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000
FXUS63 KMKX 212039
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
339 PM CDT TUE MAY 21 2013

.VERY SHORT TERM...TONIGHT AND WEDNESDAY.

TONIGHT - CONFIDENCE...MEDIUM
TWO DISTINCT CIRCULATION CENTERS SHOW UP NICELY ON WATER VAPOR. THIS
FIRST IN NORTHERN MN AND THE SECOND ON THE SD/MN BORDER. ISOLD TSRA
POPPED UP ALONG WIND SHIFT/MOISTURE GRADIENT DURING THE AFTERNOON.
UPPER JET CORE ON EASTERN SIDE OF CIRCULATION CENTER CONTINUES TO
STREAM ACROSS THE UPPER MIDWEST. IN THE LOW LEVELS DRY AIR HAS
WRAPPED IN ON SW WINDS. A SECONDARY LOW IS EXPECTED TO DEVELOP
ACROSS SOUTHERN IL AND THEN TRACK UP NEAR CHICAGO BY 12Z.
MOISTURE/QPF SNEAKS INTO THE FAR SE BETWEEN 6-12Z...THE GFS BEING A
COMPROMISE BETWEEN THE DRY NAM AND THE MORE ROBUST 12Z ECMWF.

WEDNESDAY - CONFIDENCE...MEDIUM
PASSING LOW TO OUR SOUTH AND EAST IN COMBO WITH EVOLVING SURFACE
TROUGH/850 TROUGH SETS UP DECENT LOWER LEVEL MOISTURE FLUX
CONVERGENCE WITH THE CONVERGING LOW LEVEL WIND FIELDS. THIS COMBINED
WITH THE GRADUAL PROGRESSION OF THE UPPER LOW TOWARDS WI SHOULD
RESULT IN A DECENT COVERAGE OF SHRA. CAPE IS LIMITED SO NOT THINKING
HIGHLY OF THUNDER POTENTIAL.

.SHORT TERM...WEDNESDAY NIGHT THROUGH FRIDAY.

STACKED LOW...NOW EVOLVING INTO AN OPEN TROUGH...MOVES ACROSS AND
OUT OF FORECAST AREA AS IT PHASES WITH SHORT WAVE TROUGH DROPPING
ACROSS HUDSON BAY/JAMES BAY PRODUCING A LONG WAVE TROUGH OVER THE
EASTERN U.S. THAT EVENTUALLY CLOSES OFF OVER THE CANADIAN MARITIMES
SATURDAY. SURFACE HIGH PRESSURE BUILDS IN OVER THE AREA BEHIND THE
DEPARTING LOW WITH NORTHERLY WINDS AND COOLER TEMPERATURES.

WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE MEDIUM.

WILL KEEP LIKELY POPS IN THE EVENING AS DEFORMATION ZONE ASSOCIATED
WITH 850-700 MB LOWS DROPS THROUGH REGION REFLECTED IN LAYER
Q-VECTOR CONVERGENCE MAXIMA...SLOWLY DIMINISHING FROM NW TO SE AFTER
06Z. WILL KEEP A CHANCE THURSDAY MORNING FOR THE SE 1/2 UNTIL CVA
WITH LAST TRAILING SHORT WAVE CLEARS THE EAST AROUND 18Z.

FORECAST QPF THROUGH 00Z FRIDAY IS FOR A FAIRLY WIDESPREAD 0.50 TO
0.75 INCH RAINFALL FOR THE CWA...BUT IF ATMOSPHERE BECOMES A BIT
MORE UNSTABLE THAN EXPECTED WITH A FEW THUNDERSTORMS...AMOUNTS COULD
GO LOCALLY HIGHER THOUGH THUNDER CHANCES REMAIN TOO LOW TO MENTION
AT THIS TIME.

FORECAST SOUNDINGS AND 925 MB TEMPS INDICATE LOWS WILL BE IN THE
UPPER 40S TO LOWER 50S WEDNESDAY NIGHT...WITH THURSDAY HIGHS ONLY IN
THE MID-UPPER 50S WITH FLOW OFF OF THE LAKE IN THE EAST...WHILE
SUPERADIABATIC BUMP ALLOWS MID 60S IN THE WEST.

THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.

COLD AIR SETTLES OVER REGION UNDER THE CORE OF THE SURFACE
HIGH...WITH 925 MB TEMPERATURES OF 4C TO 5C BY 12Z FRIDAY. WITH
DECOUPLED WINDS AND CLEAR SKIES LOW TEMPERATURES WILL FALL INTO THE
UPPER 30S EXCEPT IN THE HIGHER ELEVATIONS OF WESTERN SOUTH CENTRAL
WISCONSIN AND ALONG THE LAKE. SOME LOWER LOCATIONS LIKE THE VALLEYS
OF THE KETTLE MORAINE MAY SEE FROST.

HIGH SHIFT EAST THURSDAY...ALLOWING A LIGHT SOUTHEAST TO SOUTH FLOW
OVER THE WESTERN HALF OF THE CWA...WITH 925 MB TEMPERATURES
RECOVERING TO 10C TO 12C. EXPECT MID TO UPPER 60S THERE...WHILE
SINGLE DIGIT 925 MB READINGS AND AFTERNOON LAKE BREEZE HOLD HIGHS IN
THE MID 50S TO AROUND 60 IN THE EAST.

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. FORECAST CONFIDENCE
MEDIUM TO LOW.

EVENTUAL LOCATION OF CLOSED LOW AND UPPER JET KEY TO
WEATHER...ESPECIALLY FOR THE HOLIDAY WEEKEND. GFS HAS A WEAKER
NARROWER 850 MB RIDGE OVER THE REGION WHICH ALLOWS PERIODS OF
SHOWERS...AND POSSIBLE THUNDERSTORMS...TO FIRE ALONG BAROCLINIC
RIBBON THAT BECOMES SITUATED ALONG THE MS RIVER. SUBSEQUENT
ISENTROPIC LIFT/SLOPED FRONTOGENETIC FORCING ALONG THE TEMPERATURE
GRADIENT ENHANCED BY UPPER LEVEL DIVERGENCE OF RIGHT ENTRANCE OF
PERSISTENT 250 MB JET MAX. ECMWF FARTHER WEST WITH BAROCLINIC ZONE
AND KEEPS PCPN WEST OF CWA AFTER GLANCING THE REGION FRIDAY NIGHT.
BLENDED POPS KEEPS CHANCE POPS IN THE WEST FROM FRIDAY NIGHT THROUGH
SATURDAY NIGHT...AND SLIGHT CHANCE IN THE EAST. MODELS DIVERGE FOR
THE LATTER HALF OF THE WEEKEND...WITH ONLY SLIGHT CHANCE POPS DUE TO
BLENDING. AFTER ONLY REACHING THE 60S FOR HIGHS FRIDAY THROUGH
SUNDAY...70S TRY TO PUSH BACK IN FOR MONDAY...BUT MAINLY IN THE SW
PORTION OF CWA.

&&

.AVIATION/00Z TAFS/...LOW LEVEL DRY AIR INFLUX FROM THE SOUTHWEST
HAS DIMINISHED INSTABILITY. PLENTY OF CLOUD COVER WRAPPING AROUND
MID/UPPER CIRCULATION CENTERS IN THE PLAINS. A LOT OF THIS HAS A
DIURNAL LOOK TO IT. EXPECT MORE CLOUD COVER LATER TONIGHT INTO
WEDNESDAY AS SECONDARY SURFACE LOW HEADS NORTHEAST. MODELS BRING
MORE PRECIP INTO THE AREA WITH THIS FEATURE AND EASTWARD PUSH OF
SLOW MOVING MID LEVEL CIRCULATION FROM THE PLAINS. SO EXPECTING MVFR
CEILINGS WITH A GOOD DEAL OF SHRA.

&&

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

$$

TONIGHT/WEDNESDAY AND AVIATION/MARINE...COLLAR
WEDNESDAY NIGHT THROUGH TUESDAY...REM