FXUS63 KGRB 241302 AAA
AFDGRB

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GREEN BAY WI
702 AM CST THU DEC 24 2009

.UPDATE...UPDATED GRIDS/ZFP/WSW/SPS TO ACCOUNT FOR MORE MIXED PCPN
IN THE FCST THIS MORNING. COMBINATION OF WARM LAYER ALOFT AND DRY
SLOT PUNCHING INTO THE AREA HAS RESULTED IN SLEET AND FREEZING RAIN/
FREEZING DRIZZLE ACROSS MOST OF C/EC WI EARLY THIS MORNING. THIS
SHOULD MAKE A PUSH INTO NORTHERN WI AS THE MORNING PROGRESSES.

KIECKBUSCH
&&

.PREV DISCUSSION...ISSUED AT 534 AM CST THU DEC 24 2009...

SHORT TERM...TODAY THROUGH CHRISTMAS DAY...WINTER WEATHER HEADLINES
ARE THE MAIN CONCERN.

GENERALLY SIDED WITH THE SREF WITH REGARD TO THERMAL FIELDS...AS IT
AGAIN OFFERED SOMEWHAT OF A COMPROMISE BETWEEN THE VERY WARM NAM AND
COLDER GFS. IT NOW APPEARS THAT THE WARM LAYER WILL PUSH ALL THE WAY
INTO OUR NW COUNTIES LATE TONIGHT INTO CHRISTMAS MORNING.

SNOW HAS SPREAD INTO NORTHERN WI EARLY THIS MORNING...WITH A MIX
OF SNOW...SLEET AND FREEZING RAIN SOUTH. 06Z RAOB INDICATED THAT
THE MODELS WERE A BIT SLOW WITH THE INITIAL WARM SURGE...AND THIS
HAS BEEN PROVEN BY PCPN TRENDS OVER C/EC WI. SINCE PCPN HAS
OVERSPREAD THE CWA FASTER THAN EARLIER ANTICIPATED...OPTED TO
START ALL OF THE WINTER WX HEADLINES OVER NORTHERN WI THIS
MORNING. THE HEADLINES WILL CONTINUE THROUGH CHRISTMAS DAY ACROSS
MOST OF C/NC/FAR NE WI. WILL END THE WINTER WX ADVISORY ALONG THE
LKSHR THIS AFTERNOON...AND OVER THE FOX VALLEY/BAYSHORE COUNTIES
BY EARLY CHRISTMAS MORNING...AS MIXED PCPN CHANGES OVER TO ALL
RAIN. DID NOT MAKE ANY SERIOUS CHANGES TO PREVIOUS SNOWFALL
AMOUNTS. SOME SIGNIFICANT SLEET ACCUMS ARE EXPECTED IN PARTS OF
CNTRL/NE WI LATE TONIGHT INTO CHRISTMAS MORNING.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.

TIMING THE DEPARTURE OF A MAJOR STORM SYSTEM...CURRENTLY MOVING
INTO
THE REGION...IS THE MAIN CONCERN IN THE LONG TERM. 

MEDIUM RANGE MODELS SHOWED THE SURFACE LOW STARTING TO WEAKEN
OVER
IOWA ON FRIDAY NIGHT. THE SYSTEM WILL REMAIN IN THE REGION AND
CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE COMING
WEEKEND...BEFORE AN UPPER TROUGH AND CYCLONE BEGIN TO MOVE AWAY
FROM THE STATE.

PLENTY OF CLOUDS ASSOCIATED WITH THE SYSTEM...ALONG WITH AT LEAST
A
CHANCE OF SNOW...SHOULD MODERATE TEMPERATURES THROUGH THE
WEEKEND.
CHANCES FOR SNOW SHOULD GRADUALLY DECREASE...BUT LAKE EFFECT IS
POSSIBLE ON THE BACK SIDE OF THE DEPARTING SYSTEM. SO THERE ARE
SMALL AREAS IN NORTH CENTRAL WISCONSIN AND NEAR LAKE MICHIGAN
WITH
POPS SUNDAY NIGHT AND MONDAY. THIS SHOULD COME TO AN END ON
MONDAY
NIGHT AS A SURFACE HIGH REALLY TAKES HOLD AND BRINGS CLEARING
SKIES AND COLDER OVERNIGHT LOWS TO THE AREA.

AN EFFORT WAS MADE TO PRESERVE AS MUCH OF THE PREVIOUS FORECAST
AS
POSSIBLE...MATCH WITH SURROUNDING FORECAST GRIDS AND FOLLOW
LATEST
GUIDANCE. SOME ADJUSTMENTS TO THE FORECAST WERE NECESSARY BECAUSE
OF THIS.

AVIATION...SNOW...MIXED WITH SLEET AND FREEZING RAIN OVER C/EC WI
WILL CONTINUE TODAY. THE PCPN MAY MIX OR CHANGE OVER TO RAIN NEAR
THE LKSHR THIS AFTERNOON. AN EVEN WARMER SURGE OF AIR WILL PUSH
INTO THE RGN LATE TONIGHT...CAUSING MIXED PCPN TO SPREAD NW ACROSS
THE RGN...AND RAIN TO DEVELOP IN THE FOX VALLEY/LKSHR/BAYSHORE
AREAS. EXPECT WIDESPREAD IFR CONDITIONS TODAY AND TONIGHT...ALONG
WITH SOME LLWS.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR WIZ038-039-048-
049-073-074.

WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR WIZ040-050.

WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR WIZ011>013-
018>021-030-031-035>037-045.

WINTER WEATHER ADVISORY UNTIL 6 PM CST FRIDAY FOR WIZ005-010.

&&

$$