Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 212040
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
340 PM CDT THU AUG 21 2014

.TONIGHT...FORECAST CONFIDENCE MEDIUM.

FIRST OF ALL...THE MODELS ARE ALL OVER THE PLACE FOR WHERE THEY ARE
PLACING QPF AND STORMS TONIGHT. 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...WHICH IS DEVELOPING STORMS OVER EASTERN IOWA AND
TRACKING THEM ACROSS NORTHERN IL. THE 12Z REGIONAL CANADIAN MODEL
DEVELOPS STRONG THUNDERSTORMS THIS EVENING SINCE IT DID NOT PICK UP
ON THE MORNING CONVECTION AND CLOUDS AND IS NOT A REASONABLE
SOLUTION.

THE WRF-ARW AND WRF-NMM AND A COUPLE OF OTHER MODELS STILL SHOW
THUNDERSTORMS DEVELOPING OVER WEST CENTRAL WI THAT SLIDE SOUTHEAST
THROUGH SOUTHERN WI LATE THIS EVENING. KEPT CHANCE POPS IN FORECAST
TO COVER THIS SCENARIO. THERE IS CLEARING AND DESTABILIZATION GOING
ON OVER SOUTHEAST MN THIS AFTERNOON THAT COULD SUPPORT THIS
SCENARIO. IF THESE THUNDERSTORMS DEVELOP...THERE WOULD BE MODERATE
CAPE...SHEAR AND HELICITY TO SUPPORT A FEW STRONG UPDRAFTS AND
THEREFORE ISOLATED SEVERE HAIL AND WIND. WITH PRECIPITABLE WATER
VALUES AROUND 2 INCHES...EXPECT VERY HEAVY RAIN WITH ANY
THUNDERSTORMS.

BY FRIDAY MORNING...CONVECTION SHOULD BE SOUTH OF THE WI/IL BORDER
AS THE LOW LEVEL JET VEERS WEST. THE NAM AND GFS FCST SOUNDINGS ARE
SHOWING HIGH CAPE AND MODERATE SHEAR OVER SOUTH CENTRAL WI FRI
AFTERNOON. THE PROBLEM IS THAT THERE WILL BE A SMALL CAP. A FEW
MODELS DEVELOP CONVECTION ALONG A LAKE BREEZE...BUT THERE IS PLENTY
OF UNCERTAINTY. THE BETTER CHANCE FOR CONVECTION WILL BE CLOSER TO
THE SURFACE WARM FRONT WHICH SHOULD BE OVER IA/IL.

SOME EXPECTED SUNSHINE WILL ALLOW TEMPS TO REACH THEIR POTENTIAL
WITH 925MB TEMPS AROUND 25C...WITH MAX TEMPS IN THE UPPER 80S INLAND
AND LOWER 80S NEAR THE LAKE.

.SATURDAY - CONFIDENCE...MEDIUM
588DM 500 MILLIBAR RIDGE CONTINUES TO BE ANCHORED ACROSS THE
WESTERN GREAT LAKES. SHORTWAVE ENERGY IS FOCUSED IN THE
DAKOTAS/PLAINS. ASSOCIATED SURFACE LOW WILL BE IN THE PLAINS AS
WELL. A FRONTAL BOUNDARY WILL EXTEND EASTWARD FROM THE LOW...WITH
THE BEST FRONTAL CONVERGENCE PROGGD CLOSER TO WESTERN CWA. BEST
925/850 BAROCLINICITY LOCATED THERE. CORE OF 850 LLJ IS WELL WEST
BUT WRN CWA CLOSER TO THE INFLUENCE OF THIS FEATURE. 925 TEMPS
RANGE FROM 20C IN NE CWA TO AROUND 24C IN THE SW CWA. MEANWHILE
HOTTEST AIRMASS CONTINUES TO BUILD TO OUR SOUTHWEST WITH 925 TEMPS
DEEP IN INTO THE 20S CELSIUS. BEST CWASP NUMBERS WELL TO OUR WEST
WHERE BETTER DYNAMICS RESIDE.

.SUNDAY - CONFIDENCE...MEDIUM
UPPER RIDGE CONTINUES TO BUILD AND EXPAND EASTWARD THROUGH THE
REST OF THE GREAT LAKES REGION. 850 HOT PROD EXTENDS FURTHER
NORTHEAST WITH HOT AND HUMID AIRMASS ENCOMPASSING ALL OF THE AREA
WITH BEST BAROCLINICITY WELL TO OUR NORTH. 925 TEMPS PROGGD TO
RANGE FROM 25C IN THE ERN CWA TO 28C IN THE WRN CWA. SO EXPECTING
TO SEE PLENTY OF LOW TO MID 90S FOR HIGH TEMPS IN CNTRL AND WRN
CWA...OUTSIDE OF ANY LAKE INDUCED COOLING. IF SE WINDS BEND MORE
SOUTHERLY MAY NEED TO EXPAND HOTTER TEMPS FURTHER EAST WITHIN THE
CWA. CWASP NUMBERS FOCUS WELL TO OUR NORTHWEST CLOSER TO THE
STRONGER SOUTHWEST 500 MILLIBAR FLOW. SO WILL GO WITH A HOT/HUMID
AIRMASS WITH CONSIDERABLE CAPPING IN PLACE. GIVEN 90/70 DEGREE
TEMP/DEW POINT POTENTIAL MAY NEED A HEAT ADVISORY FOR SOME WITHIN
THE CWA.

.SUNDAY NIGHT THROUGH WEDNESDAY - CONFIDENCE...MEDIUM
UPPER RIDGE BREAKS DOWN AND LOOKS LIKE WE WILL TRANSITION INTO
MORE OF AN ACTIVE PATTERN...WITH SOUTHWEST UPPER LEVEL FLOW. WHILE
LEAD RIPPLES WITHIN THE FLOW MAY GENERATE STORMS WITH MEANDERING
FRONTAL BOUNDARY...THE 12Z ECMWF HAS TRENDED TOWARDS THE GFS WITH
A MORE PROMINENT TROUGH APPROACHING TOWARDS MIDWEEK. THE TUE/WED
PERIOD LOOKS INTERESTING...THOUGH STILL SOME TIMING DIFFERENCES
BETWEEN THE GFS/ECMWF WITH THE ECMWF TRENDING FASTER...GETTING THE
FRONT TO THE EAST BY MIDDAY WEDNESDAY.

.THURSDAY - CONFIDENCE...MEDIUM
EMCWF SHOWS SURFACE HIGH DOMINATING WITH DRY WEATHER WHILE THE
SLOWER SOLUTION OF THE GFS SUGGESTS SOME WRAPAROUND SHRA
POTENTIAL. WHILE SOME DIFFERENCES IN THE SYNOPTIC SETUP...BOTH ARE
LARGELY DRY. WILL STICK WITH THE ALLBLEND POPS BUT FINALLY SUGGEST
A BREAK FROM THE THUNDER POTENTIAL.

&&

.AVIATION/12Z TAFS/...THERE IS A CHANCE THAT ADDITIONAL THUNDERSTORMS
WILL DEVELOP OVER WEST CENTRAL WI EARLY THIS EVENING AND ROLL ACROSS
SOUTHERN WI LATE THIS EVENING. IF THAT DOES NOT HAPPEN...EXPECT
QUIET WEATHER FOR THE WHOLE NIGHT INTO FRIDAY MORNING. THE MOIST
CONDITIONS WILL LIKELY LEAD TO SOME FOG DEVELOPMENT LATE TONIGHT.
EARLY MORNING FOG AND LOW CEILINGS WILL GRADUALLY DISSIPATE AND
LIFT TO VFR BY MID FRIDAY MORNING.

THERE WILL BE UNSTABLE CONDITIONS AND SOME SUNSHINE FOR FRIDAY
AFTERNOON...BUT IT IS NOT CERTAIN THAT WE WILL SEE THUNDERSTORMS DUE
TO A SMALL CAPPING INVERSION AND LACK OF A STRONG FRONT. THE LAKE
BREEZE WILL NEED TO BE WATCHED FOR POTENTIAL CONVECTION FRIDAY
AFTERNOON.

&&

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

$$
TODAY/TONIGHT AND AVIATION/MARINE...MRC
FRIDAY THROUGH WEDNESDAY...COLLAR



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