Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 260157
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
857 PM CDT WED MAR 25 2015

.UPDATE...
MUCH OF THE GUIDANCE HAD BEEN VERY OPTIMISTIC THAT THE LOW
CLOUDS...WHICH CLEARED OUT EARLIER...WOULD STAY OUT.
BUT...THEY/RE MOVING BACK IN FROM THE WEST WITH THE APPROACH OF
A MID LEVEL SHORTWAVE. OTHER THAN THE CLOUD COVER
UNCERTAINTIES...IT/S A PRETTY QUIET NIGHT OUT THERE WITH LITTLE
CHANGE TO THE FORECAST NEEDED.

&&

.AVIATION/06Z TAFS/...
IT LOOKS LIKE THE MVFR CLOUDS ARE MOVING BACK IN FROM THE
NORTHWEST. CONFIDENCE ISN/T VERY HIGH ON WHAT THE TRENDS WILL BE
OVERNIGHT AS MOST OF OUR SHORT RANGE LOW LEVEL RH GUIDANCE HAS
THIS STUFF CLEARED OUT RIGHT NOW. THERE DOES APPEAR TO BE SOME
DRYING WORKING INTO SE MN AND THIS WILL LIKELY SPREAD INTO
SOUTHERN WISCONSIN LATER TONIGHT. KMSN SHOULD BE IN THE MVFR CIGS
THROUGH ABOUT 09Z...WITH MORE UNCERTAINTY ABOUT WHETHER THE CLOUDS
WILL MAKE IT ALL THE WAY TO THE LAKE SHORE. IF THEY DO...SIMILAR
TRENDS TO KMSN CAN BE EXPECTED AT KMKE/KUES/KENW.

&&

.PREV DISCUSSION... /ISSUED 330 PM CDT WED MAR 25 2015/

TONIGHT...FORECAST CONFIDENCE HIGH.

SHORTWAVE IMPULSE WILL CONTINUE TREKKING NORTHEAST AWAY FROM THE
AREA...AND INTO QUEBEC. BROAD CYCLONIC FLOW REMAINS IN PLACE
ALOFT...WITH LOW-LEVEL COLD ADVECTION. SURFACE LOW
PRESSURE...ATTENDANT TO THE LEADING SHORTWAVE...WILL MOVE INTO
QUEBEC WITH RESIDUAL TROUGHING EXTENDING SOUTHWESTWARD INTO NORTHERN
WISCONSIN. INITIALLY TIGHT PRESSURE GRADIENT WILL RELAX OVER THE
EVENING...ALLOWING GUSTY WESTERLY WINDS TO SUBSIDE A BIT BY 00Z.
925MB TEMPERATURES SUPPORT LOWS MOSTLY IN THE 20S...EXCEPT A FEW
LOWER 30S ALONG LAKE MICHIGAN.

THURSDAY...FORECAST CONFIDENCE HIGH

CYCLONIC FLOW CONTINUES ALOFT WITH A FEW WEAK IMPULSES RIPPLING
THROUGH THE MEAN TROUGH. A SURFACE COLD FRONT WILL DROP SOUTH ACROSS
THE AREA DURING THE AFTERNOOON HOURS. EXPECT CONTINUED COLD
ADVECTION...WITH TEMPERATURES SLOW TO WARM. AFTERNOON HIGHS WILL BE
IN THE UPPER 30S TO AROUND 40. AS THE FRONT MOVES THROUGH...A FLURRY
OR SPRINKLE IS POSSIBLE IN THE NE CWA...BUT MOISTURE APPEARS
LIMITED. PER COORDINATION WITH GRB...DROPPED SLIGHT CHANCE POPS FOR
THIS AREA DURING THE AFTERNOON HOURS.

SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY - FORECAST
CONFIDENCE...MEDIUM

BROAD 500 MB SHORTWAVE IMPULSE SWINGS THROUGH THE REGION LATE
THURSDAY INTO FRIDAY. GFS SHOWING SOME LIGHT QPF AMOUNTS JUST ALONG
THE LAKE MI SHORE LATE THURSDAY AND EARLY FRIDAY. HOWEVER...THE 12Z
NAM IS SHOWING NO QPF IN THE LATEST MODEL RUN...WITH THE ECMWF ALSO
GOING LIGHT ON ANY QPF AMOUNTS. DECIDED TO LEAVE SOME LIGHT POPS AND
QPF IN...BUT LIMITED THE AREAL COVERAGE FOR OUR EXTREME SOUTHEAST
COUNTIES. IF ANYTHING FALLS FROM THIS WAVE...SHOULD BE BRIEF
RAIN/SNOW MIX CHANGING TO ALL SNOW.

AS THIS WAVE MOVES OFF TO THE EAST...1002 MB HIGH PRESSURE SYSTEM
QUICKLY MOVES IN FOR LATE FRIDAY AND SATURDAY. ASSOCIATED SUBSIDENCE
AND A DRY AIR MASS WILL KEEP CONDITIONS QUIET THROUGH THE DAY
SATURDAY. THE HIGH WILL ALLOW NIGHT TIME TEMPERATURES TO DROP...WITH
LOWS FOR FRIDAY AND SATURDAY REACHING THE MID TO UPPER TEENS.

LONG TERM...SATURDAY NIGHT THROUGH SUNDAY - FORECAST
CONFIDENCE...MEDIUM

SATURDAY NIGHT WILL BE QUIET UNTIL A SFC LOW PRESSURE MOVES THROUGH
SOUTHERN CANADA AND THE NORTHERN GREAT LAKES. A COLD FRONT
ASSOCIATED WITH THIS LOW WILL BRING CHANCES OF PRECIPITATION TO
SOUTHERN WI DURING THE DAY SUNDAY. A 500 MB SHORTWAVE
IMPULSE...POSITIVE VORTICITY ADVECTION...AND DECENT ISENTROPIC OMEGA
OF 15-20 -UBAR/S ACCORDING TO THE GFS MODEL WILL PROVIDE MID LEVEL
SUPPORT. THE ECMWF AND GFS MODELS ARE ALSO SHOWING SOME DECENT 850
MB Q-VECTOR CONVERGENCE ASSOCIATED WITH THIS FRONTAL BOUNDARY.
PRECIPITATION TYPE LOOKS TO BE SNOW BETWEEN 06Z AND 12Z
SUNDAY...TRANSITIONING TO ALL RAIN BY THE LATE MORNING HOURS SUNDAY.
WINDS LOOK TO BE VERY STRONG THROUGH THE DAY SUNDAY INTO MONDAY WITH
A TIGHT SFC PRESSURE GRADIENT BEHIND THIS LOW...WITH GUSTS UP TO
35 KTS.

SUNDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM

FRONTAL BOUNDARY WILL BE THROUGH THE AREA BY SUNDAY NIGHT...AND
QUIETER CONDITIONS WILL RETURN FOR MONDAY AND TUESDAY AS HIGH
PRESSURE RETURNS TO THE REGION.

THE QUIET CONDITIONS WILL BE SHORT-LIVED HOWEVER AS ANOTHER
DISTURBANCE ARRIVES EARLY WEDNESDAY MORNING. THE GFS AND ECMWF
MODELS DIFFER ON THEIR SOLUTIONS...BUT BOTH SHOW SOME LIGHT QPF
AMOUNTS IN OUR FORECAST AREA. UNCERTAINTY EXISTS REGARDING THE
TIMING AND AMOUNTS OF PRECIPITATION AT THIS JUNCTION. SOUTHWEST
WINDS WILL HELP SUPPORT WARM AIR ADVECTION ACROSS THE AREA...WITH
HIGHS TUESDAY AND WEDNESDAY REACHING THE MID TO UPPER 50S...WITH
EVEN SOME 60S FOR OUR WESTERN COUNTIES.

AVIATION/00Z TAFS/...GUSTY WESTERLY WINDS WILL EASE AT THE TAF
SITES AFTER 00Z AS PRESSURE GRADIENT RELAXES. CIGS AND VSBYS HAVE
IMPROVED THIS AFTERNOON AND WILL BE IN THE VFR RANGE TONIGHT.
INITIALLY WESTERLY WINDS TONIGHT WILL VEER NORTHWESTERLY BY THURSDAY
AFTERNOON BEFORE TURNING NORTHERLY LATE THURSDAY EVENING.

MARINE...EXTENDED SMALL CRAFT ADVISORY UNTIL 10PM IN COORDINATION
WITH LOT. WESTERLY WINDS OF 15-20 KNOTS CONTINUE...WITH A RECENT
GUST TO 36 KT AT THE KENOSHA C-MAN STATION. WINDS WILL EASE
TONIGHT...WITH OFFSHORE FETCH LOWERING WAVES AS WELL.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ643>646.

&&

$$

UPDATE...DAVIS
TONIGHT/THURSDAY AND AVIATION/MARINE...SPM
THURSDAY NIGHT THROUGH WEDNESDAY...JTS


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