Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 140548
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1148 PM CST SAT DEC 13 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 221 PM CST SAT DEC 13 2014

MILD WEATHER TO CONTINUE.

THE WESTERLIES COMING OUT OF DEEP PERSISTENT UPR TROF OVER THE
ERN PAC WL REMAIN SPLIT AS THEY FLOW EWD ACRS NOAM. OTHER THAN A
SHRTWV BREAKING AWAY FM THE NRN STREAM AND CROSSING THE AREA DURING
THE WEEK...THE NRN STREAM WL REMAIN WELL N OF THE AREA. THE FCST
AREA WL REMAIN EITHER BETWEEN THE MAIN BRANCHES OF THE FLOW OR
UNDER THE INFLUENCE OF THE SRN STREAM.

THIS IS A MILD WX PATTERN FOR THE AREA. TEMPS WL BE MOSTLY ABV
NORMAL...WITH A BRIEF DROP BACK CLOSE TO NORMAL AS THE
AFOREMENTIONED NRN STREAM SYSTEM CROSSES THE AREA. PCPN AMNTS WL
END UP NR OR A LITTLE BLO NORMAL.
&&

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 221 PM CST SAT DEC 13 2014

FOG AND STRATUS WL DOMINATE THE WX IN THE SHORT TERM. VSBYS
IMPROVED A BIT MORE THAN ORIGINALLY EXPECTED THIS AFTN...PROBABLY
DUE TO WLY WINDS GENERATING A LITTLE MIXING OF THE LOW-LEVELS. BUT
AS THE GRADIENT DECREASES AND INCREASINGLY MOIST AIR FLOWS NWD
OVER THE SNOW COVER THIS EVENING...VSBYS AND CIGS SHOULD DROP
AGAIN. NOT REALLY MEETING CONDITIONS THAT WOULD WARRANT A FG.Y
RIGHT NOW...BUT PRETTY CONFIDENT WE/LL NEED ONE LATER THIS EVENING
AND OVERNIGHT. SO...WL CONTINUE TO WORK AROUND THE CURRENT
IMPROVEMENT IN CONDITIONS IN THE TEXT OF THE PRODUCTS AND ALLOW
THE ADVISORY THAT IS IN EFFECT TO RUN AS IS.

SML HOLE IN CLDS OVER NE WI WAS CLOSING UP THIS AFTN. ANY
LINGERING CLR AREAS OVER THE EXTREME NE CORNER COULD SEE TEMPS
DROP ABRUPTLY RIGHT AFTER SUNSET. OTHERWISE...EXPECT TEMPS TO
PRETTY MUCH HOLD STEADY OR EDGE SLOWLY UPWARD OVERNIGHT.

HIGHER DWPTS WL BE IN PLACE ACRS THE AREA TOMORROW...BUT BY THEN
MUCH OF THE SNOWCOVER WL BE GONE FROM AT LEAST THE SRN PART OF THE
FCST AREA. 18Z SUN SEEMS LIKE A GOOD FIRST GUESS AT AN ENDING TIME
FOR THE ADVISORY.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 221 PM CST SAT DEC 13 2014

NOT MUCH CHANGE IN THIS PERIOD FROM PREVIOUS TWO FORECAST CYCLES.
GENERAL MODEL AGREEMENT ON OVERALL PATTERN AS SPLIT MEAN FLOW
ACROSS U.S. CONTINUES.

FIRST SOUTHERN STREAM SYSTEM MOVES ACROSS N IL/SE WI BRINGING
MAINLY LIGHT RAIN INITIALLY. COLDER AIR BEHIND SYSTEM WILL CHANGE
RAIN TO SNOW WITH SOME ACCUM IN NORTHERN PART OF WI. ECMWF HAS
BEEN A BIT COLDER/FASTER THAN GFS...BUT CURRENT FORECAST LOOKS
REASONABLE SO LITTLE CHANGE NEEDED. STILL THINKING 2 OR 3 INCHES
POSSIBLE IN THE NORTH...WITH HIGHEST IN SNOWBELT AS SOME LAKE
EFFECT POTENTIAL AS WINDS BECOME FAVORABLE FOR LAKE SNOW/LAKE
ENHANCEMENT BEHIND DEPARTING SYSTEM. HOWEVER...AMOUNTS MAY BE
TEMPERED SOMEWHAT AS A PERIOD OF FREEZING RAIN/SLEET POSSIBLE
BEFORE SNOW CHANGEOVER AS LOW-LEVEL COLD AIR INITIALLY UNDERCUTS
COLUMN. DETAILS TO BE DETERMINED...SO WILL LEAVE OUT OF GRIDS FOR
NOW BUT WILL MENTION IN HWO.

THERE IS STILL SOME MODEL DIFFERENCES WITH THE TRAILING NORTHERN
STREAM WAVE. GFS IS ABOUT 6-12 HRS SLOWER THAN MORE PROGRESSIVE
ECMWF...WITH CLOUDS AND FLURRIES POSSIBLE INTO WED NIGHT.

A QUIET AND SOMEWHAT SEASONAL STRETCH OF WEATHER EXPECTED FOR THE
LATTER PART OF THE WORK WEEK AS THE SPRAWLING AREA OF HI PRESSURE
SETTLES OVER THE GREAT LAKES. LATE IN WEEK...NEXT SOUTHERN STREAM
SYSTEM IS FORECAST TO STAY SOUTH OF THIS PART OF STATE.

TEMPS FOR LONG TERM PART OF FORECAST MAINLY A MODEL BLEND.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1147 PM CST SAT DEC 13 2014

AT TAF ISSUANCE TIME...LIFR/IFR VSBYS AND CIGS COVERED CENTRAL AND NORTH
CENTRAL WISCONSIN...WHILE VSBYS AND CIGS AT LOCATIONS FARTHER TO
THE EAST WERE MAINLY MVFR BUT GRADUALLY LOWERING.

LIGHT WINDS...DEW POINTS WELL ABOVE NORMAL OVER SNOW-COVER...AND
INCREASING LOW LEVEL MOISTURE FROM MELTED SNOW CONTRIBUTED MUCH TO
THE DRIZZLE AND LOW VSBYS IN FOG.

EXPECT CONDITIONS TO BE MAINLY LIFR/IFR THROUGHOUT THE NIGHT WITH
SOME IMPROVEMENT DURING THE DAY ON SUNDAY TO MVFR...MAINLY WHERE
THERE IS LITTLE OR NO SNOW-COVER. CONDITIONS WILL PROBABLY
DETERIORATE AGAIN AROUND SUNSET.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL NOON CST SUNDAY FOR WIZ005-010>013-
018>022-030-031-035>040-045-048>050-073-074.
&&

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......JKL
AVIATION.......MG





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