Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 112033
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
333 PM CDT FRI APR 11 2014

.SHORT TERM...

TONIGHT - CONFIDENCE...MEDIUM
SHORTWAVE WILL SHIFT EAST THIS EVENING AND TAKE BATCH OF
MID CLOUDS/SPRINKLES WITH IT. HIGH PRESSURE NUDGES INTO THE AREA
WITH LOW PRESSURE MOVING TOWARDS SW MN LATE. ONLY CIRRUS UPSTREAM.
DEW POINTS STILL VERY DRY SO EXPECT A GOOD DROPOFF WITH THE LIGHT
WINDS AND EVENTUAL CLEARING SKIES.

SATURDAY - CONFIDENCE...MEDIUM
COMPLEX FORECAST WITH NORTHWARD MOVING WARM FRONT IN THE MORNING
AND APPROACHING LOW FOR THE AFTERNOON. LIKE THE DEPICTION OF THE
4KM SPC WRF SHOWING A MORNING/ERLY AFTN ROUND OF SHRA/TSRA
ASSOCIATED WITH LIFT FROM EXIT REGION OF 850 JET CORE. DECENT 850
MOISTURE ADVECTION AS WELL. MODELS ALL BRING HIGHER DEW POINTS
FROM THE SRN PLAINS NORTHWARD INTO THE CWA...MORE AGGRESSIVE THAN
MOS. CIPS ANALOG IS GIVING A 40/50 PCT CHANCE OF DEWS GETTING ABV
55. IN FACT CIPS SHOWS A BETTER SHOT OF ACHIEVING THE FAVORABLE
DEWS THAN HITTING 70. CLEARING WILL DICTATE WHETHER WE HIT 70. MOS
IS COMING UP SHORT WITH OVC ALL DAY. NUDGED OUR FAR SOUTH TO NEAR
70...BUT IF BREAKS CAN BE GENERATED WE WILL GO ABOVE 70 IN MORE
LOCALES AS 850/925 SW WIND REGIME SETS UP AND WE WOULD MIX DOWN
AND WARM NICELY. CWASP NUMBERS IN THE 60-70 RANGE ACRS THE SRN CWA
DURG THE AFTN. 0-6 KM SHEAR WELL OVER 40 KNOTS...0-1 SHEAR 20-30
KNOTS. MID LEVEL LAPSE RATES 7.0-7.5C. THE POSITION OF THE UPPER
LEVEL JET WILL ALLOW FOR FAVORABLE UPPER DIVERGENT ACROSS SRN WI.
THIS SETUP HAS SOME THINGS GOING FOR IT SO UNDERSTANDABLE THAT SPC
EXTENDED THE DAY 2 OUT LOOK INTO SRN WI. CLEARING FROM MORNING 850
JET ACTIVITY AND DEGREE OF MOISTURE PUSH WILL DICTATE EVENTUAL
STORM SEVERITY. HAIL/WIND LOOKS LIKE THE PRIMARY THREAT AT THIS
TIME.

SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE...MEDIUM.

WE WILL HAVE A PROLONGED PERIOD OF WET WEATHER THIS WEEKEND INTO
EARLY NEXT WEEK. A SURFACE TROUGH WILL DROP SOUTHEAST THROUGH
SOUTHERN WI SATURDAY NIGHT WITH WINDS SHIFTING FROM SOUTH TO NORTH.
THIS TROUGH WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS MAINLY
IN THE EVENING...BUT WITH THE CHANCE CONTINUING ALL NIGHT IN THE
SOUTHERN FORECAST AREA. MODEL CONSENSUS SHOWS ABOUT A HALF TO THREE
QUARTERS OF AN INCH OF RAIN SATURDAY NIGHT.

THE SURFACE FRONT AND CORRESPONDING STRONG 925MB TEMPERATURE
GRADIENT MIGHT SNEAK BACK INTO SOUTHEAST WI SUNDAY MORNING. THERE
COULD BE A LULL IN PRECIP AT LEAST IN SOUTHEAST WI EARLY IN THE
MORNING. THEN THE NEXT SHORTWAVE COMING NORTHEASTWARD OUT OF THE
PLAINS WILL ARRIVE IN NORTHERN IL/SOUTHERN WI MIDDAY SUNDAY. THE NAM
IS FARTHEST NORTH WITH THE SURFACE LOW...WHICH ALLOWS THE WARM
SECTOR TO STALL OVER SOUTHEAST WI INTO EARLY AFTERNOON. THE OTHER
MODELS TRACK THE SURFACE LOW ACROSS NORTHERN IL AND THE WARM SECTOR
NEVER REACHES SOUTHERN WI. THIS MEANS UNCERTAINTY FOR TEMPERATURES
AND ALSO TOTAL PRECIPITATION AMOUNTS. THE FOCUS FOR PRECIP WILL BE
ON THE NORTH SIDE OF THIS SURFACE TROUGH/LOW PRESSURE DUE TO THE
LOCATION OF THE DEFORMATION ZONE...STRONGEST OMEGA AND BEST UPPER
DIVERGENCE WITH A COUPLED UPPER JET STRUCTURE. HALF TO ONE INCH OF
RAIN IS POSSIBLE DURING THIS TIME PERIOD...HIGHEST AMOUNTS OVER
CENTRAL AND SOUTHERN PORTIONS OF MKX FORECAST AREA.

THE SURFACE LOW AND COLD FRONT WILL SLIP SOUTHEAST OF WI SUNDAY
EVENING. THIS LOOKS LIKE THE PERIOD OF HIGHEST RAINFALL TOTALS FOR
SOUTHEAST WI WITH THE PASSAGE OF THE DEFORMATION ZONE. TEMPERATURES
ALOFT DROP BELOW FREEZING FROM NORTHWEST TO SOUTHEAST THROUGH THE
NIGHT. IT WILL BE A RACE BETWEEN THE FALLING TEMPERATURES ALOFT AND
AT THE SURFACE...AND HOW QUICKLY THAT DEFORMATION ZONE EXITS AND
ALLOWS THE DRIER AIR TO SETTLE IN THAT WILL DETERMINE HOW MUCH SNOW
WILL FALL. KEPT SIMILAR SNOWFALL AMOUNTS OF 1.5 TO 2 INCHES IN
PREVIOUS FORECAST. IT IS STILL UNCERTAIN HOW THE WARM GROUND WILL
HANDLE THE FALLING SNOW...BUT WHITE COVERED GROUND IN THE MORNING
SEEMS LIKELY FOR ALL BUT THE SOUTHEAST.

MODELS STILL DIFFER ABOUT HOW LONG THE SNOW/RAIN WILL PERSIST INTO
MONDAY. THE NAM AND ECMWF WAIT FOR THE MAIN UPPER TROUGH TO CLEAR WI
LATE MONDAY AFTERNOON BEFORE ENDING THE PRECIP. ANY LINGERING PRECIP
ON MONDAY WILL BE LIGHT THOUGH. MEANWHILE...GUSTY NORTH WINDS WITH
COLD AIR ADVECTION WILL LEAD TO A RAW DAY WITH HIGHS ONLY RISING
INTO THE UPPER 30S/LOWER 40S.

.LONG TERM...

MONDAY NIGHT THROUGH TUESDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

THE GFS IS SLOWER WITH BRINGING THAT UPPER TROUGH ALL THE WAY
THROUGH THE UPPER GREAT LAKES...AND THEREFORE GENERATES LIGHT SNOW
SHOWERS TUESDAY MIDDAY. NOT TOO CONFIDENT THERE WILL BE ENOUGH
MOISTURE AVAILABLE FOR ANYTHING BUT CLOUDS.

PERIODS OF CLEAR SKIES AND LIGHTER WINDS MON NIGHT AND TUE NIGHT
WILL LEAD TO LOWS IN THE 20S.

WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE LOW.

THE MODELS DIVERGE ENOUGH FOR THE MIDDLE OF NEXT WEEK TO HAVE A
COMPLETE DISAGREEMENT ABOUT THE PLACEMENT FOR WARM AIR ADVECTION
PRECIP AHEAD OF THE NEXT LOW PRESSURE SYSTEM ROLLING THROUGH THE
UPPER MIDWEST. THE ECMWF SUGGESTS SOUTHERN WI WOULD REMAIN DRY AND
THE GFS SPREADS RAIN AND SNOW INTO CENTRAL WI ON WEDNESDAY AND
WEDNESDAY NIGHT. PRECIP WOULD END AFTER THE COLD FRONT MOVES THROUGH
BEHIND THIS COMPACT SYSTEM BY FRIDAY MORNING.

COLDER AIR WILL SETTLE IN BRIEFLY FOR FRIDAY. THEN IT LOOKS LIKE A
FAIRLY ACTIVE WEATHER PATTERN NEXT WEEKEND WITH SMALL CHANCES FOR
RAIN.

&&

.AVIATION/00Z TAFS/...
MID DECK WITH ASSOC --RA/MOSTLY VIRGA SWINGING THROUGH SRN WI
THIS AFTN. BASES WILL REMAIN AT VFR LEVELS INTO THIS EVE WITH
MAINLY CIRRUS UPSTREAM IN SRN/CNTRL MN. RENEWED 850 MILLIBAR JET
CORE WILL DRIVE ADDITIONAL SHRA/TSRA DEVELOPMENT SAT MRNG. AFTN
DEVELOPMENT QUESTIONABLE WITH ENTRANCE REGION OF 850 JET CORE
BECOMING MORE PREDOMINANT. HOWEVER MODELS ALL SHOWING MORE STORM
DEVELOPMENT WITH SOME FAVORABLE FACTORS AT PLAY ESPECIALLY IF
SKIES CAN CLEAR OUT BRIEFLY AND HIGHER DEW POINTS ARRIVE FROM THE
CENTRAL PLAINS. LOW PRESSURE APPROACHES SRN WI DURG THE AFTN/EVE
SO FORCING WILL BE INCREASING WITH TIME.

&&

.MARINE...

WARM FRONT WILL TRY TO LIFT NORTHWARD THOUGH COLD LAKE TEMPS MAY
HAVE A SAY SO. DECIDED TO GO WITH THE SMALL CRAFT STARTING AT 15Z
TO COVER PREFRONTAL SE WINDS AND POST FRONTAL SSW WINDS. WILL
ALLOW FOR WINDS AND WAVES TO EASE A BIT IN THE EVENING SO KEPT THE
SMALL CRAFT GOING TO 3Z.

&&

.HYDROLOGY...

RIVERS ARE EXPECTED TO RISE OVER THE WEEKEND WITH THE PROLONGED
PERIOD OF RAIN COMING OUR WAY. INPUTTING THE FORECAST PRECIPITATION
AMOUNTS INTO VARIOUS RIVER GAUGE POINTS YIELDED ABOUT HALF A DOZEN
SITES THAT COULD RISE TO BANKFULL OR EVEN MINOR FLOODING. GIVEN THAT
THE RIVERS IN CONCERN ARE NOT IN A CONCENTRATED AREA...OPTED NOT TO
PUT OUT ANY AREAL HYDROLOGY FLOODING HEADLINES AT THIS TIME. WE WILL
CONTINUE TO KEEP AN EYE ON THE POTENTIAL FOR AREAL FLOODING.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM CDT SATURDAY FOR
     LMZ643>646.

&&

$$

TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR
SATURDAY NIGHT THROUGH FRIDAY...MRC



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