FXUS63 KMKX 250926
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
326 AM CST WED NOV 25 2009
.DISCUSSION...FORECAST FOCUS IS ON COMPLEX SYSTEM FOR TONIGHT INTO
EARLY THANKSGIVING DAY.
TODAY-
WATER VAPOR/RUC COMBO SHOWS CENTER OF CIRCULATION IN NORTHERN
ILLINOIS. CLOSED CIRCULATION EVOLVES INTO OPEN WAVE AND LIFTS
NORTHEAST THIS MORNING. FOCUSED PRECIP ASSOCIATED WITH DECENT 700
OMEGA AND DEFORMATION ZONE EXPECTED TO BECOME LESS ORGANIZED WITH
TIME. STILL NEED SOME PRETTY HEFTY POPS THIS MORNING EVEN THOUGH
QPF BECOMES LESS ORGANIZED. A BRIEF SHORTWAVE RIDGE TAKES
HOLD...BUT VERY BRIEF. NEXT UPPER LOW DROPS INTO SOUTHERN IOWA BY
00Z THURSDAY. 700 MILLIBAR LOW MOVES INTO EASTERN IOWA THIS
AFTERNOON. APPRECIABLE FORCING NOTED IN THE SOUTHWEST HALF OF THE
CWA AS A RESULT. HAVE CATEGORICAL POPS THIS AFTERNOON IN THE SW
WITH LESSER POPS NE.
TONIGHT-
THE CLEAR CHALLENGE RESTS IN THIS PERIOD AND WHAT TO DO WITH PRECIP
TYPE. THE COLD INFLUX THAT WAS EARLIER SLATED TO INVADE THE WESTERN
CWA IS NOW DIVING FURTHER SOUTH WHILE AN 850 THERMAL RIDGE WRAPS
INTO THE CWA FROM THE EAST. THE 12Z NAM HAD 850 TEMPS DOWN TO -4C
AND NOW THE COLDEST IS -2C. LOOKING OVER THE BUFKIT SOUNDINGS
THE POTENTIAL FOR FROZEN PRECIP HAS DIMINSIHED CONSIDERABLY. ALSO
THE CROSSHAIRS SIGNATURE SHOWS DECENT OMEGA WITHIN THE SNOW GROWTH
REGION HOWEVER THE BEST RH LIES BENEATH THE OVERLAY...AND THE
POTENTIAL FOR CONVECTION IS ROOTED ABOVE THE SNOW GROWTH REGION.
THE UPPER LOW TRACK IS FURTHER SOUTH ON THE GFS. STILL CONCERNED THOUGH...
THE 700 MILLIBAR FORCING AND DEFORMATION ZONE REMAINS IMPRESSIVE.
IF THE COLUMN WERE TO COOL QUICKER THAN WHAT MODELS SUGGEST...SNOW
AMOUNTS WOULD OBVIOUSLY BE IN THE NEIGHBORHOOD OF WHAT WAS
PREVIOUSLY THOUGHT. FOR NOW...WILL STEER TOWARDS WHAT THE BULK OF
EVIDENCE IS SUGGESTING WITH RESPECT TO THE LOW LEVEL THERMAL
PROFILE AND TREND SNOW AMOUNTS DOWN...GOING WITH A MIX IN THE
WEST AFTER MIDNIGHT.
THURSDAY-
SURFACE/850 TROUGHS MOVE EAST OF THE STATE WITH SOME PRECIP
LINGERING IN DEFORMATION ZONE. ECMWF SHOWING HIGHER QPF IN THE
SOUTHEAST. SOUNDINGS FROM ECMWF/GFS AND NAM SHOW MILWAUKEE COULD
STAY ALL RAIN TIL CONCLUSION OF EVENT. HOWEVER WILL BRING SOME
TRANSITION TO A MIX FURTHER EAST. DRIER AIR STARTS TO WORK IN FOR
THE AFTERNOON.
FRIDAY-
UPPER FLOW LARGELY ANTICYCLONIC WITH PRONOUNCED SURFACE/850 RIDGING.
A WEAK RIPPLE SCOOTS THROUGH THE NW FLOW BUT PROBABLY NO MORE THAN
MID/HIGH CLOUDS WITH THIS. 925 TEMPS MODERATE A BIT.
SATURDAY-
UPPER RIDGE BUILDS ACROSS THE AREA. 925 TEMPS SHOW EVEN NICER
WARMING. COLUMN LOOKS LARGELY DRY.
SUNDAY-
TIMING DIFFERENCES BETWEEN ECMWF AND GFS IN SATURDAY NIGHT THROUGH
SUNDAY NIGHT WITH RESPECT TO SURFACE LOW/TROUGH PASSAGE. AT THIS
POINT IT LOOKS LIKE A LIGHT QPF EVENT THAT APPEARS TO BE LARGELY OF
THE LIQUID VARIETY.
&&
.AVIATION...IFR CEILINGS/VISIBILITIES AND AREAS OF LIFR CEILINGS
EXPECTED AS SURFACE LOW MOVES ACROSS SOUTHEAST WISCONSIN THIS
MORNING. SOME MVFR CIGS IN THE FAR SOUTHEAST AS OCCLUDED FRONT
PUSHES IN SOME SLIGHTLY DRIER AIR. HOWEVER UPPER LOW/TROF WILL
CONTINUE TO BRING A CHANCE OF SHOWERS. RATHER COMPLEX SITUATION
WITH NEXT UPPER LOW DROPPING IN FROM THE NORTHWEST TONIGHT.
IFR/LIFR CEILINGS AND MVFR/IFR VISIBILITIES WILL PREVAIL THROUGH THE
NIGHT...WITH POCKETS OF MVFR CONDITIONS. WHILE UPPER LEVELS
COOL...BOUNDARY LAYER WILL REMAIN RATHER WARM...SO CHANGEOVER TO A
RAIN/SNOW MIX WILL OCCUR SLOWLY LATER TONIGHT.
&&
.MARINE...
WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA WITH THE PASSING LOW PRESSURE SYSTEM ACROSS CENTRAL LAKE
MICHIGAN THIS MORNING. BRISK NORTHWEST WINDS AND HIGHER WAVES ARE
POSSIBLE THURSDAY AND THURSDAY NIGHT...AS THE SURFACE PRESSURE
GRADIENT TIGHTENS AND COLD AIR ADVECTION BEGINS. HOWEVER THIS WILL
BE LIMITED INITIALLY AS SECOND UPPER LOW DROPS IN FROM THE
NORTHWEST...RESULTING IN LINGERING TROUGH OVER LAKE MICHIGAN AREA.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...COLLAR
AVIATION/MARINE...HENTZ
