NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 272023
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
325 PM CDT WED AUG 27 2008

.DISCUSSION...FORECAST CENTERS ON INCREASING THREAT OF PRECIPITATION
LATER TONIGHT INTO THURSDAY EVENING.  MORNING ACTIVITY ACROSS MN/IA
DIMINISHED AS PLANNED AS IT PUSHED INTO LARGE AREA OF SUBSIDENCE AND
DRIER AIR OVER CENTRAL MS VALLEY.  MCV SHOWING UP IN SOUTHEAST IA
PER LATEST VSBL IMAGERY. PREFER GFS SOLUTION FOR THE SHORT TERM DUE
TO BETTER AGREEMENT IN SYNOPTIC SCALE FEATURES BETWEEN SUCCESSIVE
MODEL RUNS.  LOW LEVEL JET BEGINNING TO INCREASE ACROSS PLAINS AS
WINDS BEGINNING TO VEER AHEAD OF STRONG SHORT WAVE TROUGH IN MT/SRN
CANADA.  700H PROFILERS SHOWING VEERING WINDS IN THE HIGH PLAINS
INDICATING PRECURSOR SHORT WAVE THAT WILL AFFECT WI LATER TNGT AND
THU MRNG.  AHEAD OF THIS WAVE...NOSE OF WEAKER LLJ OF 20 TO 30KTS
PUSHES ACROSS SRN WI WITH A RAPID INCREASE IN PRECIPITABLE WATER OF
ONE HALF INCH.  ELEVATED LIFTED INDEX DROPS TO AROUND ZERO BY 12Z IN
THE WEST BUT MID LEVEL LAPSE RATES STILL ON THE WEAK SIDE.  THINKING
BETWEEN ACTIVITY TO THE WEST SPILLING SOUTHWARD ALONG THICKNESSES
AND LOW LEVEL MOISTURE FLUX CONVERGENCE...SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS ARE EXPECTED.

LINGERING CLOUD COVER WILL ACT TO RETARD HEATING SOMEWHAT IN THE
AFTERNOON AS BEST LOW LEVEL CONVERGENCE MOVES THROUGH...LIMITING
MORE ORGANIZED CONVECTION.  NEVER THE LESS...RIGHT ENTRANCE REGION
OF UPPER JET PASSES ACROSS REGION DURING THE AFTERNOON AND
EVENING...AND FN RESPONSE TO INCREASING LOW TO MID LEVEL 2D FULL
WIND FRONTOGENESIS WORTH NOTING.  HENCE WL GO WITH SCT REDEVELOPMENT
IN THE AFTN SOUTH CENTRAL INCREASING TO NUMEROUS ACTIVITY IN THE
SOUTHEAST DURING THE EVENING. SHORT RANGE ENSEMBLE POPS INCREASES TO
70 PERCENT DURING THE EVENING IN THE SOUTHEAST.

NORTHWEST BREEZES CARRY LESS HUMID AIR ACROSS AREA LATE THU NIGHT
AND FRI WITH LIGHT BOUNDARY LAYER WINDS SETTING UP FOR FRIDAY
NIGHT.  WEAK FRONTAL BOUNDARY TO THE NORTH WITH PATCHY MID LEVEL
CLOUDS BUT WITH LIGHT WINDS AND INCREASE IN LOW LEVEL MOISTURE FROM
RAIN...THINKING FOG A GOOD BET FOR EARLY SATURDAY.  PENDING CLOUD
COVER...MAY BE SOME QUARTER MILE VISIBILITIES.

MORE UNCERTAINTY CREEPING INTO THE EXTENDED FORECAST BEYOND MONDAY
NIGHT.  UNCERTAINTY MAINLY DUE TO TIMING AND TRACK OF GUSTAV AND ITS
AFFECT ON APPROACHING SHORT WAVE TROUGH FOR TUE AND WED.  LATEST
EXTENDED GUIDANCE TAKING A MORE NORTHEASTLY TRACK AND CARRYING
REMAINS OF HURRICANE INTO WESTERN GULF DURING THE PERIOD...WITH A
SECOND TROPICAL DISTURBANCE IN THE WRN ATLANTIC.  GFS TRENDING
SLOWER WITH WEAKENING SHORT WAVE TROUGH INTO THE UPPER MIDWEST
DURING THIS PERIOD...WHILE HI RES ECMWF MUCH WEAKER AND EVEN SLOWER
WITH SURFACE TROUGH...AS HIGH PRESSURE AND SUBSIDENCE REINFORCES
ITSELF ACROSS ERN CONUS.  LITTLE RUN TO RUN CONSISTENCY IN ANY
EXTENDED GUIDANCE AT THIS POINT. MOISTURE REMAINS LOW...HOWEVER LOW
LEVEL INCRG SRLY WNDS DOES RESULT IN A BIT OF ELEVATED INSTABILITY
TUE INTO WED. FOR NOW...WL GO WITH SCHC POPS MOST AREAS TUE INTO WED
NGT PERIOD.  IF CURRENT TRENDS CONTINUE...WL PROBABLY BE ABLE TO
PULL POPS OUT FROM AT LEAST TUE...AND POSSIBLY INTO WED.  GFS
ENSEMBLES SHOWING LOTS OF VARIABILITY IN THE LATER PERIODS...SO
LITTLE STOCK CAN BE PUT IN DGEX EITHER. HPC LEANING ON ECMWF MEAN
WHICH HAS BEST POPS IN LAST PERIODS.

GFS 500MB 5 DAY MEANS SHOW ZONAL FLOW WITH NEAR NORMAL HEIGHTS
ACROSS NRN CONUS TRANSITIONING TO INCREASING HEIGHTS OVER THE
GTLAKES DUE TO UPSTREAM TROFFING ACROSS WEST.  HENCE
WARMER...DAYTIME TEMPERATURES LIKELY...AND MORE SELY BREEZES SHOULD
RESULT IN SLIGHTLY WARMER READINGS ALONG LAKESHORE AS WELL.  DRY
PATTERN TO CONTINUE INTO EARLY SEPTEMBER...PENDING TRACK OF GUSTAV.

&&

.AVIATION...WEAK SURFACE RIDGING AND LIGHT WINDS IN PLACE...WHILE
SCATTERED CU THIS AFTERNOON GIVES WAY TO INCREASING MID TO HIGH
CLOUDS AHEAD OF LOW PRESSURE AREA TO THE NORTHWEST.  SMALL CHANCES
FOR THUNDERSTORMS LATE TONIGHT AND THURS MORNING FOR SOUTHWEST AND
SOUTH-CENTRAL WI..BUT OPTED TO LEAVE OUT OF TAFS FOR NOW.
INCREASING CLOUDS OVERNIGHT SHOULD HINDER ANY FOG DEVELOPMENT.

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

$$
SHORT TERM/LONG TERM....MBK
AVIATION................CJK