Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 180824
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
324 AM CDT SAT APR 18 2015

.TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

AN UPPER LEVEL TROUGH EXITING THE CENTRAL ROCKIES WILL PUSH INTO
THE PLAINS TONIGHT...AS A RIDGE BUILDS SLIGHTLY OVER THE UPPER
OHIO VALLEY REGION TOWARDS LAKE MICHIGAN. THE UPPER LEVEL
DIVERGENCE INCREASES THIS AFTERNOON AND EVENING. MEANWHILE A MID
LEVEL SHORTWAVE JUST NORTHEAST OF THE UPPER GREAT LAKES WILL MOVE
OFF INTO SOUTHEAST CANADA. 700 MB UPWARD MOTION INCREASES MAINLY
LATE TONIGHT. AN 850/800 MB WIND MAX REACHES THE UPPER MISSISSIPPI
VALLEY BY EARLY EVENING. 700 MB RH SATURATES OVER THE NOSE OF THE
WIND MAX...BUT THIS OCCURS NORTHWEST OF THE DELLS. THEREFORE ONLY
SMALL CHANCES OF LIGHT SHOWERS OVER WEST AREAS LATE TONIGHT.

A BACK DOOR COLD FRONT WILL PUSH SOUTH THROUGH SOUTHERN WISCONSIN
THIS MORNING. THIS FRONT WILL BRING COOLER TEMPERATURES AND
PERHAPS SOME BRIEF LOW CLOUDS...NEAR LAKE MICHIGAN...BUT NO
PRECIPITATION IS EXPECTED WITH THE FRONTAL PASSAGE. BEHIND THE
FRONT...WINDS WILL BE OUT OF THE EAST AT 15 MPH GUSTING UP TO 22
MPH. GUSTS SHOULD EASE IN THE AFTERNOON. THESE EAST WINDS WILL
BRING COOLER TEMPERATURES THAN WHAT WE HAVE HAD IN THE LAST FEW
DAYS...WITH MUCH COOLER TEMPERATURES NEAR LAKE MICHIGAN.

.SHORT TERM...SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM.

MODELS IN GENERAL AGREEMENT WITH TAKING WEAK SURFACE LOW NORTHEAST
FROM CENTRAL MINNESOTA AND DISSIPATING SUNDAY. A MORE ORGANIZED
LOW SLIDES NORTHWARD FROM THE MID MISSISSIPPI RIVER VALLEY TO
NORTHWEST INDIANA DURING THIS TIME...THEN SLIDES NORTH NORTHEAST
INTO NORTHERN LOWER MICHIGAN. THERE IS SOME VARIATION IN THE EXACT
TRACK OF THE LOW IN THE MODELS.

850 MB LOW TAKES A SIMILAR TRACK TO THE SURFACE LOW.
GFS/CANADIAN/ECMWF SHOWING SEVERAL WEAK 500 MB VORTICITY MAXIMA
MOVING NORTHEAST THROUGH THE AREA...WITH THE NAM AN OUTLIER WITH A
STRONGER SHORTWAVE TROUGH. THERE IS A DECENT AMOUNT OF LOW TO MID
LEVEL Q VECTOR CONVERGENCE THAT MOVES NORTH NORTHEAST THROUGH THE
AREA SUNDAY AFTERNOON AND EVENING.

AREA FORECAST SOUNDINGS SLOWLY MOISTEN WEST TO EAST SUNDAY...WITH
SATURATION MAINLY LATER SUNDAY INTO SUNDAY EVENING. THERE IS SOME
VARIABILITY ON QPF AMOUNTS AS WELL. FOR NOW...WILL CONTINUE HIGHER
END POPS FOR MAINLY SUNDAY AFTERNOON AND EVENING. REMOVED THUNDER
AS LITTLE TO NO INSTABILITY WAS SEEN ON AREA FORECAST SOUNDINGS.
ONSHORE WINDS WILL KEEP HIGHS SUNDAY IN THE 50S NEAR THE LAKE...TO
THE LOWER 60S INLAND.

STRONG COLD AIR ADVECTION THEN MOVES INTO THE REGION LATER SUNDAY
NIGHT INTO MONDAY...LINGERING INTO MONDAY NIGHT. BRISK WEST WINDS
WITHIN A TIGHT PRESSURE GRADIENT WILL BRING COLDER TEMPERATURES
INTO THE REGION...WHICH SHOULD LINGER FOR A GOOD PART OF NEXT
WEEK.

A CLOSED 500 MB LOW SHOULD SLOWLY SLIDE EAST SOUTHEAST INTO LAKE
SUPERIOR MONDAY AND MONDAY NIGHT. SEVERAL 500 MB VORTICITY MAXIMA
SHIFT THROUGH THE AREA DURING THIS TIME. STEEP LOW LEVEL LAPSE
RATES WITH A SMALL AMOUNT OF INSTABILITY DEVELOP BY MONDAY
AFTERNOON ON AREA FORECAST SOUNDINGS. THERE SHOULD BE ENOUGH
MIXING TO CONTINUE THE CHANCES FOR SHOWERS MONDAY INTO MONDAY
NIGHT. TEMPERATURES SHOULD GET COLD ENOUGH LATER MONDAY NIGHT FOR
A MIX OF RAIN AND SHOW SHOWERS IN PORTIONS OF THE AREA.

.LONG TERM...TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE IS
MEDIUM.

CLOSED 500 MB LOW SHOWN ON GFS/ECMWF TO CONTINUE TO SHIFT SLOWLY
EASTWARD ACROSS LAKE SUPERIOR TUESDAY INTO EAST CENTRAL ONTARIO
CANADA WEDNESDAY. STEEP LOW LEVEL LAPSE RATES REMAIN ON TUESDAY
WITH A SMALL AMOUNT OF INSTABILITY...AND GUSTY WINDS SHOULD ALLOW
FOR DEEP MIXING.

THUS...CONTINUED LOWER END POPS FOR SHOWERS TUESDAY...AND TUESDAY
NIGHT EAST. BELOW NORMAL TEMPERATURES WILL CONTINUE DURING THIS
TIME. THINGS DRY OUT ENOUGH FOR A DRY WEDNESDAY. GFS/ECMWF
CONTINUE TO DIFFER WITH TRENDS LATER IN THE WEEK...SO WILL FOLLOW
CONSENSUS OF MODELS FOR POPS AND TEMPERATURES.

&&

.AVIATION/12Z TAFS/...

AREAS OF MVFR HAZE WILL BE FOUND NEAR LAKE MICHIGAN EARLY THIS
MORNING. OTHERWISE...A COLD FRONTAL PASSAGE WILL LEAD TO GUSTY
NORTHEAST WINDS THIS MORNING. VISIBILITIES AND PERHAPS CIGS MAY
BRIEFLY DROP TO MVFR ALONG THE FRONT NEAR LAKE MICHIGAN THIS
MORNING. VFR CONDITIONS WILL CONTINUE AS DRY AIR IS IN PLACE AHEAD
OF AND BEHIND THE COLD FRONT.

&&

.MARINE...

A TRAILING COLD FRONT FROM LOW PRESSURE MOVING EAST ACROSS
SOUTHERN CANADA WILL ACCELERATE SOUTH OVER LAKE MICHIGAN EARLY
THIS MORNING...MOVING ACROSS THE WESTERN NEARSHORE WATERS OF LAKE
MI FROM 5 OR 6 AM NEAR SHEBOYGAN TO AROUND 8 AM AT KENOSHA.
NORTHEAST WIND GUSTS AROUND 25 TO 30 KTS ARE EXPECTED WITH THE
PASSAGE OF THE FRONT. BRISK AND GUSTY NORTHEAST WINDS WILL
CONTINUE THROUGH MUCH OF THE DAY. WAVES WILL QUICKLY BUILD TO 3 TO
5 FEET DURING THE MORNING.

&&

.FIRE WEATHER...

NEAR-CRITICAL FIRE WEATHER CONDITIONS WILL EXIST OVER SOUTH
CENTRAL WISCONSIN THIS AFTERNOON. TEMPERATURES WILL APPROACH 70
DEGREES SOUTHWEST OF MADISON. A BACK DOOR COLD FRONT WILL PUSH
SOUTH THIS MORNING. BEHIND THIS FRONT...THE RELATIVE HUMIDITY WILL
DROP TO NEAR 25 PERCENT WITH EAST WINDS UP TO 15 MPH WITH SOME
GUSTS AROUND 22 MPH.

TEMPERATURES WILL BE COOLER OVER SOUTHEAST WISCONSIN DUE TO
NORTHEAST WINDS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 4 PM CDT THIS
     AFTERNOON FOR LMZ645-646.

     SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LMZ643-
     644.

&&

$$

TODAY/TONIGHT AND AVIATION/MARINE/FIRE WEATHER...HENTZ
SUNDAY THROUGH FRIDAY...WOOD



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