AP-IL--MKE-IL Area Forecast Discussion, IL
000
FXUS63 KMKX 151521
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1021 AM CDT WED JUL 15 2015
.AVIATION/18Z TAFS/...VFR CONDITIONS TODAY INTO MUCH OF THE NIGHT
WITH DRY/STABLE INFLUENCE OF SURFACE HIGH. EXPECT AN INCREASE IN
MID LEVEL CLOUDS AS THE NIGHT WEARS ON WITH LATEST RAP SOUNDINGS
SHOW LOW LEVELS REMAINING QUITE DRY. IMPRESSIVE LLJ TAKES AIM AT
SRN WI FOR THURSDAY WITH DECENT THERMAL/MOIST ADVECTION EXPECTED.
SO HIGH POPS LOOK GOOD. SREF MVFR CIG PROBS SHOW GREATEST
LIKELIHOOD OF MVFR/IFR CONDITIONS ACRS NRN WI ON THURSDAY.
PC
&&
.PREV DISCUSSION... /ISSUED 359 AM CDT WED JUL 15 2015/
TODAY...FORECAST CONFIDENCE IS HIGH.
KEEPING EYE ON LOW CLOUDS MOVING WWD ACROSS LAKE FROM LOWER MI.
APPEARS DECREASING TREND SHOWING UP ON LATEST IR IMAGERY. LOW
CLOUDS NOT INDUCED BY LAKE EFFECT DUE TO MINIMAL DELTA T
DIFFERENCE. CLOUDS ALSO RUNNING INTO DRIER AIR AND SUBSIDENCE OVER
SRN WI. AFTER PATCHY EARLY MORNING CLOUDS IN THE SOUTHEAST...STILL
EXPECTING A VERY PLEASANT DAY UNDER LOTS OF SUNSHINE WITH SOME
PASSING MID TO HIGH CLOUDS LATER THIS MRNG AND AFTN.
NORTHEAST BREEZES WL CONTRIBUTE TO TEMPERATURES REMAINING BELOW
NORMAL TODAY. WARMEST TEMPS IN FAR WEST WHERE KLNR WL MOST LIKELY
CRACK 80.
TONIGHT...FORECAST CONFIDENCE IS HIGH.
A QUIET NIGHT IS EXPECTED MOST AREAS AS SHORT WAVE RIDGING SLIDES
OFF TO THE EAST. DRY AIR AND LIGHT WINDS WILL ALLOW TEMPERATURES
TO FALL RAPIDLY DURING THE EVENING. HOWEVER EXPECT INCREASING MID
TO HIGH CLOUDS LATER IN THE EVENING AND OVERNIGHT AS UPSTREAM LOW
LEVEL JET FOCUSES ON IA/MN. SOUTHWEST WI GETS CLIPPED BY
INCREASING MID LEVEL MOISTURE AND SURGE OF 700MB WARM AIR
ADVECTION. MAY BE JUST ENOUGH MID LEVEL INSTABILITY FOR ISOLD
-SHRA/-TSRA TO DEVELOP LATE TNGT ACROSS FAR WRN CWA WITH BULK OF
PRECIPITATION OCCURRING ON THURSDAY.
SHORT TERM...THURSDAY THROUGH FRIDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.
MODELS ARE STILL SHOWING SOME VARIATION IN TIMING AND PLACEMENT OF
FEATURES FOR THURSDAY INTO THURSDAY NIGHT. THE NAM AND CANADIAN
MODELS CONTINUE TO BRING WEAK LOW PRESSURE AND A WARM FRONT
NORTHEASTWARD TOWARD AND ACROSS CENTRAL/NORTHEAST WISCONSIN
DURING THIS PERIOD. THE GFS HAS TRENDED FURTHER NORTHWARD WITH
THESE FEATURES...SIMILAR TO THE NAM/CANADIAN. THE ECMWF CONTINUES
TO BE THE FURTHEST SOUTH WITH THESE FEATURES...NORTHEASTWARD INTO
AND ACROSS SOUTHERN WISCONSIN.
ALL MODELS SHOW A GOOD AMOUNT OF FOCUSED WARM AIR ADVECTION ACROSS
THE AREA THURSDAY INTO THURSDAY NIGHT. THE BEST FRONTOGENESIS
RESPONSE FIELDS REMAIN NORTH/NORTHWEST OF THE AREA...ALONG WITH
THE NOSE OF THE SOUTH SOUTHWESTERLY LOW LEVEL JET. THE MAIN 500 MB
VORTICITY MAXIMUM MOVES THROUGH THE REGION ON THURSDAY...FOCUSING
ON NORTHERN WISCONSIN...EXCEPT THE ECMWF WHICH BRINGS IT THROUGH
SOUTHERN WISCONSIN.
CONTINUED TREND OF BRINGING LIKELY POPS EASTWARD INTO THE AREA
THURSDAY...LINGERING THURSDAY NIGHT. SPC EXPANDED THE MARGINAL
RISK FOR SEVERE STORMS INTO SOUTH CENTRAL WISCONSIN. THERE IS
ENOUGH ELEVATED CAPE LATER THURSDAY INTO THURSDAY NIGHT WITH
MARGINAL DEEP LAYER SHEAR THAT WOULD SUPPORT ISOLATED SEVERE
HAIL. ECMWF HAS MUCH LOWER CAPE VALUES THAN NAM/GFS...SO WENT
BETWEEN THESE FOR CAPE ESTIMATES. HIGH PRECIPITABLE WATER VALUES
AS WELL...SO SOME HEAVY RAINFALL COULD OCCUR.
KEPT CHANCE POPS FOR SHOWERS AND STORMS FRIDAY AND FRIDAY NIGHT
ACROSS THE AREA...AS SURFACE TROUGH/STATIONARY FRONT LINGERS WEST
TO EAST. NAM/ECMWF SHOWING A POSSIBLE MCS TRYING TO MOVE ALONG IT
TOWARD THE AREA FRIDAY NIGHT. THE OTHER MODELS HINT AT QPF ALONG
THE BOUNDARY AT VARIOUS TIMES DURING THIS PERIOD.
AGAIN...WENT BETWEEN HIGH CAPES ON NAM/GFS AND LOWER VALUES ON
ECMWF DURING THIS TIME. DEEP LAYER SHEAR IS MODEST AT BEST...WITH
DECENT PRECIPITABLE WATER VALUES. BEST SHOT AT ANY SEVERE WEATHER
WOULD BE WITH MCS MOVING TOWARD THE AREA LATER FRIDAY NIGHT.
VERY WARM AND HUMID DAY IS EXPECTED FRIDAY...WITH SOUTHWEST WINDS
BRINGING MID TO UPPER 80S ACROSS THE AREA. DEW POINTS SHOULD RISE
INTO THE UPPER 60S TO LOWER 70S AS WELL.
LONG TERM...SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE IS
MEDIUM.
GFS/ECMWF CONTINUE TO SHOW SOME DIFFERENCES WITH TIMING AND
PLACEMENT OF FEATURES DURING THIS PERIOD. ECMWF TRIES TO BRING
POSSIBLE WEAKENING MCS THROUGH THE AREA SATURDAY MORNING...KEEPING
BOUNDARY NEARBY IN THE AFTERNOON. IT BRINGS A COLD FRONT SOUTHEAST
THROUGH THE AREA SUNDAY WITH DECENT QPF VALUES.
THE GFS HAS THE BOUNDARY FURTHER NORTH...WITH THE COLD FRONT
SLIDING THROUGH MAINLY SUNDAY NIGHT WITH GOOD QPF VALUES.
CONTINUED POPS FOR SHOWERS AND THUNDERSTORMS SATURDAY INTO SUNDAY
NIGHT. MODIFIED CAPES AND MODEST AT BEST DEEP LAYER SHEAR SUGGEST
RELATIVELY LOW SEVERE RISK AT THIS TIME.
VERY WARM AND HUMID CONDITIONS CONTINUE SATURDAY AND SUNDAY...THOUGH
LAKE BREEZE SATURDAY SHOULD COOL THINGS DOWN NEAR THE LAKE. HEAT
INDEX VALUES MAY REACH THE MID 90S DURING THIS TIME INLAND.
THERE MAY BE A LULL IN ANY PRECIPITATION ACTIVITY MONDAY INTO
TUESDAY...WITH COOLER AND DRIER AIR WORKING INTO THE REGION. KEPT
CONSENSUS BLEND OF POPS AND TEMPERATURES FOR THIS PERIOD...BUT MAY
HAVE TO GO DRIER IN LATER FORECASTS IF THIS TREND PERSISTS.
AVIATION/12Z TAFS/...
WEAK LOW LEVEL CONVERGENCE OVER SRN LOWER MI AND LAKE MI CARRYING
SOME STRATUS INTO PORTIONS OF THE WI LAKESHORE EARLY THIS MORNING.
UNFORTUNATELY...PATCHY HIGH CLOUDS CURRENTLY OBSCURING TRENDS OVER
PAST HOUR OR SO...BUT SLIGHT DECREASING TREND NOTED IN LAST
SEVERAL 11-3.9 MICRON IMAGES.
STILL...LATEST IMAGE SHOWS LOW CLOUDS KNOCKING ON DOORSTEP OF
KMKE AND KENW SO INTRODUCED IN LATEST UPDATE. WOULD EXPECT THESE
LOW CLOUDS WOULD THIN RAPIDLY EARLY THIS MORNING AS DRIER AIR AND
BUILDING SUBSIDENCE ERODE LOW CLOUDS. OTRW A VFR PERIOD WITH
THICKENING CLOUDS LATER TONIGHT DUE TO UPSTREAM SURGE OF LOW LEVEL
MOISTURE AND WARM AIR.
MARINE...
WINDS REMAINING GUSTY ACROSS SOUTHERN MARINE ZONES EARLY THIS
MORNING. STATIONARY VESSEL IN RACINE HARBOR REPORTING SUSTAINED NE
WINDS OF 13KTS WHILE FARTHER SOUTH...NE WINDS STILL GUSTING TO
26KTS AT KNSW3. FARTHER NORTH...WEAKENING PRESSURE GRADIENT AND
SURGE OF COLD AIR HAS ALLOWED WINDS TO SUBSIDE TO MOSTLY 10 TO
18KTS.
THIS DIMINISHING TREND WI AFFECT SOUTHERN LAKE MI ZONES EARLY
THIS MORNING...BUT EXPECT WINDS TO REMAIN GUSTY ACROSS SRN LAKE MI
ZONE THROUGH 12Z OR SO. HENCE WL EXTEND SMALL CRAFT ADVY IN LMZ646
BUT CANCEL ELSEWHERE.
BEACHES...
WILL LET BEACH HAZARD STATEMENT EXPIRE AT 09Z. WINDS HAVE
DECREASED TO BELOW 15 KNOTS NORTH OF WIND POINT LIGHT OVERNIGHT
DUE TO WEAKENING PRESSURE GRADIENT AND WEAKENING PUSH OF LOW LEVEL
COLD AIR. WINDS REMAIN GUSTY SOUTH OF WIND POINT ACROSS RACINE AND
KENOSHA BEACHES AS WAVE HEIGHTS STILL IN THE 3 TO 5 FT RANGE.
HOWEVER EXPECT WINDS AND WAVES TO SUBSIDE THROUGH 8 AM SO DO NOT
SEE THE NEED TO EXTEND BEACH HAZARD STATEMENT AT THIS TIME. MOST
SWIMMERS WOULD BE HEADING TO THE BEACH LATER THIS MORNING AND AFTN
WHEN WINDS AND WAVES WILL BE SIGNIFICANTLY LOWER.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...MBK
THURSDAY THROUGH TUESDAY...WOOD
Delivered by Weather Underground Inc. Wed Jul 15 2015 11:22AM EDT