Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 310853
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
353 AM CDT SUN AUG 31 2014

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 352 AM CDT SUN AUG 31 2014

ISOLATED SHOWERS DEPARTED FAR NORTHEAST WISCONSIN EARLY THIS
MORNING AS THE COMPACT VORT CENTER IN THE DEPARTING MID/UPPER
TROUGH SHIFTS NORTHEAST.

FIRST ISSUE THIS MORNING IS THE POTENTIAL OF DENSE FOG AND
POSSIBLE HEADLINE ACROSS THE AREA. SAT IMAGERY SHOWS PLENTY OF
CLOUDS ACROSS THE FORECAST AREA AS THE UPPER TROUGH DEPARTS TO THE
NORTHEAST THIS MORNING. CLOUDS DID CLEAR OUT ACROSS NORTH CENTRAL
WISCONSIN EARLIER THIS MORNING AND FOG DEVELOPED QUICKLY. HOWEVER
AT 08Z...PATCHY STRATUS CLOUDS HAVE SPREAD BACK INTO PARTS OF NORTH
CENTRAL WISCONSIN TO KEEP THE DENSE FOG AT A PATCHY COVERAGE FOR NOW.
STILL ANTICIPATE MORE FOG DEVELOPMENT THIS MORNING WITH THE LIGHT
WINDS UNDER THE RIDGE AXIS AND THE RECENT RAINFALL. WILL CONTINUE
TO MONITOR THIS MORNING BUT WILL LIKELY START OUT WITH AN SPS.

AFTER A PERIOD OF FOG AND LOW CLOUDS THIS MORNING...RETURN WAA
FLOW INCREASES FROM WEST TO EAST TODAY AHEAD OF FAIRLY STRONG
FRONTAL SYSTEM APPROACHING FROM THE NORTHERN PLAINS. FORECAST
SOUNDINGS ARE DRY AT THE MID LEVELS OVER PARTS OF CENTRAL AND
NORTH CENTRAL WISCONSIN BUT SOME STEEPER LAPSES RATES AND CAPE
BEGINNING TO SHOW UP IN THE MID LAYERS OVER CENTRAL AND
NORTH CENTRAL WISCONSIN LATE IN THE DAY. WILL STILL HOLD OFF
CONVECTION MENTION UNTIL THIS EVENING OVER WESTERN AREAS AND
OVERNIGHT FOR THE REST OF THE REGION.

AS FAR AS SEVERE POTENTIAL...MORNING DATA SUGGESTS THE BRUNT OF
THE LLJ DYNAMICS CONFINED TO AREAS TO THE WEST BUT INSTABILITY
DOES BEGIN TO INCREASE BY THIS EVENING OVER THE WESTERN HALF OF
THE STATE. MODELS ARE IN SOME AGREEMENT WITH A COUPLE JET
REGION OF THE UPPER JET SLIDING THROUGH THE EARLY PART OF
MONDAY...WITH THE INCREASING UPPER JET AXIS SLOWLY DROPPING
SOUTHWARD LATER MONDAY. DEEP SHEAR LIKELY ON THE INCREASE AS WELL
AS THE SHORT WAVE TROUGH SLIDES INTO THE STATE. WILL HIGHLIGHT THE
PRIMARY THREATS IN THE MORNING HWO.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 352 AM CDT SUN AUG 31 2014

UPPER LEVEL FLOW ACROSS THE REGION IS EXPECTED TO BE MAINLY ZONAL
THROUGH THE END OF THE FORECAST. SHORT WAVES IN THE WESTERLY FLOW
WILL BRING SEVERAL CHANCES FOR RAIN THROUGH NEXT WEEKEND...BUT
TIMING OF THE SHORT WAVES IS SOMEWHAT PROBLEMATIC. MODELS SHOWED
DIFFERENCES IN TIMING THE EXIT OF PRECIPITATION ON MONDAY
NIGHT...WITH THE 00Z GFS AND 00Z NAM HOLDING ONTO QPF IN EAST
CENTRAL WISCONSIN MONDAY EVENING WHILE THE 00Z ECMWF WAS DRY. HAVE
LEFT SOME SMALL POPS...MAINLY IN THE LAKESHORE COUNTIES...MONDAY
EVENING TO ACCOUNT FOR THE SLOWER SOLUTIONS. MODELS INDICATED SOME
QPF WITH A WEAK SHORT WAVE PASSING THROUGH THE REGION SHORTLY
AFTER THE PREVIOUS SYSTEM EXITS. THERE WERE DIFFERENCES IN THE
EXACT LOCATION AND TIMING OF THIS...SO HAVE SLIGHT CHANCES FOR
SHOWERS TUESDAY AFTERNOON AND NIGHT.

THINGS DO NOT LOOK ANY MORE STRAIGHTFORWARD REGARDING PRECIPITATION
CHANCES LATER IN THE WEEK SO DO NOT MAKE MAJOR CHANGES TO EXTENDED
FORECAST INITIALIZATION GRIDS.

TEMPERATURES ARE EXPECTED TO BE NEAR OR ABOVE NORMAL THROUGH THE
END OF THE WORK WEEK...THEN BACK BELOW NORMAL FOR THE WEEKEND.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1052 PM CDT SAT AUG 30 2014

QUESTIONS WILL BE CIGS AND VSBYS TONIGHT AS WEAK SURFACE HIGH
MOVES IN. SOME BREAKS IN CLOUDS CONTINUE GIVEN LATEST SATELLITE
THOUGH WITH LIGHT WINDS AND PLENTY OF LINGERING LOW LEVEL MOISTURE
EXPECT ANY CLEARING WILL BE REPLACED BY IFR CIGS AND/OR VISBY
CLEARING BY MID DAY SUNDAY. NEXT FRONTAL SYSTEM TO APPROACH THE
ARREA LATE IN THE TAF PERIOD. HAVE INCREASED CLOUDS ONCE
MORE...THOUGH WILL HOLD OFF PCPN TIL AFTER 06Z.
&&

.HYDROLOGY...
ISSUED AT 352 AM CDT SUN AUG 31 2014

FROM THE FRIDAY NIGHT AND SATURDAY RAINFALL
AMOUNTS...SOME STORM SPOTTERS REPORTED SOME SMALL STREAMS AND
CREEKS ROSE TO BANK FULL OVER PARTS OF CENTRAL WISCONSIN...BUT
THE MAIN RIVER STEMS WERE ABLE TO HANDLE THE 2-4 INCHES OF
RAIN...BUT ALSO RISING. WILL HAVE A 24-36 HOUR BREAK BEFORE
ANOTHER ROUND OF HEAVY RAIN PASSES OVER SUNDAY NIGHT INTO MONDAY
WITH A COLD FRONT PASSAGE. SYSTEM APPEARS MORE PROGRESSIVE THAN
THE SLOW SYSTEM THE LAST FEW DAYS...BUT WITH PWATS CLIMBING TO
ABOVE NORMAL LEVELS AGAIN...SOME STORMS MAY PRODUCE LOCALLY HEAVY
RAINFALL. APPEARS A COUPLE OF FEATURES TO FOCUS ON FOR HEAVY
RAIN...THE LLJ WITH THE PLUME OF HIGHER PWATS LATE TONIGHT BUT
APPEARS TO BE FOCUSED OVER MINNESOTA AND PERHAPS FAR WESTERN
WISCONSIN...AND THEN THE UPPER JET SUPPORT LIFTING NORTHEAST OVER
THE STATE MONDAY MORNING AS THE FRONT AND SHORT WAVE TROUGH MOVES
IN. DYNAMICS WOULD SUGGEST THE HEAVIER RAINFALL WILL FALL OVER THE
NORTHWEST HALF OF THE STATE MONDAY MORNING WITH THE REST OF THE
CONVECTION LIKELY MORE PROGRESSIVE.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......MG
AVIATION.......TE
HYDROLOGY......TDH






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