869 
FXUS63 KLSX 122018
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
318 PM CDT TUE MAR 12 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 316 PM CDT TUE MAR 12 2013

(TONIGHT)

SECONDARY COLD FRONT SHOULD EXIT THE CWA EARLY THIS EVENING WITH A 
RIDGE OF HIGH PRESSURE SLOWLY MOVING IN FROM THE NORTHWEST. KEPT SCH 
POPS FOR RAIN/SNOW THIS EVENING GENERALLY ALONG AND NORTHEAST OF 
MISSISSIPPI RIVER ALONG TRACK OF 500-HPA VORT. ANY PRECIPITATION 
THAT DOES OCCUR SHOULD BE VERY LIGHT HOWEVER. OTHER CONCERN FOR 
TONIGHT IS TEMPERATURES. STRONG LOW-LEVEL CAA WILL BE IN FULL FORCE 
BEHIND AFOREMENTIONED BOUNDARY. HOWEVER...LOW STRATUS MOVING 
IN FROM NW WILL LIKELY BE IN PLACE MOST OF THE NIGHT ESPECIALLY FOR 
THE EASTERN HALF OF THE AREA. SKIES MAY AT LEAST SCATTER OUT OVER 
FAR WESTERN SECTIONS SO HAVE ELECTED TO GO NEAR THE COLDER MAV 
GUIDANCE. THIS AREA WILL ALSO HAVE LIGHTER WINDS IN CLOSE PROXIMITY 
TO SFC ANTICYCLONE. ELSEWHERE...WITH MOSTLY CLOUDY OR CLOUDY SKIES 
FORECAST...FAVORED WARMER MET MOS.

GOSSELIN

&&

.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 316 PM CDT TUE MAR 12 2013

(WEDNESDAY THROUGH FRIDAY)

SHOULD SEE LOW CLOUDS MOVE EAST WEDNESDAY MORNING AS THE UPPER LEVEL 
TROF MOVES OVER THE EASTERN SEABOARD.  THE SURFACE RIDGE CURRENTLY 
OVER EASTERN COLORADO WILL EXPAND SOUTHEAST ACROSS THE MISSISSIPPI 
VALLEY THROUGH THE DAY.  HAVE TENDED TOWARD THE LOW END OF GUIDANCE 
FOR TEMPERATURES ON WEDNESDAY AS WE SHOULD BE IN NORTHWEST FLOW FOR 
A GOOD PORTION OF THE DAY...AND CLOUDS WILL LIKELY STICK AROUND 
ALONG AND EAST OF THE MISSISSIPPI FOR AT LAST PART OF THE MORNING.

THURSDAY'S FORECAST IS STILL A LITTLE UNCERTAIN.  WE REMAIN IN 
NORTHWEST FLOW ALOFT...EVEN AS THE SURFACE HIGH DROPS DOWN ACROSS 
THE LOWER MISSISSIPPI VALLEY PROVIDING OUR AREA WITH SOUTHWEST TO 
WEST FLOW IN THE LOW LEVELS.  A WEAK SHORTWAVE WILL SPEED BY US IN 
THE NORTHWESTERLY FLOW PROVIDING MID AND UPPER LEVEL SUPPORT FOR 
PRECIP.  THIS ALONG WITH THE LOW LEVEL WARM ADVECTION FROM THE 
WEST-SOUTHWEST FLOW COULD BE ENOUGH TO PRODUCE SOME RAIN.  THINK THE 
BEST CHANCE FOR RAIN WILL BE OVER ILLINOIS THURSDAY AFTERNOON...BUT 
GUIDANCE IS A BIT WISHY-WASHY SO HAVE ONLY BUMPED UP TO CHANCE POPS 
AT THIS TIME.  TEMPS LOOK QUITE MILD...IN THE MID 50S TO LOW AND MID 
60S AND 850MB TEMPS SHOULD BE WELL ABOVE ZERO...SO PRECIP SHOULD BE 
ALL LIQUID.

MILD WEATHER CONTINUES ON FRIDAY AS SOUTHWEST FLOW PUSHES 850MB 
TEMPS INTO DOUBLE DIGIT TERRITORY.  MOST OF THE AREA SHOULD BE IN 
THE LOW TO MID 60S...BUT PARTS OF CENTRAL MISSOURI COULD BREAK 70 
DEGREES.

(SATURDAY THROUGH TUESDAY)

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT A STRONG COLD FRONT 
WILL PASS THROUGH THE AREA LATE FRIDAY NIGHT/EARLY SATURDAY 
MORNING.  THE FRONT LOOKS TO GO THROUGH MOSTLY DRY DUE TO A LACK OF 
DEEP MOISTURE.  IF ANY PRECIP DOES OCCUR WITH THE FRONT IT SHOULD BE 
PRETTY SPOTTY AND LIGHT.  THE FRONT STALLS OVER NORTHERN ARKANSAS 
SATURDAY NIGHT WITH THE 850MB BAROCLINIC ZONE SITTING OVER SOUTHERN 
MISSOURI.  BOTH THE GFS AND ECMWF DEVELOP PRECIP IN RESPONSE TO 
ISENTROPIC LIFT OVER THE BAROCLINIC ZONE SATURDAY NIGHT.  CAN'T RULE 
OUT THUNDER AS THE GFS HAS SOME WEAK MUCAPE ACROSS THE SOUTHERN 1/3 
OF MISSOURI LATE SATURDAY NIGHT...BUT VALUES ARE GENERALLY LESS THAN 
100 J/KG SO HAVE LEFT THUNDER OUT FOR NOW.  STRONG LOW LEVEL 
BAROCLINICITY REMAINS IN PLACE SUNDAY THROUGH MONDAY AS A COUPLE OF 
SHORTWAVES SHOOT BY...EACH PRODUCING ANOTHER CHANCE FOR A ROUND OF 
PRECIP.  ALTHOUGH IT LOOKS LIKE WE WILL REMAIN ON THE COOL SIDE OF 
THE FRONT...INDICATIONS ARE THAT LOW LEVEL TEMPERATURES WILL REMAIN 
WARM ENOUGH TO KEEP ALL THE PRECIP LIQUID.  THAT BEING SAID...THE 
AIR UP ACROSS SOUTHERN CANADA AND THE DAKOTAS AT THAT TIME IS 
FORECAST TO BE VERY COLD.  IF THE HIGH ASSOCIATED WITH THAT AIR 
SHIFTS FURTHER SOUTHWARD THAN EXPECTED THERE COULD BE SOME WINTRY 
PRECIP ACROSS NORTHERN SECTIONS OF THE AREA BEFORE ALL IS SAID AND 
DONE.

CARNEY

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1231 PM CDT TUE MAR 12 2013

PRIMARY CONCERN FOR THE VALID TAF PERIOD WILL BE CEILINGS.
SECONDARY COLD FRONT IS FORECAST TO MOVE THROUGH THIS
AFTERNOON/EARLY EVENING WITH WEST WINDS SHIFTING TO THE NORTHWEST
AND BECOMING GUSTY. BEHIND THIS BOUNDARY...COMBINATION OF LOW
STRATUS ADVECTING SOUTHEAST AND DIURNAL CUMULUS DEVELOPING
OVERHEAD SHOULD YIELD INCREASING AND LOWERING OF CLOUDS THIS
AFTERNOON. MVFR CEILINGS BETWEEN 2000 AND 3000 FEET LOOK TO AFFECT
THE VALID TAF SITES THIS EVENING UNTIL EARLY TOMORROW MORNING.
WENT A BIT PESSIMISTIC AND KEPT MVFR CLOUD DECK A FEW HOURS PAST
WHAT GUIDANCE SUGGESTED...MAINLY DUE TO FACT THAT SIMILAR
SITUATIONS THIS COLD SEASON HAVE YIELDED SIMILAR RESULTS. BY MID
MORNING...SKIES AT ALL VALID TAF SITES SHOULD SCATTER AND THEN
CLEAR OUT WITH WINDS REMAINING OUT OF THE NORTHWEST AROUND 10-15
KTS.

SPECIFICS FOR KSTL...

PRIMARY CONCERN FOR THE VALID TAF PERIOD WILL BE CEILINGS.
SECONDARY COLD FRONT IS FORECAST TO MOVE THROUGH THIS
AFTERNOON/EARLY EVENING WITH WEST WINDS SHIFTING TO THE NORTHWEST
AND BECOMING GUSTY. BEHIND THIS BOUNDARY...COMBINATION OF LOW
STRATUS ADVECTING SOUTHEAST AND DIURNAL CUMULUS DEVELOPING OVERHEAD SHOULD
YIELD INCREASING AND LOWERING OF CLOUDS THIS AFTERNOON. MVFR
CEILINGS BETWEEN 2000 AND 3000 FEET LOOK TO AFFECT LAMBERT FIELD BEGINNING THIS
EVENING AND LASTING UNTIL EARLY TOMORROW MORNING. WENT A BIT
PESSIMISTIC AND KEPT MVFR CLOUD DECK UNTIL 1500 UTC OR A FEW HOURS
PAST WHAT GUIDANCE SUGGESTED...MAINLY DUE TO FACT THAT SIMILAR
SITUATIONS THIS COLD SEASON HAVE YIELDED SIMILAR RESULTS. BY MID-LATE
MORNING...SKIES SHOULD SCATTER AND THEN CLEAR OUT WITH WINDS
REMAINING OUT OF THE NORTHWEST AROUND 10-15 KTS.

OTHER CHANGE TO PREVIOUS FORECAST WAS TO ADD GUSTS THROUGH MOST OF
TONIGHT. UPSTREAM OBSERVATIONS WELL BEHIND SECONDARY COLD FRONT
INTO NEBARASKA AND THE DAKOTAS SUGGEST THIS POSSIBILITY AS DOES
NWP SOUNDINGS WITH DEEP MIXING CONTINUING THROUGHOUT THE NIGHT.

GOSSELIN

&&

.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS     29  44  31  59 /  20   0  10  20 
QUINCY          25  39  28  54 /  20   0  10  30 
COLUMBIA        22  44  30  62 /   5   0   5  10 
JEFFERSON CITY  23  43  29  63 /   5   0   5  10 
SALEM           31  39  27  50 /  20   0  10  30 
FARMINGTON      25  44  27  59 /   5   0   5  20 

&&

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

$$

WFO LSX

982 
FXUS63 KLSX 122028 CCA
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
318 PM CDT TUE MAR 12 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 316 PM CDT TUE MAR 12 2013

(TONIGHT)

SECONDARY COLD FRONT SHOULD EXIT THE CWA EARLY THIS EVENING WITH A 
RIDGE OF HIGH PRESSURE SLOWLY MOVING IN FROM THE NORTHWEST. HAVE CHC-SCH 
POPS FOR RAIN/SNOW THIS EVENING GENERALLY ALONG AND NORTHEAST OF 
MISSISSIPPI RIVER ALONG TRACK OF 500-HPA VORT. ANY PRECIPITATION 
THAT DOES OCCUR SHOULD BE LIGHT HOWEVER. OTHER CONCERN FOR 
TONIGHT IS TEMPERATURES. STRONG LOW-LEVEL CAA WILL BE IN FULL FORCE 
BEHIND AFOREMENTIONED BOUNDARY. HOWEVER...LOW STRATUS MOVING 
IN FROM NW WILL LIKELY BE IN PLACE MOST OF THE NIGHT ESPECIALLY FOR 
THE EASTERN HALF OF THE AREA. SKIES MAY AT LEAST SCATTER OUT OVER 
FAR WESTERN SECTIONS SO HAVE ELECTED TO GO NEAR THE COLDER MAV 
GUIDANCE. THIS AREA WILL ALSO HAVE LIGHTER WINDS IN CLOSE PROXIMITY 
TO SFC ANTICYCLONE. ELSEWHERE...WITH MOSTLY CLOUDY OR CLOUDY SKIES 
FORECAST...FAVORED WARMER MET MOS.

GOSSELIN

&&

.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 316 PM CDT TUE MAR 12 2013

(WEDNESDAY THROUGH FRIDAY)

SHOULD SEE LOW CLOUDS MOVE EAST WEDNESDAY MORNING AS THE UPPER LEVEL 
TROF MOVES OVER THE EASTERN SEABOARD.  THE SURFACE RIDGE CURRENTLY 
OVER EASTERN COLORADO WILL EXPAND SOUTHEAST ACROSS THE MISSISSIPPI 
VALLEY THROUGH THE DAY.  HAVE TENDED TOWARD THE LOW END OF GUIDANCE 
FOR TEMPERATURES ON WEDNESDAY AS WE SHOULD BE IN NORTHWEST FLOW FOR 
A GOOD PORTION OF THE DAY...AND CLOUDS WILL LIKELY STICK AROUND 
ALONG AND EAST OF THE MISSISSIPPI FOR AT LAST PART OF THE MORNING.

THURSDAY'S FORECAST IS STILL A LITTLE UNCERTAIN.  WE REMAIN IN 
NORTHWEST FLOW ALOFT...EVEN AS THE SURFACE HIGH DROPS DOWN ACROSS 
THE LOWER MISSISSIPPI VALLEY PROVIDING OUR AREA WITH SOUTHWEST TO 
WEST FLOW IN THE LOW LEVELS.  A WEAK SHORTWAVE WILL SPEED BY US IN 
THE NORTHWESTERLY FLOW PROVIDING MID AND UPPER LEVEL SUPPORT FOR 
PRECIP.  THIS ALONG WITH THE LOW LEVEL WARM ADVECTION FROM THE 
WEST-SOUTHWEST FLOW COULD BE ENOUGH TO PRODUCE SOME RAIN.  THINK THE 
BEST CHANCE FOR RAIN WILL BE OVER ILLINOIS THURSDAY AFTERNOON...BUT 
GUIDANCE IS A BIT WISHY-WASHY SO HAVE ONLY BUMPED UP TO CHANCE POPS 
AT THIS TIME.  TEMPS LOOK QUITE MILD...IN THE MID 50S TO LOW AND MID 
60S AND 850MB TEMPS SHOULD BE WELL ABOVE ZERO...SO PRECIP SHOULD BE 
ALL LIQUID.

MILD WEATHER CONTINUES ON FRIDAY AS SOUTHWEST FLOW PUSHES 850MB 
TEMPS INTO DOUBLE DIGIT TERRITORY.  MOST OF THE AREA SHOULD BE IN 
THE LOW TO MID 60S...BUT PARTS OF CENTRAL MISSOURI COULD BREAK 70 
DEGREES.

(SATURDAY THROUGH TUESDAY)

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT A STRONG COLD FRONT 
WILL PASS THROUGH THE AREA LATE FRIDAY NIGHT/EARLY SATURDAY 
MORNING.  THE FRONT LOOKS TO GO THROUGH MOSTLY DRY DUE TO A LACK OF 
DEEP MOISTURE.  IF ANY PRECIP DOES OCCUR WITH THE FRONT IT SHOULD BE 
PRETTY SPOTTY AND LIGHT.  THE FRONT STALLS OVER NORTHERN ARKANSAS 
SATURDAY NIGHT WITH THE 850MB BAROCLINIC ZONE SITTING OVER SOUTHERN 
MISSOURI.  BOTH THE GFS AND ECMWF DEVELOP PRECIP IN RESPONSE TO 
ISENTROPIC LIFT OVER THE BAROCLINIC ZONE SATURDAY NIGHT.  CAN'T RULE 
OUT THUNDER AS THE GFS HAS SOME WEAK MUCAPE ACROSS THE SOUTHERN 1/3 
OF MISSOURI LATE SATURDAY NIGHT...BUT VALUES ARE GENERALLY LESS THAN 
100 J/KG SO HAVE LEFT THUNDER OUT FOR NOW.  STRONG LOW LEVEL 
BAROCLINICITY REMAINS IN PLACE SUNDAY THROUGH MONDAY AS A COUPLE OF 
SHORTWAVES SHOOT BY...EACH PRODUCING ANOTHER CHANCE FOR A ROUND OF 
PRECIP.  ALTHOUGH IT LOOKS LIKE WE WILL REMAIN ON THE COOL SIDE OF 
THE FRONT...INDICATIONS ARE THAT LOW LEVEL TEMPERATURES WILL REMAIN 
WARM ENOUGH TO KEEP ALL THE PRECIP LIQUID.  THAT BEING SAID...THE 
AIR UP ACROSS SOUTHERN CANADA AND THE DAKOTAS AT THAT TIME IS 
FORECAST TO BE VERY COLD.  IF THE HIGH ASSOCIATED WITH THAT AIR 
SHIFTS FURTHER SOUTHWARD THAN EXPECTED THERE COULD BE SOME WINTRY 
PRECIP ACROSS NORTHERN SECTIONS OF THE AREA BEFORE ALL IS SAID AND 
DONE.

CARNEY

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1231 PM CDT TUE MAR 12 2013

PRIMARY CONCERN FOR THE VALID TAF PERIOD WILL BE CEILINGS.
SECONDARY COLD FRONT IS FORECAST TO MOVE THROUGH THIS
AFTERNOON/EARLY EVENING WITH WEST WINDS SHIFTING TO THE NORTHWEST
AND BECOMING GUSTY. BEHIND THIS BOUNDARY...COMBINATION OF LOW
STRATUS ADVECTING SOUTHEAST AND DIURNAL CUMULUS DEVELOPING
OVERHEAD SHOULD YIELD INCREASING AND LOWERING OF CLOUDS THIS
AFTERNOON. MVFR CEILINGS BETWEEN 2000 AND 3000 FEET LOOK TO AFFECT
THE VALID TAF SITES THIS EVENING UNTIL EARLY TOMORROW MORNING.
WENT A BIT PESSIMISTIC AND KEPT MVFR CLOUD DECK A FEW HOURS PAST
WHAT GUIDANCE SUGGESTED...MAINLY DUE TO FACT THAT SIMILAR
SITUATIONS THIS COLD SEASON HAVE YIELDED SIMILAR RESULTS. BY MID
MORNING...SKIES AT ALL VALID TAF SITES SHOULD SCATTER AND THEN
CLEAR OUT WITH WINDS REMAINING OUT OF THE NORTHWEST AROUND 10-15
KTS.

SPECIFICS FOR KSTL...

PRIMARY CONCERN FOR THE VALID TAF PERIOD WILL BE CEILINGS.
SECONDARY COLD FRONT IS FORECAST TO MOVE THROUGH THIS
AFTERNOON/EARLY EVENING WITH WEST WINDS SHIFTING TO THE NORTHWEST
AND BECOMING GUSTY. BEHIND THIS BOUNDARY...COMBINATION OF LOW
STRATUS ADVECTING SOUTHEAST AND DIURNAL CUMULUS DEVELOPING OVERHEAD SHOULD
YIELD INCREASING AND LOWERING OF CLOUDS THIS AFTERNOON. MVFR
CEILINGS BETWEEN 2000 AND 3000 FEET LOOK TO AFFECT LAMBERT FIELD BEGINNING THIS
EVENING AND LASTING UNTIL EARLY TOMORROW MORNING. WENT A BIT
PESSIMISTIC AND KEPT MVFR CLOUD DECK UNTIL 1500 UTC OR A FEW HOURS
PAST WHAT GUIDANCE SUGGESTED...MAINLY DUE TO FACT THAT SIMILAR
SITUATIONS THIS COLD SEASON HAVE YIELDED SIMILAR RESULTS. BY MID-LATE
MORNING...SKIES SHOULD SCATTER AND THEN CLEAR OUT WITH WINDS
REMAINING OUT OF THE NORTHWEST AROUND 10-15 KTS.

OTHER CHANGE TO PREVIOUS FORECAST WAS TO ADD GUSTS THROUGH MOST OF
TONIGHT. UPSTREAM OBSERVATIONS WELL BEHIND SECONDARY COLD FRONT
INTO NEBARASKA AND THE DAKOTAS SUGGEST THIS POSSIBILITY AS DOES
NWP SOUNDINGS WITH DEEP MIXING CONTINUING THROUGHOUT THE NIGHT.

GOSSELIN

&&

.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS     29  44  31  59 /  20   0  10  20 
QUINCY          25  39  28  54 /  20   0  10  30 
COLUMBIA        22  44  30  62 /   5   0   5  10 
JEFFERSON CITY  23  43  29  63 /   5   0   5  10 
SALEM           31  39  27  50 /  20   0  10  30 
FARMINGTON      25  44  27  59 /   5   0   5  20 

&&

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

$$

WFO LSX