FXUS63 KGRB 231134
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
534 AM CST WED DEC 23 2009

.SHORT TERM...TONIGHT THROUGH THURSDAY...WINTER WEATHER HEADLINES
ARE THE MAIN CONCERN.

WITH PART OF THE PREVIOUS WATCH STARTING DURING THE SECOND
PERIOD...NEEDED TO MAKE SOME DECISIONS ON HEADLINES...SO TOOK A
CRACK AT IT. DON'T DOUBT THAT SOME ADJUSTMENTS WILL NEED TO BE
MADE.

LEANED HEAVILY ON SREF THERMAL FIELDS AND QPF. SREF OFFERED A
GOOD COMPROMISE BETWEEN THE VERY WARM NAM...AND THE COOLER GFS/
ECMWF. ALSO...FELT MORE COMFORTABLE BASING THIS FCST OFF THE
AVERAGE OF SEVERAL ENSEMBLE MEMBERS...RATHER THAN PICKING ONE
PARTICULAR MODEL. OVERALL...36-48 QPF TOTALS WERE SOMEWHAT
SIMILAR WITH MOST OF THE MODELS.

OPTED TO CONFINE HEADLINES TO ROUGHLY THE NORTHWEST TWO-THIRDS
OF THE CWA. EXPECT MOST OF THE SIGNIFICANT PCPN TO FALL AS RAIN
OVER THE FOX VALLEY/LKSHR AREAS...WITH MIXED SNOW/SLEET/RAIN
FROM WAUTOMA TO SHAWANO TO CRIVITZ (WINTER WEATHER ADVISORIES)...
AND MAINLY SNOW OVER MOST OF C/NC/FAR NE WI (WINTER STORM
WARNINGS). WITH ALL MODELS SHOWING A MIN IN TOTAL QPF OVER FAR NC
WI...OPTED TO BACK OFF TO JUST A WINTER WX ADVSY FOR VILAS/ONEIDA
COUNTIES.

AFTER A QUIET DAY...PCPN IS EXPECTED TO PICK UP IN CNTRL WI THIS
EVG...AS S/W ENERGY BRUSHES PAST...AND ISENT LIFT INCREASES. WITH
A FEW INCHES OF SNOW AND SOME MINOR SLEET ACCUMS EXPECTED TONIGHT
AND AGAIN ON THURSDAY...FELT IT WAS PRUDENT TO START HEADLINES IN
CNTRL WI TONIGHT...AND JUST CARRY THEM THROUGH CHRISTMAS DAY.
THERE COULD BE SOME LULLS IN PCPN LATER TONIGHT INTO THURSDAY
MORNING...WITH THE HEAVIER SNOW EXPECTED THURSDAY AFTERNOON AND
NIGHT.

FARTHER NORTH...ALTHOUGH SOME LIGHT SNOW WILL AFFECT THE REGION
LATE TONIGHT INTO THURSDAY...DO NOT EXPECT ANY SIGNIFICANT IMPACTS
UNTIL THURSDAY NIGHT...WHEN THE 50-60 KT LLJ CRANKS UP. DELAYED
THE START OF ANY HEADLINES UNTIL THURSDAY EVG FOR NC/NE WI.
THE HEAVIEST SNOW WILL OCCUR THURSDAY NIGHT INTO CHRISTMAS
MORNING.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY. 

A STRONG STORM SYSTEM APPROACHING WISCONSIN IS THE MAIN CONCERN
DURING THIS PART OF THE FORECAST...ESPECIALLY SINCE IT WILL
GREATLY IMPACT A MAJOR HOLIDAY. 850MB WINDS IN EXCESS OF 50 KNOTS
IN ADVANCE OF THE SYSTEM WILL BRING PLENTY OF MOISTURE AND WARM
AIR INTO THE AREA. THE SOUTHEAST HALF OF THE FORECAST AREA SHOULD
HAVE THE HIGHEST QPF...BUT HOW MUCH OF THAT FALLS AS SNOW VS. RAIN
OR MIXED PRECIPITATION IS A MAJOR HEADACHE.

HAVE ATTEMPTED TO FOLLOW THE 21Z SREF MORE CLOSELY THAN THE OTHER
MODELS. IT BROUGHT ENOUGH WARM AIR INTO THE FOX VALLEY AND LAKESHORE
AREAS TO KEEP PRECIPITATION IN THE FORM OF RAIN THROUGHOUT THE
PERIOD OF HEAVIEST PRECIPITATION. SO ADVISORIES OR WARNINGS DO NOT
APPEAR WARRANTED FOR THAT PART OF THE FORECAST AREA. THE CHANGE IN
PRECIPITATION STATE FROM RAIN TO SNOW IS LIKELY TO BE RATHER
ABRUPT. SO HAVE MAINLY MENTIONED SNOW IN A SOUTHWEST TO NORTHEAST
STRIP FARTHER TO THE NORTHWEST OF THE RAIN...WITH A CHANCE OF
FREEZING RAIN OR SLEET AND LOWER SNOW TO LIQUID RATIOS. THIS AREA
WILL STILL PROBABLY END UP WITH THE GREATEST SNOWFALL TOTALS OUT
OF THE SYSTEM. EVEN IF IT DOES NOT MEET SNOWFALL CRITERIA THE
POTENTIAL MIX OR FREEZING PRECIPITATION TIPS THE BALANCE IN FAVOR
OF GOING WITH A WARNING FOR A SWATH FROM CENTRAL INTO NORTHEAST
WISCONSIN...BUFFERED BY ADVISORIES TO THE SOUTHEAST AND NORTHWEST.
THE SURFACE SYSTEM WILL FILL AS IT SLOWLY MAKES ITS WAY OUT OF THE
STATE EARLY NEXT WEEK. COLD AIR WILL MAKE ITS WAY INTO THE
EASTERN PART OF THE AREA AS IT WRAPS AROUND THE SURFACE LOW. BUT
BY THAT TIME QPF VALUES ARE EXPECTED TO BE MUCH SMALLER AND ANY
SNOWFALL WILL BE TOO LITTLE TO REACH EVEN ADVISORY CRITERIA IN THE EAST.

MAKE SOME CHANGES TO TEMPERATURES...MORE TOWARD THE HPC GUIDANCE
BUT THEY WERE NOTHING MAJOR. ONCE THE SYSTEM PASSES EAST OF THE
STATE COLDER WEATHER IS IN STORE.
&&

.AVIATION...PATCHY MVFR CIGS SHOULD CONTINUE TODAY...WITH CONTINUED
EAST FLOW OFF LK MICH. EXPECT MORE WIDESPREAD LOW CLOUDS TO DEVELOP
AS SNOW ARRIVES IN CNTRL WI THIS EVG...AND GRADUALLY SPREADS NORTH.
COULD SEE SOME IFR CONDITIONS...ESP IN CNTRL WI OVERNIGHT. LLWS IS
ALSO EXPECTED TO DEVELOP TONIGHT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST 
FRIDAY FOR WIZ037-045.

WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY 
FOR WIZ005-010-020-031-073-074.

WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST FRIDAY 
FOR WIZ030-035-036.

WINTER STORM WARNING FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR 
WIZ011>013-018-019-021.

&&

$$
TSK/MG