Damaging Wind in Illinois, July 25, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
913 PM CDT MON JULY 25 2005

.DISCUSSION...LATEST SURFACE ANALYSIS HAD LOW PRESSURE CENTERED JUST
SOUTH OF LA CROSSE WISCONSIN. A WARM FRONT EXTENDED EAST FROM THE
LOW OVER THE UPPER GREAT LAKES AND A COLD FRONT EXTENDED SOUTHWEST
FROM THE LOW TO ANOTHER LOW OVER KANSAS. ALOFT...BROAD SOUTHWESTERLY
FLOW WAS EVIDENT FROM THE SOUTHERN PLAINS INTO THE WESTERN GREAT
LAKES. A FEW IMPULSES WERE APPROACHING FROM THE PLAINS...WITH THE
MOST NOTABLE WAVE MOVING INTO THE UPPER MIDWEST.

CONVECTION HAS REALLY ERUPTED THIS EVENING ALONG THE WARM AND COLD
FRONTS AND THE PRIMARY CONCERN OVERNIGHT IS HOW MUCH (IF ANY) OF
THIS CONVECTION WILL REACH US BY MORNING. THE AIRMASS OVERHEAD IS
RELATIVELY MOIST (AND UNSTABLE)...THOUGH A TONGUE OF DRY AIR IS
NOTED IN THE SURFACE ANALYSIS AND WATER VAPOR IMAGERY FROM THE
SOUTHERN PLAINS INTO NORTHWEST ILLINOIS. THIS DRY AIR EXTENDS WEST
TO A POINT JUST AHEAD OF THE CONVECTION.

THE NORTHERN PORTION OF THE COLD FRONT SHOULD BE MOST PROGRESSIVE...
WITH THE BEST UPPER WAVE AND LOW LEVEL JET DYNAMICS NOSING INTO THIS
AREA. THE CONVECTION FURTHER SOUTH SHOULD TEND TO WEAKEN GIVEN THE
LESSER DYNAMICS AND LOSS OF DIURNAL HEATING. THE FRONT IS ONLY
EXPECTED TO APPROACH NORTHWEST ILLINOIS BY 12Z TUESDAY...SO FEEL
NORTHEAST FORECAST AREA SHOULD STAY DRY OVERNIGHT.

SEVERAL TWEAKS ARE NEEDED TO GOING GRID/ZONES PER LATEST/EXPECTED
TRENDS. WILL ALSO ALLOW HEAT HEADLINES TO EXPIRE AT 11 PM...THOUGH
LATEST INDICATIONS ARE THAT AN ADVISORY MAY BE NEEDED AGAIN ALONG
AND SOUTH OF I-70 FOR TUESDAY.

&&

.PREV DISCUSSION...TIMING OF COLD FRONT ACROSS CENTRAL ILLINOIS
TOMORROW ALONG WITH RAIN CHANCES WILL BE THE PRIMARY FORECAST
CHALLENGE IN THE NEAR TERM. SOME MODEL DIFFERENCES SEEN WITH THE QPF
FIELDS ALONG AND NORTH OF THE COLD FRONT LATE TUESDAY INTO EARLY
WEDNESDAY. FEEL THE NAM HAS THE RIGHT IDEA WITH THE FRONTAL POSITION
AND QPF FIELDS ALONG IT SO WILL TEND TO SIDE WITH IT THRU WEDNESDAY.
FEEL THE GFS HAS SUFFERING FROM FEEDBACK PROBLEMS RESULTING IN QUITE
A BIT OF MORE QPF AND STRONGER SFC WAVE ALONG THE BOUNDARY. FURTHER
OUT...AMPLIFYING TROF ACRS THE GREAT LAKES SHOULD RESULT IN NWLY
FLOW PATTERN OVER OUR AREA FOR THE SECOND HALF OF THE WEEK WHICH
SHOULD BRING TEMPERATURES BACK TO NEAR NORMAL.

SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...
FIRST THINGS FIRST...WILL EXTEND OUR CURRENT HEAT RELATED ADVISORIES
AND WARNINGS UNTIL 11 PM THIS EVENING. TEMPS THIS HOUR ABOUT THE SAME
AS YSTDY AND WILL NOT SEE ANY SIGNIFICANT DROP OFF IN HEAT INDEX
VALUES UNTIL A FEW HOURS AFTER SUNSET. FRONTAL BOUNDARY TO OUR NORTH
IS STARTING TO EDGE BACK NORTH EARLY THIS AFTERNOON AS LOW PRESSURE
PUSHES EAST INTO NRN IOWA. LATEST WATER VAPOR LOOP INDICATING PLUME
OF MOISTURE STREAMING NWD INTO OUR WRN COUNTIES THIS AFTERNOON
HELPING TO SPARK OFF SOME ISOLATED CONVECTION. WL CARRY ISOLATED
WORDING THIS EVENING OVER ALL BUT OUR SOUTHEAST COUNTIES AND THEN
LOW CHANCE POPS OVER THE FAR NORTH FOR LATE TNT AS THE SFC WAVE OVR
NRN IA MOVES TOWARDS THE MISSISSIPPI RIVER AFTR MIDNIGHT. BEST LOW
LEVEL CONVERGENCE/ THETA-E ADVECTION/MOISTURE TRANSPORT AND AXIS OF
LOW LVL JET SUGGEST MOST FAVORABLE LOCATION FOR WDSPRD CONVECTION
SHOULD REMAIN NORTH OF THE FCST AREA THROUGH MIDNIGHT. CONVECTION
CHANCES INCREASE FROM NW TO SOUTHEAST DURING THE DAY ON TUESDAY AS
THE FRONTAL BOUNDARY SHIFTS ACRS THE FCST AREA. 0-6KM SHEAR
INDICATING FROM 20-30 KTS BY AFTN ACRS CNTRL IL WITH DECENT CAPE
VALUES SUGGESTING BEST THREAT WITH ANY STORMS THAT ORGANIZE MAY POSE
A THREAT FOR STRONG STRAIGHT LINE WINDS. WITH THE EXPECTED INCREASE
IN CLOUD COVER TUESDAY AND TIMING OF THE FRONT THRU CNTRL IL DURING
THE DAY...TEMPERATURES WILL BE COOLER THAN THE PAST FEW
DAYS...ESPECIALLY ACRS THE NW HALF OF THE FCST AREA.

RAIN CHANCES WILL BE HIGHEST ALONG AND SOUTHEAST OF INTERSTATE 72 TUE
NIGHT AS THE FRONTAL BOUNDARY EDGES SLOWLY SE.  RAIN CHANCES TO
REMAIN OVER THE SOUTHEAST THRU WEDNESDAY AFTERNOON AS THE FRONT
BECOMES MORE PARALLEL TO THE UPPER FLOW. HOWEVER...THE UPPER TROF
SHOULD CONTINUE TO AMPLIFY ACRS THE LAKES REGION RESULTING IN OUR
FLOW BECOMING MORE NWLY WHICH SHOULD HELP PUSH THE FRONT FURTHER
SOUTH TAKING ALL THE RAIN WITH IT. AFTER THAT...HIGH PRESSURE SHOULD
BUILD INTO THE MIDWEST BRINGING COOLER AND MUCH LESS HUMID AIR INTO
THE MID MISSISSIPPI VALLEY.

LONG TERM...FRIDAY THROUGH MONDAY...
PLEASANT WEATHER CONDITIONS TO HOLD ACRS CNTRL IL THROUGH THE
EXTENDED PERIOD AS THE UPPER FLOW REMAINS NWLY. SVL WEAK SHORTWAVES
EXPCTD TO DROP SOUTHEAST INTO THE LAKES REGION DURING THE PERIOD BUT
MOISTURE WILL BE LIMITED AT BEST AHEAD OF THESE FEATURES...AS A
RESULT WILL KEEP THE EXTENDED DRY WITH NEAR NORMAL TEMPERATURES.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
IL...NONE.

BAK/SMITH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
1039 AM CDT MON JUL 25 2005

ILZ042>057-061>063-066>068-071>073-261100-
CASS-CHAMPAIGN-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND-
DE WITT-DOUGLAS-EDGAR-EFFINGHAM-JASPER-LAWRENCE-LOGAN-MACON-MENARD-
MORGAN-MOULTRIE-PIATT-RICHLAND-SANGAMON-SCOTT-SHELBY-VERMILION-
INCLUDING THE CITIES OF...CHAMPAIGN...DANVILLE...DECATUR...
EFFINGHAM...FLORA...JACKSONVILLE...LAWRENCEVILLE...LINCOLN...
MATTOON...SHELBYVILLE...SPRINGFIELD AND TAYLORVILLE
1039 AM CDT MON JUL 25 2005

...EXCESSIVE HEAT WARNING CONTINUES UNTIL 7 PM THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND SOUTHEAST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT...

HIGH TEMPERATURES AROUND 100 DEGREES WILL COMBINE WITH A VERY MOIST
TROPICAL AIRMASS TO PRODUCE HEAT INDEX VALUES OF 105 TO 110 DEGREES
THIS AFTERNOON.

OUTFLOW ASSOCIATED WITH A THUNDERSTORM COMPLEX OVER THE UPPER MIDWEST
IN THE OVERNIGHT HOURS WILL MOVE THROUGH THE AREA IN THE EARLY
AFTERNOON HOURS...PRODUCING SCATTERED THUNDERSTORMS.  WITH VERY DRY
AIR ALOFT...THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE HAIL AND
DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

A COLD FRONT WILL MOVE INTO THE AREA TUESDAY...BREAKING THE HEAT AND
BRINGING SCATTERED THUNDERSTORMS. SOME OF THE STORMS MAY BE SEVERE
TUESDAY AFTERNOON AND EVENING. THE MAIN WEATHER THREATS WILL BE
STRONG WINDS AND POTENTIALLY HEAVY RAINFALL. THE CHANCE FOR
THUNDERSTORMS WILL LAST INTO THE FIRST PART OF WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

ILZ027>031-036>038-040-041-261100-
FULTON-KNOX-MARSHALL-MASON-MCLEAN-PEORIA-SCHUYLER-STARK-TAZEWELL-
WOODFORD-
INCLUDING THE CITIES OF...BLOOMINGTON...GALESBURG...HAVANA AND PEORIA
1039 AM CDT MON JUL 25 2005

...HEAT ADVISORY IN EFFECT UNTIL 7 PM THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH-CENTRAL ILLINOIS.

.DAY ONE...TODAY AND TONIGHT...

HIGH TEMPERATURES NEAR 100 DEGREES WILL COMBINE WITH A VERY MOIST
TROPICAL AIRMASS TO PRODUCE HEAT INDEX VALUES OF 105 TO 110 DEGREES
THIS AFTERNOON.

OUTFLOW ASSOCIATED WITH A THUNDERSTORM COMPLEX OVER THE UPPER MIDWEST
IN THE OVERNIGHT HOURS WILL MOVE THROUGH THE AREA THIS MORNING AND
INTO THE EARLY AFTERNOON HOURS...PRODUCING SCATTERED THUNDERSTORMS.
WITH VERY DRY AIR ALOFT...THE MAIN THREAT FROM THESE THUNDERSTORMS
WILL BE LARGE HAIL AND DAMAGING WINDS. THUNDERSTORMS MAY CONTINUE
INTO THE EVENING HOURS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

A COLD FRONT WILL CONTINUE THROUGH THE AREA TUESDAY...BREAKING THE
HEAT AND BRINGING MORE THUNDERSTORMS. SOME OF THE STORMS MAY BE
SEVERE TUESDAY AFTERNOON AND EVENING. THE MAIN WEATHER THREATS WILL
BE STRONG WINDS AND POTENTIALLY HEAVY RAINFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TONIGHT.

&&
THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC AND CLIMATE
INFORMATION...IS AVAILABLE ON THE WEB AT:

HTTP://WWW.WEATHER.GOV/LINCOLN. THIS ADDRESS IS ALL IN LOWER CASE.

HJS