FXUS63 KDLH 281845
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1245 PM CST SAT NOV 28 2009
.AVIATION.../18Z TAF ISSUANCE/
LOW CLOUDS AND SCATTERED SNOW SHOWERS ARE EXPECTED TO DEVELOP
ACROSS THE NORTHLAND TONIGHT AND LINGER INTO TOMORROW. THE CLOUD
COVER AND LIGHT SNOW IS ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE
DIGGING SOUTHEAST OUT OF CANADA. CIG HEIGHTS WILL GENERALLY RANGE
FROM MVFR TO IFR TONIGHT AND SUNDAY MORNING...WHILE VFR/HIGH MVFR
VSBYS WILL BE ASSOCIATED WITH THE AREAS OF LIGHT SNOW.
&&
.PREV DISCUSSION... /ISSUED 1152 AM CST SAT NOV 28 2009/
UPDATE...
MADE MINOR ADJUSTMENTS TO LOWER WINDS AND TO DE-EMPHASIZE
PRECIPITATION TONIGHT. RAISED TEMPERATURES A LITTLE TODAY.
DISCUSSION...
WITH A BROAD...DEEP...AND UNSEASONABLY MILD PACIFIC AIR MASS...THE
STORM TRACK REMAINS NORTH OF OUR AREA DURING THE NEXT FOUR DAYS.
ANY PRECIPITATION IS DOUBTFUL WITH A SERIES OF MINOR DISTURBANCES
EXTENDING SOUTHWARD INTO OUR AREA...BOTH SURFACE AND ALOFT...
ASSOCIATED WITH EACH STORM MOVING THROUGH SOUTHERN CANADA. VORTMAX
AND ACTUAL UPWARD VELOCITY/FRONTOGENESIS VALUES REMAIN WELL TO OUR
NORTH...PRECIPITATION TENDS TO TRACK TO THE LEFT OF VORTMAX PATHS.
WE WILL MAINTAIN CONTINUITY WITH LEAVING IN SMALL CHANCES OF VERY
LIGHT PRECIPITATION FOR NEARLY EVERY PERIOD. EPISODES OF WARM
ADVECTION WILL REMAIN LONGER AND STRONGER THAN ANY COLD ADVECTION.
PREV DISCUSSION... /ISSUED 604 AM CST SAT NOV 28 2009/
AVIATION...
VFR CONDITIONS WILL PREVAIL TODAY. THE EXCEPTION WILL BE IN THE
KHYR TO KPBH AREA WHERE A BATCH OF LOW CLOUDS AROUND 1-2 KFT HAS
DEVELOPED THAT WILL GRADUALLY DISSIPATE AFTER 16Z. CEILINGS WILL
FALL TO AROUND 7-9 KFT LATE IN THE DAY. LOW CLOUDS WITH BASES
AROUND 2-3 KT AND SCT -SHSN WILL SPREAD SE OVER FA GENERALLY AFTER
04Z. THE LIGHT -SN WILL REDUCE VSBY TO MVFR/ISOLD IFR AT TIMES
THROUGH SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 307 AM CST SAT NOV 28 2009/
DISCUSSION...
THRU SUN...
WEAK SFC TROF WILL PASS THRU OUR CWA TDA WHICH WILL SWITCH OUR
WINDS ARND TO THE NW AND SET UP A CAA PATTERN FOR THE WEEKEND.
SFC TROF IS FOLLOWED QUICKLY BY SEVERAL UPR LVL S/WVS WHICH MERGE
INTO A FAIRLY SUBSTANTIAL TROF OVR THE WRN GRT LKS ON SUN. MSTR IS
GREATLY LACKING...SO POPS WERE KEPT IN SLGT OR LOW CHC CATEGORY
AND QPF RATHER LOW AS WELL. SOME LAKE ENHANCED SNOW SHOWERS ALG S
SHORE PSBL ON SUN AS NW WINDS PICK UP...BUT DIREC NOT JUST THE
BEST FOR OUR COUNTIES AND DELTA-T MARGINAL AT BEST. PUT IN HIGH
CHC POPS ALG S SHORE...BUT DON'T EXPECT A LOT OF ACCUMULATION.
SHUD SEE A 5-10 DEG DROP IN HIGH TEMPS FROM SAT TO SUN IN STRONG
CAA. DO NOT EXPECT BOTTOM TO DROP OUT SAT NITE HWVR DUE TO HEAVY
CLD CVR.
MON THRU THU...
MID LVL RIDGING WILL BRING A SERIES OF FAST MOVING WAVE ACROSS THE
NORTHLAND THROUGH THE WEEK. AN ELONGATED VORT WILL NOSE INTO THE
IRON RANGE/ARROWHEAD REGION MON BRINGING A CHC FOR LIGHT SN ACCUM.
AS THE WAVE EXITS LK EFFECT SNOW SHOWERS MAY LINGER ALONG THE SOUTH
SHORE INTO MON NIGHT. MAIN FOCUS IN LONG TERM IS ON A STRONG SHORT
WAVE THAT DIGS SOUTH OUT OF WRN CANADIAN PROVIDENCES AND INTO THE
UPR MIDWEST IN THE TUES/WED TIME FRAME BRINGING A CHC FOR SNOW AND A
COOL DOWN TO MORE SEASONABLE TEMPERATURES BY MID WEEK. FCST
DIFFICULTY IN TIMING THE FAST MOVING WAVE WITH A 70-80KT MID LVL JET
AND 40-50 KT TRAILING LLJ. THE 00Z RUNS OF GFS/EC ARE TRENDING
FASTER WITH THIS FEATURE SO ADJUSTED WIND SHIFT AND TEMPS
ACCORDINGLY. USED A BLEND OF EC/GFS FOR TIMING IN GRIDS. TRENDED
TEMPS DOWN BEHIND THE FROPA AS THE EXITING TROUGH ALLOWS FOR A SURGE
OF MUCH COOLER AIR INTO THE REGION. LONG TERM MDLS IN GOOD AGREEMENT
THAT 500 MB TEMPS PLUMMET INTO THE NEGATIVE 30-35 C RANGE WITH
CORRESPONDING RAPID 1000-500 MB THICKNESS FALLS OF AROUND 25 DAM
BTWN 12Z TUES AND 12Z WED. INCREASING LAPSE RATES DUE TO 850 MB
TEMPS FALLING INTO THE TEENS WED...COMBINED WITH A 15-20KT W/NW BDRY
LYR FETCH AND LINGERING MOISTURE IS EXPECTED TO PRODUCE A FEW INCHES
OF ACCUMULATING LK EFFECT/ENHANCED SNOW ALONG THE SNOW BELT REGION
OF NRN WIS. INCREASED TO CHC POPS IN THIS AREA WED/WED NIGHT WITH
THE TIMING AND SPECIFIC WIND TRAJECTORY DETAILS TO STILL BE WORKED
OUT.
AVIATION...06Z TAF ISSUANCE...
BRISK WLY FLOW ALOFT IS MAINTAINING A STEADY PROGRESSION OF
MID/HIGH LEVEL CLOUDS ACROSS CWA. A WEAK SFC WAVE WILL PUSH ACROSS
THE REGION OVERNIGHT WITH LITTLE EFFECT AS MOISTURE CONVERGENCE IS
LIMITED. COND PRESS DEFICIT FCST FROM NAM12/RUC13 SUGGEST A BRIEF
PERIOD OF MVFR CEILINGS MAY OCCUR NEAR KBRD AFTER 10Z SATURDAY.
CONFIDENCE NOT HIGH AT THIS POINT GIVEN LACK OF ANY DEVELOPMENT AT
THIS HOUR UPSTREAM.
&&
.POINT TEMPS/POPS...
DLH 41 26 34 23 / 10 40 10 10
INL 33 22 28 17 / 10 40 20 10
BRD 41 26 35 22 / 10 30 10 10
HYR 43 28 34 20 / 10 20 10 10
ASX 42 28 34 22 / 10 50 40 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
BERDES/BERDES/BERDES
