Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 111653
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1153 AM CDT THU SEP 11 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 319 AM CDT THU SEP 11 2014

SEVERAL FCST CONCERNS TO DEAL WITH OVER THE NEXT 36 HOURS.
STARTING WITH TODAY...WL WE BE ABLE TO BUST SOME HOLES IN THE
THICK OVERCAST AND WOULD ANY SUNSHINE HELP TEMPS? FOR TNGT...
HOW FAST WL CLOUDS RETURN TO THE AREA AND WL THEY ARRIVE QUICK
ENUF TO PREVENT A WIDESPREAD FROST IN THE NORTH? FOR THU...HOW
FAST WL PCPN CHCS ARRIVE?

THE 07Z MSAS SFC ANALYSIS INDICATED A STRONG AREA OF LOW PRES
ALONG THE SE ONTARIO/SW QUEBEC BORDER WITH A CDFNT STRETCHED SW TO
THE MID-MS VALLEY. A STRONG AREA OF HI PRES WAS SITUATED OVER THE
CANADIAN ROCKIES WITH A TIGHT PRES GRADIENT OVER THE GREAT LAKES
RESULTING IN GUSTY N-NW WINDS. SATL IMAGERY SHOWED PLENTY OF
CLOUDS OVER ALL OF WI WITH SFC REPORTS PICKING UP A LITTLE DRIZZLE
OVER VILAS COUNTY.

CANNOT RULE OUT LINGERING LIGHT RAIN SHWRS OR DRIZZLE ACROSS
N-CNTRL WI THIS MORNING AS THE COMBINATION OF WEAK LAKE EFFECT AND
CYCLONIC FLOW TO PERSIST. EVEN THO NORTH WINDS TO CONT THIS
AFTERNOON...FLOW ALOFT TURNS MORE ANTICYCLONIC WHICH WOULD BRING
PCPN CHCS TO AN END. FOR THE REST OF NE WI...FCST SOUNDINGS SHOW
PLENTY OF LOW-LEVEL MOISTURE TRAPPED UNDER AN INVERSION INTO AT
LEAST EARLY AFTERNOON...THUS MOSTLY CLDY SKIES EXPECTED FOR MOST
OF THE DAY. THIS INVERSION DOES EVENTUALLY DISSIPATE AND THERE MAY
BE SOME PEEKS OF SUN LATE THIS AFTERNOON. THE BIGGER STORY FOR
TODAY TO BE THE CHILLY AIR MASS OVER THE REGION WITH 8H TEMPS JUST
ABOVE 0C. MAX TEMPS TO RANGE FROM THE UPR 40S TO LWR 50S NORTH...
MID TO MID 50S SOUTH. THIS WOULD BE ABOUT 15 DEGS BELOW NORMAL FOR
MID-SEPT.

ANY BREAKS IN THE CLOUD COVER TO BE SHORT-LIVED AS THE MDLS ALL
SHOW AN IMPRESSIVE SHORTWAVE TROF TO DIG ACROSS THE NRN/CNTRL
PLAINS TNGT. AFTER A PARTLY CLDY EVENING...LOOK FOR MID AND HI
CLOUDS TO ROLL BACK INTO THE FCST AREA DURING THE OVRNGT HOURS.
THESE CLOUDS MAY ACTUALLY HELP TO PREVENT A WIDESPREAD FROST FROM
DEVELOPING AS MIN TEMPS ARE EXPECTED TO DIP INTO THE 30S OVER NRN
AND PARTS OF CNTRL WI. PATCHY FROST WAS ALREADY ADDED TO THE FCST
ACROSS THE NORTH AND SEE NO REASON TO CHANGE THIS POTENTIAL. IF
THESE CLOUDS DO NOT ARRIVE FAST ENUF...THE DAY SHIFT MAY HAVE TO
CONTEMPLATE AN ADVY. BOTTOM LINE...IF YOU HAVE TENDER VEGETATION...
PLAY IT SAFE AND COVER THEM OR BRING SENSITIVE PLANTS INDOORS TNGT.

THIS SHORTWAVE TROF SWEEPS EWD INTO THE UPR MS VALLEY/MIDWEST ON
FRI AND WL BRING THE NEXT CHC OF PCPN TO NE WI. EVEN THO THERE ARE
NO RELEVENT SFC FEATURES TO FOCUS THE PCPN...THIS IS A DYNAMIC
LITTLE SYSTEM WITH STRONG MID-LEVEL FORCING AND A DIFFLUENT FLOW
ALOFT. THE BETTER PV ADVECTION TO BE OVER SRN SECTIONS OF WI...
THUS HIGHER POPS PLACED OVER CNTRL/E-CNTRL WI. QPF AMOUNTS TO BE
MUCH LESS THAN PREVIOUS EVENTS WITH MOST LOCATIONS RECEIVING
BETWEEN 0.10 AND 0.25". A COOL START TO FRI PLUS THE ONSET OF PCPN
WL TRANSLATE TO ANOTHER UNSEASONABLY COOL DAY WITH MAX TEMPS IN
THE LWR TO MID 50S NORTH...MID 50S SOUTH.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 319 AM CDT THU SEP 11 2014

AN UPPER LEVEL TROUGH WILL CONTINUE TO MOVE AWAY FROM WISCONSIN
DURING THE EARLY PART OF THIS FORECAST PERIOD. SHOWERS ASSOCIATED
WITH THE TROUGH ARE EXPECTED TO BE ON THE WAY OUT OF THE AREA ON
FRIDAY NIGHT. A LARGE SURFACE HIGH AND VERY WEAK UPPER RIDGE
SHOULD HELP TO KEEP THINGS DRY FOR SATURDAY AND SATURDAY NIGHT. A
CHANCE OF SHOWERS THEN RETURNS TO NORTH CENTRAL WISCONSIN ON
SUNDAY AS UPPER SHORT WAVE ENERGY AND A COLD FRONT APPROACH THE
STATE. RAIN CHANCES SPREAD ACROSS THE REST OF THE AREA FOR SUNDAY.
THE RAIN SHOULD END FROM NORTH TO SOUTH AS THE FRONT PASSES
THROUGH THE STATE. SURFACE HIGH PRESSURE MOVING INTO THE REGION
BEHIND THE DEPARTING FRONT SHOULD KEEP THE AREA DRY THROUGH THE
END OF THE FORECAST PERIOD.

00Z MAV AND MET GUIDANCE HAVE SOME SUBZERO LOWS IN NORTH CENTRAL
WISCONSIN FRIDAY NIGHT/SATURDAY MORNING. NO HEADLINES FOR FROST
OR FREEZING TEMPERATURES AT THIS POINT. THERE IS STILL SOME
UNCERTAINTY SURROUNDING THE DEPARTURE TIME OF THE SHOWERS. IT
IS ALSO POSSIBLE THAT CONDITIONS IN THAT AREA WILL BE TOO WET AND
THE LATENT HEAT OF FUSION WILL PREVENT FROST FROM FORMING AND
KEEP TEMPERATURES FROM DROPPING BELOW FREEZING.

HIGHS ON SATURDAY WILL PROBABLY NOT MAKE IT OUT OF THE 50S IN MOST
LOCATIONS...BUT A SLIGHT WARMING TREND IS EXPECTED FOR THE EARLY
PART OF NEXT WEEK. EVEN SO...HIGH TEMPERATURES SHOULD BE AROUND 5
DEGREES BELOW NORMAL.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1153 AM CDT THU SEP 11 2014

WIDESPREAD BROKEN MVFR CIGS WILL PREVAIL FOR MUCH OF THE
AFTERNOON...THOUGH EXPECTING CIGS TO SLOWLY RISE...POSSIBLY TO VFR
BY 22-00Z.  DIFFICULT TO ESTIMATE WHEN BKN CIGS WILL SCATTER DUE TO
NORTHERLY UNSTABLE FLOW OFF LAKE SUPERIOR CONTINUING THROUGH THE
NIGHT.  THE BEST GUESS IS SOMETIME THIS EVENING WHEN THIS FLOW OFF
LAKE SUPERIOR LIGHTENS AND THE INVERSION WEAKENS.  BUT IF THE
NOCTURNAL INVERSION DUE TO COOLING TRAPS THE RESIDUAL MOISTURE IN
THE BOUNDARY LAYER...THEN BKN CLOUDS COULD STICK AROUND FOR MUCH OF
THE NIGHT.  IF CLOUDS DO SCATTER...THEN BKN CIGS WILL LIKELY DEVELOP
AGAIN BY MIDDAY TOMORROW AHEAD OF THE NEXT UPPER DISTURBANCE.
&&

.MARINE...
ISSUED AT 319 AM CDT THU SEP 11 2014

WINDS HAVE STARTED TO DIMINISH OVER ERN WI AS THE STRONG
SFC LOW CONTS TO PULL FARTHER AWAY. PLAN TO REDUCE THE BAY BACK TO
A SMALL CRAFT TO START THE DAY AND THEN LIKELY EXPIRE THE GALE
EAST OF DOOR COUNTY BY MID-MORNING.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......MG
AVIATION.......MPC
MARINE.........KALLAS






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