Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 140229
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
929 PM CDT MON APR 13 2015

.UPDATE...


&&

.AVIATION/06Z TAFS/...

VFR CONDITIONS AS HIGH PRESSURE MOVES ACROSS SOUTHERN WISCONSIN.
SKC WITH SCATTERED CIRRUS AT TIMES.


&&

.PREV DISCUSSION... /ISSUED 317 PM CDT MON APR 13 2015/

TONIGHT...FORECAST CONFIDENCE HIGH

MID-LEVEL TROUGH AXIS...INITIALLY OVER THE WESTERN GREAT LAKES
REGION THIS AFTERNOON...SHIFTS EAST TONIGHT. MID-LEVEL HEIGHTS
BEGIN RISING AS LOW AMPLITUDE RIDGING BUILDS INTO THE REGION.
STRONG SUBSIDENCE CONTINUES ALOFT AS NVA POCKET MOVES THROUGH
OVERNIGHT. SURFACE HIGH PRESSURE...NOW OVER THE CENTRAL
PLAINS...MIGRATES INTO THE LOWER MISSOURI VALLEY TONIGHT WITH
RIDGING WORKING INTO THE CWA FROM THE SOUTHWEST. INITIALLY GUSTY
WINDS THIS EVENING WILL SUBSIDE OVERNIGHT WITH THE DEVELOPMENT OF
AN INVERSION IN THE SURFACE LAYER. WITH DRY AIR...AND WEAK
WINDS...LOWS WILL DROP INTO THE 30S FOR MOST LOCATIONS AWAY FROM
THE LAKESHORE.

TUESDAY...FORECAST CONFIDENCE HIGH

DEEP LAYER RIDGING WILL PREVAIL...WITH SURFACE HIGH PRESSURE
SLIDING EAST ACROSS THE CWA DURING THE AFTERNOON. SUBSIDENCE
INVERSION BREAKS DURING THE LATE MORNING WITH MIXING HEIGHTS
RISING TO AROUND 800 MB BY MID AFTERNOON. WINDS WILL BE FAIRLY
WEAK WITH HIGH PRESSURE IN CONTROL...BUT EXPECT DEWPOINTS TO TANK
DURING THE AFTERNOON...LIKELY DROPPING INTO THE LOWER TO MIDDLE
20S...POTENTIALLY LOWER...ACROSS THE WESTERN AND NORTHERN CWA.
TEMPERATURES WILL WARM QUICKLY AFTER THE INVERSION BREAKS...WITH
AREAS AWAY FROM THE LAKE CLIMBING WELL INTO THE 60S...AND WESTERN
LOCATIONS POTENTIALLY CRACKING 70. EASTERLY WIND COMPONENT DURING
THE AFTERNOON WILL KEEP READINGS A BIT COOLER FROM ROUGHLY WEST
BEND TO WAUKESHA AND POINTS EAST.

SHORT TERM...TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...FORECAST
CONFIDENCE MEDIUM

SFC HIGH PRESSURE REMAINS IN CONTROL TUESDAY NIGHT AS A BAND OF
500MB NEGATIVE VORTICITY ADVECTION AND MID-LEVEL RIDGING WILL
KEEP CONDITIONS ACROSS S WI QUIET. TEMPERATURES LOOK TO BE ON THE
CHILLY SIDE THANKS TO LIGHT WINDS AND RADIATIONAL COOLING...AS
LOWS WEDNESDAY MORNING LOOK TO BE IN THE UPPER 30S TO LOWER 40S.
SKIES LOOK TO BE RELATIVELY CLEAR TUESDAY AND WEDNESDAY AS NAM AND
GFS MODEL BUFKIT SOUNDINGS SHOW VERY DRY CONDITIONS THROUGH THE
COLUMN DURING THIS TIME.

A BIT OF UNCERTAINTY EXISTS REGARDING CHANCES FOR PRECIPITATION
LATER IN THE DAY WEDNESDAY AS THE GFS IS STAYING DRY...WHILE THE
ECMWF AND THE SREF ENSEMBLES ARE SHOWING SOME QPF WITH A WEAK
500MB SHORTWAVE TROUGH AND WEAK 850MB Q-VECTOR CONVERGENCE
TRANSLATING THROUGH THE REGION. KEPT SLIGHT CHC/CHC POPS IN THE
GRIDS TO COLLABORATE WITH NEIGHBORING OFFICES ALTHOUGH CONFIDENCE
IS NOT HIGH WITH SEEING ANY PRECIPITATION FROM THIS SYSTEM DUE TO
ITS WEAK NATURE...AND THE GFS AND NAM TRENDING TOWARDS DRIER
CONDITIONS.

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

THE WEAK 500MB SHORTWAVE TROUGH CONTINUES ACROSS THE REGION
THURSDAY...KEEPING CHANCES OF PRECIPITATION IN THE AREA. THIS
TROUGH SHOULD MOVE OUT OF THE AREA BY LATE IN THE DAY THURSDAY.

UNCERTAINTY STILL EXISTS IN THE MODELS REGARDING PRECIPITATION
CHANCES FRIDAY AND SATURDAY. THE 13.12Z GFS IS TRENDING DRIER
COMPARED TO THE 13.06Z GFS. IN FACT...THE 13.12Z GFS IS SHOWING NO
PRECIPITATION UNTIL LATER IN THE DAY FRIDAY WHEN A WEAK BAND OF
FRONTOGENETICAL FORCING MOVES THROUGH THE REGION. THE ECMWF DRIES
OUT FASTER THAN THE GFS WITH THE SYSTEM MOVING OUT BY 06Z
SATURDAY...WHILE THE GFS KEEPS QPF AMOUNTS IN THE FORECAST AREA
THROUGH 12Z SATURDAY. KEPT SLIGHT CHANCES POPS IN THE GRIDS AS
BOTH MODELS ARE SHOWING AGREEMENT IN THE PLACEMENT OF THE
FRONTOGENETICAL BAND.

BY SATURDAY MORNING...THE GFS AND ECMWF ARE PROGGING QUIET
WEATHER TO RETURN AS ANOTHER HIGH PRESSURE SYSTEM TRANSLATES
THROUGH THE UPPER MIDWEST.

BY SUNDAY AFTN INTO MONDAY...THE GFS SOLUTION IS PROGGING A 700
MB CUT-OFF LOW OVER THE SOUTHERN GREAT PLAINS AND EVENTUALLY
MAKING ITS WAY INTO THE GREAT LAKES REGION. THE ECMWF IS NOT
RESOLVING THE CUT-OFF LOW LIKE THE GFS IS...ALTHOUGH THE ECMWF IS
SHOWING A MORE BROAD ZONE OF PRECIPITATION ALONG WITH A DECENT
DEFORMATION ZONE. THE ECMWF SOLUTION IS A LITTLE SLOWER THAN THE
GFS SOLUTION AS WELL...SO SOME UNCERTAINTY EXISTS WITH THIS
SUNDAY/MONDAY SYSTEM.

AVIATION/00Z TAFS/...VFR CONDITIONS THROUGH THE TAF PERIOD. SCT
CU AT 6-8 KFT WILL DISSIPATE BY 00Z. SKC AFTER THAT. STRONG
WESTERLY WINDS AROUND 15 KT WILL CONTINUE GUSTING UP TO 25 KT
THROUGH THE AFTERNOON BEFORE SUBSIDING TO AROUND 10 KT AT 01Z.
LIGHTER WINDS AND SKC ON TUE WITH HIGH PRESSURE IN CONTROL.

MARINE...AFTER AN EARLY MORNING LULL...GUSTY WESTERLY WINDS HAVE
INCREASED ACROSS THE NEARSHORE WATERS THIS AFTERNOON. MESOSCALE
MODELS SUGGEST ELEVATED WINDS CONTINUING THROUGH 00Z.
THEREAFTER...PRESSURE GRADIENT RELAXES WITH LOW-LEVEL INVERSION
DEVELOPING. THUS...SMALL CRAFT ADVISORY CONTINUES WITH THE 01Z/8PM
EXPIRATION TIME LOOKING GOOD.

&&

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

$$

UPDATE...HENTZ
TONIGHT/TUESDAY AND AVIATION/MARINE...SPM
TUESDAY NIGHT THROUGH MONDAY...JTS



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