Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 280924
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
424 AM CDT THU APR 28 2016

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 424 AM CDT THU APR 28 2016

VERY UNUSUAL SITUATION THIS MORNING WITH NEAR ZERO
DEWPOINTS ACROSS NORTHERN WISCONSIN. DEWPOINTS THIS LOW ARE RARE
EVEN IN THE AFTERNOON ON A WELL MIXED AFTERNOON DAY. THE DRY AIR
IN THE LOW LEVELS IS ALMOST ENTIRELY EVAPORATING THE RAIN OR
MELTING SNOW THAT HAS BEEN FALLING FROM CLOUDS WITH BASES AROUND
10,000 FT.

EXPECT THIS WILL PROBABLY BE THE CASE FOR THE MOST PART TODAY AND
TONIGHT BUT A FEW SPRINKLES OR LIGHT RAIN SHOWERS COULD MAKE IT TO
THE SURFACE AT TIMES SO WILL KEEP A CHANCE OF SHOWERS IN THE FORECAST.
HIGHS TODAY WILL BE A FEW DEGREES BELOW NORMAL DUE TO CLOUDS AND
AN EASTERLY FLOW OFF LAKE MICHIGAN. CLOUDS MIGHT BEGIN TO CLEAR
LATE TONIGHT BUT PROBABLY NOT IN TIME FOR FROST TO BE LIKELY. LOWS
WILL BE ABOUT FIVE DEGREES BELOW NORMAL DESPITE THE CLOUD COVER.

SKIES SHOULD BECOME PARTLY SUNNY FRIDAY WITH TEMPERATURES CLOSE
TO NORMAL EXCEPT NEAR LAKE MICHIGAN.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 424 AM CDT THU APR 28 2016

MEAN FLOW IS FORECAST TO GO FROM BLOCKY THIS WEEKEND TO HIGHLY-
AMPLIFIED BY THE MIDDLE OF NEXT WEEK AS A PROMINENT UPPER TROUGH
HITS THE WEST COAST...DOWNSTREAM UPPER RIDGING STRENGTHENS OVER
THE ROCKIES AND ANOTHER UPPER TROUGH DEVELOPS OVER EAST-CENTRAL
NOAM. INITIALLY...NE WI WILL HAVE TO DEAL WITH THE LAST CUT-OFF
PACIFIC SYSTEM THIS WEEKEND...FOLLOWED BY DRIER/MORE SEASONAL AIR
MASS EARLY NEXT WEEK. THERE IS A CONVERGING SOLUTION WITH REGARDS
TO A SHORTWAVE TROUGH TO DIG SE TOWARD/THROUGH THE GREAT LAKES ON
TUESDAY INTO WEDNESDAY. TIMING OF THIS FEATURE IS STILL IN
DOUBT...AND THIS COULD ADVERSELY AFFECT TEMPERATURES...ESPECIALLY
DAYTIME HIGHS.

NE WI TO RESIDE BETWEEN SYSTEMS FRIDAY NIGHT AS A GENERALLY WEAK
LOOKING SHORTWAVE TROUGH SWINGS SE THROUGH ONTARIO AND A SECOND
MORE IMPRESSIVE SYSTEM ORGANIZED OVER THE CENTRAL HIGH PLAINS.
THIS SECOND SYSTEM IS PARTS OF A MUCH LARGER UPPER TROUGH THAT
WILL EXTEND FROM THE CASCADES/SIERRAS TO THE CENTRAL/SOUTHERN
PLAINS. EXPECT MAINLY PARTLY CLOUDY SKIES FOR FRIDAY NIGHT WITH
MIN TEMPERATURES IN THE LOWER TO MIDDLE 30S NORTH...UPPER 30S
SOUTH.

THIS SYSTEM IS FORECAST TO ELONGATE EASTWARD TOWARD THE SOUTHERN
SECTIONS OF THE GREAT LAKES/OHIO AND TN VALLEYS ON SATURDAY. THE
MAIN BAND OF SHOWERS/THUNDERSTORMS SHOULD FOCUS ALONG A WAVY
FRONTAL BOUNDARY STRETCHED FROM THE CENTRAL PLAINS TO THE OHIO
RIVER VALLEY. THE NORTHERN FRINGE OF THIS PRECIPITATION SHIELD
WILL ATTEMPT TO LIFT NORTH INTO WI DURING THE DAY...BUT AGAIN RUN
INTO A DRY LOW-LEVEL AIR MASS AS HIGH PRESSURE TO RESIDE TO OUR
NORTH AND FEED THIS DRY AIR INTO NE WI ON E-NE WINDS. FOR NOW...
HAVE ONLY PLACED A SLIGHT CHANCE POP OVER OUR SRN TIER OF COUNTIES
FOR SATURDAY AFTERNOON AND KEPT EVERYONE ELSE DRY. MORE SUN NORTH
AND MORE CLOUDS SOUTH SHOULD PROVIDE FOR RATHER UNIFORM MAX
TEMPERATURES ON SATURDAY WITH MOST LOCATIONS IN THE 55-60 DEGREE
RANGE (COOLER LAKESIDE).

BY SATURDAY NIGHT...THE WESTERN PORTIONS OF THIS BROAD UPPER
TROUGH IS PROGGED TO CLOSE OFF INTO AN UPPER LOW OVER THE SW
CONUS...WHILE THE REST OF THE SYSTEM CONTINUES TO MOVE EAST TOWARD
THE EAST COAST. PRECIPITATION CHANCES WILL CONTINUE TO OUR SOUTH
AS MID AND UPPER-LEVEL ENERGY LINGERS. MEANWHILE...THE HIGH
PRESSURE TO OUR NORTH IS EXPECTED TO SAG SOUTH A BIT AND HELP TO
SHOVE ANY PRECIPITATION FARTHER TO THE SOUTH. MAY NEED TO TRIM
POPS IN THE SOUTH FOR LATER SATURDAY NIGHT AND BRING MORE CLEARING
TO THE NORTH. MIN TEMPERATURES TO RANGE FROM THE MID 30S NORTH...
UPPER 30S TO AROUND 40 DEGREES SOUTH. PRECIPITATION IS EXPECTED TO
CONTINUE SKIRTING BY JUST TO OUR SOUTH ON SUNDAY...BUT BELIEVE
ENOUGH DRY AIR BEING ADVECTED INTO NE WI BY THE SURFACE HIGH
PRESSURE TO KEEP OUR WEATHER DRY. ONCE AGAIN...MORE SUN NORTH THAN
SOUTH SHOULD PROVIDE FOR UNIFORM TEMPERATURES WITH MAXES GENERALLY
IN THE UPPER 50S TO LOWER 60S (COOLER AGAIN NEAR LAKE MI).

THE AREA OF HIGH PRESSURE IS EXPECTED TO BE THE MAIN WEATHER
FEATURE AFFECTING NE WI THROUGH MONDAY...THEREBY ALLOWING FOR
PLENTY OF SUNSHINE...LIGHTER WINDS AND MORE TYPICAL TEMPERATURES
FOR EARLY MAY. LOOK FOR READINGS ON MONDAY TO REACH THE MID 50S
NEAR LAKE MI...LOWER TO MID 60S FOR MOST OTHER LOCATIONS.

THE MEAN FLOW TO BECOME HIGHLY-AMPLIFIED EARLY NEXT WEEK WITH AN
UPPER RIDGE BUILDING OVER THE ROCKIES AND A DOWNSTREAM UPPER
TROUGH TO DEVELOP OVER EAST-CENTRAL NOAM. THIS WOULD SET-UP A NW
FLOW ALOFT INTO WI AND THE MODELS ARE NOW IN BETTER AGREEMENT WITH
THE MOVEMENT OF A SHORTWAVE TROUGH INTO THE GREAT LAKES MONDAY
NIGHT INTO TUESDAY. THIS SYSTEM HAS A DYNAMIC LOOK TO IT AND WE
COULD SEE A BETTER CHANCE OF SHOWERS THAN FIRST THOUGHT. HAVE
RAISED POPS INTO THE CHANCE CATEGORY FOR NOW AS TIMING COULD
ALWAYS CHANGE THIS FAR OUT. MORE CLOUDS AND A POTENTIAL BETTER
CHANCE FOR PRECIPATION WOULD PREVENT TEMPERATURES FROM REACHING
TOO FAR INTO THE 60S. HAVE LOWERED VALUES A TOUCH INTO THE LOWER
TO MID 60S FOR NOW.

AS THIS NEW UPPER TROUGH SETS UP OVER EAST-CENTRAL NOAM...
ADDITIONAL PIECES OF SHORTWAVE ENERGY WILL COMBINE WITH A COOL
POOL ALOFT TO KEEP A MENTION FOR SHOWERS IN THE FORECAST FOR
TUESDAY NIGHT INTO WEDNESDAY. SINCE THIS IS AN EVOLVING SYSTEM...
EXPECT TO SEE SOME MODEL SWINGS IN THE COMING DAYS...THUS POPS
WERE KEPT LOW FOR BOTH TUESDAY NIGHT AND WEDNESDAY. MAX
TEMPERATURES ON WEDNESDAY SHOULD BE CLOSE TO TUESDAY`S READINGS.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1026 PM CDT WED APR 27 2016

DRY AIR WINNING OUT THUS FAR...WITH NOTHING MORE THAN SPRINKLES
ACRS THE AREA. PCPN CHCS WL INCREASE SOME THURSDAY...BUT IT/S HARD
TO SEE MUCH PCPN OCCURRING WITH THE VERY DRY AIR THAT IS NOW AT
LOW LEVELS. PLAN TO STICK WITH PCPN FREE TAFS WITH THE 06Z
ISSUANCE.
&&

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

$$

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



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