Severe Thunderstorm Warning 338, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1025 AM CST WED JAN 12 2005

.DISCUSSION...

FORECAST ON TRACK AS SURFACE FRONT ACROSS WESTERN MISSOURI IS
LIGHTING UP WITH CONVECTION. TEMPERATURES ON THERE WAY TO TIEING IF
NOT BREAKING THE RECORD OF 70F AT KSTL. WARM FRONT JUST PASSED KUIN
AND NOW MOST OF CWA IN WARM SECTOR OF APPROACHING SYSTEM. FLOOD
WATCH WILL REMAIN IN EFFECT GIVEN EXPECTATION OF +TSRA LATE THIS
AFTERNOON AND THIS EVENING WITH APPROACHING COLD FRONT. CWA REMAINS
IN SLIGHT RISK OF SEVERE THUNDERSTORMS GIVEN SUFFICIENT INSTABILITY
...MOISTURE...AND SHEAR. MAIN THREAT WILL BE LARGE HAIL AND DAMAGING
WINDS...AS SQUALL LINE PROPOGATES EAST ACROSS THE AREA THIS EVENING.

...PREVIOUS DISCUSSION...

WE HAVE BEEN PONDERING ABOUT THE POTENTIAL FOR SOME POST-FRONTAL
WNTRY PCPN FOR AT LEAST THE LAST 4-5 DAYS.  SVRL DAYS AGO THERE WAS
STILL A MID LVL CIRCLN PROGGED AND THE PROSPECT LOOK QUITE GOOD.
WHILE THE UPR WAVE IS FCST TO BE MUCH LESS AMPLIFIED NOW THERE ARE
STILL INDICATIONS THAT A SEPARATE DETACHED NE-SW ORIENTED BAND OF
LGT PCPN WILL OCCUR WELL INTO THE COLD AIR ASSOCD WITH LOW-MID LVL
FRONTOGENTICAL FORCING.  BOTH THE GFS AND ETA SUGGEST THIS.  THIS
BAND SHUD WEAKEN AS IT TRANSLATES EWD ON THURS MORNING AS THE
FRONTOGENETICAL FORCING IS PROGGED TO WEAKEN. AS MY CONFIDENCE IS
NOT OVERWHLEMING WITH THIS SCENARIO I HAVE CONTINUED WITH JUST CHC
POPS INTO THURSDAY.  ANY SNOW AMOUNTS LOOK LGT ATTM.

STILL EXPECTING THURSDAY TO BE BLUSTERY AND COLD WITH MORNING
HIGHS AND STEADY TO FALLING TEMPS.  ARCTIC HI PRES PRETTY MUCH
DOMINATES BEGINNING LATE THURS INTO EARLY NEXT WEEK.  DURING THIS
TIME FRAME WE ARE CONTINUING TO WATCH A SERIES OF WK DISTURBANCES
IN THE BROAD CYCLONIC MID/UPR FLOW.  THERE IS A INCREASING TREND
THAT THE ASSOCD LOW/MID LVL FRONTOGENETICAL FRCG AND WK QG FORCING
WILL GENERATE SOME PERIODIC W-E SNOW BANDS.  PRIND ARE THESE WILL
REMAIN ALONG OR NORTH OF THE IA/MO BORDER WITH JUST CLOUDS FURTHER
SOUTH...BUT BY LATE SAT NGT INTO SUN EVENING THE GFS SUGGESTS
THAT THE FOCUS WILL SHIFT SOUTH THRU THE CWFA.  ATTM I
HAVE INCLUDED A CHC OF SNOW.  IF IT PANS OUT A BAND OF LGT-MOD
SNOW IS CERTAINLY QUITE PSBL WITH HIGH LIQUID TO SNOW RATIOS.
&&

.LSX WATCHES/WARNINGS/ADVISORIES...
.MO...FLOOD WATCH FROM 6 AM WEDNESDAY UNTIL 4 AM THURSDAY FOR MOZ018...
      MOZ019...MOZ026...MOZ027...MOZ034...MOZ035...MOZ036...
      MOZ041...MOZ042...MOZ047...MOZ048...MOZ049...MOZ050...
      MOZ051...MOZ052...MOZ059...MOZ060...MOZ061...MOZ062...
      MOZ063...MOZ064...MOZ065...MOZ072...MOZ073...MOZ074...
      MOZ075...MOZ084...MOZ085...MOZ099.
.IL...FLOOD WATCH FROM 6 AM WEDNESDAY UNTIL 4 AM THURSDAY FOR ILZ058...
      ILZ059...ILZ060...ILZ064...ILZ065...ILZ069...ILZ070...
      ILZ074...ILZ079...ILZ095...ILZ096...ILZ097...ILZ098...
      ILZ099...ILZ100...ILZ101...ILZ102.

&&

CVKING/GLASS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
226 PM CST WED JAN 12 2005

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-131200-
ADAMS IL-AUDRAIN-BOND IL-BOONE-BROWN-CALHOUN IL-CALLAWAY-CLINTON IL-
COLE-CRAWFORD-FAYETTE IL-FRANKLIN-GASCONADE-GREENE IL-IRON-JEFFERSON-
JERSEY IL-KNOX-LEWIS-LINCOLN-MACOUPIN IL-MADISON-MADISON IL-MARION-
MARION IL-MONITEAU-MONROE-MONROE IL-MONTGOMERY-MONTGOMERY IL-OSAGE-
PIKE-PIKE IL-RALLS-RANDOLPH IL-REYNOLDS-SHELBY-ST CHARLES-
ST CLAIR IL-ST FRANCOIS-ST LOUIS-ST LOUIS CITY-STE GENEVIEVE-WARREN-
WASHINGTON-WASHINGTON IL-
226 PM CST WED JAN 12 2005

...FLOOD WATCH IN EFFECT THROUGH TONIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF CENTRAL AND NORTHEAST
MISSOURI AND WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TONIGHT

A LINE OF SHOWERS AND THUNDERSTORMS AHEAD OF A POWERFUL COLD
FRONT WILL MOVE ACROSS THE REGION TONIGHT. SOME OF THE THUNDERSTORMS
MAY REACH SEVERE LIMITS...WITH PENNY SIZE HAIL AND WIND GUSTS GREATER
THAN 58 MPH. THE THUNDERSTORMS WILL ALSO BE CAPABLE OF PRODUCING
LOCALLY HEAVY RAINFALL AND POSSIBLY FLASH FLOODING. SOME LOCAL RIVERS
WILL RESPOND TO THIS ADDITIONAL RAINFALL BY RISING NEAR OR ABOVE
FLOOD STAGE IN MISSOURI...AND CREST HIGHER THAN PREVIOUSLY EXPECTED
IN ILLINOIS.

COLDER AIR WILL MOVE INTO THE REGION TOWARD MORNING...MIXING THE
RAIN WITH SNOW. LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE IS A CHANCE OF LIGHT SNOW ON THURSDAY MORNING. LITTLE IF ANY
SNOW ACCUMULATION IS EXPECTED.

VERY COLD AIR WILL DOMINATE THE REGION THROUGH THE WEEKEND. WIND
CHILL VALUES MAY PERIODICALLY DROP BELOW ZERO DEGREES DURING THIS
PERIOD. THERE IS ALSO A CHANCE OF SNOW ON SUNDAY AND SUNDAY NIGHT...
WITH THE POTENTIAL FOR LIGHT ACCUMULATION.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ASKED TO RELAY RAINFALL AMOUNTS AND ANY SEVERE WEATHER
REPORTS TONIGHT TO THE NATIONAL WEATHER SERVICE.

CVKING