Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 101515
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1015 AM CDT WED SEP 10 2014

.AVIATION/18Z TAFS/...LOW PRESSURE IN SRN WI WILL SHIFT NORTHEAST
THIS AFTERNOON. SHRA ASSOCIATED WITH THIS FEATURE HAVE FOR THE
MOST PART PUSHED EAST OF SRN WI. PER 88-D RADAR ANIMATION DEF
ZONE PRECIP BAND MAY LEAD TO MORE SCT SHRA THIS AFTERNOON...ESP
ACRS NRN CWA. PER VSBL SATELLITE CLOUD COVER IS WIDESPREAD.
EXPECTING ANY REMAINING IFR CIGS TO TRANSITION TO MVFR ESP AS SW
THEN NW WINDS BRING IN DRIER AIR REDUCING THE SSE MOIST FLOW OVER
THE LAKE. THIS HAS RESULTED IN FOG AREAS OVER THE LAKE AND CLOSER
TO THE SHORELINE. 850 COLD AIR ADVECTION WILL CONTINUE TONIGHT
INTO THURSDAY. PER LLVL RH PROGS AND EXTENT OF CLOUD SHIELD EXPECT
SOME OF THESE MVFR CIGS TO PERSIST INTO THURSDAY...CLOSER TO IDEA
OF NAM MOS.

PC

&&

.MARINE...SMALL CRAFT ADVISORY CONTINUES. SSE FLOW WILL GRADUALLY
BECOME SW THEN NW AS THE SURFACE LOW PULLS AWAY. SO WITH THE SSE
MOIST FLOW TRANSITIONING TO OFFSHORE EXPECT THE LAKE INFLUENCE TO
EASE AND FOR THE FOG TO IMPROVE. EXPANDED FOG ADVISORY FURTHER
SOUTH AND EXTENDED UNTIL 18Z. COAST GUARD REPORTS AND WEBCAMS
SUPPORT THE EXPANSION.

PC

&&

.PREV DISCUSSION... /ISSUED 835 AM CDT WED SEP 10 2014/

UPDATE...ONLY LIGHT RAIN EXPECTED THE REST OF THE MORNING OVER
SOUTHEAST WISCONSIN AS DRIER AIR WORKING IN THE FROM THE WEST AS
STRONG FORCING ASSOCIATED WITH NEARBY SHORT WAVE MOVES OFF TO THE
EAST. HENCE CANCELLED FLASH FLOOD WATCH FROM REMAINING SOUTHEAST
COUNTIES.

PREV DISCUSSION... /ISSUED 330 AM CDT WED SEP 10 2014/

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

THE UPPER TROUGH OVER THE NORTHERN AND CENTRAL PLAINS THIS
MORNING WILL LIFT NORTHEAST AND WEAKEN...AS THE MAIN TROUGH
LINGERS ACROSS SOUTHWEST CANADA. SOUTHERN WISCONSIN IS IN THE
ENTRANCE REGION OF THE APPROACHING 110 KNOT 250 MB JET MAX THIS
MORNING...BEFORE IT PUSHES ACROSS AND REACHES NORTHERN LOWER
MICHIGAN THIS EVENING. THE STRONGEST UPPER DIVERGENCE QUICKLY
MOVES ACROSS SOUTHERN WISCONSIN THIS MORNING...AND IS NORTHEAST
AND EAST OVER THE NORTHERN GREAT LAKES AND LOWER MICHIGAN BY NOON.

A 100 KNOT 250 MB JET ALREADY EXTENDS ACROSS NEVADA AND INTO THE
CENTRAL PLAINS. ONE INITIAL JET MAX OF 85 KNOTS MOVES ACROSS
SOUTHERN WISCONSIN TODAY...WHILE THE STRONGER JET MAX IS OVER
NEBRASKA LATE TONIGHT...WITH SOUTHERN WISCONSIN IN THE EXIT
REGION. WEAK TO MODERATE UPPER DIVERGENCE MOVES ACROSS SOUTHERN
WISCONSIN WITH THE FIRST JET MAX...THEN STRONG DIVERGENCE MOVES
INTO SOUTHERN WISCONSIN DURING THE EARLY MORNING HOURS WEDNESDAY.

RATHER STRONG 700 MB WARM AIR ADVECTION THIS MORNING...AS THE LOW
STARTS TO INTENSIFY AND THE 700 MB SOUTH WINDS INCREASE TO 50
KNOTS EARLY THIS MORNING...WITH BRIEF STRONG MOISTURE
CONVERGENCE. HOWEVER...THIS IS ALREADY TO THE EAST BY MID
MORNING. THE 850 MB LAYER IS SIMILAR...WITH A 60 KNOT 850 MB JET
PUSHING INTO NORTHERN ILLINOIS AND FAR SOUTHEAST WISCONSIN DURING
THE EARLY TO MID MORNING HOURS.

THIS RESULTS IN STRONG 700 MB UPWARD MOTION DURING THE EARLY
MORNING HOURS THAT WEAKENS AS IT REACHES LOWER MICHIGAN BY NOON.

WITH THE STRONG CYCLOGENESIS THE ATMOSPHERE BECOMES
SATURATED...WITH MODELS MAINLY MOIST ADIABATIC...RESULTING IN LOW
CAPE. 500 MB TEMPERATURES ARE VERY WARM.

MAIN CONCERN WILL BE HEAVY RAINFALL. PRECIPITABLE WATER VALUES
RISE TO AROUND 2.1 INCHES OVER PORTIONS OF SOUTHEAST WISCONSIN BY
7 AM CDT...TO ALMOST 2 INCHES NORTH TOWARD SHEBOYGAN.

WITH THE QUICK HITTING DYNAMICS...MOST MODELS ARE SHOWING THE
HEAVY RAINFALL RAPIDLY DIMINISHING FROM THE WEST LATER THIS
MORNING. EXPECT THE MAIN FLOODING CONCERNS EARLY TO MID MORNING
MAINLY IN THE SOUTHEAST...ESPECIALLY IN THE MILWAUKEE TO KENOSHA
CORRIDOR. THE NCEP SLIGHT RISK OF EXCESSIVE RAINFALL DURING THIS
TIME FRAME EXTENDS FROM MILWAUKEE TO SOUTHWEST OF MADISON.

MID LEVEL DRYING OCCURS FROM THE WEST THIS MORNING...REACHING THE
FAR EAST BY NOON.

THEN THE MAIN CONCERN IS THE COOLING TEMPERATURES...WITH 850 MB
TEMPERATURES COOLING TO AROUND 5 CELSIUS TOWARD THE DELLS BY
SUNRISE.

SHORT TERM...THURSDAY THROUGH FRIDAY NIGHT...FORECAST CONFIDENCE
IS HIGH.

MODELS ARE IN GOOD AGREEMENT WITH STRONG COLD AIR ADVECTION
CONTINUING ACROSS THE AREA THURSDAY INTO THURSDAY NIGHT. THIS WILL
BRING A MUCH COOLER AND DRIER AIRMASS INTO THE AREA. HIGHS
THURSDAY WILL ONLY REACH THE UPPER 50S ACROSS THE AREA...WITH
NORTH WINDS.

HIGH PRESSURE SHIFTING SOUTH THROUGH THE CENTRAL PLAINS THURSDAY
NIGHT INTO FRIDAY WILL ALLOW WINDS TO WEAKEN AND TURN TO THE
NORTHEAST. AREAS NEAR LAKE MICHIGAN...ESPECIALLY SOUTH OF
MILWAUKEE...WILL SEE DELTA T VALUES OF AROUND 15 DEGREES CELSIUS
THURSDAY NIGHT INTO FRIDAY. THIS SHOULD HELP DEVELOP LAKE EFFECT
CLOUDS AND PERHAPS SOME SHOWERS NEAR THE LAKE.

STRONG 500 MB SHORTWAVE TROUGH THEN MOVES TOWARD THE AREA
FRIDAY...THEN ACROSS THE AREA FRIDAY NIGHT. AREA FORECAST
SOUNDINGS SHOWING DECENT AMOUNTS OF MOISTURE IN THE LOW AND MID
LEVELS DURING THIS TIME. CONTINUED HIGHER END CHANCE POPS...WITH
PERHAPS HIGHER POPS NEEDED IN LATER FORECASTS.

COOL TEMPERATURES WILL CONTINUE THURSDAY NIGHT INTO FRIDAY
NIGHT...WITH HIGHS IN THE MID 50S SATURDAY...AND LOWS IN THE 40S
EACH NIGHT. SOME UPPER 30S ARE POSSIBLE FRIDAY NIGHT WEST OF
MADISON.

LONG TERM...SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE IS
HIGH.

GFS/ECMWF THEN BRINGS HIGH PRESSURE EASTWARD TROUGH THE REGION
SATURDAY INTO SUNDAY...BRINGING QUIET WEATHER WITH CONTINUED COOL
TEMPERATURES.

MODELS THEN BRING A WEAK COLD FRONT AND DECENT 500 MB SHORTWAVE
TROUGH THROUGH THE AREA MONDAY...GFS A BIT QUICKER THAN THE ECMWF.
KEPT POPS GOING FOR MONDAY INTO MONDAY NIGHT FOR NOW...PER
CONSENSUS MODEL BLEND. ANOTHER HIGH BRINGS QUIET WEATHER FOR
TUESDAY...WITH CONTINUED COOL TEMPERATURES.

AVIATION/12Z TAFS/...

CIGS SHOULD LOWER TO MVFR THEN IFR ACROSS MUCH OF THE FORECAST
AREA...AS SHOWERS AND SCATTERED THUNDERSTORMS MOVE ACROSS
SOUTHERN WISCONSIN. WINDS AROUND 3 THSND FT WILL JUMP TO AROUND 50
KNOTS. HOWEVER...ENOUGH GRADIENT BELOW AS DEEP LOW CROSSES SW TO
NE ACROSS STATE. SURFACE WINDS SHOULD BE STRONG ENOUGH TO NOT
NEED LOW LEVEL WIND SHEAR IN TAFS.

COLD ADVECTION BEHIND THE STRONG LOW THAT WILL MOVE ACROSS
SOUTHERN/CENTRAL WISCONSIN. IFR CIGS WILL THEN RISE TO
MVFR...WITH CIGS RISING TO VFR TONIGHT...AS LOW PULLS AWAY AND
DRIER AIR MOVES IN.

MARINE...

WINDS/WAVES WILL REACH SMALL CRAFT ADVISORY CONDITIONS THROUGH
TODAY. WINDS WILL APPROACH GALE WARNING CRITERIA LATER TODAY AND
THIS EVENING...AS AN UNUSUALLY STRONG EARLY SEASON LOW INTENSIFIES
OVER WISCONSIN. THE LOW SHOULD REACH THE LAKE HURON AREA BY THIS
EVENING.

BEACHES...

BRIEF PERIOD WITH HIGH SWIM RISK WITH RIP CURRENTS. INCREASING
WAVES WITH ONSHORE SOUTHEAST FLOW THIS MORNING. THEN WHEN WINDS
BECOME MORE WEST.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...BEACH HAZARDS STATEMENT UNTIL NOON CDT TODAY FOR WIZ052-060-066-
     071-072.

LM...DENSE FOG ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR LMZ643>646.

     SMALL CRAFT ADVISORY UNTIL NOON CDT THURSDAY FOR LMZ643>646.

&&

$$

UPDATE...99
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
THURSDAY THROUGH TUESDAY...WOOD



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