000
FXUS63 KMKX 200902
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
302 AM CST THU NOV 20 2008
.SHORT TERM...
TODAY-
UPPER TROUGH MOVES ACROSS THIS AFTERNOON...WITH 850 MB TEMPS OF
-16C. ADIABATIC LAPSE RATES BENEATH SHOULD RESULT IN
FLURRIES...THOUGH GUIDANCE HAS BACKED OFF A LITTLE ON EXTENT OF
CONVECTIVE SNOW SHOWERS. SOMEWHAT DRIER IN DENDRITE LAYER THAN
EARLIER RUNS...AND CURIOUS CLEARING AREA ALONG LAKE MICHIGAN PER
SATELLITE IMAGERY SEEMS TO CONCUR.
CONSENSUS 925 MB TEMPS SUGGEST ONLY UPPER 20S FOR HIGHS TODAY.
TRAJECTORY FORECASTS ALSO SHOW SOURCE FROM NORTHWEST
ONTARIO...WHERE HIGHS WERE IN THE MID TO UPPER 20S YESTERDAY.
CURRENT READINGS ARE AROUND 30...SO EXPECT A COUPLE MORE DEGREES
COOLING AND THEN NOT MUCH OF A RISE TODAY IN FACE OF STRONG COLD
ADVECTION AND PLENTY OF CLOUDS/FLURRIES.
TONIGHT-
SHOULD CLEAR OUT LATER IN THE EVENING AND GET QUITE COLD. GRADIENT
SHOULD REMAIN UP AND KEEP STRONG INVERSION FROM FORMING. BUT WITH
-13 C AT 925 MB AND -15 C AT 850 MB...LOWER TEENS A GOOD BET AWAY
FROM LAKE MICHIGAN AND EVEN SOME SINGLE DIGITS IN A FEW OF THE
WESTERN VALLEYS THAT CAN DECOUPLE BETTER.
FRIDAY-
150 METER 500 MB HEIGHT RISES ADVERTISED AS DEEP UPPER TROUGH
SLIDES EAST. SURFACE WINDS GO WESTERLY AS POLAR HIGH MOVES INTO
OHIO VALLEY. COLD START BUT A MILDER AFTERNOON WITH WARM ADVECTION
IN PROGRESS.
SATURDAY-
MODELS CONTINUE TO TAKE A WEAKENING SHORT WAVE TROUGH JUST SOUTH
OF THE AREA WITH LIMITED MOISTURE. THREAT FOR SNOW OFF TO THE WEST
GRADUALLY DRIES UP AS IT HEADS EAST-SOUTHEAST. CERTAINLY A PESKY
FLY IN THE OINTMENT BUT GFSENSEMBLES ARE DRY SO WILL STAY THE DRY
ROUTE FOR NOW.
.LONG TERM...
SUNDAY AND MONDAY-
ANOTHER DEEP CLOSED LOW DIGS IN FROM THE NORTHWEST...WITH CENTER
GOING OVERHEAD MONDAY. 00Z ECMWF SUGGESTS THAT WARM CONVEYOR BELT
SETS UP JUST EAST OF US. WILL KEEP SLIGHT CHANCE OF RAIN OR SNOW
SHOWERS SUNDAY.
LOOKS LIKE UNSETTLED AND COLD ON MONDAY WITH POSSIBILITY OF SNOW
SHOWERS UNDER UPPER SYSTEM. AS ALWAYS WILL HAVE TO KEEP AN EYE ON
EVOLUTION OF THIS SYSTEM BUT PRESENT INDICATIONS ARE THAT ANY
SIGNIFICANT ACCUMULATING SNOW WILL BE WELL TO THE EAST.
&&
.AVIATION...
SMALL AREA OF CLEAR SKIES OVER FAR ERN WI SHOULD BECOME
CLDY AGAIN THIS AM GIVEN LARGE AND SURROUNDING STRATUS DECK OVER THE
WRN GRTLKS AND STATES WEST OF WI. LARGE AREA OF STRATUS...MAINLY
VFR...IS IN WAKE OF STRONG COLD FRONT AND CURRENT CYCLONIC FLOW.
WEST TO EAST UPPER TROUGH AXIS FROM ND TO MN WILL SHIFT SWD TODAY
AND CONTRIBUTE TO SUSTAINED SC FIELD AND SOME MINOR LOW LEVEL
INSTABILITY. CIGS WILL RANGE MAINLY VFR FROM 3.5-4.0 KFT WITH SCT
FLURRIES EXPECTED. UPPER TROUGH TO SHIFT SE OF SRN WI THIS EVENING
WITH SUBSIDENCE AND A VERY DRY AIRMASS LEADING TO CLEARING. HIGH
PRESSURE AND LIGHTER WINDS WILL THEN SHIFT INTO WI BY FRI AFT.
&&
.MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT UNTIL NOON ON FRI. A
TIGHT PRESSURE GRADIENT BTWN LOW PRESSURE MOVING EWD ACROSS THE ERN
GRTLKS AND A LARGE CANADIAN HIGH THAT WILL SHIFT INTO THE GREAT
PLAINS WILL CONTINUE TO GENERATE BRISK NW WINDS OVER THE UNSTABLE
LAKE WATERS THROUGH FRI AM. WAVES WILL REMAIN HIGH UNTIL LIGHTER
WINDS FROM THE APPROACHING POLAR HIGH RESULTS IN WAVES BELOW 4 FEET
FRI AFT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 12 PM CST FRIDAY FOR LMZ643>646.
&&
$$
SHORT/LONG TERM...CRAVEN/02
AVIATION/MARINE...GEHRING/20
