FXUS63 KDLH 301746 AAA
AFDDLH
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
1146 AM CST MON NOV 30 2009
.UPDATE...18 Z TAF DISCUSSION BELOW...
&&
.AVIATION...MVFR CIGS WITH OCCASIONAL IFR VISBYS WILL AFFECT KINL
AND KHIB FOR A FEW HOURS IN -SN...WITH MVFR AT KDLH AND KHYR.
EXPECT -SN TO PASS THROUGH KDLH BETWEEN 18-21Z...20-23Z AT KHYR.
EXPECT MVFR TO LINGER A BIT BEFORE A DRY SLOT AND SURFACE HIGH
BUILD IN OVERNIGHT. POTENT UPPER LEVEL DISTURBANCE WILL IMPACT
KINL AND KHIB DURING THE 12Z-18Z TIME FRAME...WITH MVFR
EXPECTED...IFR IN MODERATE SN IS EXPECTED AT KINL NEAR THE END OF
THE PERIOD WHEN THE BEST UPPER FORCING AND FGEN IS COINCIDENT.
/DONOFRIO
&&
.PREV DISCUSSION... /ISSUED 918 AM CST MON NOV 30 2009/
UPDATE...SNOW HAS BEGUN ALONG THE INTERNATIONAL BORDER AREA WITH
LIGHT SNOW REPORTED AT KINL AND FROM LITTLEFORK OBSERVER. THIS IS
IN AREA OF PVA FROM PASSING UPPER TROF AND LFQ OF UPPER LEVEL JET
DIVING SE FROM THE CANADIAN PLAINS. HAVE UPDATED TO ACCOUNT FOR
THE SNOW ONSET AND ADJUSTED POPS ELSEWHERE FOR THIS MORNING. THE
AFTERNOON GRIDS STILL LOOK GOOD. ALSO ADJUSTED MAX TEMPS WHERE
NEEDED AS UPPER LIMITS OF EARLIER FORECAST RANGE IS BEING MET
ACROSS THE SOUTHERN TIER OF THE FA. /GSF
PREV DISCUSSION... /ISSUED 323 AM CST MON NOV 30 2009/
DISCUSSION...
THRU TUE...
SFC RIDGING WILL BE OVERRUN BY AN UPR LVL S/WV TDA WHICH IS EXPECTED
TO DEVELOP A BROAD SFC TROF BY MIDDAY. AMS REMAINS DRY...BUT UPR LVL
LIFT SUFFICIENT TO JUSTIFY SLGT TO LOW CHC POPS FOR MOST AREAS. BEST
CHC FOR -SN WILL BE ARROWHEAD THIS AFTN WITH PSG OF SFC TROF AND UPR
LVL VORT MAX. ANY ACCUMS SHUD BE LESS THAN AN INCH. BRIEF PD OF
RIDGING TNGT FOR MAINLY DRY CONDS. ANY LES ALG S SHORE WILL BE WEAK
AND SHORT LIVED. MUCH STRONGER S/WV APPROACHES ON TUE ACCOMPANIED BY
STRONG SFC SYSTEM. GFS/CN/ECMWF IN REASONABLY CLOSE AGMT ON POSITION
OF SFC LOW...WITH THE NAM A BIT SLOWER AND FARTHER N. MAIN SNOW BELT
WILL BE ACRS NRN PART OF CWA...GENERALLY ALG AND N OF THE IRON
RANGE. SNOW ACCUMS DIFFICULT TO DETERMINE AT THIS POINT...BUT
SEVERAL INCHES ARE LIKELY DUE MAINLY TO THE STRONG DYNAMICS AND IN
SPITE OF THE LACK OF A GOOD MSTR SOURCE. MUCH WILL DEPEND ON FINAL
TRACK OF THE LOW AND POSITION OF THE WFNT. EXPECT A SMALL INCRS IN
TEMPS TDA AND TUE IN WAA PATTERN AHD OF THE SFC LOW. RAPID COOL DOWN
THEREAFTER WITH THE BUILDING OF A HIGH AMPLITUDE RIDGE OVR THE W
COAST AND SHIFT IN TRAJECTORY TO ARCTIC REGIONS. /04
TUE NGT THRU FRI...
A WELL DEVELOPED MID LVL TROF/ASSOCIATED SFC LOW WILL CROSS NRN
TIER OF CWA AT BEGINNING OF PERIOD. MDLS DIVERGE SOMEWHAT ON
EXACT TRACK OF MAIN FORCING HOWEVER AN AREA OF ACCUMULATING SNOW
WILL CROSS THE NRN THIRD OF THE CWA TUESDAY NIGHT. SNOW MAY BE
ACCOMPANIED BY SOME INCREASINGLY STRONGER NW WINDS BY MORNING.THIS
SYSTEM WILL OPEN THE DOOR TO A PROGRESSION OF COLDER AIR FOR THE
REMAINDER OF THE WEEK. A LARGE AMPLITUDE MID LVL TROF WILL
DOMINATE THE REGIONAL PATTERN THROUGH THE REST OF THE WEEK. THERE
ARE SOME MINOR DIFFERENCES BETWEEN GFS/EC/GEM REGARDING AXIS OF
MID LVL TROF AND TIMING OF INDIVIDUAL SHORTWAVES WITHIN DEEPLY
CYCLONIC FLOW. WITH PROGRESSION OF COLDER AIR SOUTH FROM PLAINS OF
CANADA EXPECT SNSH TO BE COMMON THROUGHOUT THE PERIOD. OVERALL
SYNOPTIC PATTERN WILL PROMOTE INCREASING POTENTIAL OF SIGNIFICANT
LAKE EFFECT SNOW ACROSS WI SNOWBELT. BUFKIT LAKE EFFECT PARAMETERS
INDICATE A MAXIMUM INSTABILITY PERIOD BETWEEN LATE WEDNESDAY INTO
EARLY FRIDAY. DURING THIS PERIOD LAKE INDUCED CAPE WILL RISE ABOVE
500J/KG. MODERATE INSTABILITY VALUES ON THE COLLIER INDEX WILL
OCCUR AS 85H TEMPS DROP BELOW -10C AND LAKE INDUCED EQL REACHES
OVER 10K FT. VARIOUS QPF/LIQUID TO SNOW RATIO TECHNIQUES AND SNOW
AMNT ALGORITHMS SUGGEST AMOUNTS IN EXCESS OF SIX INCHES MAY BE
EASILY REACHED. STREAMLINE/TRAJECTORY IN LOW LEVELS STILL
UNCERTAIN AT THIS TIME SO WILL NEED TO MONITOR DEVELOPMENT OF LOW
LVL FLOW AS CORE OF INSTABILITY IS REALIZED. /CANNON
&&
.POINT TEMPS/POPS...
DLH 36 26 35 23 / 40 10 30 40
INL 33 21 30 18 / 80 30 60 40
BRD 36 26 38 24 / 30 10 10 20
HYR 38 27 42 26 / 40 10 10 20
ASX 39 26 41 28 / 50 20 30 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
