Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KMKX 232002
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
300 PM CDT THU APR 23 2015

.TONIGHT AND FRIDAY...FORECAST CONFIDENCE - HIGH.

HIGH PRESSURE WILL START OVERHEAD THIS EVENING...THEN SLOWLY MOVE
EASTWARD AHEAD OF APPROACHING LOW PRESSURE. THUS EXPECTING MOSTLY
CLEAR SKIES AND LIGHT WINDS MUCH OF THE NIGHT. WITH DEWPOINTS IN THE
20S OVERNIGHT...TEMPS SHOULD FALL INTO THE UPPER 20S AND LOW 30S
MOST PLACES. DID NOT GO AS QUITE AS COLD AS SOME OF THE COLDER
GUIDANCE DUE TO THE INCREASINGLY SHORTER NIGHTS...ALONG WITH A BIT
OF AN INCREASE IN WINDS AND CLOUDS FROM THE WEST LATER IN THE NIGHT
AS THE HIGH SHIFTS EASTWARD.

CLOUDS WILL CONTINUE TO INCREASE FRIDAY MORNING AND INTO THE
AFTERNOON UNDER MID LEVEL WARM ADVECTION. A LITTLE LIGHT RAIN MAY
SNEAK INTO THE WEST BY LATE AFTERNOON PER SOME OF THE
MODELS...THOUGH THE NAM KEEPS IT DRY THROUGH THE DAY DUE TO DRY AIR
IN THE LOWER LEVELS. HAVE SEEN THIS TYPE OF NAM SOLUTION PAN OUT
SEVERAL TIMES WITH THE FIRST ROUND OF PRECIP PUSHING INTO A DRY
EASTERLY FLOW. THUS KEPT POPS ON THE LOWER END THROUGH LATE
AFTERNOON...CONFINING THEM TO THE WEST.

GIVEN ENOUGH SUNSHINE THROUGH THE INCREASING CLOUDS...SHOULD SEE
HIGH TEMPS BACK TOWARD NORMAL VALUES MOST PLACES AS TEMPS INCREASE
ALOFT. IT WILL BE COOLER NEAR LAKE MICHIGAN THOUGH UNDER ONSHORE
WINDS.

.FRIDAY NIGHT AND SATURDAY...HIGH.

AMPLIFYING UPSTREAM TROFFING OVER WESTERN CONUS WL RESULT IN
SOUTHWEST SHORT WAVE TAKING A MORE NORTHEAST TRACK THROUGH THE
CENTRAL MS VALLEY REGION FRIDAY AND SATURDAY.  AHEAD OF THIS
WAVE...LOW LEVEL JET INCREASES TO 35 TO 45 KNOTS WILL BRING
INCREASING COLUMN PRECIPITABLE WATER INTO THE SRN WI REGION.  PWAT
VALUES ACROSS SRN WI INCREASE TO 0.75 TO 1.0 INCH WHICH IS ABOUT THE
75TH PERCENTILE FOR APRIL.  SHORT TERM GUIDANCE HAS BEEN TRENDING
SLIGHTLY NORTHWARD WITH THE MID-LEVEL CIRCULATION THAT PASSES BY TO
THE SOUTH OF WI ACROSS CENTRAL IL ON SAT.  TO THE NORTH OF THIS
CIRCULATION...BOTH NAM AND GFS SHOW STRONG LAYER Q-VECTOR
CONVERGENCE OF 10 TO 30 UNITS PASSING ACROSS SRN WI LATER FRI NGT
AND SAT.  300THETA SFC SHOWS 20 TO 30KT UPGLIDE WITH CONDENSATION
PRESSURE DEFICITS LESS THAN 5 MB FROM 06Z THRU 18Z SAT MRNG.  NEED
TO ACCOUNT FOR PERSISTENT ELY DRY FLOW ERODING SOME OF THE PRECIP AT
FIRST...ESPECIALLY IN THE EAST.  HENCE BUMPED UP POPS TO 60 PERCENT
OR HIGHER OVER WESTERN TWO THIRDS OF CWA LATER FRI NIGHT...AND
SLAMMED CATEGORICAL ACROSS MOST OF THE AREA SAT MRNG.  LOOKS LIKE A
RAW MORNING SAT WITH BLUSTERY EAST WINDS.  LINGERING DEFORMATION TO
THE NORTH OF THE SYSTEM WILL LIKELY CAUSE THE -RA TO CONTINUE INTO
THE AFTN.

CRITICAL THICKNESSES AND LOW LEVEL THERMAL PROFILE FAVOR MOSTLY
LIQUID SCENARIO FOR LATER FRI NGT INTO SAT.  SO PULLED THREAT OF -SN
FOR NOW.  NOT IMPOSSIBLE...SOME -SN MAY MIX IN WITH THE -RA LATER IN
THE MRNG AS THE LOW LEVELS COOL WHEN THE STRONGEST SYNOPTIC SCALE
FORCING MOVES THRU.

SATURDAY NIGHT AND SUNDAY...CONFIDENCE - MEDIUM.

THE SYNOPTIC SCALE FORCING SLIDES SOUTH OF THE AREA LATE SATURDAY
AND SATURDAY EVENING SO CONTINUED WITH DRY FORECAST SAT NGT FOR NOW.
POSSIBLE THAT SOME SMALL POP CHANCES MAY NEED TO BE ADDED TO SRN CWA
EARLY SAT EVENING AS -RA DIMINISHES OVER THE AREA...BUT TOO MUCH
UNCERTAINTY TO INCLUDE AT THIS POINT.  OTHERWISE...EXPECT GRADUAL
CLEARING.  SOME CU LIKELY TO REFORM ON SUNDAY AS THERMAL TROF
LINGERS OVER THE WESTERN GTLAKES.  EXPECT DAYTIME TEMPS TO BE 10 TO
15 DEGREES WARMER AWAY FROM LAKE MI ON SUN.

.SUNDAY NIGHT THROUGH THURSDAY...CONFIDENCE - HIGH TRENDING
TOWARD MEDIUM.

SLOW-MOVING UPPER LOW OVER NORTHEAST CONUS INTO WESTERN ATLANTIC WL
RESULT IN A PERIOD OF QUIET WEATHER PERSISTING INTO EARLY NEXT WEEK
AS SHORT-WAVE RIDGING SLIDES ACROSS WRN GTLAKES.  EXPECTED
INSOLATION WITH HIGH PRESSURE RIDGE WL RESULT IN TEMPS RETURNING TO
MORE SEASONAL LEVELS FOR THE LAST DAYS OF APRIL.  HOWEVER PERSISTENT
ONSHORE FLOW WL KEEP TEMPS CONSIDERABLY COOLER BY LAKE MICHIGAN INTO
TUE.  LAKE SURFACE TEMPS REMAIN IN THE 35 TO 40 RANGE.

ECMWF HAS BACKED OFF FROM STRONGER SHORT WAVE TROF IN NORTHWEST FLOW
AFFECTING PORTIONS OF WI ON TUE...WITH MORE POTENT PORTION OF WAVE
MORE IN LINE WITH GFS...REMAINING WELL NORTH IN SRN CANADA. HENCE
ABLE TO DROP LOW POPS FOR THE PERIOD TUE THRU WED.  SPLIT FLOW
REGIME KEEPS DEEPER MOISTURE AND HIGHER PRECIP THREAT OVER SRN CONUS
NEXT WEEK.

DISCREPANCY CREEPS IN AROUND MID-WEEK FROM MEDIUM RANGE
DETERMINISTIC GUIDANCE.  00Z ECMWF HAD BEEN TRANSITIONING TO MORE
ZONAL FLOW ACROSS NORTHERN CONUS WHILE GFS AND GEM THRU 144HR
CONTINUED MORE AMPLIFIED PATTERN.  ECMWF ENS MEAN ALSO TRENDING
TOWARD THIS SECOND SOLUTION AS HIGHLIGHTED BY NCEP WPC BLENDED
GUIDANCE. THEREFORE WL CONTINUE TEMP AROUND OR SLIGHTLY ABOVE
SEASONAL NORMAL AS THE MONTH FINISHES UP WITH SMALL CHANCES FOR
PRECIP RETURNING LATER NEXT WEEK.

&&

.AVIATION/00Z TAFS/...

VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE DAY FRIDAY. WILL
SEE INCREASING CLOUDS LATER TONIGHT AND INTO FRIDAY AHEAD OF
APPROACHING LOW PRESSURE. LATEST SOUNDINGS SUGGEST THAT THE DRY AIR
IN THE LOWER LEVELS WILL HOLD ON FOR QUITE A WHILE...LIKELY KEEPING
THE AREA MAINLY DRY THROUGH THE DAYTIME HOURS. A LITTLE LIGHT RAIN
MAY SNEAK INTO THE WEST BY EVENING PER SOME OF THE MODELS...THOUGH
THE NAM KEEPS IT DRY UNTIL AFTER MIDNIGHT. THE DRIER AIR SHOULD ALSO
KEEP CIGS GENERALLY AT OR ABOVE 5 KFT THROUGH LATE FRIDAY AFTERNOON.

&&

.MARINE...

A SMALL CRAFT ADVISORY MAY BE NEEDED SATURDAY...AS EAST TO NORTHEAST
WINDS INCREASE WHILE LOW PRESSURE PASSES BY TO THE SOUTH. THE WINDS
COULD GUST TO AROUND 25 KNOTS...BUILDING SOME HIGHER WAVES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...

WI...NONE.
LM...NONE.

$$
TONIGHT AND FRIDAY/AVIATION/MARINE...DDV
FRIDAY NIGHT THROUGH THURSDAY...MBK


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.