Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
000
FXUS63 KMKX 300151
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
851 PM CDT MON SEP 29 2014

.UPDATE...
MAIN CHALLENGE TONIGHT IS WITH SKY COVER...AND BY
ASSOCIATION...TEMPS. STRONG LOW LEVEL COLD AIR ADVECTION IS
GENERATING PLENTY OF LOW CLOUDS COVERING EASTERN AND SOUTHERN
WISCONSIN THIS EVENING. CLEARING CONTINUES OVER WEST CENTRAL
AREAS. THE CLEARING IS WITHIN A REGION OF STRONG SUBSIDENCE/DRYING IN
THE WAKE OF A DEPARTING STRONG SHORT WAVE. THAT SUBSIDENCE MOVES
OVER EASTERN WISCONSIN OVERNIGHT...BUT IT APPEARS THE LOW LEVEL
COLD ADVECTION WILL HAVE THE GREATER INFLUENCE AND KEEP THE
CLOUDS IN TIGHT ACROSS MUCH OF THE FORECAST AREA INTO TUESDAY
MORNING. THOUGH SOME OF OUR WESTERN FORECAST AREA COULD SEE SOME
CLEARING OVERNIGHT. CLEARING SHOULD EVENTUALLY WORK BACK INTO THE
AREA ON TUESDAY. WILL LEAVE TEMPS ALONE FOR NOW AS THEY STILL LOOK
GOOD WHEN COMPARED TO THE SHORT RANGE MODEL GUIDANCE AND THE
CLOUDY SKIES.

&&

.AVIATION/06Z TAFS/...
COLD AIR ADVECTION CONTINUES OVERNIGHT WITHIN A LOW LEVEL NORTH
TO NORTHEAST FLOW...KEEPING MAINLY MVFR CIGS LOCKED IN THROUGH
ABOUT MID MORNING ON TUESDAY...THEN SKIES SHOULD GRADUALLY SCATTER
OUT UNDER THE INFLUENCE OF HIGH PRESSURE. THERE COULD STILL BE
SOME POCKETS OF IFR CIGS MOVING THROUGH OVERNIGHT...ESPECIALLY
CLOSE TO LAKE MICHIGAN THROUGH ABOUT 12Z TUESDAY. WINDS WILL
STEADILY DIMINISH AS THE PRESSURE GRADIENT RELAXES OVERNIGHT.

&&

.MARINE...
THE SMALL CRAFT ADVISORY WILL CONTINUE THROUGH ABOUT MID-DAY ON
TUESDAY DUE TO BRISK WINDS AND HIGH WAVES. THE WINDS WILL SUBSIDE
OVERNIGHT...BUT THE WAVES WILL BE SLOW TO DIMINISH. HIGH PRESSURE
MOVING OVERHEAD WILL BRING IMPROVING CONDITIONS ON TUESDAY.

&&

.PREV DISCUSSION... /ISSUED 328 PM CDT MON SEP 29 2014/

TONIGHT AND TUESDAY - CONFIDENCE...MEDIUM

COLD FRONT CONTINUES TO SLIDE THROUGH SRN WI AND WILL EXIT TO THE
SOUTH BY EARLY THIS EVENING. FRONT HAS MOVED QUICKER DOWN THE LAKE
WHICH IS TYPICAL IN THESE SITUATIONS WITH THE GUSTIER NE WINDS
THERE. 88-D RADAR SHOWS LAKE INDUCED BOUNDARY RACING WESTWARD
MEETING UP WITH SOUTHWARD SAGGING EAST/WEST ORIENTED SYNOPTIC
BOUNDARY. HIGH PRESSURE RIDGE NOSES INTO SRN WI AS THE NIGHT WEARS
ALONG. POST FRONTAL SHRA BEING DRIVEN MORE BY MID LEVEL SHORTWAVE
AND NOSE OF UPPER SPEED MAX RATHER THAN LOWER LEVEL CONVERGENCE.
PRESSURE GRADIENT WILL KEEP NE WINDS GOING ...HIGHEST NEAR THE LAKE.
MUCH COOLER AIRMASS INVADING WHICH WILL DOMINATE INTO TUESDAY. 925
TEMPS BOTTOM OUT AT 3-5C BY 12Z...EURO EVEN A SMIDGE COLDER. THIS
SUGGESTS FURTHER LOWERING OF GOING MINS MAY BE NECESSARY IF WE CAN
CLEAR OUT THESE CLOUDS AND REALLY RAMP DOWN THE WINDS BUT FOR NOW
WILL KEEP LOWS CWA WIDE IN THE 40S. MID LEVEL RIDGING STARTS TO TAKE
HOLD WITH TIME THOUGH LINGERING CYCLONIC FLOW AND LOW LEVEL COLD
POOL LIKELY TO MAKE FOR STUBBORN CLOUD COVER EROSION IN PARTS OF THE
AREA. RIGHT NOW LLVL RH PROGS SUGGEST THIS WOULD BE MORE ACROSS THE
EASTERN CWA. HIGH TEMPS ONLY MID 50S TO MAYBE SOME LOW 60S IN THE
SOUTHWEST CWA.

TUESDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE - MEDIUM.

WEAK SHORT WAVE RIDGING AND DRY COLUMN EXPECTED TO KEEP QUIET
WEATHER CONTINUING INTO WEDNESDAY.  12Z GUIDANCE ALSO SHOWING
SLIGHLY SLOWER EWD PROGRESSION OF UPSTREAM TROUGH ON WED.  HOWEVER
DURING THE DAY...UPSTREAM LOW LEVEL JET AXIS DOES PIVOT EWD INTO WRN
WI.  ENOUGH MID-LEVEL WARM AIR AND MOISTURE RETURN TO WARRANT
KEEPING SMALLER POPS GOING ON WED OVER WRN CWA.

LOW TO MID LEVEL MOISTURE IN PLACE BY WEDNESDAY NIGHT AND THURSDAY
WITH PRECIPITABLE WATER VALUES APPROACHING 1.5 INCHES WHICH IS
APPROACHING 2 STANDARD DEVIATIONS FOR LATE SEPT.  STRONGEST LAYER Q-
VECTOR CONVERGENCE AFFECTS SRN WI WED NGT INTO THU AS LOW LEVEL JET
CONTINUES PIVOTING EWD ACROSS SRN WI.  ECMWF AND NAM IN BETTER
AGREEMENT ON STRENGTH OF LOW LEVEL JET. DURING THIS TIME...STRONGEST
PIECE OF MID-LEVEL ENERGY ALSO TRACKS NORTHEAST ACROSS SRN WI.
HENCE WL CONTINUE THE LIKELY WORDING WED NGT AND EXTEND INTO THU.
MAY BE A BREAK IN THE PRECIP LATER THU AS STRONGEST SYNOPTIC SCALE
FORCING SLIDES OFF TO THE EAST.  LATER SHIFTS WILL ADD GREATER
RESOLUTION TO PRECIP PERIODS FOR THU.

THURSDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE - MEDIUM.

EARLIER RUNS OF THE GFS HAD REMAINED AN OUTLIER CONCERNING SLOWER
EWD MOVEMENT AND STRONG AMPLIFICATION OF SOUTHERN STREAM SHORT WAVE
RESULTING IN CYCLOGENESIS OVER WRN GTLAKES...HOWEVER 12Z
DETERMINISTIC RUN HAS COME INTO BETTER AGREEMENT WITH OTHER MEDIUM
RANGE GUIDANCE.

OTHER MEDIUM RANGE GUIDANCE INCLUDING DGEX REMAINS MORE PROGRESSIVE
WITH SOUTHERN STREAM SHORT WAVE REMAINING WELL SOUTH OF THE AREA
INTO FRIDAY.  WILL FAVOR THIS SCENARIO DUE TO CONCENSUS.  NEVER THE
LESS...COLDER AIR STILL EXPECTED TO RETURN THU/THU NIGHT WITH
REINFORCING PUSH ON FRIDAY BEHIND SECONDARY MID-LEVEL SHORT WAVE
WHICH PHASES AND CONTRIBUTES TO AMPLIFICATION OF LONG-WAVE TROUGH
OVER GTLAKES FRI AND SAT.  85H TEMPS FALL FROM 10-12C ON THU TO
AROUND -2C ON SAT.  925H TEMPS FALL TO 0 TO 5C BY SAT.  TEMPS WL
MODERATE SLIGHTLY HEADING INTO EARLY NEXT WEEK AS THE UPPER FLOW
BACKS TO MORE NORTHWESTERLY.

TEMPERATURES WILL BE CHILLY FRIDAY NIGHT AND LIKELY TUMBLE INTO THE
MIDDLE 30S TO AROUND HOWEVER BOUNDARY LAYER MIXING SHOULD PREVENT
SIGNIFICANT FROST FORMATION.

LIGHTER WINDS ARE EXPECTED SATURDAY NIGHT HOWEVER EXPECTED CLOUDS
FROM PASSING WEAK DISTURBANCE SHOULD KEEP TEMPERATURES A LITTLE
WARMER.  HOWEVER IF MORE CLOUDS OCCUR...THE TEMPS MAY RAPIDLY DROP
INTO THE LOW TO MID 30S RESULTING IN A BETTER CHANCE FOR FROST.

WEAK LIFT WITH THIS NEXT SHORTWAVE MAY THEN BRING AREAS OF -RA TO
SRN WI ON SUN INTO SUN NGT AS LOW LEVEL THERMAL PROFILE WOULD
CONTINUE TO FAVOR LIQUID PRECIP.

CPC 6-10 AND 8-14 DAY OUTLOOKS VALID THROUGH EARLY OCT CONTINUE TO
SHOW 500MB HEIGHTS AVERAGING BELOW NORMAL.  SOME ENCOURAGEMENT FROM
LARGE POSITIVE ANOMOLY SETTING UP OVER WRN CONUS BY 00Z/10 WHICH
WOULD RESULT IN SEASONAL CONDITIONS RETURNING LATER IN THE WEEK.

AVIATION/00Z TAFS/...FRONT SHIFTING SOUTH OF SRN WI INTO EARLY
EVENING. WINDS HAVE BECOME GUSTY FROM THE NE CLOSER TO THE LAKE IN
THE WAKE OF THE FRONT. THIS WILL SLOWLY EASE AS THE NIGHT WEARS
ALONG AS HIGH PRESSURE RIDGES INTO THE STATE. MVFR STRATUS DECK WILL
CONTINUE SAGGING SOUTH INTO THE AREA AND WILL LIKELY LINGER INTO
EARLY TUESDAY WITH LOW LEVEL THERMAL TROUGH IN PLACE. BAND OF
SHOWERS ASSOCIATED WITH 500 MILLIBAR DCVA AND JET MAX WILL SWING
THROUGH SRN WI LATE THIS AFTN/EVE. LINGERING CYCLONIC FLOW ON
TUESDAY AND LOW LEVEL THERMAL TROUGH SUGGESTS SOME OF THE MVFR CLOUD
COVER IN THE ERN CWA MAY BE STUBBORN TO DEPART.

MARINE...EXTENDED SMALL CRAFT TO ACCOUNT FOR A LAG BETWEEN GUSTIER
NE WINDS AND WAVE CESSATION ESPECIALLY GIVEN THE ONSHORE COMPONENT.
NORTH WINDS WILL EASE LATER TONIGHT INTO TUESDAY BUT STILL SOME
HIGHER WAVES POSSIBLE BETWEEN 12-18Z.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 PM CDT TUESDAY FOR LMZ643>646.

&&

$$

UPDATE...DAVIS
TONIGHT/TUESDAY AND AVIATION/MARINE...COLLAR
TUESDAY NIGHT THROUGH MONDAY...MBK



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.