Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 241630 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1130 AM CDT WED SEP 24 2014

.UPDATE...

500 MB SHORTWAVE TROUGH CONTINUES TO SLOWLY SHIFT EAST NORTHEAST
OVER MINNESOTA INTO WESTERN IOWA AND SOUTHWARD. DIFFERENTIAL
CYCLONIC VORTICITY ADVECTION WITH THIS FEATURE HAS GENERATED AN
AREA OF SHOWERS FROM WEST CENTRAL AND SOUTHWEST WISCONSIN INTO
CENTRAL IOWA AND SOUTHWARD.

HOWEVER...THERE IS A LOT OF DRY AIR IN THE LOWEST 5000 TO 10000
FEET OVER THE AREA AND EVEN TO THE WEST. NOT SEEING MUCH IN THE
WAY OF LIGHT RAIN/SPRINKLES AT THE SURFACE UNTIL THE AREA OF 35 TO
40 DBZ RADAR REFLECTIVITIES IN NORTHEAST INTO CENTRAL IOWA. HRRR
SEEMS TO HAVE A DECENT HANDLE ON THIS PRECIPITATION...SHIFTING
NORTHEAST AND POSSIBLY BRUSHING THE NORTHWEST AND FAR WESTERN
COUNTIES LATER THIS AFTERNOON INTO THE EVENING.

GIVEN THE AMOUNT OF DRY AIR IN THE LOW TO MID LEVELS...WILL LEAVE
THE FORECAST DRY FOR NOW. AT WORST...SOME SPRINKLES WOULD OCCUR IN
THE FAR NORTHWEST AND WESTERN COUNTIES.

MAINLY BROKEN MID TO HIGH CLOUDS SHOULD STICK AROUND THIS
AFTERNOON INTO THIS EVENING. HIGHS SHOULD STILL REACH THE LOWER
70S INLAND...TURNING COOLER LAKESIDE WITH ONSHORE WINDS
DEVELOPING.

&&

.AVIATION/18Z TAFS/...

VFR CONDITIONS ARE EXPECTED AT TAF SITES THIS AFTERNOON...TONIGHT
AND THURSDAY. MAINLY BROKEN MIDDLE TO HIGH CLOUDS WILL CONTINUE
TO MOVE THROUGH THE AREA THIS AFTERNOON AND TONIGHT. THEY MAY
LINGER INTO THURSDAY...BECOMING MORE SCATTERED IN AREAL COVERAGE.
ANY RAIN SHOWERS AND SPRINKLES SHOULD REMAIN WEST AND NORTHWEST
OF MADISON LATER THIS AFTERNOON INTO TONIGHT.

LIGHT SOUTHEAST WINDS ARE EXPECTED AT THE EASTERN SITES THIS
AFTERNOON...WITH LIGHT SOUTH TO SOUTHEAST WINDS AT MADISON. LIGHT
WINDS TONIGHT WILL AGAIN BECOME SOUTHEAST ON THURSDAY. MAY SEE
SOME GROUND FOG AGAIN LATER TONIGHT AT KENOSHA. HOWEVER...CLOUDS
SHOULD HOLD VISIBILITIES TO MVFR CATEGORY...IF IT OCCURS.

&&

.PREV DISCUSSION... /ISSUED 316 AM CDT WED SEP 24 2014/

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

A PORTION OF THE UPPER TROUGH APPROACHING FROM THE ERN GREAT PLAINS
WILL LIFT NEWD THROUGH THE UPPER MS RIVER VALLEY AND INTO CANADA.
THUS THE LOW LEVEL JET AND MOISTURE TRANSPORT WILL DECREASE OVER
THESE REGIONS LATER TODAY AND TONIGHT. DESPITE THIS...PWS WILL
INCREASE TO ONE INCH OVER THE WRN CWA FOR TNT WITH WEAK MID LEVEL
FRONTOGENESIS NOTED ON MODELS. FCST SOUNDINGS ALSO SHOW VERY
MARGINAL ELEVATED CAPE IN THE MID TO UPPER LEVELS OVER THE FAR WRN
CWA. THIS MATCHES UP WITH THE ERN EXTENT OF LIGHT MODEL QPF SO KEPT
SLIGHT CHANCES OF SHOWERS FOR THE FAR WRN CWA TONIGHT. SCT-BKN UPPER
LEVEL CLOUDS AND THE EARLIER DEVELOPMENT OF THE LAKE BREEZE WILL
KEEP TEMPS A FEW DEGREES COOLER THAN YESTERDAY. A SOMEWHAT MILD
NIGHT EXPECTED DUE TO INCREASED MID TO HIGH CLOUDS.

THURSDAY - CONFIDENCE...HIGH
MID LEVEL TROUGH AXIS BECOMES A WEAKLY CLOSED OFF CIRCULATION
ACROSS SRN WI. THIS FEATURE DROPS SOUTH OF THE STATE THURSDAY
NIGHT. THE LOW LEVELS REMAIN ANTICYCLONIC AND QUITE DRY LOOKING
PER BUFKIT SOUNDINGS. IN FACT CONSENSUS OF GFS AND NAM SOUNDINGS
IS FOR SOME MID CLOUDINESS AT BEST. 925 TEMPS ARE 14-16C SO
LOW/MID 70S FOR MOST.

FRIDAY THROUGH SUNDAY - CONFIDENCE...HIGH
MODELS VARY ON HANDLING OF UPPER LOW ACROSS THE PLAINS AND UPPER
MIDWEST. HOWEVER IN THE LOW LEVELS THE AIRMASS WILL REMAIN DRY AND
STABLE SO WILL KEEP FORECAST DRY. SURFACE HIGH WILL CONTINUE TO
RIDGE INTO SRN WI FROM THE EAST. JUST A SUBTLE INCREASE IN 925
TEMPS THIS PERIOD. EXPECTING HIGHS IN THE 70S THIS PERIOD AND
POTENTIALLY A BIT DEEPER INTO THE 70S BY SUNDAY WITH 925 TEMPS
18-19C BY THEN.

SUNDAY NIGHT THROUGH MONDAY NIGHT - CONFIDENCE...LOW
MAIN ISSUE WILL BE TIMING OF A BACK DOOR COLD FRONT SLIDING IN
FROM THE NORTH. THE ECMWF SLIDES IT SOUTH FAIRLY QUICKLY ON SUNDAY
NIGHT WHILE THE GFS SHOWS THIS FEATURE ARRIVING LATER MONDAY OR
MONDAY NIGHT. THE SUPERBLEND WINDS TEND TO FAVOR THE EARLIER
ARRIVAL PLAYED OUT BY THE ECMWF. MOST LIKELY THIS WILL BE A DRY
FRONT. GFS APPEARS TO BE OVERDOING THE PRECIP. AGAIN PREFER THE
DRY LOOK OF THE ECMWF.

TUESDAY - CONFIDENCE...LOW
PREFER THE CONSENSUS OF THE TRENDS IN GEM/ECMWF WITH UPPER LOW
SLOWLY EJECTING FROM MID MISSISSIPPI VALLEY. AT THIS TIME TRACK
AND TIMING OF THE LOW SUGGESTS MORE OF A GLANCING SHOT OF PRECIP
SHIELD IN ERN WI. MEANWHILE GFS SHOWS UPPER SYSTEM FURTHER WEST
WITH INFLUENCE OF SURFACE KEEPING ALL PRECIP AT BAY.

AVIATION/12Z TAFS/...VFR CONDITIONS TODAY THROUGH THURSDAY.
SCT-BKN150-200 CIRRUS CLOUDS.

&&

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

$$

UPDATE...WOOD
TODAY/TONIGHT AND AVIATION/MARINE...COLLAR
THURSDAY THROUGH TUESDAY...GEHRING


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