FXUS63 KDLH 051212
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
612 AM CST SAT DEC 5 2009
.AVIATION.../12Z TAF ISSUANCE/
AN UPPER LEVEL TROUGH WILL DIG SOUTH OVER THE FORECAST AREA TODAY
AND TONIGHT. AS A RESULT...AREAS OF LOW CLOUDS WITH MVFR CIGS WILL
LINGER OVER THE FCST AREA THROUGH TONIGHT. SCATTERED SNOW
SHOWERS WILL ALSO CONTINUE TO AFFECT THE CWA WITH IFR/MVFR
VSBYS...ESPECIALLY INVOF AREA LAKES AND LAKE SUPERIOR. THE SNOW
SHOWERS SHOULD DISSIPATE TONIGHT...EXCEPT ALONG THE SOUTHSHORE OF
LAKE SUPERIOR.
&&
.PREV DISCUSSION... /ISSUED 341 AM CST SAT DEC 5 2009/
DISCUSSION...MAIN FOCUS TODAY IS ON MESOSCALE SNOW BANDS
AT 3 AM...KDLH RADAR CONTINUED TO SHOW SNOW BANDS THAT HAD
DEVELOPED OFF INLAND LAKES ON FRIDAY. THE LARGEST BAND WITH THE
HEAVIEST SNOW WAS LOCATED JUST OFFSHORE ON THE WESTERN TIP OF LAKE
SUPERIOR. THIS BAND APPEARED TO BE PRIMED BY LAKE EFFECT SNOW
BANDS OFF MILLE LACS LAKE. REPORTS OF 1 TO 2 INCHES HAD BEEN
RECEIVED AS OF EARLY THIS MORNING...MAINLY IN AREAS ADJACENT/EAST
OF LARGE INLAND LAKES SUCH AS...LAKE OF THE WOODS...PELICAN
LAKE... VERMILION LAKE...CASS LAKE...LEECH LAKE...MILLE LACS LAKE
AND ALSO ISLAND LAKE RESERVOIR NEAR DULUTH. WITH A VERY WARM
NOVEMBER...THE ICE FREE LAKES WILL CONTINUE TO PRODUCE LAKE EFFECT
SNOW BANDS DUE TO THE COLD AIR BLOWING ACROSS THE LAKES.
THE WRF EMS 5KM MODEL OUTPUT IMPRESSIVELY PICKS OUT SOME OF THE
INLAND LAKE SNOW BANDS...AS WELL AS THE DOMINANT WESTERN LAKE
SUPERIOR SNOW BAND...WHICH STRETCHES FROM SW-NE JUST OFFSHORE FROM
PORT WING...CORNUCOPIA AND HERBSTER. THIS BOUNDARY LAYER
CONVERGENCE BAND IS EXPECTED TO CONTINUE THROUGH THE MORNING. THE
WRF EMS 900 MB RH/OMEGA INDICATES THAT THE BAND WILL GRADUALLY
DIMINISH ON THE SW BACK EDGE...BUT MAY GRADUALLY MIGRATE ONSHORE.
IT SHOULD BE CLOSE...BUT THE WRF EMS DOES INDICATE A POSSIBLE PUSH
TOWARD THE SHORELINE AS THE MORNING WEARS ON. THE SUPPORT FOR THE
SNOW BAND APPEARS TO WANE DURING THE AFTERNOON...SO WILL HIT POPS
AND SNOW AMOUNTS HARDEST DURING THE MORNING.
TODAY...WILL CONTINUE WITH SMALL POPS ACROSS MOST OF THE AREA.
THE GOING ZONES/GRIDS FROM LAST EVENING HAD A GREAT HANDLE ON THE
MESOSCALE FORECASTING TRENDS FOR THE DAY...SO WILL CHANGE VERY
LITTLE IN THIS REGARD. COULD SEE 2 TO 5 INCHES OF LOCALIZED
SNOWFALL ALONG THE BAYFIELD COUNTY SHORELINE IF THE BAND DOES
INDEED MIGRATE INLAND. IF NOT...AMOUNTS SHOULD BE LIGHT.
ELSEWHERE...AMOUNTS SHOULD GENERALLY BE LIGHT UNLESS MORE
ORGANIZED BANDS DEVELOP. SOME BREAKS IN THE CLOUDS HAVE DEVELOPED
TODAY...BUT WITH LOW LEVEL MOISTURE AND THE PRESENCE OF THE UPPER
LEVEL TROUGH...WE SHOULD STILL SEE A FAIR AMOUNT OF CLOUDS.
FOR TONIGHT AND SUNDAY...FAIRLY QUIET WEATHER IS EXPECTED FOR
TONIGHT. COULD BE SOME LIGHT LAKE EFFECT SNOW ACROSS THE SOUTH
SHORE...AND PERHAPS DOWNWIND OF SOME OF THE INLAND LARGE LAKES.
MONDAY THRU FRIDAY...THE MAIN FORECAST CONCERN FOR THE EXTENDED
FORECAST IS A LOW PRESSURE SYSTEM PROGGED TO DEVELOP OVER THE
SOUTHERN PLAINS MONDAY NIGHT AND TUESDAY...THEN LIFT NEWD OVER THE
MIDWEST TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THE 00Z GFS TAKES
THE SFC LOW ACROSS ILLINOIS/INDIANA/OHIO...BUT HAS AN INVERTED
TROUGH THAT EXTENDS NORTHWEST OF THE LOW ACROSS WISCONSIN. BECAUSE
OF THIS INVERTED TROUGH AND ENHANCED LIFT ASSOCIATED WITH THE
TROUGH...THE PRECIPITATION SHIELD EXTENDS FARTHER NORTHWEST OF THE
MAIN LOW THAN WHAT IS USUAL. THE GFS ALSO SHOWS SOME LAKE ENHANCED
SNOWFALL...INITIALLY ALONG THE NORTHSHORE TUESDAY NIGHT INTO
WEDNESDAY...THEN ALONG THE SOUTHSHORE WEDNESDAY NIGHT AND
THURSDAY. IF THE CURRENT MODEL RUN VERIFIES...SNOW AMTS WILL RANGE
FROM 4 TO 12 INCHES...WITH HIGHEST AMOUNTS ACROSS OUR WI
ZONES...AND LESSER AMOUNTS ACROSS OUR NWRN ZONES. BEFORE AND AFTER
THE STORM...CONDITIONS SHOULD BE MAINLY DRY...EXCEPT FOR LAKE
EFFECT SNOW SHOWERS ACROSS THE SNOWBELT OF NWRN WI.
AVIATION.../06Z TAF ISSUANCE/
MAINLY MVFR CIGS TO CONTINUE THROUGH THE TAF PD...THOUGH THERE MAY
BE SOME TEMPO IMPROVEMENTS TO VFR. VSBYS WILL ALSO BE IN THE MVFR
RANGE IN SNOW SHOWERS...EVEN DROPPING TO IFR IN THE HEAVIER
SQUALLS. WINDS WILL BE LIGHT WITH A SOUTHWESTERLY COMPONENT...
BECOMING VEERING NORTHWEST AND EVENTUALLY NORTH THROUGH TIME.
&&
.POINT TEMPS/POPS...
DLH 22 10 20 9 / 20 10 10 10
INL 16 6 16 4 / 20 10 10 10
BRD 22 8 20 7 / 20 10 10 10
HYR 24 11 24 7 / 20 20 10 10
ASX 26 16 25 13 / 20 20 30 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
BERDES/BERDES/BERDES
