Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 172331
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
631 PM CDT THU JUL 17 2014

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 233 PM CDT THU JUL 17 2014

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE CENTERED OVER THE OHIO VALLEY. A WEAK SHORTWAVE COMBINED
WITH STEEP LOW LEVEL LAPSE RATES CONTRIBUTED TO ANOTHER AFTERNOON
OF HIGH BASED CU. LIKE YESTERDAY...NO RETURNS ON AREA RADARS.
UPSTREAM CONDITIONS OVER THE NORTHERN PLAINS ARE QUIET AS
WELL...SO FORECAST CONCERNS ARE MINIMAL OVER THIS PERIOD...AND
INCLUDE CLOUDS AND TEMPS.

TONIGHT...A LARGE HIGH PRESSURE SYSTEM WILL DRIFT TOWARDS THE
EASTERN GREAT LAKES AND CONTINUE TO DOMINATE OUR WEATHER ACROSS
THE STATE. TEMPS WILL BE A LITTLE WARMER DUE TO A SLIGHT SOUTHERLY
BREEZE AND MODIFYING LOW LEVEL TEMPS. BUT SKIES WILL REMAIN MOSTLY
CLEAR WHICH WILL ALLOW TEMPS TO FALL INTO THE UPPER 40S NORTH TO
LOW TO MID 50S ELSEWHERE.

FRIDAY...LITTLE CHANGES IN REGARDS TO THE SENSIBLE WEATHER.
SOUTHERLY WINDS WILL PUSH TEMPS AND DEWPOINTS A FEW DEGREES HIGHER
THAN TODAY.  BUT THE CAP IS PROJECTED TO STRENGTHEN BETWEEN
700-650MB SO THE THREAT OF SHOWERS FORMING FROM THE HIGH BASED CU
IS TOO LOW TO INCLUDE IN THE FORECAST. THIS CU IS AGAIN EXPECTED
TO DEVELOP LATE IN THE MORNING. HIGHS IN THE MID 70S TO LOW 80S.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 233 PM CDT THU JUL 17 2014

MDLS GENERALLY AGREE WITH THE MEAN FLOW TRANSITION FROM WRN CONUS
UPR RDG/ERN CONUS UPR TROF TO A PACIFIC NW UPR TROF/CNTRL CONUS
UPR RDG/NE CONUS UPR TROF. INITIALLY...THE CNTRL CONUS UPR RDG TO
EXTEND TOWARD THE GREAT LAKES WHICH WOULD BRING WARMER AIR/CAPPED
ENVIRONMENT TO NE WI WITH LITTLE PCPN. HOWEVER...TOWARD THE MIDDLE
OF NEXT WEEK...THE UPR RDG REFOCUSES TO THE PLAINS AND BRINGS A NW
FLOW TO WI. THIS TRANSITION WOULD EVENTUALLY BRING COOLER/MORE
UNSETTLED WEATHER BACK TO THE FCST AREA. EXACTLY HOW ALL OF THIS
PLAYS OUT REMAINS THE BIGGEST FCST CHALLENGE.

EVEN THO HI PRES TO HAVE SHIFTED TOWARD NEW ENGLAND FRI NGT...NE
WI TO REMAIN UNDER ITS WRN FRINGE TO KEEP OUR WEATHER QUIET. A
PREVAILING S-SW WIND WL CONT TO PULL WARMER/MORE MOIST AIR MASS
INTO THE GREAT LAKES...JUST NOT AS FAST AS SOME OF THE MDLS
ADVERTISE. AS A RESULT...MIN TEMPS ARE EXPECTED TO DIP INTO THE
55-60 DEG RANGE OVER MOST OF THE FCST AREA.

ATTENTION TURNS TOWARD THE UPR MS VALLEY WHERE A WEAK CDFNT IS
FCST TO TRY AND PUSH TOWARD THE WRN GREAT LAKES ON SAT. PARTS OF
N-CNTRL/CNTRL WI MAY SEE SOME INCREASE IN CLOUDS DURING THE
AFTERNOON...OTHERWISE ANY PCPN TO BE TIED TO THE FNT AND REMAIN TO
OUR NW THRU THE DAY. MAX TEMPS SHOULD BE ABLE TO REACH THE UPR 70S
TO LWR 80S INLAND...MID TO UPR 70S CLOSER TO LAKE MI.

THIS CDFNT IS PROGGED BY THE MDLS TO GRADUALLY WIPE-OUT TO OUR NW
SAT NGT...PRIMARILY DUE TO A LACK OF PUSH BEHIND IT (WINDS ALREADY
TURNING SOUTH OVER MN. FURTHERMORE...ANY UPR SUPPORT PASSES BY TO
OUR NORTH. THEREFORE...PREFER TO KEEP THE FCST DRY FOR SAT NGT
UNDER PARTLY CLOUDY SKIES. MIN TEMPS MAY BE A DEGREE OR TWO MILDER
THAN FRI NGT WHICH WOULD PLACE MOST OF NE WI AROUND THE 60 DEG
MARK. AS AN UPR TROF BEGINS TO DIG S-SE TOWARD THE PACIFIC NW ON
SUNDAY...THE DOWNSTREAM UPR RDG TO BUILD NEWD ACROSS THE MIDWEST
TOWARD WI WITH RISING UPR HEIGHTS AND WARMING 8H TEMPS. THESE
RISING UPR HEIGHTS WOULD BRING A CAP TO THE ATMOSPHERE AND PREVENT
ANY SHWRS/TSTMS FROM DEVELOPING. THE WARMING 8H TEMPS WL SEND MAX
TEMPS INTO THE LWR TO MID 80S...EXCEPT MID TO UPR 70S LAKESIDE.

SOME DOUBT CREEPS INTO THE FCST BY MON AS THE STRENGTH OF THE UPR
RDG COMES INTO QUESTION. MDLS SHOW A SHORTWAVE TROF CRUISING
ACROSS SRN CANADA AND IF THE RDG WEAKENS AT ALL...PARTS OF NRN OR
CNTRL WI WOULD BE VULNERABLE TO A PASSING SHWR OR TSTM EITHER LATE
SUNDAY NGT OR ON MON. THE REST OF NE WI SHOULD REMAIN DRY WITH A
MORE TYPICAL SUMMER DAY ON MON WITH DEW POINTS CLIMBING INTO THE
MID TO UPR 60S AND MAX TEMPS REACHING THE MID 80S (AGAIN COOLER
NEAR LAKE MI).

TIMING ISSUES COME INTO PLAY STARTING LATER MON NGT INTO TUE WITH
REGARDS TO A PRONOUNCED SHORTWAVE TROF AND CDFNT. WHILE THE LONG-
TERM MDLS AGREE NOW THAT THE UPR RDG WL REFOCUS TO THE ERN ROCKIES/
WRN PLAINS...THE MDLS CONT TO WAFFLE WITH HOW FAST TO SEND THE
SHORTWAVE TROF/CDFNT THRU WI. THE LATEST MDL OUTPUT INDICATES THAT
THE TUE/TUE NGT TIME FRAME WOULD BE THE BEST CHC OF SEEING AN AREA-
WIDE PCPN EVENT...WITH THE PCPN LINGERING INTO WED. TEMPS ARE NO
BARGAIN EITHER ON TUE AS TEMPS COULD REALLY WARM AHEAD OF THE
CDFNT. IF THIS FNT SLOW DOWN AT ALL...PARTS OF NE WI COULD BE
PUSHING THE 90 DEG MARK.

PCPN CHCS WOULD THEN TAPER OFF LATER ON WED AS THE SHORTWAVE TROF/
CDFNT DEPART. UNCERTAINTY WL CARRY OVER FROM TUE INTO WED UNTIL
ALL THE MDLS CAN CORRECTLY TIME THIS SYSTEM THRU THE REGION. BY
THU...HI PRES TO HAVE BUILT INTO THE GREAT LAKES AND BROUGHT
COOLER/LESS HUMID CONDITIONS TO NE WI WITH TEMPS SLIGHTLY BELOW
NORMAL.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 625 PM CDT THU JUL 17 2014

GOOD FLYING WEATHER WILL CONTINUE ACROSS THE REGION TONIGHT AND
FRIDAY. SCT-BKN CUMULUS/ALTOCUMULUS WILL DISSIPATE EARLY THIS
EVENING...THEN REDEVELOP AGAIN LATE FRIDAY MORNING AND AFTERNOON.
CLOUD BASES SHOULD BE MAINLY 5000-8000 FT AGL. LIGHT SOUTH WINDS
WILL INCREASE TO AROUND 10 KTS BY FRIDAY AFTERNOON.

THERE MAY BE SOME LOCALIZED FOG OVER NORTH CENTRAL WI LATE
TONIGHT...ALTHOUGH WOULD EXPECT LESS FOG THAN THE LAST TWO
NIGHTS...AS WINDS JUST OFF THE SURFACE ARE EXPECTED TO INCREASE
TO 15 TO 20 KTS. THEREFORE...WILL NOT ADD ANY FOG TO THE RHI TAF
SITE.
&&

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

$$

SHORT TERM.....MPC
LONG TERM......AK
AVIATION.......KIECKBUSCH





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