Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 282033
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
233 PM CST WED JAN 28 2015

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 232 PM CST WED JAN 28 2015

PLENTY TO DEAL WITH OVER THE NEXT 12 TO 18 HOURS AS A MODEST
SYSTEM MOVES ACROSS THE REGION AND BRINGS THE POTENTIAL FOR A
MIXED PCPN EVENT TO NE WI. MAIN FCST ISSUE ARE TRYING TO DETERMINE
THE PCPN TYPE AND THEN EXTENT OF ANY ICING THAT WOULD WARRANT A
HEADLINE.

THE 20Z MSAS SFC ANALYSIS INDICATED A PAIR OF WEAK LOW PRES AREAS
OVER THE NRN PLAINS CONNECTED BY A CDFNT THAT EXTENDED SWD INTO
THE SRN PLAINS. HI PRES WAS SITUATED OVER THE ERN GREAT LAKES. A
BROAD SOUTHERLY WIND BETWEEN THESE SYSTEMS BROUGHT MILD AIR INTO
WI WITH ABOVE NORMAL READINGS FOR LATE JANUARY. VSBL SATL IMAGERY
SHOWED PLENTY OF MID/HI CLOUDS OVER NE WI AS THE LOW CLOUDS FROM
THIS MORNING HAD MAINLY DISSIPATED.

AFTER A QUIET START TO THE NGT...FCST TO BECOME QUITE COMPLICATED
FROM LATE EVENING FORWARD AS THE SFC CDFNT/MID-LEVEL SHORTWAVE
TROF PUSH ACROSS WI. THE BIG PROBLEM IS A LACK OF SATURATION IN
THE MID-LEVELS...THUS A LACK OF ICE BEING INTRODUCED AND LEADING
TO SUPERCOOLED WATER DROPS REACHING TOWARD THE SFC. THERE IS ALSO
A DRY WEDGE OF AIR FCST BY THE MODELS AROUND 7H THAT HAS TO BE
OVERCOME. BASED ON THE NEW DATA...EXPECT TO SEE FREEZING DRIZZLE
BEING THE PRIMARY FCST TYPE BEFORE GRADUALLY CHANGING OVER TO ALL
SNOW LATE TNGT BEHIND THE CDFNT AS CAA TAKES OVER. NOT CONFIDENT
ENUF ABOUT QPF AMOUNTS TO ISSUE A HEADLINE AT THIS TIME...THUS WL
ISSUE A SPS STATING THE POTENTIAL FOR SLICK ROADS FOR THE MORNING
COMMUTE. TEMPS SHOULD NOT DROP OFF MUCH TNGT AS WAA CONTS TO PUSH
INTO WI AHEAD OF THE CDFNT. LOOK FOR MINS TO MAINLY BE IN THE MID
TO UPR 20S.

FREEZING DRIZZLE/LIGHT SNOW TO LINGER INTO THU MORNING UNTIL THE
SHORTWAVE TROF DEPARTS THE AREA. THE BIGGER CONCERN FOR THU WL BE
THE LAKE EFFECT POTENTIAL ACROSS N-CNTRL WI AS CAA SENDS 8H TEMPS
DOWN TO ALMOST -20C OVER WRN LAKE SUPERIOR AND TRAJS BECOME
FAVORABLE. THE ONLY REAL NEGATIVE LOOKS TO BE A LOW-LEVEL
INVERSION WHICH WOULD LIMIT SNOW ACCUMULATIONS. HAVE RAISED POPS
TO LIKELY FOR NW SECTIONS OF VILAS CNTY...BUT KEPT ACCUMULATIONS
LESS THAN AN INCH FOR NOW. MAX TEMPS TO STILL BE REASONABLY MILD
(MAINLY DUE TO THE WARM START TO THE DAY) WITH READINGS IN THE UPR
20S NORTH...MID 30S E-CNTRL. THESE MAX TEMPS COULD TOP OUT AROUND
MIDDAY BEFORE SLOWLY FALLING IN THE AFTERNOON AS THE COLDER AIR
SETTLES IN OVER THE REGION.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 232 PM CST WED JAN 28 2015

LAKE EFFECT SNOW SHOWERS ARE LIKELY ACROSS NORTH CENTRAL WI
THURSDAY NIGHT...WITH DELTA T/S AROUND 20...FAVORABLE NNW
TRAJECTORIES...AND LOW LEVEL MOISTURE IN PLACE. RAISED POPS OVER
FAR NORTH CENTRAL WI AND INCREASED SNOW TOTALS SLIGHTLY...HOWEVER
ACCUMULATIONS SHOULD REMAIN UNDER AN INCH FOR MOST LOCATIONS. ANY
LAKE EFFECT ACTIVITY WILL DIMINISH FRIDAY MORNING AS WINDS BECOME
MORE WESTERLY...KEEPING ANY SNOW SHOWERS OVER UPPER MICHIGAN.
OTHERWISE...DRY CONDITIONS ARE EXPECTED THURSDAY NIGHT AND FRIDAY
AS HIGH PRESSURE SLIDES OVER THE REGION.

A WEAK CLIPPER SYSTEM WILL PUSH ACROSS THE NORTHERN GREAT LAKES
FRIDAY NIGHT...HOWEVER MOST OF THE SNOW SHOULD STAY NORTH OF
STATE...CLOSER TO THE MAIN SHORTWAVE ENERGY. HOWEVER...CANNOT RULE
OUT SOME FLURRIES ACROSS MUCH OF THE AREA...SO WILL MENTION A
SMALL CHANCE OF LIGHT SNOW ACROSS THE AREA...WITH LITTLE TO NO
ACCUMULATIONS. WINDS BECOME NW BEHIND THE CLIPPER...TRIGGERING
ANOTHER SHOT AT LAKE EFFECT SNOW SATURDAY NIGHT INTO SUNDAY.

ATTENTION THEN TURNS TO THE SYSTEM FOR THE WEEKEND. IT WAS LOOKING
LIKE A GOOD CHANCE FOR SOME KIND OF STORM TO DEVELOP/MOVE ACROSS
THE OHIO VALLEY AND BRING ACCUMULATING SOUTH TO AT LEAST SOUTHERN
WI SATURDAY NIGHT INTO SUNDAY. 12Z ECMWF COMPLETELY JUMPED SHIP AND
NOW SHOWS A MORE PROGRESSIVE SYSTEM WITH LITTLE TO NO SNOW FOR WI.
THIS IDEA IS SUPPORTED BY THE GFS...ALTHOUGH IT BRINGS SOME LIGHT
SNOW TO THE SOUTHERN HALF OF WI. GEM IS STILL ON BOARD WITH A MORE
WRAPPED UP SYSTEM AND DEEPER UPPER TROUGH DIGGING ACROSS THE OHIO
VALLEY. THIS WOULD BRING MORE SIGNIFICANT SNOWFALL TO THE STATE...
AND LINGER THE SNOW INTO MONDAY MORNING. WILL LET THE MODELS TRY
TO GET ON THE SAME PAGE...AND CONTINUE WITH CHANCE POPS ACROSS
THE SOUTHERN HALF OF THE CWA...CLOSER TO WHATEVER SYSTEM
MATERIALIZES...AND CONFINE THE POPS TO SUNDAY. SOME LAKE EFFECT
ACTIVITY IS AGAIN POSSIBLE LATE IN THE WEEKEND AND INTO NEXT WEEK.
OTHERWISE...DRY CONDITIONS ARE EXPECTED AS HIGH PRESSURE BUILDS
IN. NEXT CHANCE FOR PRECIP WILL BE LATE MONDAY INTO TUESDAY AS A
WEAK SYSTEM CROSSES THE GREAT LAKES.

SATURDAY LOOKS TO BE THE WARMEST DAY OF THE EXTENDED...AS MUCH
COLDER AIR WILL BE USHERED INTO THE REGION BEHIND THE SYSTEMS ON
SUNDAY/MONDAY AND NEXT WEEK. HIGHS ON SUNDAY AND MONDAY WILL RANGE
FROM THE UPPER SINGLE DIGITS TO MIDDLE TEENS...WITH LOWS BELOW
ZERO ACROSS CENTRAL AND NORTH CENTRAL WI SUNDAY NIGHT AND MONDAY
NIGHT.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1138 AM CST WED JAN 28 2015

SURGE OF WAA BRINGING MID/HI CLOUD DECK ACROSS NE WI THIS
AFTERNOON. IFR/LOW MVFR CIG STRATUS DECK MAY BREAK FOR A BRIEF
TIME THIS AFTERNOON INTO THE EARLY EVENING...BUT EXPECT CIGS TO
GRADUALLY DROP TOWARD IFR CONDITIONS LATER TONIGHT AS A CDFNT
MOVES SE ACROSS WI. PCPN CHCS TO GO UP TNGT AS THE FNT APPROACHES
AND FCST SNDNGS INDICATE A GOOD POTENTIAL FOR FREEZING DRIZZLE TO
OCCUR BEFORE CHANGING TO ALL SNOW AS THE COLUMN SATURATES. CIGS
SHOULD GRADUALLY IMPROVE TO MVFR CONDITIONS THU MORNING AND
EVENTUALLY VFR CONDITIONS THU AFTERNOON AS HI PRES BEGINS TO BUILD
INTO THE REGION.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......BERSCH
AVIATION.......AK





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