Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 110252
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
952 PM CDT WED SEP 10 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 242 PM CDT WED SEP 10 2014

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG
LOW PRESSURE SYSTEM TRACKING NORTHEAST TOWARDS MANITOWOC WHILE A
POTENT COLD FRONT IS DROPPING SOUTHEAST FROM THE BAY OF GREEN BAY TO
JUST WEST OF OSHKOSH.  MOST OF THE HEAVIER RAINFALL HAS EXITED THE
REGION TO THE NORTHEAST EXCEPT FOR FAR WESTERN ONEIDA AND VILAS
COUNTIES.  AREAS OF DRIZZLE OR VERY LIGHT RAIN WILL GRADUALLY
DIMINISH THROUGH THE REST OF THE AFTERNOON AS THE CYCLONE EXITS THE
REGION.  OBSERVATIONS INDICATE A WIDESPREAD 1.5 TO 2.5 INCHES OF
RAIN OVER NORTH-CENTRAL WISCONSIN FOR A STORM TOTAL.  AREA RIVERS
SEEM TO BE HOLDING UP WELL AND HAVE RECEIVED NO REPORTS OF FLOODING
SO FAR.  WILL LET THE FLOOD WATCH EXPIRE WITH THIS FORECAST
ISSUANCE.  GUSTY NORTHWEST WINDS ARE USHERING IN THE FIRST TASTE OF
FALL BEHIND THE COLD FRONT.  TEMPERATURES ARE FALLING INTO THE 40S
AND 50S BEHIND THE FRONT...WHILE READINGS REMAIN IN THE 60S AND 70S
AHEAD OF THE FRONT.  TIMING THE END OF THE PRECIP...TEMPS...AND
MARINE HEADLINES ARE THE MAIN FORECAST CONCERNS.

TONIGHT...LOW PRESSURE WILL CONTINUE TO MOVE TO THE NORTHEAST INTO
EASTERN ONTARIO AND WESTERN QUEBEC WHILE THE STRONG COLD FRONT MOVES
EAST ACROSS THE LOWER PENINSULA OF MICHIGAN.  BEHIND THE
FRONT...GUSTY NORTHWEST WINDS WILL USHER IN A MIGHTY CHILLY AIRMASS
FOR THIS TIME OF THE YEAR.  WITH LOW INVERSION HEIGHTS OF AROUND
875MB...THE AIRMASS WILL BE PLENTY COLD ENOUGH TO SUPPORT LAKE
EFFECT RAIN SHOWERS OFF LAKE SUPERIOR...WHICH WILL LIKELY JUST
IMPACT VILAS COUNTY AS WIND TRAJECTORIES ARE TOO NORTHERLY FOR A
DIRECT HIT.  PLENTY OF LOW STRATUS UPSTREAM BENEATH THIS
INVERSION...AND WITH MOISTURE FLUXES OFF LAKE SUPERIOR COMBINED WITH
THERMAL TROUGHING...HAVE A TOUGH TIME SEEING ANY SORT OF CLEARING
TAKING PLACE.  PERHAPS A FEW HOLES IN THE OVERCAST IN THE
DOWNSLOPING AREAS OF NORTHEAST WISCONSIN.  LOWS FALLING INTO THE
UPPER 30S NORTH TO UPPER 40S SOUTHEAST.

THURSDAY...850MB TEMPERATURES CONTINUE TO FALL AS CANADIAN HIGH
PRESSURE BUILDS TOWARDS THE REGION.  THE INVERSION WILL REMAIN STOUT
ABOVE STEEP LOW LEVEL LAPSE RATES.  AS A RESULT...CLOUDY CONDITIONS
IN THE MORNING WILL BE SLOW TO BREAK UP...ESPECIALLY WITH MID-LEVEL
CLOUDS ARRIVING IN THE AFTERNOON.  SO EXPECT SKY CONDITIONS TO
REMAIN AT LEAST PARTLY SUNNY OR MOSTLY CLOUDY THROUGH THE
DAY.  HIGHS RANGING FROM THE UPPER 40S NORTH TO MIDDLE 50S SOUTH.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 242 PM CDT WED SEP 10 2014

LARGE SURFACE HIGH SHOULD COVER THE NORTHERN AND
CENTRAL PLAINS ALL THE WAY EAST TO THE GREAT LAKES AND NORTHERN
OHIO VALLEY THURSDAY NIGHT THROUGH FRIDAY EVENING. WHILE THIS
WOULD NORMALLY RESULT IN A DRY FORECAST AND CLEAR SKIES THERE IS A
SHARP UPPER LEVEL TROUGH THAT WILL BE MOVING ACROSS WISCONSIN
FRIDAY AND FRIDAY EVENING THAT SHOULD BE STRONG ENOUGH TO PRODUCE
SOME LIGHT RAIN DESPITE SURFACE HIGH PRESSURE AND DRY AIR IN THE
LOW LEVELS. THE CLOUDS AND LIGHT RAIN SHOULD KEEP HIGH TEMPERATURES
LOWER THAN MOS GUIDANCE FRIDAY SO WENT ABOUT 3 DEGREES LOWER IN
MOST PLACES.

LOW TEMPERATURES SATURDAY MORNING WILL DEPEND ON HOW QUICKLY THE
UPPER SYSTEM EXITS FRIDAY NIGHT AND HOW QUICKLY SKIES CLEAR. THE
ECMWF IS SLOWER THAN THE GFS AND ITS SOLUTION WOULD KEEP CLOUDS
ALL NIGHT AND HOLD TEMPERATES UP. WE ARE SIDING WITH THE QUICKER
GFS AND THUS WENT LOWER THAN GUIDANCE FOR LOWS FRIDAY NIGHT.

NICE WEATHER EXPECTED SATURDAY THROUGH SUNDAY WITH A SLIGHT CHANCE
OF SHOWERS SUNDAY EVENING AS THE NEXT UPPER TROUGH APPROACHES.
THAT SYSTEM SHOULD BRING SHOWERS SUNDAY NIGHT AND MONDAY.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 950 PM CDT WED SEP 10 2014

CIGS MAINLY BETWEEN 1200 TO 2200 FT OVERNIGHT. CIGS IMPROVING ON
WEDNESDAY.

WIND GUSTS OF 25 TO 30 KTS EARLIER THIS EVENING HAVE BEEN
GRADUALLY DECREASING. GUSTS OVER 30 KTS IN FAR EASTERN AIRPORTS
ALONG AND EAST OF FOX VALLEY...ESPECIALLY DOOR COUNTY...WITH
CONDITIONS IMPROVING OVERNIGHT.

&&

.MARINE...
ISSUED AT 242 PM CDT WED SEP 10 2014

NORTHWEST WINDS WILL RAPIDLY STRENGTHEN LATE THIS
AFTERNOON INTO EARLY THIS EVENING BEHIND A DEPARTING LOW PRESSURE
SYSTEM.  WITH INCREASING INSTABILITY OVER THE CENTRAL BAY OF GREEN
BAY...MIXING WILL SUPPORT 40 TO 45 KT WINDS AT 925 AND 900MB TO
REACH THE SURFACE.  THIS WIND DIRECTION IS ALSO FAVORABLE FOR HIGHER
END GUSTS THROUGH DEATHS DOOR.  ISSUE A GALE WARNING FOR THE CENTRAL
BAY AND LAKE MICHIGAN SHORELINE THROUGH 18Z...THOUGH GALES WILL
LIKELY ONLY BE POSSIBLE THROUGH SUNRISE ON THURSDAY.
&&

.HYDROLOGY...
ISSUED AT 636 PM CDT WED SEP 10 2014

NORTH-CENTRAL WISCONSIN PICKED UP THE MOST RAINFALL FOR THIS
EVENT...WITH SCATTERED LOCATIONS REACHING 2 TO 3 INCHES. RIVERS
STARTING TO RESPOND...WITH A COUPLE NEAR BANKFULL. BIG RIB RIVER
IN MARATHON COUNTY AT FLOOD STAGE...BUT NO SIGNIFICANT PROBLEMS ATTM.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......JKL
MARINE.........MPC
HYDROLOGY......JKL






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