Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 201136
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
536 AM CST THU NOV 20 2014

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 401 AM CST THU NOV 20 2014

CYCLONIC COLD FLOW WILL PRODUCE SCATTERED TO BROKEN CLOUDS AND
SNOW FLURRIES TODAY. LAKE EFFECT SNOW SHOWERS OVER UPPER MICHIGAN
MAY DRIFT SOUTH INTO VILAS COUNTY TODAY AS MODELS SUGGEST THAT
WINDS WILL BECOME A LITTLE MORE NORTHWESTERLY. KEPT THE LAKE
EFFECT SNOW ADVISORY FOR NOW. HIGHS TODAY WILL BE AROUND 20
DEGREES BELOW NORMAL WITH WIND CHILLS BELOW ZERO IN MOST PLACES.

SURFACE HIGH OVER THE PLAINS WILL MOVE ACROSS THE AREA TONIGHT.
LOWS SHOULD DROP BELOW ZERO WHERE THERE IS SIGNIFICANT SNOW COVER.
LOWS WILL STAY IN THE SINGLE NUMBERS NEAR THE LAKE AND BAY.

SOUTHERLY FLOW RETURNS FRIDAY WITH RAPID WARMING AT 850 AND 925MB.
SURFACE TEMPERATURES WILL LIKELY NOT WARM AS QUICKLY DUE TO SNOW
COVERED GROUND AND TEMPERATURE INVERSION. HIGHS WILL BE AROUND 15
DEGREES BELOW NORMAL.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 401 AM CST THU NOV 20 2014

THE MEDIUM RANGE MODELS ARE GETTING INTO BETTER AGREEMENT WITH THE
DEEP CYCLONE MOVING NORTH ACROSS THE REGION LATE IN THE WEEKEND.
THERE ARE STILL MODEST TIMING/TRACK DIFFERENCES.  WILL BLEND THE GFS
AND ECMWF.  THEREAFTER...LARGE DIFFERENCES DEVELOP IN THE GUIDANCE
BY THE MIDDLE OF NEXT WEEK AND WILL ROLL WITH THE SUPERBLEND
GUIDANCE.

FRIDAY NIGHT THROUGH SATURDAY NIGHT...SOUTHERLY WINDS AROUND A HIGH
PRESSURE SYSTEM CENTERED OVER THE MID-ATLANTIC STATES WILL ADVECT
LOW LEVEL MOISTURE NORTHWARD ACROSS WISCONSIN SATURDAY NIGHT.
THOUGH THE MOISTURE DOES NOT LOOK QUITE AS DEEP AS MODELS SHOWED IT
LAST NIGHT...IT STILL LOOKS SUFFICIENT FOR A CHANCE OF FREEZING
DRIZZLE OR LIGHT SNOW IF SEEDER FEEDER PROCESSES FROM A MID DECK
COME INTO PLAY.  THE THREAT OF FREEZING DRIZZLE WILL CARRY OVER INTO
SATURDAY MORNING THOUGH MOISTURE PROFILES DO NOT LOOK QUITE AS
SATURATED BY 18Z.  EVEN IF SURFACE TEMPERATURES RISE ABOVE
FREEZING...THE COLD GROUND MAY STILL SUPPORT FREEZING DRIZZLE FOR A
PERIOD...ESPECIALLY OVER N-C WISCONSIN.  THERE IS POTENTIAL FOR THE
THREAT OF FREEZING DRIZZLE TO END SOMETIME SATURDAY AFTERNOON WHEN
SATURATION HEIGHTS FALL TO ONLY 900MB.  WILL LOWER PRECIP CHANCES
SAT AFTERNOON.  AS THE FLOW BACKS SATURDAY NIGHT...ANOTHER PUSH OF
LOW LEVEL MOISTURE WILL ARRIVE LATE SOUTH OF ROUTE 29.  WILL DROP
PRECIP CHANCES ACROSS THE NORTH AND CONFINE THEM TO THIS AREA.  NO
SIGNIFICANT CHANGES TO TEMPS.

REST OF THE FORECAST...LOW PRESSURE WILL RAPIDLY STRENGTHEN AS IT
LIFTS NORTH INTO THE SOUTHWEST GREAT LAKES BY SUNDAY EVENING.  AHEAD
OF THE LOW...STRONG FORCING AND PWATS APPROACHING AN INCH WILL BRING
A SWATH OF PRECIP SUNDAY AFTERNOON THROUGH SUNDAY NIGHT.  PLENTY OF
WARM AIR AHEAD OF THE SYSTEM WILL MAKE PTYPE MOSTLY RAIN UNTIL COLD
AIR WRAPS AROUND THE SYSTEM ON THE SOUTHWEST FLANK LATE SUNDAY NIGHT
WHEN A CHANGE OVER TO SNOW COULD OCCUR OVER CENTRAL AND
NORTH-CENTRAL WISCONSIN.  A CHANGE OVER TO MIX AND SNOW SHOULD
CONTINUE TO TAKE PLACE ON MONDAY FROM SOUTHWEST TO NORTHEAST WITH
SOME ACCUMULATIONS LIKELY OVER CENTRAL AND NORTH-CENTRAL WISCONSIN.
MINOR ACCUMULATIONS WILL OCCUR ELSEWHERE ON MONDAY NIGHT WITH THE
LOW STILL SPINNING OVER EASTERN LAKE SUPERIOR...BUT COULD LOOK AT
SIGNIFICANT ACCUMS IN THE SNOW BELTS OF N-C WISCONSIN DUE TO LAKE
EFFECT.  THE CHANCE OF SNOW WILL CONTINUE ON TUESDAY WITH
TEMPERATURES FALLING BACK INTO THE 20S.  CONTINUED COLD ON
WEDNESDAY.  THEN LOOKING FOR THE NEXT PRECIP CHANCES TO ARRIVE ON
THURSDAY.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 536 AM CST THU NOV 20 2014

COLD AIR ALOFT WILL MAKE FOR SCATTERED TO BROKEN CLOUDS WITH BASES
BETWEEN 2500 AND 3500 FEET IN MOST PLACES. SCATTERED SNOW SHOWERS
ARE ALSO POSSIBLE. LAKE EFFECT SNOW OVER UPPER MICHIGAN COULD DRIFT
SOUTH TO D25/LNL/EGV/ARV TODAY AND PRODUCE BRIEF IFR. SKIES SHOULD
CLEAR ACROSS THE AREA TONIGHT WITH VFR WEATHER FRIDAY.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL NOON CST TODAY FOR WIZ005.
&&

$$

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





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