Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 290204
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
904 PM CDT THU APR 28 2016

.UPDATE...

JUST STARTING TO SEE THE DIFFERENTIAL CVA-DRIVEN SHOWERS THAT THE
HI-RES MODELS HAVE BEEN DEPICTING FOR LATE THIS EVENING AND
OVERNIGHT BEGINNING TO DEVELOP OVER SW WISCONSIN. THESE SCATTERED
SHOWERS WILL CROSS SOUTHERN WISCONSIN AHEAD OF THE 500 MB LOW THAT
WILL TRACK FROM NEAR LA CROSSE AT 06Z TO AROUND MANITOWOC BY 12Z.
THE BAND OF LONG-LIVED DEFORMATION SHOWERS OVER WEST CENTRAL WI IN
REGION OF 850 MB FRONTOGENESIS EXPECTED TO REMAIN NORTH OF CWA AS
THE LOW CROSSES THE STATE.MADE SOME EARLIER ADJUSTMENTS TO
POPS/WX TO ACCOUNT FOR THE CURRENT RELATIVE LULL IN THE
PRECIPITATION.

DRIER AND COOLER AIR SLOWLY SAGGING INTO SOUTHERN WISCONSIN AS
INVERTED SURFACE TROUGH CONTINUES TO WEAKEN. WILL SEE PATCHY TO
AREAS OF FOG WITH SOME LOCALLY DENSE FOG UNTIL THE DRY AIR FULLY
TAKES HOLD AROUND MID-MORNING FRIDAY.


&&

.AVIATION/06Z TAFS/...

RELATIVE LULL IN RAIN SHOWERS COMING TO AN END WITH SCATTERED
SHOWERS DEVELOPING OVER SOUTH CENTRAL WISCONSIN AHEAD OF MID-
LEVEL LOW THAT WILL CROSS CENTRAL WISCONSIN OVERNIGHT. IFR CIGS
ARE SLOWLY LIFTING FROM NE TO SOUTHWEST AS DRIER AIR SLOWLY MOVING
IN AS INVERTED SURFACE TROUGH WEAKENS/COLLAPSES. EXPECT MAINLY
MVFR CIGS AND VSBYS WITH PATCHY FOG AND THE SCATTERED
SHOWERS/PATCHY DRIZZLE UNTIL MID-LEVEL WAVE MOVES OFF TO THE EAST
BY EARLY FRIDAY MORNING.

21Z SREF PROBABILITY OF CIGS BELOW 3K FEET MORE OPTIMISTIC THAN
12Z NAM MOS GUIDANCE ABOUT LIFTING CIGS TO VFR LEVELS BY EARLY TO
MID AFTERNOON FRIDAY...CLOSER TO 12Z GFS MOS. WILL AWAIT COMPLETE
LOOK AT 00Z DATA BUT INDICATIONS ARE THAT DRIER AIR SHOULD SPREAD
IN SUFFICIENTLY TO SUPPORT THE GFS/SREF SOLUTION.

&&

.MARINE...

SURFACE PRESSURE GRADIENT CONTINUES TO WEAKEN AS SURFACE TROUGH
COLLAPSES/DROPS SOUTHEAST. THIS ALLOWED NORTHEAST WINDS TO WEAKEN
AND WAVES TO SUBSIDE TO ALLOW SMALL CRAFT ADVISORY TO EXPIRE
EARLIER THIS EVENING.

WINDS AND WAVES WILL REMAIN BELOW ADVISORY LEVELS UNTIL SATURDAY
WHEN WINDS INCREASE WITH THE APPROACH OF LOW PRESSURE FROM THE
CENTRAL PLAINS...WITH SMALL CRAFT ADVISORY CONDITIONS EXPECTED
THROUGH SUNDAY AS THE LOW TRACKS ACROSS SOUTHERN ILLINOIS AND
ALONG THE OHIO RIVER VALLEY

&&

.PREV DISCUSSION... /ISSUED 335 PM CDT THU APR 28 2016/

SHORT TERM...

TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM.

REMNANTS OF UPPER LOW ACRS SRN MN WILL TRANSLATE ACRS SRN WI TNGT
WITH MORE SHRA CHCS. MESO MODELS SHOW AN UPTICK LATER THIS EVE INTO
THE POST MIDNIGHT HOURS AND THEN DIMINISH TOWARDS MORNING. CLOUD
COVER WILL HANG TOUGH ALL NIGHT AND QUESTION BECOMES HOW QUICK
THINGS CLEAR OUT ON FRIDAY WITH UPPER SYSTEM AND SFC LOW OFF TO OUR
EAST. LLVL RH PROGS LOOK A BIT MORE PESSIMISTIC WITH QUITE A BIT OF
80 PCT RH LINGERING INTO THE AFTERNOON. GFS MOS HINTING AT SOME SUN.
TOOK A LOOK AT THE NAM SOUNDINGS FROM BUFKIT AND IT DOES SHOW THE
DEPTH OF SATURATION DIMINISHING DURING THE AFTERNOON WHICH SHOULD
ALLOW FOR AT LEAST SOME SCT-BKN CONDITIONS TO DEVELOP. THE MORE
OPTIMISTIC LOOKING GFS SHOWS MUCH MORE SUN ESP IN THE NE CWA WITH
POSSIBLY SOME SUN EVOLVING IN KMSN AREA AS WELL DURING THE
AFTERNOON. TEMPS WILL BE EVER SO DEPENDENT ON THAT SUNSHINE TAKING
SHAPE THOUGH ONSHORE FLOW FOR CERTAIN TO KEEP THINGS ON THE COOL
SIDE IN THE EAST/NEAR THE LAKE.

FRIDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM.

ANOTHER LARGE UPPER LOW WILL MOVE INTO THE CENTRAL GREAT PLAINS
FOR FRI NT AND SAT WHILE ANOTHER UPPER LOW MOVES SEWD ACROSS
ONTARIO CANADA. THE INTERACTION BETWEEN THE TWO WILL BE A FACTOR
IN THE OVERALL NWD MOVEMENT OF THE PLAINS SYSTEM...AS WELL AS THE
DEGREE OF CYCLOGENESIS THAT OCCURS WITH THE PLAINS SYSTEM. THE
MODELS DO NOT AGREE ON THE EVOLUTION OF THE LOW PRESSURE AREAS AND
RESULTANT RAIN CHANCES FOR THE WEEKEND. THE GFS KEEPS THE PLAINS
SYSTEM TO THE SOUTH WITH NO RAIN AT ALL...WHILE THE ECMWF IS THE
MOST AGGRESSIVE WITH THE RAIN OVERSPREADING SRN WI. THE NAM AND
CANADIAN ARE A BIT OF A COMPROMISE BUT LEANING MORE TOWARD THE
ECMWF AND THAN THE NAM.

WILL BASE THE FCST OFF THIS SCENARIO. THE SFC LOW OVER THE TX
PANHANDLE WILL EVOLVE TO A BROAD W-E SFC TROUGH AS IT MOVES ENEWD
ACROSS THE OHIO RIVER VALLEY. A LOBE OF PVA AND 850-700 MB WARM
ADVECTION/FRONTOGENESIS WILL BRING A W-E BAND OF RAIN TO THE SRN
HALF OF THE CWA FOR SAT AFT AND LINGER INTO SAT NT. CENTRAL WI MAY
NOT SEE ANY RAIN AT ALL WITH DRY NELY WINDS UNDERCUTTING THE WEAK
MID LEVEL LIFT AND MOISTURE. DRY AIR WILL GRADUALLY ADVECT INTO
THE REGION ON SUN BUT STILL HUNG ONTO SLIGHT CHANCES IN THE SRN
CWA AS THE UPPER LOW OPENS UP INTO A MORE PROGRESSIVE WAVE AND
COULD BRING A FEW SHOWERS TO FAR SRN WI. THE CLOUDS AND RAIN
CHANCES WILL KEEP THE DAYTIME HIGH TEMPS RELATIVELY COOL FOR THE
WEEKEND. HIGH PRESSURE TO BUILD OVER THE REGION FOR SUN NT AND
MON.

LONG TERM...TUESDAY THROUGH THURSDAY...FORECAST CONFIDENCE
MEDIUM.

A WEAK UPPER TROUGH WILL PASS TUE AND TUE NT. A NLY FLOW ALOFT
WILL THEN BECOME ESTABLISHED FOR THE MIDDLE OF THE WEEK AS A
BRIEF OMEGA BLOCK MAY DEVELOP. THE HIGH AMP RIDGE OF THE OMEGA
BLOCK WILL BUILD OVER THE HIGH PLAINS. SMALL CHANCES OF SHOWERS
ARE FORECAST AT TIMES WITH TEMPS REASONABLY CLOSE TO NORMAL.

AVIATION/00Z TAFS/...WATER VAPOR/RAP ANALYSIS SHOWS PRONOUNCED
CIRCULATION CENTER ACRS SRN MN. SFC LOW/OCCLUDED BOUNDARY CONTINUES
TO DRIFT ESE FROM IA/CNTRL IL INTO SRN IN. 500 LOW PROGGD TO SHIFT
EWD ACRS SRN WI TNGT. SO EXPECT SHRA CHCS TO REMAIN THROUGH THE
NIGHT AND DRY OFF QUICKLY BY FRI MRNG. MOIST ENE FLOW TO PERSIST
WITH WIDESPREAD STRATUS. SOME IFR/LIFR CIGS HAVE ALREADY TAKEN SHAPE
IN PARTS OF ERN WI AND EXPECT THIS TREND TO CONTINUE. WOULD EXPECT
SOME IMPROVEMENT IN CIG HGTS ON FRI AS SOME DRIER AIR SETTLES ACROSS
THE AREA. STILL SOME UNCERTAINTY ON HOW QUICKLY THE EXTENSIVE CLOUD
SHIELD WILL CLEAR OUT AS THE DAY WEARS ON FRIDAY.

MARINE...WINDS AND WAVES WILL REMAIN ELEVATED AS PRESSURE GRADIENT
TAKING A BIT LONGER TO EASE. HAVE THUS RE-ISSUED THE SMALL CRAFT
ADVISORY TO GO UNTIL 6 PM TO COVER SOME OF THESE HIGHER GUSTS/WAVE
ACTION THAT HAVE BEEN OBSERVED...ESPECIALLY FROM NEAR PORT
WASHINGTON NORTHWARD TO SHEBOYGAN AREA.

&&

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

$$

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



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