000
FXUS63 KMKX 211926
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
226 PM CDT THU AUG 21 2008
FORECAST FOCUS ON TWO MAIN CHANCES OF PCPN...ONE TONIGHT WITH
NORTHWARD MOVING S/W IN MOIST SRLY FLOW...AND THE SECOND ON
SATURDAY WITH FROPA.
.TONIGHT...SHOWERS HAVE BEEN MAKING STEADY PROGRESS NORTH INTO THE
CWA TODAY...BUT STRUGGLING TO PRODUCE MUCH RAIN WITH DRY EASTERLY
FLOW WORKING AGAINST IT. RAIN IS ASSOC WITH WELL DEFINED H5 S/W
CIRCULATION THAT SLOWLY GETS ABSORBED INTO LARGER LONGWAVE TROF
TRACKING QUICKLY OUT OF THE PAC NORTHWEST. NOT ENCOURAGED BY THE
SCATTERED LOOKING NATURE OF THE REGIONAL RADAR RETURNS OF THE RAIN
AREA. HAVE A HARD TIME ACCEPTING THE LIKELY POPS FROM THE MOS
GUIDANCE AND WILL THEREFORE KEEP IT IN THE SCT/CHC CATEGORY
OVERNIGHT.
.FRIDAY...NOT MUCH IN THE WAY OF DEEP FORCING ON FRIDAY AS MAIN H5
S/W CIRCULATION NOW NORTH OF THE AREA. BUT THERE IS SOME LINGERING
SUBTLE H5 TROFINESS AND SFC DWPNTS SHOULD CLIMB INTO THE UPPER
60S...MAYBE LOW 70S. THESE DWPNTS ARE ALREADY IN SRN IL AND DON/T
HAVE FAR TO TRAVEL. SOUNDINGS SHOW SOME INSTABILITY AND CAN/T RULE
OUT SOME DIURNAL DEVELOPMENT. CONTINUED MOIST SRLY FLOW WILL
LINGER THE SMALL CHANCE THROUGH FRIDAY NIGHT.
.SATURDAY...FROPA IS EXPECTED DURING THE MORNING AND EARLY
AFTERNOON. THIS IS NOT A DIURNALLY FAVORABLE TIME.
ADDITIONALLY...THE MAIN UPPER SUPPORT IS LIFTING WELL TO THE NE...DEEP
INTO CANADA...FAR AWAY FROM SRN WI. AT THE SFC...THE FRONT BEGINS
TO GET PINCHED BY HIGH PRESSURE AND THIS IS NEVER A GOOD SITUATION
FOR NEEDED RAINFALL. GUIDANCE HAS PULLED BACK TO CHANCE VALUES AND
THIS IS CLEARLY THE WAY TO GO. UNFORTUNATELY...FOR THOSE LOOKING
FOR RAIN OVER THE NEXT COUPLE OF DAYS...IT IS NOT LOOKING LIKE
ANYTHING BENEFICIAL IS ON THE WAY.
AFTER FROPA...HIGH PRESSURE BEGINS TO BUILD IN FOR ANOTHER PERIOD
DRY WEATHER THAT SHOULD LAST FROM SUNDAY THROUGH ABOUT NEXT
THURSDAY.
&&
.AVIATION...PCPN SHIELD WILL LIFT THRU FCST AREA WITH SHORT WAVE IN
N NCTRL IL AT 18Z WITH MAINLY VFR CIGS/VSBYS THO SOME MVFR
CONDITIONS WITH SCT HEAVIER SHOWERS. INSTABILITY MINIMAL SO EXPECT
LITTLE IF ANY THUNDER AND HAVE LEFT OUT OF TAFS. INCREASING
SOUTHERLY WINDS IN THE LOW LEVELS WL BRING DEEPER LOW LEVEL MOISTURE
AND RETURN OF MVFR CIGS LATER TONIGHT WITH MORE LIGHT FOG...WITH
BOUNDARY LAYER MIXING LIMITING POTENTIAL FOR IFR CONDITIONS.
&&
.MARINE...SSE WINDS WILL APPROACH SMALL CRAFT ADVISORY LEVELS FRIDAY
AFTERNOON AND EARLY EVENING. WILL HOLD OFF ON HEADLINE FOR NOW AS
FCST SNDGS INDICATE FREQUENT GUSTS WILL BE AROUND 20 KTS...WITH
FETCH BUILDING 2 TO 4 FOOT WAVES.
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...05
AVIATION/MARINE...09
