Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 100245 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
945 PM CDT TUE SEP 9 2014

.UPDATE...

WILL BE HOLDING ON TO FLASH FLOOD WATCH AS RAP FORECAST SOUNDINGS
AROUND 4 AM SHOW EXTREMELY STRONG OMEGA THAT CROSSES THE CWA
BETWEEN 08Z AND 15Z...PW/S IN THE 2 TO 2.2 INCH RANGE AND WARM
CLOUD DEPTH OF 13K FT WITH A LOW-LEVEL JET AROUND 50 KTS NOSING
INTO THE SW CORNER OF WI AROUND 06Z AHEAD OF RAPIDLY DEEPENING
SYSTEM THAT ACCELERATES INTO WESTERN WI BY 12Z WED.

SOME CONCERN ABOUT QPF AMOUNTS GIVEN INITIAL...MAINLY STRATIFORM
PCPN MOVING INTO CWA NOW...BUT CANT IGNORE THE ROBUST LIFT AND
MOISTURE MOVING IN AHEAD OF STRENGTHENING SYSTEM. WPC HAS QPF
BULLSEYE SOUTH INTO NRN IL...WITH A LESSER SECONDARY DEFORMATION
ZONE MAXIMA OVER THE ERN U.P./NRN LK MICHIGAN...WHILE LATEST NAM
CLIPS FAR SRN WI WITH A 2 INCH MAX...AND A HIGHER DEFORMATION ZONE
MAX THAT JUST MISSES TO THE NW.

WILL ADJUST QPF A BIT BUT BASICALLY LEAVE AMOUNTS INTACT WITH THE
POTENTIAL FOR HEAVY RAIN AFTER 06Z...AND PROBABLY CLOSER TO
09Z...THROUGH 12Z-15Z OVER THE CWA.

&&

.AVIATION/06Z TAFS/...

WHILE THERE MAY BE A FEW SPOTTY MVFR CIGS/VSBYS WITH STRATIFORM
PCPN CROSSING CWA NOW...EXPECT VFR CONDITIONS TO NOT PERMANENTLY LOWER
TO MVFR UNTIL SHOWERS AND STORMS MOVE IN AFTER 06Z AT KMSN AND
AFTER 09Z AT EASTERN TAF SITES. WINDS AROUND 3K FT WILL JUMP TO
AROUND 50 KTS BUT ENOUGH GRADIENT BELOW AS DEEP LOW CROSS SW TO NE
ACROSS STATE FOR SURFACE WINDS TO BE STRONG ENOUGH TO NOT NEED
LLWS IN TAFS.

STRONG COLD ADVECTION BEHIND LOW WILL BRING IFR CIGS IN SPITE OF
GUSTY WEST TO NORTHWEST WINDS THAT WILL SLOWLY LOWER AFTER 00Z AS
LOW PULLS AWAY.

.MARINE...SMALL CRAFT ADVISORY TIMES LOOK GOOD AND WILL BE KEPT.
MARINE DENSE FOG FOR NRN ZONES MAY BE DROPPED EARLY IF INCREASING
WINDS BREAK UP THE FOG...BUT EVEN WITH THE STRONGER WINDS...THE
HIGHER DEW POINT AIR MOVING OVER THE COOLER WATERS OFF OF
SHEBOYGAN AND PT WASHINGTON MAY KEEP ADVECTION FOG DENSE ENOUGH
FOR HEADLINE TO CONTINUE TO EXPIRATION.

&&

.PREV DISCUSSION... /ISSUED 220 PM CDT TUE SEP 9 2014/

TONIGHT AND WEDNESDAY - CONFIDENCE...MEDIUM
LOW PRESSURE WILL CONTINUE TO INTENSIFY AS IT APPROACHES WI TONIGHT.
IMPRESSIVELY STRONG 850 LLJ AVERAGING 55 TO 65 KNOTS WILL TAKE AIM
ON SRN WI LATER TONIGHT. SOUTHWEST UPPER JET WILL ENHANCE UPPER
DIVERGENCE. PRECIPITABLE WATER VALUES EXCEED 2 INCHES WITH BUFKIT
SOUNDINGS SHOWING A MOIST COLUMN THROUGH AN APPRECIABLE DEPTH. STORM
MOTIONS WILL BE ON THE HIGH SIDE BUT EXPECTING VERY EFFICIENT RAINFALL
RATES ON THE ORDER OF 1-2 IN/HOUR AT TIMES. THERE ARE STILL SOME MODEL
DIFFERENCES ON PLACEMENT OF FEATURES. THE MOST DIRECT BULLSEYE FOR
SRN WI IS THE GFS WITH THE ECMWF KEYING ON THE NRN CWA. MEANWHILE
THE GEM IS SKEWED FURTHER SOUTH INTO NRN IL WITH THE HEAVIER AXIS
INTO SE WI. MEANWHILE THE NAM HAS HEAVIEST PRECIP WITH DEF ZONE
PRECIP IN NW WI WITH A CONVECTIVE BAND INTO SRN WI. SO THIS ALL
POINTS TO THE WATCH WE HAVE. IT IS JUST A WATCH AND THERE IS STILL
SOME MODEL UNCERTAINTY ON EXACTLY HOW THIS WILL PLAY OUT. BUT GIVEN
THE POTENTIAL LAID OUT BY THE MODELS FROM A PURELY QPF STANDPOINT
THE WATCH IS CERTAINLY MERITED. THIS WILL IMPACT THE MORNING RUSH
HOUR AS WELL. STILL CONCERN FOR SOME HEFTY WINDS WITH ANY STORM CELL
AS THE STRONGER WINDS ALOFT GET TAPPED INTO AND BROUGHT DOWN TO THE
SURFACE VIA DOWNWARD MOMENTUM TRANSFER/WET MICROBURST IDEA. EXPECTING
THINGS TO WIND DOWN QUITE RAPIDLY LATE MORNING INTO EARLY AFTERNOON.
LLJ WILL SHIFT EAST AND NW WINDS AND LLVL CAA WILL BEGIN IN THE WAKE
OF THE FRONT. 2 METER TEMP PROGS SHOW RAPID DROPOFF IN SFC TEMPS DURG
THE AFTN THOUGH MOS LESS PRONOUNCED ON THE COOL DOWN. EXPECT SOME
POST-FRONTAL DROPOFF THOUGH.

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

STRONG COLD/DRY AIR ADVECTION ARRIVES BY WEDNESDAY EVENING AND
CONTINUES THROUGH THURSDAY. BRISK NORTHWEST WINDS WILL GRADUALLY
DIMINISH AS THE GRADIENT RELAXES FOLLOWING THE RAPID DEPARTURE OF
THE LOW. SKIES WILL GENERALLY REMAIN ON THE CLOUDIER SIDE WITH A
NOISY FAST MID LEVEL FLOW KEEPING AT LEAST SOME MID AND HIGH LEVEL
CLOUDS STREAMING IN HERE. THE CU RULE DOES SUPPORT DIURNAL CU ON
THURSDAY. AN APPROACHING STRONG MID LEVEL SHORT WAVE WILL REALLY
THICKEN UP THE CLOUDS BY LATE THURSDAY NIGHT.

FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.

A STRONG SHORT WAVE WILL TRACK ACROSS WISCONSIN FRIDAY INTO
FRIDAY EVENING. THE ECMWF ACTUALLY CLOSES OFF A FEW H5 HEIGHT
CONTOURS AS IT PUSHES ACROSS THE GREAT LAKES. THE GFS AND THE
CANADIAN HAVE MORE OF AN OPEN TROF. AT THE SFC THE PATTERN
REMAINS BENIGN WITH MOSTLY HIGH PRESSURE IN PLACE. THE ECMWF TRIES
TO BRING AN INVERTED TROF UP ACROSS LAKE MICHIGAN/LOWER
MICHIGAN...BUT IT IS THE STRONGEST OF THE MODELS WITH THIS SYSTEM.
DESPITE THE QUIET LOWER LEVELS...THERE IS IMPRESSIVE MID LEVEL
FRONTOGENESIS AND ENOUGH MOISTURE TO SUPPORT SOME SHOWERS FRIDAY
INTO FRIDAY EVENING.

SATURDAY AND SUNDAY...FORECAST CONFIDENCE IS HIGH.

HIGH PRESSURE AND VERY CHILLY AIR WILL BE IN PLACE THIS WEEKEND.
AT LEAST WE SHOULD SEE SOME SUNSHINE. LOOK FOR A SLIGHT MODERATION
IN TEMPS BETWEEN SATURDAY AND SUNDAY. LOWS BOTH SATURDAY AND
SUNDAY WILL BE DOWN IN THE 40S WITH SOME UPPER 30S POSSIBLE IN A
FEW SPOTS.

MONDAY...FORECAST CONFIDENCE IS MEDIUM.

THE FAST ZONAL MID LEVEL FLOW WILL BRING ANOTHER SHORTWAVE IN
HERE FOR MONDAY...POSSIBLY KICKING OFF A FEW SHOWERS. PRETTY MINOR
STUFF AT THIS POINT.

AVIATION/00Z TAFS/...LOW PRESSURE WILL CONTINUE TO STRENGTHEN AS IT
RIDES NORTHEAST INTO LATER TONIGHT INTO WEDNESDAY MORNING. VERY
HEAVY RAINFALL RATES WILL ALLOW FOR IFR CIGS/VSBYS AS RA/TSRA MOVE
ACROSS...WITH THE MAIN WINDOW BETWEEN 06Z-16Z...WEST TO EAST ACROSS
SRN WI. GUSTY SOUTH THEN SOUTHWEST WINDS WILL DEVELOP LATER THIS
EVENING AHEAD OF THE LOW AND THEN SHIFT NORTHWEST AND BECOME GUSTY
AFTER THE LOW MOVES EAST BY WEDNESDAY AFTERNOON. SOME POTENTIAL FOR
LLWS IN THE 10-14Z TIME FRAME DUE TO PROXIMITY OF STRONGER WINDS
ASSOCIATED WITH THE SOUTHERLY LOW LEVEL WIND MAX.

MARINE...WINDS/WAVES WILL REACH SMALL CRAFT ADVISORY
CONDITIONS LATE TONIGHT AND APPROACH GALE WARNING CRITERIA ON
WEDNESDAY AND WEDNESDAY EVENING AS AN UNUSUALLY STRONG EARLY SEASON
LOW INTENSIFIES OVER WISCONSIN WEDNESDAY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...FLASH FLOOD WATCH FROM 1 AM CDT WEDNESDAY THROUGH WEDNESDAY
     AFTERNOON FOR WIZ046-047-051-052-056>060-062>072.

LM...SMALL CRAFT ADVISORY FROM 4 AM WEDNESDAY TO NOON CDT THURSDAY
     FOR LMZ643>646.

     DENSE FOG ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR LMZ643-644.

&&

$$

UPDATE...REM
TONIGHT/WEDNESDAY AND AVIATION/MARINE...COLLAR
WEDNESDAY NIGHT THROUGH TUESDAY...DAVIS



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