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000
FXUS63 KMKX 180820
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
320 AM CDT SAT MAY 18 2013

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM TO HIGH.

MID LEVEL CLOUDS HAVE EXPANDED OVERNIGHT IN MOIST...COOL NORTHEAST
FLOW.  PATCHY LOW CLOUDS HAVE ALSO DEVELOPED NEAR LAKE MICHIGAN AS
OPPOSED TO FOG DUE TO BOUNDARY LAYER MIXING. CLOUDS SHOULD ERODE
FROM SOUTH TO NORTH THROUGH THE MORNING AND MAY HANG ON INTO THE
AFTERNOON. IN ADDITION...CIRRUS FROM UPSTREAM CONVECTION SHOULD
CONTINUE TO SPREAD EAST TO SOUTHEAST AND AFFECT THE AREA FOR A TIME.
HENCE CAN NOT BE TOO OPTIMISTIC WITH SUNSHINE FOR TODAY.  ELY FLOW WL
ALSO KEEP DAYTIME TEMPERATURES IN CHECK...ESPECIALLY VCNTY OF LAKE
MI.

HRRR AND 4KM WRF-NAM CONTINUE TO SHOW SMALL THREAT FOR LATE MRNG AND
AFTN ISOLD CONVECTION IN WRN CWA.  DEWPTS COULD POP BACK UP INTO THE
UPPER 50S TO AROUND 60 IN THE WESTERN CWA...RESULTING IN WEAK
ELEVATED INSTABILITY AS WEAK MID LEVEL WAVE PASSES BY.  HENCE WL
CONTINUE TO MENTION SCHC POPS IN THIS AREA.

QUIET NIGHT TONIGHT BUT WL NEED TO WATCH FOR FOG POTENTIAL AS
BOUNDARY LAYER WINDS SHOULD BE A BIT LIGHTER.  WL DEPEND ON CLOUD
COVER.  TOO MUCH UNCERTAINTY AT THIS POINT TO INCLUDE IN FORECAST.

RECENT TAMDAR SOUNDINGS FROM NRN IL CONFIRM LIGHTER 85H VS REGIONAL
WIND PROFILERS...POSSIBLY DUE TO BIRD CONTAMINATION.

SUNDAY AND SUNDAY NIGHT - CONFIDENCE...MEDIUM
PRIMARY 500 MILLIBAR SHORTWAVE LIFTS NORTHEAST FROM THE CENTRAL
PLAINS. BEST VORTICITY ADVECTION AND FORCING FROM LOW LEVEL JET
REMAINS TO THE WEST OF THE AREA FOR MUCH OF THE DAY. AREAS WEST OF
MADISON HAVE BEST CHANCE OF SEEING SHRA/TSRA ARRIVE IN CONJUNCTION
WITH THE H8 LLJ AND H5 PIVA. WITH BOTH THE TRANSLATION OF THE LLJ
AND APPROACH OF UPPER WAVE...FORCING INCREASES SUNDAY NIGHT WITH
BETTER CHANCES OF TSRA CWA WIDE.

MONDAY AND MONDAY NIGHT - CONFIDENCE...MEDIUM
MODELS IN DECENT AGREEMENT IN PIVOTING POTENT DYNAMICS INTO SRN WI
AROUND MAIN UPPER LOW CENTER NEAR KFSD. WAVE THAT SWINGS IN DURING
18Z AND 00Z HAS NEGATIVE TILT LOOK AND PROGGD TO ENCOUNTER FAVORABLE
THERMODYNAMICS. STILL SEEING LI/S AROUND -12 IN WESTERN CWA BUT
PLENTY OF INSTABILITY CWA WIDE. SURFACE MOISTURE SHOULD BE AMPLE
WITH DEW POINTS IN THE 60S. 250 MILLIBAR JETLET TAKES AIM ON THE CWA
DURING THE AFTERNOON/EVENING AS WELL. CWASP SHOWING VERY STRONG
SIGNALS WITH READINGS IN THE MID 70S TO MID 80S. GFS AND NAM CAPES
RISE TO BETWEEN 1500 AND 2500 J/KG WHICH COULD BE REALIZED WITH THE
DEPARTURE OF ANY LINGERING CLOUD COVER FROM THE MORNING CONVECTION.
0-6KM AND 0-1 SHEAR IS AMPLE WITH MID LEVEL LAPSE RATES/700-500 MB/
EXCEEDING 8C/KM. ALL IN ALL SLIGHT RISK FROM SPC LOOKS QUITE
WARRANTED.

TUESDAY AND WEDNESDAY - CONFIDENCE...MEDIUM
UPPER PATTERN SLOW TO MOVE...WITH MORE OF AN EASTWARD NUDGE ON
WEDNESDAY. DECENT SOUTHWEST 500 MILLIBAR FLOW INTO SRN WI AROUND
UPPER LOW IN SW MN OR ERN SD. 00Z ECMWF STILL QUICK TO DROP SURFACE
BOUNDARY INTO NRN IL WHILE OTHER MODELS LINGER IT ACROSS SRN OR
CNTRL WI. PRIOR CONVECTIVE TRENDS WILL DICTATE WHERE LOW LEVEL
BOUNDARIES SET UP. ENOUGH 500 MILLIBAR ENERGY AND FORCING VIA
SURFACE/850 BOUNDARIES TO KEEP LIKELIHOOD OF TSRA IN FORECAST.

THURSDAY - CONFIDENCE...MEDIUM
NORTHEAST SURFACE/850 MILLIBAR FLOW DEVELOPS SLOWER ON THE ECMWF
THAN THE GFS. LINGERING CYCLONIC FLOW WILL KEEP SHRA CHANCES IN
PLACE. 850 TEMPS DROP TO 5 OR 6C.

FRIDAY - CONFIDENCE...MEDIUM
GFS AND ECMWF BOTH SHOW HIGH PRESSURE BUILDING IN WHICH WILL BRING A
MUCH NEEDED DRY DAY...ALBEIT ON THE COOL SIDE.

&&

.AVIATION/12Z TAFS/...BOUNDARY LAYER MIXING AND MOIST LOW TO MID LEVELS
HAS ALLOWED PATCHY LOW CLOUDS TO DEVELOP BY LAKE MI LAST HOUR. WL
LIKELY CONTINUE FOR SEVERAL MORE HOURS AND MAY EXPAND FARTHER
WEST...BUT LOW LEVEL CONVERGENCE WL DIMINISH AS WINDS BEGIN TO
VEER THROUGH THE EARLY MRNG. HENCE WL RETURN TO VFR CONDITIONS BY
MID-MORNING. SOME LIGHT FOG MAY ACCOMPANY LOW CLOUDS BUT BOUNDARY
LAYER MIXING SHOULD PREVENT MORE SIGNIFICANT FOG. FOG MAY BE MORE
PREVALENT TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING BUT TOO MUCH
UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN MVFR VSBYS
AT THIS POINT.

&&

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

$$
TODAY/TONIGHT AND AVIATION/MARINE...MBK
SUNDAY THROUGH FRIDAY...COLLAR