Area Forecast Discussion
Issued by NWS Green Bay, WI

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394
FXUS63 KGRB 070444
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1044 PM CST SAT FEB 6 2016

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 243 PM CST SAT FEB 6 2016

A CLIPPER SYSTEM HEADING FOR THE AREA IS THE MAIN CONCERN IN THE
SHORT TERM. WATER VAPOR SATELLITE IMAGERY SHOWED A MID LEVEL
TROUGH MOVING FROM ROCKIES INTO THE NORTHERN PLAINS TODAY. THIS
FEATURE IS EXPECTED TO CONTINUE INTO THE GREAT LAKES REGION AS A
RIDGE OVER WESTERN NOAM AMPLIFIES...AND A 500MB LOW IS FORECAST
TO DEVELOP BY THE TIME THE TROUGH REACHES CENTRAL WISCONSIN 00Z
MONDAY. AT THE SAME TIME...A SURFACE LOW MOVING INTO THE CANADIAN
PLAINS TODAY...WILL MAKE ITS WAY TO UPPER MICHIGAN. HAVE AT LEAST
A SLIGHT CHANCE FOR SNOW TONIGHT INTO SUNDAY IN WARM ADVECTION
AHEAD OF THE APPROACHING SURFACE SYSTEM. 12Z GFS AND 12Z NAM BUFKIT
TIME/HEIGHT PLOTS FOR LOCATIONS ACROSS THE FORECAST AREA GENERALLY
SHOWED PRECIPITATION TYPE AS SNOW THROUGH 00Z MONDAY...SO HAVE
NOT INCLUDED ANY FREEZING PRECIPITATION OR MIX THOUGH IT CANNOT BE
RULED OUT. SNOW TOTALS TONIGHT SHOULD RANGE FROM AROUND AN INCH
IN FAR NORTHERN WISCONSIN...TO A DUSTING OR NOTHING AT ALL IN
PARTS OF CENTRAL AND EAST CENTRAL WISCONSIN. A MINOR ADDITIONAL
ACCUMULATION IS FORECAST FOR SUNDAY ON THE BACK SIDE OF THE
DEPARTING SURFACE SYSTEM.

SOUTHWEST FLOW IS EXPECTED TO KEEP TEMPERATURES FROM DROPPING
MUCH...IF AT ALL TONIGHT...SO LOWS WILL OCCUR EARLY. INCREASING
WINDS ON SUNDAY SHOULD ALLOW FOR HIGHS IN THE 30S ACROSS THE
ENTIRE FORECAST AREA.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 243 PM CST SAT FEB 6 2016

HIGHLY AMPLIFIED PATTERN FOR MOST OF THE UPCOMING WORK WEEK WITH
GREAT LAKES REGION DOMINATED BY BROAD AND DEEP TROUGH AND SHARP
UPSTREAM RIDGE OVER THE WESTERN CONUS. AFTER A RELATIVELY WARM
START MONDAY...AVERAGE TEMPERATURES FOR THE REST OF THE WEEK WILL
BE WELL BELOW NORMAL. BEST CHANCE FOR MEASURABLE SNOWFALL WILL BE
DURING THE FIRST HALF OF THE WEEK AS UPPER TROUGH DEEPENS AND
CLOSES OFF OVER THE GREAT LAKES REGION.

BY 00Z MONDAY...CONCENSUS OF MODEL GUIDANCE HAS STACKED SYSTEM
SOMEWHERE OVER UPPER MICHIGAN. ASSOCIATED SURFACE LOW IS THEN
FORECAST TO TRACK SOUTHEAST TO LAKE HURON BY 00Z TUESDAY. AS THIS
SYSTEM MOVES ACROSS THE AREA MONDAY NIGHT INTO TUESDAY...A BROAD
AREA OF DISORGANIZED LIGHT SNOW AND SNOW SHOWER ACTIVITY WILL
OVERSPREAD MOST OF THE FORECAST AREA. DEEP MOISTURE IS LIMITED SO
ONLY LOOKING AT LIGHT SNOWFALL AMOUNTS BETWEEN 06Z MONDAY AND 00Z
TUESDAY...GENERALLY IN THE 1 TO 2 INCH RANGE.

ON MONDAY AFTERNOON SEVERAL OF THE MODELS ARE SUGGESTING THAT AS
THE UPPER SYSTEM PASSES TO THE EAST OF THE STATE...LOWER-LEVEL
WINDS WILL TURN NORTHEAST FOR A BRIEF PERIOD WITH WEAK 850 MB WAA
OCCURING OVER EASTERN WISCONSIN AND FOX VALLEY ROUGHLY BEWTEEN
ABOUT 18Z MONDAY AND 06Z TUESDAY. IN ADDITION...A WEAK IMPULSE
ROTATING AROUND THE UPPER SYSTEM WILL ALSO PROVIDE A LITTLE EXTRA
IMPETUS TOWARD SOMEWHAT MORE FOCUSED AND ORGANIZED ASCENT OVER
EAST CENTRAL WISCONSIN. BOTH THE GFS AND NAM CAPTURE THE ESSENCE
OF THIS AND BOTH SUGEST A SOMEWHAT MORE ORGANIZED BAND OF LIGHT
SNOW TO PERSIST OVER THE FOX VALLEY PERHAPS AS LATE AS 06Z
TUESDAY. DID TRY TO SHOW THIS IN THE GRIDS BY RAISING THE POPS
AND QPF SLIGHTLY IN THIS AREA. WITH INCREASING SNOW RATIOS AND
NORTHWEST WINDS DURING THE AFTERNOON ON MONDAY...MONDAY EVENING
COMMUTE COULD BE NEGATIVELY IMPACTED OVER THE FOX VALLEY. RIGHT
NOW LOOKING AT PERHAPS AN INCH OR SO DURING THIS PERIOD IN CONCERT
WITH BLUSTERY NORTHWEST WINDS.

UPPER LOW AND ASSOCIATED SURFACE REFLECTION DO NOT MAKE TOO MUCH
PROGRESS EASTWARD ON TUEDSAY...WITH MOST MEDIUM RANGE GUIDANCE
HOLDING ONTO SOME LIGHT SNOW OR SNOW SHOWER ACTIVITY FOR OUR
LAKESHORE COUNTIES UNTIL MIDDAY. THIS SEEMED REASONABLE SO MADE NO
CHANGES THERE. MEANWHILE FAVORABLE NORTHERLY FETCH IN THE WAKE
OF THE AFORMENTIONED SYSTEM BECOMES ESTABLISHED MONDAY NIGHT AND
PERSISTS INTO WEDNESDAY FOR THE LAKE SUPERIOR SNOWBELT REGION AND
VILAS COUNTY. GIVEN THE PROLONGED PERIOD OF FAVORABLE FETCH AND
OVERWATER INSTABLITY...WOULD NOT BE SURPRISED TO SEE ADVISORY TYPE
SNOWFALL AMOUNTS FOR NORTHWEST VILAS COUNTY. WILL NEED TO KEEP AN
EYE ON THAT.

NEXT REMOTE SHOT AT SOME SYNOPTIC-TYPE LIGHT SNOW WITH ANY
CLIPPER SYSTEMS APPEARS TO BE AROUND THURSDAY. HOWEVER AT THIS
TIME BOTH THE GFS AND ECMWF SUGGEST PRIMARY FORCING WILL REMAIN
WELL TO THE SOUTHWEST OF THE FORECAST AREA. THUS IT APPEARS THERE
WILL BE LITTLE OPPORTUNITY FOR MEASURABLE SNOWFALL FROM MIDWEEK
THROUGH THE REMAINDER OF THE EXTENDED. HOWEVER CAN CERTAINLY COUNT
ON MUCH COLDER AIR TO DOMINATE THE ENTIRE WESTERN GREAT LAKES
REGION GIVEN HIGHLY AMPLIFIED PATTERN AND PERSISTENT NORTHWEST
FLOW. INITIALLY...POCKET OF COLDEST AIR WILL LIKELY BE DRIVEN
SOUTHWARD MAINLY TO THE WEST OF THE FORECAST AREA MONDAY
NIGHT...WITH LAKE MODIFIED AIR HANGING ON OVER EASTERN WISCONSIN.
THEREAFTER...AXIS OF COLDEST AIR SHOULD BEGIN TO SPILL INTO THE
FORECAST AREA AS SURFACE HIGH PRESSURE EDGES EAST. AT THIS TIME
THE COLDEST MORNINGS WOULD MOST LIKELY BE ON WEDNESDAY AND
THURSDAY. WOULD EXPECT MOST OF THE FORECAST AREA TO BE BELOW ZERO
EXCEPT FOR RIGHT ALONG THE LAKE MICHIGAN SHORELINE THURSDAY
MORNING.

OVERALL UPPER PATTERN DOES NOT CHANGE APPRECIABLY INTO THE
WEEKEND WITH GEFS AND ECMWF SUGGESTING ANOTHER REINFORCING SHOT OF
ARCTIC AIR SATURDAY AS BROAD UPPER TROUGH CONTINUES TO DOMINATE
THE EASTERN CONUS.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1038 PM CST SAT FEB 6 2016

VFR CIGS ARE EXPECTED TO PREVAIL TONIGHT...WITH BRIEF FORAYS INTO
MVFR AS LIGHT SNOW IMPACTS THE TAF SITES FROM AN APPROACHING
CLIPPER SYSTEM THROUGH SUNDAY MORNING. AT THIS POINT THERE IS
ENOUGH CONFIDENCE TO PUT A TEMPO GROUP ACROSS ALL OF THE TAF SITES
FOR THIS. MODELS CONTINUE TO HINT AT SOLID MVFR/IFR CONDITIONS ON
SUNDAY BEHIND THIS CLIPPER...HOWEVER UPSTREAM OBSERVATIONS DO NOT
BEAR THIS OUT SO WILL CONTINUE TO BE MORE OPTIMISTIC WITH THIS SET
OF TAFS. ANOTHER ROUND OF SNOW IS EXPECTED ACROSS THE TAF SITES
SUNDAY EVENING...THEREFORE WILL PLACE A PROB30 GROUP ACROSS THE
WESTERN TAF SITES WITH THIS SECOND SHORTWAVE.
&&

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

$$

SHORT TERM.....MG
LONG TERM......ESB
AVIATION.......KURIMSKI



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