Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 260930
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
330 AM CST THU FEB 26 2015

.TODAY...FORECAST CONFIDENCE IS MEDIUM.

PULLED TRIGGER ON LAKE EFFECT SNOW ADVY FOR THREE SOUTHEAST
COUNTIES EARLIER. OBSERVER IN OAK CREEK HAD REPORTED 4 INCHES OF
FLUFF BEFORE LAKE BAND HAD DEVELOPED. AROUND 07Z...IMPRESSIVE LAKE
EFFECT ENHANCED BAND RAPIDLY DEVELOPED OVER THE NEAR SHORE WATERS
AND SPREAD INLAND BY 0730Z. THIS WAS WHEN THE STRONGEST LOW LEVEL
CONVERGENCE AND PEAK LIFT WERE TO OCCUR OVER THE NEARSHORE
WATERS...SPREADING INLAND THRU PARTS OF THE THREE COUNTIES.

WITH BAND ORIENTATED NNE TO SSW AND MOVING TO THE SSW...HIGH SNOW
LIQUID RATIOS WOULD RESULT IN ADDITIONAL 1 TO 3 INCHES...ADDING TO
THE ALREADY 1 TO 3 INCHES THAT HAD ALREADY OCCURRED OVER MUCH OF
THE AREA.

LATEST RAP13 CONTINUES TO SHOW OMEGA LINGERING OVER SE MKE COUNTY
UNTIL ABOUT 14Z AND ERN RAC/KEN COUNTIES UNTIL 15Z OR SO. HOWEVER
DURING THIS TIME...LOW LEVEL FLOW BEGINS BACKING MORE TO THE NORTH
TO NORTHEAST...DECREASING FETCH AND LOW LEVEL RH ALSO DECREASES.
MAY NEED TO EXTEND LAKE EFFECT SNOW ADVY FOR AN HOUR OR TWO
PENDING STRENGTH OF LAKE BAND.

OTHERWISE...GRADUAL CLEARING SHOULD CONTINUE AS DRIER AIR SLIDES
ACROSS SRN WI TODAY. MAY BE SOME LINGERING SC FOR A TIME THIS AFTN
DUE TO LINGERING LOW LEVEL RH FLOW AND STEEP LOW LEVEL LAPSE
RATES.

.TONIGHT...FORECAST CONFIDENCE IS HIGH.

HIGH PRESSURE RIDGE AXIS REMAINS WEST OF WI OVERNIGHT TONIGHT AS
SHORT WAVE RIDGING SETTLES IN. INCREASING SUBSIDENCE SHOULD CLEAR
SKIES OVERNIGHT AS LOW LEVEL FLOW TURNS NORTHWEST. WITH LAKE
SUPERIOR PRETTY WELL ICE-COVERED...NOT THINKING MUCH THREAT OF
LAKE CLOUDS FROM THE NORTH.

ENOUGH MIXINESS OF 3 TO 5 KTS OVERNIGHT...AND OVERNIGHT LOWS FROM
4 TO 12 BELOW...TO RESULT IN A THREE HOUR WINDOW OF WIND CHILLS
AROUND 20 BELOW. WL LET DAY SHIFT MAKE FINAL DECISION ON WIND
CHILL ADVY.

.SHORT TERM...FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS
MEDIUM.

MODELS ARE IN GOOD AGREEMENT WITH TAKING ARCTIC HIGH PRESSURE FROM
WESTERN IOWA TO NORTHERN OHIO FRIDAY AND FRIDAY NIGHT. THE HIGH
WILL BRING QUIET WEATHER BUT CONTINUED COLD TEMPERATURES. GIVEN
MOSTLY CLEAR SKIES AND STRONG INVERSION JUST ABOVE THE
SURFACE...COULD SEE RADIATIONAL COOLING WITH LOWS EVEN COLDER THAN
CURRENTLY FORECAST FRIDAY NIGHT.

WIND CHILLS AGAIN HOVER AROUND 20 BELOW ZERO FOR A COUPLE
HOURS...THOUGH WINDS MAY BE TOO LIGHT IF DECOUPLING OCCURS. LATER
SHIFTS CAN EVALUATE NEED FOR WIND CHILL ADVISORY.

WARM AIR ADVECTION SLOWLY DEVELOPS ACROSS THE AREA SATURDAY INTO
SATURDAY NIGHT...AS THE HIGH MOVES FURTHER EAST OF THE REGION.
DEEP MOISTURE SHIFTS NORTHEASTWARD INTO THE AREA SATURDAY
NIGHT...ALONG WITH INITIAL 500 MB VORTICITY MAXIMUM. SURFACE COLD
FRONT THEN SHIFTS EASTWARD THROUGH THE REGION SUNDAY. TIMING OF
THE FRONTAL PASSAGE VARIES SOMEWHAT ON THE MODELS. UPWARD VERTICAL
MOTION SATURDAY NIGHT AND SUNDAY IS WEAK TO MODEST...THOUGH DOES
TAP DENDRITE SNOW GROWTH ZONE.

SREF PROBABILITIES OF MEASURABLE PRECIPITATION ARE OVER 90
PERCENT FOR SATURDAY NIGHT. THUS...RAISED POPS ESPECIALLY LATER
SATURDAY NIGHT...WITH LIKELY VALUES IN THE SOUTHWEST COUNTIES. MAY
NEED EVEN HIGHER POPS SATURDAY NIGHT INTO SUNDAY MORNING IN LATER
FORECASTS...IF MODELS REMAIN CONSISTENT. COULD SEE 1 TO 2 INCHES
OF SNOW ACCUMULATION NORTH...TO 2 TO 3 INCHES SOUTH...HIGHEST
AMOUNTS FAR SOUTHEAST.

.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE
IS MEDIUM.

MAIN ISSUE THIS PERIOD WILL BE SYSTEM FOR TUESDAY AND
PRECIPITATION AMOUNTS/TYPES. GFS/ECMWF ARE IN SOMEWHAT BETTER
AGREEMENT WITH THE SURFACE LOW TRACK. THEY TAKE LOW FROM CENTRAL
KANSAS TO CENTRAL ILLINOIS TUESDAY...THEN INTO THE EASTERN GREAT
LAKES REGION TUESDAY NIGHT. GOOD AMOUNT OF WARM AIR ADVECTION
OCCURS MONDAY NIGHT INTO TUESDAY...WITH STRONG MOISTURE ADVECTION
AND A 500 MB VORTICITY MAXIMUM PASSAGE INTO TUESDAY NIGHT.

MODELS SHOWING THE BEST UPWARD VERTICAL MOTION OVER THE AREA
TUESDAY. GFS FORECAST SOUNDINGS ARE SUGGESTING SOME MIXINESS OF
FREEZING RAIN/SLEET IN THE FAR SOUTH AND SOUTHEAST TUESDAY. RAISED
POPS FOR MONDAY NIGHT INTO TUESDAY NIGHT...HIGHEST ON TUESDAY.
SEVERAL INCHES OF SNOW ARE POSSIBLE...WITH SLEET/FREEZING RAIN
POSSIBLE...SO STAY TUNED.

&&

.AVIATION/12Z TAFS/...

HEAVIER SNOW SHOWERS WILL DIMINISH EARLY THIS MORNING AT KMKE AND
BY MID-MRNG AT KENW. EXPECT CIGS AND VSBYS TO RISE TO VFR SHORTLY
THEREAFTER. MAY BE SOME FEW-SCT SC LATER TODAY DUE TO LINGERING
LOW LEVEL RH AND STRONG LOW LEVEL LAPSE RATES.

&&

.MARINE...

GUSTY WINDS ASSOCD WITH SNOW SHOWERS OVER THE NEAR SHORE WATERS
SHOULD SETTLE DOWN EARLY THIS MORNING AS SNOW SHOWERS DIMINISH AND
PRESSURE GRADIENT GRADUALLY WEAKENS. DUE TO LIMITED TO NO TRAFFIC
AND BORDERLINE EVENT AFT 12Z...WL HOLD OFF ON ISSUING SMALL CRAFT
ADVY FOR SRN ZONES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
     WIZ066.

     LAKE EFFECT SNOW ADVISORY UNTIL 8 AM CST THIS MORNING FOR WIZ071-
     072.

LM...SMALL CRAFT ADVISORY UNTIL 10 AM CST THIS MORNING FOR LMZ645-646.

&&

$$

TODAY/TONIGHT AND AVIATION/MARINE...MBK
FRIDAY THROUGH WEDNESDAY...WOOD



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