Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KGRB 181756
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1256 PM CDT SAT OCT 18 2014

UPDATED AVIATION PORTION FOR 18Z TAF 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 18Z TAF ISSUANCE
ISSUED AT 1256 PM CDT SAT OCT 18 2014

SKIES CLEARED ACROSS MUCH OF THE AREA LATE THIS
MORNING INTO THE EARLY PART OF THE AFTERNOON...THOUGH THERE WERE
STILL PATCHY MVFR CIGS. THERE WERE MORE WIDESPREAD MVFR CIGS
AROUND IN THE EAST AND IN NORTH CENTRAL WISCONSIN AS OF 1730Z.
EXPECT SKIES TO CLEAR ACROSS THE REST OF THE AREA LATER THIS
AFTERNOON AS SURFACE HIGH PRESSURE PUSHES EASTWARD INTO WISCONSIN
AND A WEAK MID LEVEL RIDGE APPROACHES THE STATE. 12Z SOUNDINGS FROM
KGRB/KINL/CWPL ALL HAD MOISTURE UNDER INVERSIONS WITH BASES BELOW
850MB...ALONG WITH SOME MOISTURE ABOVE 450MB...BUT PLENTY OF DRY
AIR ABOVE THE INVERSIONS. 12Z ECMWF 925MB RH FORECAST INDICATED
DRYING AT LOWER LEVELS THAT APPEARS TO BE OCCURRING. ANOTHER MID
LEVEL SHORT WAVE AND A SURFACE LOW APPROACHING THE STATE WILL
BRING AN INCREASE IN CLOUDS DURING THE MORNING ON SUNDAY WITH SOME
MVFR CIGS POSSIBLE TOWARDS MIDDAY. ANY PRECIPITATION SHOULD HOLD
OFF UNTIL THE AFTERNOON. CLOUD FORECAST GRAPHICS...FROM
ENVIRONMENT CANADA...FROM THE GEM-REG SUPPORT CLEARING TONIGHT
WITH INCREASING CLOUDS WITH...AND AHEAD OF...THE NEXT SYSTEM.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......MG





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.