Lake County SKYWARN

NWS Area Forecast Discussion

FORMAT:

Decoded

Original

FXUS63 KLOT 180910
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 AM CDT FRI APR 18 2008

.DISCUSSION...
407 AM CDT

THE LOW OVER MISSOURI WILL MOVE SLOWLY INTO EASTERN IOWA BY MIDNIGHT
SATURDAY MORNING. PRECIPITATION WILL BE SLOW MOVING INTO THE CWA
OF NORTH CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST
INDIANA. WILL LEAVE A CHANCE OF RAIN FOR THIS AFTERNOON USING
PROBABILITY OF AROUND 30 PERCENT. WILL FORECAST OCCASIONAL RAIN
FOR TONIGHT FOR MOST OF THE CWA EXCEPT FOR THE FAR EAST. WE EXPECT
MOST OF THE RAIN WILL BE OVER THE WHOLE CWA BY SATURDAY MORNING.
THE GFS MODEL WAS USED BEYOND 24 HOURS. THE LOCALLY RUN WRF ARW
AND THE SHORT RANGE ENSEMBLE FORECAST WERE VERY CLOSE IN THE LOW
FORECAST FOR FRIDAY EVENING. THE LOW CENTER WAS 100 MILES NORTH IN
EASTERN IOWA THAN THE SREF. BUT OUR LOCAL MODEL IS JUST ONE
SOLUTION OF THE FORECAST EQUATIONS...NOT A TEST OF A SET OF
SOLUTIONS AND OUR DOMAINS AND BOUNDARY ADJUSTMENTS ARE DIFFERENT.
THE FORECAST TEMPERATURE FIELDS WERE CLOSE ENOUGH SO WILL USE A
BLEND OF THE TWO FOR THE FORECAST UP TO 24 HOURS.

MOST OF THE RAIN WILL OCCUR ON SATURDAY. FOR THE TWO DAYS THE
STORM TOTAL PRECIPITATION IS FORECAST WILL RANGE FROM .57 INCHES
IN WESTERN OGLE AND LEE COUNTIES TO .25 INCHES IN VALPARAISO AND
FOWLER INDIANA. THE LONG MERIDIONAL TROUGH OVER THE PLAINS STATES
WILL MOVE EAST INTO THE OHIO VALLEY WHERE THE 500 MB LOW IS
EXPECTED TO BECOME CLOSED OVER SOUTHERN OHIO AND KENTUCKY. WE
EXPECT THIS TO OCCUR SUNDAY. THE LARGEST HEIGHT FALLS WERE OVER
TEXAS AT 00 UTC FRIDAY. LARGE WIND SHEARS FROM 850 TO 700 MB WERE
NOTED OVER TEXAS AND OKLAHOMA. THIS SHOWS THE TROUGH WILL BECOME
DEEPER AS IT BEGINS TO TILT TO THE EAST. THE GFS MODEL SHOWS THIS.
THE HIGH TEMPERATURES WILL BE IN THE 60S TODAY AND IN THE UPPER
50S SATURDAY. THEN BACK INTO THE MIDDLE 60S. ANOTHER LOW WILL MOVE
INTO THE GREAT PLAINS AND THE WIND OVER ILLINOIS IS FORECAST TO
BECOME SOUTHEAST TO SOUTH BY MONDAY. WE WILL FORECAST THE HIGH IN
THE 70S FOR MONDAY.

&&

.AVIATION...
104 AM CDT

RE 06Z TAFORS...MID/UPPER LOW CONTINUES TO CUT OFF OVER THE CENTRAL
PLAINS RESULTING IN BACKING FLOW ACROSS THE MID MS VALLEY NE INTO
THE WESTERN GREAT LAKES. WEAK CIRCULATION THAT WAS MOVING UP THE
SURFACE BOUNDARY OVER THE QUAD CITIES DURING THE EARLY AND MID
EVENING HAS BECOME INDISCERNIBLE. MAIN SURFACE LOW ON THE KS/MO
BORDER FORECAST TO MOVE NNE TO NW MO BY 12Z WHICH SEEMS QUITE
REASONABLE GIVEN BACKING FLOW SURFACE AND ALOFT AND SURFACE
PRESSURE FALL CENTER CURRENTLY OVER CENTRAL IA. WITH MOVEMENT OF
THE SURFACE LOW AND 30-40KT S-SSW LOW LEVEL WINDS PER PROFILERS
AND VAD WINDS THE LAKE ENHANCED BOUNDARY ACROSS FAR NE IL
WILL CONTINUE TO WASH OUT OVERNIGHT WITH WIND AT MDW AND ORD
VEERING TO S-SSE DURING THE REST OF THE OVERNIGHT.

MODELS MOVE MID/UPPER LOW TO WESTERN MO BY 00Z SAT WITH ASSOCIATED
SURFACE LOW REACHING SE OR E CENTRAL IA BY THAT TIME. EXPECT MAIN
RIBBON OF RAIN TO CREEP BACK INTO THE RFD AREA BY MID AFTERNOON
BUT ONLY VERY GRADUALLY WORK ITS WAY E TO THE CHI AREA BY EARLY
EVENING. COULD BE A TS OR TWO INTO NORTHERN IL WITH THE SHOWERS
BUT VARIOUS INSTABILITY VALUES NOT THAT IMPRESSIVE SO NOT A HIGH
ENOUGH THREAT TO MENTION IN CURRENT SET OF TAFORS.

TRS

&&

.MARINE...
208 AM CDT

A FRONTAL BOUNDARY WILL REMAIN DRAPED ACROSS CENTRAL LAKE MICHIGAN
WHILE LOW PRESSURE MOVES NE ACROSS MO AND INTO IA TODAY...THEN E
INTO NORTHERN IL TONIGHT. ONLY MODERATE TO FRESH BREEZES EXPECTED
AS THE LOW IS NOT PARTICULARLY DEEP AND THEN CENTER OF HI PRESSURE
IS WELL REMOVED OVER NORTHERN QUEBEC. AS THE LOW MOVES ACROSS OR
JUST SOUTH OF THE FAR SOUTHERN GREAT LAKES OVERNIGHT INTO SUN
PREVAILING WINDS BECOME GENTLE.

TRS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.

&&

$$

| contact | disclaimer |