Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 300815
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
315 AM CDT THU APR 30 2015

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 313 AM CDT THU APR 30 2015

WRAP AROUND CLOUDS WILL SLIDE OVER EASTERN
WISCONSIN TODAY. SAT IMAGERY SHOWS MAINLY MID LEVEL CLOUDS
INITIALLY BUT SOME MVFR CIGS IN THE H850 COLD CORE OF TEMPS OVER
EASTERN UPPER MICHIGAN WILL BRUSH BY THIS MORNING AS WELL. EARLY
THIS MORNING...RADAR SHOWS WEAK SOUTHWARD MOVING RETURNS OVER
EASTERN UPPER MICHIGAN AND THE LAKE MICHIGAN REGION INCLUDING DOOR
COUNTY. WILL CONTINUE TO GO DRY BUT IT IS POSSIBLE A SPRINKLE MAY
PASS OVER THE LAKE SHORE AREA THIS MORNING.

MEANWHILE THE REST OF THE STATE WILL BE MOSTLY SUNNY AS A RIDGE
OF HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST. EVENTUALLY
THIS RIDGE WILL WORK INTO EASTERN WISCONSIN THIS AFTERNOON AND
TONIGHT FOR CLEARING SKIES.

RIDGE WILL HOLD OVER THE AREA ON FRIDAY BEFORE A WEAK SURFACE
FRONT APPROACHES FROM THE WEST. MODELS IN GENERAL...DIMINISH THIS
FRONT AND PCPN AS IT TRACKS EAST FURTHER INTO THE STATE...BUT HOW
FAR EASTWARD IN QUESTION...SO WILL CONTINUE TO CONFINE SMALL POP
MENTIONS TO CENTRAL AND NORTH CENTRAL WISCONSIN FRIDAY AFTERNOON.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 313 AM CDT THU APR 30 2015

ZONAL FLOW TO EXIST ACROSS THE CONUS THRU THE UPCOMING WEEKEND
BEFORE A SRN STREAM SHORTWAVE TROF ENTERS THE SW CONUS EARLY NEXT
WEEK. THIS UPR TROF IS PROGGED TO GET BOOTED NEWD TOWARD THE CNTRL
PLAINS BY THE MIDDLE OF NEXT WEEK DUE TO A NRN STREAM CLOSED UPR
LOW DROPPING SEWD INTO THE PACIFIC NW. FOR NE WI...THIS PATTERN WL
BRING A WARM WEEKEND WITH PCPN CHCS INCREASING SUNDAY NGT/MON WITH
THE PASSAGE OF A CDFNT AND THEN AN UNSETTLED STRETCH OF WEATHER
NEXT WEEK AS THE APPROACHING SHORTWAVE TROF INTERACTS WITH A NWD
MOVING WRMFNT.

MODELS CONT TO DOWNPLAY PCPN CHCS FRI NGT AS A WEAK SHORTWAVE
CROSSES THE AREA AND A CDFNT ESSENTIALLY FALLS APART BEFORE EVEN
REACHING NE WI. WHILE AN ISOLATED SHWR OR A FEW SPRINKLES CANNOT
BE COMPLETELY RULED OUT...PREFER TO LEAVE THE FCST DRY FOR NOW.
SOME CLOUDS WL ACCOMPANY THIS VERY WEAK SYSTEM AND THIS SHOULD
HELP HOLD TEMPS UP A BIT. LOOK FOR READINGS TO ONLY DROP INTO THE
MID 30S TO AROUND 40 DEGS NORTH...LWR TO MID 40S CNTRL/LAKESHORE
AND MID TO UPR 40S E-CNTRL WI.

A PREVAILING S-SW WIND IS EXPECTED ON SAT AND THIS SHOULD PULL
MOISTURE NWD INTO WI WITH DEW POINTS CLIMBING THRU THE 40S.
PERSISTENT WAA THRU THE DAY WL RAISE 8H TEMPS TO ALMOST +10C BY
00Z SUNDAY...THUS MAX TEMPS AWAY FROM LAKE MI/BAY OF GRB COULD
REACH THE LWR TO MID 70S. IF THESE TEMP/DEW POINT NUMBERS COME TO
FRUITION...CAPE VALUES MAY REACH 500 J/KG...ESPECIALLY OVER CNTRL
WI SAT AFTERNOON. WOULD LIKE TO SEE SOME MID OR UPR-LEVEL SUPPORT...
BUT THE MODELS DO NOT INDICATE ANY...THUS INSTABILITY ALONE WOULD
HAVE TO INITIATE PCPN. DESPITE THE GFS HINTING AT SHWR DEVELOPMENT...
DO NOT BELIEVE MOISTURE WL BE DEEP ENUF TO JUSTIFY CARRYING A POP
AND WL KEEP SAT DRY.

A BROAD UPR TROF IS PROGGED TO MOVE ACROSS THE CANADIAN PRAIRIE SAT
NGT WITH A 90 KT UPR JET RIDING ALONG THE U.S.-CANADIAN BORDER
(CENTERED OVER NRN ND/SOUTH OF LK WINNIPEG). AHEAD OF THESE
FEATURES WL BE A CDFNT THAT IS EXPECTED TO MOVE INTO THE UPR MS
VALLEY. WHILE THE MAIN LIFT/FORCING TO REMAIN TO OUR WEST SAT NGT...
THE PERSISTENT SW WINDS AT THE SFC AND INCREASING LOW-LEVEL JET
SHOULD CONT TO PUMP MOISTURE INTO WI. CANNOT DISCOUNT THE SMALL CHC
FOR WAA-INDUCED SHWRS/TSTMS TO MAKE A RUN AT CNTRL/E-CNTRL WI AS
DEEPER MOISTURE ARRIVES. MIN TEMPS WL BE MILD WITH READINGS ONLY
FALLING INTO THE MID TO UPR 40S NORTH/LAKESHORE...AROUND 50 DEGS
SOUTH.

PCPN CHCS APPEAR TO BE ON THE INCREASE ON SUNDAY AS THE CDFNT
PUSHES INTO WRN WI BY 00Z MON AND RUNS INTO AN UNSTABLE AIR MASS
OVER WI. THE SW WINDS WL RAISE DEW POINTS INTO THE LWR 50S NORTH...
MID 50S SOUTH WITH PW VALUES CLIMBING INTO THE 1.00-1.25 INCH RANGE
SUNDAY AFTERNOON. MAX TEMPS ARE FCST TO REACH THE MID 70S NORTH...
75-80 DEG RANGE SOUTH (60`S LAKESIDE). THIS WOULD ALLOW CAPE VALUES
TO PUSH 1500 J/KG OVER PARTS OF THE FCST AREA...THUS A CHC OF TSTMS
FOR THE ENTIRE FCST AREA.

BEST CHC OF SEEING A WIDESPREAD PCPN EVENT STILL LOOKS TO BE SUNDAY
NGT AS THE CDFNT DRIVES SE THRU WI AND INTERACTS WITH THE
INSTABILITY IN PLACE. LIFT WL BE FURTHER ENHANCED BY A DIFFLUENT
FLOW ALOFT AND WITH PLENTY OF MOISTURE AVAILABLE...A POTENTIAL FOR
A GOOD SOAKING RAIN LOOKS PROMISING TO ALLEVIATE THE DRY CONDITIONS
OVER THE REGION. THE CDFNT WL CONT TO SAG SE ON MON...BUT BEGIN TO
SLOW DOWN NEAR THE WI/IL BORDER AS IT ENCOUNTERS A SPRAWLING UPR
RDG OVER THE SE CONUS. WEAK SHORTWAVES MOVING ALONG THE SLOWING
BOUNDARY WL CONT TO ALLOW ADDITIONAL SHWRS/TSTMS TO DEVELOP ROUGHLY
OVER THE SRN HALF OF THE STATE. THE NORTH SHOULD DRY OUT AS AN AREA
OF HI PRES TO BE SITUATED IN THE VICINITY OF LK SUPERIOR. TEMPS WL
STILL BE ABOVE NORMAL ON MON WITH MAXS GENERALLY UPR 60S TO LWR
70S (COOLER AGAIN NEAR THE LAKE).

THE FCST FOR TUE AND WED WL COME DOWN TO EXACTLY WHERE THE
STALLING BOUNDARY TO RESIDE. MODELS DIFFER ON HOW FAR SOUTH THE
FNT CAN GET BEFORE STALLING...WHICH IMPACTS PCPN CHCS FOR CNTRL/
E-CNTRL WI. ANTICIPATE THE MODELS WL WAFFLE ON THE FRONTAL
LOCATION FOR SEVERAL DAYS TO COME...THUS HAVE FOLLOWED THE MODEL
CONSENUS WHICH KEEPS A SMALL POP FOR CNTRL/E-CNTRL WI TUE. AS THE
SW CONUS UPR TROF LIFTS NE TOWARD THE CNTRL PLAINS ON WED...THIS
SHOULD LIFT THE STALLED BOUNDARY NWD AS A WRMFNT AND BRING SHWRS/
TSTMS BACK INTO NE WI. TEMPS FOR TUE AND WED WL BE TRICKY DEPENDING
ON CLOUD COVER/PCPN. EXPECT READINGS TO DROP A BIT SINCE WE WL BE
NORTH OF THE BOUNDARY WITH A PREVAILING EASTERLY WIND...YET REMAIN
AT TO SLIGHTLY ABOVE NORMAL.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1054 PM CDT WED APR 29 2015

VFR EXPECTED TONIGHT EXCEPT THERE IS SOME POSSIBILITY
THAT AN AREA OF CLOUDS WITH CEILINGS BETWEEN 2500 AND 3500 FEET
WILL MOVE FROM LAKE SUPERIOR INTO EASTERN WISCONSIN LATE TONIGHT
AND EARLY THURSDAY. OTHERWISE VFR WEATHER IS EXPECTED THURSDAY.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......AK
AVIATION.......RDM






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