Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 240211
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
911 PM CDT THU JUL 23 2015

.UPDATE...

NO SIGNIFICANT CHANGES TO GOING FORECAST...THOUGH DID LOWER LOW
TEMPERATURES A FEW DEGREES BASED ON CLEAR...CALM CONDITIONS AND
TREND THE PAST FEW NIGHTS OF LOWS CLOSE TO THE VALUES OF DEW
POINTS AT TIME OF THE AFTERNOON MAX TEMP....WHICH RANGED FROM 54F
TO 61F. LOOKING FOR FOG IN THE WISCONSIN RIVER VALLEY...WITH SOME
PATCHY GROUND FOG IN LOW-LYING LOCATIONS ELSEWHERE IN THE FORECAST
AREA.

HI-RES RAPID UPDATE MODELS STILL KEEPING MCS CURRENTLY
DEVELOPING IN NORTH DAKOTA TO THE WEST OF THE FORECAST AREA
THROUGH 15Z FRIDAY.

&&

.AVIATION/06Z TAFS/...

LOOKING AT SIMILAR VFR CONDITIONS OVERNIGHT AS THE PAST FEW
NIGHTS...WITH CLEAR SKIES AND LIGHT WINDS LEADING TO FOG IN THE
WISCONSIN RIVER VALLEY AND PATCHY GROUND FOG DURING THE LAST FEW
HOURS BEFORE SUNRISE IN LOW-LYING AREAS ELSEWHERE. AGAIN...THE
PROBABILITY AND AREAL COVERAGE ARE TOO LOW TO PUT INTO THE
TAFS...BUT COULD SEE AN HOUR OR TWO OF MVFR GROUND FOG AT ANY OF
THE TAF SITES.

LATEST NAM RUN IN GENERAL AGREEMENT WITH PREVIOUS CONSENSUS TIMING
OF SHOWERS AND THUNDERSTORMS...HOLDING THEM WEST OF KMSN THROUGH
00Z SATURDAY...THEN CROSSING ALL OF SOUTHERN WISCONSIN OVERNIGHT
WITH THE PASSAGE OF THE COLD FRONT/SURFACE TROUGH WITH HIGHEST
CHANCE BETWEEN 06Z AND 12Z. THOUGHT OF CARRYING VICINITY
THUNDERSTORMS AT KMSN BETWEEN 03Z AND 06Z...AND AT KMKE AFTER
06Z...BUT PRECIPITATION PROBABILITY IN CHANCE CATEGORY SO WILL
LEAVE OUT FOR NOW. VFR CONDITIONS THROUGH THE DAY...LOWERING TO
MVFR WITH SHOWERS AND STORMS OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 334 PM CDT THU JUL 23 2015/

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

RIDGING ALOFT AND HIGH PRESSURE AT THE SURFACE WILL KEEP THINGS
QUIET THIS EVENING AND OVERNIGHT. CLEAR SKIES COMBINED WITH CALM
WINDS OVERNIGHT SHOULD COMBINE TO ALLOW TEMPERATURES TO DROP INTO
THE LOW 60S. 925 TEMPS SUGGEST LOWS COULD DIP EVEN LOWER...BUT GIVEN
THAT MOST GUIDANCE SUGGESTS LOW TO MID 60S...AND FOR COLLABORATION
PURPOSES...WAS NOT COMFORTABLE DROPPING ANY LOWER. CURRENTLY
EXPECTING TO SEE SOME FOG IN THE TYPICAL LOW LYING AREAS...BUT IF
TEMPS SHOULD DROP LOWER THAN EXPECTED...WE MAY SEE MORE WIDESPREAD
FOG ACROSS THE FORECAST AREA.

FRIDAY...FORECAST CONFIDENCE IS MEDIUM.

A JET STREAK WILL IMPINGE INTO NORTHERN WISCONSIN WHILE A 500 MB
SHORT WAVE/VORT MAX CROSSES THE SAME AREA. THIS WILL BRING A ROUND
OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL
PORTIONS OF THE STATE. MOST GUIDANCE KEEPS PRECIP TO THE NORTH AND
WEST OF THE FORECAST AREA. HOWEVER...DUE TO CONSIDERABLE 700 MB WAA
COUPLED WITH MOISTURE AT THE H700 AND H850 LEVELS...ENDED UP GOING
WITH SLIGHT CHANCE THUNDER IN THE FAR NORTHWESTERN PORTIONS OF THE
FORECAST AREA THROUGHOUT THE DAY.

FRIDAY NIGHT - CONFIDENCE...MEDIUM
LOW LEVEL TROUGH PASSAGE EXPECTED THIS PERIOD AS LOW PRESSURE
SHIFTS EAST OF LAKE SUPERIOR. MID LEVEL FLOW LOSES ANTICYCLONIC
LOOK AND SOME INCREASE IN WNW 500 WINDS EXPECTED WITH PRIMARY
SHORTWAVE TRAVERSING AREAS TO OUR NORTH. INSTABILITY MAY END UP
BEING OF THE ELEVATED VARIETY BY THE TIME BETTER FORCING ARRIVES.
ALL MODELS SHOWING AT LEAST SOME CONVECTION SURVIVING INTO SRN WI
SO WILL KEEP CHANCE POPS GOING.

SATURDAY - CONFIDENCE...MEDIUM
SURFACE BOUNDARY LIKELY TO END UP SOUTH OF WI WITH HIGH PRES
GRADUALLY NOSING INTO SRN WI. THE TREND HAS BEEN TO SHIFT THE QPF
INTO IL SO HAVE ELECTED TO GO WITH CONSENSUS OF BOTH THE NAM AND
GFS MOS SINGLE DIGIT POPS AND KEEP PRECIP MENTION OUT OF FORECAST.
925 TEMPS ACTUALLY WARMER THAN FRI AHEAD OF THE TROUGH SO WILL
KEEP TEMPS WELL INTO THE 80S WITH SOME COOLER TEMPS LAKESIDE WITH
THE ONSHORE FLOW.

SUNDAY - CONFIDENCE...LOW
BRIEF MID LEVEL RIDGING THAT EVOLVES SATURDAY NIGHT GIVES WAY TO
APPROACHING SHORTWAVE. TIMING AND STRENGTH OF THIS WAVE IS
DEPICTED DIFFERENTLY BY THE MODELS. AS A RESULT WE HAVE 2 DRY AND
2 WET MODELS. WILL GO WITH THE SUPERBLEND POPS AT THIS TIME. THE
LATEST GEM AND GFS ARE PRETTY AGGRESSIVE WHILE THE 12Z NAM SHOWS
PRECIP STAYING TO OUR WEST AND THE 00Z ECMWF WAS SLOW TO BRING
PRECIP IN WITH THE HIGH STILL IN CONTROL.

SUNDAY NIGHT THROUGH MONDAY NIGHT - CONFIDENCE...LOW
THE GFS SHOWS A SWATH OF NW/SE ORIENTED CONVECTION ASSOCIATED
WITH THE NOSE OF THE HOT AIRMASS THIS PERIOD. MEANWHILE THE ECMWF
IS SHOWING LOW LEVEL ANTICYCLONIC REGIME WITH THERMAL TROUGH
LINGERING.

TUESDAY - CONFIDENCE...LOW
591DM 500 MILLIBAR RIDGE BUILDS FURTHER INTO WI. GFS SHOWS 925
TEMPS PUSHING 30C WITH CONVECTION WELL OFF TO THE NORTHEAST.
MEANWHILE ECMWF SHOWS POTENTIAL CLOUDIER AND COOLER REGIME WITH
CONVECTION ARRIVING LATER IN THE DAY/EVENING ASSOCIATED WITH THAT
MODELS PUSH OF A WARMER AIRMASS. SHOULD GFS VERIFY WE WILL NEED
TO EVENTUALLY BOOST HIGHS INTO THE 90S WITH POTENTIAL HEAT
ADVISORY CRITERIA BEING MET.

TUESDAY NIGHT AND WEDNESDAY - CONFIDENCE...MEDIUM
FRONTAL BOUNDARY PROGGD TO DRAW CLOSER WITH TIMING DIFFERENCES
WITH CONVECTION...THOUGH SOME CONSENSUS CONVECTION WOULD CLEAR CWA
BY LATER WEDNESDAY.

WEDNESDAY NIGHT AND THURSDAY - CONFIDENCE...MEDIUM
FRONTAL BOUNDARY SHIFTS TO THE EAST/SOUTHEAST WITH WINDS SHIFTING
NW AND A MORE PRONOUNCED COOLING SIGNAL ON THE ECMWF.

AVIATION/00Z TAFS/...VFR CONDITIONS ARE EXPECTED THROUGH THE EVENING
AND OVERNIGHT HOURS THANKS TO HIGH PRESSURE ACROSS THE FORECAST
AREA. HOWEVER THERE IS A CHANCE OF SOME IFR FOG IN THE TYPICAL LOW
LYING AREAS. ADDITIONALLY...925 MB TEMPS SUGGEST LOWS MAY DROP A
BIT LOWER THAN CURRENTLY FORECAST. IF THIS HAPPENS...FOG MAY BE
MORE WIDESPREAD THAN EXPECTED.

ON FRIDAY...A LOW PRESSURE SYSTEM WILL TRACK ACROSS NORTHERN
WISCONSIN BRINGING HIGH AND MID CLOUDS TO ALL TAF SITES. ANY PRECIP
OR REDUCED CIGS SHOULD HOLD OFF UNTIL FRIDAY EVENING...SO EXPECTING
VFR CONDITIONS THROUGH THE DAY.

MARINE...WHILE WAVES HEIGHTS WILL STRUGGLE REACH 2 FEET...SOUTHWESTERLY
WINDS FROM 10-15 KNOTS...GUSTING UP TO 20 KNOTS...MAY MAKE FOR MARGINALLY
HAZARDOUS CONDITIONS FOR SMALL CRAFTS. THAT SAID...NO SMALL CRAFT
ADVISORY IS EXPECTED DUE TO THE LOW WAVE HEIGHTS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$

UPDATE...REM
TONIGHT/FRIDAY AND AVIATION/MARINE...BSH
FRIDAY NIGHT THROUGH THURSDAY...COLLAR



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