Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 161153
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
653 AM CDT WED APR 16 2014

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 419 AM CDT WED APR 16 2014

WINTER WEATHER HEADLINES FOR TODAY THROUGH EARLY THURSDAY ARE THE
MAIN FCST CONCERN.

A BAND OF LIGHT SNOW WAS DEVELOPING FROM CENTRAL MN INTO WEST CENTRAL
WI EARLY THIS MORNING...AND SHOULD WORK ITS WAY INTO CENTRAL WI WITHIN
THE NEXT HOUR OR SO. THE SNOW BAND WAS THE RESULT OF INCREASING WAA/
ISENT LIFT AND MID-LEVEL FRONTOGENETIC FORCING. IT WILL LIKELY TAKE
ANOTHER 3-5 HOURS BEFORE THE SNOW OVERSPREADS NC/FAR NE WI...AS VERY
DRY AIR REMAINS IN PLACE THERE...WITH SFC DEW POINTS IN THE SINGLE
DIGITS.

IMPRESSIVE DYNAMIC FORCING WILL IMPACT THE REGION TODAY AND TONIGHT...
WITH WAA ASSOCIATED WITH A 40-55 KT LLJ...STG UPPER LEVEL DIVG WITH
THE RRQ OF A JET TODAY AND A COUPLED JET STRUCTURE TONIGHT...AND
DEEP FRONTOGENETIC FORCING. DESPITE THE STRONG FORCING...MODEL
TRENDS SUPPORTED LOWERING QPF AND SNOWFALL AMOUNTS A LITTLE BIT
TODAY AND EARLY TONIGHT...INITIALLY DUE TO THE DRY CONDITIONS AT
ONSET...THEN IN ASSOCIATION WITH A LINGERING POCKET OF DRY AIR IN
THE 900-800 MB LAYER THIS AFTERNOON AND EARLY EVENING. EVEN
SO...PERIODS OF MODERATE SNOW SHOULD OCCUR OVER MAINLY NC WI
THROUGH THIS EVENING. HAVE SHIFTED THE RAIN/SNOW LINE A LITTLE
FARTHER SOUTH THAN THE PREVIOUS FCST...AS LOW-LEVEL THICKNESSES AND
WET BULB TEMPS ONLY SUPPORT A MIX SOUTH OF AN RRL-MNM LINE THIS
AFTERNOON/EVENING.

THE HEAVIEST SNOW OF THE EVENT IS LIKELY TO OCCUR OVER NC/FAR NE
WI LATE TONIGHT...AS A STRONG NEGATIVELY-TILTED S/W TROF SWINGS
THROUGH NORTHERN WI...AND THE SFC-H8 CIRCULATIONS MOVE THROUGH
THE REGION. HAVE INCREASED SNOWFALL AMOUNTS CONSIDERABLY DURING
THE 06Z-12Z/THU PERIOD...AND LINGERED SOME ACCUMS INTO EARLY
THURSDAY. HAVE MAINTAINED THE WINTER STORM WARNING OVER FAR
NORTHERN WI...WHERE TOTAL SNOW ACCUMS OF 8 TO 13 INCHES ARE
EXPECTED. HAVE ADDED NORTHERN OCONTO COUNTY INTO THE WINTER
WEATHER ADVISORY...AS TOTALS OF 4 TO 6 INCHES ARE ANTICIPATED
THERE.

THE ADVISORY OVER MARATHON COUNTY IS A BIT PROBLEMATIC...AS
SNOW IS EXPECTED DURING THE BEGINNING AND END OF THE EVENT...
WITH A PERIOD OF MIXED RAIN AND SNOW IN THE MIDDLE. THE TWO PERIODS
OF SNOW MAY RESULT IN TOTAL ACCUMS OF 2 TO 4 INCHES...BUT THAT IS
OVER A 24 HOUR PERIOD. DESPITE MARGINAL CONDITIONS...HAVE OPTED
TO KEEP THE ADVISORY GOING...ESPECIALLY SINCE A BAND OF SNOW WILL
LIKELY IMPACT THE RUSH HOUR THIS MORNING. THE DAY SHIFT CAN DECIDE
IF THE HEADLINE SHOULD BE CONTINUED AFTER THE INITIAL BAND OF SNOW
MOVES THROUGH...OR SNOW BECOMES MIXED WITH RAIN.

AS THE SNOW TAPERS OFF THURSDAY MORNING...THERE MAY BE A BRIEF
PERIOD OF DRIZZLE OR FREEZING DRIZZLE AS THE DRY SLOT ARRIVES.
EXPECT MAINLY DRY CONDITIONS TO PREVAIL BY AFTERNOON.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR MAX/MIN
TEMPS THE NEXT TWO DAYS.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 419 AM CDT WED APR 16 2014

NO SIGNIFICANT CHANGES TO THE EXPECTED UPPER AIR PATTERN THROUGH
EARLY NEXT WEEK AS IT TRANSITIONS TO MORE OF A DEAMPLIFIED AND
PROGRESSIVE PATTERN.  MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT
THROUGH EARLY THIS WEEKEND BEFORE BREAKING DOWN WITH INCOMING
PACIFIC ENERGY.  PREFER THE ECMWF THROUGH 12Z SUNDAY AND WILL LET
THE ALLBLEND HANDLE THE REST.

THURSDAY NIGHT THROUGH FRIDAY NIGHT...A WEAK COLD FRONT WILL SLOWLY
MOVE EAST ACROSS THE CENTRAL GREAT LAKES THURSDAY NIGHT WHILE HIGH
PRESSURE SLIDES INTO WESTERN WISCONSIN.  MID AND HIGH CLOUDS
TRAILING BEHIND THE COLD FRONT WILL PROVIDE FOR PARTLY TO MOSTLY
CLOUDY CONDITIONS THURSDAY EVENING...THEN SHOULD SEE PARTIAL
CLEARING TAKE PLACE OVERNIGHT.  THE SURFACE HIGH WILL DRIFT ACROSS
THE AREA ON FRIDAY...BUT WEAK SHORTWAVE ENERGY WILL PROVIDE AT LEAST
SCT CLOUD COVER IF NOT BROKEN AT TIMES.  THINKING THAT A DRY WEDGE
IN THE MID-LEVELS WILL KEEP THE AREA DRY THOUGH.  HIGHS REMAINING IN
THE UPPER 30S TO MIDDLE 40S.  HIGH PRESSURE WILL REMAIN OVER THE
AREA ON FRIDAY NIGHT.  COULD SEE MID AND HIGH CLOUDS INCREASE LATE
AHEAD OF THE NEXT STORM SYSTEM.  LOWS MAINLY IN THE 20S.

REST OF THE FORECAST...RETURN FLOW WILL DEVELOP ON SATURDAY AS THE
SURFACE HIGH MOVES INTO THE EASTERN GREAT LAKES BY LATE IN THE DAY.
INCREASING ISENTROPIC ASCENT WITHIN THE 700MB THETAE AXIS COULD
BRING SOME SHOWERS INTO NORTH-CENTRAL WISCONSIN...MAINLY DURING
THE AFTERNOON THOUGH TIMING IS STILL A LITTLE SUSPECT.  BETTER
CHANCES OF RAIN WILL ARRIVE SATURDAY NIGHT INTO SUNDAY WHEN DEEPER
MOISTURE FROM THE SOUTHERN PLAINS IS TAPPED.  THOUGH FORCING WILL BE
WEAKENING OVER THIS TIME...PWATS APPROACHING AN INCH COULD LEAD TO
SOME DECENT RAINS.  SOME LIGHT RAIN COULD LINGER INTO MONDAY OVER
EASTERN WISCONSIN IF REINFORCING SHORTWAVE ENERGY CAUSES THE FRONT
TO HANG BACK.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 643 AM CDT WED APR 16 2014

A BAND OF LIGHT SNOW WAS ATTEMPTING TO ORGANIZE OVER THE FORECAST
AREA EARLY THIS MORNING...BUT DRY AIR WAS SLOWING ITS PROGRESS. A
STEADY SNOW WILL DEVELOP LATER THIS MORNING OVER NC/FAR NE WI...
CONTINUE THIS AFTERNOON THROUGH TONIGHT...THEN END THURSDAY MORNING.
THE SNOW WILL BE HEAVY AT TIMES...ESPECIALLY LATE TONIGHT. FARTHER
SOUTH...LIGHT SNOW WILL EVENTUALLY MIX WITH OR CHANGE OVER TO RAIN
FOR A WHILE THIS AFTERNOON AND EVENING...THEN TRANSITION BACK TO
SNOW WEST AND NORTH OF THE FOX VALLEY OVERNIGHT. CONDITIONS WILL
DETERIORATE TO MVFR/IFR ONCE PCPN DEVELOPS...ALTHOUGH LIFR/VLIFR
CONDITIONS ARE EXPECTED WITH HEAVY SNOW OVER NC/FAR NE WI LATER
TONIGHT.

LLWS IS EXPECTED TO DEVELOP THIS AFTERNOON...AND PERSIST THROUGH
MOST OF THE NIGHT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 10 AM THIS MORNING TO 10 AM CDT
THURSDAY FOR WIZ005-010>012.

WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 AM CDT
THURSDAY FOR WIZ013-018-019-021.

WINTER WEATHER ADVISORY UNTIL 10 AM CDT THURSDAY FOR WIZ030.
&&

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......MPC
AVIATION.......KIECKBUSCH






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