Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 051947
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
247 PM CDT SUN JUL 5 2015

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 242 PM CDT SUN JUL 5 2015

MAIN FCST FOCUS TO BE ON THE SVR POTENTIAL MON AFTERNOON AS A
CDFNT MOVES INTO THE REGION. IN ADDITION TO THE SVR POSSIBILITY...
THIS SYSTEM MAY PRODUCE HEAVY RAINFALL WITH OVER AN INCH OF RAIN
ACCUMULATION APPEARING MORE LIKELY.

THE 19Z MSAS SFC ANALYSIS SHOWED A RETREATING AREA OF HI PRES OVER
THE ERN GREAT LAKES. AN AREA OF LOW PRES WAS SITUATED OVER THE
CNTRL HI PLAINS WITH A CDFNT EXTENDED NEWD THRU CNTRL SD...ERN ND/
WRN MN BORDER INTO WRN ONTARIO. RADAR MOSAIC PICKED UP A BAND OF
SHWRS AND TSTMS IN THE VCNTY OF THE CDFNT. FINALLY...A BROAD
SOUTHERLY WIND WAS CONTINUING TO PULL GULF MOISTURE NWD THRU THE
CNTRL CONUS TOWARD WI WITH DEW POINTS PUSHING 70 DEGS AS CLOSE AS
ERN IA.

RELATIVELY QUIET CONDITIONS EXPECTED FOR TNGT AS THE PREVAILING
SOUTH WIND CONT TO PUMP GULF MOISTURE INTO WI. CLOUDS WILL BE ON
THE INCREASE OVER CNTRL WI AFTER MIDNGT AS THE CDFNT APPROACHES
FROM THE WEST. THERE IS A SMALL CHC THAT THE LEADING EDGE OF
SHWRS/TSTMS COULD REACH N-CNTRL WI BY DAYBREAK. FOR THE ERN
SECTIONS OF THE FCST AREA...MOSTLY CLEAR TO PARTLY CLOUDY SKIES
WITH PATCHY FOG TO HOLD THRU THE NGT. A MILD NGT IN STORE WITH MIN
TEMPS RANGING FROM THE LWR 60S NEAR LAKE MI...GENERALLY MID 60S
ELSEWHERE WITH A FEW UPR 60S POSSIBLE.

THE CDFNT IS FCST TO MOVE THRU NW WI MON MORNING AND ESSENTIALLY
BISECT THE STATE ROUGHLY FROM IMT-LSE BY 00Z TUE. A PLETHORA OF
MOISTURE WL BE WAITING FOR THE FNT AS DEW POINTS CLIMB INTO THE
MID TO UPR 60S AND PW VALUES RISE TO AROUND 2.00". IN THE MID-
LEVELS OF THE ATMOSPHERE...A SHORTWAVE TROF IS EXPECTED TO SWEEP
EWD ALONG THE U.S.-CANADIAN BORDER AND REACH THE UPR MS VALLEY MON
AFTERNOON. THIS FEATURE WOULD PROVIDE STRONGER FORCING ACROSS NRN
WI...ALONG WITH HIGHER SHEAR VALUES. SPC HAS RAISED MOST OF THE
FCST AREA INTO A SLGT RISK OF SVR TSTMS MON AFTERNOON INTO MON
EVENING. WOULD LIKE TO SEE BETTER INSTABILITY VALUES THAN THE
1500-2000 J/KG CAPES AND THE 5.5 C/KM MID-LEVEL LAPSE RATES. THE
NAM IS TOO AGGRESSIVE WITH THE MOISTURE RETURN SENDING DEW POINTS
INTO THE LWR TO MID 70S...THUS OVERDOING THE INSTABILITY.
OVERALL...THIS LOOKS PRIMARILY LIKE A HEAVY RAIN EVENT WITH SMALL
HAIL/WIND GUSTS IN THAT 30-40 MPH RANGE. HAVE ADDED HEAVY RAIN TO
THE FCST AND HWO AS MOST LOCATIONS COULD EASILY SEE AN INCH OF
RAIN WITH ISOLATED HEAVIER AMOUNTS UNDER A PERSISTENT TSTM. MUCH
OF THE SVR POTENTIAL WL COME DOWN TO HOW FAST CLOUDS OVERSPREAD
THE AREA...ESPECIALLY OVER ERN WI. MAX TEMPS WL RANGE FROM THE LWR
TO MID 70S OVER N-CNTRL WI WHERE THE RAIN STARTS FIRST...TO THE
LWR TO MID 80S E-CNTRL WI (COOLER NEAR THE LAKE).

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 242 PM CDT SUN JUL 5 2015

TIMING OF THE COLD FRONT IS STILL THE MAIN CONCERN DURING THE
EARLY PART OF THE EXTENDED MONDAY NIGHT. THE NAM AND ECMWF HAVE
COME IN A BIT SLOWER THIS RUN THAN THE GFS AND CANADIAN
MODELS...LINGERING THE HEAVY RAIN ACROSS MUCH OF THE CWA DURING
THE EVENING HOURS AS THE FRONT TRACKS THROUGH THE WESTERN GREAT
LAKES. GIVEN THE GENERAL TREND OF A SLOWER FROPA WILL ADJUST POPS
TO REFLECT A LONGER RESIDENCE TIME IN THE HEAVY RAIN AND ADD HEAVY
RAIN TO THE EVENING PERIODS.

SEVERE WEATHER WILL STILL BE A CONCERN DURING THE EARLY EVENING
HOURS AS MLCAPES AHEAD OF THE FRONT ARE STILL 500 TO 1000 J/KG
WITH 0 TO 6 KM BULK SHEAR VALUES OF 25 TO 30 KNOTS. SOUNDINGS
INDICATE THE MAIN THREAT WILL BE HEAVY RAIN GIVEN PWAT VALUES OF 2
TO 2.5...WITH DAMAGING WINDS POSSIBLE WITH ANY SEVERE STORMS.
GIVEN THE CAPE PROFILES AND WET BULB ZERO HEIGHTS AROUND 14K FT
LARGE HAIL DOES NOT APPEAR TO BE AS MUCH OF A THREAT.

HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING COLD
FRONT...WHICH WILL BRING IN A MUCH DRIER AND COOLER AIRMASS TO THE
REGION TUESDAY AND WEDNESDAY. THIS WILL BRING HIGH TEMPERATURES
DOWN INTO THE 60S AND 70S...WITH OVERNIGHT LOWS DOWN INTO THE 40S
ACROSS CENTRAL AND NORTH CENTRAL WISCONSIN TUESDAY NIGHT.

THE REST OF THE FORECAST IS A BIT MURKY AS SEVERAL SHORTWAVES
TRACK THROUGH THE GREAT LAKES TOWARDS THE END OF THE WEEK AND INTO
THE WEEKEND. GIVEN THE WEAKNESS OF THESE SYSTEMS THE MODELS ARE
NOT IN MUCH AGREEMENT REGARDING THE EXACT TIMING OF THESE SYSTEMS.
THEREFORE THE TYPICAL SLIGHT CHANCE AND LOW CHANCE FOR
PRECIPITATION WILL SUFFICE WITH THIS FORECAST PACKAGE.
TEMPERATURES IN THE LATE PART OF THE FORECAST WILL MODERATE BACK
INTO THE 70S BY THE END OF THE WEEK...WITH LOW 80S BACK IN THE
FORECAST BY NEXT WEEKEND.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1228 PM CDT SUN JUL 5 2015

MAINLY VFR CONDITIONS EXPECTED THIS AFTERNOON INTO THE EVENING
WITH CU FIELD TO BE IN THE 4K-5K FT RANGE. THESE CLOUDS TO
DISSIPATE THIS EVENING BEFORE PATCHY FOG DEVELOPS ONCE AGAIN LATER
TNGT. VSBYS COULD DROP INTO THE MVFR RANGE...BUT NOT ANY LOWER AS
AN INCREASING S-SW WIND DEVELOPS. HAVE INCLUDED LLWS FOR THE
OVRNGT HOURS IN ALL TAF SITES. CONDITIONS ARE FCST TO GRADUALLY
DETERIORATE FROM WEST TO EAST ON MON AS A CDFNT PUSHES INTO WI.
PRE-FRONTAL SHWRS/FEW STORMS MAY REACH CNTRL WI TAF SITES MID-LATE
MORNING...HOWEVER MAIN ACTION TO PRIMARILY BE IN THE AFTERNOON
ONCE THE CDFNT ARRIVES. POTENTIAL FOR HEAVY RAIN COULD LIMIT VSBYS
TO IFR CONDITIONS UNDER ANY TSTMS.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......KURIMSKI
AVIATION.......AK


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