Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 192025
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
325 PM CDT SUN APR 19 2015

.TONIGHT AND MONDAY... FORECAST CONFIDENCE HIGH.

SURFACE LOW PRESSURE OVER SOUTHERN IL WILL TRACK NORTHWARD THROUGH
SOUTHERN LAKE MICHIGAN TONIGHT AND THROUGH LOWER AND UPPER MICHIGAN
ON MONDAY. THIS IS IN RESPONSE TO AN UPPER LEVEL SHORTWAVE EJECTING
OUT AHEAD OF A WEAKENING CUTOFF LOW OVER THE PLAINS. THE SURFACE LOW
TAPPED INTO GULF MOISTURE AND WILL BRING PRECIPITABLE WATER VALUES
UP TO 1.25 INCHES INTO SOUTHEAST WI THIS EVENING. STRONG OMEGA AND Q-
VECTOR CONVERGENCE DUE TO THE SHORTWAVE AND COUPLED UPPER JET WILL
LEAD TO A SOAKING RAIN OVER SOUTHEAST WI THIS EVENING.

THE QUESTION IS HOW FAR INTO SOUTH CENTRAL WI THAT SLUG OF PRECIP
WILL SPREAD. THERE WILL PROBABLY BE SHOWERS ACROSS THE REST OF
SOUTHERN WI AS THE SURFACE LOW TRACKS THROUGH SOUTHERN LAKE
MICHIGAN... BUT THEY SHOULD BE SPOTTIER WITH LOWER PRECIP AMOUNTS.

MEANWHILE... SHOWERS ASSOCIATED WITH A SURFACE TROUGH HANGING OUT
OVER EASTERN MN/WESTERN WI WILL GRADUALLY SHIFT EAST LATE TONIGHT
AND GET ABSORBED INTO THE DEFORMATION AREA ON THE BACK SIDE OF THAT
DEPARTING SURFACE LOW.

EXPECT SCATTERED TO NUMEROUS RAIN SHOWERS TO LINGER ACROSS MUCH OF
SOUTH CENTRAL AND SOUTHEAST WISCONSIN OVERNIGHT THROUGH MONDAY
MORNING. THE MODELS KEEP SLOWING DOWN THE SYSTEM... SO THEY NOW HAVE
PRECIP LINGERING THROUGH MUCH OF MONDAY AFTERNOON.

EXPECT BREEZY NORTHWEST WINDS ALL DAY MONDAY AS THE SURFACE LOW
TRACKS THROUGH MICHIGAN. CLOUDS AND SHOWERS WILL KEEP TEMPS DOWN
AROUND 50.


.SHORT TERM...MONDAY NIGHT THROUGH WEDNESDAY NIGHT

MONDAY NIGHT...FORECAST CONFIDENCE HIGH

UPPER LOW CONSOLIDATES AND DEEPENS IN THE VCNTY OF LAKE SUPERIOR BY
MONDAY EVENING...WITH THE SURFACE LOW IN SE ONTARIO. MAINLY CVA-
DRIVEN Q-VECTOR CONVERGENCE AND FRONTOGENETIC FORCING AT/ABOVE 700
MB LINGERS OVER THE AREA...SO WILL KEEP SLIGHT CHANCE POPS OVER THE
NORTHERN HALF OF THE CWA. 30 KT WEST WINDS WITHIN 1 K FT OVERNIGHT
...HOWEVER SHALLOW INVERSION DEVELOPING AROUND/AFTER 03Z SUFFICIENT
TO KEEP SURFACE DECOUPLED FROM THESE STRONGER WINDS...THOUGH A FEW
GUSTS TO 20 MPH NOT OUT OF THE QUESTION. MIXING AND CLOUDS HOLD LOWS
IN THE MID TO UPPER 30S.

TUESDAY AND TUESDAY NIGHT...FORECAST CONFIDENCE HIGH

INSTABILITY INCREASES WITH STEEP LOW-MID LEVEL LAPSE RATES AS COLD
POOL SETTLES OVER REGION. WILL BRING RAIN SHOWER CHANCES IN WITH
HIGHER MOISTURE AND OMEGA AS THEY INCREASE FROM NORTH TO SOUTH
DURING THE DAY...THEN SLIDE AWAY TO THE NORTHEAST TUESDAY EVENING.
925 MB TEMPERATURES AND THE CLOUDS AND SHOWERS SUPPORT HIGHS AROUND
50.

WEDNESDAY AND WEDNESDAY NIGHT...FORECAST CONFIDENCE HIGH

REGION STILL UNDER BROAD CYCLONIC FLOW WITH NEARLY-STACKED CLOSED
LOW SLOWLY FILLING JUST SOUTH OF JAMES BAY AND SURFACE RIDGING
NOSING INTO THE NRN PLAINS.  MODELS TAKE A BAND OF SHOWERS SOUTH
THRU CENTRAL IL WITH OMEGA AND MID-LEVEL MOISTURE WITH SHORT WAVE
WEDNESDAY...WHILE KEEPING MORE WIDESPREAD SHOWERS OVER NRN WI AND
LOWER MI...CLOSER TO THE SURFACE LOW. HIGHS AROUND 50 IN THE SW HALF
OF CWA WHILE NE HALF IN THE MID-UPPER 40S UNDER MORE CLOUD COVER.


.LONG TERM...THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM

CLOSED 500 MB LOW FILLS AND BROADENS AS VORTICITY MAXIMA "DUMBBELL"
AROUND THE 500 MB LOW CENTER AS IT SLOWLY TRACKS ENE FROM OVER/NEAR
THE EASTERN GREAT LAKES THURSDAY INTO THE NE U.S./ EASTERN CANADA BY
FRIDAY NIGHT. HOWEVER MODELS DIFFER WITH OVERALL CONFIGURATION OF
THIS PROCESS...WITH THE 12Z CANADIAN AND 12Z GFS DEPICTING A
BROAD...ELONGATED WEST TO EAST-ORIENTED CYCLONIC CIRCULATION OVER
THE ERN 1/2 OF CANADA...WITH THE GREAT LAKES UNDER THE SOUTHERN
PERIPHERY OF THIS BROAD FLOW INTO SATURDAY.

THE 12Z ECMWF KEEPS A TIGHTER CIRCULATION AROUND THE DEPARTING
CLOSED LOW...WITH RIDGING IN THE NORTHERN PLAINS THURSDAY MOVING
INTO THE WESTERN GREAT LAKES FRIDAY INTO SATURDAY.

WITH ALL MODELS SHOWING THE SOUTHERN LOBE OF A SURFACE HIGH CENTERED
OVER CENTRAL CANADA NOSING INTO WISCONSIN...HELPING TO KEEP THE
FOCUS OF BETTER PCPN CHANCES NO CLOSER THAN ACROSS NRN WI UNDER THE
SRN EDGE OF CYCLONIC FLOW ON THE GFS AND CANADIAN...WILL KEEP THE
THE EXTENDED DRY. TEMPERATURES WILL CONTINUE TO AVERAGE AT LEAST
FIVE DEGREES BELOW NORMAL THROUGH THE PERIOD.

&&

.AVIATION/00Z TAFS/...

RAIN EXPECTED ACROSS MUCH OF SOUTHERN WISCONSIN TONIGHT. INITIALLY
DRIER AIR WILL SLOW DOWN LOWER CIGS AND VSBYS UNTIL LATE EVENING.
THE HEAVIEST RAIN WILL OCCUR IN SOUTHEAST WI THIS EVENING. EXPECT
IFR CIGS WITH THE RAIN IN THE EVENING. THEN EXPECT FOG AND LIFR CIGS
TO DEVELOP AROUND MIDNIGHT AS THE RAIN TAPERS OFF THROUGH MONDAY
MORNING.

LOOK FOR GUSTY NORTHWEST WINDS WITH INCREASING CEILINGS AND
SCATTERED TO NUMEROUS RAIN SHOWERS ON MONDAY.

&&

.MARINE...

WINDS WILL BE FAIRLY LIGHT TONIGHT AS DEEPENING LOW PRESSURE TRACKS
FROM SOUTHERN IL TO SOUTHERN LAKE MICHIGAN OVERNIGHT. SFC DEWPOINTS
WILL LIKELY WARM INTO THE 40S OVERNIGHT.  WITH THE LAKE SFC TEMP IN
THE MID TO UPPER 30S... FOG MAY DEVELOP TONIGHT INTO MON MORNING.

LOOK FOR GUSTY NORTHWEST WINDS MONDAY AFTERNOON AND EVENING AS LOW
PRESSURE TRACKS ACROSS MICHIGAN. A SMALL CRAFT ADVISORY IS IN EFFECT.

WEST WINDS WILL LIKELY REACH SMALL CRAFT ADVISORY CRITERIA ONCE
AGAIN DURING THE DAY TUESDAY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM NOON TO 8 PM CDT MONDAY FOR LMZ643>646.

&&

$$

TONIGHT/MONDAY AND AVIATION/MARINE...MRC
MONDAY NIGHT THROUGH SUNDAY...REM


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