Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 151709
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1109 AM CST MON DEC 15 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 321 AM CST MON DEC 15 2014

FOG TODAY INTO THIS EVENING...LIGHT RAIN COVERAGE LATER TODAY
INTO THIS EVENING AND THEN A TURN TO SNOW LATER TONIGHT INTO
TUESDAY WILL PROVIDE PLENTY OF FORECAST CHALLENGERS EARLY THIS
WEEK.

SURFACE ANALYSIS SHOWS ONE LOW PRESSURE SYSTEM CENTERED OVER
NORTHERN MINNESOTA CONNECTED BY A TROUGH TO THE PRIMARY LOW
PRESSURE SYSTEM OVER THE CENTRAL PLAINS. SOME WEAK LIGHT RAIN OR
DRIZZLE PASSED OVER NORTHERN WISCONSIN EARLIER TONIGHT WITH THIS
NORTHERN LOW. OTHERWISE WILL HAVE TO WAIT FOR THE BAND OF LIGHT
RAIN ASSOCIATED WITH THE SOUTHERN LOW PRESSURE TO APPROACH LATER
THIS AFTERNOON INTO THIS EVENING. MUCH OF THE FORECAST AREA WILL
REMAIN IN THE LOW STRATUS AND DENSE FOG. WILL CONTINUE GOING
HEADLINE TO NOON AND WILL ADD THE REST OF THE LAKESHORE COUNTIES
AS WEB CAMS AND OBS SHOWING DENSE FOG. ACKNOWLEDGE AND
EXTENSION OF THE FOG HEADLINES MAY BE NEEDED OVER PARTS OF THE AREA
THIS AFTERNOON. IN THE AFTERNOON APPROACHING RAIN MAY BEGIN TO
IMPROVE CONDITIONS SLIGHTLY.

LIGHT RAIN AND DRIZZLE WILL CONTINUE TO OVERSPREAD THE AREA AS THE
LOW PRESSURE SYSTEM TRACKS OVER SOUTHEAST WISCONSIN. STUCK PRETTY
TO CLOSE ONGOING FORECAST OF THE TRANSITION TO SNOW FROM
NORTHWEST TO SOUTHEAST LATER TONIGHT INTO TUESDAY. AN INCH OR TWO
OF SNOW ACCUMULATION STILL EXPECTED MAINLY NORTH OR NORTHWEST OF
RHI THROUGH NOON TUESDAY.

TUESDAY MORNING LOWS AND HIGHS WILL CHANGE LITTLE WITH THE FALLING
TEMPERATURES LATER TONIGHT INTO TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 321 AM CST MON DEC 15 2014

SPLIT FLOW WL CONT INTACT ACROSS NOAM THRU NEXT WEEKEND WITH A NRN
STREAM RUNNING MAINLY ACROSS SRN CANADA AND A SRN STREAM RUNNING
OVER THE SRN HALF OF THE CONUS. MAIN WEATHER FEATURES TO BE A NRN
STREAM UPR LOW MOVING ACROSS THE GREAT LAKES TUE NGT/WED...A SRN
STREAM SYSTEM PASSING TO OUR SOUTH LATE THIS WEEK AND A NRN STREAM
SHORTWAVE TROF DROPPING SE INTO THE GREAT LAKES NEXT SUNDAY.
OVERALL...PCPN CHCS APPEAR MINIMAL OTHER THAN SOME MINOR LAKE
EFFECT OVER THE NORTHWOODS MID-WEEK. TEMPS TO SETTLE AT OR
SLIGHTLY ABOVE NORMAL THRU THE EXTENDED FCST.

MODELS ARE IN GOOD AGREEMENT WITH REGARDS TO DROPPING A NRN STREAM
UPR LOW INTO THE WRN GREAT LAKES TUE NGT. DESPITE A STRONG EMBEDDED
SHORTWAVE...IT WL BE HARD FOR THIS SYSTEM TO GENERATE PCPN AS
MOISTURE TO HAVE BEEN STRIPPED AWAY BY THE PREVIOUS SYSTEM. THERE
MAY BE A FEW FLURRIES...OTHERWISE THE MAIN FOCUS FOR TUE NGT WL BE
A LIGHT LAKE EFFECT SNOW SHWR EVENT FOR N-CNTRL WI. 8H TEMPS ARE
FCST TO FALL INTO THE MID-TEENS(C) OVER LAKE SUPERIOR AND DELTA-T
VALUES IN TO THE UPR TEENS ARE POSITIVES FOR SNOW ACCUMULATION. A
RELATIVELY LOW INVERSION HEIGHT AND TRAJS ONLY MARGINALLY FAVORABLE
ARE NEGATIVES. THEREFORE...SNOW ACCUMULATIONS FOR VILAS CNTY SHOULD
BE AN INCH OR LESS WITH ONLY A DUSTING FARTHER SOUTH AND EAST. AS
FOR TEMPS...LOOK FOR READINGS TO DIP INTO THE 10-15 DEG RANGE
NORTH...LWR 20S E-CNTRL WI.

THIS UPR LOW IS FCST TO WEAKEN AND QUICKLY SHIFT TOWARD THE ERN
GREAT LAKES ON WED. LINGERING SNOW SHWRS TO PERSIST OVER N-CNTRL WI
WITH AN ADDITIONAL MINOR ACCUMULATION (< 1") ACROSS VILAS CNTY.
SOME PEEKS OF SUNSHINE ARE POSSIBLE ACROSS CNTRL/E-CNTRL WI...BUT
EXPECT MORE CLOUDS THAN SUN AS A CYCLONIC FLOW LINGERS OVER WI. MAX
TEMPS TO RANGE FROM THE LWR 20S NORTH TO THE UPR 20S E-CNTRL WI.

CANADIAN HI PRES BEGINS TO SETTLE SOUTH ACROSS THE UPR MS VALLEY/
MIDWEST AND TRY TO SEND DRIER AIR INTO WI WED NGT. THIS SHOULD
BEGIN TO DIMINISH THE SNOW SHWR THREAT OVER N-CNTRL WI...BUT WL
CONT TO CARRY A SMALL POP THRU THE NGT. MORE CLOUDS NORTH/LESS
CLOUDS SOUTH WL LEAD TO A UNIFORM TEMPERATURE SPREAD ACROSS NE WI.
LOOK FOR MIN TEMPS TO GENERALLY SETTLE INTO THE TEENS. THE HI PRES
EVENTUALLY SPREADS INTO THE WRN GREAT LAKES REGION ON THU AND BRING
DRY WEATHER TO THE FCST AREA UNDER PARTLY CLOUDY SKIES. MAX TEMPS
ARE EXPECTED TO BE CLOSE TO NORMAL WITH LWR 20S NORTH TO THE UPR
20S E-CNTRL WI. THIS AREA OF HI PRES WL BE OUR MAIN WEATHER FEATURE
THRU FRI WITH MORE PARTLY CLOUDY SKIES AND SEASONAL TEMPS BY
DECEMBER STANDARDS.

THE MAIN ISSUE FOR THE START OF THE WEEKEND WL BE THE MOVEMENT OF
A SRN STREAM SYSTEM TRACKING ACROSS THE ERN THIRD OF THE CONUS.
THE GFS MAINTAINS A MORE NRN TRACK UP THE OHIO RIVER VALLEY AND
BRINGS THE NRN EDGE OF LIGHT SNOW THRU SRN WI. THE GEM/ECMWF KEEP
THIS SYSTEM WELL TO OUR SOUTH (THRU THE SE CONUS TO THE MID-ATLANTIC
STATES) AND MAINTAINS THE HI PRES OVER THE GREAT LAKES. PREFER TO
STAY THE COURSE AND FOLLOW THE GEM/ECMWF WITH THE HI PRES OVER THE
GREAT LAKES ACTING LIKE A BLOCK AND HELPING TO FORCE A MORE SRN
TRACK. FCST UNCERTAINTY CONTS INTO NEXT SUNDAY WITH THE HANDLING
OF A NRN STREAM SHORTWAVE TROF PROGGED TO DIG SE INTO THE GREAT
LAKES. QUESTIONS REMAIN AS TO WHETHER THIS SYTEM WL DIVE TOWARD WI
OR POINTS FARTHER EAST. AT THIS POINT...FOLLOWED THE CONSENSUS
SOLUTION WHICH KEEPS NE WI DRY FOR NOW. TEMPS NEXT WEEKEND ARE
EXPECTED TO BE SLIGHTLY ABOVE NORMAL AS ARCTIC AIR REMAINS LOCKED
WELL NORTH IN CANADA.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1105 AM CST MON DEC 15 2014

IFR/LIFR CIGS AND VSBYS WILL CONTINUE THIS AFTERNOON WITH THE
WORST CONDITIONS IN CENTRAL AND NORTH CENTRAL WISCONSIN. AS LIGHT
RAIN SPREADS OVER THE AREA THIS AFTERNOON...SOME SLIGHT
IMPROVEMENT IN CIGS AND VSBYS POSSIBLE BUT SHOULD REMAIN IN
IFR/LOW MVFR RANGE. IFR CIGS AND VSBYS WILL CONTINUE TONIGHT AS
LIGHT RAIN BECOMES MORE WIDESPREAD. WINDS WILL BACK NORTH THROUGH
THE NIGHT...AND THUS RAIN MIXES WITH THEN TURNS TO SNOW FROM
NORTHWEST TO SOUTHEAST LATER TONIGHT AND TUESDAY MORNING. SNOW
SHOULD REMAIN LIGHT WITH LITTLE TO NO ACCUMULATION FOR TAF SITES
IN NE WI.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ005-
010>013-018>021-030-031-035>038-073-074.
&&

$$

SHORT TERM.....TDH
LONG TERM......KALLAS
AVIATION.......ALLEN





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