Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 160554
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1154 PM CST MON DEC 15 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 310 PM CST MON DEC 15 2014

MAIN FCST ISSUE WILL BE PRECIPITATION TIMING AND CHANGE OVER.

MILD AND MOIST AIR REMAINS IN PLACE OVER THE AREA. FOG AND
DRIZZLE CONTINUED TO PLAGUE THE STATE TODAY. FOG WILL CONTINUE
INTO TONIGHT AHEAD OF PRECIPITATION AND COLDER AIR ARRIVING THIS
EVENING INTO OVERNIGHT. FOG SHOULD FINALLY COMES TO AN END FOR
ALL LOCATIONS TUESDAY MORNING.

LOW PRESSURE DRIFTED TOWARDS THE GREAT LAKES OUT OF THE SOUTHERN
PLAINS THIS AFTERNOON. SYSTEM HAD BEEN FAIRLY PROGRESSIVE THE
PAST FEW DAYS SO FAR AS IT MOVED INTO IOWA...HOWEVER THE LOW
SHOULD BEGIN TO WEAKEN HENCE FORTH AS IT BECOMING VERTICALLY
STACKED AND LACKS ANY UPPER LEVEL SUPPORT. RADAR RETURNS WITH THIS
SYSTEM SO FAR HAVE BEEN UNIMPRESSIVE...WITH ONLY LIGHT PRECIP
ACCUMULATIONS REPORTED AND VSBYS AROUND 2 TO 3 MILES. IN
GENERAL...GIVEN THE STRUCTURE OF THIS SYSTEM AND THE GENERAL
OVERALL TRENDS...NOT MUCH TO GET EXCITED ABOUT WITH THIS BOUT OF
RAIN. MODELS CONFIRM THIS AND ARE IN GOOD AGREEMENT OF LIGHT RAIN
CONTINUING EARLY TONIGHT.

COLDER AIR WILL STREAM IN BEHIND THE LOW AS WINDS TURN NORTHWEST
TONIGHT AND CAUSE A CHANGE OVER FROM RAIN TO SNOW. THIS CHANGE
OVER SHOULD BEGIN IN THE FAR NORTHWOODS AFTER MIDNIGHT...AND
SLOWLY PROGRESS SOUTH AND EAST THROUGH THE NIGHT. THE LAST PLACE
TO SEE THE CHANGE TO SNOW FLAKES WILL BE THE LAKESHORE...WHICH
SHOULD OCCUR SOMETIME LATE TUESDAY MORNING. SLOWED DOWN THE TIMING
OF THE CHANGE OVER FROM NW TO SE SLIGHTLY AS WE LOST MOST OF OUR
SNOW COVER THE PAST FEW DAYS AND MODEL GUIDANCE CAME IN A BIT
WARMER MONDAY NIGHT AND TUESDAY. IT MAY TAKE A LITTLE LONGER TO
CHANGE OVER THAN PREVIOUSLY FORECASTED.

BUMPED UP SNOW TOTALS SLIGHTLY OVER THE FAR NORTHEAST CORNER.
MODELS SHOW A CORRIDOR OF DECENT FORCING AS THE LOW PRESSURE
SYSTEM SLIDES INTO LOWER MICHIGAN TUESDAY MORNING. THIS SHOULD
OCCUR AS THE RAIN IS CHANGING TO SNOW AND AS WINDS TURN MORE
EAST TO NORTHEAST. NOT A LOT OF SNOW IS EXPECTED...BUT WILL SEE
MORE THAN A TRACE TUESDAY MORNING IN THIS AREA.

THE GOOD NEWS IS THE TRANSITION FROM RAIN TO SNOW SHOULD BE
CLEAN...WITH LITTLE IF ANY SLEET. FORECAST SOUNDINGS ACROSS ALL
THE MODELS SHOW THIS RAPID CHANGE OVER...AND CONFIRMATION IS ALSO
SEEN ON SREF SLEET AND PRECIP TYPE PROBABILITY CHARTS. AS FAR AS
RAIN TO SNOW TYPES OF EVENTS GO...THIS ONE SHOULD BE FAIRLY
STRAIGHT FORWARD WITH FEW HEADACHES.

ONCE PRECIP CHANGES OVER THROUGH OUT THE CWA BY NOON
TUESDAY...LIGHT SNOW WILL CONTINUE BEFORE SLOWLY TAPERING OFF
FROM WEST TO EAST LATE IN THE AFTERNOON. AROUND AN INCH OF NEW
SNOW IS EXPECTED FOR MOST OF NORTHERN PORTIONS OF THE CWA....WITH
LESSER AMOUNTS AS YOU HEAD SOUTH. THE ONLY LOCATION THAT WILL SEE
MORE IS VILAS WHERE SNOW WILL BE THE MAIN PRECIP TYPE AFTER
MIDNIGHT...AND N-NW WINDS ON TUESDAY OVER LAKE SUPERIOR COULD
CREATE SOME LAKE ENHANCEMENT.

BUMPED HIGHS AND LOWS UP A DEGREE OR TWO PER MODEL GUIDANCE
TRENDS...AND DUE TO LACK OF SNOW COVER IN MANY LOCATIONS.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 310 PM CST MON DEC 15 2014

THE AREA REMAINS CAUGHT IN SPLIT FLOW...WHICH WILL CONTINUE THROUGH
NEXT WEEKEND. OUR ATTENTION BOUNCES FROM ONE STREAM TO ANOTHER
WITH A NORTHERN STREAM LOW EXITING THE GREAT LAKES WEDNESDAY. A
SOUTHERN STREAM TROUGH WILL THEN PASS TO OUR SOUTH LATE THIS WEEK
WITH RELATIVELY LITTLE CONSEQUENCE FOR OUR AREA. SOME MINOR LAKE
EFFECT SNOW IN THE WAKE OF THE EXITING LOW...PRIMARILY ON
WEDNESDAY...WILL BE THE ONLY REAL PRECIPITATION OF NOTE UNTIL
NEXT WEEK. OUR MILD TEMPS WILL COME TO AN END...BUT WILL ONLY
FALL TO TEMPERATURES CONSIDERED SEASONABLE FOR THE NEXT SEVERAL
DAYS.

AS THE LOW MOVES OUT OF THE REGION TUESDAY NIGHT...THERE WILL BE
LAKE EFFECT SNOW IN NORTH CENTRAL WISCONSIN. COLD AIR ADVECTION AT
850 ABOVE LAKE SUPERIOR WILL RESULT IN TEMPERATURES RELATIVE TO
THE LAKE SURFACE SUPPORTIVE OF ACCUMULATING SNOW. HOWEVER...A
RELATIVELY LOW INVERSION AND SOME DISAGREEMENT AMONG THE MODELS AS
TO HOW FAVORABLE WIND TRAJECTORIES TRULY WILL BE FOR SNOW IN
WISCONSIN GENERATE SOME UNCERTAINTY IN PRECISELY HOW THE EVENT
WILL UNFOLD. IT SEEMS SAFE TO SAY THAT VILAS COUNTY WILL SEE SOME
LIGHT ACCUMULATION...AN INCH OR TWO THROUGH WEDNESDAY...WHILE AN
ADDITIONAL DUSTING OF SNOW OR FLURRIES IS MORE LIKELY TO THE SOUTH
AND EAST. LOWS TUESDAY NIGHT WILL FALL INTO THE TEENS AND LOWER
20S. WARMING ON WEDNESDAY WILL BE LIMITED...ONLY ENOUGH FOR THE
ENTIRE AREA TO REACH INTO THE 20S.

AS THIS LOW LEAVES THE PICTURE...CANADIAN HIGH PRESSURE BUILDS
INTO THE MIDWEST. THIS WILL BEGIN TO PUSH DRIER AIR INTO THE STATE
WEDNESDAY NIGHT...BRINGING ANY LINGERING SNOW SHOWERS AND FLURRIES
TO A GRADUAL END. LOWS OVERNIGHT WILL AGAIN SETTLE IN THE TEENS
FOR THE MOST PART. AS THE HIGH TAKES COMMAND SKIES
WILL...BRIEFLY...BREAK ON THURSDAY AND FRIDAY. THIS WILL HELP HIGH
TEMPS RISE INTO THE MIDDLE 20S NORTH AND TO NEAR 30 FURTHER SOUTH.
AT NIGHT...IT WILL ALSO ALLOW OVERNIGHT LOWS TO FALL TO AROUND 10
DEGREES IN FAR NORTH CENTRAL WI...WHILE STAYING CLOSER TO 20 IN
THE FOX VALLEY AND LAKESHORE.

AS THE WEEKEND BEGINS...ATTENTION TURNS TO A LOW IN THE SOUTHERN
STREAM. THERE SEEMS TO BE INCREASING CONSENSUS IN THE GUIDANCE
THAT THE TRACK OF THIS LOW WILL BE TOO FAR SOUTH TO
SIGNIFICANTLY IMPACT OUR NORTHEASTERN CORNER OF THE STATE WHERE
HIGH PRESSURE WILL CONTINUE TO REIGN. THE GFS HAS A TRACK ON THE
NORTHERN EDGE OF THE ENVELOPE...AND THAT HAS DRIFTED FAR ENOUGH
SOUTH THAT PRECIPITATION DOES NOT LOOK TO BE A FACTOR EVEN FOR
SOUTHERN WISCONSIN AS IT HAD SUGGESTED EARLIER.

FORECAST CONFIDENCE CONTINUES TO DECREASE LATE IN THE WEEKEND AS A
SHORTWAVE IN THE NORTHERN STREAM PASSES A LITTLE TO OUR NORTH
ACROSS SOUTHERN ONTARIO. THERE MAY BE SOME POTENTIAL FOR LIGHT
SNOW...BUT THERE IS NOT A TON OF EXCITEMENT IN THE GUIDANCE. THE
MODELS APPEAR SLIGHTLY MORE IMPRESSED WITH THE FOLLOWING
SHORTWAVE TOWARDS THE MIDWEEK...BUT AT THIS POINT WE ARE BEYOND
THE SCOPE OF THE FORECAST.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1153 PM CST MON DEC 15 2014

EXPECT MAINLY IFR CIGS AND VSBYS...WITH AREAS OF LIFR CONDITIONS.
THERE MAY EVEN BE ISOLATED MVFR AND VFR CONDITIONS FOR A BRIEF
PERIOD AT THE START OF THE TAF VALID PERIOD.

RAIN WAS FALLING ACROSS THE AREA AT 0530Z BUT WINDS SHIFTED TO THE
NORTH ACROSS NORTH CENTRAL WISCONSIN AS A FRONTAL BOUNDARY PUSHED
THROUGH THAT PART OF THE STATE. THE COLD AIR IN NORTHERLY FLOW
WILL BRING A PERIOD OF MIXED RAIN AND SNOW OR EVEN SOME SLEET
BEFORE PRECIPITATION CHANGES TO ALL SNOW. THIS WILL LIKELY OCCUR
ACROSS NORTH CENTRAL WISCONSIN BETWEEN ABOUT 06Z AND 08Z OR 09Z.
THE TRANSITION FROM RAIN TO SNOW SHOULD OCCUR A BIT LATER IN
CENTRAL AND PARTS OF NORTHEAST WISCONSIN...AND NOT UNTIL LATE
MORNING OR EARLY AFTERNOON IN EAST CENTRAL AND FAR NORTHEAST
WISCONSIN. EXPECT THE WINDS TO INCREASE AFTER SHIFTING.

SNOW SHOULD TAPER OFF...WITH VSBYS IMPROVING TO MVFR/VFR AND CIGS
BECOMING MAINLY MVFR...DURING THE AFTERNOON OR EARLY EVENING IN
MOST AREAS BUT LINGERING SYSTEM SNOW AND SOME LAKE EFFECT CAN BE
EXPECTED IN FAR NORTHERN WISCONSIN INTO THE NIGHT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 7 AM CST TUESDAY FOR WIZ022-040-050.
&&

$$

SHORT TERM.....ALLEN
LONG TERM......LUCHS
AVIATION.......MG






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