000
FXUS63 KLSX 121709
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1209 PM CDT SUN MAY 12 2013

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 314 AM CDT SUN MAY 12 2013

TRANQUIL AND DRY WEATHER CAN BE EXPECTED TODAY AS THE SFC RIDGE OVER
THE PLAINS MOVES SEWD THROUGH MO.  LITTLE CLOUD COVER IS FORECAST
TODAY...EXCEPT A FEW DIURNAL CUMULUS CLOUDS THIS AFTN...MAINLY E OF
THE MISSISSIPPI RIVER.  DESPITE FULL MAY SUNSHINE HIGH TEMPERATURES
WILL BE ABOUT 10 DEGREES BELOW NORMAL AS 850 MB TEMPERATURES ARE
FORECAST TO BE ONLY -2 TO ZERO DEGREES C ACROSS OUR FORECAST AREA AT
18Z SUN.

GKS

.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 314 AM CDT SUN MAY 12 2013

(TONIGHT THROUGH TUESDAY)

DRY WEATHER IS EXPECTED THROUGH MIDWEEK AS HEIGHTS RISE BEHIND EXITING
LONGWAVE TROUGH.  WARM FRONT WILL LIFT NORTHEASTWARD ACROSS THE AREA
ON MONDAY NIGHT WITHOUT ENOUGH FORCING OR INSTABILITY TO PRODUCE ANY
MID-MAY NOCTURNAL THUNDERSTORMS.

DEWPOINTS HAVE FALLEN INTO THE UPPER 20S AS FAR SOUTH AS STL EARLY
THIS MORNING.  THIS DRY AIRMASS WILL REMAIN IN PLACE THROUGH TONIGHT
WHEN THE SURFACE RIDGE PASSES THROUGH THE AREA.  THIS WILL SET UP
DECENT RADIATIONAL COOLING TONIGHT...PARTICULARLY OVER THE EASTERN
HALF OF THE CWA WHERE TEMPERATURES WILL FALL LOW ENOUGH FOR 1-3
HOURS TO CAUSE SOME PATCHY FROST. MONDAY WILL START A WARM-UP AS
SURFACE RIDGE MOVES OFF TO THE EAST. MIXING DOWN 850MB
TEMPERATURES SUPPORT THE GFS/NAM MOS GUIDANCE. SOUTHWEST WINDS ON
TUESDAY STILL FAVOR A WARM DAY WITH 850MB TEMPERATURES IN 19-22C
RANGE. FORECAST SOUNDINGS SHOW MIXING UP TO 900MB WHICH STILL
FAVORS HIGHS IN THE 85 TO 90 DEGREE RANGE.

(WEDNESDAY THROUGH SATURDAY)

GFS HAS COME INTO AGREEMENT WITH WHAT THE ECMWF HAS BEEN SHOWING THE
PAST TWO DAYS THAT THE UPPER LOW CURRENTLY OVER NORTHWESTERN MEXICO
WILL NOT MERGE WITH NORTHERN STREAM LATER THIS WEEK. INSTEAD IT
WILL SLOWLY LIFT NORTHEASTWARD INTO THE CENTRAL PLAINS BY
WEDNESDAY. THE GFS IS STILL ABOUT 12 HOURS FASTER IN OPENING UP
THE LOW AND MOVING IT ACROSS MO/IL ON THURSDAY. THE LACK OF
PHASING BETWEEN THE NORTHERN STREAM AND THE UPPER LOW KEEPS THE
GFS FROM MOVING A COLD FRONT SOUTH OF THE CWA ON THURSDAY. WILL
KEEP HIGH CHANCE OF SHOWERS/THUNDERSTORMS WEDNESDAY/THURSDAY AS
THE TROUGH/UPPER LOW MOVES THROUGH. THEN KEPT CHANCE OF RAIN INTO
EARLY NEXT WEEKEND AS ATMOSPHERE WILL REMAIN UNSTABLE WITH A
QUASI-STATIONARY FRONT LYING OVER NORTHERN MO INTO CENTRAL IL.

BRITT

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1206 PM CDT SUN MAY 12 2013

VFR AND DRY THRU THE PERIOD. NWLY WINDS WITH GUST TO NEAR 20 KTS
IN SOME LOCATIONS WILL DIMINISH EARLY THIS EVE TO BECOME LIGHT AND
VRB OVERNIGHT WITH CLEAR SKIES. SLY WINDS WILL PICK UP LATE MON
MORNING WITH A SCT TO BKN DECK AROUND 12 KFT POSSIBLE.


&&

.CLIMATE...
ISSUED AT 328 PM CDT FRI MAY 10 2013

RECORD LOWS

5/125/13

ST LOUIS39 (1960)40 (1971)

COLUMBIA35 (1892)34 (1901)

QUINCY35 (1960)35 (1971)


&&

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

$$

WFO LSX