Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 041042
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
442 AM CST THU FEB 4 2016

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 241 AM CST THU FEB 4 2016

STEEP LOW LEVEL LAPSE RATES WITH 700-800 MB SNOW GROWTH REGION
PASSING OVER EAST CENTRAL WISCONSIN EARLY THIS MORNING PRODUCED
A MINOR ACCUMULATION OF FLURRIES AND SNOW SHOWERS. AVAILABLE
MOISTURE MAY BE FOCUSING ALONG A SUBTLE BOUNDARY PASSING
OVER...GRB WINDS SHIFTED NW TO WSW EARLY THIS MORNING.  FORECAST
SOUNDINGS SUGGESTS A CONTINUED DRYING FROM THE MID TO LOWER LAYERS
SO ANTICIPATED THIS REGION OF LIGHT PRECIPITATION WILL BE
DEPARTING OR DIMINISHING TOWARD DAY BREAK.

CLOUDS HANGING TOUGH ACROSS THE AREA EARLY THIS MORNING INCLUDING
OVER CENTRAL AND NORTH CENTRAL WISCONSIN AS A WEAK SURFACE RIDGE
BUILDS INTO THE AREA. ANY CLEARING EARLY THIS MORNING WILL ALLOW
TEMPS TO PLUMMET DUE TO THE FRESH SNOW COVER.

FOCUS THEN TURNS TO A WEAK CLIPPER SYSTEM TO DROP OVER THE AREA
MAINLY THIS AFTERNOON AND EVENING. PROGS SUGGESTS A LIGHT
ACCUMULATION OF SNOW...SO WILL UP THE POPS A LITTLE TO ACCOUNT FOR
THE LIGHT ACCUMULATION. THE CLEARING TREND WITH LOW TEMPS AGAIN
AN ISSUE LATER TONIGHT AS THIS CLIPPER SYSTEM DEPARTS AND ANOTHER
WEAK RIDGE SLIDES OVER. CLOUDS WILL BE ON THE INCREASE AGAIN LATER
FRIDAY AS ANOTHER WEAK SYSTEM APPROACHES THE AREA IN THE NORTHWEST
FLOW ALOFT.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 241 AM CST THU FEB 4 2016

MODELS CONT TO ADVERTISE A HIGHLY-AMPLIFIED MEAN FLOW CONSISTING
OF A WRN NOAM UPR RDG AND E-CNTRL NOAM UPR TROF BY THE START OF
NEXT WEEK. PRIOR TO THIS AMPLIFICATION...TWO CLIPPER SYSTEMS ARE
FCST TO DROP SE INTO THE GREAT LAKES (FRI NGT INTO SAT AND SUN
INTO MON NGT). THE FIRST CLIPPER WL NOT HAVE A LOT OF MOISTURE AND
IS RELATIVELY WEAK. THE SECOND CLIPPER APPEARS STRONGER...HAVE
BETTER UPR SUPPORT AND MORE MOISTURE AVAILABLE TO BRING A BETTER
CHC OF ACCUMULATING SNOW TO NE WI. TEMPS ARE EXPECTED TO GO ABOVE
NORMAL THIS WEEKEND THRU MON BEFORE DROPPING BELOW NORMAL FROM TUE
ONWARD.

MODELS ARE IN GOOD AGREEMENT WITH THE MOVEMENT OF A WEAK CLIPPER
INTO NRN SECTIONS OF THE GREAT LAKES REGION FRI NGT. A CDFNT AND
SHORTWAVE TROF WL ACCOMPANY THE SFC LOW WITH AN AREA OF LIGHT SNOW
MOVING INTO CNTRL WI FRI EVENING AND ERN WI MAINLY AFTER THE
MIDNGT HOUR. MOISTURE IS LACKING WITH THIS SYSTEM...HOWEVER AROUND
AN INCH OF ACCUMULATION IS POSSIBLE OVER NRN WI WHERE MID-LEVEL
FORCING IS STRONGER. CNTRL/E-CNTRL WI SHOULD ALSO SEE A LITTLE
LIGHT SNOW OR FLURRIES WITH LITTLE ACCUMULATION (ONE-HALF INCH OR
LESS). MIN TEMPS TO RANGE FROM 10 TO 15 ABOVE NORTH...15 TO 20
DEGS SOUTH. VERY SMALL PCPN CHCS MAY LINGER INTO SAT MORNING NORTH
(WINDS VEER W-NW AND MAY BRING A BRIEF LAKE EFFECT SNOW SHWR OR
SOME FLURRIES) OR EAST (CDFNT STILL EXITING THE AREA).
OTHERWISE...SAT LOOKS TO BE A MAINLY DRY DAY AS A WEAK RDG OF HI
PRES PUSHES THRU WI. WE MAY BE ABLE TO SEE A FEW PEEKS OF
SUNSHINE...HOWEVER THIS HI PRES APPEARS TOO WEAK TO SCOUR OUT ALL
THE MOISTURE...THUS MOSTLY CLOUDY SKIES SHOULD PREVAIL. MAX TEMPS
SHOULD BE ABLE TO REACH THE MID 20S N-CNTRL...UPR 20S TO LWR 30S
ELSEWHERE.

CLOUDS WL QUICKLY THICKEN SAT NGT AS THE NEXT CLIPPER SYSTEMS
DROPS SE TOWARD THE SE MANITOBA/NE ND/NW MN VCNTY BY 12Z SUNDAY.
WE COULD SEE THE LEADING EDGE OF LIGHT SNOW ALREADY APPROACH CNTRL
WI LATE SAT NGT AS A CDFNT SWEEPS INTO THE UPR MS VALLEY AND MID-
LVL Q-G FORCING INCREASES INTO WRN WI. MORE CLOUDS TRANSLATES INTO
TEMPS NOT FALLING TOO FAR WITH READINGS IN THE MID TO UPR TEENS
NORTH...LWR 20S SOUTH. THIS CLIPPER IS PROGGED TO MOVE SE INTO THE
WRN GREAT LAKES BY SUNDAY AFTERNOON WITH THE CDFNT ARCING SE THRU
AT LEAST CNTRL WI BY 00Z MON. THERE APPEARS TO BE SUFFICIENT
LIFT...MID-LVL FORCING AND MOISTURE AVAILABLE FOR THIS CLIPPER TO
BRING A GOOD CHC OF LIGHT SNOW TO ALL OF NE WI...ESPECIALLY DURING
THE AFTERNOON HOURS. HAVE RAISED POPS FROM THE PREVIOUS FCST AND
THERE COULD BE A MINOR ACCUMULATION BY SUNSET. MILD TEMPS (MAXES
AROUND 30 NORTH...LWR TO MID 30S SOUTH) COULD HAVE SOME OF THIS
SNOW MELT ON CONTACT...THUS LIMITING ACCUMULATION NUMBERS.

AS THE WRN NOAM UPR RDG STRENGTHENS AND THE E-CNTRL NOAM UPR TROF
DEEPENS EARLY NEXT WEEK...THIS WL CAUSE THE CLIPPER TO ESSENTIALLY
STALL RIGHT OVER THE GREAT LAKES SUNDAY NGT AND MON. THE
COMBINATION OF CYCLONIC FLOW WITH VARIOUS EMBEDDED SHORTWAVES
ROTATING THRU THE UPR TROF...SHOULD KEEP LIGHT SNOW IN OUR FCST.
POPS HAVE BEEN HELD IN THE HI CHC CATEGORY FOR THE TIME BEING...
HOWEVER IF CURRENT MODEL TRENDS HOLD STEADY...POPS WL NEED TO BE
RAISED. IN ADDITION...A TIGHTENING PRESSURE GRADIENT ON THE
BACKSIDE OF THE SFC LOW ON MON COULD CREATE SOME BLOWING/DRIFTING
OF THE SNOW. TOO EARLY YET FOR POTENTIAL ACCUMULATION...BUT THERE
ARE SIGNALS THAT THIS WL BE A SHOVABLE SNOW.

SNOW CHCS WL CONT INTO MON NGT AS THE SFC LOW DRIFTS TOWARD THE
ERN GREAT LAKES AND WEAKENS A BIT AS A NEW SFC LOW MOVES UP THE
ATLANTIC SEABOARD. WE COULD SEE ADDITIONAL MINOR ACCUMULATIONS...
ESPECIALLY ERN WI EVEN AS THE CYCLONIC FLOW WEAKENS. A BIGGER
CONCERN IS N-CNTRL WI FOR LAKE EFFECT SNOWS AS COLDER AIR BEGINS
TO SURGE SWD OVER WRN LAKE SUPERIOR ON N-NW WINDS. DELTA-T VALUES
CLIMB INTO THE LWR TO MID 20S WITH LAKE-INDUCED CAPES > 500
J/KG...SO WL NEED TO WATCH THIS SITUATION CLOSELY IN THE COMING
DAYS. SOME IMPROVEMENT IS EXPECTED BY TUE AS THE SYSTEM SLIDES
FARTHER EAST AND HI PRES BUILDS INTO THE UPR MS VALLEY. WL NEED TO
CONT THE WATCH OVER N-CNTRL WI WHERE LAKE EFFECT SNOW SHWRS SHOULD
STILL BE ONGOING.

NE WI TO BE FIRMLY ENTRENCHED IN A NW FLOW ALOFT TOWARD THE MIDDLE
OF NEXT WEEK AND EXPECT TEMPS TO TURN SHARPLY COLDER STARTING ON
TUE AND CONTINUING INTO WED. EXACTLY HOW COLD WE CAN GET AT NGT WL
DEPEND ON CLOUD COVER AS TEMPS MAY VARY BY 10 TO 15 DEGS BETWEEN
CLOUDY AND CLEAR SKIES. THE HI PRES DOES NOT LOOK OVERLY STRONG...
THUS CLOUDS MAY BE HARD TO GET RID OF. OTHER THAN SOME LINGERING
LIGHT SNOW SHWRS OVER N-CNTRL WI...WED SHOULD BE A DRY DAY WITH
MAX TEMPS A GOOD 10 TO 15 DEGS BELOW NORMAL.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 441 AM CST THU FEB 4 2016

MAINLY VFR CIGS NOTED ACROSS THE REGION EARLY THIS
MORNING WITH SCATTERED MVFR CIGS ACROSS THE FAR NORTH. SCATTERED
SNOW SHOWERS OVER EASTERN WISCONSIN WERE PRODUCE 4-5SM VSBYS EARLY
THIS MORNING. OTHERWISE MAINLY VFR CONDITIONS TODAY BEFORE AN
APPROACHING CLIPPER SYSTEM PRODUCES MVFR CIGS OVER CENTRAL AND
NORTH CENTRAL WISCONSIN THIS AFTERNOON AND THEN EASTERN SECTIONS
THIS EVENING. AREAS OF IFR CIGS WITH MVFR VSBYS DUE TO LIGHT SNOW
ALSO LIKELY DURING THIS PERIOD.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......AK
AVIATION.......TDH



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