Area Forecast Discussion
Issued by NWS Green Bay, WI

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663
FXUS63 KGRB 071059
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
459 AM CST SUN FEB 7 2016

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 332 AM CST SUN FEB 7 2016

A LARGE CLIPPER TYPE SYSTEM WILL DROP INTO THE NORTHERN PLAINS
AND GREAT LAKES REGION TODAY THROUGH MONDAY. MAIN IMPACTS OF WIND
AND BLOWING SNOW WILL BE FELT WEST OF THE AREA TOWARD MINNESOTA
TODAY AND TONIGHT.

FOR THIS REGION...A SURGE OF WARMER AIR IN THE LOWER LAYERS AHEAD
OF THE SYSTEM WILL PRODUCE A LIGHT MIX TODAY. AS SATURATION
OCCURS FROM WEST TO EAST LATE THIS AFTERNOON INTO TONIGHT...THE
MIX WILL TURN TO SNOW AND THE SNOW COVERAGE WILL GRADUALLY SPREAD
EASTWARD AS THE SYSTEM DROPS INTO THE STATE.

ANTICIPATE A PROLONGED PERIOD OF LIGHT SNOW AND FLURRIES WITH THIS
SYSTEM THROUGH MONDAY...WITH A GRADUAL ACCUMULATION. COLDER AIR
BEGINS TO POUR INTO WESTERN WISCONSIN LATE TONIGHT WITH LAKE
EFFECT SNOWS OVER FAR NC WI CLOSE BEHIND WHICH WILL CONTINUE INTO
MONDAY. EXPANDED THE MENTION OF PATCHY BLOWING SNOW EASTWARD OVER
THE AREA MONDAY WITH INCREASING PRESSURE GRADIENT. ISSUED A
WINTER ADVISORY OVER VILAS FOR THE COMBO SNOW AND BLOWING SNOW
FROM THE WIND LATER TONIGHT INTO MONDAY. STARTED THE HEADLINE AT
00Z MONDAY TO MATCH UP WITH DLH AND MQT...BUT ANTICIPATE ADVISORY
CONDITIONS LIKELY TO START LATER EVENING.

TEMPERATURES EXPECTED TO BE ON A DECLINE TONIGHT INTO MONDAY AS
THE COLD FRONT SLIDES OVER.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 332 AM CST SUN FEB 7 2016

HIGHLY-AMPLIFIED MEAN FLOW ACROSS THE CONUS WL CONT INTO THE
MIDDLE OF NEXT WEEK BEFORE GRADUALLY FLATTENING FOR LATER IN THE
WEEK. EVEN AS THIS OCCURS...WE WL MAINTAIN UPR RIDGING OVER THE
WRN CONUS AND UPR TROFFING OVER THE ERN CONUS. NE WI TO STILL BE
UNDER THE INFLUENCE OF A CLIPPER SYSTEM AND ASSOCIATED NEARLY
CLOSED UPR LOW THRU TUE...THEN HAVING TO DEAL WITH AN ARCTIC AIR
INTRUSION FOR THE REST OF THE WEEK. LK EFFECT SNOW SHWRS ACROSS
N-CNTRL WI WL BE A CONCERN WHENEVER TRAJS BECOME FAVORABLE AND
THIS WL BE THE MAIN FCST CHALLENGE FOR MUCH OF THE WEEK.

A PERSISTENT N-NW CYCLONIC FLOW IS FCST FOR MON NGT THRU TUE...
THAT WL CONT TO DRAW COLDER AIR INTO THE GREAT LAKES. 8H TEMPS ARE
EXPECTED TO BE AROUND -16C ON MON NGT AND FALL INTO THE -18C TO
-22C RANGE ON TUE. THIS CYCLONIC FLOW...COUPLED WITH THE PASSAGE
OF SEVERAL SHORTWAVES DROPPING SE INTO THE E-CNTRL CONUS UPR
TROF...SHOULD KEEP AT LEAST A SMALL CHC FOR SNOW SHWRS OVER NE
WI...ESPECIALLY OVER N-CNTRL (LK EFFECT) AND ERN WI (WHERE DEEP
MOISTURE TO EXIST). WHILE MOST LOCATIONS WL SEE ONLY MINOR
ACCUMULATIONS (AN INCH OR LESS)...MAIN CONCERN WL BE N-CNTRL WI
(PRIMARILY VILAS CNTY) AS TRAJS ARE FAVORABLE AND DELTA-T VALUES
RISE INTO THE LWR TO MID 20S BY TUE. MAY NEED TO RAISE POPS OVER
VILAS CNTY UP TO LIKELY WITH A MON NGT/TUE SNOW TOTAL IN THE 2 TO
4 INCH RANGE. TEMPS WL BEGIN THEIR DOWNWARD SLIDE AS THE MODIFIED
ARCTIC AIR GRADUALLY TAKES OVER. LOOK FOR LOWS MON NGT TO BE IN
THE SINGLE DIGITS ABOVE ZERO CNTRL WI...TEENS FOR ERN WI. HI TEMPS
ON TUE TO ONLY BE IN THE TEENS TO AROUND 20 DEGS.

THE SLOW OVERALL EWD MOVEMENT OF THIS SYSTEM WL KEEP THIS CYCLONIC
FLOW OVER THE WRN GREAT LAKES THRU WED...ALBEIT IN A WEAKENING
FASHION. ANTICIPATE ADDITIONAL LK EFFECT SNOW SHWRS TO IMPACT
VILAS CNTY THRU TUE NGT BEFORE EASING IN INTENSITY ON WED AS SOME
DRIER AIR BEGINS TO ADVECT INTO THE REGION FROM HI PRES SITUATED
OVER THE UPR MIDWEST. HAVE AGAIN RAISED POPS FOR VILAS CNTY TUE
NGT TO LIKELY IN THE SNOWBELT WITH PERHAPS ANOTHER INCH OF
ACCUMULATION POSSIBLE. THE REMAINDER OF CNTRL/E-CNTRL WI SHOULD
SEE SKIES GRADUALLY BECOME PARTLY CLOUDY LATE TUE NGT INTO WED
WITH THE PREVAILING NW WINDS CONTINUING TO FEED COLD AIR INTO WI.
MIN TEMPS TUE NGT TO RANGE FROM ZERO TO 5 BELOW CNTRL WI...TO
AROUND 5 ABOVE ZERO NEAR LK MI WITH WIND CHILLS FROM 10 TO 20
BELOW ZERO. MAX TEMPS ON WED SHOULD GENERALLY BE IN THE 10 TO 15
ABOVE ZERO RANGE.

WE FINALLY LOSE THE CYCLONIC FLOW ALTOGETHER BY WED NGT AS THE SFC
HI BUILDS INTO THE WRN GREAT LAKES. IF SKIES CAN CLEAR AND WINDS
DECOUPLE...WED NGT WOULD END UP AS THE COLDEST NGT OF THE EXTENDED
FCST WITH THE TYPCIALLY COLDER SITES PERHAPS APPROACHING DOUBLE
DIGITS BELOW ZERO...WHILE ONLY LAKESIDE AREAS REMAINING ABOVE
ZERO. THU LOOKS TO BE A DRY DAY WITH THE SFC HI IN OUR VCNTY UNDER
PARTLY CLOUDY SKIES. MAX TEMPS TO AGAIN BE IN THE TEENS THROUGHOUT
THE ENTIRE FCST AREA.

LONG RANGE MODELS THEN DIVERGE ON THE HANDLING OF SHORTWAVE ENERGY
RIDING SEWD ALONG A TIGHT BAROCLINIC ZONE DIVIDING MILDER AIR FROM
THE ARCTIC AIR. THE GFS HAS LESS AMPLITUDE WITH THE E-CNTRL UPR
TROF...THUS ALLOWING FOR WARMER AIR TO APPROACH WI ON FRI AND
BRING A CHC FOR LIGHT SNOW TO MOVE THRU THE REGION. THE ECMWF HAS
MORE AMPLITUDE WITH THE UPR TROF...THEREBY KEEPING THE WARMER AIR
WELL TO OUR SOUTH AND WEST AND KEEPING ANY PCPN AWAY FROM WI.
BELIEVE THAT THE GFS IS BEING OVERZEALOUS IN BREAKING DOWN THE
PATTERN TOO QUICKLY AND PREFER TO LEAN THE FCST TOWARD THE ECMWF.
THEREFORE...HAVE KEPT MOST OF NE WI DRY FOR FRI...OTHER THAN
PERHAPS A FEW SNOW SHWRS OVER VILAS CNTY. AN AREA OF HI PRES IS
THEN FCST TO MOVE TOWARD THE GREAT LAKES NEXT SAT AND WL KEEP DRY
CONDITIONS IN PLACE WITH TEMPS REMAINING BELOW NORMAL.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 458 AM CST SUN FEB 7 2016

AN AREA OF IFR CIGS WILL PASS OVER NORTH CENTRAL WISCONSIN
THROUGH MID MORNING...FOLLOWED WITH A PERIOD OF MAINLY VFR CIGS
AHEAD OF CLIPPER SYSTEM DROPPING INTO THE AREA. AS THE SYSTEM
MOVES INTO THE GREAT LAKES REGION...MVFR AND THEN IFR CONDITIONS
WILL SPREAD FROM WEST TO EAST ACROSS THE REGION LATE THIS
AFTERNOON AND TONIGHT. IFR CIGS AND VSBYS DUE TO SNOW SHOWERS WILL
BE MORE NUMEROUS OVER FAR NORTH CENTRAL WI.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
MONDAY FOR WIZ005.
&&

$$

SHORT TERM.....TDH
LONG TERM......KALLAS
AVIATION.......TDH



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