Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 270904
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
404 AM CDT WED APR 27 2016

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 404 AM CDT WED APR 27 2016

UPPER LOW OVER KANSAS IS FORECAST TO MOVE SLOWLY
ACROSS NEBRASKA TODAY AND IOWA THURSDAY. MIDDLE AND HIGH CLOUDS
WILL GRADUALLY INCREASE IN WARM ADVECTION AHEAD OF THE SYSTEM. THE
CLOUDS AND A WIND OFF LAKE MICHIGAN SHOULD HOLD TEMPERATURES ABOUT
3 TO 8 DEGREES BELOW NORMAL.

JET ENERGY ROTATING AROUND AHEAD OF THE UPPER LOW IS EXPECTED TO
PRODUCE UPPER SUPPORT TO PRODUCE SOME LIGHT PRECIPITATION ACROSS
THE AREA LATER TONIGHT AND THURSDAY. THE AMOUNT AND NORTHERN
EXTENT OF THE PRECIPITATION IS UNCERTAIN AND THERE ARE DIFFERENCES
IN THE MODELS PROBABLY DUE TO THEIR FORECASTS OF THE STRENGTH AND
POSITION OF THE UPPER JETS. THE ECMWF AND GFS HAVE THE STRONGEST
JETS AND EVEN SOME WEAK COUPLING OF THEM LATE TONIGHT AND THURSDAY
MORNING WHILE THE NAM HAS WEAKER AND LESS ORGANIZED UPPER SUPPORT.
THE AIR IS INITIALLY VERY DRY BELOW 700 MB AND IT WILL TAKE AWHILE
TO MOISTEN UP. SO WE SLOWED DOWN THE ARRIVAL OF THE RAIN UNTIL
AFTER DUSK TODAY.

LIGHT RAIN OR SNOW SHOULD BE FALLING FROM A MID LEVEL DECK OF CLOUDS
LATER TONIGHT AND THURSDAY. EVAPORATIVE COOLING MAY BE SUFFICIENT
TO COOL THE BOUNDARY LAYER IN CENTRAL WISCONSIN ENOUGH TO ALLOW
SNOW TO FALL THERE FOR AWHILE LATE TONIGHT THOUGH ACCUMULATIONS
ARE DOUBTFUL. JUST RAIN IS EXPECTED ELSEWHERE. LOWS TONIGHT WILL
BE AROUND 5 DEGREES BELOW NORMAL DESPITE THE CLOUD COVER AND A
STEADY BREEZE. LIGHT RAIN POSSIBLE THURSDAY MAINLY SOUTH OF A
MERILL TO MARINETTE LINE. CLOUDS...EASTERLY FLOW AND RAIN SHOULD
KEEP TEMPERATURES 5 TO 10 DEGREES COOLER THAN TYPICAL FOR THIS
TIME OF THE YEAR.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 404 AM CDT WED APR 27 2016

THE PERSISTENT BLOCKY PATTERN OVER EASTERN CANADA/WESTERN ATLANTIC
IS FORECAST TO FINALLY BREAK DOWN THIS WEEKEND...LEAVING MODEST
UPPER RIDGING FROM SW CANADA TO THE GREAT LAKES AND A PACIFIC
SYSTEM STRETCHED FROM THE ROCKIES TO THE MID-ATLANTIC REGION. THE
MAIN FORECAST CONCERN IS HOW FAR NORTH CAN ANY PRECIPITATION GET
EARLY NEXT WEEK AS INCOMING MOISTURE TO FIGHT DRY AIR OVER WI. THE
PATTERN BREAK DOWN SHOULD ALLOW TEMPERATURES TO AT LEAST GET
CLOSER TO NORMAL WITH READINGS POTENTIALLY GOING ABOVE NORMAL BY
NEXT TUESDAY. PRECIPITATION AMOUNTS LOOK TO BE BELOW NORMAL AS THE
BULK OF THE RAIN APPEARS NOW TO STAY TO OUR SOUTH.

PRECIPITATION THREAT WILL END THURSDAY EVENING OVER CENTRAL/EAST-
CENTRAL WI AS THE WEAKENING SYSTEM CONTINUES TO TRACK EAST TOWARD
THE EASTERN GREAT LAKES. THIS LEAVES NE WI UNDER THE INFLUENCE OF
CANADIAN HIGH PRESSURE SITUATED WELL TO OUR NW (EASTERN MANITOBA/
WESTERN ONTARIO) WITH A PREVAILING LIGHT N-NE WIND. THE MAIN
QUESTION FOR THURSDAY NIGHT WILL BE HOW MUCH DRY AIR WILL WORK
INTO WI AND WHETHER ANY SUBSTANTIAL CLEARING CAN TAKE PLACE. THIS
IS CRITICAL TO MIN TEMPERATURES AS THE AIR MASS ALOFT IS STILL
QUITE COOL AND PATCHY FROST WOULD BE POSSIBLE OVER CENTRAL/EAST-
CENTRAL WI WHERE THE GROWING SEASON HAS STARTED. PREFER SKIES TO
BECOME MOSTLY CLEAR NORTH AND BECOME AT LEAST PARTLY CLOUDY
SOUTH...THUS HAVE MENTIONED THE POTENTIAL FROST IN THE HWO. MIN
TEMPERATURES TO RANGE FROM THE UPPER 20S NORTH...MID 30S SOUTH.

THE GREAT LAKES REGION TO RESIDE ON THE SOUTHERN FLANK OF THIS
EXPANSIVE CANADIAN HIGH PRESSURE ON FRIDAY...THEREBY PROVIDING FOR
MOSTLY SUNNY TO PARTLY CLOUDY SKIES...A PREVAILING E-NE WIND AND
AN UPTICK IN TEMPERATURES. READINGS ARE EXPECTED TO REACH THE
LOWER 50S NEAR LAKE MI...MID TO UPPER 50S EAST-CENTRAL WI AND NEAR
60 DEGREES OVER CENTRAL WI.

NE WI TO RESIDE BETWEEN MID-LEVEL SYSTEMS FRIDAY NIGHT WITH ONE
SYSTEM MOVING SE ACROSS SOUTHERN ONTARIO AND A SECOND...BIGGER
SYSTEM MOVING INTO THE CENTRAL/SOUTHERN PLAINS. BELIEVE SUFFICIENT
DRY AIR TO BE OVER WI TO KEEP SKY COVER GENERALLY PARTLY CLOUDY
THROUGH THE NIGHT WITH MIN TEMPERATURES RANGING FROM THE LOWER TO
MIDDLE 30S NORTH...UPPER 30S SOUTH.

THIS PLAINS SYSTEM IS PROGGED TO REMAIN NEARLY STATIONARY THROUGH
SATURDAY AS ADDITIONAL MID-LEVEL ENERGY MOVES THROUGH A BROAD
UPPER TROUGH THAT STRETCHES FROM THE WEST COAST TO THE CENTRAL
CONUS. A WAVY FRONTAL BOUNDARY IS EXPECTED TO EXTEND FROM THE
CENTRAL PLAINS SEWD TO THE TN VALLEY AND AID IN THE DEVELOPMENT OF
SHOWERS/THUNDERSTORMS AS GULF MOISTURE GETS PULLED NORTHWARD. AS
ALL OF THIS IS ONGOING...EXPECT TO SEE SOME INCREASE IN CLOUDS
OVER SOUTHERN SECTIONS OF THE FORECAST AREA...BUT NO
PRECIPITATION. NORTHERN WI COULD EASILY REMAIN MOSTLY SUNNY AS DRY
AIR CONTINUES TO FEED INTO WI FROM THE HIGH PRESSURE TO THE NORTH.
MAX TEMPERATURES TO BE SIMILAR TO FRIDAY (PERHAPS A DEGREE OR TWO
WARMER).

MODELS APPEAR TO BE CONVERGING ON A SOLUTION WHERE A LARGE PIECE
OF THIS PLAINS SYSTEM WILL GET EJECTED E-NE UP THE OHIO RIVER
VALLEY DURING THE LATTER HALF OF THE WEEKEND...WHILE THE SECOND
PIECE OF MID-LEVEL ENERGY ATTEMPTS TO CLOSE OFF INTO AN UPPER LOW
OVER THE SW CONUS. MEANWHILE...DRY AIR WILL CONTINUE TO GET PUSHED
SOUTHWARD FROM THE ONTERIO SURFACE HIGH...THUS PROSPECTS FOR
PRECIPITATION DOES APPEAR LESS THAN 24 HOURS AGO. HAVE LOWERED
POPS FOR SATURDAY NIGHT AND REMOVED THE POPS FOR SUNDAY. MAY HAVE
TO ADD A COUPLE OF DEGREES TO SUNDAY`S MAXES DUE TO LESS
PRECIPITATION WITH MOST LOCATIONS IN THE UPPER 50S TO AROUND 60
DEGREES (EXCEPT COOLER LAKESIDE).

THE START OF THE WORK WEEK NOW LOOKS MAINLY DRY AS PART OF THE
CANADIAN HIGH PRESSURE MOVES INTO THE GREAT LAKES REGION. THE ONLY
CONCERN WOULD BE A COLD FRONT THAT IS FORECAST TO DROP SOUTH ON
TUESDAY. THE GFS IS FASTER THAN THE ECMWF BY A GOOD 24 HOURS AND
SINCE THIS TIMING WILL LIKELY FLUCUATE IN THE COMING DAYS...
PREFER TO GO DRY ON TUESDAY FOR NOW AS WELL. TEMPERATURES WILL
ALSO CONTINUE TO SLOWLY WARM WITH MAX TEMPS FINALLY CLIMBING ABOVE
NORMAL BY NEXT TUESDAY.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1041 PM CDT TUE APR 26 2016

HIGH CLDS WL GRADUALLY EXPAND NE ACRS THE AREA TNGT AND
WEDNESDAY...BUT THAT SHOULD BE OF LITTLE CONCERN TO AVIATION
INTERESTS. GENERALLY GOOD FLIGHT CONDITIONS ARE EXPECTED FOR THE
NEXT 24 HRS...THOUGH SFC WINDS WILL PICK UP AND BECOME QUITE GUSTY
IN C/E-C WI AGAIN BY TOMORROW AFTN.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......SKOWRONSKI



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