Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 211627 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1127 AM CDT THU AUG 21 2014

.UPDATE...

THE HRRR... 00Z WRF-ARW AND NMM... 00Z SPC WRF AND 00Z SPC STORM
SCALE ENSEMBLE OF OPPORTUNITY HAVE A PRETTY GOOD HANDLE ON THE
MORNING CONVECTION ACROSS SOUTHERN WI. THESE MODELS ALL WEAKEN THE
STORMS AS THEY TRACK EAST THROUGH EARLY AFTERNOON...WHICH RADAR
TRENDS ARE CURRENTLY SHOWING.

A FEW SHOW SOME STORMS RE-DEVELOPING OVER SOUTHWEST WI EARLY THIS
EVENING THAT COULD TRACK EAST ACROSS THE NORTHERN MKX FORECAST AREA.
THE OTHERS INCLUDING THE 12Z NAM AND GFS SHOW NOTHING HAPPENING AT
ALL THIS EVENING AND PRETTY MUCH THROUGH THE OVERNIGHT. THE 12Z NAM
SEEMS TO BE TOO SLOW WITH ITS QPF SOLUTION BASED ON WHAT ALREADY
HAPPENED THIS MORNING...SO IF I MENTALLY CHANGE THE TIME TO BE VALID
6 HOURS EARLIER...THE NAM ACTUALLY SEEMS REPRESENTATIVE OF WHAT
COULD HAPPEN THROUGH TONIGHT.

THE 12Z MESO MODELS WILL BE COMING IN AROUND 17Z SO I WILL TAKE
ANOTHER LOOK AT THOSE SOLUTIONS. BUT I AM THINKING I WILL BE
SIGNIFICANTLY TAKING DOWN POPS ACROSS SOUTHERN WI FOR TONIGHT.

EARLY MORNING CONVECTION OVER SOUTHERN WI AND NORTHERN IL LED TO A
SHALLOW COLD POOL DEVELOPING OVER NORTH CENTRAL IL THIS MORNING.
THIS IS LEADING TO A BIG DELAY IN SUNSHINE...ALONG WITH THE CURRENT
SHOWERS. THEREFORE...DROPPED THE MAX TEMPS INTO THE LOWER 80S IN THE
SOUTHWEST FORECAST AREA /RATHER THAN UPPER 80S/ AND AROUND 80
ELSEWHERE.

&&

.AVIATION/18Z TAFS/...

A NORTH TO SOUTH ORIENTED LINE OF THUNDERSTORMS IS TRACKING EAST
ACROSS SOUTH CENTRAL AND SOUTHEAST WI NOW THROUGH 2 PM. ONCE THESE
SHOWERS AND THUNDERSTORMS EXIT...NEW MODELS ARE INDICATING A LOWER
THREAT FOR ADDITIONAL SHOWERS AND TSTORMS DEVELOPING OVER SOUTHERN
WI THIS EVENING. THEREFORE...BACKED OFF ON TSRA IN THE TAFS.

CIGS OF CUMULUS CLOUDS WILL RANGE FROM 3.5-5.0 KFT TODAY BUT WITH
MUCH LOWERS CIGS AND VSBYS WITHIN TSTORMS. THE MOIST CONDITIONS WILL
LIKELY LEAD TO SOME FOG DEVELOPMENT LATE TONIGHT.

&&

.PREV DISCUSSION... /ISSUED 447 AM CDT THU AUG 21 2014/

TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.

850 MB WARM ADVECTION AND MOISTURE TRANSPORT HAS BEGUN OVER THE SW
CWA WHERE HEAVY RAINFALL IS CURRENTLY PRESENT. PWS ARE UP TO 1.8
INCHES AND WILL OVERSPREAD THE AREA TODAY. RADAR RAINFALL TOTALS ARE
OVER 2 INCHES WITH THE HP LIKE STORM THAT MOVED THROUGH LAFAYETTE
AND SW GREEN COUNTIES. THIS AREA OF TSTORMS WILL CONTINUE TO MOVE
SLOWLY ESEWD AND WEAKEN TOWARD SUNRISE AS DEPICTED BY THE HRRR
MODEL. THUS ONLY CHANCES OF RAIN THIS MORNING FOR THE MILWAUKEE
AREA.

OVER THE NEXT 18 HOURS THE STRONGEST PORTION OF THE LOW LEVEL
JET STREAM CURRENTLY OVER MN WILL GRADUALLY VEER INTO AND THROUGH
SRN WI. THIS WILL BRING THE SFC WARM FRONT INTO THE AREA WITH A
STRONG CAPE GRADIENT FROM SW TO NE ACROSS THE REGION. THUS EXPECT
THE SHOWERS AND TSTORMS OVER MN TO MOVE ACROSS THE AREA THIS
AFTERNOON WITH ADDITIONAL DEVELOPMENT EXPECTED ON ITS BACK EDGE FOR
THE EVENING HOURS. MLCAPE VIA WARM...MOIST ADVECTION WILL RISE TO
1000-2500 J/KG WITH 30-40 KTS OF DEEP LAYER SHEAR EXPECTED. IN
ADDITION THE 0-1 KM BULK SHEAR WILL INCREASE TO 15-20 KTS WITH 0-1
KM SRH OVER 100 M2/S2. THUS EXPECT ONE TO TWO SVR MCS/S BUT WITH THE
POTENTIAL FOR A FEW SUPERCELLS AS WELL. ALL SVR THREATS ARE POSSIBLE
AS HIGHLIGHTED IN SPC DAY 1 OUTLOOK. THERE WILL ALSO BE A FLASH
FLOOD THREAT ESPECIALLY FOR URBAN AREAS. THE MEAN STORM MOTION WILL
BE ESEWD OF 20-30 KTS BUT ANY HP SUPERCELLS WILL TRACK SELY AROUND
10 KTS. INCLUDED SVR AND HEAVY RAIN POTENTIAL IN THE GRIDS AND WILL
HIGHLIGHT IN THE HWO.

FRIDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM

A WARM AND WET PATTERN IS EXPECTED TO CONTINUE FROM FRIDAY INTO
THE FIRST PART OF NEXT WEEK. THERE IS SOME UNCERTAINTY WITH
PRECIP CHANCES FRIDAY...AS MODELS ARE UNDECIDED WITH THE LOCATION
OF THE LOW LEVEL FRONTAL BOUNDARY. KEPT SOME CHANCE POPS GOING PER
THE THE FARTHER NORTH AND WETTER MODELS.

WENT WITH MAINLY CHANCE POPS FROM SATURDAY THROUGH WEDNESDAY.
MODELS GENERALLY ARE BUILDING UPPER RIDGING INTO THE AREA THROUGH
AT LEAST SUNDAY. AFTER THAT...THE ECMWF AND CANADIAN FLATTEN OUT
THE FLOW...WITH THE GFS HANGING ONTO THE RIDGE AND WARMER AIR A
BIT LONGER. BY WEDNESDAY THOUGH...THE GFS HAS A STRONG TROUGH
MOVING THROUGH...WITH THE ECMWF BUILDING RIDGING BACK IN. QUITE A
SPREAD IN MODEL TEMPS BY MID-WEEK AS A RESULT. EVEN GIVEN THE
MODEL DIFFERENCES...A CONSENSUS APPROACH STILL SUPPORTS SOME POPS
EACH DAY.

IT LOOKS PRETTY WARM THROUGH AT LEAST SUNDAY...POSSIBLY INTO
MONDAY. COULD SEE SOME HEAT INDEX VALUES UP TO AROUND 100 AWAY
FROM LAKE MICHIGAN...MAINLY FRIDAY AND SUNDAY. SHOULD SEE TEMPS
COOL A TAD BY TUE/WED...THOUGH POSSIBLY STILL A FEW DEGREES ABOVE
NORMAL.

AVIATION/12Z TAFS/...KMSN AND THE SE WI TAF SITES WILL SEE A ROUND
OF LIGHT TO MODERATE RAIN SHOWERS OR TSTORMS THIS MORNING WITH THE
STRONGEST STORMS STAYING TO THE SOUTH. A FEW AREAS OF LOW STRATUS
AND 3-5SM BR WILL OCCUR THIS AM AND MAY AFFECT THE TAF SITES. MORE
NUMEROUS TSTORMS ARE THEN EXPECTED FOR THIS AFTERNOON AND TNT AS A
WARM FRONT LIFTS NORTH INTO SRN WI. 2-3 ROUNDS OF TSTORMS ARE
POSSIBLE. CIGS OF CUMULUS CLOUDS WILL RANGE FROM 3.5-5.0 KFT BUT
WITH MUCH LOWERS CIGS AND VSBYS WITHIN TSTORMS. ONCE THE MAJORITY OF
THE TSTORMS HAVE ENDED LATE TNT...THE MOIST CONDITIONS WILL LIKELY
LEAD TO SOME FOG DEVELOPMENT.


&&

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

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
FRIDAY THROUGH WEDNESDAY...DDV



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