Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 230829
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
329 AM CDT WED APR 23 2014

.TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

250 MB NORTHWEST FLOW CONTINUES OVER SOUTHERN WISCONSIN THIS
MORNING BEFORE THE UPPER RIDGE REACHES THE MISSISSIPPI RIVER BY
EVENING. THE RIDGE WEAKENS AS IT ENTERS WISCONSIN TONIGHT. MAINLY
UPPER DIVERGENCE OCCURS TODAY AND TONIGHT...INCREASING OVER SOUTH
CENTRAL WISCONSIN TOWARDS SUNRISE THURSDAY.

WEAK 700 MB WARM AIR ADVECTION TODAY AND THIS EVENING...THEN
INCREASES LATE TONIGHT. 700 MB UPWARD MOTION IS WEAK BEFORE IT
INCREASES WEST OF MADISON TOWARD EVENING. 700 MB UPWARD MOTION
CONTINUES OVERNIGHT AS IT SPREADS EAST. NAM TAKES A 55 KNOT SPEED
MAX ACROSS SOUTHWEST IOWA TOWARD NOON...AND INTO THE IOWA/ILLINOIS
BORDER AREA TOWARDS EVENING...BEFORE WEAKENING IT AS IT CROSSES
NORTHERN ILLINOIS TONIGHT. THIS RESULTS IN FAIRLY STRONG 700 MB
MOISTURE CONVERGENCE MOVING ACROSS SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS EARLY THIS EVENING. THE MAIN 850 MB LOW LEVEL JET REMAINS
ACROSS IOWA AND MINNESOTA THIS EVENING...SLOWLY REACHING THE
MISSISSIPPI RIVER AREA LATE TONIGHT.

700 MB RH INCREASES OVER SOUTH CENTRAL WISCONSIN THIS
AFTERNOON...SATURATING WEST OF MADISON BY EVENING. SATURATION THEN
OCCURS ACROSS ALL OF THE FORECAST AREA TONIGHT.

THE SURFACE RIDGE AXIS WILL BE ACROSS FAR EASTERN WISCONSIN AT
SUNRISE...AND BE SLOW TO PUSH EAST...AND WILL STILL BE NEAR LAKE
MICHIGAN THIS AFTERNOON DUE TO THE COOL LAKES. MEANWHILE SOUTHEAST
WINDS WILL BEGIN TO INCREASE WEST OF MADISON LATE THIS
AFTERNOON...AND ACROSS ALL OF SOUTHERN WISCONSIN TONIGHT AS THE
TROUGH APPROACHES WISCONSIN.

EXPECT A DRY DAY TODAY...EXCEPT POSSIBLY WEST OF MADISON TOWARD
LATE AFTERNOON/EVENING...BEFORE RAIN OVERSPREADS THE AREA TONIGHT.
WEAK MID LEVEL CAPE OF ONLY 16 JOULES/KG LATE TONIGHT...SO WILL
NOT MENTION ANY THUNDER.

.SHORT TERM...THURSDAY THROUGH FRIDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.

HIGH POPS WILL CONTINUE FOR THURSDAY ACROSS THE AREA...AS STRONG
AND FOCUSED WARM AIR ADVECTION FED BY 850 MB LOW LEVEL JET SHIFTS
THROUGH THE AREA. NAM/GFS/CANADIAN MODELS TAKE SURFACE LOW
NORTHEAST ACROSS WISCONSIN ON THURSDAY INTO THURSDAY NIGHT...WITH
THE ECMWF KEEPING THE LOW TRACK DUE EAST ACROSS NORTHERN ILLINOIS.
COULD SEE THE ECMWF SOLUTION WORK OUT...AS THESE LOWS OFTEN TAKE
THAT TRACK WITH THE COOL ONSHORE FLOW REINFORCING THE COOL AIR
OVER THE AREA. THIS WOULD KEEP THE WARM SECTOR AIRMASS TO THE
SOUTH AS WELL.

FOR NOW...WENT WITH A CONSENSUS BLEND OF THE MODELS WITH THE LOW
TRACK. PRECIPITATION WILL LINGER IN THE EAST THURSDAY EVENING...AS
THE 500 MB SHORTWAVE TROUGH BECOMES NEGATIVELY TILTED AS IT MOVES
THROUGH THE AREA. PRECIPITATION SHOULD END LATER THURSDAY
NIGHT...WITH DRIER AIR WORKING INTO THE AREA. ONLY SLIGHT CHANCES
FOR THUNDERSTORMS...AS ELEVATED CAPES ARE VERY WEAK. USED
CONSENSUS BLEND FOR TEMPERATURES...GIVEN THE DIFFERENCES WITH THE
LOW TRACK AND WARM SECTOR PLACEMENT BETWEEN THE ECMWF AND
NAM/GFS/CANADIAN MODELS.

COLD FRONT DOES NOT PUSH SOUTHWARD THROUGH THE AREA UNTIL LATER ON
FRIDAY. THIS SHOULD COMBINE WITH GUSTY WEST TO NORTHWEST WINDS TO
BRING A MILD DAY TO THE AREA. AREA FORECAST SOUNDINGS SHOW SOME
WEAK MID LEVEL INSTABILITY WITH STEEP LOW TO MID LEVEL LAPSE
RATES. SOME MOISTURE IN THAT AREA TO WORK WITH...THOUGH MODELS
DISAGREE WITH 500 MB VORTICITY MAXIMUM PATH THROUGH THE REGION.
KEPT SMALL POPS FRIDAY AFTERNOON FOR SHOWERS.

COLD AIR ADVECTION FRIDAY NIGHT SHOULD BRING QUIET WEATHER BUT
COOL TEMPERATURES ACROSS THE AREA.

.LONG TERM...SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE IS
MEDIUM.

ECMWF AND GFS ARE MORE AGGRESSIVE WITH QPF WITH THE NEXT LOW
PRESSURE SYSTEM MOVING EASTWARD FROM THE CENTRAL PLAINS TO THE
MIDDLE MISSISSIPPI RIVER VALLEY REGION OVER THE WEEKEND AND INTO
EARLY NEXT WEEK. THEY KEEP THE AREA ON THE COOL SIDE OF THE
LOW...WITH SEVERAL ROUNDS OF QPF MOVING THROUGH THE AREA...MAINLY
SUNDAY NIGHT INTO TUESDAY. THERE ARE DIFFERENCES WITH THE 500 MB
LOW TRACK...THOUGH THEY DO SHOW A CUTOFF LOW MOVING SLOWLY
EASTWARD.

FOR NOW...USED CONSENSUS POPS AND TEMPERATURES FOR THIS PERIOD.
QPF AMOUNTS COULD BE IN THE 1 TO 2 INCH RANGE EASILY IF THIS
SCENARIO WORKS OUT...WHICH MAY AGGRAVATE AREA RIVERS ONCE AGAIN.

&&

.AVIATION/12Z TAFS/...

SURFACE HIGH PRESSURE WILL CONTINUE VFR CONDITIONS TODAY. EXPECT
AN INCREASE IN HIGH...THEN MID LEVEL CLOUDS THIS AFTERNOON AS A
TROUGH APPROACHES WISCONSIN TONIGHT.

IT WILL TAKE SOME TIME TO OVERCOME DRY AIR BELOW 700 MB...WITH
THE LATEST NAM KEEPING RAIN WEST OF KMSN THROUGH 00Z AND OUT OF
EASTERN TAF SITES THROUGH 06Z WED.

MAINLY VFR CIGS/VSBYS EARLY TONIGHT...WITH SOME MVFR CIGS/VSBYS
POSSIBLE IN RAIN LATE TONIGHT.

&&

.MARINE...

LIGHT EAST WINDS WITH HIGH PRESSURE ACROSS LAKE MICHIGAN TODAY.
SOUTHEAST WINDS WILL GRADUALLY INCREASE TONIGHT...BUT ARE EXPECTED
TO BE BELOW SMALL CRAFT ADVISORY CONDITIONS.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
THURSDAY THROUGH TUESDAY...WOOD



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