Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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813
FXUS63 KMKX 210230
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
930 PM CDT WED MAY 20 2015

.UPDATE...SHORT WAVE RIDGING IN THE LOWER LEVELS AND SYNOPTIC
SCALE FORCING SLIDING OFF TO THE EAST WILL ALLOW MID/HIGH CLOUDS
TO THIN THROUGH THE NIGHT. WITH TEMPERATURES STARTING OUT IN THE
COOL 40S...THINK THERE WILL BE ENOUGH TIME FOR READINGS TO GET A
FEW DEGREES COOLER BY LATE TONIGHT. LOWERED TEMPERATURES ACROSS
MOST OF THE AREA MORE INTO THE UPPER 30S TO AROUND 40. TEMPS NOT
EXPECTED TO BE COLD ENOUGH FOR FROST FORMATION.

&&

.AVIATION/06Z TAFS/...IF CLOUDS CLEAR QUICK ENOUGH...POTENTIAL FOR
LIGHT FOG TO DEVELOP LATE TONIGHT IN THE KENW AREA. HOWEVER FOR
NOW EXPECT MID/HIGH CLOUDS TO LAST MOST OF THE NIGHT IN THIS
AREA...WITH CLOUDS THINNING ELSEWHERE.

&&

.MARINE...STILL EXPECT RAPID CHANGE IN WIND DIRECTION OVER NEAR
SHORE WATERS THURSDAY EVENING AS BACKDOOR COLD FRONT ACCELERATES
SOUTHWARD ACROSS LAKE MICHIGAN. MAY BRIEFLY HAVE WIND GUSTS OF
20-25 KTS FOR AN HOUR OR TWO MARKING FRONTAL PASSAGE.


&&

.PREV DISCUSSION... /ISSUED 232 PM CDT WED MAY 20 2015/

SHORT TERM...

REST OF THIS AFTERNOON AND TONIGHT - CONFIDENCE...MEDIUM
MID/UPPER LEVEL SPEED MAX PER WATER VAPOR HELPING DEVELOP PRECIP
INTO SRN WI. MUCH OF THIS IN THE FORM OF VIRGA...BUT SOME GROUND
TRUTH IN THE FAR SOUTHERN AND WESTERN CWA. SPEED MAX PIVOTING IN ON
EASTERN SIDE OF ADVANCING MID LEVEL CIRCULATION BROADENING SHORTWAVE
SHIFTING EAST FROM SRN MN/NRN IA. EXPECT ANY LINGERING SPRINKLES/VRY
LGT RAIN TO WRAP UP BY LATER THIS AFTERNOON. MID LEVEL CLOUD DECK
EXTENDS WELL BACK INTO IA/SRN MN SO CLEARING LATER IN THE NIGHT.
THIS WILL KEEP TEMPS FROM DROPPING OFF AS MUCH AS THEY COULD WITH
THE DRY AIRMASS.

THURSDAY - CONFIDENCE...MEDIUM
WEST FLOW SETS UP AHEAD OF FRONT DROPPING SOUTH FROM NRN/CNTRL WI.
MILDER TEMPS WITH MORE SUN AND LOW LEVEL THERMAL RIDGE ACRS SRN WI.
925 TEMPS REACH 13-15C SO LOOKING FOR HIGHS AROUND 70. KEPT THE
SMALL POP IN FDL AND SBM CNTYS AS MODELS CONTINUE TO SHOW POTENTIAL
FOR SHRA SNEAKING IN THERE ASSOC WITH APPCHG FRONTAL BOUNDARY.

THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE IS HIGH.

THE UPPER LEVEL TROUGH EXTENDING INTO THE UPPER GREAT LAKES FROM
SOUTHEAST CANADA PUSHES INTO NEW ENGLAND FRIDAY. THE LEFT ENTRANCE
REGION OF THE 120 KNOT 250 MB JET IS ACROSS SOUTHERN WISCONSIN
THURSDAY NIGHT AND FRIDAY MORNING BEFORE PUSHING EAST. MAINLY WEAK
UPPER LEVEL CONVERGENCE ACROSS SOUTHERN WISCONSIN. FAIRLY DRY AT
700 MB. ALTHOUGH NOT SATURATED HIGHER 850 MB RH LINGERS.

THE SURFACE TROUGH AND WIND SHIFT WILL PUSH TO THE SOUTH THURSDAY
EVENING WITH A LARGE SURFACE HIGH CENTERED OVER THE WESTERN GREAT
LAKES FRIDAY. PRECIPITABLE WATER VALUES DRIES...BUT REMAINS AROUND
0.40 BY EARLY FRIDAY MORNING...SO RADIATION CONDITIONS ARE
SOMEWHAT MARGINAL. APPEARS ONLY PATCHY FROST POTENTIAL AT BEST IN
THE LOW AREAS.

FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM.

THE FLOW AT 250 MB IS NORTHWEST...AS A RIDGE BUILDS ACROSS THE
EASTERN PLAINS. FAIRLY NEUTRAL UPPER LEVEL DIVERGENCE. 700 MB RH
INCREASES SATURDAY BUT LITTLE UPWARD MOTION. A SLOW INCREASE IN
850 MB RH WHICH ALSO OCCURS INTO SATURDAY AFTERNOON BUT DOES NOT
SATURATE.

THE SURFACE HIGH GRADUALLY WEAKENS AND MOVES EAST WITH A LIGHT
SOUTH WIND DEVELOPING. EXPECT A LAKE BREEZE MAINLY NEAR LAKE
MICHIGAN. ONLY A HUNDRETH OF PRECIPITATION ON THE NAM LATE...WITH
THE 00Z ECMWF DRY...AND THE 12Z GFS HAVING A MORE EXPANDED AREA
OF LIGHT PRECIPITATION. PREFER THE DRIER MODELS.

LONG TERM...

SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE IS MEDIUM.

THE 00Z ECMWF KEEPS THE UPPER RIDGE ACROSS SOUTHERN WISCONSIN INTO
SUNDAY...WHILE THE RIDGE ON THE 12Z GFS IS WEAKER. AS A RESULT THE
GFS AND 06Z DGEX ARE WETTER...WITH THE 00Z ECMWF ONLY BRINGING IN
PRECIPITATION TO THE FAR SOUTH SUNDAY AFTERNOON.

MONDAY AND TUESDAY...FORECAST CONFIDENCE IS MEDIUM.

THE GFS TAKES THE SOUTHERN STREAM TROUGH NORTHEAST INTO SOUTHERN
WISCONSIN MONDAY NIGHT...WHILE THE 00Z ECMWF TAKES UNTIL TUESDAY.

BOTH THE GFS AND ECMWF HAVE RAIN ON MONDAY...WHILE THE FASTER GFS
ENDS IT TUESDAY AFTERNOON WITH THE ECMWF CONTINUING RAIN INTO
TUESDAY EVENING.

WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM.

A WEAK MID LEVEL TROUGH PUSHES INTO WISCONSIN WEDNESDAY. THE
SHORT WAVE IS A LITTLE STRONGER AND FASTER ON THE 12Z GFS.

THE 12Z GFS IS STRONGER WITH AN APPROACHING TROUGH AND BRINGS IN
SHOWERS TUESDAY NIGHT INTO WEDNESDAY...WHILE THE 00Z ECMWF BEGINS
THE SHOWERS WEDNESDAY.

AVIATION/00Z TAFS/...

SURFACE HIGH REMAINS IN CONTROL WITH FAIRLY
LIGHT WIND REGIME. MEANWHILE SHORTWAVE INDUCED CLOUD COVER IN PLACE.
PRECIP HITTING A WALL WITH LOW LEVEL DRY AIR IN PLACE. EXPECT VFR
CONDITIONS TO PERSIST FOR THE TAF SITES THOUGH SOME LOWERING OF
BASES EXPECTED ESPECIALLY SOUTH OF INTERSTATE-94...BUT STILL EXPECT
CIGS TO REMAIN AT VFR LEVELS. ANY RAIN EXPECTED IN THE SOUTHERN TIER
OF COUNTIES THROUGH LATE AFTN. EXPECT VFR CONDITIONS TO PERSIST INTO
THURSDAY WITH WESTERLY FLOW AHEAD OF FRONT DROPPING SOUTH INTO CNTRL
WI BY LATE AFTN THU. THIS FRONT AND ASSOCIATED WIND SHIFT NOT
EXPECTED INTO TAFS UNTIL AFTER 00Z FRIDAY.

&&

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

$$
UPDATE...MBK



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