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000
FXUS63 KGRB 161809
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
109 PM CDT WED APR 16 2014

UPDATED AVIATION PORTION FOR 18Z 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 18Z TAF ISSUANCE
ISSUED AT 109 PM CDT WED APR 16 2014

WINTER STORM TO MOVE FROM THE NRN PLAINS NEWD INTO WI
TNGT AND EVENTUALLY TOWARD LAKE SUPERIOR ON THU. HVY SNOW TO FALL
ACROSS NRN WI WITH THE RHI TAF SITE PRETTY MUCH EITHER IFR OR LIFR
TNGT INTO THU MORNING. CNTRL AND E-CNTRL WI COULD ACTUALLY SEE A
LULL IN THE PCPN THRU THE EVENING HOURS BEFORE PCPN BEGINS TO PICK
UP LATER TNGT AS THE SFC LOW APPROACHES. LOOK FOR CIGS/VSBYS TO GO
FROM VFR THIS EVENING TO MVFR CONDITIONS DURING THE OVRNGT HOURS.
WHILE MVFR CONDITIONS SHOULD PERSIST INTO THU MORNING...CIGS COULD
BRIEFLY DROP DOWN TO IFR CONDITIONS THU MORNING. IMPROVING
CONDITIONS ARE THEN EXPECTED FOR THU AFTERNOON AS THE SFC LOW
BEGINS TO PULL AWAY.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 1 PM CDT THURSDAY FOR WIZ005-010>012.

WINTER WEATHER ADVISORY UNTIL 1 PM CDT THURSDAY FOR WIZ013-018-
019-021.

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

$$

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