FXUS63 KLOT 280853
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
253 AM CST SAT NOV 28 2009

.DISCUSSION...
238 AM CST

HIGH PRESSURE RIDGING OFF TO OUR EAST OPENS UP THE GATES TO WARM AIR 
ADVECTION INTO THE MIDWEST. UPR WEST TO SW FLOW IS PERMITTING 850 
TEMPS TO PUSH UP TO 10C TO 12C TODAY...WARMING SFC TEMPS TO THE MID 
50S. AMPLE SUNSHINE AND LIGHT WINDS WILL ASSIST. ANOTHER TERRIFIC 
SHOPPING DAY IS THUS IN STORE...CONFLICTING WITH THE NORMAL LATE
NOVEMBER HIGHS NEAR 40.

THIS WARM SPELL IS OUT AHEAD OF AN APPROACHING COLD FRONT THAT 
STRETCHES FROM NW MINNESOTA TO NORTHWEST KANSAS EARLY THIS MORNING. 
THIS FRONT IS PROGGED TO MOVE SOUTHEAST INTO NRN IL EARLY SUNDAY. 
INCREASING WAA CLOUDINESS WILL PRECEDE THIS FRONTAL APPROACH LATE 
TONIGHT. HOWEVER RAIN CHANCES HAVE BETTER PROSPECTS NORTH AND SOUTH 
OF THE FORECAST AREA. TIMING OF A DEEPENING UPPER TROF PHASING 
WITH THIS SFC FEATURE WILL DETERMINE WHEN AND WHERE RAINS BECOME 
MORE ACTIVE ALONG THIS SFC BOUNDARY. PRESENT TRENDS INDICATE THAT 
THE COLD FRONT WILL BE THROUGH THE FORECAST AREA BEFORE BLOWING UP 
ACROSS THE OHIO VALLEY INTO HEAVIER AND MORE WIDESPREAD SHOWERS. 
PROBABILITIES HOWEVER WOULD RELY ON THE FACT THAT THE LONGER IT
TAKES FOR THE FRONT TO MOVE THROUGH AN AREA ON SUNDAY...THE HIER IS 
THE LIKELIHOOD OF SUCCUMBING TO A HIER CHANCE OF RAIN. FOR NOW ONLY 
A SLIGHT CHANCE EXISTS ACROSS THE AREA WITH HIER POPS IN THE 
SOUTHEAST PORTION OF THE FORECAST AREA. IF ANY RAIN SHOULD 
DEVELOP...IT SHOULD BE SHORTLIVED AND ONLY A FEW HUNDREDTHS AT BEST. 
THUS THIS SHOULD NOT BE A DETERRENT FROM CONTINUING THE POST 
THANKSGIVING SHOPPING MARATHON INTO SUNDAY.

SFC HIGH PRESSURE BUILDING ACROSS THE PLAINS AND INTO THE MIDWEST 
LATE SUNDAY AND MONDAY WILL NOT OFFER MUCH CLEARING UNTIL THE MAIN 
UPPER TROF SWINGS THRU THE LAKES REGION LATE ON MONDAY. SHORTLY 
AFTER THAT ANOTHER SFC LOW WILL WORK EAST OUT OF MANITOBA TUESDAY
AND ACROSS SRN ONTARIO TUES NIGHT.

MODELS VARY AFTER THIS POINT ON TIMING OF ANOTHER UPR TROF DROPPING 
SE THRU THE MIDWEST. PRESENTLY LEANING TO A SOLUTION WITH A WARMUP 
WEDNESDAY AND A COOLING UPR TROF PASSAGE LATE THURSDAY. OTHERS 
SUGGEST A CHILLING COLD FRONTAL PASSAGE WEDNESDAY...COMPOUNDING CAA 
EVEN FURTHER WITH THE UPR TROF PASSAGE THURSDAY.

TO CURTAIL THE FLIP FLOPPING POSSIBILITIES...WILL LEAVE THE EXTENDED
PORTION OF THE FORECAST AS IS FROM MIDWEEK ON.

RLB

&&

.AVIATION...
1045 PM CST

0600 UTC TAFS...WX NIL TIL VERY LATE IN VALID PD OF TAFORS AND
ONLY ITEM OF INTEREST IS EXACT TIMING OF WSHFT OF LIGHT SFC WINDS FM
SW TO NW.

SFC RIDGE AXIS CURRENTLY EXTENDS ACROSS THE OH VALLEY NNW OVER
NORTHERN LAKE MI AND EASTERN LK SUPERIOR. WITH RIDGE TO E...WEAK
RATHER ILL DEFINED LO TO THE W AND A WARM FRONT ACROSS SW IA...NE MO
AND FAR SOUTHERN IL PREVAILING SFC FLO AT TERMINALS TO BE FM THE
SSE OVERNIGHT INTO SAT MORNING. LIGHT WIND TO BECOME SOUTHERLY DURING
THE MORNING AND THEN FROM THE SW IN THE AFTERNOON AS RIDGE DRIFTS
TO THE CENTRAL LAKES AND UPPER OH VALLEY AND THE LO PRES TROF
APPROACHES EVER SO SLOWLY FM THE NW.

FOR OVERNIGHT SAT NIGHT...SOME TIMING DIFFERENCES AS TO WHEN
TROF/COLD FRONT MOVES ACROSS N CENTRAL AND NE IL. WILL GO WILL SLOWER
PACE AS CONSENSUS OF MODELS AND TREND OF LIGHTLY SLOWER MOVEMENT
BY LATEST ETA RUN...EXCELLENT CONTINUITY IN GFS BETWEEN CURRENT AND
PREVIOUS RUNS...AS WELL AS SUPPORT FROM 12Z GFS ENSEMBLE MEAN AND
12Z ECMWF. 21Z SREF DID LEAN MORE TOWARD A BIT EARLIER PASSAGE ALA
LATEST ETA. 

TRS

&&

.MARINE...
127 PM CST

A RIDGE OF HIGH PRESSURE EXTENDS FROM THE EASTERN GULF COAST
NORTHWARD ACROSS THE EASTERN GREAT LAKES REGION AND ONTARIO. THE
RIDGE WILL GRADUALLY SHIFT EAST TO THE ATLANTIC SEABOARD BY
SATURDAY EVENING. MEANWHILE...A BROAD TROUGH OF LOW PRESSURE OVER
THE PLAINS WILL CONSOLIDATE INTO A WEAK LOW OVER SOUTHERN
WISCONSIN SATURDAY NIGHT. THIS LOW WILL MOVE ACROSS CENTRAL LAKE
MICHIGAN SUNDAY MORNING. AS THE LOW CONTINUES EASTWARD...A LARGE
AREA OF HIGH PRESSURE OVER THE ROCKIES WILL EXPAND ACROSS THE
SOUTHERN PLAINS TO THE LOWER OHIO VALLEY. BY TUESDAY THIS HIGH
WILL EXTEND FROM THE CAROLINAS TO TEXAS.

&&

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

$$