Flash Flood in Illinois, January 31, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1245 PM CST THU JAN 31 2002

FIRST FORECAST CONCERN IS THIS EVENING/S POSSIBLE SEVERE AND
FLOODING POTENTIAL.
SECOND FORECAST CONCERN IS POSSIBLE SNOW EVENT NEXT WEEK.

INGREDIENTS SHAPING UP FOR AN INTERESTING SCENARIO LATE THIS
AFTERNOON INTO THE EVENING HOURS. A STRENGTHENING LOW LEVEL SW-NE
85H JET AROUND 50-60 KT IS PROGGED TO BE POSITIONED OVER THE CENTRAL
AND EASTERN PARTS OF THE REGION. ABOVE THIS LEVEL INCREASING SPEED
SHEAR IS ANTICIPATED THROUGH A NEARLY SATURATED LOWER AND MID TROP.
BEST UPPER LEVEL DYNAMICS WILL BE INCREASING ALSO ACROSS CENTRAL AND
EASTERN PARTS OF THE AREA BY 00Z. ANTICIPATING LINE OF CONCENTRATED
HEAVIER PRECIP/STORMS TO MOVE ACROSS SEMO LATE THIS
AFTERNOON...ACROSS FAR WEST KY AND SOUTHERN IL AROUND 00Z AND
SOUTHWEST INDIANA AND THE REST OF WEST KY IN THE EARLY EVENING. BEST
POTENTIAL FOR HEAVY WIDESPREAD PRECIP IS FOCUSED NORTH OF THE AREA.
WILL CONTINUE FFA FOR THIS EVENING WITH THE FOCUS NOW ON MORE OF
LOCALIZED FLOODING WITH HEAVIER THUNDERSTORM CELLS. EXPECT PRECIP TO
LAST NO MORE THAN 3 HRS AS STRATOFORM RAIN IN THE WAKE OF THE
CONVECTIVE LINE. THIS WILL MEAN AND END TIME OF EARLY EVENING
WEST...LATE EVENING CENTRAL AND AROUND MIDNIGHT EAST. SKIES SHOULD
CLEAR RAPIDLY AFTER CESSATION OF RAIN WITH THE DRY SLOT WRAPPING IN.
WRAP AROUND CLOUD COVER LOOKS TO MOVE BACK INTO AT LEAST THE
NORTHERN HALF OF THE AREA AROUND SUNRISE. WILL UNDERCUT MOS GUIDANCE
FOR TONIGHT AS NEITHER THE MAV NOR THE FWC SEEMS TO HAVE PICKED UP
ON THE DRY SLOT AND KEEP THE AREA CLOUDY ALL NIGHT. MESOETA BL TEMPS
LOOK MORE REASONABLE AND WILL GO WITH NUMBERS CLOSE TO THESE.

GOOD COLD AIR ADVECTION FRIDAY SHOULD KEEP TEMPS FROM INCREASING TOO
MUCH HIGHER THAN THE MORNING LOWS. WRAP AROUND CLOUD COVER IN THE
MORNING NORTH SHOULD CURTAIL WARMING TIL AROUND MID-DAY.

FRIDAY NIGHT THE AXIS OF THE SURFACE HIGH MOVES OVER THE AREA. WITH
LIGHT WINDS AND WET GROUND...FOG MIGHT BECOME A PROBLEM AREA. FOR
NOW WILL KEEP THIS AS A THOUGHT AND LEAVE A CLEAR FORECAST. MOS
GUIDANCE CURRENTLY IS RANGING FROM UPPER TEENS NORTH TO MID 20S
SOUTHEAST.

WEATHER PATTERN INTO THE WEEKEND IS LOOKING MUCH LIKE IT DID
YESTERDAY. ZONAL FLOW CONTINUES OVER THE AREA SATURDAY WITH DAYTIME
TEMPS A LITTLE WARMER THAN THOSE EXPECTED FRIDAY. SATURDAY NIGHT
INTO SUNDAY A SHORTWAVE TROUGH IS PROGGED TO DIP SOUTH ACROSS THE
GREAT LAKES REGION. THE SYSTEM STILL LOOKS TO BE LACKING ON MOISTURE
AND WHAT IS AVAILABLE IS FOCUSED NORTH OF THE AREA. AN INCREASE OF
CLOUDS NORTH MAY BE THE GREATEST IMPACT ON OUR WEATHER. WILL
CONTINUE TO TREND TEMPS A LITTLE WARMER.

NEXT QUESTION WILL BE TIMING OF A POSSIBLE SNOW EVENT NEXT WEEK.
MODEL GUIDANCE IS COMING INTO BETTER ALIGNMENT TODAY COMPARED TO
YESTERDAY. CONSENSUS TODAY IS SIMILAR TO THE PREVIOUS RUN OF THE
MRF...AND THE MRF ITSELF IS SIMILAR TO THE PREVIOUS RUN.  BUT THE
PROGGED STRENGTH OF THE SYSTEM AND 1000-500MB THICKNESS PATTERN ARE
DIFFERING FROM MODEL TO MODEL. ALSO...STILL A LITTLE CONCERNED THAT
THE MODEL SPEED OF THE SYSTEM MIGHT BE TOO QUICK. AS SUCH WILL
CONTINUE TO MENTION SNOW POSSIBILITIES ON WEDNESDAY. IF THE EVENT IS
AS SIGNIFICANT AS THE MRF SUGGEST...DAYTIME HIGHS WILL NOT REACH FMR
VALUES WITH A SNOWPACK ON THE GROUND...SO WILL CONTINUE TREND OF
HIGHS LOWER THAN GUIDANCE AFTER THE EXPECTED SNOWFALL DAYS.

.PAH...CONTINUE FFA ALL COUNTIES FOR EVENING.

DFS