Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 301521 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1021 AM CDT TUE SEP 30 2014

.UPDATE...

LATEST MODEL SOUNDINGS INDICATE LOW LEVEL MOISTURE AND CLOUD COVER
WILL PERSIST IN THE EAST WITH SOME AFTERNOON CLEARING TO SCATTERED
OR BROKEN IN THE WESTERN AND SOUTH-CENTRAL CWA. EXPECTING CLOUDS TO
FILL IN OVERNIGHT AHEAD OF THE NEXT SYSTEM APPROACHING FROM THE
WEST. DRY CONDITIONS EXPECTED THROUGH WED MORNING.

&&

.AVIATION/18Z TAFS/...

WILL HANG ON TO STUBBORN LOW CLOUDS FOR MUCH OF TODAY...ESPECIALLY
IN THE EAST. SOME AREAS MIGHT HANG ON TO MVFR CONDITIONS INTO
WEDNESDAY. WILL EVALUATE 12Z GUIDANCE AND ADJUST TAFS ACCORDINGLY.
DRY WEATHER IS EXPECTED TONIGHT THROUGH WEDNESDAY MORNING...WITH A
CHANCE OF SHOWERS WEST IN THE AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 349 AM CDT TUE SEP 30 2014/

SHORT TERM...

TODAY...FORECAST CONFIDENCE MEDIUM

SHORT WAVE RIDGING OVER THE STATE TODAY THROUGH MOST OF TONIGHT
BETWEEN DEPARTING SHORT WAVE TROUGH OVER THE EASTERN GREAT LAKES AND
ANOTHER LIFTING ALMOST DUE NORTH THROUGH THE DAKOTAS FROM WRN
NEBRASKA.

CLOUD COVER THE BIG PROBLEM TODAY WITH COLD AIR ADVECTION TRAPPING
MOISTURE UNDER SUBSIDENCE INVERSION. NAM KEEPS CLOUDS OVER THE
REGION ROUGHLY ALONG AND EAST OF A DELLS...MADISON TO JANESVILLE
LINE THROUGH TONIGHT...WITH CLOUDS SCATTERING OUT MID-MORNING TO THE
WEST. GFS KEEPS EASTERN THIRD UNDER THE CLOUDS...WITH HRRR HOLDING
LOW CLOUDS JUST ALONG THE LAKE AFTER 17Z. WILL TREND CLOUDS WITH A
BLEND...AS COLD AIR ADVECTION EASES LATER THIS MORNING WITH A SLIGHT
UPWARD TREND IN 925 MB TEMPS THIS AFTERNOON.

MARGINAL 850 MB/LAKE SURFACE TEMPERATURE DIFFERENTIAL DEVELOPING SOME
SPRINKLES ALONG THE LAKE FROM SRN MILWAUKEE COUNTY SOUTH ON MKE TDWR
BUT THESE SHOULD DIMINISH AS 850 MB TEMPS MODERATE LATER THIS
MORNING.

CLOUDS AND COOLEST 925 MB TEMPS KEEP HIGHS IN THE MID 50S
NORTHEAST...RISING TO THE LOWER 60S SW WITH THE PROSPECT OF SOME
SUNSHINE.

TONIGHT...FORECAST CONFIDENCE MEDIUM.

MODELS KEEP 700 MB OMEGA ALONG AND WEST OF THE MS RIVER WITH BETTER
FORCING FOR ASCENT AHEAD OF APPROACHING SHORT WAVE AS FORECAST AREA
REMAINS UNDER INFLUENCE OF DEPARTING SURFACE HIGH. WILL NOT BRING
POPS INTO CWA THROUGH 12Z WEDNESDAY. LIGHT WINDS AND EXPECTED
REDUCTION IN CLOUD COVER WILL ALLOW LOWS TO FALL INTO THE LOWER 40S
EAST...WITH A BIT MORE MIXING AND WARMER 925 MB TEMPS HOLDING LOWS
IN THE MID 40S WEST.

LONG TERM...

WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM.

FLOW WILL SWITCH TO THE SOUTHWEST DURING THE MIDDLE OF THE WEEK AS A
HIGH AMPLITUDE UPPER TROUGH SLIDES ACROSS THE U.S.. AN AMPLE AMOUNT
OF MOISTURE WILL BE TAPPED FOR THIS SYSTEM. PRECIPITABLE WATER
VALUES UP TO 1.5 INCHES ARE POSSIBLE WHICH IS VERY HIGH FOR THIS
TIME OF YEAR.

THE FIRST WEAK SHORTWAVE TROUGH WILL SWING THROUGH SOUTHERN WI ON
WED...BUT LESS CONFIDENCE ABOUT ENOUGH FORCING OR MOISTURE WITH THIS
INITIAL ROUND TO ALLOW FOR PRECIP. THE NEXT STRONGER SHORTWAVE
TROUGH AND ASSOCIATED NOSE OF THE LOW LEVEL JET WILL ARRIVE THU
AFTERNOON. GIVEN THE FORCING AND STEEPER MID LEVEL LAPSE RATES...
CAPE SHOULD BE AROUND 1000 J/KG AND ALLOW FOR THUNDER. THE NAM
SUGGESTS A BREEZY DAY ON THU GIVEN THE TIGHT PRESSURE GRADIENT...
WHILE OTHER MODELS ARE MORE RESERVED. I LEANED TOWARD THE HIGHER
WINDS GIVEN THE SYNOPTIC SETUP.

TEMPERATURES WILL BE TRICKY DUE TO THE UNCERTAINTY OF HOW MUCH SUN
WILL PEEK THROUGH WHILE SOUTHERN WI IS WITHIN THE WARM SECTOR THU
AFTERNOON OR IF THE RAIN WILL KEEP THINGS COOLER. THERE IS FAIRLY
GOOD AGREEMENT THAT THE COLD FRONT WILL HOLD OFF UNTIL THU
EVENING...SO I KEPT TEMPS ON THE WARM SIDE WITH THE MODEL CONSENSUS.

SATURDAY THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM.

THE CENTER OF THE MID LEVEL UPPER LOW AND ASSOCIATED VORT MAX IS
EXPECTED TO BARREL THROUGH SOUTHERN WI FRI MORNING. THEN THE UPPER
TROUGH COULD HANG AROUND THE GREAT LAKES REGION THROUGH THE WEEKEND.
IT IS LOOKING LIKE A COOL AND CLOUDY WEEKEND WITH THE POSSIBILITY
FOR SOME LIGHT RAIN SHOWERS.

AVIATION/12Z TAFS/...

MVFR CLOUD DECK WILL HOLD THROUGH AT LEAST MID-MORNING. QUESTION
THEN IS WHEN/IF DECK SCATTERS OUT/LIFTS TO VFR. ALL GUIDANCE IS TOO
LOW WITH CURRENT STRATUS DECK BUT LEANING TOWARD MORE OPTIMISTIC
GFS/HRRR WHICH WILL SCATTER OUT AT KMSN AROUND 16Z-17Z...AND EASTERN
TAF SITES IN THE MID-AFTERNOON WHERE MOISTURE OFF THE LAKE WILL SLOW
IMPROVEMENT. GUSTY WINDS WILL DIMINISH THROUGH THE MORNING INTO THE
AFTERNOON AS GRADIENT WEAKENS WITH HIGH NOSING DOWN INTO REGION. WILL
HAVE TO WATCH FOR FOG POTENTIAL EAST AS ONSHORE FLOW BRINGS
LAKE MOISTURE INLAND.

MARINE... CURRENT END TIME FOR SMALL CRAFT ADVISORY LOOKS GOOD AS
WINDS ARE SLOWLY LOWERING AND SHOULD CONTINUE TO EASE AS HIGH
NOSES INTO REGION. WAVES SHOULD BE 4 FEET OR LESS BY 18Z.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR
     LMZ643>646.

&&

$$

UPDATE...SM/DDV
TODAY/TONIGHT AND AVIATION/MARINE...REM
WEDNESDAY THROUGH MONDAY...MRC



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