000
FXUS63 KMKX 182042
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
342 PM CDT SAT MAY 18 2013

.VERY SHORT TERM...TONIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM.

SHOWERS AND ISOLATED THUNDERSTORMS ARE NOT DEVELOPING DUE TO THE
VERY SHALLOW LAYER OF CU OVER THE REGION...THUS REMOVED MENTION FROM
AFTERNOON FORECAST. THERE COULD STILL BE A FEW SPRINKLES...BUT THAT
WOULD BE ALL.

QUIET WEATHER IS EXPECTED TONIGHT WITH SCATTERED HIGH CLOUDS OVER
SOUTHERN WI. THE LOW LEVEL MOISTURE THAT MADE IT INTO SOUTHERN WI
THIS AFTERNOON AND LIGHT SURFACE WINDS TONIGHT WILL LEAD TO PATCHY
FOG DEVELOPING AFTER MIDNIGHT. OVERNIGHT CONVECTION OVER IA/MN IS
EXPECTED TO STAY WEST OF THE MKX FORECAST AREA UNTIL SUNDAY MORNING.
LOW LEVEL MOISTURE MADE IT INTO SOUTHERN WI THIS AFTERNOON...AND
WITH THE LIGHT SURFACE WINDS...PATCHY FOG SHOULD DEVELOP AFTER
MIDNIGHT.

BY SUNDAY MORNING...ANY OVERNIGHT CONVECTION WILL BE QUICKLY
DISSIPATING AS IT TRACKS INTO WESTERN/CENTRAL WI. LINGERING
SHOWERS/ISOLATED THUNDER COULD BRUSH PORTIONS OF SOUTH CENTRAL WI
SOMETIME SUN MORNING...SO KEPT SLIGHT CHANCE MENTION THERE.

IT WILL BE A WARM AND HUMID DAY ON SUNDAY. DEW POINTS WILL BE IN THE
LOWER 60S OVER MUCH OF THE AREA...WITH THE EXCEPTION OF RIGHT ALONG
THE LAKESHORE DUE TO SOUTHEAST TO EAST WINDS. 925MB TEMPS INCREASE
TO 20 TO 21C...YIELDING MAX TEMPS IN THE LOWER 80S INLAND. THERE
SHOULD BE SHALLOW CU OVER THE AREA...AND INCREASING SOUTH WINDS.

A 500 MB SHORT WAVE AND LINE OF 850 MB FRONTOGENESIS WILL TRACK
NORTHEAST ACROSS CENTRAL WI SUN AFTERNOON. THE EXACT PLACEMENT AND
TIMING OF THESE FEATURES WILL DETERMINE WHERE THE CONVECTION SETS
UP. MOST MODELS ARE SHOWING THIS DEVELOPING IN IOWA AND THEN
TRACKING INTO SOUTHERN WI SUNDAY EVENING. A FEW MESOSCALE MODELS ARE
SHOWING ISOLATED CONVECTION DEVELOPING OVER SOUTH CENTRAL WI ALREADY
SUN AFTERNOON...AND THEN ANOTHER BIGGER AREA OF CONVECTION WOULD
MOVE ACROSS IN THE EVENING. IF AFTERNOON CONVECTION WOULD
DEVELOP...SURFACE-BASED CAPE OF 1000-1500 J/KG AND 0-6KM SHEAR
AROUND 20 KNOTS WOULD SUPPORT MARGINALLY SEVERE HAIL. SOUTHEAST WI
HAS THE LEAST CHANCE FOR PRECIP DURING THE DAY SUNDAY.

.SHORT TERM...SUNDAY NIGHT THROUGH TUESDAY. FORECAST CONFIDENCE MEDIUM.

SEVERAL ROUNDS OF SEVERE WEATHER POSSIBLE DURING THIS PERIOD.

CONVECTION EXPECTED TO BE ONGOING OVER THE FAR WEST AT THE START OF
THE PERIOD. LOW-LEVEL JET INCREASES SUNDAY NIGHT AHEAD OF DEEPENING
LOW...BUT SOME MODEL PLACEMENT/TIMING DIFFERENCES OF SYSTEM AND
RESULTING LOCATION OF JET AXIS THAT AFFECTS BEST MOISTURE TRANSPORT
AND FORCING. ALL MODELS SHOW A COMPLEX DEVELOPING TO THE WEST SUNDAY
EVENING AND MOVING WITH JET AS IT HEALS OVER TO THE EAST AND
WEAKENS. QUESTION IS WHETHER IT MOVES DUE EAST AS THE GFS AND ECMWF
SUGGEST...OR LIFTS MORE NORTH THAN EAST AS SEEN ON GEM/NAM.

LAYER Q-VECTOR CONVERGENCE MAXES REFLECT INCREASING DYNAMIC LIFT AS
ALL MODELS SHOW NEGATIVE-TILT SHORT WAVE TROUGH LIFTING THROUGH
REGION SUNDAY NIGHT/MONDAY AROUND MID-UPPER LEVEL LOW AS IT CLOSES
OFF OVER THE S DAKOTA/NEBRASKA BORDER REGION...BUT AGAIN EXACT
TIMING TRACK WILL HAVE A BIG SAY IN WHERE STRONGEST STORMS FORM ON
MONDAY.

THE CWASP PROBABILITY IS INDICATING AT LEAST THE WESTERN CWA HAS A
POTENTIAL FOR SEVERE SUNDAY NIGHT...AND A BETTER PROBABILITY FOR THE
ENTIRE CWA ON MONDAY...SUPPORTING SPC HAS DAY 2 SLIGHT RISK INTO THE
WEST AND THE ENTIRE FORECAST AREA IN THE DAY 3 SLIGHT RISK.

ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...WITH SEVERE
POSSIBLE...TUESDAY INTO TUESDAY NIGHT AS YET ANOTHER SHORT WAVE
TROUGH ROTATING AROUND MAIN CIRCULATION CENTER LIFTS THROUGH THE
REGION...WITH THE CWA REMAINING IN OR NEAR THE WARM SECTOR. THE GFS
AND GEM...AND TO SOME DEGREE THE ECMWF...STILL MAINTAIN HIGH VALUES
ON THE CWASP OVER THE CWA FOR TUESDAY.

PRECIPITABLE WATER VALUES ARE 120 TO 160 PCT OF NORMAL DURING THIS
TIME...AND WITH REPEATED ROUNDS OF SHOWERS AND
THUNDERSTORMS...BRINGS THE RISK OF AREAL FLOODING. RAINS YESTERDAY
SLOWED THE FALLING TREND TO AREA RIVERS AND PRODUCED STANDING WATER
IN SOME FIELDS...INDICATING SUSCEPTIBILITY OF REGION TO A PROLONGED
PERIOD OF RAIN. MODEL TOTAL QPF VALUES FROM SUNDAY AFTERNOON THROUGH
FRIDAY VARY BY AS MUCH AS 1.5 INCHES...GENERALLY RANGING FROM 1.5 TO
3 INCHES TOTAL. IT MUST BE REMEMBERED THAT IT IS AN AREAL AVERAGE...
WITH CONVECTION PRODUCING LOCALLY HIGHER AMOUNTS. GIVEN THE
UNCERTAINTY AMONG THE MODELS FOR QPF AMOUNTS AND PLACEMENT...WILL
ISSUE AN ESF FOR FLOODING POTENTIAL FOR THE ENTIRE CWA. WILL HAVE TO
WATCH RIVERS THAT HAVE JUST RECENTLY GONE BACK WITHIN THEIR BANKS TO
RISE BACK UP WITH THE PROLONGED PRECIPITATION PERIOD AHEAD.


.LONG TERM...WEDNESDAY THROUGH SATURDAY. FORECAST CONFIDENCE MEDIUM.

MODELS FINALLY BEGIN TO FILL/ACCELERATE THE SYSTEM EAST WEDNESDAY
AND THURSDAY. THE CWA WILL STILL BE IN THE WARM SECTOR AHEAD OF THE
SURFACE LOW/TROUGH WITH ENOUGH INSTABILITY FOR THUNDERSTORMS INTO
WEDNESDAY...ESPECIALLY THE SOUTHEAST. PRECIPITATION CHANCES LOWER
AND MODE CHANGES OVER TO RAIN SHOWERS WEDNESDAY NIGHT LINGERING
INTO THURSDAY UNTIL MID-LEVEL TROUGH CLEARS REGION. SHORT WAVE
RIDGING AND COOL SURFACE HIGH PRESSURE BRING DRY WEATHER FOR THE
START OF THE MEMORIAL DAY HOLIDAY...THOUGH HIGHS FRIDAY AND SATURDAY
WILL BE 5 TO 8 DEGREES BELOW NORMAL.

&&

.AVIATION/00Z TAFS/...

REMOVED AFTERNOON MENTION OF SHOWERS IN FORECAST GIVEN THE SHALLOW
CUMULUS CLOUDS. OTHERWISE...JUST SOME HIGH CLOUDS OVER THE REGION
THROUGH MIDNIGHT.

FOG IS MORE LIKELY TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING BUT
TOO MUCH UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN MVFR
VSBYS AT THIS POINT.

PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED FROM SUNDAY
AFTERNOON THROUGH WEDNESDAY AS SLOW MOVING LOW PRESSURE MOVES ACROSS
THE AREA. INCREASING HUMIDITY WILL LEAD TO THE POSSIBILITY FOR
STRONG TO SEVERE THUNDERSTORMS SUNDAY NIGHT AND MONDAY.

&&

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

$$

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