Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 290824
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
324 AM CDT FRI AUG 29 2014

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 324 AM CDT FRI AUG 29 2014

WHILE A VERY MOIST AIR MASS CONTINUES TO SPREAD NORTHWARD INTO
THE STATE THIS MORNING...HEAVIER CONVECTION CONFINED FROM FAR
WESTERN WISCONSIN TO MINNESOTA AND IOWA STARTING OUT DISORGANIZED
EARLY THIS MORNING. MODELS DID NOT NOT INITIALIZE WELL WITH AREAS
OF CONVECTION AT THE ONSET. THE MAIN CLUSTER OF STORMS OVER IOWA
IS IN A SHORT WAVE TROF WITH SOME MID LEVEL CONVERGENCE AS PER
700 Q VECTOR PROGS. HOWEVER CONVECTION ALONG THE WARM FRONT FROM
SOUTHERN MINNESOTA INTO FAR WEST CENTRAL WISCONSIN ALSO DEVELOPED
BUT STAYING WELL WEST OF THE AREA AS OF 08Z. BUT HEAVY RAIN
POTENTIAL STILL POSSIBLE THIS MORNING OVER THE STATE...BUT JUST
DELAYED AND LIKELY CONFINED TO WESTERN WI. AIR MASS WAS ALSO
STABLE OVER EASTERN WISCONSIN EARLY THIS MORNING SO WILL CONTINUE
TO DELAY THE THUNDER MENTION.

PROGS IN SOME AGREEMENT WITH KEEPING MORE COVERAGE OF CONVECTION
ACROSS THE NORTH NEAR THE H850 WARM FRONT TODAY BUT DIMINISH
TREND BRIEFLY OVER CENTRAL AND EAST CENTRAL WISCONSIN. BUT CAPE
IS ON THE INCREASE AS PER FORECAST SOUNDINGS OVER CENTRAL AND EAST
CENTRAL WISCONSIN TODAY SOUTH OF THE 850 FRONT WARM FRONT. SO THE
POTENTIAL OF HEAVY RAINFALL WITH SLOW MOVING STORMS STILL
CONTINUES...ESPECIALLY ALONG THE SURFACE WARM FRONT...BUT PLENTY
OF QUESTIONS AS TO WHERE THIS FRONT WILL BE POSITIONED.

CONVECTION LIKELY TO INCREASE FROM THE WEST THIS AFTERNOON AND
CONTINUE INTO TONIGHT BEFORE DECLINING FROM WEST TO EAST LATER
SATURDAY. THE PRIMARY WEATHER FEATURE WILL BE THE DEEP MID LEVEL
TROUGH SWINGING OVER THE STATE...WITH A SUBTLE ASSOCIATED SURFACE
LOW. SOME UPPER JET SUPPORT MAY AID WITH THE LIFT BUT PROGS
BEGINNING TO DIVERT FAVORABLE SUPPORT AREAS.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 324 AM CDT FRI AUG 29 2014

THE MAIN FOCUS IN THIS PORTION OF THE FORECAST NOW SHIFTS TO THE
SUNDAY NIGHT AND MONDAY PERIOD.  THE GEM AND GFS ARE QUICKER WITH
THE FRONTAL PASSAGE THAN THE ECMWF...BUT THE ECMWF HAS MORE SUPPORT
FROM THE GFS ENSEMBLE MEAN.  WILL STICK WITH THE ECMWF FOR THIS
PERIOD...AND A GENERAL BLEND SHOULD WORK THEREAFTER.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...LOW PRESSURE WILL REMAIN
CENTERED OVER FAR NORTHEAST WISCONSIN EARLY SATURDAY EVENING.  EVEN
THOUGH MOST OF THE SHOWER AND THUNDERSTORM ACTIVITY WILL HAVE PASSED
TO THE EAST BY THIS TIME...WILL NEED TO KEEP A CHANCE OF SHOWERS
OVER NORTHEAST WISCONSIN UNTIL THE LOW EXITS.  HIGH PRESSURE THEN
BUILDS IN OVERNIGHT.  IF CLEARING WERE TO OCCUR...LIGHT WINDS AND
RECENT RAINFALL WOULD ALMOST CERTAINLY LEAD TO THE DEVELOPMENT OF
FOG.  WILL LEAVE A MENTION IN THE FORECAST.  THE HIGH PRESSURE
QUICKLY MOVES TO THE EAST ON SUNDAY IN RESPONSE TO THE LEADING EDGE
OF THE WESTERN NOAM TROUGH MOVING INTO THE NORTHERN MISSISSIPPI
VALLEY.  TOO MUCH DRY AIR SHOULD PREVENT PRECIP FROM MOVING INTO THE
AREA THOUGH.  WILL RAISE MAX TEMPS SEVERAL DEGREES.  THEN A
SHORTWAVE WILL ROUND THE BASE OF THE TROUGH AND LIFT NE INTO WESTERN
WISCONSIN LATE SUNDAY NIGHT.  AHEAD OF A COLD FRONT...WHICH WILL
ALSO CROSS THE MISSISSIPPI RIVER LATE SUNDAY NIGHT...A 40 TO 50 KT
LLJ WILL TRANSPORT DEEP MOISTURE INTO NORTH-CENTRAL WISCONSIN AFTER
MIDNIGHT.  ELEVATED CAPES CONTINUE TO LOOK RATHER MARGINAL FOR
SEVERE WEATHER...BUT ANY STORMS WOULD HAVE POTENTIAL TO TRANSPORT
THE STRONGER WINDS ALOFT TO THE SURFACE.  WILL INCREASE PRECIP
CHANCES OVER NORTH-CENTRAL WISCONSIN.

REST OF THE FORECAST...THE FRONT WILL MOVE ACROSS NORTH-CENTRAL
WISCONSIN MONDAY MORNING AND NORTHEAST WISCONSIN MONDAY AFTERNOON.
SHOULD HAVE SUFFICIENT FORCING AND MOISTURE FOR SHOWERS AND STORMS
TO MOVE FROM WEST TO EAST ACROSS THE AREA OVER THE COURSE OF THE
DAY.  SEVERE POSSIBILITIES SHOULD REMAIN MARGINAL UNLESS THE FRONT
SLOWS DOWN AND ALLOWS NORTHEAST WISCONSIN TO DESTABILIZE.  THIS
LOOKS RATHER UNLIKELY SINCE PRECIP SHOULD BE ARRIVING DURING THE
MORNING HOURS.  AS THE FRONT EXITS BY EARLY MONDAY
EVENING...CLEARING SHOULD OCCUR THROUGH THE NIGHT.  THE MODELS WERE
HINTING AT THE POSSIBILITY OF SPOTTY SHOWERS FROM A WEAK WAVE MONDAY
NIGHT INTO TUESDAY...BUT CANNOT FIND MUCH SUPPORT FOR THAT FROM THIS
MODEL CYCLE.  TEMPERATURES WILL BE MODERATING BEHIND THE FRONT BY
MIDWEEK...WITH THE CHANCE OF STORMS INCREASING BY NEXT THURSDAY.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1113 PM CDT THU AUG 28 2014

SCATTERED SHOWERS WILL BECOME MORE NUMEROUS OVERNIGHT AS LOW LEVEL
JET CONTINUES TO ADVECT MOISTURE NORTHWARD FROM THE PLAINS. CIGS
SHOULD CONTINUE TO GRADUALLY LOWER TO MVFR AND IFR IN HEAVIER
SHOWER ACTIVITY. PRECIPITATION THUS FAR HAS BEEN LESS WIDESPREAD
AND WEAKER THAN PREVIOUSLY FORECAST. AS LOW LEVEL JET CONTINUES TO
STRENGTHEN...PRECIPITATION AREA WILL CONTINUE TO EXPAND AND
INCREASE IN INTENSITY SOMEWHAT RESULTING IN MORE WIDESPREAD
MODERATE RAIN AND IFR CIGS ESPECIALLY AT CENTRAL AND NORTHERN WISCONSIN
TAF SITES. BAND OF RAIN WILL CONTINUE TO PUSH NORTHEAST INTO
NORTHERN WISCONSIN AFTER 12Z FRIDAY.

MORE SHOWER AND THUNDERSTORM ACTIVITY IS THEN EXPECTED TO
REDEVELOP OVER MUCH OF THE FORECAST AREA FRIDAY AFTERNOON...AMOUNT
OF THUNDERSTORM ACTIVITY WILL DEPEND SOMEWHAT ON AMOUNT SUNSHINE
THAT CAN BE REALIZED DURING THE AFTERNOON. REGARDLESS...EXPECT
GENERALLY MVFR CIGS WITH AREAS OF IFR CIGS IN HEAVIER
PRECIPITATION.
&&

.HYDROLOGY...
ISSUED AT 324 AM CDT FRI AUG 29 2014

GETTING A SLOW START TO THE HEAVY RAIN THIS MORNING
OVER THE FORECAST AREA. MOST WIDESPREAD INTENSE CONVECTION
REMAINING OUT TO THE WEST OVER SOUTHEAST MINNESOTA INTO IOWA.
CONVECTION OVER SOUTHEAST MINNESOTA NEAR THE 850 FRONT...PWATS
NEAR 1.80 AND CLIMBING...AND ALSO IN A MID LEVEL CONVERGENCE
REGION WHICH EXTENDS SOUTH INTO IOWA. UP TO 1.50 INCHES OF
RAINFALL IN ABOUT AN HOUR OBSERVED EARLY THIS MORNING OVER
SOUTHEAST MINNESOTA IN THIS BAND OF CONVECTION. THESE DYNAMICS ARE
EXPECTED TO DRIFT INTO PARTS OF WEST CENTRAL WISCONSIN THIS
MORNING AND MAY WORK OR DEVELOP INTO PARTS OF CENTRAL WISCONSIN
THIS MORNING BEFORE DRIFTING NORTHEASTWARD TODAY. SINCE THE HEAVY
RAINFALL OVERALL HAS HELD OFF THIS MORNING OVER THE AREA...WILL
PLAN ON CONTINUING WITH AN ESF THIS MORNING FOR RIVER RISES THE
NEXT FEW DAYS. MUCH OF THE REGION STILL EXPECTING A SOAKING RAIN
WITH TOTAL AMOUNTS FROM 2 TO 3 INCHES BY THE END OF SATURDAY
AFTERNOON...BUT MOST OF THE RAINFALL FALLING OVER A 36 HOUR
PERIOD...AND NOT DURING A 3 HOUR PERIOD. BUT THIS IS AN AVERAGE
RAINFALL TOTAL...A FEW STORMS MAY PRODUCE LOCALLY HIGHER AMOUNTS
IF PASSING OVER THE SAME AREA. ITS POSSIBLE A SHORT FUSED FLASH
FLOOD OR FLOOD WATCH IS NEEDED LATER TODAY IF THE SURFACE WARM
FRONT LIFTS INTO THE AREA AND BECOMES MORE OF A FOCUS FOR
CONVECTION.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......ESB
HYDROLOGY......TDH






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