Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 041632
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1132 AM CDT FRI SEP 4 2015

.UPDATE...


&&

.AVIATION/18Z TAFS/...

A WEAK LOW FROM THE SURFACE TO THE MID AND UPPER LEVELS OF THE
ATMOSPHERE OVER LOWER MICHIGAN IS EXPECTED TO GRADUALLY WEAKEN AS
IT MOVES SOUTHEAST. THE STRATUS WAS MAINLY MVFR FROM NEAR KENOSHA
TO EAST OF THE DELLS. THE STRATUS WAS MOVING SLOWLY
SOUTHEAST...BUT THIS PUSH HAS STOPPED AS THE LEADING EDGE MIXES
OUT WITH DAYTIME HEATING. EXPECT HIS TREND TO CONTINUE...BUT AREAS
MORE TOWARD SHEBOYGAN MAY STAY IN A STRATUS.

THUNDERSTORM CHANCES TODAY ARE VERY LOW AND MAINLY JUST AN
AFTERNOON SLIGHT CHC FOR AREAS SOUTH AND WEST OF THE STRATUS WHERE
SURFACE CAPE VALUES RISE TO AROUND 2500 JOULES/KG

EXPECT THE STRATUS AND FOG TO EXPAND AGAIN TONIGHT WITH
IFR/LIFR...ESPECIALLY IN THE CURRENTLY STRATUS AREA WITH MORE
PATCHY FOG TO THE SOUTHWEST.

MARINE...

FOG WILL CONTINUE TO BE A THREAT OVER THE NEARSHORE WATERS
THROUGH THE WEEKEND.

&&

.PREV DISCUSSION... /ISSUED 322 AM CDT FRI SEP 4 2015/

TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.

THIS WEAK FLOW PATTERN CONTINUES TO PRESENT FORECAST CHALLENGES.
A MOISTURE AXIS IN THE 925-850MB LAYER COUPLED WITH SOME WEAK
CONVERGENCE ASSOCIATED WITH A CORRESPONDING TROF AXIS HAS RESULTED
IN A PERSISTENT BAND OF CLOUDS STRETCHING NW TO SE ACROSS SOUTHERN
WISCONSIN...AND IT/S EXPANDING.

LOWER CLOUDS OVER NORTHERN INTO CENTRAL LAKE MICHIGAN HAVE A
CIRCULATION THAT TIES IT WITH THE DEEP CIRCULATION ASSOCIATED WITH
THE MID LEVEL SHORT WAVE IN THAT REGION. THOSE CLOUDS ARE SPILLING
SOUTH INTO THE SHEBOYGAN AREA AND SHOULD DRIFT FARTHER SOUTH INTO
THE MORNING. GIVEN THE WEAK FLOW...IT MAY BE HARD TO SCOUR THESE
CLOUDS OUT TODAY. BUT...MODEL SOUNDINGS DO SUGGEST THEY WILL
MOSTLY MIX OUT.

WE SHOULD STILL BE ABLE TO MUSTER UP SOME INSTABILITY OVER THE
SOUTHWEST HALF OF THE CWA...BUT FORCING CONTINUES TO BE WEAK AND
ANY STORMS THAT POP WOULD BE VERY ISOLATED...LIKE YESTERDAY. WILL
FOCUS THE SLIGHT CHANCE POPS ALONG THE WEAK SFC CONVERGENCE ZONE
ACROSS THE SOUTHWEST AND KEEP THE NORTHEAST CWA DRY...WHERE TEMPS
WILL BE LOWER.

TEMPS WILL RANGE FROM THE MID 70S AROUND SHEBOYGAN TO THE MID 80S
SOUTHWEST OF MADISON.

TONIGHT SHOULD BE QUIET...BUT STILL WARM. THE MODELS DO SHOW A
MID LEVEL SHORT WAVE MOVING IN FROM THE WEST AND PUSHING OVER THE
TOP OF THE RIDGE...REACHING CENTRAL WI BY AROUND 12Z. WILL CARRY
JUST A SLIGHT CHANCE POP NORTHWEST OF MADISON AFTER 4 AM TONIGHT.
SOME OF THE MODELS LIGHT OFF SOME QPF WITH THIS FEATURE...WHILE
OTHERS REMAIN DRY.

SHORT TERM...SATURDAY THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.

MODELS ARE SHOWING THE 500 MB SHORTWAVE TROUGH OVER LOWER MICHIGAN
WEAKENING AS IT SHIFTS NORTHEAST ON SATURDAY. SOME VORTICITY
MAXIMA FROM THIS FEATURE SLIDES SOUTH SOUTHWESTWARD DURING THE
DAY. LAKE BREEZE DEVELOPING LATER IN THE DAY MAY HELP WITH LOW
LEVEL CONVERGENCE NEAR THE LAKE AS WELL.

GFS AREA FORECAST SOUNDINGS FROM THE GFS SHOWING AROUND 1000 J/KG
MEAN LAYER CAPE WITH WEAK DEEP LAYER SHEAR. NAM SOUNDINGS ARE TOO
HIGH WITH DEW POINTS. GFS PRECIPITABLE WATER VALUES ARE
HIGH...SUGGESTING LOCALLY HEAVY RAINFALL WOULD BE POSSIBLE WITH
ANY STORMS WITH THE WEAK SHEAR.

KEPT SMALL POPS FOR THUNDER GOING SATURDAY IN THE NORTH AND EAST
FOR NOW...THOUGH THERE IS SOME UNCERTAINTY OVER IF THE STORMS
WILL DEVELOP. IT COULD END UP BEING A DRY DAY. ANOTHER WARM AND
HUMID DAY IS EXPECTED...WITH MID TO UPPER 80S FOR HIGHS. LAKE
BREEZE SHOULD COOL THINGS DOWN SOMEWHAT NEAR THE LAKE LATER IN THE
DAY.

WARM AND HUMID AIRMASS WILL LINGER SATURDAY NIGHT INTO SUNDAY
NIGHT...AS 500 MB RIDGE AXIS SLOWLY SHIFTS EAST OF THE AREA. WARM
AND MOIST LOW LEVEL FLOW SHOULD KEEP MID TO UPPER 80S GOING FOR
HIGHS SUNDAY. AGAIN...LAKE BREEZE WILL COOL THINGS DOWN SOMEWHAT
NEAR THE LAKE IN THE AFTERNOON.

NAM MORE AGGRESSIVE THAN GFS WITH FOG DEVELOPING OVER THE AREA
SATURDAY NIGHT AND SUNDAY NIGHT. KEPT FOG OUT OF FORECAST FOR NOW.
DEW POINTS INTO THE 70S WOULD NEED TO DEVELOP DURING THE OVERNIGHT
HOURS ACROSS THE AREA TO SEE DECENT FOG.

COLD FRONT APPROACHES THE AREA FROM THE WEST LATER SUNDAY NIGHT.
MODELS ALL SHOWING DECENT QPF WITH THE APPROACH OF THE FRONT.
FRONTOGENESIS RESPONSE WITH THE FRONT IS NOT VERY STRONG. LAPSE
RATES/DEEP LAYER SHEAR ARE ALSO POOR...WITH NOT MUCH IN THE WAY
OF MEAN LAYER CAPE SUNDAY NIGHT. HIGH PRECIPITABLE WATER VALUES
REMAIN. KEPT LIKELY POPS IN THE WEST AND CENTRAL AREAS SUNDAY
NIGHT...LOWER TO THE EAST.

LONG TERM...MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE IS
MEDIUM.

GFS/ECMWF SHOW THE COLD FRONT MOVING INTO THE AREA
MONDAY...PERHAPS STALLING...CONTINUING THE GOOD CHANCES FOR
SHOWERS AND THUNDERSTORMS. DEEP LAYER SHEAR REMAINS WEAK...WITH
MODEST MEAN LAYER CAPES. KEPT POPS GOING FOR MONDAY...HIGHEST IN
THE EAST.

MODELS THEN GENERALLY SHOW LOW PRESSURE MOVING NORTHEAST FROM THE
CENTRAL PLAINS INTO THE REGION TUESDAY INTO TUESDAY NIGHT...BEFORE
EXITING TO THE EAST ON WEDNESDAY. ANOTHER COLD FRONT PUSHES EAST
THROUGH THE REGION TUESDAY...EXITING THE FAR EAST TUESDAY NIGHT.
GFS/ECMWF SHOWING A 500 MB SHORTWAVE TROUGH MOVING THROUGH THE
REGION TUESDAY INTO TUESDAY NIGHT AS WELL. A DECENT AMOUNT OF QPF
IS SHOWN ON THE MODELS DURING THIS PERIOD. CONTINUED CHANCE POPS
FOR NOW. GFS SOUNDINGS SHOWING BETTER DEEP LAYER SHEAR BUT STILL
LOW END AMOUNTS OF MEAN LAYER CAPE DURING THIS TIME. PRECIPITABLE
WATER VALUES REMAIN ON THE HIGHER END OF THE CLIMATOLOGY SCALE.

HIGH PRESSURE MOVING INTO THE REGION WEDNESDAY INTO THURSDAY
SHOULD BRING QUIET WEATHER...ALONG WITH MUCH COOLER AND DRIER
CONDITIONS.

AVIATION/12Z TAFS/...

VERY DIFFICULT SKY COVER FORECAST...ESPECIALLY THIS MORNING. IFR
CIGS ARE DRIFTING SOUTH DOWN THE LAKE FROM SHEBOYGAN EARLY THIS
MORNING...BUT THEY MAY MAKE IT TO JUST NORTH OF KMKE BEFORE
STALLING. THIS IS SUGGESTED BY A FEW HI RESOLUTION MODELS. IT/S A
VERY CLOSE CALL AND THEY COULD VERY EASILY MAKE IT THROUGH
KMKE/KUES FOR A TIME THIS MORNING.

A BAND OF CLOUDS FARTHER INLAND ARE ASSOCIATED WITH A WEAK LOW
LEVEL TROUGH AND THEY ARE A MIX OF MVFR AND VFR LEVEL CLOUDS.
THESE SHOULD GRADUALLY LIFT AND DISSIPATE TODAY. WOULD EXPECT VFR
CONDITIONS ACROSS ALL OF THE AREA BY LATE MORNING AND THEN
CONTINUE THROUGH THE REMAINDER OF THE TAF PERIOD...BUT UNCERTAINTY
IS SOMEWHAT ELEVATED.

THUNDERSTORM CHANCES TODAY ARE VERY LOW AND MAINLY JUST AN
AFTERNOON SLIGHT CHC FOR KMSN. WINDS WILL BE LESS THAN 10KTS
THROUGH THE TAF PERIOD.

MARINE...

FOG WILL CONTINUE TO BE A THREAT OVER THE NEARSHORE WATERS
THROUGH THE WEEKEND.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...DENSE FOG ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR LMZ644>646.

     DENSE FOG ADVISORY UNTIL 1 PM CDT SATURDAY FOR LMZ643.

&&

$$

UPDATE...HENTZ
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
SATURDAY THROUGH THURSDAY...WOOD


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