000
FXUS63 KLSX 222035
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
335 PM CDT WED MAY 22 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 314 PM CDT WED MAY 22 2013

A FEW SHOWERS THAT POPPED UP ALONG AND AHEAD OF A REINFORCING COLD
FRONT WILL CONTINUE TO GRADUALLY MOVE EASTWARD...AND ANY LINGERING
SHOWERS SHOULD TAPER OFF QUICKLY AFTER SUNSET THIS EVENING WITH A
LOSS OF DIURNAL HEATING. THE LARGE LOW CONTINUING TO SPIN OVER THE
UPPER MIDWEST/GREAT LAKES WILL ACT TO KEEP MUCH OF THE REGION
UNDER PARTLY TO MOSTLY CLOUDY SKIES TONIGHT...THUS HAVE NOT GONE TOO
FAR BELOW GUIDANCE ON TONIGHT`S LOWS...WHICH WILL GENERALLY BE IN
THE LOW TO MIDDLE 50S ACROSS THE AREA. OBS TODAY OVER EASTERN AND
SOUTHEASTERN NEBRASKA HAVE INDICATED SOME POCKETS OF LIGHT
RAIN/DRIZZLE OCCURRING ON THE BACK SIDE OF THE LOW...THUS CANNOT
RULE OUT SOME LIGHT PRECIPITATION OVER THE NORTHERN TIER OF THE CWA
AS THE LOW BEGINS TO FINALLY LIFT NORTHEAST...MAINLY DURING THE LATE
OVERNIGHT HOURS TO JUST BEFORE DAYBREAK.

PHILLIPSON

.LONG TERM...(THURSDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 314 PM CDT WED MAY 22 2013

THU THROUGH FRI NIGHT...VORT MAXES MOVING ACROSS THE AREA TOMORROW
MAY SUPPORT ISOLATED SHOWERS HOWEVER THE TIMING OF THE VORT MAXES
ARE CURRENTLY FCST TO BE TEMPORALLY OUT OF SYNC WITH DIURNAL HEATING
WHICH WOULD TEND TO LIMIT PCPN COVERAGE. SOME CLOUD COVER SHOULD
PERSIST TOMORROW WITHIN CYCLONIC FLOW ALOFT IN THE WAKE OF A
DEPARTING LOW PRESSURE SYSTEM. A STRONG SFC HIGH THEN BUILDS INTO
THE MIDWEST AND BRINGS COOLER AIR TO MO/IL...EFFECTIVELY PUSHING A
FNTL BDRY IN SRN MO/NRN AR SWD AS A CDFNT. THE COOLEST OVERNIGHT
LOWS OUT OF THE NEXT SEVERAL DAYS WILL PROBABLY OCCUR LATE
TOMORROW NIGHT/EARLY FRI MORNING. TEMPERATURES SHOULD REMAIN
SEASONABLY COOL ON FRI UNDER THE INFLUENCE OF COOL ELY SFC FLOW.
GENERALLY DRY CONDITIONS ARE EXPECTED THROUGH FRI NIGHT HOWEVER
NOCTURNAL CONVECTION DRIVEN BY THE LLJ MAY CLIP THE NWRN CWA ON
LATE FRI NIGHT.

SAT THROUGH TUE...SFC WINDS WILL GRADUALLY BECOME SLY ACROSS THE CWA
AROUND THE BACK SIDE OF THE SFC HIGH ONCE IT SHIFTS FARTHER EWD. A
DVLPG LOW OVER THE PLAINS WILL REORIENT A BAROCLINIC ZONE SUCH THAT
IT STRETCHES THROUGH ERN KS AND WRN MO AS A WMFNT. TEMPERATURES WILL
WARM UP OVER THE WEEKEND AS THIS BDRY LIFTS INTO CENTRAL MO WITH THE
TEMPERATURE INCREASE AIDED BY THE STRONG SUN ANGLE AT THIS TIME OF
YEAR. MODELS ARE HINTING AT A FEW ILL-DEFINED VORT MAXES MOVING
ACROSS THE AREA OVER THE WEEKEND WHICH MAY SUPPORT SCT
THUNDERSTORMS. ADDITIONALLY...UPSTREAM NOCTURNAL MCS DVLPMT MAY ALSO
AFFECT OUR AREA THIS WEEKEND...EITHER AS DECAYING REMNANTS MOVING
INTO THE CWA OR BY GENERATING AN MCV WHICH FOCUSES TSRA DVLPMT
DURING THE FOLLOWING AFTN. POP12 CLIMATOLOGY FOR THIS TIME OF YEAR
IS AROUND 30 PERCENT AND THAT LOOKS REASONABLE GIVEN THE LACK OF
WELL-DEFINED FEATURES TO FOCUS PCPN DVLPMT AND THE UNCERTAINTY
REGARDING THE EFFECTS OF UPSTREAM MCS ACTIVITY. THE UPPER AIR
PATTN OVER THE CENTRAL PART OF THE COUNTRY WILL SHIFT FM RIDGING
TO SW FLOW BY THE MIDDLE OF THE WEEK AFTER A SHORTWAVE MOVES INTO
THE SWRN CONUS.

KANOFSKY

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1232 PM CDT WED MAY 22 2013

A COLD FRONT CURRENTLY MOVING THROUGH METRO AREA TAF SITES WILL
CONTINUE ITS EASTWARD PROGRESSION THIS AFTERNOON...WITH SHOWERS
POSSIBLE THROUGH SUNSET THIS EVENING. WHILE THUNDER CANNOT BE
COMPLETELY RULED OUT...CONFIDENCE IS LOW GIVEN THE LACK OF
INSTABILITY ACROSS THE AREA...AND THUS HAVE CONTINUED WITH VCSH
MENTION FOR AREA TAF SITES. MVFR CIGS WILL MOVE SOUTH INTO THE
AREA OVERNIGHT TONIGHT AND TOWARD DAYBREAK ON THURSDAY...WITH
WINDS VEERING TO THE NORTHWEST ON THURSDAY MORNING.

SPECIFICS FOR KSTL...

SHOWERS ARE POSSIBLE THROUGH THE AFTERNOON AT KSTL...AND THOUGH
THUNDER IS POSSIBLE...CONFIDENCE IS LOW GIVEN A LACK OF
INSTABILITY TO WORK WITH. THUS...HAVE CONTINUED THE VCSH MENTION
FOR THE AFTERNOON. OVERNIGHT TONIGHT AND TOWARD THURSDAY
MORNING...MVFR CIGS WILL MOVE SOUTH OVER THE TERMINAL...WITH SLOW
BUT GRADUAL IMPROVEMENT EXPECTED BY THE AFTERNOON. WINDS WILL
VEER TO THE NORTHWEST THURSDAY...AND COULD BECOME GUSTY DURING THE
AFTERNOON.

JP

&&

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

$$

WFO LSX