Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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674
FXUS63 KMKX 162037
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
337 PM CDT SAT MAY 16 2015

.SHORT TERM...

TONIGHT THROUGH SUNDAY AFTERNOON...FORECAST CONFIDENCE MEDIUM.

WIDELY SCATTERED THUNDERSTORMS PERSIST THROUGH LATE AFTERNOON. THESE
ARE BEING TRIGGERED BY A WEAK MID LEVEL SHORTWAVE APPROACHING FROM
IA/IL. MODEL SOUNDINGS AND RAP SPC MESOSCALE ANALYSIS ARE SHOWING
TALL SKINNY CAPE VALUES OF 1000 TO 2000 J/KG INLAND FROM THE
LAKESHORE THIS AFTERNOON. THERE IS NOT MUCH SHEAR... SO ONLY BRIEF
SMALL HAIL WOULD BE POSSIBLE IN ANY STRONGER STORMS. THE MAIN THREAT
WILL BE BRIEF HEAVY RAIN SINCE PRECIPITABLE WATER VALUES ARE AROUND
1.3 INCHES TODAY.

THESE THUNDERSTORMS WILL DIMINISH AFTER SUNSET THIS EVENING. LIGHT
WINDS AND SMALL DEWPOINT DEPRESSIONS WILL LEAD TO PATCHY FOG AND LOW
CLOUDS ACROSS SOUTHERN WI OVERNIGHT. THERE IS A CHANCE THAT MARINE
FOG WILL SPREAD INLAND ONCE AGAIN. THE CLOUDS WILL LIKELY LINGER
INTO THE MID SUNDAY MORNING HOURS.

SURFACE LOW PRESSURE OVER THE DAKOTAS WILL TRACK INTO MINNESOTA
TONIGHT AND STALL THROUGH SUNDAY AS IT OCCLUDES. THE 850 MB WARM
CONVEYOR BELT... OR WARM MOIST AIR TRANSPORT... WILL LIFT THROUGH
SOUTHERN WI SUNDAY MORNING INTO THE EARLY AFTERNOON. THIS WILL BRING
A BAND OF NUMEROUS SHOWERS AND THUNDERSTORMS THAT SHOULD MARCH
NORTHEAST ACROSS SOUTH CENTRAL AND SOUTHEAST WI. THERE IS SOME
CONCERN THAT AN EMBEDDED THUNDERSTORM COULD BECOME SEVERE DURING THE
AFTERNOON AS THE ATMOSPHERE BECOMES LESS STABLE. MODELS ARE HINTING
AT SOUTHEAST WI AND LAKE MICHIGAN HAVING THE GREATEST THREAT FOR
ENHANCED THUNDERSTORMS ON THE BACK EDGE OF THIS FIRST ROUND.

TEMPERATURES WILL RISE INTO THE UPPER 70S... SIMILAR TO TODAY.
LAKESHORE TEMPS WILL BE A LITTLE COOLER THAN INLAND GIVEN A SLIGHT
EASTERLY COMPONENT. WINDS WILL BE STRONG OUT OF THE SOUTH DUE TO A
TIGHT PRESSURE GRADIENT WITH THE APPROACHING SURFACE LOW.

LATE SUNDAY AFTERNOON THROUGH TUESDAY...FORECAST CONFIDENCE
MEDIUM.

THE OCCLUDED LOW OVER NW MN WILL WEAKEN TO A BROAD W-E SFC TROUGH
STARTING LATE SUNDAY NIGHT AND THROUGH MONDAY AS IT MOVES ACROSS
LAKE SUPERIOR AND INTO CANADA. BEFORE IT WEAKENS...THE PASSAGE OF
A TRAILING UPPER TROUGH AXIS AND A PREFRONTAL SFC TROUGH WILL
LIKELY INITIATE A NEW ROUND OF SCATTERED CONVECTION LATE SUNDAY
AFTERNOON AND THROUGH THE EVENING. THE NAM AND SOME MESOMODELS
ARE SHOWING WHAT WILL LIKELY BE DISCRETE SUPERCELLS DEVELOPING
FROM THE MS RIVER EWD. A 60-65 KT 500 MB JET STREAK WILL
ACCOMPANY THE UPPER WAVE...SUPPORTING 0-6 KM BULK SHEAR OF 50
KTS AND A SUPERCELL POTENTIAL WITH MLCAPE VALUES UP TO 1500 J/KG
OVER SOUTH CENTRAL WI. A TORNADO RISK WILL BE PRESENT DUE TO
0-1 KM SRH OF 150-200 M2/S2 AND 0-1 KM BULK SHEAR RISING TO 25
KTS. LCL HEIGHTS WILL ALSO BE AT OR BELOW 1 KM WITH THE LFC ONLY
SLIGHTLY HIGHER. SPC HAS UPGRADED TO AN ENHANCED RISK OF SEVERE
TSTORMS OVER MUCH OF WESTERN AND CENTRAL WI...MENTIONING THE
POSSIBILITY  OF STRONG TORNADOES. CAPE VALUES WILL REMAIN BELOW
1000 J/KG OVER ERN WI AND THE STORMS MAY NOT ARRIVE UNTIL THE
MIDDLE TO LATE EVENING...THUS THE SLIGHT RISK THERE. HOWEVER SHEAR
VALUES DO BECOME STRONG AS WELL.

THE ACTUAL COLD FRONT WILL GRADUAL MOVE ACROSS SRN WI ON
MONDAY...THUS 70 DEGREE HIGHS ARE EXPECTED. NWLY FLOW AND COLD
ADVECTION WILL THEN PREVAIL FOR MONDAY NIGHT AND TUESDAY. SRN WI
APPEARS TO BE FAR ENOUGH SOUTH TO AVOID THE BROKEN STRATUS ON
MONDAY BUT SOME STRATUS WILL BE POSSIBLE MONDAY NIGHT INTO
TUESDAY. A CANADIAN AIRMASS AND LINGERING CLOUDS INTO TUE
AFTERNOON WILL KEEP HIGH TEMPS ONLY IN THE 50S.


.LONG TERM...

TUESDAY NIGHT THROUGH SATURDAY...FORECAST CONFIDENCE MEDIUM.

A LARGE SFC HIGH WILL EXTEND FROM THE GREAT PLAINS TOWARD THE OHIO
RIVER VALLEY FOR THIS PERIOD. A RELATIVELY WEAK WNWLY FLOW ALOFT
WILL PREVAIL WITH BELOW NORMAL TEMPS EXPECTED IN THE BEGINNING OF
THE PERIOD BUT QUICKLY REBOUND TO SEASONAL NORMALS. NO PCPN IS
EXPECTED.


&&

.AVIATION/00Z TAFS/...COMING SOON.


&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...DENSE FOG ADVISORY UNTIL 10 AM CDT SUNDAY FOR LMZ643>646.

&&

$$

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



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