FXUS63 KDLH 102323
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
523 PM CST THU DEC 10 2009
.UPDATE...FOR 00Z TAFS
&&
.AVIATION...UPDATE FOR 00Z TAFS
NOT MUCH CHANGE FROM PVS TAF SET. GNRLY VFR CONDS THRU TAF
PD...EXCEPT FOR SOME PATCHY MVFR CIGS LINGERING THRU THIS EVE.
WINDS WILL RETAIN A WLY COMPONENT UNTIL LATE FRI AFTN WHEN THEY
WILL START SHIFTING TO THE S ON THE BACK SIDE OF THE SFC RIDGE.
&&
.PREV DISCUSSION... /ISSUED 341 PM CST THU DEC 10 2009/
DISCUSSION...
SHORT TERM FOCUS ON OVERNIGHT TEMPS/WIND CHILLS ALONG WITH A NARROW
LES BAND OVER FA NRN BAYFIELD WISCONSIN. A POCKET OF -24C H85 TEMPS
SLIDES SE THIS EVENING...CENTERING OVER THE NORTHLAND THROUGH 12Z
FRIDAY. FOR OVERNIGHT LOWS...WENT CLOSE OR SLIGHTLY BLW OBSERVED
TEMPS FROM LAST NIGHT. A SLIGHTLY STRONGER WRLY FLOW WILL RESULT IN
WIDESPREAD WIND CHILL READINGS OF 20 TO 30 BELOW ZERO. ISSUED A WIND
CHILL ADVISORY FOR ENTIRE CWA IN EFFECT FROM 9 PM THIS EVENING
THROUGH 9 AM FRIDAY MORNING. REFER TO LATEST WSW FOR MORE DETAILS.
TRIMMED BACK TIMING/SN AMOUNTS OF LES ADVISORY FOR EXTREME NORTHERN
BAYFIELD COUNTY. TIME HEIGHT CROSS SECTIONS AND 850-700 MB RH FIELDS
FROM NAM12 SUGGEST THE ALREADY LIMITED MOISTURE TAPPERS OFF QUICKLY
AFT 12Z FRI AS WINDS BECOME SW AND ANY LINGERING LES SHOWERS WILL BE
CONFINED OVER THE WATER OF LK SUP. ALTHOUGH CURRENT RADAR IMAGERY IS
PICKING UP ON THE NARROW CORRIDOR OF LIGHT SN...A SNOWFALL OBSERVER
AT BARK ISLAND ON THE WRN EDGE OF THE BAYFIELD PENINSULA REPORTED
ONLY FLURRIES ATTM. HOWEVER...OMEGA FIELDS IN THE AREA INCREASE AFT
00Z WHILE AND FCST SOUNDINGS SHOW FAVORABLE LAPSE RATES TO 850 MB
AND SOME POSITIVE AREA. LIMITING FACTOR FOR ACCUMULATIONS GREATER
THAN 2-4 INCHES WILL BE THE ARCTIC AIR MASS AND SNOWFLAKE TYPE. WITH
925-850 TEMPS ON THE ORDER OF -18 TO -24C...SMALL PLATES/COLUMNS ARE
EXPECTED...WHICH WILL HAVE A HARD TIME ACCUMULATING.
THE COLD AIR TONIGHT WILL ALSO BRING POSSIBLE LIGHT LAKE EFFECT SNOW
SHOWERS/FLURRIES ON THE ERN SHORES OF THE LARGER OPEN LAKES IN
THE FA. THIS INCLUDES LAKE OF THE WOODS...MILLE LACS...ISLAND
LAKE...AND CHIPPEWA LAKE NEAR HAYWARD. WITH SOME UNCERTAINTY IN THE
ICE COVER ON THESE LAKES...ONLY INTRODUCED FLURRIES TONIGHT TO
ACCOUNT FOR THE ISOLATED LAKE INDUCED SNOW. EVENING SHIFT WILL
NEED TO MONITOR FOR ANY ACCUMULATING SNOW. CONTINUED WARMING
TREND TROUGH WEEKEND. FCST STILL RUNNING 5-10 F BEHIND GUIDANCE
FOR SAT NIGHT/SUN.
EXTENDED...SUNDAY NIGHT THROUGH THURSDAY
MODEL DIFFERENCES SHOW UP EARLY IN THE PERIOD...WITH THE GFS MUCH
STRONGER AND FURTHER NORTH WITH AN AREA OF LOW PRESSURE AFFECTING
THE NORTHLAND SUNDAY NIGHT INTO MONDAY. WE WENT CLOSER TO THE
ECMWF...WHICH HAS SOME SUPPORT FROM THE GEM. THERE WILL BE A CHANCE
FOR SNOW SUNDAY NIGHT INTO AT LEAST MONDAY MORNING...BUT AMOUNTS
LOOK LIGHT...EXCEPT ALONG PORTIONS OF THE SOUTH SHORE WHICH MAY SEE
SOME ACCUMULATING SNOW IF WINDS BECOME NORTHERLY ENOUGH BEHIND THE
LOW. THE GFS IS THEN QUITE A BIT COLDER BEHIND THE LOW ON MONDAY.
THE GEM AND ECMWF ARE CLOSER AND WE DID NOT GO AS COLD.
THE MODELS GET INTO BETTER AGREEMENT FOR THE MIDDLE OF NEXT WEEK
WITH HIGH PRESSURE OVER THE AREA. THERE MAY BE A FEW PERIODS OF LES
ALONG PORTIONS OF THE SOUTH SHORE...BUT THE AIRMASS DOES LOOK TO
BECOME QUITE DRY WITH THE HIGH. WE KEPT DAY 7 OR NEXT THURSDAY DRY
ATTM...BUT THE ECMWF DOES SHOW SOME SIGNIFICANT WAA...WHICH WOULD
RESULT IN A CHANCE FOR PRECIP.
PREV DISCUSSION... /ISSUED 1136 AM CST THU DEC 10 2009/
AVIATION...18Z TAFS
VFR CONDITIONS WERE OCCURRING OVER MOST AREAS THIS MORNING. THE
MODELS DO SHOW SOME CLOUDS DEVELOPING BETWEEN 20Z-22Z WITH BASES
FROM 1500-2500 FEET...BUT CONFIDENCE IN THAT IS MARGINAL AT THIS
TIME. THE AIRMASS IS QUITE COLD...SO WITH SOME HEATING WE COULD
DEVELOP SOME CUMULUS OR STRATOCUMULUS. HOWEVER...THE SUN ANGLE IS
SO LOW. WE DID ADD A TEMPO GROUP FOR MOST TAF SITES FOR THIS MVFR
DECK...AND WILL UPDATE IF IT BECOMES MORE WIDESPREAD. THE MVFR
DECK IF IT DOES DEVELOP WOULD LINGER THIS EVENING.
WINDS WILL BE WESTERLY FROM 5 TO 15 KT.
&&
.POINT TEMPS/POPS...
DLH -7 9 1 19 / 10 10 10 20
INL -14 4 -3 13 / 10 10 20 20
BRD -8 10 -1 17 / 10 10 10 20
HYR -10 6 -5 18 / 10 10 10 10
ASX -5 8 -3 20 / 10 10 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST FRIDAY
FOR MNZ010>012-018>021-025-026-033>038.
WI...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST FRIDAY
FOR WIZ001>004-006>009.
LAKE EFFECT SNOW ADVISORY UNTIL 9 AM CST FRIDAY FOR WIZ002.
LS...SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR LSZ121-146>148.
SMALL CRAFT ADVISORY UNTIL 4 PM CST FRIDAY FOR LSZ145.
&&
$$
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