Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 152031
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
331 PM CDT FRI AUG 15 2014

.TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM.

MODELS LOOK TO KEEP MOST OF THE AREA DRY TONIGHT...AS MAIN SURFACE
LOW AND 500 MB SHORTWAVE TROUGH REMAIN TO THE SOUTHWEST OF THE AREA.
AREA FORECAST SOUNDINGS ARE NOT SHOWING MUCH MOISTENING THROUGH A
DEEP LAYER OF THE AIR COLUMN. THINK THAT SOME MIDDLE TO HIGH CLOUDS
WILL MOVE INTO THE AREA ON THE PERIPHERY OF THE SYSTEM TO THE
SOUTHWEST. DID KEEP LOW POPS IN THE FAR SOUTHWEST LATER TONIGHT TO
BLEND WITH NEIGHBORING OFFICES...THOUGH THIS AREA COULD REMAIN DRY
AS WELL.

LIGHT WINDS AND MOISTURE MOVING INTO THE AREA SHOULD LEAD TO SOME
FOG DEVELOPMENT IN THE WISCONSIN RIVER VALLEY AND OTHER LOW SPOTS.
THINK THAT THERE WILL BE ENOUGH CLOUDS TO LIMIT AREAL EXTENT OF ANY
FOG TO THE LOW SPOTS. LOWS IN THE UPPER 50S TO LOWER 60S SEEM
REASONABLE FOR TONIGHT.

KEPT LOW POPS ALONG THE ILLINOIS BORDER AREAS SATURDAY...GIVEN
RELATIVELY CLOSE SURFACE LOW MOVING EAST INTO ILLINOIS. 500 MB
SHORTWAVE TROUGH REMAINS SOUTHWEST OF THE AREA DURING THIS TIME.
SHOULD SEE MORE LOW LEVEL MOISTURE AND CLOUDS DEVELOP...WITH
CONTINUED MOISTURE ADVECTION INTO THE AREA.

COLD FRONT WILL THEN SHIFT SOUTHWARD TOWARD THE FAR NORTHERN
COUNTIES BY 00Z SUNDAY. ENOUGH LOW LEVEL MOISTURE AND MEAN LAYER
CAPE DEVELOPS TO BRING CHANCES FOR SHOWERS AND STORMS IN THE
NORTHERN COUNTIES LATER IN THE AFTERNOON. WARM AND HUMID CONDITIONS
ARE EXPECTED...WITH HIGHS IN THE UPPER 70S TO LOWER 80S IN MOST
AREAS.

.SHORT TERM...SATURDAY NIGHT THROUGH MONDAY.

SATURDAY NIGHT...FORECAST CONFIDENCE HIGH.

12Z NAM NOW MORE IN LINE WITH OTHER MODELS TAKING 500 MB SHORT WAVE
AND 700-850 MB LOWS FARTHER SOUTH INTO CENTRAL IL...WITH THE
INVERTED SURFACE TROUGH EXTENDING UP THE MS RVR VALLEY AT 00Z SUNDAY
CONSOLIDATING NEAR QUINCY IL BY 06Z AND MOVING SOUTH INTO SRN IL BY
18Z SUNDAY. THIS ALLOWS THE SURFACE HIGH TO BUILD WELL SOUTH INTO WI
AND TAKE THE SURFACE COLD FRONT TO THE IL/WI BORDER BY 12Z SUNDAY.
WILL TRACK POP CHANCES WITH LOW-LAYER FRONTOGENETIC FORCING AS IT
MOVES NORTH TO SOUTH WITH FRONT. WITH FRONT DROPPING THROUGH AT A
DIURNALLY UN-FAVORED TIME...WILL KEEP POPS IN CHANCE CATEGORY FOR
NOW.

SUNDAY...FORECAST CONFIDENCE MEDIUM

THE 12Z NAM SEEMS TO BE SENSITIVE TO A COMBINATION OF WEAK SFC
FRONTOGENESIS WITH LAKE SHORE CONVERGENCE AND DIFFERENTIAL CVA WITH
VERY WEAK VORTICITY STREAMER TRAILING FROM SHORT WAVE MOVING THROUGH
THE EASTERN GREAT LAKES IN THE EASTERN CWA. 12Z NAM GENERATING
SPOTTY LIGHT QPF OVER EAST CENTRAL WISCONSIN WHILE THE OTHER MODELS
ARE DRY. VERY LITTLE INSTABILITY...WITH GFS AND NAM FORECAST
SOUNDINGS SHOW SOME MOISTURE TRAPPED UNDER SUBSIDENCE INVERSION
AROUND 2K FT IN WAKE OF COLD FRONT PASSAGE THAT THE GFS MIXES OUT BY
18Z...BUT THE NAM HOLDS ONTO FOR MOST OF THE DAY. MOIST LAYER ON THE
NAM IS SHALLOW SO ONLY DRIZZLE EXPECTED AT MOST...AND TOO LOW A
PROBABILITY TO ADD AT THIS TIME.

925MB COOL POCKET SETTLES OVER WISCONSIN WITH DEEP MIXING ALLOWING
TEMPS TO REACH THE MID 70S...WITH A FEW UPPER 70S...IN THE WEST
WHILE EASTERN LOCATIONS STRUGGLE TO REACH 70 UNDER 14C 925 MB TEMPS
AND NORTHEAST WINDS.

.SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH.

HIGH PRESSURE TO DOMINATE THIS PERIOD...WITH 12Z GEM THE ONLY MODEL
TO GENERATE LIGHT QPF MONDAY MORNING IN CVA AHEAD OF WEAKENING
SHEARED VORTICITY MAX EJECTING OUT AHEAD OF MAIN SHORT WAVE TROUGH.
WILL SIDE WITH DRY SOUNDINGS AND MAJORITY OF THE MODELS AND KEEP
PCPN OUT.

GREAT RADIATIONAL COOLING CONDITIONS WILL BRING LOW TEMPERATURES
DOWN A FEW DEGREES BELOW BLENDED GUIDANCE NUMBERS SUNDAY NIGHT. WARM
AIR ADVECTION IN RETURN FLOW AHEAD OF THE NEXT WAVE WILL PUSH 925 MB
TEMPERATURES TO NEAR 20C IN THE WEST BY LATE IN THE AFTERNOON.
EASTERLY WINDS WILL KEEP EASTERN SECTIONS LOWER.

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE LOW

SHOWERS AND THUNDERSTORMS MOVE IN MONDAY NIGHT WITH SHORT WAVE
TROUGH THAT LINGERS ACROSS WESTERN GREAT LAKES REGION WITH WEAK FLOW
ALOFT. VARYING SOLUTIONS TO PLACEMENT...CONFIGURATION AND STRENGTH
OF THE WAVE AND THE BROAD AREA OF SURFACE LOW PRESSURE UNDERNEATH
LEADS TO CHANCE POPS ALMOST EVERY PERIOD.

GEM AND ECMWF INDICATING THE SHORT WAVE TROUGH LIFTING FAR ENOUGH TO
THE NORTHEAST AND THE SURFACE LOW WASHING OUT TO BRING A BREAK IN
THE PCPN TUESDAY NIGHT AND WEDNESDAY. THOUGH DIFFERENCES
CONTINUE...EITHER GFS OR ECMWF SOLUTIONS WILL BRING PCPN CHANCES
BACK THURSDAY INTO FRIDAY. NEAR-NORMAL BLENDED TEMPERATURES LOOK
REASONABLE FOR THE EARLY EXTENDED BUT MAY BE A BIT TOO WARM FOR
THURSDAY WITH EXPECTED PCPN...AND FOR FRIDAY IF THE COOLER ECMWF
VERIFIES.


&&

.AVIATION/00Z TAFS/...

VFR CONDITIONS ARE EXPECTED THIS EVENING...WITH DRY AIRMASS IN PLACE
OVER THE AREA. SCATTERED TO BROKEN DIURNAL CUMULUS CLOUDS SHOULD
LINGER UNTIL EARLY EVENING. LAKE BREEZE WITH LIGHT SOUTHEAST WINDS
SHOULD REACH MILWAUKEE AND KENOSHA BY 22Z TO 23Z THIS AFTERNOON.

SOME MIDDLE TO HIGH CLOUDS SHOULD SPREAD ACROSS THE AREA TONIGHT.
LIGHT WINDS AND INCREASING MOISTURE MAY LEAD TO MVFR FOG AT MADISON
AND KENOSHA BETWEEN 10Z AND 13Z SATURDAY. LEFT VFR IN TAFS FOR NOW
DUE TO SOME UNCERTAINTY GIVEN EXPECTED CLOUDS.

VFR CONDITIONS SHOULD THEN PREVAIL THROUGH SATURDAY...ON LIGHT
SOUTHWEST WINDS. CHANCES FOR SHOWERS AND A FEW STORMS IN THE LATE
AFTERNOON AND EVENING...AS COLD FRONT MOVES SOUTHWARD INTO THE AREA.
MAY USE VICINITY SHOWER/THUNDER WORDING IN TAFS AFTER 21Z
SATURDAY.

&&

.MARINE...

GUSTY NORTH TO NORTHEAST WINDS OF 10 TO 20 KNOTS ARE EXPECTED BEHIND
COLD FRONTAL PASSAGE SATURDAY EVENING ACROSS THE NEARSHORE WATERS.
COULD SEE A FEW GUSTS TO 22 KNOTS OR GREATER...THOUGH MOST GUSTS
SHOULD REMAIN BELOW THIS THRESHOLD. THIS WILL GENERATE WAVES OF 2 TO
4 FEET SATURDAY NIGHT INTO EARLY SUNDAY. THE WINDS AND WAVES WILL
GRADUALLY SUBSIDE BY SUNDAY NIGHT.

&&

.BEACHES...

COULD SEE A MODERATE SWIM RISK SATURDAY NIGHT INTO SUNDAY ACROSS THE
BEACHES ALONG LAKE MICHIGAN...GIVEN 2 TO 4 FOOT WAVES AND GUSTY
NORTH TO NORTHEAST WINDS OF 10 TO 20 MPH. A FEW GUSTS TO 25 MPH ARE
POSSIBLE. &&

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

$$

TONIGHT/SATURDAY AND AVIATION/MARINE...WOOD
SATURDAY NIGHT THROUGH FRIDAY...REM


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