FXUS63 KDLH 221201
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
601 AM CST TUE DEC 22 2009
.AVIATION...12Z TAFS
MVFR CEILINGS WERE AFFECTING PORTIONS OF THE NORTHLAND FROM THE
SOUTH SHORE OF LAKE SUPERIOR...PARTS OF THE ARROWHEAD...AND FROM
THE TWIN PORTS NORTHWEST THROUGH KGPZ TO KINL. VFR CONDITIONS WERE
OCCURRING FROM THE KBRD AREA...EAST TO KHYR AND KPBH. THERE WAS
ALSO A HOLE OF VFR CONDITIONS OVER KELO...KCDD...KCQM AS OF 12Z.
OVERALL...THIS CLOUD IS MOVING WITH THE LOW LEVEL MEAN FLOW TO
THE NORTHWEST AND CURRENT TRENDS HAS IT MOVING OUT OF KDLH AND
KINL IN A COUPLE HOURS. THE CLOUD MAY ALSO CLEAR OUT OF KHIB LATER
THIS MORNING. HOWEVER...MORE MVFR CEILINGS WERE WORKING WEST FROM
ONTARIO AND THE ARROWHEAD REGION. MORE MAY REFORM OVER LAKE
SUPERIOR THROUGH THE DAY...AND WITH SOUTHEAST 1000-850MB
FLOW...WOULD KEEP THEM IN KHIB AT TIMES. OVERNIGHT...EXPECT THE
MVFR CEILINGS TO REFORM AND SPREAD TO MOST AREAS.
&&
.PREV DISCUSSION... /ISSUED 344 AM CST TUE DEC 22 2009/
DISCUSSION...LARGE SFC HIGH OVER ONTARIO REMAINS THE DOMINANT
WEATHER FEATURE THIS MORNING. EASTERLY BDRY LYR FLOW ACROSS LAKE
SUPERIOR HAS ALLOWED AREAS OF LOW CLOUDS TO FORM. CLOUDS ARE
MOVING WEST AND NORTHWEST AROUND THE PERIPHERY OF THE HIGH.
OCCASIONALLY A FLAKE WILL SHAKE OUT OF THE CLOUDS BUT OVERALL
MAINLY CLOUDS AT THIS POINT. AREAS OF CLOUDS HAVE PRODUCED A LARGE
VARIATION IN TEMPS ACROSS REGION THIS MORNING...RANGING FROM 23 AT
KDYT WITH CLOUDS/ONSHORE FLOW... TO -6 AT KHYR AND KPBH UNDER
CLEAR/CALM CONDITIONS.
TODAY/TONIGHT/WEDNESDAY....MID LVL RIDGING...WITH LACK OF SYNOPTIC
SCALE ASCENT...COMBINED WITH LOW LEVEL ANTICYCLONIC FLOW WILL KEEP
REGIONAL WEATHER PATTERN QUIET. EXCEPTION IS WHERE PERSISTENT
ONSHORE FLOW MAY YIELD EXTENSIVE CLOUD COVER AND SOME LT
SNOW/FLURRIES. MAJORITY OF MESOSCALE MDLS AND PERTINENT
FIELDS...OMEGA/RH/SIM REFLECTIVITY/BDRY LYR WIND...SUGGEST AN AREA
OF PRECIP WILL TRY TO FORM ALONG NSHORE AND ADVECT NORTH WITH TIME.
DIFFERENCES EXIST ON PLACEMENT OF BEST LOW LEVEL MSTR FLUX. NAM12
KEEPS MAIN AXIS FOCUSED NEAR A KTWM VICINITY...WHILE REG GEM PUSHES
BEST AXIS NORTH INTO COOK COUNTY NEXT 24HRS. LATEST WRFARW KEEPS
AN AREA IN BETWEEN THE TWO. MINOR ACCUMULATION AT THIS POINT WITH
MARGINAL LAPSE RATES AND LOW INVERSION HEIGHT. HOWEVER WILL NEED
TO MONITOR FOR POTENTIAL OF INVERSION LIFTING ENOUGH TO ALLOW MORE
ACCUMULATION. MID LVL RIDGE AXIS WILL SHIFT FAR ENOUGH EAST
WEDNESDAY AFTERNOON TO ALLOW AN INCREASE IN MID/HIGH LVL CLOUDS.
EXTENDED...WEDNESDAY NIGHT THROUGH MONDAY
EMPHASIS IN THE EXTENDED IS ON A STORM THAT WILL AFFECT...IN SOME
WAY...MUCH OF THE NORTHLAND THURSDAY THROUGH FRIDAY NIGHT OR
SATURDAY.
MOST OF THE MODELS HAVE MADE A NORTH AND WEST SHIFT IN THE TRACK OF
THE LOW...WHICH WOULD SUGGEST OUR WESTERN ZONES HAVE A BETTER CHANCE
AT RECEIVING SIGNIFICANT SNOWFALL THAN WHAT LAST NIGHTS MODELS
SUGGESTED.
THE MODELS TAKE THE UPPER WAVE COMING INTO THE NORTHWEST CONUS
ATTM...INTO THE 4 CORNERS REGION BY 12Z WED...THEN UP ANYWHERE
FROM THE SOUTHERN PLAINS TO THE CENTRAL PLAINS BY 12Z THU...AND INTO
THE MO/IA AREA BY 12Z FRI. THE MODELS DIVERGE FURTHER ON SATURDAY AS
THE GFS IS MORE PROGRESSIVE LIFTING THE UPPER LOW THROUGH
WISCONSIN...VERSUS THE ECMWF THAT STALLS THE LOW IN WISCONSIN.
AT THE SURFACE...MOST OF THE MODELS DEEPEN THE SURFACE LOW ON
THURSDAY...THEN WEAKEN THE LOW BY FRIDAY AS IT MOVES INTO WISCONSIN.
THIS NORTH AND WEST SHIFT IN THE LOW TRACK CREATES A NEW SET OF
ISSUES ACROSS OUR CWA. FIRST OFF...IT ALLOWS WARMER AIR TO MOVE
CLOSER TO OUR CWA...AND MAY BRING A CHANCE FOR MIXED SNOW OR SLEET
AND FREEZING RAIN TO PARTS OF NORTHWEST WISCONSIN. THIS IS GOING TO
BE A PROLONGED EVENT...AND DURING A TIME OF LIGHTER PRECIP...AREAS
OF FREEZING DRIZZLE MAY OCCUR. THIS WOULD BE MOST LIKELY IN
NORTHWEST WISCONSIN. THE SHIFT IN TRACK ALSO GIVES THE WESTERN CWA A
BETTER CHANCE FOR HEAVY SNOW.
WE HAVE ISSUED A WINTER STORM WATCH FOR MUCH OF OUR CWA FROM 12Z
THURSDAY THROUGH 06Z SATURDAY. WE EXCLUDED OUR FAR NORTHERN ZONES
AND A PART OF THE ARROWHEAD...WHERE WE HAVE THE LEAST CONFIDENCE
THAT A WARNING MAY EVENTUALLY BE NEEDED. CONFIDENCE IN THE WATCH IS
ALSO LOWER OVER OUR SOUTHEAST ZONES...FROM PHILLIPS/PARK FALLS...TO
HAYWARD...AND UP TO ASHLAND...AND OVER TO HURLEY. THIS AREA COULD
EXPERIENCE MIXED PRECIP WHICH WOULD CUT DOWN ON SNOW AMOUNTS.
ALSO...THE NORTH AND WEST TREND OF THE LOW COULD CONTINUE PUTTING
THE HIGHER PRECIP AMOUNTS FURTHER WEST. THIS STORM IS STILL A LONG
WAY OUT...AND WE'VE SEEN RUN TO RUN DIFFERENCES IN ALL THE MODELS.
TIMING OF ANY EVENTUAL WARNINGS AND ADVISORIES WILL VARY FROM WHAT'S
IN THE CURRENT WATCH...NAMELY STARTING LATER ON THURSDAY OR EVEN
THURSDAY EVENING IN NORTHERN AREAS.
AVIATION.../06Z TAF ISSUANCE/
WEAK FLOW CONTINUES TO RESULT IN BKN TO OVC STRATUS ACROSS MUCH OF
NE MN AND NW WI. SOME BREAKS IN THE LOW STRATUS SEEN AT KHYR AND
KBRD. SOME QUESTION AS TO WHETHER OR NOT CIGS WILL FILL IN AGAIN
ON TUE ACROSS THE SRN PART OF THE CWA. CONFIDENCE IS HIGHER FOR
PERSISTENT MVFR CIGS ACROSS NORTHERN TERMINALS THROUGH THE TAF
PD...AS INDICATED BY LOW LVL CONDENSATION PRES DEFICITS.
&&
.POINT TEMPS/POPS...
DLH 27 18 26 19 / 10 10 10 20
INL 18 9 22 14 / 10 10 10 10
BRD 24 19 25 19 / 10 10 10 60
HYR 25 14 26 19 / 10 10 10 40
ASX 28 16 26 20 / 10 10 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH FRIDAY EVENING
FOR MNZ018>020-025-026-033>038.
WI...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH FRIDAY EVENING
FOR WIZ001>004-006>009.
LS...NONE.
&&
$$
MELDE/CANNON
