Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 021118
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
618 AM CDT WED SEP 2 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 254 AM CDT WED SEP 2 2015

ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS HAS LED TO THE
FORMATION OF FOG EARLY THIS MORNING ACROSS MUCH OF CENTRAL AND
NORTH CENTRAL WISCONSIN. ALTHOUGH AREAS TO THE EAST ARE NOT AS
FOGGY...VISIBILITIES COULD STILL DROP DURING THE MORNING HOURS.
THE FOG IS EXPECTED TO DISSIPATE LATER THIS MORNING SHORTLY AFTER
SUNRISE.

THE MAIN FORECAST CONCERN TODAY AND TONIGHT WILL BE A THUNDERSTORM
COMPLEX ACROSS SOUTHWESTERN MINNESOTA SLOWLY TRACKING EAST
ASSOCIATED WITH A MID LEVEL TROUGH WHICH CAN CLEARLY BE SEEN ON
WATER VAPOR IMAGERY. THIS COMPLEX IS SCHEDULED TO TRACK THROUGH
THE CWA DURING THE LATE AFTERNOON AND EARLY EVENING HOURS PER THE
HI- RES MODEL RUNS. IN ADDITION THERE ARE ALSO SIGNS OF
DEVELOPMENT AHEAD OF THIS MAIN SYSTEM ACROSS NORTHERN WISCONSIN
LATER THIS MORNING AND EARLY THIS AFTERNOON AHEAD OF A THETA-E
SURGE WHICH EVENTUALLY CONGEALS INTO ONE LARGE COMPLEX RIGHT OVER
NORTHEAST WISCONSIN. THIS LARGER COMPLEX IS SCHEDULED TO SLOWLY
TRACK THROUGH THE AREA OVERNIGHT AND INTO THURSDAY
MORNING...DUMPING COPIOUS AMOUNTS OF RAIN GIVEN THE COPIOUS PWAT
VALUES APPROACHING 2 INCHES...LONG SKINNY CAPE PROFILES...AND VERY
WEAK WIND FIELD OWING TO A SLOW MOVING SYSTEM. GIVEN THE MODEL
SOLUTIONS WILL RAISE POPS TO LIKELY ACROSS THE FORECAST
AREA...FOCUSING ON THE LATE AFTERNOON AND EARLY EVENING WHEN THE
COMPLEX IS MOSTLY LIKELY TO TRACK THROUGH THE AREA.

DESPITE DECENT FORECAST MUCAPE VALUES OF 2000 TO 3000
J/KG...SEVERE WEATHER POTENTIAL IS LOW GIVEN THE VERY WEAK WIND
FIELD IN PLACE WITH NOT MUCH IN THE WAY OF SHEAR. THE MAIN SEVERE
THREAT LOOKS TO BE A FEW PULSE STORMS THAT COULD APPROACH SEVERE
LIMITS...WITH A WET MICROBURST PRODUCING SOME ISOLATED WIND DAMAGE
BEING THE MAIN THREAT IF SEVERE WEATHER DOES OCCUR. HENCE THE
MARGINAL RISK FOR SEVERE WEATHER ACROSS NORTHERN WISCONSIN THIS
AFTERNOON AND EVENING PER THE SPC DAY 1 OUTLOOK. THE MARGINAL RISK
FOR SEVERE WEATHER ASIDE...FLOODING APPEARS TO BE THE PRIMARY
CONCERN ACROSS THE AREA TODAY AND TONIGHT GIVEN THE ABUNDANT
MOISTURE AND SLOW MOVING NATURE OF THE STORMS.

THE FOG FORECAST OVERNIGHT WILL BE TRICKY TO SAY THE LEAST AS THIS
COMPLEX COULD KEEP AREAS RELATIVELY FOG FREE...OR FOGGIER GIVEN
THE INCREASED LOW LEVEL MOISTURE AFFORDED BY THE THUNDERSTORMS. AT
THIS POINT WILL KEEP PATCHY FOG IN THE FORECAST OVERNIGHT.

TEMPERATURES DURING THIS PERIOD WILL BE TENUOUS AT BEST...AS HIGHS
WILL BE DEPENDENT ON WHEN THUNDERSTORMS DEVELOP OR MOVE IN FROM
THE WEST AND HOW MUCH TEMPERATURES CAN SOAR BEFORE THIS HAPPENS.
CURRENT THINKING IS THE AREA SHOULD STILL GET INTO THE 80S GIVEN
THE VERY WARM AIRMASS IN PLACE...HOWEVER THE THREAT OF REACHING 90
LOOKS LOWER TODAY GIVEN THE CLOUDS RAPIDLY APPROACHING FROM THE
WEST. LOWS TONIGHT COULD BE TRICKY AS WELL GIVEN THE
THUNDERSTORM...HOWEVER LOWS IN THE 60S ARE GENERALLY EXPECTED PER
THE LAST FEW NIGHTS. TEMPERATURES ON THURSDAY SHOULD BE A FEW
DEGREES COOLER...WITH HIGHS IN THE LOWER TO MIDDLE 80S...AS THIS
COMPLEX SLOWLY TRACKS EAST AND THE EXPANSIVE CLOUD SHIELD ALSO
EXITS THE REGION.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 254 AM CDT WED SEP 2 2015

ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK...
BEFORE A SIGNIFICANT COOL DOWN IS EXPECTED BY THE MIDDLE OR END
OF NEXT WEEK (ECMWF).

INTERESTING SCENARIO SETTING UP THURSDAY NIGHT WHICH WILL LINGER
INTO FRIDAY MORNING. THE GFS/WRF/CANADIAN DEPICT SOME PRECIPITATION
DEVELOPING OR CONTINUING THURSDAY NIGHT...IN RESPONSE TO WEAK
850MB WARM ADVECTION AND WEAK 850MB WINDS OVER RUNNING WEAK
BOUNDARY DRAPED ACROSS SOUTH OF THE AREA. THE ECMWF DID NOT SHOW
THIS SCENARIO AND THE OFFICES TO THE SOUTH FOLLOWED THIS MODEL.
HAVE A HARD TIME GOING DRY WITH SEVERAL MODELS PRODUCING
PRECIPITATION...THUS KEPT 20 TO 30 PERCENT CHANCES OF SHOWERS AND
STORMS. ANY PRECIPITATION WOULD AT LEAST LINGER INTO FRIDAY
MORNING IF IT DEVELOPS.

OTHERWISE WARM AND HUMID CONDITIONS WILL PREVAIL THROUGH THE
WEEKEND. SMALL CHANCE OF SHOWERS AND STORMS SATURDAY...BUT
BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE DURING THE
SUNDAY INTO MONDAY TIME FRAME AS A WEAK COLD FRONT MOVES ACROSS
THE REGION. WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED AT THIS
TIME...ALTHOUGH LOCALLY HEAVY IS POSSIBLE. MUCH COOLER WEATHER
SHOULD RETURN TO THE AREA BY THE MIDDLE TO END OF NEXT WEEK.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 618 AM CDT WED SEP 2 2015

AREAS OF DENSE FOG ARE EXPECTED THIS MORNING...WITH IFR/MVFR VSBYS
PERSISTING THROUGH 14Z. A MID-LEVEL SHORTWAVE TROF OVER THE UPPER
MISSISSIPPI VALLEY WILL BRING A THUNDERSTORM COMPLEX THROUGH
WISCONSIN TODAY AS IT SLOWLY TRACKS EAST THROUGH THE WESTERN GREAT
LAKES. AS THE SHORTWAVE DISTURBANCE INTERACTS WITH MORE
INSTABILITY DURING THE DAY...ADDITIONAL STORMS COULD FORM AHEAD OF
THE MAIN SYSTEM ACCOMPANIED BY MVFR CIGS/VSBYS.

THE VERY MOIST AND MODERATELY UNSTABLE ATMOSPHERE...IN CONCERT
WITH RELATIVELY LIGHT WINDS ALOFT...WOULD FAVOR SLOW MOVING AND
MORE DISORGANIZED SUB-SEVERE PULSE-TYPE STORMS CAPABLE OF
PRODUCING LOCALLY HEAVY DOWNPOURS.

SOME FOG IS EXPECTED ACROSS THE WESTERN TAF SITES TONIGHT AS THE
MAIN SYSTEM HEADS EAST WITH ABUNDANT MOISTURE AND LIGHT WINDS
ALLOWING FOR SOME PATCHY DENSE FOG.
&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......ECKBERG
AVIATION.......KURIMSKI



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