FXUS63 KGRR 301154
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
645 AM EST MON NOV 30 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(404 AM EST MON NOV 30 2009)
THE FIRST HALF OF THE WEEK LOOKS FAIRLY QUIET. A BRIEF PERIOD OF
LIGHT SNOW IS POSSIBLE MAINLY NORTH OF I-96 TONIGHT BUT ANY
ACCUMULATIONS WILL BE LESS THAN AN INCH. THE LATTER HALF OF THE WEEK
WILL BE COLDER WITH LAKE EFFECT SNOW SHOWERS POSSIBLE. THERE IS ALSO
THE POTENTIAL FOR ACCUMULATING SNOW THURSDAY OVER SOUTH CENTRAL
LOWER MICHIGAN AROUND THE JACKSON AREA...BUT IT/S STILL TOO EARLY TO
PINPOINT WHERE A STORM MOVING NORTHEAST FROM THE GULF OF MEXICO WILL
TRACK.
&&
.SHORT TERM...(404 AM EST MON NOV 30 2009)
(TODAY THROUGH WEDNESDAY)
FORECAST CONCERNS DEAL WITH PCPN TRENDS TODAY AND THE POTENTIAL FOR
ACCUMULATING SNOW LATE WEDNESDAY.
KGRR-88D SHOWS DIMINISHING RETURNS BUT THERE ARE STILL SCT
SPRINKLES/FLURRIES. IR LOOP SHOWS CLOUDS TRYING TO BREAK UP AS THEY
SINK SOUTH ACROSS THE LOWER PENINSULA. THAT/S NOT UNEXPECTED WITH
THE NORTH WINDS WE HAD OVERNIGHT. BUT NOW WINDS ARE BACKING TO THE
WEST AND I/D EXPECT CLOUDS TO INCREASE AGAIN WITH A FETCH OFF THE
LAKE. THUS WE SHOULD SEE CONSIDERABLE CLOUDINESS TODAY...ALONG WITH
A FEW BREAKS IN THE CLOUDS.
CHANCES FOR RAIN AND SNOW WILL INCREASE TONIGHT BRIEFLY AS
ISENTROPIC LIFT INCREASES IN THE WARM AIR ADVECTION PATTERN. IT
LOOKS LIKE ANY PCPN THAT DEVELOPS WILL BE RATHER QUICK HITTING WITH
DURATIONS AROUND 6 HRS. COULD SEE AN INCH POSSIBLE IN THE NORTH
CENTRAL CWA WHERE TEMPS WILL BE A TAD COLDER. LOOK FOR MIXED
RAIN/SNOW SOUTH OF M-46.
ATTENTION THEN TURNS TO THE CUTOFF LOW CURRENTLY SPINNING OVER FAR
NW MEXICO. THIS LOW IS PROGD TO DRIFT EAST ACROSS NRN MEXICO AND FAR
WEST TEXAS BEFORE BEING KICKED NORTH BY A STRONG SHORT WAVE IN THE
GULF OF ALASKA THAT WILL BE HEADED FOR THE NRN US. MODELS ARE STILL
NOT DECIDED ON THE TRACK OF THE STORM NORTHEAST FROM THE GULF OF
MEXICO. BUT THE NAM HAS TRENDED FARTHER NW AND TAKES THE LOW FROM
LOUISIANA NNE TO WRN KY BY 00Z THURSDAY. MEANWHILE THE
ECMWF/GFS/GEM/UKMET ARE ALL FARTHER NORTHEAST. BUT EVEN THEY HAVE
TRENDED A BIT FARTHER NORTHWEST. THEREFORE PCPN CHANCES ARE
INCREASING ESPECIALLY OVER THE SE CWA LATE WEDNESDAY. RIGHT NOW THIS
LOOKS LIKE A RAIN/SNOW MIX BUT A TRACK FARTHER NW WOULD MEAN MORE
RAIN.
&&
.LONG TERM...(404 AM EST MON NOV 30 2009)
(WEDNESDAY NIGHT THROUGH SUNDAY)
THE MAIN CHALLENGE IN THE LONG TERM DEAL WITH THE POTENTIAL FOR THE
STORM THAT IS TO LIFT OUT OF THE GULF...TO PRODUCE SOME SNOW HERE IN
SOUTHWEST LOWER MI.
THE LATEST TRENDS OF ALL MODELS IS TO TRACK THIS LOW FURTHER WEST.
THIS RAISES THE RISK FOR ACCUMULATIONS HERE IN SOUTHWEST LOWER MI.
RIGHT NOW THE JXN AREA STANDS THE BEST CHANCE TO SEE SNOW FROM THIS
POTENTIAL STORM NEARLY ALL MODELS DO SHOW THE BEST UPPER LIFT
STAYING WELL EAST OF JXN. IF THIS HOLDS TRUE...ANY ACCUMULATIONS
WOULD BE MINIMAL FOR SOUTHWEST LOWER MI. I THINK IT IS TOO EARLY
TO GET SPECIFIC WITH THIS STORM AS THE MODELS TYPICALLY STRUGGLE
WITH THESE UPPER LOWS OVER MEXICO AND SW U.S. IN TERMS OF EXACTLY
WHEN THEY WILL LIFT OUT AND THEIR TRACK. CLEARLY IT IS A STORM TO
MONITOR CLOSELY. I DID RAISE POPS WED NIGHT IN THE LAN TO JXN AREA
AND ADJUSTED THE PRECIPITATION TYPE THERE TO SNOW. I WILL MENTION
THIS POTENTIAL STORM IN THE HAZARDOUS WEATHER OUTLOOK.
THE LAKE EFFECT THAT DEVELOPS BEHIND THE STORM WILL LIKELY LEAD TO
ACCUMULATIONS IN THE THU TO FRI TIMEFRAME. WILL MAINTAIN THE HIGH
POPS AND HIGHLIGHT THE POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK.
JUST SOME ADJUSTMENTS TO TEMPERATURES THU INTO FRI GIVEN THE MORE
NORTHERLY FLOW AS A RESULT OF THE CLOSER APPROACH OF THIS STORM.
AREAS AROUND CLARE COUNTY SHOULD SEE RATHER COLD TEMPS THU NIGHT AND
FRI NIGHT.
&&
.AVIATION...(645 AM EST MON NOV 30 2009)
A COUPLE OF CONCERNS WITH THE AVIATION FORECAST.
WINDS DURING THE EVENING WILL BE ON THE INCREASE...ESPECIALLY FOR
KMKG. WE COULD SEE GUSTS OVER 25 KNOTS AFTER 00Z. ANOTHER CONCERN
IS A BAND OF PRECIPITATION THAT MAY MOVE INTO THE KGRR TO KMKG
LOCATIONS THIS EVENING. TRENDS ARE SOMEWHAT WARMER...SO I FEATURE
RAIN. CURRENTLY IT APPEARS THAT THE PRECIPITATION WILL BE
LIGHT...THUS I DID NOT REDUCE THE VISIBILITIES.
THERE IS A LOW RISK FOR MVFR OR LOWER CONDITIONS LATER TONIGHT AS
THE AIRMASS TRIES TO MOISTEN UP. CURRENTLY CONDITIONS ARE PRIMARILY
VFR UPSTREAM...AND I WILL KEEP THE FORECAST THAT WAY.
&&
.MARINE...(404 AM EST MON NOV 30 2009)
WE/LL CONTINUE THE SCA. OBS NEAR THE LAKESHORE CONTINUE TO SHOW
WINDS GUSTING OVER 20KTS. GIVEN THE COLD AIR ADVECTION
ONGOING...WAVES ARE LIKELY AOA 3 FT. WINDS MAY INCREASE TONIGHT
AFTER THEY BACK SOUTHWEST AS WARM AIR ADVECTION STRENGTHENS. THAT
WILL KEEP WAVES AOA 3 FEET.
&&
.HYDROLOGY...(404 AM EST MON NOV 30 2009)
NO HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY THROUGH TUESDAY AFTERNOON FROM ST JOSEPH
TO MANISTEE.
&&
$$
SYNOPSIS: 93
SHORT TERM: 93
LONG TERM: MJS
AVIATION: MJS
MARINE: 93
HYDROLOGY: 93
