Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 160233
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
933 PM CDT WED OCT 15 2014

.UPDATE...

THE LEADING EDGE OF AN AREA OF SHOWERS OVER LAKE MICHIGAN APPEARS
TO BE ERODING/POSSIBLE SUBSIDENCE REGION OF A GRAVITY WAVE?/ WHICH
ALSO SEEMS TO BE THE REASON FOR THE DISSIPATION OF AN AREA OF
SHOWERS OVER THE SE CORNER EARLIER THIS EVENING. WILL STILL SEE
SCT SHOWERS/PATCHY DRIZZLE OVERNIGHT.

BACK EDGE OF LOW CLOUDS IS JUST WEST OF MSN BUT LATEST NAM LOW-
LAYER RH FORECASTS SUPPORT CLOUDS HOLDING IN OVER ALL BUT THE FAR
WEST THROUGH THE OVERNIGHT...WITH SLOW IMPROVEMENT FROM EAST TO
WEST THURSDAY. AREAS IN THE WEST THAT DO BREAK OUT WILL SEE
FOG...SOME LOCALLY DENSE. EASTERN LOCATIONS WILL SEE PATCHY/AREAS
OF FOG BUT VSBYS SHOULD STAY NO LOWER THAN 1 MILE...WITH SOME
SPOTTY 1/4 TO 1/2 MILE VSBYS.

&&

.AVIATION/06Z TAFS/...

BACK EDGE OF LOW CLOUDS IS JUST WEST OF MSN BUT LATEST NAM LOW-
LAYER RH FORECASTS SUPPORT MVFR/IFR CLOUD DECK HOLDING IN OVER
ALL BUT THE FAR WEST THROUGH THE OVERNIGHT...WITH SLOW IMPROVEMENT
FROM EAST TO WEST THURSDAY. TAF LOCATIONS WILL SEE DRIZZLE AND AREAS
OF FOG BUT VSBYS SHOULD STAY NO LOWER THAN 2 MILES...WITH SOME
SPOTTY 1/4 TO 1/2 MILE VSBYS.

&&

.MARINE...

KEPT SMALL CRAFT ADVISORY GOING UNTIL EXPIRATION AS WINDS PICKED
UP LATE THIS AFTERNOON WITH TIGHT PRESSURE GRADIENT DROPPING SE
ACROSS THE NEARSHORE WATERS BEHIND SURFACE LOW CONSOLIDATING OVER
CENTRAL INDIANA. WILL ALLOW IT TO EXPIRE AT 03Z AS WINDS HAVE
FALLEN BELOW CRITERIA AND WILL CONTINUE TO DIMINISH...THOUGH A
FEW GUSTS TO 25 KTS ARE STILL POSSIBLE FOR AN HOUR OR TWO AFTER
03Z SOUTH OF MILWAUKEE.

&&

.PREV DISCUSSION... /ISSUED 330 PM CDT WED OCT 15 2014/

TONIGHT AND THURSDAY...CONFIDENCE - MEDIUM.

SRN WI REMAINS ON NW SIDE OF UPPER LOW CIRCULATION. WATER VAPOR
CLEARLY SHOWS THE PIVOT IN THE ATMOSPHERE WITH THE LINGERING
CYCLONIC INFLUENCE HERE. MEANWHILE VISIBLE IMAGERY SHOWS THAT WHILE
THE CLEARING LINE IS NOT TOO FAR AWAY...IT IS NOT LIKELY TO EXHIBIT
MUCH EASTWARD TRANSLATION TONIGHT..WITH A SLOW EASTWARD PROGRESSION
ON THURSDAY. A FEW SHRA AND AREAS OF DZ CONTINUE TO ROTATE IN FROM
THE NE AROUND THE LOW. WITH THE CLOUD COVER PERSISTING NOT EXPECTING
A BIG DROPOFF IN TEMPS TONIGHT NOR A WIDESPREAD DENSE FOG EVENT.
HOWEVER WITH WINDS PROGGD TO EASE AND VERY MOIST BOUNDARY LAYER
WOULD STILL EXPECT SOME FOG TO FORM. LOW LEVEL RH PROGS WHICH HAVE A
GOOD HANDLE ON THE CLEARING LINE SHOW THAT THE CLOUD COVER MAY GET A
PUSH DURING THURSDAY AFTERNOON. THE WESTERN CWA WOULD GET IN ON THIS
SOONER THAN THE EAST. ANY AREAS THAT GET SOME SUN SHOULD REACH THE
LOW 60S. THE NAM MOS WHICH OFTEN TIMES OUT DUELS THE TOO OPTIMISTIC
GFS MOS IN THESE LOW CLOUD SITUATIONS...SHOWS A SLOWER EROSION OF
THE LOW LEVEL CLOUD SHIELD.

THURSDAY NIGHT THROUGH SATURDAY...FORECAST CONFIDENCE - MEDIUM.

A QUIET NIGHT IS EXPECTED THURSDAY NIGHT AS SHORT WAVE RIDGING MOVES
RAPIDLY ACROSS WI.  INCREASING LOW LEVEL MIXING AHEAD OF APPROACHING
FRONT SHOULD PREVENT TEMPERATURES FROM FALLING TOO FAR.  CLOUDS
LIKELY TO INCREASE ON FRIDAY DUE TO MODERATE MID-LEVEL SHORT WAVE
MOVING ACROSS NORTHERN WI...WITH SOUTHWARD EXTENSION CROSSING SRN WI
IN THE AFTN.  THIS SYSTEM IS MORE PROGRESSIVE THEN EARLIER GUIDANCE
AND A LITTLE STRONGER.  DEEPER MOISTURE GRAZES ERN CWA FRIDAY NIGHT
BEHIND SECONDARY PUSH OF COLDER AIR.  WL INTRODUCE SMALL POPS FRI
AFTN TO THE NORTHEAST CWA.  HOWEVER FUTURE SHIFTS MAY NEED TO BUMP
UP POPS EVEN MORE OF THIS SPEEDIER PROGRESSION CONTINUES.  BEST
CHANCE FOR -SHRA APPEARS TO BE OVER NORTHEAST CWA FRIDAY EVENING
WHEN LOWEST CONDENSATION PRESSURE DEFICITS PASS ACROSS THE AREA.
HOWEVER EVEN THEN...THE ISENTROPIC OMEGA IS WEAK.  BUMPED UP POPS IN
THIS AREA TO CHANCE FOR NOW.

FASTER EWD MOVEMENT CARRIES SMALL PRECIP THREAT TO THE EAST BY
SATURDAY BUT LINGERING THERMAL TROF AND CYCLONIC FLOW WL LIKELY KEEP
CLOUDS AROUND THROUGH MUCH OF THE MORNING.

SATURDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE - MEDIUM.

FAIRLY GOOD AGREEMENT IN THE MEDIUM RANGE GUIDANCE FOR MUCH OF THIS
FORECAST PERIOD...HOWEVER 12Z ECMWF NOT AVAILABLE.  SOUTHERN
EXTENSION OF UPPER LOW OVER CANADA BEGINS TO PIVOT NORTHEAST IN
EASTERN CANADA EARLY IN THE WEEKEND.  THIS ALLOWS WEAKENING SHORT
WAVE RIDGING TO SWEEP ACROSS THE WESTERN GTLAKES SAT NGT AND SUN.
COLDER AIR WILL HAVE SETTLED OVER SRN WI BY THIS TIME.  HENCE A COLD
NIGHT IS ANTICIPATED SAT NIGHT WITH 925H TEMPS AROUND 3C PER
ECMWF...WHILE GFS 1-2C COLDER.  GOOD RADIATIONAL COOLING WITH A
MODERATE INVERSION SHOULD RESULT IN TEMPS FALLING INTO THE UPPER 20S
TO LOWER 30S.  MAY NEED TO ISSUE FROST ADVY FOR REMAINING SOUTHEAST
COUNTIES.

SUNDAY LOOKS LIKE A PLEASANT AUTUMN DAY AS THE SHORT WAVE RIDGING
MOVES OFF TO THE EAST. LINGERING BRISK NORTHWEST FLOW WILL CARRY
SHORT WAVE TROF ACROSS WI SUN NGT AND MON.  BOTH GFS AND 00Z ECMWF
SHOWING MORE AMPLIFIED SHORT WAVE AFFECTING THE AREA AND GEM SHOWING
A CLOSED 7H CIRCULATION PASSING ACROSS MI.  COLUMN PWAT VALUES RISE
TO EXCEED THREE QUARTERS INCH SUN NGT.  WL CONTINUE HIGHER CHANCE
LEVEL POPS AND MAY BUMP UP TO LIKELY WHEN TIMING OF SYSTEM BECOMES
CLEARER.

HIGH PRESSURE BUILDING IN BEHIND THIS SYSTEM MAY RESULT IN ONSHORE
NORTHEAST FLOW MON NGT.  DELTA-T INCREASES TO AROUND 10C BUT
LINGERING LOW LEVEL MOISTURE AND CONVERGENCE NOT IMPRESSIVE.  HENCE
WL HOLD OFF ON HANGING ON TO ANY LAKE EFFECT -SHRA MON NGT AT THIS
TIME.

LATE PERIODS LOOK DRY AND COOL AS MORE AMPLIFIED LONG WAVE RIDGE
MOVES ACROSS UPPER MIDWEST MID-WEEK AHEAD OF STRENGTHENING UPSTREAM
TROF.

CPC 6-10 AND 8-14 DAY OUTLOOKS TRANSITIONS LONG WAVE RIDGING AND
STRONGLY POSITIVE HEIGHT ANOMOLY OVER CENTRAL CONUS TO MORE ZONAL
FLOW INTO THE LAST FULL WEEK OF OCT.  LARGE NEGATIVE ANOMOLY OVER
ERN PAC COULD RESULT IN MORE SIGNIFICANT SYSTEM TO AFFECT CENTRAL
CONUS BY THE END OF THE MONTH.

AVIATION/00Z TAFS/...VISIBLE SATELLITE AND WATER VAPOR ANIMATION
TELLS ALL WITH SRN WI REMAINING ENTRENCHED IN THE CIRCULATION OF THE
LARGE UPPER LOW. WIDESPREAD IFR/LIFR CEILINGS AND OCCASIONAL SHRA/DZ
PERSIST AND WILL CONTINUE FOR MUCH OF THE NIGHT AND EARLY MORNING
HOURS. CLEARING EDGE ACRS FAR SW WI INTO NW WI. THIS WILL NOT CHANGE
INTO TONIGHT AND LOW LEVEL RH PROGS SHOW QUITE A BIT OF CLOUD COVER
LINGERING INTO THURSDAY. BEST PUSH OF CLEARING LOOKS TO BE AFTER 18Z
THURSDAY.

MARINE...LARGE LOW PRESSURE FROM LAKE MICHIGAN TO THE WESTERN OHIO
RIVER VALLEY WILL GRADUALLY WEAKEN INTO TONIGHT AS IT MOVES INTO
OHIO LATE. TIGHT GRADIENT AROUND THE LOW WILL KEEP BRISK NORTH WINDS
INTO EARLY EVENING...THAT WILL GRADUALLY WEAKEN AS A RIDGE OF HIGH
PRESSURE MOVES INTO THE UPPER MISSISSIPPI VALLEY LATE TONIGHT. GOING
SMALL CRAFT EXPIRATION TIME SEEMS REASONABLE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ643>646.

&&

$$

UPDATE...REM
TONIGHT/THURSDAY AND AVIATION/MARINE...COLLAR
THURSDAY NIGHT THROUGH WEDNESDAY...MBK


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