Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 251551 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1051 AM CDT SAT APR 25 2015

.UPDATE...

MESOSCALE MODELS AND UPDATED SYNOPTIC MODELS CONTINUE TO KEEP THE
MAIN AREA OF RAIN JUST SOUTH OF THE AREA TODAY. THE BEST UPWARD
VERTICAL MOTION WITH THE PASSING 500 MB SHORTWAVE TROUGH TO THE
SOUTH...AND LOW TO MID LEVEL FRONTOGENESIS RESPONSE...REMAINS IN
THIS AREA.

SEEING SOME LIGHT SHOWERS DEVELOP IN THE FAR SOUTHERN COUNTIES...SO
WILL ADJUST POPS FOR THOSE FOR THE NEXT FEW HOURS. WILL LEAVE IN
GENERALLY LOWER END POPS FOR THE SOUTHERN COUNTIES INTO MIDDLE
AFTERNOON...BEFORE TRENDING DRY TOWARD SUNSET. CLOUDS WILL LINGER
ACROSS THE SOUTH THIS AFTERNOON...WITH NORTHERN AREAS POSSIBLY
SEEING SOME BREAKS LATER THIS AFTERNOON.

EAST NORTHEAST WINDS WILL REMAIN GUSTY WITH THE TIGHT PRESSURE
GRADIENT. TEMPERATURES LOOK TO REMAIN IN THE 40S LAKESIDE...TO THE
LOWER 50S IN THE NORTHWEST...WHERE SOME BREAKS IN THE CLOUDS MAY
OCCUR LATER TODAY. MAY HAVE TO LOWER HIGHS SOME MORE IN THE SOUTH
WHERE CLOUDS WILL LINGER.

WOOD

&&

.AVIATION/18Z TAFS/...

MAY SEE LIGHT SHOWERS AT KENOSHA INTO EARLY THIS AFTERNOON...WITH
LOWER CHANCES AT THE OTHER TAF SITES...AS A TROUGH OF LOW
PRESSURE PASSES TO THE SOUTH OF THE REGION. GUSTY EAST NORTHEAST
WINDS WITH SHIFT NORTHEAST THIS AFTERNOON...WITH VFR CATEGORY
CEILINGS.

NORTHEAST WINDS WILL WEAKEN SOMEWHAT TONIGHT INTO SUNDAY...AS HIGH
PRESSURE AXIS MOVES INTO THE REGION. NORTHEAST WINDS AT 1500 FEET
ABOVE GROUND LEVEL MAY LINGER AROUND 30 KNOTS TONIGHT...BUT NOT
ENOUGH OF A WIND SPEED DIFFERENCE FROM THE SURFACE TO REQUIRE LOW
LEVEL WIND SHEAR MENTION IN TAFS.

CLOUDS WILL GRADUALLY DIMINISH FROM NORTH TO SOUTH ACROSS THE
AREA THIS EVENING...WITH MOSTLY CLEAR SKIES EXPECTED LATER TONIGHT
INTO SUNDAY.

WOOD

&&

.MARINE...

SEVERAL VESSELS PARKED IN MILWAUKEE AND RACINE HARBORS REPORTING
SUSTAINED WINDS OF 18 TO 20 KNOTS FROM THE ENE THIS MORNING.
FURTHER TIGHTENING OF THE PRESSURE GRADIENT IS EXPECTED TODAY AS
SFC LOW PRESSURE MOVES FROM MISSOURI E-SE TOWARD TN VALLEY REGION.

HOWEVER...BOTH RAP AND 12Z NAM12 SHOWING WEAK HIGH PRESSURE RIDGE
BUILDING ALONG LAKE MI WEST COAST THIS AFTN WHICH COULD PARTIALLY
BE A RESULT OF COLD LAKE MI TEMPS. RETURN OF MODIS IMAGERY
MEASURED LAKE MI SEA SURFACE TEMPS IN THE LOW 40S ON FRI.

WL CONTINUE SMALL CRAFT ADVY WITH SRN ZONES LIKELY TO HAVE MORE
FREQUENT WIND GUSTS EXCEEDING 22KTS TODAY INTO TONIGHT.
HOWEVER...PERSISTENT N TO NE FETCH WILL CAUSE WAVE HEIGHTS TO
BUILD TO 3 TO 5 FEET OVER ALL OF THE NEARSHORE. MAY BE ABLE TO
TRIM BACK END TIME OF SMALL CRAFT ADVY WITH NEW AFTN FORECAST AS
WINDS AND WAVES LIKELY TO SUBSIDE LATER TONIGHT.

MBK

&&

.PREV DISCUSSION... /ISSUED 311 AM CDT SAT APR 25 2015/

SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

THE 250 MB UPPER TROUGH WILL MOVE EAST NORTHEAST FROM KANSAS...
REACHING THE UPPER OHIO VALLEY BY EVENING. AS IT DOES THE UPPER
JET IS SUPPRESSED SOUTH...WHILE THE MAIN JET MAX MOVES OFF TOWARD
THE MID ATLANTIC STATES. LITTLE IN THE WAY OF UPPER DIVERGENCE
ACROSS SOUTHERN WISCONSIN. A STRONGER MID LEVEL TROUGH AS 500 MB
PUSHES MAINLY EAST BEFORE THE NORTHEAST U.S. AND SOUTHEAST CANADA
TROUGH ROTATES ACROSS THE NORTHERN GREAT LAKES FROM THE NORTHEAST.
MOST OF THE 700 MB UPWARD MOTION IS ALONG AND JUST SOUTH OF THE
ILLINOIS BORDER TODAY.

THE 700 MB RH IS SATURATED ALONG THE SOUTH TIER OF COUNTIES THIS
MORNING...THEN DRIES FROM THE NORTH THIS AFTERNOON AND ESPECIALLY
TONIGHT. THE 850 MB RH DRIES THIS MORNING NORTH AREAS...THEN ACROSS
THE SOUTH THIS AFTERNOON. THE 850 MB LOW WEAKENS AND ELONGATES AS IT
MOVES EAST...THEN SAGGING SOUTH THIS AFTERNOON.  THE EAST 850 MB
WINDS INCREASE THIS MORNING...THEN WEAKEN SLIGHTLY AS THEY TURN
NORTHEAST THIS AFTERNOON. THE SURFACE WINDS ALSO INCREASE THIS
MORNING...BUT REMAIN MODERATE THIS AFTERNOON.

LOW PRESSURE MOVING ACROSS THE OHIO RIVER VALLEY AND KENTUCKY REGION
TODAY MAY BRUSH THE FAR SOUTH WITH LIGHT RAIN.  THE NAM...HRRR AND
THE ARW HIGH RES MODELS KEEP PRECIPITATION MAINLY SOUTH OF
WISCONSIN...ALTHOUGH THE ARW NMN DOES HAVE SOME LIGHT PRECIPITATION
OVER THE SOUTHERN TIER AND A BIT MORE NORTH OFF LAKE MICHIGAN.

THE GFS IS THE FARTHEST NORTH OF THE MODELS...WITH THE 00Z ECMWF A
BIT FARTHER NORTH THAN THE NAM.  WILL BE CUTTING BACK ON POP
VALUES...ESPECIALLY NORTH HALF TODAY.

LONG TERM...

SUNDAY THROUGH THURSDAY... FORECAST CONFIDENCE HIGH.

DRY AIR AND MID LEVEL RIDGING WILL NOSE INTO THE WESTERN GREAT LAKES
EARLY NEXT WEEK AS A SPRAWLING CLOSED UPPER LOW OVER NEW ENGLAND
SHIFTS EAST. SURFACE HIGH PRESSURE WILL TAKE HOLD OF THE UPPER
MIDWEST AND GREAT LAKES THROUGH THURSDAY AND BRING A PLEASANT
STRETCH OF WEATHER TO SOUTHERN WI. THERE WILL BE A STEADY BREEZE OUT
OF THE NORTH THROUGH THIS PERIOD... BUT WITH THE WEAK PRESSURE
GRADIENT WE CAN EXPECT A LAKE BREEZE TO DEVELOP EACH DAY. INLAND
TEMPS WILL BE IN THE 60S FOR MOST OF THIS PERIOD WHILE LAKESHORE
TEMPS WILL BE STUCK IN THE 50S.

A MID LEVEL SHORTWAVE WILL DROP DOWN THROUGH WI TUE AFTERNOON/
EVENING. THE ECMWF ALLOWS THIS SHORTWAVE TO DEVELOP INTO A CLOSED
UPPER LOW OVER THE OHIO RIVER VALLEY...WHILE THE GFS DROPS IT INTO
THE SOUTHEAST STATES ON THE HEELS OF AN EXITING UPPER LOW. THE GFS
IS MAINTAINING A DRY FORECAST FOR TUE NIGHT/WED WHILE THE ECMWF IS
SHOWING LIGHT RAIN OVER SOUTHERN WI. THUS... KEPT SLIGHT CHANCES IN
THE FORECAST.

FRIDAY THROUGH SATURDAY... FORECAST CONFIDENCE MEDIUM.

THE ECWMF IS SHOWING A MORE ZONAL UPPER JET ALONG THE US/CANADIAN
BORDER THU NIGHT THROUGH SATURDAY. THE GFS IS SHOWING A LARGER RIDGE
OVER THE NORTHERN PLAINS/UPPER MIDWEST. THE GFS IS QUICKEST TO DRAW
VERY WARM AIR INTO SOUTHERN WI LATE NEXT WEEK. THE ECMWF IS DELAYED
WITH THE WARMING SINCE IT IS SHOWING RAIN CHANCES FRIDAY AND AGAIN
SATURDAY AFTERNOON WITH WEAK SHORTWAVES AND WARM AIR ADVECTION. IF
THE GFS PANS OUT... MAX TEMPS SHOULD BE IN THE UPPER 70S FOR NEXT
WEEKEND.

AVIATION/12Z TAFS/...

LOW PRESSURE MOVING ACROSS THE OHIO RIVER VALLEY AND KENTUCKY REGION
TODAY MAY BRUSH THE FAR SOUTH WITH LIGHT RAIN.

MAINLY VFR CIGS/VSBYS...ALTHOUGH SOME MVFR CIGS POSSIBLE FAR SOUTH
TOWARDS THE ILLINOIS BORDER...AND ALONG LAKE MICHIGAN.  CIGS WILL
RISE AND CLOUDS CLEAR FROM THE NORTH TONIGHT AS THE LOW MOVES EAST
AND HIGH PRESSURE BUILDS TOWARD LAKE SUPERIOR.

MARINE...

EAST NORTHEAST WINDS ARE EXPECTED TO INCREASE TODAY INTO THIS
EVENING.  RESULTING PERSISTENT NORTHEAST WINDS SHOULD BRING WAVES
ABOVE SMALL CRAFT ADVISORY CONDITIONS. A SMALL CRAFT ADVISORY IS IN
EFFECT FOR TODAY AND TONIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM CDT SUNDAY FOR LMZ643>646.

&&

$$

UPDATE...WOOD/MBK
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ SUNDAY
THROUGH FRIDAY...MRC



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