Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 180912
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
412 AM CDT SAT OCT 18 2014

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 410 AM CDT SAT OCT 18 2014

CYCLONIC UPPER FLOW WITH COLD ADVECTION ACROSS LAKE SUPERIOR WAS
PRODUCING LOTS OF CLOUDS ACROSS THE REGION AT 09Z. AN UPPER JET
DROPPING SOUTH ACROSS WESTERN WISCONSIN WAS HELPING TO PRODUCE
SOME LIGHT RAIN OR SPRINKLES OVER THE CENTRAL AND EAST PART OF
THE STATE. THESE SHOULD END FROM NORTH TO SOUTH BY MID MORNING.
850MB TEMPERATURES WERE NOT QUITE COLD ENOUGH FOR SIGNIFICANT
LAKE ENHANCED PRECIPITATION BUT SOME LIGHT RAIN OR SNOW SHOWERS
POSSIBLE IN NORTH CENTRAL WISOCNSIN THROUGH MIDDAY. CLOUDS ARE
SLOW TO CLEAR AT THIS TIME OF THE YEAR BUT SATELLITE PICTURES DO
SHOW SOME CLEARING NORTH OF LAKE SUPERIOR SO DO EXPECT SOME
CLEARING LATER TODAY AS SURFACE HIGH BUILDS IN FROM MINNESOTA.

SKIES SHOULD START OUT CLEAR OR PARTLY CLOUDY THIS EVENING BUT
MIDDLE AND HIGH CLOUDS MAY ARRIVE LATE TONIGHT AS THE NEXT UPPER
TROUGH APPROACHES. WENT WITH MILDER OF THE MOS GUIDANCE DUE TO
INCREASING BOUNDARY LAYER WINDS AFTER MIDNIGHT AND THE POSSIBILITY
OF CLOUDS.

AN UPPER TROUGH AND ASSOCIATED WEAK SURFACE FRONT APPROACHES
SUNDAY AFTERNOON AND EVENING. THE ATMOSPHERE IS INITIALLY DRY SO
WE DO NOT EXPECT MUCH MORE THAN SPRINKLES OR LIGHT RAIN SHOWERS
LATE IN THE DAY.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 410 AM CDT SAT OCT 18 2014

THE WELL-ADVERTISED AMPLIFIED FLOW ACROSS THE CONUS THRU THE
MIDDLE OF NEXT WEEK STILL LOOKS ON TRACK. EVEN THO THE FLOW IS
AMPLIFIED...IT IS ALSO PROGRESSIVE WITH AN UPR RDG PLAYING A LARGE
ROLE IN NE WI WEATHER THRU MID-WEEK. THE PATTERN DOES BREAK DOWN
LATE NEXT WEEK AS THE UPR RDG REFOCUSES OVER THE SW CONUS AND THE
MAIN BAND OF WESTERLIES TO RUN FROM THE WEST COAST E-NE ALONG THE
U.S.-CANADIAN BORDER...THEN SE THRU THE ERN GREAT LAKES TO THE MID-
ATLANTIC. THE ONLY PCPN CHCS TO OCCUR SUNDAY NGT/MON AS THE
BEGINNINGS OF THE EAST COAST UPR TROF MOVES THRU THE GREAT LAKES
AND PERHAPS NEXT THU WITH THE APPROACH OF A DYING FRONTAL BOUNDARY.
TEMPS ARE EXPECTED TO START THE WEEK AT OR BELOW NORMAL AND THEN
WARM TO ABOVE NORMAL LEVELS LATE NEXT WEEK.

STRENGTHENING SHORTWAVE TROF/PASSAGE OF A CDFNT ARE STILL ON TRACK
TO MOVE ACROSS NE WI SUNDAY NGT. MAIN PROBLEMS FOR A WIDESPREAD
PCPN EVENT ARE THAT THE STRONGEST MID-LEVEL FORCING REMAINS TO OUR
NORTH AND EAST...AND LOW-LEVEL MOISTURE IS LACKING AS THE SYSTEM
ARRIVES. THEREFORE...POPS WERE KEPT AT A MINIMUM AND QPF AMOUNTS
ON THE LIGHT SIDE. MIN TEMPS TO RANGE FROM AROUND 40 DEGS NORTH...
MID 40S NEAR LAKE MI.

CYCLONIC FLOW AND CAA TO LINGER ACROSS WI THRU MON AS THE STRONG
SHORTWAVE TROF MOVES INTO THE ERN GREAT LAKES. CANNOT RULE OUT
WIDELY SCT LIGHT SHWRS TO POP UP IN THE INSTABILITY OF DAYTIME
HEATING...BUT EXPECT MOST AREAS TO BE DRY. ANOTHER CONCERN WOULD
BE POTENTIAL LAKE EFFECT FOR N-CNTRL WI AS WINDS VEER NORTH AND 8H
TEMPS TO BE AROUND 0C. OVERALL...A MOSTLY CLOUDY DAY CAN BE
EXPECTED WITH TEMPS CLOSE TO NORMAL.

THE CYCLONIC FLOW WEAKENS MON NGT AND ALLOWS A RDG OF HI PRES TO
START BUILDING TOWARD THE WRN GREAT LAKES. PARTIAL CLEARING IS
EXPECTED OVER CNTRL WI LATER AT NGT...BUT CLOUDS MAY HANG TOUGH
NORTH AND EAST AS NORTH WINDS CONT TO PULL LAKE CLOUDS INLAND. WL
HAVE TO WATCH AREAS NEAR LAKE MI AS WINDS MAY TURN N-NE ENUF TO
BRING A FEW SPRINKLES ALONG THE LAKESHORE. MIN TEMPS TO GENERALLY
RUN FROM 35-40 DEGS NORTH...UPR 30S TO LWR 40S SOUTH. IMPROVING
CONDITIONS ARE EXPECTED ACROSS ALL OF NE WI ON TUE AS THE SFC RDG
MOVES OVERHEAD AND THE UPR RDG AXIS REACHES THE MIDWEST/UPR MS
VALLEY. WINDS WL GRADUALLY SHIFT TO THE E-NE AND END ANY LAKE
EFFECT THREAT. UNDER MOSTLY TO PARTLY SUNNY SKIES...TEMPS SHOULD
BE ABOUT NORMAL FOR LATE OCTOBER (MAINLY IN THE 50-55 DEG RANGE).

THE UPR RDG SLIDES EAST AND IS FCST TO STRETCH FROM THE OZARKS
N-NE THRU THE WRN GREAT LAKES INTO ERN ONTARIO ON WED. THE DRY AIR
MASS IN PLACE WL ALLOW TEMPS TO EASILY DROP AT NGT...BUT QUICKLY
RECOVER DURING THE DAY. THE SLOW WARMING TREND WL CONT ON WED WITH
READINGS REACHING THE MID 50S OVER MOST OF THE AREA (SLIGHTLY
COOLER LAKESIDE DUE TO AN ONSHORE WIND).

THE UPR RDG BEGINS TO WEAKEN OVER WI WED NGT AS A WEAK SHORTWAVE
TROF MOVES TOWARD NRN SECTIONS OF THE GREAT LAKES AND A DIFFUSE
SFC BOUNDARY DRIFTS INTO THE UPR MS VALLEY/MIDWEST. MDLS DIFFER ON
HOW FAST THE UPR RDG BREAKS DOWN AND THE STRENGTH OF THE
APPROACHING SHORTWAVE TROF. THESE DIFFERENCES TO MAINLY IMPACT
AMOUNT OF CLOUDS WED NGT INTO THU AND AFFECTS ON TEMPS. THE GEM
APPEARS TO BREAK THE RDG DOWN TOO FAST...WHILE THE GFS MAY HANG ON
TO THE RDG TOO LONG. PREFER THE TIMING OF THE ECMWF...BUT NOT SURE
ABOUT QPF THE ECMWF GENERATES LATE WED NGT/THU MORNING. ANY FORCING
AND LIFT IN THE VICINITY OF THIS FRONTAL BOUNDARY LOOKS VERY WEAK
AT THIS TIME...SO WHILE A STRAY SHWR/SOME SPRINKLES ARE POSSIBLE...
NOT CONFIDENT ENUF YET TO MENTION IN THE FCST.

THIS BOUNDARY DOES EVENTUALLY DISSIPATE BY THU NGT AS THE UPR RDG
REFOCUSES FROM THE SW CONUS N-NE TO THE NRN PLAINS. A RETURN OF
SUNSHINE ON FRI...COUPLED WITH 8H TEMPS AROUND +12C...SHOULD YIELD
A MILD DAY ACROSS THE REGION. MAX TEMPS ON FRI COULD MAKE A RUN
INTO THE LWR TO MID 60S OR ABOUT 10 DEGS ABOVE NORMAL.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1021 PM CDT FRI OCT 17 2014

ISOLATED LIGHT SHOWERS WILL GRADUALLY END OVER MOST
LOCATIONS TONIGHT.  SOME LAKE EFFECT SNOW OR RAIN SHOWERS MAY OCCUR
LATE TONIGHT OVER FAR NORTH CENTRAL WISCONSIN. COLD AIR ON
NORTHWEST WINDS IN THE WAKE OF A COLD FRONT WILL CONTINUE TO
PRODUCE MAINLY MVFR CIGS OFF LAKE SUPERIOR TONIGHT. DRIER AIR
WORKING INTO THE AREA FROM THE NORTH MAY BEGIN TO IMPROVE CIGS TO
VFR LEVELS LATER TONIGHT OVER SOME LOCATIONS AND THEN VFR
CONDITIONS TO BECOME MORE WIDESPREAD SATURDAY.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......TDH





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