FXUS63 KDLH 011801
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1201 PM CST TUE DEC 1 2009
.UPDATE...18Z TAF DISCUSSION...
&&
.AVIATION...IFR/LIFR CONDITIONS WILL BE FOUND IN SNOW AT KINL AS A STRONG
LOW PRESSURE SYSTEM PUSHES EAST THROUGH THE HEART OF THE
NORTHLAND. EXPECT KHIB TO DROP TO MVFR/IFR LATER IN THE AFTERNOON
ONCE THE LOWER LAYERS SATURATE AND BETTER LIFT APPROACHES. THE
SOUTHERN TERMINALS WILL REMAIN ON THE SOUTHERN END OF THE BETTER
FORCING...BUT MVFR JUST AHEAD OF AND BEHIND THE SURFACE LOW WILL
SPREAD MVFR CONDITIONS EASTWARD AFTER A PERIOD OF VFR IN THE
AFTERNOON...AFFECTING KHYR LATEST. EXPECT MVFR STRATUS AND GUSTY
WEST/NORTHWEST WINDS ON THE BACK SIDE OF THE LOW WITH STRONG
PRESSURE RISES LEADING TO ISALLOBARIC ACCELERATION. /DONOFRIO
&&
.PREV DISCUSSION... /ISSUED 1015 AM CST TUE DEC 1 2009/
UPDATE...MADE SOME ADJUSTMENTS TO POPS/WX TO LINE UP BETTER WITH
CURRENT TRENDS PER SATELLITE AND RADAR. MADE ROOM FOR MORE
SUNSHINE OVER THE SOUTHERN HALF OF THE FA WHERE THERE IS LESS
CLOUD COVER. WITH MORE SUN...ALSO RAISED MAX TEMPS OVER THE
SOUTHERN TIER OF THE FA. EXPECTED INCREASE IN ONSHORE WINDS ALONG
THE NORTH SHORE AND HAVE ISSUED A SCA. REST OF THE FORECAST IN
GOOD SHAPE. /GSF
PREV DISCUSSION... /ISSUED 345 AM CST TUE DEC 1 2009/
DISCUSSION...
THRU WED...
MODELS IN REASONABLY GOOD AGMT ON POSITION AND EVOLUTION OF SFC LOW
OVR NWRN ND ATTM. LOW WILL DIP DOWN ACRS CENT MN AS IT PROGRESSES
EWD...MOVG E OF LK SUP BY MIDDAY WED. SPEED OF SYSTEM AND LACK OF A
GOOD MSTR SOURCE WILL LIMIT ACCUMS...BUT STRENGTH OF ASSOC
DYNAMICS OUGHT TO BE SUFFICIENT FOR 3-5 INCHES N OF THE IRON
RANGE...WITH LOCAL AMTS PSBLY TO ARND 6 INCHES CLOSE TO THE CN
BORDER. AMTS WILL THEN TAPER OFF TO LESS THAN AN INCH IN SRN PARTS
OF THE CWA. WILL ISSUE WSW FOR N OF THE RANGE RUNNING FROM NOON TDA
TO NOON WED. FUTURE SHIFTS MAY BE ABLE TO CANCEL EARLY...BUT WITH UPR
LVL CYC FLOW ALOFT THRU THE PD...IT WILL PRBLY NOT STOP SNOWING
COMPLETELY. THE MAJOR ACCUMULATING SNOW HWVR WILL PRBLY FALL FROM
MID AFTN TDA THRU VERY EARLY WED MRNG. WINDS ON BACK SIDE OF THE LOW
WILL ALSO BE A FACTOR ON WED...CAUSING SOME BLOWING AND DRIFTING.
EXPECT LOWER HIGH TEMPS ON WED AS CAA BEGINS TO SET UP...CONTINUING
THRU THE REST OF THE WEEK. /04
WEDNESDAY NIGHT THRU SUNDAY...
MDT/STRONG MDL CONSENSUS THAT A LARGE AMPLITUDE MID LVL TROF WILL
DOMINATE THE REGIONAL WEATHER PATTERN THIS PERIOD. BY BEGINNING OF
PERIOD...SHOULD HAVE ESTABLISHED A SNOW PACK UPSTREAM OF CWA AND INTO
AT LEAST NRN THIRD OF AREA. 85H TEMPS WILL DROP BELOW NORMAL VALUES
FOR THE PERIOD SO SHOULD ACTUALLY SEE MIN/MAX TEMPS DROP BELOW NORMS
TO SOME DEGREE. CLOUDS/PASSING SNSH WILL MODIFY TEMPS AT NIGHT. MAIN
QPF THIS PERIOD WILL BE ASSOCIATED WITH LES ACROSS SNOWBELT. SOME
CONTRIBUTING FACTORS OF NOTE: LAKE INDUCED CAPE SHOULD REACH BETWEEN
500/750 J/KG INDICATING MODERATE LVLS OF INSTABILITY...LAKE INDUCED
EQL MAINTAINS 10/15K FT THROUGHOUT PERIOD WITH NO INVERSION ISSUES
TO RESTRICT GROWTH OF LAKE CLOUDS...AND AT LEAST A 24/36 HR PERIOD
OF OMEGA WITHIN THE FAVORED DENDRITIC GROWTH ZONE. AS USUAL...ANY
SIGNIFICANT DEVIATIONS IN LOW LVL TRAJECTORY OFF LAKE WILL AFFECT
THE INTENSITY/LOCATION OF BEST PLUMES. MDL SIGNALS HAVE BEEN
CONSISTENT THAT SIGNIFICANT ACCUMULATION IS BECOMING MORE LIKELY
GIVEN SYNOPTIC PATTERN...TIME OF YEAR WITH OPEN LAKE....AND
ANOMALOUS 85H TEMPS. OTHERWISE SHORTWAVES EMBEDDED WITHIN DEEP
CYCLONIC CIRCULATION SHOULD ACT UPON RELATIVELY MOIST COLUMN TO
GENERATE PERIODIC SNSH/FLURRIES IN MOST AREAS. /CANNON
&&
.POINT TEMPS/POPS...
DLH 23 30 16 21 / 40 30 10 20
INL 17 27 12 16 / 70 40 10 20
BRD 24 32 18 21 / 20 30 10 20
HYR 24 32 17 22 / 20 20 30 20
ASX 24 33 19 24 / 40 40 40 40
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR MNZ010>012-
018-019-021.
WI...NONE.
LS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM CST
THURSDAY FOR LSZ121-146>148.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 PM CST
WEDNESDAY FOR LSZ140>145.
&&
$$
