FXUS63 KGRB 040935
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
335 AM CST FRI DEC 4 2009

.SHORT TERM...TODAY AND SATURDAY

RATHER POTENT UPPER WAVE THAT BROUGHT LIGHT SNOW SHOWER/FLURRY
ACTIVITY THIS EVENING IN OUR CWA AND MEASURABLE SNOWS TO SOUTHERN
WI...NOW EXITING THROUGH LOWER MI. ISOLATED LIGHTNING SEEN EARLIER
WITH SYSTEM.

SORT OF IN BETWEEN WAVES FOR DAY PERIOD TODAY WITH NEXT SYSTEM
DROPPING SOUTH THROUGH LAKE WINNIPEG REGION ATTM. THOUGH WEAKER
PIECES OF ENERGY SEEN ROTATING THROUGH TROF POSITION OVER THE
WESTERN LAKES WITH PLENTY OF FLURRY ACTIVITY CONTINUING OVER WI.
HAVE ADDED SOME SMALL POPS MAINLY NORTH AND WEST FOR TONIGHT AS
NEXT WAVE/CLOSED LOW DROPS INTO LAKE SUPERIOR REGION. STAYED WITH
DRY FORECAST FOR SATURDAY AS MOISTURE DRIES OUT AND FLOW BECOMES
MORE ZONAL OVER THE STATE.

NO MAJOR CHANGES TO CURRENT TEMPERATURES TRENDS.

.LONG TERM...SAT NGT THRU NXT THU. MDLS CONT TO ADVERTISE A MAJOR
PATN CHG WITH AN UPR LVL RDG BUILDING TOWARD ALASKA IN RESPONSE TO
A VERY STG SFC LOW OVR THE PACIFIC. A STG MID-LVL FLOW TO EXTEND
FROM THE CNTRL PACIFIC INTO THE WRN CONUS TYPICAL OF AN EL NINO
PATN. A STG UPR JET IS FCST TO DIVE SWD ON THE ERN SIDE OF THE UPR
RDG AND CARVE OUT A DEEP UPR TROF OVR THE WRN CONUS EARLY NXT
WEEK. IT IS FROM THIS UPR TROF THAT TWO DISTINCT SYSTEMS WL HEAD
EAST ACROSS THE CONUS WITH THE SECOND SYSTEM POSSIBLY BRINGING THE
FIRST MAJOR STORM TO THE GREAT LKS AT MID-WEEK.

A WEAK CDFNT PUSHES THRU THE NW HALF OF WI SAT NGT WITH THE MAIN
RESULT BEING A WND SHFT TO THE NORTH. FORCING OVERALL IS
RELATIVELY WEAK AND LIFT IS WEAK AS WELL...THUS HAVE ONLY
RELEGATED A FEW FLURRIES ALONG THE FNTL BNDRY OVR N-CNTRL WI.
PLENTY OF CLDS AROUND WL PREVENT TEMPS FROM FALLING TOO FAR WITH
READINGS SIMILAR TO FRI NGT (LWR TEENS NORTH/LWR 20S NEAR LK MI).

NAGGING QSTNS LINGER AS TO HOW FAR THIS CDFNT CAN SAG BEFORE IT
BECOMES INFLUENCED BY A LRG HI PRES OVR THE MID-ATLANTIC STATES.
THE NAM IS SLOWEST WITH THE BNDRY ONLY REACHING THE SE CORNER OF
THE FCST AREA BY 00Z MON. CONVERSELY...THE CANADIAN SENDS THE FNT
DOWN TOWARD THE CHICAGO METRO AREA. HAVE SETTLED ON AN ECMWF/GFS/
UKMET DIPLOMATIC APPROACH BY TAKING THE FNT INTO SE WI BY LATE
SUNDAY. ENUF OF A NORTHERLY COMPONENT TO THE WNDS TO PREVENT ANY
LK EFFECT SNOW SHWRS FROM EITHER LK SUPERIOR OR LK MI. THERE COULD
BE SOME SPOTTY FLURRIES AROUND AS COOLER AIR ENTERS THE RGN AND
SHRTWVS ALOFT PASS NEARBY. HAVE LOWERED MAX TEMPS A COUPLE OF DEGS
FROM THE PREV FCST.

FOCUS SHIFTS TOWARD THE CNTRL PLAINS WHERE A SHRTWV TROF IS FCST
TO MOV NE INTO THE MIDWEST SUNDAY NGT. A WEAK SFC LOW WL MOV ALONG
THE NOW-STALLED FNTL BNDRY AND PUSH INTO NRN SECTIONS OF IL. THIS
SYSTEM APRS TO HAVE FAVORABLE Q-G FORCING ACROSS THE SRN HALF OF
WI ALONG WITH ADDL LIFT PROVIDED BY THE LEFT EXIT RGN OF THE UPR
JET. HAVE KEPT POPS OVR CNTRL/E-CNTRL WI AT A HI CHC FOR NOW AS
THE GFS/CANADIAN ARE A BIT FARTHER SOUTH WITH BOTH THE SHRTWV TROF
AND SFC LOW COMPARED TO THE NAM AND TO A LESSER DEG...THE ECMWF.
IF THE LATTER SOLN IS CORRECT...SRN SECTIONS OF THE FCST AREA
COULD SEE AN INCH OR TWO OF ACCUMULATION BY DAYBREAK. THIS SYSTEM
TRACKS E-NE INTO THE ERN GREAT LKS ON MON...THUS MOST IF NOT ALL
OF ANY SNOW SHOULD COME TO AN END BY THE AFTERNOON. UP TO AN INCH
OF ADDL ACCUMULATION IS PSBL OVR E-CNTRL WI MON MORNING BEFORE
TAPERING OFF. BY MON AFTERNOON...WL NEED TO WATCH N-CNTRL WI AS
WNDS BACK N-NW AND LK EFFECT SNOW SHWRS KICK INTO GEAR. DELTA-T
VALUES ARE IN THE UPR TEENS AND LK-INDUCED CAPES ARE APPROACHING
400 J/KG WITH LITTLE IN THE WAY OF A LOW-LVL INVERSION. HAVE
RAISED POPS OVR VILAS CNTY UP TO 40 PERCENT FOR STARTERS AND WL
NEED TO WATCH THIS IN THE COMING DAYS.

LK EFFECT SNOW SHWRS ARE EXPECTED TO CONT INTO MON NGT ACROSS NRN
WI ALTHO EXPECT A WEAKENING TREND AS WNDS VEER DURING THE OVRNGT
HRS. ON TUE...ATTN IS FOCUSED OVR THE CNTRL/SRN PLAINS WHERE THE
MDLS APR TO BE GETTING INTO BETTER SYNC WITH A DEVELOPING STORM.
GULF MSTR WL ALREADY BE GETTING TAPPED WITH A 50 KT SOUTHERLY 
LOW-LVL JET QUICKLY BRINGING THE MSTR THRU THE MIDWEST AND INTO
THE WRN GREAT LKS. NE WI SHOULD ALREADY SEE CLDS THICKEN TUE
MORNING WITH INCREASING EASTERLY WNDS AND SNOW STARTING TO PUSH
INTO THE AREA TUE AFTERNOON.

WE COULD BE LOOKING AT OUR FIRST SIGNIFICANT WINTER STORM TUE NGT
INTO WED AS THE 00Z OPERATIONAL MDLS ARE RAPIDLY DEEPENING AN AREA
OF LOW PRES AND TAKING A FAVORABLE TRACK FROM THE SRN PLAINS THRU
NRN IL INTO LWR MI. HAVE RAISED POPS INTO THE HI CHC CATEGORY OVR
THE ENTIRE FCST AREA ON TUE NGT AND HAVE TWEAKED WED AS WELL.
DEPENDING ON THE EXACT TRACK OF THE STORM...NEAR BLIZZARD
CONDITIONS ARE PSBL SOMEWHERE OVR THE UPR MIDWEST/WRN GREAT LKS
WITH 6+" OF SNOW AND 30+ MPH SUSTAINED WNDS. LINGERING SNOW SHWRS/
FLURRIES ARE EXPECTED WED NGT BEFORE HI PRES BUILDS INTO THE RGN
FOR THU AND BRINGS CLEARING SKIES AND MORE TRANQUIL CONDITIONS.
&&

.AVIATION...LOW PRESSURE OVER THE WESTERN LAKES WILL CONTINUE TO
KEEP PLENTY OF CLOUDS OVER THE AREA. MAINLY VFR CIGS EXPECTED
TODAY WITH SCATTERED FLURRY ACTIVITY. BETTER CHANCE OF SNOW
SHOWERS OVERNIGHT WITH CONDITIONS TEMPORARILY DROPPING INTO MVFR RANGE.
&&

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

$$
TE/KALLAS