Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 230217
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
917 PM CDT SAT AUG 22 2015

.UPDATE...

MESO MODELS AND NEW 00Z NAM SHOW THE APPROACHING LINE OF SHOWERS
AND THUNDERSTORMS TO CONTINUING THE WEAKENING TREND. HOWEVER
SHOWERS AND SCATTERED THUNDERSTORMS ARE STILL EXPECTED WITH THE
COLD FRONT. RADAR TRENDS SHOW SOME INTENSIFICATION OVER EASTERN
IOWA ALONG THE FRONT.

&&

.AVIATION/06Z TAFS/...

A LINE OF SHOWERS AND SCATTERED THUNDERSTORMS IS EXPECTED TONIGHT
INTO SUNDAY MORNING.

SOME MVFR/IFR VSBYS/CIGS POSSIBLE WITHIN THUNDERSTORMS AND AS THE
COLD FRONT MOVES THROUGH...OTHERWISE VFR CONDITIONS WILL PREVAIL
THROUGH THE DAY SUNDAY.

GUSTY WEST WINDS ARE EXPECTED SUNDAY BEHIND THE COLD FRONT.

&&

MARINE...

SOUTH WINDS WILL INCREASE AHEAD OF AN APPROACHING COLD FRONT
TONIGHT. GUSTS TO 25 KNOTS SEEM LIKELY BY LATER TONIGHT FROM PORT
WASHINGTON TO SHEBOYGAN...SO A SMALL CRAFT ADVISORY BEGINS THERE
AT 09Z. WESTERLY WINDS BEHIND THE FRONT WILL LIKELY GUST TO AROUND
25 KNOTS ACROSS ALL THE NEARSHORE ZONES...SO WILL HAVE A SMALL
CRAFT ADVISORY ELSEWHERE BEGINNING AT 18Z. BOTH ADVISORIES WILL
RUN UNTIL 01Z SUNDAY EVENING.

THE HIGHEST WAVES WILL BE AROUND 4 FEET IN THE NORTHERN ZONES LATE
TONIGHT INTO SUNDAY MORNING DUE TO THE SOUTH WINDS. WAVES WILL
SLOWLY DIMINISH NEAR THE SHORE LATER SUNDAY MORNING INTO THE
AFTERNOON UNDER OFFSHORE WINDS.

&&

.PREV DISCUSSION... /ISSUED 255 PM CDT SAT AUG 22 2015/

TONIGHT AND SUNDAY...FORECAST CONFIDENCE...HIGH

A COLD FRONT WILL APPROACH THE FORECAST AREA TONIGHT...REACHING THE
WESTERN CWA BORDER BY AROUND DAYBREAK. THE FRONT WILL THEN PUSH EAST
THROUGH SOUTHERN WISCONSIN SUNDAY MORNING. PRECIPITABLE WATER VALUES
ARE PROGGED TO INCREASE TO 1.50-1.75 INCHES AHEAD OF THE FRONT...SO
PLENTY OF MOISTURE TO WORK WITH. INSTABILITY IS NOT THE BEST...BUT
ENOUGH PRESENT IN SOUNDINGS TO GO WITH CHANCE OF THUNDER. BULK SHEAR
FROM 0-6 KM INCREASES TO 30-35 KNOTS RIGHT AHEAD OF THE
FRONT...WHICH SHOULD HELP THE CONVECTION TO GET A LITTLE ORGANIZED.
MESOSCALE MODELS ARE IN DECENT AGREEMENT...SHOWING ISOLATED TO
SCATTERED SHOWERS/STORMS IN THE WEST LATE TONIGHT COMING TOGETHER
BETTER RIGHT OVER THE FORECAST EARLY SUNDAY MORNING. CONVECTION
LOOKS TO TAPER OFF TOWARD THE ILLINOIS BORDER...SO DIMINISHED POPS A
BIT TOWARD THE SOUTH.

STORMS WILL EXIT THE EAST AROUND NOON SUNDAY...WITH GENERALLY
DECREASING CLOUDS THROUGH AT LEAST EARLY AFTERNOON. COULD SEE CLOUDS
INCREASE A BIT IN THE NORTH AND NORTHWEST BY LATE AFTERNOON AS COLDER
AIRMASS BEHIND THE COLD FRONT BEGINS TO MOVE IN. WITH THE COLD FRONT
EAST OF THE FORECAST AREA BY NOON...HIGHS GENERALLY HOLD STEADY IN
THE UPPER 60S TO LOW 70S THROUGH THE AFTERNOON.

SUNDAY NIGHT THROUGH THURSDAY NIGHT...FORECAST CONFIDENCE HIGH

THE REGION WILL BE STUCK IN WEST TO NORTHWESTERLY FLOW THROUGH THE
EARLY PORTION OF NEXT WEEK AS A DEEP LOW PRESSURE SYSTEM DRIFTS
ACROSS ONTARIO WHILE A BROAD RIDGE OF HIGH PRESSURE SETTLES IN
ACROSS THE PLAINS/GREAT LAKES.

THE COLDEST BATCH OF 850MB AIR LOOKS LIKE IT BEGINS TO BE ADVECTED
IN STARTING SUNDAY NIGHT WITH THE CORE OF IT BEING OVER THE REGION
MONDAY INTO TUESDAY. MONDAY LOOKS TO BE THE COLDER OF THE TWO DAYS
CONSIDERING HOW GUSTY THE WINDS WILL BE WITH 22.12Z NAM/GFS
SOUNDINGS MIXING DOWN AROUND 20-25KT WINDS. TEMPERATURES WILL
SLOWLY IMPROVE THROUGH THE WEEK AS THE COLD WEST TO NORTHWESTERLY
FLOW WEAKENS AND THE AIR MASS MODIFIES.

FRIDAY THROUGH SATURDAY...FORECAST CONFIDENCE LOW

A COLD FRONT LOOKS LIKE IT WILL SWING DOWN FROM SOUTHERN CANADA
SOMETIME FRIDAY INTO SATURDAY WITH THE 22.12Z GFS AND ECMWF
SHOWING DIFFERENT PASSAGE TIMES. THE ECMWF IS FASTER AND BRINGS IT
THROUGH LATE FRIDAY NIGHT INTO SATURDAY WITH THE GFS STALLING IT
OUT TO THE NORTH OF THE REGION. A LITTLE FAR TO GO INTO ANY
SPECIFICS...BUT THE RETURN MOISTURE FLOW IS NOT THAT GREAT VIA THE
ECMWF SOLUTION...SO THERE MAY NOT BE MUCH INSTABILITY FOR THE
FRONT TO WORK WITH. THE GFS DOES MUCH MORE FOR THE MOISTURE RETURN
AND THUS HAS A MORE UNSTABLE ENVIRONMENT. TOO MUCH UNCERTAINTY
THIS FAR OUT TO TRY AND PEG A TREND.

AVIATION/00Z TAFS/...

SKIES WILL REMAIN MOSTLY CLEAR INTO THIS EVENING UNDER HIGH
PRESSURE. SHOWERS ARE THEN LIKELY TONIGHT INTO SUNDAY MORNING ALONG
WITH A CHANCE FOR THUNDERSTORMS. THE MOST LIKELY TIME PERIOD FOR
PRECIP IS BETWEEN MIDNIGHT AT NOON.

OTHER THAN SOME LOWER VSBYS/CIGS POSSIBLE WITHIN THUNDERSTORMS AND
AS THE COLD FRONT MOVES THROUGH...VFR CONDITIONS WILL PREVAIL
THROUGH THE DAY SUNDAY.

MARINE...

SOUTHERLY WINDS WILL INCREASE AHEAD OF AN APPROACHING COLD FRONT
TONIGHT. GUSTS TO 25 KNOTS SEEM LIKELY BY LATER TONIGHT FROM PORT
WASHINGTON TO SHEBOYGAN...SO WILL BE ISSUING A SMALL CRAFT ADVISORY
THERE BEGINNING AT 09Z. WESTERLY WINDS BEHIND THE FRONT WILL LIKELY
GUST TO AROUND 25 KNOTS ACROSS ALL THE NEARSHORE ZONES...SO WILL
HAVE A SMALL CRAFT ADVISORY ELSEWHERE BEGINNING AT 18Z. BOTH
ADVISORIES WILL RUN UNTIL 01Z.

THE HIGHEST WAVES WILL BE AROUND 4 FEET IN THE NORTHERN ZONES LATE
TONIGHT INTO SUNDAY MORNING DUE TO THE SOUTHERN WINDS. WAVES WILL
SLOWLY DIMINISH LATER SUNDAY MORNING INTO THE AFTERNOON UNDER
OFFSHORE WINDS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 PM TO 8 PM CDT SUNDAY FOR LMZ644>646.

     SMALL CRAFT ADVISORY FROM 4 AM TO 8 PM CDT SUNDAY FOR LMZ643.

&&

$$

UPDATE...HENTZ
TONIGHT/SUNDAY AND AVIATION/MARINE...DDV
SUNDAY NIGHT THROUGH SATURDAY...HALBACH


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