FXUS63 KDLH 291236
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
636 AM CST SUN NOV 29 2009
.AVIATION...
HIGHLY VARIABLE CEILINGS AND ISOLD -SHSN FOR THE FA THROUGH
16Z. TAF SITES WILL GENERALLY HAVE PREVAILING VFR CIGS
TODAY...WITH PERIODS OF MVFR/IFR CEILINGS AS A SHORT WAVE TRACKS
SE OVER THE FA. LOWEST CEILINGS THIS MORNING WILL BE FOUND OVER
NW AND NC MN...WITH A PERIOD OF IFR POSSIBLE AT KBRD AND KINL.
CEILINGS WILL GRADUALLY LIFT THROUGH THE EVENING BEFORE ANOTHER
FAST MOVING WAVE SPREADS LOW CLOUDS BACK OVER THE REGION DURING
THE DAY MONDAY.
&&
.PREV DISCUSSION... /ISSUED 312 AM CST SUN NOV 29 2009/
DISCUSSION...
THRU MON...
BROAD UPR LVL TROF PASSING OVR CWA TDA PRODUCING SOME -SN OR
FLURRIES ACRS SRN ZONES N OF FNTL BNDRY ACRS ERN IA/SRN WI. AMS IS
VRY DRY WITH NO SIG MSTR SOURCE...SO ANY ACCUMS WILL BE VERY LIGHT.
BRIEF WINDOW OF OPPORTUNITY ABOUT MIDDAY FOR SOME LES ALG S SHORE
WITH DELTA-T ARND 16...BUT WINDS DO NOT REMAIN FAVORABLE FOR VERY
LONG AND AMS IS QUITE DRY...SO ANY ACCUMS SHUD BE LIMITED TO AN INCH
OR TWO. SFC AND UPR LVL RIDGING INCREASES TNGT...BUT STRONG VORT MAX
SLIDES DOWN ACRS THE WRN GRT LKS IN NW FLOW ON MON. STRONG LIFT MAY
OVERCOME THE LACK OF MSTR TO THE POINT WHERE AN INCH OR SO OF
SNOWFALL MAY BE REALIZED...ESPECIALLY ACRS NERN HALF OF CWA...AND
THIS WILL BE REFLECTED IN THE NEW FCST.
TUE THRU FRI...
MAIN FOCUS IN LONG TERM IS ON A STRONG SHORT WAVE THAT DIGS SOUTH
OUT OF MANITOBA AND INTO THE UPR MIDWEST TUES/WED. THE WAVE AND SFC
LOW WILL BRING A CHC FOR SNOW AND A COOL DOWN TO MORE SEASONABLE
TEMPERATURES THROUGH MID WEEK AND INTO THE WEEKEND. FCST DIFFICULTY
IN TIMING THE FAST MOVING WAVE WITH A 70-80KT MID LVL JET AND 40-50
KT TRAILING LLJ. THE MDL RUNS ARE DEEPENING THE TROUGH FURTHER THAN
PREVIOUS RUNS...WITH THE GFS/NAM80 DEPICTING A CLOSED LOW THAT CLIPS
THE INTERNATIONAL BORDER THROUGH 12Z WED. PREVIOUS FCST ON TRACK
WITH ONLY MINOR ADJUSTMENTS TO INCREASE POPS IN NRN WIS ZONES FOR
INCREASING CONFIDENCE OF LK EFFECT/ENHANCED SNOW AS THE LOW DEPARTS.
LAPSE RATES INCREASE AS 850 MB TEMPS FALL INTO THE TEENS WED/THURS.
THE FAVORABLE DELTA-T VALUES COMBINED WITH A 15-20KT W/NW BDRY LYR
FETCH AND LINGERING MOISTURE AREA EXPECTED TO PRODUCE A FEW INCHES
OF ACCUMULATING LK EFFECT/ENHANCED SNOW ALONG THE SNOW BELT REGION
OF NRN WIS. ALTHOUGH SPECIFIC WIND TRAJECTORY DETAILS TO STILL BE
WORKED OUT...THE BEST THREAT FOR SN OCCURS IN THE WED NIGHT THROUGH
THURS NIGHT PERIOD WHEN GFS BUFR SOUNDING AT KIWD SUGGESTS A
SATURATED PROFILE WITH STEEP LAPSE RATES TO 700-750 MB AND 40-50
J/KG OF CAPE.
AVIATION...06Z TAFS...
RADAR INDICATES SOME LIGHT SNOW HAD OCCURED AT BRD AND SOME MAY
FALL AT HYR. ALOS MVFR TO IFR CIGS ARE MOVING SOUTHEAST THROUGH
FORCAST AREA. THIS TREND WILL CONTINUE THROUGH THE EARLY MORNING
HOURS. THE MVFR TO IFR CIGS WILL CONTINUE INTO THE DAYLIGHT HOURS
AND WILL IMPROVE TO VFR ACROSS ALL SITES EXCEPT WHERE MVFR CIGS
MAY LINGER UNTIL SUNSET. VSBYS AMY DROP DOWN INTO MVFR OVERNIGHT
IN THE AREAS OF LIGHT SNOW.
&&
.POINT TEMPS/POPS...
DLH 34 25 36 28 / 20 10 30 10
INL 31 19 32 24 / 20 10 20 10
BRD 34 23 37 26 / 10 10 20 10
HYR 34 21 37 21 / 20 10 20 10
ASX 34 24 36 25 / 30 10 30 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
04/GRANING
