Severe Thunderstorm Warning 12, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
235 AM CST TUE MAR 25 2003

00Z MODELS APPEAR TO HAVE INITIALIZED WELL AND ARE VIRTUALLY
IDENTICAL OUT TO ABOUT 60 HOURS.  06Z SURFACE CHART SHOWS COLD FRONT
ALONG A LINE FROM JUST NORTH OF KJLN TO KCOU TO KSPI AND MOVING
STEADILY--IF SLOWLY--SOUTHEASTWARD.  THE FRONT MAY HAVE PICKED UP A
TINY BIT OF SPEED IN THE PAST FEW HOURS.  THINK ITS PROBABLY BEING
HELPED ALONG BY THE COLD POOL FROM THE WEAK CONVECTION ALONG IT.
THAT SAID...BOTH THE GFS AND ETA ARE DOING WELL WITH THE POSITION OF
THE FRONT AT 06Z THOUGH THE ETA IS SOMEWHAT LACKING IN MOISTURE AT
THE SURFACE WITH DEWPOINTS JUST A BIT TOO LOW AHEAD OF THE FRONT.

BOTH OF THE MODELS SLOW THE FRONT UP AFTER 12Z THIS MORNING...AND
THIS SEEMS REASONABLE SINCE CURRENT CONVECTION IS DYING OUT ACROSS
THE AREA.  WEAKENING COLD POOL SHOULD HELP THE FRONT ALONG TO A
POSITION JUST SOUTH OF THE STL METRO AREA GENERALLY FROM KUNO TO
JUST NORTH OF KFAM TO JUST NORTH OF KSAR TO JUST NORTH OF KSLO BY
12Z.  WE DONT EXACTLY HAVE A HUGE ARCTIC HIGH PUSHING THIS FRONT
SOUTHEASTWARD HERE...WINDS--WHEN NOT CONVECTIVELY INDUCED--ARE NOT
VERY STRONG BEHIND THE FRONT...RUNNING ONLY BETWEEN 10 TO 15 KTS.
10 TO 20 KT SOUTH TO SOUTHWESTERLY WINDS IN THE WARM SECTOR SHOULD
JUST ABOUT COUNTER THE COLD ADVECTION.  THEREFORE WOULD THINK THAT
THE COLD FRONT SHOULD BECOME NEARLY STATIONARY AFTER 12Z THIS
MORNING.  THIS WILL MAKE TEMPERATURE FORECASTS FAIRLY CHALLENGING
TODAY.  AMOUNT OF CLOUD COVER WILL ALSO ADD TO THE CHALLENGE TODAY.
MAV TEMPS LOOK TOO COOL ALONG THE EFFECTIVE FRONT AND IN THE WARM
SECTOR.  WILL LEAN MORE HEAVILY ON MET AND FWC NUMBERS HERE.  BEHIND
THE FRONT IN THE COOL AIR...MET LOOKS WAY TO WARM...SO SOMEWHERE
BETWEEN THE FWC AND MAV LIES THE TRUTH.  BOTH MODELS REFIRE
CONVECTION ALONG THE FRONT BY 18Z AND SLAM THE COOL AIR THROUGH THE
REMAINDER OF OUR CWFA BY 00Z.  GFS HAS A BIG CONVECTIVELY INDUCED
QPF BULLSEYE CENTERED JUST SOUTH OF KSTL  BETWEEN 18Z AND 00Z THIS
EVENING.  THERE SEEMS TO BE LESS GRID-SCALE FEEDBACK ON THE
ETA...AND IT THEREFORE LOOKS MORE BELIEVABLE.  OUR GOING POPS LOOK
PRETTY GOOD...WILL LIKELY DO JUST A LITTLE TWEAKING HERE AND THERE.

REMAINDER OF THE SHORT TERM LOOKS RATHER LESS COMPLICATED (NOTE:
FAMOUS LAST WORDS).  AFTER THE FRONT FINALLY PUSHES SOUTH AND EAST
OF OUR AREA WE SHOULD CLEAR OUT AND COOL OFF PRETTY GOOD.  ALL MOS
NUMBERS VERY CLOSE...SO WILL FOLLOW CLOSELY.  WILL ALSO LEAVE CHANCE
PRECIP IN SOUTHERN AND EASTERN ZONES FOR THIS EVENING AS THERE COULD
BE SOME POST FRONTAL PRECIP AS EVIDENCED BY SHOWERS BREAKING OUT
OVER WESTERN MISSOURI AT THIS TIME.  MET GUIDANCE FOR WEDNESDAYS
TEMPS LOOKS WAY TOO WARM...THINK MORE CONSERVATIVE FWC/MAV NUMBERS
ARE MORE IN LINE.  VARIOUS MOS TEMPS ON WEDNESDAY NIGHT ARE AGAIN
VERY CLOSE...SO WILL CONTINUE TO FOLLOW CLOSELY.

NEXT LOW FORMS SOMEWHERE IN WESTERN NEBRASKA ACCORDING TO THE MODELS
ON WEDNESDAY NIGHT/THURSDAY MORNING.  ETA TAKES A SOUTHERLY COURSE
INTO OKLAHOMA WITH THIS NEXT SYSTEM WHILE GFS TAKES THE MAIN SURFACE
WAVE NORTH INTO IOWA BY 00Z FRIDAY.  BY 84 HRS--12Z FRIDAY--THE
MODELS ARE LOOKING A LITTLE MORE SIMILAR. WITH THE ETA RAPIDLY
MOVING THE SURFACE LOW NORTHEASTWARD INTO WEST CENTRAL ILLINOIS.
GFS IS STILL FURTHER NORTH WITH THE WAVE IN WESTERN WISCONSIN.  IF
THIS WERE TWO MONTHS AGO IN THE DEAD OF JANUARY...I WOULD HAVE
LEANED TOWARD THE GFS SINCE IT PERFORMED BETTER OVERALL THIS
WINTER.  HOWEVER...SINCE WE SEEM TO HAVE TRANSITIONED RAPIDLY INTO A
SPRINGTIME PATTERN IN THE PAST COUPLE OF WEEKS I AM LESS THAN
CONFIDENT IN EITHER SOLUTION.  THE DIFFERENCE IN HIGH TEMPERATURES
ON THURSDAY COULD BE SIGNIFICANT DEPENDING ON WHICH SOLUTION WORKS
OUT.  THE ETA BUILDS A STRONG THERMAL RIDGE INTO SOUTHWESTERN AND
CENTRAL MISSOURI BY 18Z THURSDAY WITH 850MB TEMPS REACHING +12C
BETWEEN COLUMBIA AND KIRKSVILLE.  BY 00Z THE +12 ISOTHERM MOVES ALL
THE WAY INTO CENTRAL ILLINOIS.  THIS SEEMS A BIT TOO WARM TO ME.
LAST SUMMERS ETA FORECASTS COME TO MIND WHERE 60+ HOUR FORECASTS
WERE TOO WARM AT 850MB.  WILL GO NEAR MAV GUIDANCE AT THIS
TIME...AND MENTION MY CONCERNS TO THE DAY SHIFT SO THEY CAN WATCH
THE MODEL TRENDS...KEEPING IN MIND THAT THURSDAY COULD BE
SIGNIFICANTLY WARMER THAN CURRENT MAV FORECASTS.

.STL...NONE

CARNEY

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-251200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
630 AM CST MON MAR 24 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND EASTERN MISSOURI
AND WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE NEXT THREAT OF RAIN AFTER TONIGHT AND TOMORROW WILL BE FRIDAY
AFTERNOON AND FRIDAY NIGHT.  A DEEP STORM SYSTEM IS FORECAST TO
DEVELOP IN THE CENTRAL PLAINS ON THURSDAY AND MOVE EAST INTO THE
AREA FRIDAY AND FRIDAY NIGHT.  ITS STRENGTH WILL PULL A LOT OF GULF
MOISTURE NORTH INTO THE AREA. THERE WILL BE A CONSIDERABLE AMOUNT
OF RAIN POSSIBLE...AND THERE WILL BE SOME THREAT FOR POSSIBLE
SEVERE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

&&

MORE INFORMATION MAY BE OBTAINED AT...
HTTP://WWW.CRH.NOAA.GOV/LSX (ALL LOWER CASE)

PEDIGO