Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 190238
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
938 PM CDT THU SEP 18 2014

.UPDATE...TRICKY FORECAST FOR THE OVERNIGHT HOURS. DEWPOINTS ABOUT
5 DEGREES WARMER THAN PAST SEVERAL DAYS WHEN PATCHY FOG DEVELOPED
OVERNIGHT. MOIST LIGHT ELY FLOW TO CONTINUE OVERNIGHT. BOUNDARY
LAYER WINDS ARE EXPECTED TO INCREASE TO 15 TO 25 KNOTS AT AND
EVEN SLIGHTLY BELOW INVERSION OF 1-2K FEET. TAMDAR ASCENT SOUNDING
FROM KMKE AT 0127Z SHOWED LIGHT WINDS BLO 10KTS UP TO INVERSION AT
2K FEET. THINK A MIX OF STRATUS AND FOG WL DEVELOP OVERNIGHT.
POSSIBLE THAT SMALL AREA OF STRATUS AROUND 1K FEET OVER SE WI MAY
EXPAND NEXT SEVERAL HOURS. FOG WL LIKELY BE LOCALLY DENSE BUT TOO
MUCH UNCERTAINTY REGARDING POSSIBLE STRATUS AND MIXY WINDS BLO
INVERSION TO ADD DENSE FOG TO THE FORECAST AT THIS POINT. HOWEVER
BEEFED UP PATCHY/AREA WORDING FOR THE OVERNIGHT. LOWERED TEMPS
MOST LOCATIONS A DEGREE OR TWO.

&&

.AVIATION/06Z TAFS/...EXPECT A BLEND OF STRATUS AND FOG OVERNIGHT
BUT A LOT OF UNCERTAINTY REGARDING EXTENT. VSBYS LIKELY TO DROP TO
IFR OR LOWER MOST LOCATIONS. SEE ABOVE UPDATE FOR MORE SPECIFICS.

&&

.MARINE...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM LATE MORNING
FRIDAY NORTH OF PORT WASHINGTON AND FROM EARLY AFTERNOON ACROSS
THE REMAINDER OF THE NEAR SHORE MARINE ZONES. TIGHTENING PRESSURE
GRADIENT AHEAD OF COLD FRONT IN THE NORTHERN PLAINS AND HIGH
PRESSURE OVER THE EASTERN GTLAKES WILL RESULT IN SOUTH WIND GUSTS
REACHING SMALL CRAFT ADVY LEVELS ON FRIDAY...CONTINUING INTO
SATURDAY.

&&

.PREV DISCUSSION... /ISSUED 337 PM CDT THU SEP 18 2014/

TONIGHT AND FRIDAY...FORECAST CONFIDENCE HIGH.

CLOUDS QUICKLY ERODED AWAY THIS AFTERNOON WITH MIXING. THE ONLY
CLOUDS HANGING AROUND YET THROUGH 330 PM ARE IN THE FAR EAST. EXPECT
THESE TO SCATTER OUT BY EARLY EVENING WITH HIGH PRESSURE OVER THE
AREA. CLEAR SKIES AND LIGHT WINDS WILL ALLOW FOR PATCHY LIGHT FOG
ONCE AGAIN.

WINDS WILL QUICKLY INCREASE OUT OF THE SOUTHEAST FRIDAY MORNING AND
VEER TO THE SOUTH MIDDAY. GUSTS TO 30 MPH WILL BE POSSIBLE. SKIES
WILL BEGIN CLEAR IN THE MORNING AND THEN PLAN ON INCREASING HIGH
CLOUDS DURING THE AFTERNOON AS A LOW PRESSURE TROUGH APPROACHES FROM
THE NORTHERN PLAINS. STEADY 925-850MB WARM AIR ADVECTION WILL ALLOW
FOR HIGHS TO RISE INTO THE LOWER TO MID 70S.

SHORT TERM...FRIDAY NIGHT THROUGH SUNDAY NIGHT

FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE HIGH.

KEPT POPS MAINLY IN THE CHANCE CATEGORY FRIDAY NIGHT AS FORCING WITH
LOW-LEVEL JET AHEAD OF THE SHORT WAVE TROUGH IS STRONGEST TO THE
NORTH AND WEST...CLOSER TO SURFACE LOW AND TRAILING COLD
FRONT/SURFACE TROUGH...THEN WEAKENS AS 850 MB WINDS HEEL OVER AND
LOWER BETWEEN 06Z AND 12Z SATURDAY. DID KEEP LIKELY POPS IN THE FAR
NORTH WHERE THERE IS A WEAK 850 MB CONVERGENCE MAX AS FLOW IS CROSS-
ISOTHERMAL OVER NOSE OF THE 850 MB THERMAL RIDGE.  SOUTHERLY WINDS
AHEAD OF FRONT WILL HOLD OVERNIGHT LOWS IN THE 60S WITH A FEW UPPER
50S IN THE EAST INLAND FROM THE LAKE.

BETTER CHANCES FOR PCPN COME SATURDAY AFTERNOON/EVENING AS THE FRONT
AND A LEAD SHORT WAVE TROUGH MOVE THROUGH THE SRN PORTION OF THE
STATE...ESPECIALLY IN THE SOUTHEAST...WHERE LOW-MID LEVEL
FRONTOGENETIC RESPONSE IS STRONGEST. TEMPS WARM INTO THE MID-UPPER
70S WITH MID-60S DEW POINTS AHEAD OF THE FRONT. POTENTIAL FOR SEVERE
WEATHER PREDICATED ON CIN DIMINISHING BEFORE THE FRONTAL PASSAGE AS
A NARROW CORRIDOR OF SURFACE-BASED CAPE IN THE 1000-1500 J/KG RANGE
DEVELOPS AHEAD OF THE FRONT. EFFECTIVE SHEAR RISES TO 30-40 KTS AT
THIS TIME WHICH WOULD BE SUFFICIENT TO SUPPORT AT LEAST A FEW STRONG
THUNDERSTORM UPDRAFTS CAPABLE OF PRODUCING HAIL AND GUSTY WINDS PER
SPC DAY 3 OUTLOOK.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE MEDIUM.

FRONT AND WIDESPREAD PCPN PUSH SOUTHEAST OF FORECAST AREA SATURDAY
EVENING...WITH A SECOND POCKET OF SHOWERS AND A FEW THUNDERSTORMS
CROSSING NRN WI OVERNIGHT AHEAD OF POTENT VORT MAXES THAT DIG THE
500 MB TROUGH DEEPER INTO THE STATE. MODELS DIFFER WITH SRN EXTENT
OF FORCING WITH THE DIGGING TROUGH AND A WEAK SECONDARY SURFACE
TROUGH...WHICH LEADS TO DIFFERENCES IN PCPN CHANCES. WILL FOLLOW A
BLENDED SOLUTION THAT KEEP SLIGHT CHANCE POPS IN THE NRN COUNTIES
AND FAR EAST OVERNIGHT...AND IN THE NORTHEAST CORNER SUNDAY. CLOUDS
AND 850 MB TEMPS STILL IN THE +8C TO +10C RANGE BRINGS LOWS IN THE
MID-UPPER 50S...WITH 925 MB TEMPS YIELDING HIGHS IN THE LOW 70S SW
AND UPPER 60S IN THE NE.

SKIES CLEAR AND PCPN CHANCES END AS HIGH PRESSURE BUILDS ACROSS
SUNDAY NIGHT....WITH LOWS IN THE 40S AWAY FROM LAKE MICHIGAN.

LONG TERM...MONDAY THROUGH THURSDAY. FORECAST CONFIDENCE HIGH.

SURFACE HIGH TO DOMINATE THE EXTENDED...WITH ONLY THE GFS SHOWING A
WEAK AND DRY BACK-DOOR COLD FRONT DROPPING THROUGH THE GREAT LAKES
MONDAY NIGHT AND TUESDAY. OTHERWISE DRY WEATHER THROUGH THE WEEK
WITH TEMPERATURES EARLY IN THE WEEK IN THE UPPER 60S FOR HIGHS AND
MID-UPR 40S FOR LOWS...SLOWLY WARMING TO AROUND 50 FOR LOWS
WEDNESDAY NIGHT AND THE LOWER 70S FOR HIGHS NEXT THURSDAY.


AVIATION/00Z TAFS/...

IFR CLOUDS ARE WILL CONTINUE TO SCATTER OUT OVER FAR EASTERN
WI/LAKESHORE LATE THIS AFTERNOON. CLEAR SKIES AND LIGHT WINDS WILL
ALLOW FOR ANOTHER NIGHT OF PATCHY FOG...MAINLY THE MVFR VARIETY.

LOOK FOR GUSTY SOUTH WINDS BEGINNING BY MID FRIDAY MORNING. GUSTS TO
28 KNOTS WILL BE POSSIBLE DURING THE AFTERNOON...ESPECIALLY NORTH OF
MADISON AND MILWAUKEE.

MARINE...

HIGH PRESSURE RETREATING TO THE EAST AND A LOW PRESSURE/COLD FRONT
APPROACHING FROM THE WEST WILL BRING SMALL CRAFT ADVISORY CONDITIONS
FRIDAY THROUGH SATURDAY DUE TO BREEZY SOUTHERLY WINDS. THE HIGHEST
WAVES WILL BE LOCATED NORTH OF MILWAUKEE. A SMALL CRAFT ADVISORY IS
IN EFFECT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 PM FRIDAY TO 4 PM CDT SATURDAY FOR
     LMZ644>646.

     SMALL CRAFT ADVISORY FROM 9 AM FRIDAY TO 4 PM CDT SATURDAY FOR
     LMZ643.

&&

$$

UPDATE...MBK


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