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000
FXUS63 KGRB 300047
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
647 PM CST FRI NOV 29 2013

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 247 PM CST FRI NOV 29 2013

BIG QUESTION FOR TONIGHT IS WHETHER THERE WILL BE
FREEZING DRIZZLE OR LIGHT SNOW IN THE NORTH AS STRONG LOW LEVEL
WARM ADVECTION COMBINES WITH THE RIGHT ENTRANCE REGION OF AN UPPER
JET TO PRODUCE VERTICAL MOTION. THE AIR IS INITIALLY VERY DRY SO
ANY PRECIPITATION WOULD BE VERY LIGHT. FORECAST SOUNDINGS SUGGEST
THAT THE SATURATED LAYERS ARE GENERALLY ABOVE -5C SO IT APPEARS
THAT FREEZING DRIZZLE WOULD BE MORE LIKELY THAN SNOW...BUT
DIFFICULT TO SAY FOR SURE. LOWS TONIGHT SHOULD BE IN THE EARLY
EVENING WITH STEADY OR SLOWLY RISING TEMPERATURES OVERNIGHT WITH
CLOUDS AND A BREEZE. HIGHS SATURDAY SHOULD GET ABOVE FREEZING IN
THE EAST BEFORE THE ARRIVAL OF A WEAK COLD FRONT.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 247 PM CST FRI NOV 29 2013

MDLS ARE AT LEAST A LITTLE BETTER IN SYNC WITH THE MAJOR PATTERN
CHANGE FOR NEXT WEEK. AS A STRONG UPR RDG BUILDS INTO ALASKA...A
PROMINENT LONGWAVE TROF WL DIG ACROSS THE WRN THIRD OF THE CONUS.
THE FCST ISSUES CENTER MORE ON THE LOWER LEVELS OF THE ATMOSPHERE
AS THE MDLS ARE HANDLING THE EWD MOVING CDFNT/AREAS OF LOW PRES
DIFFERRENTLY. THE MEAN FLOW CHANGE TO THE SW OVER THE CNTRL CONUS
WL ALLOW FOR A MILDER/MORE ACTIVE WEATHER PATTERN TO DEVELOP WITH
PCPN CHCS NECESSARY ALMOST EVERY DAY.

THE CDFNT CONTS TO MOVE AWAY FROM WI SAT NGT AS A SFC RDG BUILDS
ACROSS THE UPR MS VALLEY. SLIGHTLY COOLER AIR TO OVERSPREAD THE
REGION ON NORTHERLY WINDS AND THIS INCREASES THE THREAT FOR LAKE
EFFECT SNOW SHWRS FOR NRN WI. THIS LOOKS TO BE A MINOR EVENT AS
TRAJS ARE NOT PERFECT...DELTA-T VALUES ONLY TO BE IN THE LWR TO
MID TEENS AND INVERSION HEIGHTS TO SIT AROUND 4K FT. HAVE KEPT
POPS ONLY IN THE CHC CATEGORY FOR VILAS CNTY WITH VERY LITTLE IN
THE WAY OF SNOW ACCUMULATIONS. THE REST OF THE FCST AREA SHOULD
SEE SKIES BECOME PARTLY CLOUDY WITH MIN TEMPS RANGING FROM THE UPR
TEENS TO THE MID 20S.

AS THE SFC RDG MOVES INTO THE WRN GREAT LAKES ON SUNDAY...WINDS
ARE EXPECTED TO GRADUALLY VEER TO THE NE WHICH WOULD ESSENTIALLY
END THE LAKE EFFECT THREAT FOR VILAS CNTY. WL HAVE TO WATCH LAKE
EFFECT POTENTIAL FROM LAKE MI LATER IN THE DAY AS THE WINDS BECOME
NE...BUT FEEL ANY LAKE BANDS WL NOT HAVE HAD TIME TO DEVELOP (AT
LEAST DURING THE DAYLIGHT HOURS). OTHERWISE...A DRY DAY EXPECTED
WITH A GENERAL INCREASE IN HI CLOUDS DURING THE AFTERNOON AS A
WEAK SYSTEM MOVES ACROSS THE NRN PLAINS. MAX TEMPS SHOULD BE AT
LEAST NEAR NORMAL FOR THE FIRST DAY OF DECEMBER...IF NOT A DEG OR
TWO ABOVE NORMAL.

CLOUDS WL CONT TO STEADILY INCREASE/THICKEN OVER NE WI SUNDAY NGT
AS THE SHORTWAVE TROF MOVES INTO THE UPR MS VALLEY. WEAK MID-LEVEL
FORCING STILL FOCUSED TO OUR WEST...THUS EXPECT MOST OF THE NGT WL
REMAIN DRY. STILL NEED TO WATCH THE LAKE EFFECT FROM LAKE MI AS
WINDS START FROM THE NE...BUT IS FCST TO VEER MORE EAST OVRNGT.
THIS VEERING WL MAKE IT HARD FOR A CONSISTENT BAND TO DEVELOP...
THUS DO NOT ANTICIPATE MUCH MORE THAN ISOLATED SNOW SHWRS OR
FLURRIES. EVEN THO THE AIR MASS ALOFT IS SLIGHTLY COLDER SUNDAY
NGT...THE INCREASE IN CLOUDS WL OFFSET THIS COOLING AND LEAVE MIN
TEMPS CLOSE TO VALUES SEEN SAT NGT. THIS SHORTWAVE TROF MAKES ITS
WAY ACROSS WI ON MON WITH WEAK FORCING...MARGINAL INSTABILITY AND
NO JET SUPPORT ALOFT. THIS POINTS TO A RATHER MINOR SNOW EVENT FOR
NE WI AND WL KEEP POPS ON THE LOW SIDE AS A RESULT. WINDS TO
REMAIN FROM THE EAST WHICH WL LIMIT THE FETCH...THEREBY MAKE ANY
LAKE EFFECT POTENTIAL NEGLIGIBLE. MAX TEMPS TO AGAIN RANGE FROM
AROUND 30 NORTH TO THE MID 30S OVER E-CNTRL WI.

KEPT A SMALL POP IN THE FCST INTO MON EVENING AS THE SHORTWAVE
TROF TO STILL BE IN THE PROCESS OF EXITING THE AREA. CHANGES IN
THE MEAN FLOW BECOME MORE NOTICEABLE BY TUE AS THE UPR TROF DIGS
S-SE ACROSS THE WRN CONUS AND WEAK DOWNSTREAM UPR RIDGING DEVELOPS
OVER THE E-CNTRL CONUS. HARD TO SEE ANY LIFT OR FORCING FROM THE
MDLS AS THE STRONGEST ISEN LIFT TO BE SITUATED OVER THE NRN
PLAINS/UPR MS VALLEY. PREFER TO GO DRY FOR THE LATTER PART OF MON
NGT THRU TUE.

THE FCST FOR THE MID TO LATE WEEK PERIOD IS STILL A MESS WITH EACH
LONG-TERM MDL OFFERING A COMPLETELY DIFFERENT SCENARIO. THIS IS
ESPECIALLY TRUE FOR THE WED-THU TIME FRAME WITH THE TIMING/LOCATION
OF A SFC LOW/CDFNT LIFTING E-NE ACROSS THE CNTRL CONUS. BELIEVE THE
GFS IS JUST TOO QUICK IN LIFTING/EJECTING THE UPR TROF NEWD...
THEREBY RACING THE CDFNT EWD TOO FAST. UNDER ANY AMPLIFIED PATTERN...
SLOWER SEEMS THE WAY TO GO WHICH WOULD FAVOR THE ECMWF IN THIS CASE.
THIS SCENARIO WOULD BRING AT LEAST A SMALL CHC FOR ISEN LIFT-INDUCED
PCPN TO NE WI ON WED WITH ENUF WARMING AT THE SURFACE FOR A POTENTIAL
RAIN/SNOW MIX FOR CNTRL/E-CNTRL WI. AS THE PRIMARY SFC LOW LIFTS NE
FROM THE CNTRL PLAINS THRU THE UPR MS VALLEY WED NGT/THU...THE CDFNT
WOULD SWING THRU WI AND BRING A BETTER CHC FOR PCPN. PCPN TYPE COULD
AGAIN BE AN ISSUE AS WARMER AIR GETS PULLED NWD AHEAD OF THE FNT.
HAVE KEPT A RAIN/SNOW MIX IN THE FCST FOR ROUGHLY THE SE HALF OF
THE FCST AREA DUE TO THE UNCERTAINTY INVOLVED.

STRONG CAA POURS INTO WI BEHIND THE CDFNT FOR LATE IN THE WEEK AS
GUSTY WEST WINDS DEVELOP OVER THE REGION. A POTENTIAL DRY SLOT
WOULD KEEP THIS PERIOD MAINLY ON THE DRY SIDE WITH MORE OF THE
FOCUS ON THE ARCTIC SURGE HEADED INTO NEXT WEEKEND.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 645 PM CST FRI NOV 29 2013

MAIN ISSUE IS TO WHAT EXTENT LOW CLDS FORM TNGT. EXPECT SC DECK TO
INCR...THOUGH CIGS WL PROBABLY REMAIN PRIMARILY IN VFR CATEGORY.
CARRIED LLWS AT ALL TAF SITES AS SWLY WINDS INCR ALOFT.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......SKOWRONSKI