Z.
GLASS
.LONG TERM...( SUNDAY THROUGH THURSDAY)
ISSUED AT 325 AM CDT SAT MAY 18 2013
AN ACTIVE PERIOD OF WEATHER IS ON TAP FOR THE AREA FROM SUNDAY
THROUGH WEDNESDAY AS A COMPLEX LONG WAVE TROF SLOWLY MIGRATES
THROUGH THE NATIONS MIDSECTION WHILE A SERIES OF SHORT WAVES
EJECT ENEWD THRU THE BASE AND ACROSS PORTIONS OF THE MID/UPPER MS
VALLEY. MULTIPLE SEVERE WEATHER EPISODES ARE POSSIBLE IN THE
SUNDAY NIGHT THROUGH TUESDAY NIGHT TIME FRAME AND UNTIL THE FRONT
FINALLY PUSHES TO THE EAST OF THE CWA LATE WEDNESDAY.
SUNDAY LOOKS LIKE A WARM DAY WITH STRENGTHENING WAA AND H85 TEMPS
RISING TO ABOVE +19 DEGC. THE AFOREMENTIONED WARM FRONT WILL BE
LIFTING NORTHWARD DURING THE DAY AND THE WARM SECTOR SHOULD BECOME
QUITE UNSTABLE BUT LOOKS CAPPED. IN QUESTION IS THE AREA ACROSS NE
MO AND WEST CENTRAL IL WHERE SOME OF THE MODELS WANT TO DEVELOP
DEEP CONVECTION...APPARENTLY TO THE NORTH OF THE RETREATING WARM
FRONT. DEEP LAYER SHEAR AT THIS TIME FRAME IS MORE SUPPORTIVE OF
MULTICELLS CAPABLE OF LARGE HAIL. THE THUNDERSTORM AND SEVERE
WEATHER THREAT WILL RAMP UP ON SUNDAY NIGHT...SPECIFICALLY ACROSS
CENTRAL MO AND INTO NE MO. A SIGNFICANT SHORT WAVE IS FORECAST TO
ROTATE NEWD FROM KS/OK AND INTO IOWA WITH AN ACCOMPANYING MID
LEVEL WIND MAX. THIS WILL STRENGTHEN THE DEEP LAYER SHEAR. AT THIS
TIME I EXPECT THAT SEVERE STORMS ACROSS EASTERN KS AND WESTERN MO
WILL GROW UPSCALE AND SHIFT EASTWARD INTO CENTRAL MO...WEAKING
LATE ACROSS EASTERN MO. CONVECTIVE TRENDS ARE A BIT UNCERTAIN ON
MONDAY MORNING BUT ANY ONGOING STORMS ARE EXPECTED TO DIMINISH AS
LARGE SCALE SUBSIDENCE DOMINATES IN THE WAKE OF THE LIFTING SHORT
WAVE. BY LATE AFTERNOON/EARLY MONDAY EVENING A SURFACE FRONT IS
EXPECTED TO LIE FROM THE SURFACE LOW IN IOWA ACROSS NW MO INTO SE
KS. THE WARM SECTOR AIR MASS WILL BE AT LEAST MODERATELY UNSTABLE
WITH LITTLE CAP IN A BROAD ZONE WHERE WSW DEEP LAYER SHEAR WILL BE
AOA 40 KTS...SUPPORTIVE OF SUPERCELLS. AT THIS TIME EXPECTING
SCATTERED STORMS TO DEVELOP DURING THE LATE AFTERNOON/EARLY
EVENING WITHIN THIS ZONE WITH AN UPSWING IN COVERAGE DURING THE
EVENING AS THE NEXT SHORTWAVE SPREADS LARGE SCALE ASCENT INTO THE
MID MS VALLEY. ONGOING CONVECTION ON TUESDAY MORNING LEADS TO
UNCERTAINTY IN THE DETAILS FOR TUESDAY/TUESDAY NIGHT...BUT THE
GENERAL SYNOPTIC PATTERN OF ANOTHER EJECTING SHORT WAVE AND
ATTENDANT PROGRESSING COLD FRONT ALONG WITH AT LEAST WEAK-MODERATE
INSTABILITY AND DEEP LAYER SHEAR OF 30-40 KTS SUPPORTS POTENTIAL
FOR A CONTINUED SEVERE WEATHER THREAT AND NUMEROUS THUNDERSTORMS.
GLASS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM CDT SAT MAY 18 2013
FOG HAS DISSIPATED ACROSS THE REGION...THOUGH CIGS HAVE BEEN A BIT
SLOW TO RECOVER...PARTICULARLY ACROSS NORTHEAST MO AND OVER THE
OZARKS. LATEST VISIBLE SATELLITE IMAGERY SHOWS AN EXTENSIVE
CUMULUS FIELD DEVELOPING OVER THE MISSISSIPPI VALLEY...THOUGH
EXPECT THE GRADUAL IMPROVEMENT IN CIGS TO CONTINUE THIS
AFTERNOON...WITH JUST SOME SCT VFR CLOUDS EXPECTED.
A NW-SE ORIENTED WARM FRONT WILL SHIFT NORTHWARD ACROSS THE REGION
OVERNIGHT TONIGHT...AND MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF SOME SHRA/TSRA ALONG AND AHEAD OF THE ADVANCING
WARM FRONT. FOR NOW...HAVE INCLUDED MENTION OF VCSH FOR AREA TAF
SITES DURING THE EARLY MORNING HOURS...AND WILL DEFER TO LATER TAF
ISSUANCES TO FURTHER PIN DOWN TIMING AND/OR MENTION OF TSRA.
OTHERWISE...WINDS WILL REMAIN SOUTHEASTERLY TODAY AND VEER TO
THE SOUTH ON SUNDAY...INCREASING TO ABOUT 10-12KT WITH SOME GUSTS
AS RETURN FLOW SETS IN.
SPECIFICS FOR KSTL...
CIGS ARE EXPECTED TO CONTINUE TO IMPROVE TO SCT VFR THIS
AFTERNOON...WITH LIGHT SOUTHEAST WINDS. OVERNIGHT TONIGHT A WARM
FRONT WILL DRIFT NORTH ACROSS THE AREA...AND MODELS CONTINUE TO
INDICATE SOME SHRA/TSRA DEVELOPMENT ACCOMPANYING THE FRONT. HAVE
CURRENTLY INCLUDED VCSH MENTION FOR KSTL FROM 10-13Z...THOUGH
TIMING WILL LIKELY NEED REFINED IN LATER TAF ISSUANCES...ALONG
WITH POTENTIAL THUNDER MENTION WHEN COVERAGE/INTENSITY BECOMES
MORE CLEAR. WINDS WILL VEER TO THE SOUTH TOMORROW BEHIND THE
ADVANCING WARM FRONT...INCREASING TO 10-12KT AND GUSTING TO
20-22KT BY THE AFTERNOON.
JP
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
| 
