Hail in Illinois, April 20, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
355 PM CDT WED APR 20 2005

.SYNOPSIS...
12Z UA ANALYSIS SHOWED A CLOSED H5 LOW OVER THE INTER MOUNTAIN
REGION WITH WEAK S/W RIDGING FROM THE WESTERN GULF INTO THE CENTRAL
PLAINS. NW FLOW WAS IN PLACE TO OUR N WITH S/W ENERGY ROTATING
THROUGH THE NRN GREAT LAKES.  AT THE SURFACE...IT APPEARS THAT THE
STATIONARY FRONT REMAINS FROM SRN IA INTO WEST CENTRAL IL...ALTHOUGH
THE BOUNDARY WAS GETTING DIFFICULT TO LOCAT WITH OUTFLOWS FROM THE
WEST CENTRAL IL CONVECTION DISRUPTING THE SURFACE WINDS.  EARLY
MORNING CONVECTIVE COMPLEX RIDING ALONG THE STATIONARY FRONT DIED
OUT AS IT APPROACHED EASTERN IA.  MORNING SUN OVER SOUTHEAST IA AND
NW IL DESTABILIZED THE AIRMASS ENUF TO ALLOW THE CONVECTION TO
REFIRE ALONG AND EAST OF THE MS RIVER AROUND NOON.  SO FAR ONLY A
FEW STORMS HAVE SHOWN AND SIGNS OF SEVERE POTENTIAL.  LOOKS LIKE
WEAK SHEAR THROUGH THE MID LEVELS WAS CONTRIBUTING TO THE PULSEY
NATURE OF THE CONVECTION.

&&

.SHORT TERM (TODAY AND TONIGHT)...
MAIN CONCERN IN THE NEAR TERM WILL BE THE PCPN TRENDS TONIGHT NEAR
THE STATIONARY/COLD FRONT...THEN SHIFTING TO PCPN THREAT AHEAD OF
MID LEVEL LOW EJECTING OUT OF THE INTERMOUNTAIN REGION THURSDAY AND
FRIDAY.  EVEN THOUGH MOST OF THE CONVECTION IS EXITING THE EASTERN
CWA AT THIS TIME...WILL CONTINUE CHANCE POPS OVER THE SOUTHERN HALF
OF THE CWA THIS EVENING. MODELS SHOW H5 VORT MOVING THROUGH CWA LATE
THIS AFTERNOON AND THIS EVENING WHICH IS SUPPORTED BY H5 PROFILER
PLOT AND 3HR SURFACE PRESSURE FALLS CENTERED JUST AHEAD OF THE WAVE
PROVIDING SOME FORCING ALONG THE SURFACE BOUNDARY AS IT SAGS SOUTH.
PCPN THREAT DUE TO THESE FEATURES SHOULD BE NIL BY MID EVENING.
LATER TONIGHT...MODELS SHOW H8 BOUNDARY OVER THE SRN CWA WITH
POTENTIAL FOR MCS DEVELOPMENT OVER NRN KS/SRN NE AHEAD OF DEVELOPING
OK PANHANDLE LOW.  THERE IS POTENTIAL FOR SOME OF THE PCPN TO MOVE
EAST ALONG THE H8 FRONT INTO EASTERN IA/NRN MO LATE
TONIGHT...ALTHOUGH DIFFLUENT H8 FLOW OVER CENTRAL IA MAY LIMIT THE
EASTERN EXTENT.

&&
.LONG TERM (TUESDAY NIGHT THROUGH MONDAY)...
MODELS ARE IN GOOD AGREEMENT EJECTING THE MID LEVEL SYSTEM INTO THE
PLAINS BY LATE THURSDAY...THEN MOVING IT EAST THROUGH THE MID/LOWER
MS VALLEY ON FRIDAY.  HAVE BUMPED POPS INTO THE LIKELY CATEGORY
THURSDAY NIGHT AND CONTINUED INTO FRIDAY AS A NRN STREAM S/W DROPS
THROUGH THE REGION FRIDAY AND PHASES WITH SRN STREAM LOW. TRACK OF
DEVELOPING SURFACE LOW THROUGH NRN MO/CENTRAL IL SUGGEST THE AREAS
ALONG AND N OF I80 ARE IN LINE FOR A WIDESPREAD PCPN EVENT. THURSDAY
THROUGH FRIDAY.  TEMPS WILL BE AN ISSUE BEHIND THE SYSTEM.  THE GFS
DROPS H8 TEMPS OF -8 INTO THE EASTERN CWA FRIDAY NIGHT/SATURDAY.
HOWEVER...ITS THE ODD MODEL OUT WITH THE ETA/ECMWF SEVERAL DEGREES
WARMER. ALL MODELS SUGGEST COLDER TEMPS THAN CURRENTLY FCST SO...CUT
TEMPS SUM FRIDAY/SATURDAY BUT NOT AS MUCH AS THE GFS SUGGESTS.

MODELS HAVING SOME DIFFICULTY HANDLING NW FLOW THAT SETS UP OVER THE
ERN U.S. INTO THE MIDDLE OF NEXT WEEK.  FOR THE MOST PART WENT WITH
A GFS/ECMWF BLEND.  KEPT CHANCE POPS FOR TUESDAY WITH MODELS SHOWING
S/W DROPPING THROUGH REGION IN NORTHWEST FLOW OTHERWISE.  TEMPS
SHOULD BE CLOSER TO NORMAL FOR THE END OF APRIL.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

DLF

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
500 AM CDT WED APR 20 2005

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-211000-
BENTON IA-BUCHANAN IA-BUREAU IL-CARROLL IL-CEDAR IA-CLARK MO-
CLINTON IA-DELAWARE IA-DES MOINES IA-DUBUQUE IA-HANCOCK IL-
HENDERSON IL-HENRY IA-HENRY IL-IOWA IA-JACKSON IA-JEFFERSON IA-
JO DAVIESS IL-JOHNSON IA-JONES IA-KEOKUK IA-LEE IA-LINN IA-LOUISA IA-
MCDONOUGH IL-MERCER IL-MUSCATINE IA-PUTNAM IL-ROCK ISLAND IL-
SCOTLAND MO-SCOTT IA-STEPHENSON IL-VAN BUREN IA-WARREN IL-
WASHINGTON IA-WHITESIDE IL-
500 AM CDT WED APR 20 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST...EAST
CENTRAL...AND SOUTHEAST IOWA...NORTHWEST...NORTH CENTRAL...AND WEST
CENTRAL ILLINOIS...AND NORTHEAST MISSOURI.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL BE POSSIBLE THROUGH THE DAY TODAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL BE FOUND OVER AREAS SOUTH
OF HIGHWAY 20 THIS MORNING...WITH THE BEST COVERAGE OF STORMS
BETWEEN HIGHWAY 30 AND HIGHWAY 34.  THESE STORMS WILL BE CAPABLE OF
BRIEF HEAVY RAIN AND POSSIBLY SMALL HAIL. ANOTHER LARGE AREA OF
THUNDERSTORMS MAY MOVE OUT OF CENTRAL IOWA INTO THE AREA LATER THIS
MORNING AND EARLY THIS AFTERNOON.  IF THESE STORM HOLD TOGETHER...
THEY WILL HAVE THE POTENTIAL TO PRODUCE STRONG WINDS AND POSSIBLY
LARGE HAIL. THE AREA MOST AT RISK FOR THIS SECOND ROUND OF STORMS
WILL BE SOUTHEAST IOWA...WEST CENTRAL ILLINOIS...AND NORTHEAST
MISSOURI. LATE THIS AFTERNOON AND THIS EVENING...SHOWERS AND A FEW
WEAK THUNDERSTORMS WILL BE POSSIBLE OVER AREAS GENERALLY SOUTH OF
HIGHWAY 30.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

RAIN AND SOME EMBEDDED THUNDERSTORMS CAN BE EXPECTED THURSDAY NIGHT
AND FRIDAY MORNING...AS A STRONG LOW PRESSURE SYSTEM AND VERY
STRONG COLD FRONT MOVE THROUGH THE MIDWEST.  MUCH COLDER CONDITIONS
CAN BE EXPECTED FRIDAY AND SATURDAY...WITH FROST POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY AND EARLY TONIGHT...SOUTH OF
HIGHWAY 20.

ERVIN