Areal Flood Advisory 21, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
305 PM CDT WED MAY 26 2010

.DISCUSSION...
/304 PM CDT WED MAY 26 2010/

SCATTERED SHOWERS AND THUNDERSTORMS HAVE POPPED UP ONCE AGAIN
TODAY...MAINLY ALONG AND EAST OF A QUINCY TO STEELEVILLE LINE...AND
SLOWLY DRIFTING TO THE SOUTH. SO MAIN FORECAST ISSUE IN THE SHORT
TERM IS DEALING WITH THE DAILY DIURNAL CHANCES OF SHOWERS AND
THUNDERSTORMS...BEFORE STRONGER RIDGE BUILDS IN ON FRIDAY...DRYING
THINGS OUT AND SURPRESSING ANY ACTIVITY FOR THE FIRST HALF OF THE
HOLIDAY WEEKEND.

ACTIVITY WILL PERSIST THIS EVENING...MAINLY ACROSS EASTERN HALF OF
CWA...BEFORE SLOWLY DIMINISHING. OTHERWISE...EXPECT MILD AND HUMID
CONDITIONS WITH LOWS ONLY IN THE LOW TO MID 60S TONIGHT.

ON THURSDAY...WILL SEE A DECENT SHORTWAVE SLIDE SOUTH THROUGH THE
AREA WITH AN EVEN BETTER CHANCE OF SHOWERS AND THUNDERSTORMS
DEVELOPING...THOUGH DO NOT EXPECT ANY WIDESPREAD SEVERE WEATHER...
JUST SOME ISOLATED CHANCES OF HAIL...GUSTY WINDS OR VERY HEAVY
RAINFALL. ANOTHER WARM DAY WITH HIGH TEMPERATURES IN THE LOW TO MID
80S.

BY THURSDAY EVENING...ACTIVITY WILL FINALLY COME TO AN END AS DECENT
SURFACE RIDGE BUILDS IN WITH DRIER AIR SINKING SOUTH. TEMPS WILL DIP
INTO THE UPPER 50S WITH CLEARING SKIES.

DRY WEATHER TO CONTINUE THROUGH SUNDAY WITH HIGH TEMPS IN THE 80S
EACH DAY. HOWEVER...ANOTHER WEATHER SYSTEM WILL APPROACH THE REGION
SUNDAY NIGHT WITH A COLD FRONT SLIDING THROUGH AREA AND STALLING
JUST SOUTH OF THE FORECAST AREA BY MONDAY. STILL NOT CONFIDENT ON
EXACT TIMING OF THIS SYSTEM SO HAVE SILENT 20 POPS SUNDAY NIGHT WITH
LOW CHANCE POPS MONDAY...MEMORIAL DAY. WITH FRONT STALLED TO OUR
SOUTH COULD SEE ADDITIONAL ACTIVITY OVER SOUTHEASTERN PORTIONS OF
FORECAST AREA ON TUESDAY.

BYRD
&&

.AVIATION...
/104 PM CDT WED MAY 26 2010/

AMS-TYPE THUNDERSTORMS WILL CONTINUE TO THREATEN TAFS THROUGHOUT
THE PERIOD. IN THE ABSENCE OF SYNOPTIC SCALE FORCING CONVECTIVE
TRENDS WILL PRIMARILY BE DRIVEN BY STORM INTERACTIONS/OUTFLOW
BOUNDARIES...WHICH NECESSIATES USING NOWCAST TECHNIQUES TO PIN
DOWN SPECIFICS ONCE THE CONVECTION GETS GOING. WILL INTITIALLY
HIGHLIGHT THREAT WITH CB CLOUD GROUPS AT UIN AND COU...AND VCTS AT
STL AND SUS DUE TO DEVELOPMENT THAT OCCURRED OVER STL CITY JUST
BEFORE 18Z. GREATEST COVERAGE SHOULD BE TIED TO MAX AFTERNOON
HEATING SO HAVE CONTINUED PREVIOUS FORECAST TRENDS OF ENDING TSRA
THREAT AT 03Z...HOWEVER AS HAS BEEN THE CASE THE PAST FEW EVENINGS
STORMS MAY CERTAINLY LINGER WELL PAST THAT TIME FRAME. WILL LET
EVENING SHIFT FINE TUNE THOSE DETAILS.

SPECIFICS FOR KSTL...IN ADDITION TO ABOVE REASONING...ROBUST STORM
THAT FORMED NEAR DOWNTOWN HAS PRODUCED A WELL-DEFINED OUTFLOW
BOUNDARY THAT THE TDWR DATA INDICATES IS PROPAGATING WNW TOWARD
STL...SO HAVE INCLUDED AN HOUR OR TWO OF SE WIND BEGINNING AT
1830Z.

TRUETT
&&

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

WFO LSX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
340 PM CDT WED MAY 26 2010

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-271200-
GREENE IL-MACOUPIN IL-MONTGOMERY IL-BOND IL-FAYETTE IL-CLINTON IL-
MARION IL-WASHINGTON IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL-
CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-KNOX MO-
LEWIS MO-SHELBY MO-MARION MO-MONROE MO-RALLS MO-PIKE MO-BOONE MO-
AUDRAIN MO-MONITEAU MO-COLE MO-OSAGE MO-CALLAWAY MO-MONTGOMERY MO-
LINCOLN MO-GASCONADE MO-WARREN MO-ST. CHARLES MO-FRANKLIN MO-
ST. LOUIS MO-ST. LOUIS CITY MO-JEFFERSON MO-CRAWFORD MO-
WASHINGTON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO-IRON MO-
MADISON MO-REYNOLDS MO-
340 PM CDT WED MAY 26 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND
CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TONIGHT

SCATTERED...HIT AND MISS...THUNDERSTORMS ARE EXPECTED THROUGH
TONIGHT. ALTHOUGH NO ORGANIZED OR WIDESPREAD SEVERE WEATHER IS
EXPECTED...A FEW STORMS MAY BECOME STRONG TO SEVERE PRODUCING
HAIL AND STRONG GUSTY WINDS. DUE TO THE SLOW MOVEMENT OF THE
STORMS AND THE MOISTURE IN THE AIR HEAVY RAINS AND LOCALIZED
FLOODING IS ALSO POSSIBLE.

MODERATE FLOODING IS OCCURRING AT CHESTER ALONG THE MISSISSIPPI
RIVER.  PLEASE SEE THE APPROPRIATE FLOOD STATEMENT FOR SPECIFIC
DETAILS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE CHANCE FOR THUNDERSTORMS WILL CONTINUE ON THURSDAY. THERE IS
ANOTHER CHANCE FOR THUNDERSTORMS ON MONDAY.

MODERATE FLOODING IS EXPECTED TO CONTINUE AT CHESTER ALONG THE
MISSISSIPPI RIVER UNTIL SATURDAY MORNING. PLEASE SEE THE
APPROPRIATE FLOOD STATEMENT FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE REQUESTED TO REPORT ANY HAIL..STRONG WIND GUSTS...OR
RAINFALLS IN EXCESS OF ONE INCH.

&&

FOR A GRAPHICAL VERSION OF THIS INFORMATION SEE OUR
WEBPAGE AT (LOWERCASE)... HTTP://WWW.WEATHER.GOV/LSX/?N=HWO1

BYRD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
546 PM CDT WED MAY 26 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 PM     HEAVY RAIN       SHIPMAN                 39.12N  90.05W
05/26/2010  M1.75 INCH       MACOUPIN           IL   AMATEUR RADIO

            AMATEUR RADIO OPERATOR REPORTED 1.75 INCHES OF RAINFALL
            BETWEEN 400 AND 530 PM

&&

PRZYBYLINSKI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
550 PM CDT WED MAY 26 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0549 PM     HAIL             ST. LOUIS               38.64N  90.24W
05/26/2010  E0.50 INCH       ST. LOUIS CITY     MO   TRAINED SPOTTER

            HAIL REPORTED AT SAINT LOUIS UNIVERSITY

&&

PHILLIPSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
608 PM CDT WED MAY 26 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0607 PM     HAIL             BRIDGETON               38.77N  90.43W
05/26/2010  E0.25 INCH       ST. LOUIS          MO   AMATEUR RADIO

            PEA SIZE HAIL AT PAGE AND LINDBERG

&&

PRZYBYLINSKI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
609 PM CDT WED MAY 26 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0609 PM     HAIL             FLORISSANT              38.80N  90.32W
05/26/2010  E0.25 INCH       ST. LOUIS          MO   TRAINED SPOTTER

&&

PHILLIPSON

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