Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 031047
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
547 AM CDT MON AUG 3 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 245 AM CDT MON AUG 3 2015

A LARGE UPPER LEVEL LOW SITUATED JUST WEST OF JAMES BAY WILL
CONTINUE TO INFLUENCE OUR WEATHER EARLY THIS WEEK AS IT SLOWLY
TRACKS EAST OVER JAMES BAY BY TUESDAY. THIS LARGE LOW WILL SPIN
MID LEVEL SHORTWAVES AROUND THE PERIPHERY OF THE LOW ACROSS THE
WESTERN GREAT LAKES AS THE AREA REMAINS IN UNSTABLE CYCLONIC
NORTHWEST FLOW. THE SHORTWAVES WILL TAKE ADVANTAGE OF COOL MID
LEVEL TEMPERATURES AND STEEP LOW LEVEL LAPSE RATES OF 8 TO 10 C/KM
TO GENERATE SHOWERS ACROSS THE NORTHERN CWA DURING THE DAYTIME AND
EARLY EVENING HOURS TODAY AND TUESDAY. FURTHER SOUTH LAPSE RATES
ARE NOT AS IMPRESSIVE WITH THE SHORTWAVES TRACKING ALONG THE
MICHIGAN AND WISCONSIN BORDER...THEREFORE HAVE CONFINED THE POPS
TO THE NORTHERN CWA. DESPITE THE INSTABILITY...THERE IS A FAIRLY
SUBSTANTIAL INVERSION AROUND 650 MB WHICH SHOULD ACT TO LIMIT
VERTICAL GROWTH AND KEEP THE ACTIVITY IN THE FORM OF SHOWERS
INSTEAD OF THUNDERSTORMS. ACTIVITY SHOULD FALL OFF AS THE SUN SETS
TONIGHT...WITH ACTIVITY EXPECTED TO PICK BACK UP ON TUESDAY ONCE
DAYTIME HEATING COMMENCES.

850 MB TEMPERATURES WILL FALL TO AROUND 10 CELSIUS ACROSS THE AREA
TODAY AND TONIGHT...KEEPING TEMPERATURES WELL BELOW THE LEVELS
EXPERIENCED THE LAST FEW DAYS. HIGH TEMPERATURES ARE EXPECTED TO
RANGE FROM THE MIDDLE TO UPPER 60S ACROSS NORTH CENTRAL
WISCONSIN...WITH MIDDLE TO UPPER 70S ACROSS CENTRAL AND EAST
CENTRAL WISCONSIN. OVERNIGHT LOWS TONIGHT WILL BE QUITE
COOL...WITH LOWS IN THE MIDDLE TO UPPER 40S ACROSS NORTH CENTRAL
WISCONSIN...WITH LOW TO MID 50S ACROSS CENTRAL AND EAST CENTRAL
WISCONSIN.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 245 AM CDT MON AUG 3 2015

THE MEDIUM RANGE MODELS ARE IN SEEMINGLY GOOD AGREEMENT UNTIL FRIDAY
WHEN THE ECMWF BRINGS A POTENT SHORTWAVE INTO THE REGION.  OTHER
MODELS DO NOT SHOW THIS WAVE SO AM SKEPTICAL OF THIS ECMWF SOLUTION
BY THIS TIME.  THE GFS ALSO BECOMES A STRONGER OUTLIER WITH A
SHORTWAVE MOVING ACROSS SOUTHERN CANADA NEXT WEEKEND.  SO WILL
FOLLOW THE ECMWF UNTIL FRIDAY...THEN LET THE EXTENDED INITIALIZATION
FINISH THE REST OF THE FORECAST.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...UPPER TROUGHING WILL BE
LIFTING NORTHEAST AWAY FROM THE REGION.  WITH MID-LEVEL MOISTURE
DEPARTING WITH THE CYCLONIC FLOW...THINK WILL HAVE A DRY NIGHT ON
TUESDAY NIGHT.  HIGH PRESSURE WILL BE AT THE SURFACE ON
WEDNESDAY...WHICH SHOULD YIELD MOSTLY SUNNY CONDITIONS OUTSIDE OF A
FEW BUILDING CLOUDS WITH THE HEAT OF THE DAY.  HIGHS MAINLY IN THE
LOW TO MID 70S.  THERE WILL BE AN INFLUX OF CIRRUS ON WEDNESDAY
NIGHT WHICH SHOULD MAKE FOR WARMER LOWS...BUT HIGH PRESSURE WILL
MAINTAIN A DRY AIRMASS IN THE LOW LEVELS.  LOWS MAINLY IN THE 50S.

REST OF THE FORECAST...A SERIES OF WEAK SHORTWAVES WILL TO BEGIN TO
DRAW CLOSER TO THE REGION ON THURSDAY.  THEY WILL BRING PERIODS OF
MID AND HIGH CLOUDS OVERHEAD...BUT GUIDANCE GENERALLY SHOWS PRECIP
FALLING APART AS IT RUNS INTO A DRIER AIRMASS OVER THE WESTERN GREAT
LAKES.  THIS TREND LOOKS TO CONTINUE FRIDAY AND SATURDAY. SHORTWAVES
MAY START TO MAKE INROADS LATE NEXT WEEKEND OR EARLY NEXT WEEK.
TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL THROUGH FRIDAY BEFORE
WARMING NEXT WEEKEND.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 547 AM CDT MON AUG 3 2015

AN UPPER LEVEL DISTURBANCE MAY PRODUCE SCATTERED SHOWERS OVER
NORTHERN WISCONSIN DURING THE AFTERNOON AND EARLY
EVENING...ACCOMPANIED BY BKN STRATOCUMULUS. COVERAGE IS EXPECTED
TO BE ISOLATED...THEREFORE WILL CONTINUE TO LEAVE OUT OF THE RHI
TAF WITH THIS ISSUANCE. WEST-NORTHWEST WINDS WILL GUST TO 15 TO
20 KTS DURING THE LATE MORNING AND AFTERNOON HOURS...THEN BECOME
LIGHT OVERNIGHT.
&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......MPC
AVIATION.......KURIMSKI


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