Issued by NWS Milwaukee/Sullivan, WI
000
FXUS63 KMKX 090835
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
335 AM CDT SAT MAY 9 2009
FORECAST FOCUS ON RAIN AND BRISK WINDS TODAY...QUIET STRETCH INTO
EARLY NEXT WEEK.
LATEST WATER VAPOR IMAGERY AND RUC ANALYSIS INDICATED A POTENT
SHORTWAVE TROUGH AND VORTICITY MAXIMUM CENTERED OVER SOUTHERN
WISCONSIN. ANOTHER SHORTWAVE TROUGH WAS LOCATED TO THE NORTHWEST
OVER FAR NORTHERN NORTH DAKOTA.
AT THE SURFACE...DEEPENING SURFACE LOW WAS CENTERED NEARLY UNDER
THE CENTER OF THE SHORTWAVE TROUGH...OVER SOUTHERN JEFFERSON
COUNTY. A LARGE AREA OF RAIN SHOWERS AND ISOLATED THUNDERSTORMS
WERE FOUND ROTATING AROUND THESE FEATURES.
.TODAY...LOCAL HIGH RESOLUTION MODELS SHOW THE RAIN PIVOTING
AROUND THE DEEPENING SURFACE LOW AS IT MOVES EAST INTO LOWER
MICHIGAN THIS MORNING. ON THIS TRACK...THE RAIN SHOULD AFFECT THE
NORTHERN COUNTIES THE MOST THIS MORNING...BEFORE TAPERING OFF TO
SCATTERED SHOWERS LATER THIS MORNING. THE SOUTHERN COUNTIES SHOULD
SEE MORE BREAKS BETWEEN THE SHOWERS THIS MORNING. THE RAIN SHOULD
MOVE OUT OF THE AREA BY THE EARLY AFTERNOON...SO REMOVED ALL POPS
THIS AFTERNOON.
OTHER ISSUE MAINLY THIS MORNING ARE THE BRISK WINDS. DEEPENING
SURFACE LOW CREATING A TIGHT PRESSURE GRADIENT ACROSS THE
AREA...ALLOWING WINDS TO BECOME GUSTY. AS THE LOW MOVES INTO LOWER
MICHIGAN THIS MORNING...WINDS WILL BECOME NORTHWEST AND REMAIN
GUSTY. COULD SEE GUSTS TO 35 KNOTS AT TIMES THIS MORNING...AS
THESE WINDS ARE MIXING DOWN FROM ONLY ABOUT 1000 FEET ABOVE THE
SURFACE PER AREA FORECAST SOUNDINGS.
AS THE LOW MOVES FURTHER EAST THIS AFTERNOON...THE PRESSURE
GRADIENT WILL WEAKEN...AND ALLOW FOR THE NORTHWEST WINDS TO
GRADUALLY SUBSIDE. COLD AIR ADVECTION IN THE WAKE OF THE LOW WILL
HELP MIX OUT SOME OF THE CLOUDS THIS AFTERNOON...AND WILL BRING
MUCH COOLER TEMPERATURES TO THE AREA. EXPECT HIGHS TO BE ONLY IN
THE 50S TODAY.
.TONIGHT THROUGH TUESDAY...NORTHWEST UPPER LEVEL FLOW WILL TAKE
OVER THE REGION DURING THIS TIME. HIGH PRESSURE WILL MOVE
SOUTHEAST ACROSS THE REGION AS WELL...WHICH WILL BRING QUIET
WEATHER TO SOUTHERN WISCONSIN. NORTH DAKOTA SHORTWAVE/VORTICITY
MAXIMUM WILL MOVE SOUTHEAST ACROSS THE AREA MAINLY SUNDAY MORNING
AND EARLY SUNDAY AFTERNOON...WITH ANOTHER WEAKER VORTICITY MAXIMUM
LATER ON MONDAY.
FORECAST SOUNDINGS OVERESTIMATING THE DEW POINTS BOTH DAYS...WHICH
WILL RESULT IN LESS INSTABILITY THAN THE MODELS ARE SHOWING.
THUS...WILL KEEP SUNDAY AND MONDAY DRY FOR NOW. LIGHT WINDS AND
CLEAR SKIES SUNDAY NIGHT WILL BRING LOWS INTO THE MID 30S TO LOW
LYING AREAS AND THE FAR NORTHERN COUNTIES. SO...KEPT THE PATCHY
FROST WORDING IN THESE AREA. A GRADUAL WARMING TREND IS EXPECTED
BY EARLY NEXT WEEK...AS THE HIGH MOVES SOUTHEAST AND BRINGS SOUTH
WINDS INTO THE AREA.
.TUESDAY NIGHT THROUGH FRIDAY...GFS AND ECMWF STILL IN FAIR
AGREEMENT WITH MOVING A STRONG COLD FRONT THROUGH THE REGION ON
WEDNESDAY. WARM ADVECTION TUESDAY NIGHT WITH SOME ELEVATED
INSTABILITY WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS.
CHANCES CONTINUE WEDNESDAY INTO WEDNESDAY NIGHT...AS THE FRONT
MOVES THROUGH THE REGION. FORECAST SOUNDINGS DO NOT SHOW MUCH
SURFACE BASED INSTABILITY BEFORE AND DURING THE FRONTAL PASSAGE.
DEEP LAYER WIND SHEAR IS QUITE STRONG. IF MORE INSTABILITY CAN BE
REALIZED...STRONG STORMS ARE POSSIBLE. MILDER TEMPERATURES SHOULD
BE FOUND WITH THE WARM AIR ADVECTION PATTERN AHEAD OF THE FRONT.
MORE UNCERTAINTY EXISTS FOR THURSDAY AND FRIDAY...SO WILL LEAVE
THESE PERIODS AS IS FOR NOW.
&&
.AVIATION...SCATTERED IFR AND LOWER CIGS/VSBYS EARLY THIS MORNING
SHOULD GRADUALLY INCREASE TO MVFR AND VFR AS DRIER AIR WORKS IN
FROM THE NORTHWEST LATER TODAY. HOWEVER MID LEVEL CLOUDS LIKELY TO
STICK AROUND WITH WEAK FORCING TONIGHT. VARIABLE WINDS RAPIDLY
INCREASING TO 15 TO 30 KNOTS WITH GUSTS TO 35 KTS FOR A TIME THIS
MORNING.
&&
.MARINE...COMPLEX SITUATION TO RESOLVE OVER THE NEARSHORE WATERS
THIS MORNING. DEEPENING LOW PRESSURE WILL MOVE RAPIDLY EASTWARD
OVER LAKE MICHIGAN THIS MORNING WITH RAPIDLY TIGHTENING PRESSURE
GRADIENT OVER NEARSHORE WATERS. WEST WINDS SOUTH OF NORTH POINT
LIGHT WILL TURN TO THE NORTH AS THE LOW MOVES TO THE EAST. GUSTS
WL LIKELY REACH GALE WARNING LEVELS FOR AN HOUR OR TWO BUT NOT
THINKING STRONG GUSTS WILL LAST LONG ENOUGH TO WARRANT UPGRADING
TO GALE WARNING AT THIS POINT...BUT WILL BE WATCHING CLOSELY.
WINDS WILL RAPIDLY SUBSIDE LATE THIS MORNING AND AFTERNOON SO WL
TRIM SMALL CRAFT ADVISORY EXPIRATION TO 21Z.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR
LMZ643>646.
&&
$$
SHORT/LONG TERM...08/WOOD
AVIATION/MARINE...11/MBK
