Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 240344
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1044 PM CDT SAT AUG 23 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 259 PM CDT SAT AUG 23 2014

WEAK FORCING WILL CONTINUE TO ACT ON VERY MOIST AIRMASS IN PLACE
OVER THE FORECAST AREA INTO THE EARLY EVENING HOURS. CONVECTIVE
COMPLEX OVER NORTHEAST ILLINOIS LATE THIS AFTERNOON WILL CONTINUE
TO PUSH EAST-SOUTHEAST ALONG WARM FRONT. NORTHERN PERIPHERY OF
THIS COMPLEX AND ASSOCIATED WEAK MID-LEVEL CONVECTIVE LY INDUCED
CIRCULATION WILL CONTINUE TO IMPACT THE SOUTHERN PORTION OF THE
FORECAST AREA INTO THE EARLY EVENING. STRATIFORM PRECIPITATION AREA
WILL CONTINUE TO DRIFT NORTHEAST AND WEAKEN AS IT MOVES TOWARD
THE SOUTHERN THIRD OF LAKE MICHIGAN. MEANWHILE A BIT FURTHER NORTH
OVER PARTS OF EASTCENTRAL AND NORTHEAST WISCONSIN...WEAK
ISENTROPIC LIFT AHEAD OF WEAKENING SHORTWAVE IMPULSE ENTERING
WESTCENTRAL WISCONSIN HAS BEEN ABLE TO GENERATE WIDELY SCATTERED
SHOWER ACTIVITY THROUGHOUT THE AFTERNOON HOURS. THIS ACTIVITY IS
VERY PULSE-LIKE IN NATURE AND SLOW MOVING. WHERE IT DOES
RAIN...DOWNPOURS ARE HEAVY WITH 12Z GRB SOUNDING SHOWING WINDS AOB
2O KNOTS AND DEEP MOISTURE. AS A RESULT WILL NEED TO KEEP
SCATTERED WORDING GOING INTO THE EARLY EVENING. OVERNIGHT SHORT
RANGE GUIDANCE SHOWS WEDGE OF 22-24 C 850 TEMPS SURGING NORTHWARD
ACROSS THE WESTERN PORTION OF WISCONSIN...ESSENTIALLY CAPPING THAT
AREA. FURTHER EAST...CAPPING IS WEAKER. NOCTURNAL LLJ WILL LIKELY
INCREASE SOME OVERNIGHT OVER SOUTHWEST WISCONSIN. WRF ARW DOES
HINT AT SOME LIGHT PRECIPITATION BREAKING OUT ACROSS EASTERN
WISCONSIN TOWARD DAYBREAK SUNDAY. ALTHOUGH CONFIDENCE NOT HIGH THAT THIS
WILL ACTUALLY MATERIALIZE...DECIDED TO KEEP SOME VERY LOW POPS
ACROSS EASTERN WISCONSIN ROUGHLY BETWEEN 09Z AND 13Z SUNDAY.
SOME PATCHY FOG ALSO POSSIBLE AGAIN OVERNIGHT BUT AT THIS TIME
WIDESPREAD DENSE FOG SEEMS UNLIKELY WITH A GREATER POSSIBILITY OF
SEEING LOW STRATUS INSTEAD.

LOOKS LIKE SUNDAY WILL STILL BE MAINLY DRY AS UPPER RIDGE STILL IN
CONTROL OVER THE FORECAST AREA AND LARGE-SCALE FORCING ASSOCIATED
WITH PRIMARY SHORTWAVE OVER THE NORTHERN PLAINS STILL WELL TO THE
WEST. ALSO HARD TO FIND ANY WEAK EMBEDDED SHORTWAVE IMPULSES
WITHIN INCREASING SOUTHWESTERLY UPPER-LEVEL FLOW OVER THE
FORECAST AREA THAT MIGHT HELP TO INITIATE SOME ISOLATED CONVECTION
SUNDAY AFTERNOON. MAX TEMPERATURES ON SUNDAY CHALLENGING AND WILL
BE DEPENDENT ON HOW QUICKLY ANY MORNING FOG/STRATUS CAN ERODE...
AND HOW MUCH CLOUD COVER WILL BE AROUND DURING THE AFTERNOON AS
WARM FRONT APPROACHES THE AREA. OPTED TO STAY ON THE CONSERVATIVE
SIDE AND TONED DOWN MAX TEMPS A DEGREE OR TWO. REGARDLESS...WITH
DEW POINTS AROUND 70...WILL FEEL QUITE UNCOMFORTABLE WITH HEAT
INDICES PERHAPS APPROACHING THE UPPER 90S OVER THE SOUTHWEST
PORTION OF THE FORECAST AREA.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 259 PM CDT SAT AUG 23 2014

LITTLE CHANGE IN THE MEAN FLOW PATTERN ADVERTISED BY THE MODELS.
THIS PERIOD STARTS TRANSITION TO FLATTER PATTERN AS UPPER LOW/TROF
LIFTS OUT OF WEST INTO EASTERN RIDGE POSITION. STRONGER WESTERLY
FLOW EXPECTED ACROSS SOUTHERN CANADA BY MID WEEK.

WARM/MUGGY/UNSETTLED WEATHER EXPECTED THOUGH MONDAY. A COLD FRONT
MOVING THROUGH ON MON WILL GRADUALLY BRING COOLER/LESS HUMID
CONDITIONS TO THE REGION. QUESTIONS IN MODELS INCLUDE HOW FAR SOUTH THE
FRONT WILL MOVE AND THE PATH OF SHORT WAVE MOVING NORTHEAST INTO
THE WESTERN LAKES TUESDAY. CHANCE POPS TO CONTINUE WITH HIGHER
POPS SOUTH. MODIFIED TEMPS TUESDAY WARMING FAR NORTH A BIT WITH
THOUGHTS OF LESS CLOUDS/SHOWERS NORTH CENTRAL.

SEVERE CHANCES LOW THROUGH THIS PERIOD..BEST SHEAR NORTHWEST OF
AREA THROUGH SUNDAY...WHILE BEST INSTABILITY SOUTH WITH FRONT.
WITH SIG MOISTURE LINGERING OVER AREA...AGAIN HEAVY RAIN BIGGEST
CONCERN. SHEAR OVER AREA BETTER TUE...THOUGH UNCERTAINTY OF PCPN
COVERAGE HIGHER.  CAN NOT RULE OUT A FEW STRONGER STORMS.

FURTHER OUT...MODELS TRENDING A BIT FURTHER NORTH AND EAST WITH
COOLER AIR MASS...WHILE POPS REINTRODUCED OVER SOUTH WITH
UNCERTAINTY WITH FRONT AND PASSAGE OF WEAK UPPER TROF TO SOUTH OF
AREA.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1044 PM CDT SAT AUG 23 2014

IFR CONDITIONS WILL LIKELY CONTINUE IN CENTRAL AND
NORTHCENTRAL WISCONSIN THROUGH MID TO LATE MORNING SUNDAY. DRIER
AIR MOVED INTO NORTHEAST AND EAST CENTRAL WISCONSIN DURING THE
EVENING HOURS...AND IT IS UNCERTAIN WHETHER LOW CLOUDS AND FOG
WILL RETURN LATER TONIGHT. THE CURRENT THINKING IS THAT WINDS
WILL DIMINISH AND LOW CLOUDS WILL FORM AGAIN IN THESE AREAS AFTER
AROUND 09Z BUT CONFIDENCE IS LOW. IF THEY DO RETURN THEY WILL
LIKELY LAST UNTIL MID MORNING SUNDAY. MVFR EXPECTED MOST AREAS
SUNDAY AFTERNOON.
&&

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

$$

SHORT TERM.....ESB
LONG TERM......TE
AVIATION.......RDM






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