000
FXUS63 KMKX 180901
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
401 AM CDT THU MAR 18 2010
.SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH
WI WILL BECOME WEDGED BETWEEN SFC HIGH PRESSURE SPREADING ACROSS THE
SOUTHEAST CONUS AND SFC LOW PRESSURE TRACKING ACROSS THE SOUTHERN
CANADIAN BORDER TODAY AND TONIGHT. THE STRONGER PRESSURE GRADIENT
WILL CAUSE WINDS TO INCREASE OUT OF THE WEST. MODEL SNDGS SHOW DRY
ADIABATIC MIXING UP TO AROUND 875MB THIS AFTERNOON. WINDS AT THE TOP
AND MIDDLE OF THE MIXED LAYER WILL BE AROUND 20 TO 23KT...SO WINDS
MIXED DOWN TO THE SFC SHOULD MAX OUT AROUND 17KT WITH GUSTS UP TO
25KT. WEST TO SW WINDS AND 925MB TEMPS AROUND 11C AND 850MB TEMPS
AROUND 6C WILL ALLOW FOR TEMPS TO WARM INTO THE MID TO UPPER 60S
TODAY. NO LAKE BREEZE WITH THE STRONG WESTERLY WINDS. OVERHEAD
CIRRUS SHOULD NOT INHIBIT TEMPS FROM WARMING UP.
WITH THE DEEP MIXING...LOW DEWPOINTS WILL BE A CONCERN ONCE AGAIN
THIS AFTERNOON. MIN RH EXPECTED IN THE LOW TO MID 20S ACROSS MUCH OF
THE CWA. THEY WILL BE A LITTLE HIGHER TOWARD CENTRAL WI...CLOSER TO
THE CANADIAN LOW. FIRE WX VARIABLES NOT EXPECTED TO REACH DANGEROUS
LEVELS...BUT WILL BE AT AN ELEVATED CONCERN.
FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH
UPPER LOW PRESSURE TROUGH SWINGING ACROSS SOUTHERN CANADA
AND THE UPPER MIDWEST...AIDED BY RIGHT ENTRANCE REGION OF POLAR JET.
MEANWHILE...WESTERN PORTION OF POLAR JET DIVING SOUTH AND MEETING UP
WITH ZONAL SUBTROPICAL JET PRODUCING POTENT SHORTWAVE OVER 4 CORNERS
REGION BY FRI AFTERNOON.
ELONGATED BAROCLINIC ZONE OVER THE MIDWEST STRETCHING FROM KS TO WI
WILL SET UP BY FRI AFTERNOON AND SLOWLY SINK SOUTHWARD FRI NIGHT
INTO SAT. STRONG FGEN REGION WITH FAVORABLE OMEGA AND UPPER
DIVERGENCE WITH THE RIGHT ENTRANCE REGION OF POLAR JET WILL REMAIN
OVER SOUTHERN WI FROM FRI AFTERNOON THROUGH SAT MORNING. GOOD MODEL
AGREEMENT UP TO THIS POINT.
850MB AND 925MB TEMPS COLLAPSE PRETTY QUICKLY BEHIND THE FRONT FRI
NIGHT. THIS AREA WILL BE CO LOCATED WITH THE HIGHEST PRECIP AMTS.
MODEL SNDGS SHOW A SMOOTH COOLING FROM THE TOP DOWN...SO PRECIP WILL
TRANSITION FROM RAIN TO SNOW OVER THE WESTERN CWA IN THE
EVENING...AND IN THE EASTERN CWA AFTER MIDNIGHT. 1 TO 3 INCHES COULD
FALL IN THE SOUTHWEST WHERE THE TEMPS WILL BE COOLING QUICKLY AND
HIGHEST QPF EXPECTED. WARM GROUND WILL CAUSE MUCH OF THE SNOW TO
MELT QUICKLY...SO WENT CONSERVATIVE ON ACCUMULATIONS.
.LONG TERM...
SATURDAY THROUGH SUNDAY...FORECAST CONFIDENCE...MEDIUM
THE GFS AND NAM SLOW THE PROGRESSION OF THE FRONT ACROSS SE WI ON
SAT...WHILE THE ECMWF MOVES IT STRAIGHT THROUGH. IF THE SLOWER
PROGRESSION PANS OUT...MODEL SNDGS SHOW PRECIP FALLING AS
SNOW...EVEN THOUGH SFC TEMPS SHOULD WARM INTO THE UPPER 30S GIVEN
THE WARM MARCH SUN THROUGH THE CLOUDS. THIS WILL CAUSE SNOW TO MELT
ON CONTACT...ESPECIALLY IN AREAS OF LIGHTER SNOW FALLING. CONTINUED
TO BE CONSERVATIVE ON SNOW ACCUMULATIONS.
THE ECMWF SOLN MAINTAINS A MORE SOUTHERLY TRACK OF THE LOW CROSSING
THE SOUTHERN CONUS...WHILE THE GFS IS FURTHER NORTH. THE SOUTHERLY
SOLN WILL KEEP WRAP-AROUND PRECIP IN ASSOCIATED SFC LOW FROM
MAKING IT INTO SE WI. THERE IS STILL UNCERTAINTY...BUT ECMWF HAS
BEEN PRETTY CONSISTENT WITH FAVORING A MORE SOUTHERLY SOLN. BACKED
OF ON POPS/QPF EVEN MORE FOR SAT NIGHT AND SUN.
TOTAL QPF EXPECTED IS MUCH LESS THAN PREVIOUS FORECASTS...AROUND A
QUARTER TO A HALF INCH. LESS RIVER FLOODING CONCERNS NOW. TOTAL SNOW
ACCUM LIKELY TO BE 1 TO 3 INCHES ACROSS THE CWA...LESS NORTHEAST AND
MORE SOUTHWEST.
MONDAY...FORECAST CONFIDENCE...HIGH
HIGH PRESSURE WILL MAKE ITS WAY INTO THE GREAT LAKES REGION BY MON.
SKIES EXPECTED TO CLEAR QUICKLY BEHIND THE LOW PRESSURE SYSTEM. FCST
TEMPS ARE PROBABLY ON THE LOW SIDE. 850MB TEMPS REBOUND RATHER
QUICKLY. WILL NEED TO REASSESS IN THE NEXT FCST PACKAGE.
&&
.AVIATION...VFR CONDITIONS EXPECTED THROUGH THURSDAY. SOUTHWEST
WINDS WILL INCREASE TO 15 TO 25 KNOTS AS GRADIENT TIGHTENS UP WITH
LOW PRESSURE TROUGH OVER THE NORTHERN GREAT LAKES AND RIDGE TO THE
SOUTH.
&&
.MARINE...THE COOLER NEARSHORE WATERS OF LAKE MICHIGAN...WITH
SURFACE TEMPERATURES IN THE UPPER 30S...SHOULD SUPPORT AN INVERSION
OVER THE WATER TODAY. THIS WILL SUPPRESS ANY 22 TO 25 KNOT GUSTS
TRYING TO MIX DOWN TO THE SURFACE...PRECLUDING THE NEED FOR A SMALL
CRAFT ADVISORY TODAY.
SMALL CRAFT ADVISORY LEVEL WINDS AND WAVES ARE EXPECTED AT TIMES
FRIDAY NIGHT THROUGH SUNDAY...AS TWO SEPARATE LOW PRESSURE SYSTEMS
MOVE THROUGH THE REGION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...13/MRC
AVIATION/MARINE...05/DAVIS
