000
FXUS63 KLSX 130218
AFDLSX

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

.UPDATE...
ISSUED AT 915 PM CDT SUN MAY 12 2013

A BATCH OF HIGH CLOUDS HAS BEEN PUSHING SE ALONG THE MISSISSIPPI
RIVER THIS EVENING. BACK EDGE OF THESE CLOUDS IS NEAR STL...AND
SHOULD EXIT OUR CWA IN PLENTY OF TIME TO GIVE US A VERY CHILLY MAY NIGHT.
NO CHANGES PLANNED TO FROST ADVISORY AREA AS IT COVERS LOCATIONS
WITH THE GREATEST POTENTIAL FOR SEVERAL HOURS OF FAIRLY WIDESPREAD
FROST.

TRUETT

&&

.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 323 PM CDT SUN MAY 12 2013

WE HAVE ONE MORE NIGHT TO DEAL WITH THE UNSEASONABLY COOL
TEMPERATURES. THE ELONGATED SURFACE HIGH CURRENTLY CENTERED IN
WESTERN MO IS FORECAST TO SHIFT SOUTHEASTWARD TONIGHT AND BE
CENTERED IN THE WESTERN TENNESSEE VALLEY BY DAYBREAK ON MONDAY.
THIS SHOULD ALLOW FOR A FAIRLY GOOD PERIOD OF LIGHT WINDS TONIGHT
AND GOOD RADIATIONAL COOLING CONDITIONS. THE WAA CLOUDS THAT
LOOKED AS IF THEY COULD IMPACT THE FORECAST NO LONGER APPEAR TO BE
A PLAYER WITH THE FIRST BATCH REMAINING WELL TO THE SOUTHWEST AND
ANOTHER BATCH TONIGHT NOT MOVING INTO CENTRAL MO TIL NEAR DAWN.
SOME OF THE FAVORED SHELTERED SPOTS DROPPED INTO THE LOW-MID 30S
THIS MORNING WITH PATCHY FROST...AND SEE NO REASON FOR A SIMILAR
TREND TONIGHT GIVEN THE PATH OF THE SURFACE HIGH. THE COOLEST
READINGS SHOULD BE ACROSS THE EASTERN OZARKS AND FAR SW IL WHERE
LM30S LOOKS COMMON...AND A FEW OF THE BOTTOMS COULD FLIRT WITH 30.
I HAVE ISSUED A FROST ADVISORY FOR THIS AREA WHERE EXPECTING MORE
WIDESPREAD FROST...WITH PATCHY FROST EXPECTED IN THE REMAINDER OF
THE REGION WHERE MINS FALL TO 35-37. THE SURFACE HIGH WILL CONTINUE
TO RETREAT ON MONDAY WITH SOUTHERLY FLOW AND LOW LEVEL WAA BECOMING
ESTABLISHED AND TEMPS MODERATING. WE MAY ALSO HAVE TO DEAL WITH A FEW
BOUTS OF MID LEVEL WAA CLOUDS TRANSLATING FROM WEST TO EAST ACROSS
THE CWA. SOUTHERLY FLOW WILL PERSIST ON MONDAY NIGHT ALONG WITH
CONTINUE WAA AND THIS WILL RESULT IN MUCH WARMER TEMPERATURES THAN
THE LAST FEW NIGHTS/MORNINGS.

GLASS

.LONG TERM...(TUESDAY THROUGH NEXT SUNDAY)
ISSUED AT 323 PM CDT SUN MAY 12 2013

ALL SYSTEMS STILL APPEAR TO BE GO FOR A MONSTER WARM-UP ON TUESDAY
WITH HEIGHTS ALOFT RISING 140-160M FROM LATE MON THRU TUES AS THE
EASTERN TROF DEPARTS AND AN UPPER RIDGE BUILDS INTO THE MID MS
VALLEY. STRONG LOW LEVEL WAA WILL PERSIST AND H85 TEMPS ARE EVEN
WARMER AOA +20 DEGC BY 00Z WED ON THE BULK OF THE GUIDANCE. THE
MAJORITY OF THE MODEL SOUNDINGS SUGGEST MIXING TO AROUND 900
MB...WHICH COMBINED WITH SUNNY SKIES AND S/SW SURFACE WINDS
SUPPORT THE FORECAST OF HIGHS IN THE 85-90 RANGE. THE PRONOUNCED
SOUTHERLY FLOW WILL ALSO MARK THE BEGINNING OF LOW LEVEL MOISTURE
RETURN WHICH REALLY ACCELERATES TUESDAY NIGHT INTO WEDENSDAY AS
THE SOUTHERN STREAM UPPER TROF BEGINS TO IMPACT THE AREA...WITH
PWS NEARLY DOUBLING TO 1.3-1.5 INCHES BY WEDNESDAY EVENING. THE
ISSUE WE ARE STILL DEALING WITH IN THE WEDNESDAY AND BEYOND TIME
FRAME IS THE LOCATION OF THE EAST-WEST FRONT. THE NAM...LOCAL WRF
AND SREF ALL BRING THE BOUNDARY DOWN TO NEAR I-70 BY WEDNESDAY
EVENING WHILE THE ECMWF AND GFS ARE A GOOD DEAL FURTHER NORTH. THE
PRESENCE OF THE MIGRATORY UPPER TROF...ASSOCIATED INCREASE IN
MOISTURE AND INSTABILITY SUPPORTS A THREAT OF SHOWERS AND
THUNDERSTORMS ACROSS THE AREA BUT THERE SHOULD BE GREATER
CONCENTRATION INVOF OF THE FRONT...WHEREVER IT MAY ULTIMATELY
RESIDE. THE FRONT LOOKS TO EVENTUALLY LIFT BACK NORTH INTO THE
UPPER MS VALLEY WHATEVER THE CASE BY FRIDAY BUT THE PATTERN
REMAINS A BIT UNSETTLED. WHILE IT IS VERY FAR OUT INTO THE
FORECAST...IT IS INTERESTING TO NOTE THAT THERE ARE INDICATIONS OF
A DYNAMIC PROGRESSIVE UPPER TROF AND ATTENDANT SURFACE LOW/COLD
FRONT IMPACTING THE AREA SUNDAY/SUNDAY NIGHT.

GLASS

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 639 PM CDT SUN MAY 12 2013

RIDGE OF HIGH PRESSURE TO REMAIN OVER THE REGION TONIGHT WITH
CLEAR SKIES AND WINDS BECOMING LIGHT AND VARIABLE. THEN BY MID
MORNING ON MONDAY...RIDGE TO BEGIN TO MOVE OFF TO THE EAST
ALLOWING WINDS TO BECOME SOUTHERLY AND PICKUP BETWEEN 5 AND 10
KTS...WITH JUST A FEW DIURNAL CU/AC.

SPECIFICS FOR KSTL...RIDGE OF HIGH PRESSURE TO REMAIN OVER THE
REGION TONIGHT WITH CLEAR SKIES AND WINDS BECOMING LIGHT AND
VARIABLE BY 01Z. THEN BY 17Z MONDAY...RIDGE TO BEGIN TO
MOVE OFF TO THE EAST ALLOWING WINDS TO BECOME SOUTHERLY AND PICKUP
BETWEEN 5 AND 10 KTS...WITH JUST A FEW DIURNAL CU/AC.

BYRD

&&

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

RECORD LOWS

 5/13

ST LOUIS 40 (1971)

COLUMBIA 34 (1901)

QUINCY 35 (1971)


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...FROST ADVISORY FROM 3 AM TO 7 AM CDT MONDAY FOR CRAWFORD MO-IRON
     MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE. GENEVIEVE MO-
     WASHINGTON MO.

IL...FROST ADVISORY FROM 3 AM TO 7 AM CDT MONDAY FOR RANDOLPH IL-
     WASHINGTON IL.

&&

$$

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