FXUS63 KGRB 251033
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
433 AM CST WED NOV 25 2009

.SHORT TERM...TODAY THROUGH THANKSGIVING DAY. UPPER LOW LIFTING
SLOWLY NORTHEAST FROM LAKE MICHIGAN EARLY TODAY WHILE ANOTHER
UPPER LOW DIVES SOUTHEAST FROM THE EASTERN DAKOTAS TO NORTHERN
ILLINOIS. LIGHT TO MODERATE RAIN WILL CONTINUE THROUGH MID MORNING
OVER THE EASTERN HALF OF THE FORECAST AREA THEN IT SHOULD DIMINISH
TO SCATTERED LIGHT RAIN OR DRIZZLE AS LOW LEVEL WARM ADVECTION AND
CONVERGENCE COMES TO AN END. RAIN WILL PICK UP AGAIN LATE IN THE
DAY AND TONIGHT IN CENTRAL AND EAST CENTRAL WISCONSIN AS LEFT EXIT
REGION OF UPPER JET MOVES ACROSS. 

PRECIPITATION TYPE ISSUES SHOULD BE MINIMAL THROUGH THE DAYLIGHT
HOURS THEN BEGIN TO GET A BIT MORE CHALLENGING TONIGHT. 850MB
TEMPERATURES COOL TO -2C TO -4C IN THE CENTRAL COUNTIES TONIGHT
WHICH WOULD USUALLY BE COLD ENOUGH TO GET SNOW AT THIS TIME OF
YEAR. BUT NOVEMBER HAS BEEN UNUSUALLY WARM AND THE GROUND QUITE
WARM AS WELL. SO EXPECT THAT THE RAIN WILL CHANGE TO SNOW TONIGHT
BUT NOT ACCUMULATE TO ANY GREAT EXTENT DUE TO MILD BOUNDARY LAYER
TEMPERATURES AND WARM GROUND. THERE MAY BE AN INCH OR SO ON GRASSY
SURFACES.

IN ADDITION TO PRECIPITATION TYPES ISSUES TONIGHT...THERE IS ALSO
A QUESTION OF THE NORTHWARD EXTENT OF THE SIGNIFICANT PRECIPITATION.
THE AXIS OF BEST PRECIPITATION HAS SHIFTED SOUTHWARD IN THE LAST
FEW MODEL RUNS SO THAT WILL LIMIT CHANCE OF ACCUMULATING SNOW IF
THAT TREND CONTINUES. WILL MENTION THE CHANCE OF SOME SMALL SNOW
ACCUMULATIONS ON THE GRASS IN THE HAZARDOUS WEATHER OUTLOOKS.
SNOW/RAIN SHOWERS SHOULD END EARLY THANKSGIVING DAY THEN IT WILL
BE BLUSTERY AND COLDER. LAKE EFFECT SNOW SHOWERS IN VILAS COUNTY
COULD PRODUCE AN INCH NEAR THE MICHIGAN BORDER.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY. 

THE MAIN CONCERN DURING THIS PART OF THE FORECAST IS AN
APPROACHING SYSTEM THAT IS EXPECTED TO IMPACT THE AREA DURING THE
LATTER PART OF THE WEEKEND.

MODELS WERE IN GOOD AGREEMENT IN REMOVING PRECIPITATION FROM THE
FORECAST AREA BY LATE THIS WEEK. THERE IS ONLY A SLIGHT CHANCE OF SNOW
SHOWERS IN NORTHERN DOOR COUNTY AS THE SURFACE AND UPPER LEVEL
SYSTEMS DEPART. WINDS SHOULD NOT BE FROM A FAVORABLE DIRECTION FOR
LAKE EFFECT IN THE NORTH-CENTRAL PART OF THE STATE. SURFACE HIGH
PRESSURE AND A RELATIVELY LOW AMPLITUDE UPPER LEVEL RIDGE SHOULD
KEEP THE AREA DRY FOR MOST OF THE WEEKEND.

MODELS DIFFERED IN THEIR HANDLING OF A SURFACE LOW EXPECTED TO
PASS THROUGH THE REGION DURING THE LATTER HALF OF THE
WEEKEND...AHEAD OF AN APPROACHING UPPER TROUGH. 00Z GFS HAD THE
MAIN SURFACE LOW PASSING SOUTH OF THE STATE...WHILE THE 00Z ECMWF
HAD A STRONGER LOW FORECAST TO MOVE THROUGH WISCONSIN. HPC
MANUAL GUIDANCE PRODUCTS FROM MIDDAY TUESDAY HAD THE LOW FARTHER
SOUTH THAN THE EC SOLUTION...AND MEDIUM RANGE COMPARISON DID NOT
SEEM TO INDICATE A CONSENSUS...SO HAVE GONE WITH A SOLUTION
CLOSER TO THE 00Z GFS...HIGHER POPS TO THE SOUTH AND LOWER TO THE
NORTH SUNDAY AND SUNDAY NIGHT.

ONLY MINOR CHANGES WERE MADE TO TEMPERATURES.
&&

.AVIATION...IFR CIGS AND/OR VSBYS WILL GRADUALLY INCREASE TO MVFR
IN MOST PLACES THIS EVENING AND TO VFR THANKSGIVING DAY. SOME WET
SNOW POSSIBLE OVERNIGHT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$
RDM/MG