Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 221725
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1125 AM CST SAT NOV 22 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 352 AM CST SAT NOV 22 2014

STRONG LOW LEVEL JET IS HELPING TO PRODUCE DRIZZLE AND FREEZING
DRIZZLE ACROSS SOUTHEAST WISCONSIN AT 09Z. IT WAS HAVING A HARD
TIME GETTING AS FAR NORTH AS HIGHWAY 151 SO WE DECIDED TO DROP THE
FREEZING RAIN ADVISORY. THERE MAY STILL BE SOME PATCHY DRIZZLE OR
FREEZING DRIZZLE THIS MORNING BUT DO NOT EXPECT A BIG EVENT.
STRONG WARM ADVECTION WILL PRODUCE TEMPERATURES CLOSE TO NORMAL
TODAY.

LOW CLOUDS...DRIZZLE AND FOG EXPECTED TONIGHT AS DEW POINTS IN THE
30S AND 40S OVER THE MISSOURI RIVER VALLEY MOVE NORTHEAST INTO
WISCONSIN. DENSE FOG POSSIBLE WHERE THERE IS DEEP SNOW COVER. LOWS
TONIGHT WILL LIKELY OCCUR IN THE EARLY EVENING WITH RISING
TEMPERATURES OVERNIGHT.

SUNDAY SHOULD BE CLOUDY AND MILD WITH INCREASING CHANCES OF RAIN
AS THE DAY GOES ON. HIGHS IN THE 40S ARE LIKELY IN MOST PLACES
WITH A FEW 50 DEGREE READINGS POSSIBLE.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 352 AM CST SAT NOV 22 2014

THERE IS NO SHORTAGE OF POTENTIAL PITFALLS IN THIS PORTION OF THE
FORECAST MAKING FORECASTER CONFIDENCE RATHER LOW.  CONFIDENCE FALLS
RATHER QUICKLY SUNDAY NIGHT WHEN A DEEP CYCLONE MOVES NORTH OVER THE
CENTRAL GREAT LAKES.  THE GFS/GEM HAVE TRENDED SIGNIFICANTLY
STRONGER WITH THEIR 00Z RUNS...WHILE THE NAM/ECMWF ARE WEAKER
COMPARED TO THE ENSEMBLE GUIDANCE.  A STRONGER SOLUTION IS
POSSIBLE...BUT NOT TO THE EXTENT OF THE GFS. SO WILL GO WITH A GFS
ENSEMBLE MEAN/GEM BLEND. THEREAFTER...THE ECMWF IS MORE IN SYNC
WITH THE GFS ENSEMBLE MEAN BUT THERE IS QUITE A DIFFERENCE BETWEEN
THE ECMWF AND GFS BY 00Z FRIDAY. WILL SIDE WITH THE ECMWF FOR
LATER PERIODS.

SUNDAY NIGHT THROUGH MONDAY NIGHT...LOW PRESSURE WILL DEEPEN RAPIDLY
AS IT LIFTS NORTHWARD SUNDAY NIGHT FROM THE CENTRAL MISSISSIPPI
VALLEY TO NORTHWEST LOWER MICHIGAN. AHEAD OF THE LOW...INCREASING
UPPER DIVERGENCE AND QG FORCING SUPPORTS A LARGE AREA OF
PRECIPITATION SPREADING ACROSS THE REGION DURING THE EVENING.
PLENTY OF WARM AIR AHEAD OF THE SYSTEM...SO PTYPE SHOULD BE RAIN FOR
MUCH OF THE NIGHT UNTIL LATE WHEN COLDER AIR MOVES INTO CENTRAL AND
NORTH-CENTRAL WISCONSIN...AND COULD CHANGE PRECIP TO A MIX OR ALL
SNOW.  COLDER AIR WILL CONTINUE TO WRAP BEHIND THE SYSTEM AND SPREAD
ACROSS THE AREA DURING THE DAY ON MONDAY AS THE LOW LIFTS INTO
ONTARIO.  POTENTIAL IS IMPROVING FOR ACCUMULATING SNOW EVERYWHERE ON
MONDAY...THOUGH ITS STILL RATHER DIFFICULT TO GET A HANDLE ON
POSSIBLE ACCUMS SINCE THE DETAILS REMAIN ELUSIVE.  BUT IF TRENDS
CONTINUE TO SUPPORT A STRONGER SOLUTION...A 1-3 OR 2-4 INCH EVENT IS
POSSIBLE.  BLOWING AND DRIFTING WILL ALSO BECOME AN ISSUE WITH ANY
SNOWFALL SINCE GUSTS 30 TO 35 MPH WILL BE A DISTINCT POSSIBILITY.
THE SNOW WILL GRADUALLY TAPER OFF MONDAY NIGHT EXCEPT WITHIN THE
SNOW BELT WHERE WIND TRAJECTORIES WILL BE FAVORABLE FOR GOOD
ACCUMULATIONS.  WILL SHOW THE HIGHEST SNOW AMOUNTS THERE WHICH COULD
SURPASS WARNING CRITERIA SINCE FAVORABLE WIND TRAJECTORIES COULD
OCCUR FOR 12-18 HOURS.

REST OF THE FORECAST...ANY LINGERING SNOW WITHIN THE SNOW BELT OR
NORTHEAST WISCONSIN WILL EXIT TUESDAY MORNING AS THE LARGE CYCLONE
CONTINUES TO MOVE AWAY FROM THE REGION AND SURFACE RIDGE AXIS BUILDS
IN.  THE NEXT CHANCE OF SNOW WILL OCCUR WEDNESDAY INTO WEDNESDAY
NIGHT WHEN THE NEXT CLIPPER DROPS INTO THE REGION.  BEHIND THE
CLIPPER A 1035-1040MB ARCTIC HIGH WILL MOVE INTO THE REGION...WHICH WILL
BRING ANOTHER ROUND OF VERY COLD TEMPS AND LAKE EFFECT TO THE SNOW
BELTS THROUGH THURSDAY. THE COLD BLAST COULD BE SHORT-LIVED AS
RETURN FLOW RAMPS UP FRIDAY INTO EARLY NEXT WEEKEND.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1124 AM CST SAT NOV 22 2014

ADVERSE FLYING CONDITIONS ARE EXPECTED TNGT INTO SUNDAY AS LOW
CIGS AND LOW VSBYS TO PREVAIL. A WRMFNT IS EXPECTED TO LIFT NORTH
THRU WI TNGT AND BRING EVEN WARMER...MORE MOIST AIR INTO THE
REGION. THIS INCOMING MOIST AIR...COMBINED WITH MELTING SNOW WL
ALLOW FOR WIDESPREAD FOG TO DEVELOP. SOME OF THIS FOG IS FCST TO
BECOME LOCALLY DENSE LATE TNGT INTO SUNDAY MORNING. LIFR/IFR
CONDITIONS ARE EXPECTED WITH THE THICKER FOG OVER THE HIGHER SNOW
PACK. CONDITIONS WL NOT IMPROVE MUCH IF AT ALL ON SUNDAY AS AN
AREA OF LOW PRESSURE LIFTS NE INTO THE MID-MS VALLEY AND A CDFNT
MOVES EAST TOWARD WI IN THE AFTERNOON. RAIN IS FCST TO OVERSPREAD
THE REGION AND HELP TO KEEP AT BEST IFR CONDITIONS IN PLAY THRU
THE DAY.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......MPC
AVIATION.......AK





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