Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 211758
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1258 PM CDT TUE OCT 21 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 315 AM CDT TUE OCT 21 2014

THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE CENTERED OVER ONTARIO AND A SURFACE RIDGE AXIS RUNNING
SOUTHWEST OVER THE NORTHERN MISSISSIPPI VALLEY AND CENTRAL PLAINS.
EAST OF THE RIDGE AXIS...NORTH TO NORTH NORTHEAST FLOW CONTINUES
OVER THE WESTERN GREAT LAKES.  THE COMBO OF UNSTABLE CONDITIONS OVER
LAKE SUPERIOR AND THERMAL TROUGHING ARE CONTRIBUTING TO WIDESPREAD
STRATO-CU ACROSS THE NORTHEAST HALF OF WISCONSIN.  AREA OBS ARE
STILL REPORTING SPOTTY SPRINKLES.  FURTHER NORTH...DRIER AIR IS
WORKING SOUTHWARD OVER LAKE SUPERIOR.  LOOKING UPSTREAM...A STRONG
UPPER LEVEL RIDGE EXITS OVER THE CENTRAL OF THE CONTINENT WHICH IS
LEADING TO CLEAR AND QUIET CONDITIONS.  FORECAST CONCERNS INCLUDE
CLOUDS TRENDS TODAY FOLLOWED BY TEMPS.

TODAY...NOT AN EASY CLOUD FORECAST TODAY.  HIGH PRESSURE WILL BE
BUILD SOUTHWARD OUT OF ONTARIO...BUT 925MB THERMAL TROUGHING AND
NORTH TO NNE FLOW CONTINUE OFF LAKE SUPERIOR.  WITH LOWERING
INVERSION HEIGHTS AND UNSTABLE CONDITIONS OVER LAKE SUPERIOR...THINK
CLOUDS WILL CONTINUE TO HANG AROUND OVER N-C AND MOST OF EASTERN
WISCONSIN THROUGH THE MID-MORNING HOURS.  BUT WITH DAYTIME
HEATING...MIXING SHOULD TAP INTO THE VERY DRY AIR ABOVE THE
INVERSION WHICH SHOULD LEAD TO RAPID CLEARING EARLY THIS AFTERNOON.
THE EXCEPTION WILL LIKELY BE THE LAKESHORE WHERE NNE WINDS WILL KEEP
LAKE CLOUDS AROUND THROUGH LATE AFTERNOON.  HIGHS IN THE UPPER 40S
TO LOWER 50S.

TONIGHT...CANADIAN HIGH PRESSURE WILL BE BUILDING SOUTHWARD INTO THE
CENTRAL GREAT LAKES.  THIS INCOMING AIRMASS WILL BE VERY DRY...WITH
PWATS UNDER A QUARTER OF AN INCH.  WITH CLEAR SKIES AND LIGHT
WINDS...SHOULD HAVE NEARLY IDEAL RADIATIVE COOLING CONDITIONS.
DROPPED LOW TEMPERATURES BELOW THE COLDEST GUIDANCE.  LOWS IN THE
LOWER 20S WILL BE POSSIBLE ACROSS N-C WISCONSIN.  MAINLY MID 20S TO
LOW 30S EVERYWHERE ELSE.

WEDNESDAY...HIGH PRESSURE WILL REMAIN OVER THE REGION.  A FRONTAL
BOUNDARY WILL MOVE INTO THE NORTHERN MISSISSIPPI VALLEY IN THE
AFTERNOON BUT WILL BE TOO FAR WEST FOR ANY IMPACT ON OUR SENSIBLE
WEATHER.  SO SHOULD SEE ANOTHER DAY OF PLENTY OF SUNSHINE.  LOW
INVERSION HEIGHTS WILL PREVENT MUCH MIXING.  SO EXPECT SEASONABLE
TEMPS IN THE LOWER 50S.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 315 AM CDT TUE OCT 21 2014

UPPER RIDGE OVER WISCONSIN AND ILLINOIS GETS DAMPENED
AND PUSHED TO THE EAST AS AN UPPER TROUGH DROPS TOWARDS WISCONSIN
FROM CENTRAL CANADA WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. AN
ASSOCIATED SURFACE FRONT APPROACHES LATE WEDNESDAY NIGHT AND THEN
MOVES SLOWLY EAST ACROSS THE AREA THURSDAY WHILE A WAVE MOVES TO
THE NORTH ALONG THE FRONT. THE MODELS ARE IN RELATIVELY GOOD
AGREEMENT WITH THE ARRIVAL OF THE SHOWERS BUT THERE ARE
DIFFERENCES IN HOW QUICKLY IT EXITS. MOST PLACES SHOULD GET SOME
SHOWER ACTIVITY THURSDAY AND THURSDAY EVENING BUT AMOUNTS LOOK TO
BE MODEST AND AROUND A QUARTER TO HALF INCH. AFTER THAT UPPER FLOW
BECOMES NORTHWEST WITH DRY WEATHER EXPECTED THROUGH AT LEAST
SUNDAY. RISING UPPER HEIGHTS SHOULD BRING ABOVE NORMAL
TEMPERATURES STARTING ON FRIDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1257 PM CDT TUE OCT 21 2014

MOST OF AREA HAD MVFR CIGS THIS MORNING...BUT DRY AIR MAKING ITS
WAY INTO WISCONSIN FROM THE NORTHEAST WAS CAUSING CLOUDS TO BREAK
UP. BY 1730Z MVFR CIGS WERE MOSTLY CONFINED NORTH CENTRAL AND
PARTS OF CENTRAL WISCONSIN. THERE WERE SOME CIGS NEAR LAKE
MICHIGAN BUT THEY WERE MOSTLY LOW END VFR. EXPECT CLOUDS TO
CONTINUE TO DECREASE THIS AFTERNOON LEAVING CLEAR SKIES FOR THE
OVERNIGHT HOURS. SURFACE HIGH PRESSURE EXTENDING ACROSS WISCONSIN
WILL RESULT IN LIGHT OR CALM WINDS. THE COMBINATION OF CLEAR SKIES
AND LIGHT WINDS COULD PRODUCE PATCHY FOG LATER TONIGHT. 12Z NAM
AND GFS MOS GUIDANCE HAD DEW POINT DEPRESSIONS GENERALLY 4F OR
MORE...BUT WOULD STILL NOT BE SURPRISED IF WE ENDED UP WITH PATCHY
FOG SINCE IT FORMED AT SOME LOCATIONS IN MINNESOTA THAT WERE UNDER
THE HIGH. SHOULD JUST BE HIGH CLOUDS MOVING INTO THE AREA DURING
THE MORNING ON WEDNESDAY.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......MG






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