Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 222055
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
355 PM CDT TUE JUL 22 2014

.TONIGHT...FORECAST CONFIDENCE - MEDIUM.

HEAT INDEX VALUES ENDED UP EXCEEDING 100 FROM MADISON AND WEST LATE
THIS AFTERNOON AFTER THE LOW CLOUDS CLEARED AWAY. MADISON REACHED A
HIGH OF 90 OR GREATER FOR THE FIRST TIME THIS YEAR.

SPC TRIMMED THE SLIGHT RISK A LITTLE FURTHER SOUTHEAST AGAIN WITH
THE 3 PM UPDATE. MESOSCALE MODELS CONTINUE TO KEEP THE AREA CAPPED
/NO CONVECTION/ UNTIL THE FRONT GETS INTO FAR SOUTHEAST WI OR EVEN
NORTHEAST IL LATE THIS AFTERNOON BETWEEN 22Z AND 00Z. SPC
MESOANALYSIS RAP IS SHOWING ERODING CIN ALONG THE FRONT IN CENTRAL
WI...SO I WILL CONTINUE THE SLIGHT CHANCE ALONG THE FRONT AS IT
MOVES SOUTHEAST THROUGH THE MKX FORECAST AREA. WE CANNOT RULE STORM
DEVELOPMENT GIVEN THE HIGH DEWPOINTS...SURFACE FRONT...VERY HIGH
CAPE OVER 4000 J/KG AND SIGNS OF SLIGHT UPSTREAM COOLING AT 700-
850MB.

THE INHIBITING FACTORS FOR CONVECTION ARE:  THE CAP. THE WESTERLY
WINDS JUST AHEAD OF THE SURFACE AND 850MB FRONTS ARE LIMITING THE
LOW LEVEL CONVERGENCE.  WE WILL HAVE TO SIT AND WAIT TO SEE IF THE
CAP BREAKS AS THE SURFACE FRONT REACHES SOUTHEAST WI. THERE IS
LIMITED BULK SHEAR OF 25 TO 30 KNOTS. ISOLATED SEVERE HAIL AND WINDS
WILL BE POSSIBLE. PRECIPITABLE WATER VALUES AROUND 2 WILL LEAD TO
VERY HEAVY RAIN WITH ANY THUNDERSTORMS. URBAN FLOODING WILL BE
POSSIBLE.

PRECIP CHANCES EXIT WITH FRONT LATE THIS EVENING WITH COOLER AND
DRIER AIR MOVING IN. TEMPERATURES DOWN INTO THE LOWER 60S AND DEW
POINTS IN THE MID TO UPPER 50S BY WEDNESDAY MORNING.

WEDNESDAY...FORECAST CONFIDENCE HIGH.

HIGH PRESSURE...DRIER AND AND COOLER TEMPERATURES WILL SETTLE INTO
THE REGION. LOOK FOR DIURNAL CUMULUS CLOUDS TO DEVELOP BY LATE
MORNING AND LINGER THROUGH EARLY AFTERNOON DUE TO STEEP LOW LEVEL
LAPSE RATES. STEADY NORTH WINDS WILL GRADUALLY DIMINISH DURING THE
AFTERNOON. WINDS WILL BE HIGHEST NEAR THE LAKE.

.WEDNESDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE - HIGH.

THE QUIET AND LESS HUMID WEATHER WILL CONTINUE THROUGH THURSDAY AS A
HIGH PRESSURE RIDGE AND DRIER DEWPOINTS HOLD SWAY ACROSS THE WESTERN
GTLAKES.  EXPECT PATCHY FOG LATER WED NIGHT DUE TO LIGHT BOUNDARY
LAYER WINDS AND LINGERING DEWPOINTS IN THE LOW TO MID 50S.  EXPECT
SOME LOCATIONS TO DIP DOWN INTO THE 40S LATE WED NIGHT.

THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE - LOW.

CONSIDERABLE DIFFERENCES BETWEEN SHORT TERM GUIDANCE IN HANDLING OF
LOW TO MID LEVEL FORCING DURING THIS PERIOD.  GFS ONLY GUIDANCE IN
BRINGING CONVECTION ASSOCIATED WITH WARM FRONT SOUTHEAST ACROSS
SOUTHERN WI ON FRIDAY.  MEANWHILE...CANADIAN MAINTAINS WMFNT
ORIENTATION FARTHER SOUTH ACROSS MO/SRN IL.  LATEST ECMWF A BLEND
BETWEEN THE TWO WHICH CLIPS PORTIONS OF SW INTO SOUTH CENTRAL WI
WITH CONVECTION GENERATED BY MOISTURE AND WARM AIR ADVECTION RETURN.
WL LEAN TOWARD MORE SOUTHERN SOLUTION AND KEEP LOWER POPS IN THE
WEST AND SOUTH DURING THIS PERIOD AS LEANING TOWARD DRIER SOLUTION
WITH BETTER CHANCE FOR CONVECTION FARTHER WEST AND SOUTH.  ECMWF AND
NAM SHOW STRONGER W-NW FLOW STEERING FLOW ACROSS SRN WI WHILE GFS
STRONGER SW. GFS REMAINS OUTLIER AT THIS POINT.  TOO MANY
DESCREPANCIES SO CONFIDENCE REMAINS LOW.

.FRIDAY NIGHT THROUGH TUESDAY - FORECAST CONFIDENCE - LOW
TRENDING TOWARD MEDIUM.

LIKE NCEP WPC BLENDED...PREFER ENSEMBLE OF MEDIUM RANGE GUIDANCE FOR
THIS FORECAST PERIOD.  MOST OF THE MEDIUM RANGE GUIDANCE IS SHOWING
SOMEWHAT BETTER AGREEMENT THAN 24 HOURS AGO...AND ARE CONVERGING ON
A SOMEWHAT SIMILAR SOLUTION.

WEAKENING MID-LEVEL RIDGE OVER NORTHERN PLAINS CONTINUES TO WEAKEN
AND FLATTEN EARLY THIS FORECAST PERIOD AS LOW PRESSURE MOVES ACROSS
SOUTHERN CANADA.  GFS CONTINUES TO PHASE THIS SYSTEM WITH EASTERN
CANADA LONG WAVE TROUGH A BIT QUICKER THAN CANADIAN/ECMWF SOLUTIONS.
GFS BRINGS SHORT WAVE ACROSS WI SAT NIGHT INTO SUN...WHILE OTHER
SOLUTIONS ARE SLOWER...LATER SUNDAY INTO SUNDAY NIGHT.  HENCE WL
NEED TO KEEP CHANCE POPS GOING OVER THE WEEKEND AS UPPER LEVEL
TROUGH MOVES THROUGH REGION.

BY MONDAY...NORTHWEST WINDS IN THE LOW TO MID LEVELS WILL HAVE
USHERED COOLER AND DRIER AIR INTO SRN WI...HOWEVER WEAK RIPPLES IN
FAST NORTHERLY FLOW MAY GENERATE -SHRA.

&&

.AVIATION/00Z TAFS/...

A COLD FRONT MOVING SOUTHEAST THROUGH SOUTHERN WI WILL BRING A
CHANCE OF SHOWERS AND THUNDERSTORMS ALONG IT LATE THIS AFTERNOON.
THE CHANCE WILL INCREASE AS THE FRONT GETS INTO FAR SOUTHEAST
WISCONSIN AROUND 6 PM...ESPECIALLY KENOSHA AND THEN SOUTHWARD INTO
NORTHEAST IL.

ANY THUNDERSTORMS WILL BRING MVFR CIGS/VSBYS IF THEY DEVELOP. EXPECT
VERY HEAVY RAIN. WINDS WILL BECOME NORTHWEST BEHIND THE FRONT...
THEN NORTH TO NORTHEAST OVERNIGHT. EXPECT A PERIOD OF BROKEN VFR
CUMULUS CLOUDS WED MIDDAY ON STEADY NORTHERLY WINDS.

&&

.MARINE...SMALL CRAFT ADVISORY IN EFFECT UNTIL 9 PM. WINDS AND WAVES
WILL RISE ON WEDNESDAY IN THE WAKE OF THE COLD FRONT. A SMALL CRAFT
ADVISORY WILL LIKELY BE NEEDED.

&&

BEACHES...MILWAUKEE...RACINE AND KENOSHA COUNTIES WILL BE IN A HIGH
RISK OF SWIMMING HAZARDS LATER TONIGHT AND WEDNESDAY. SHEBOYGAN AND
OZAUKEE COUNTY BEACHES WILL BE IN A MODERATE RISK OF SWIMMING
HAZARDS TONIGHT AND HIGH RISK WEDNESDAY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...

WI...NONE.
LM...SMALL CRAFT ADVY LMZ643>646 UNTIL 02Z/23.

&&

$$

TONIGHT/WEDNESDAY AND AVIATION/MARINE/BEACHES...MRC
WEDNESDAY NIGHT THROUGH TUESDAY...MBK



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