FXUS63 KDLH 040619
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1219 AM CST FRI DEC 4 2009
.AVIATION.../06Z TAF ISSUANCE/
EXPECT MAINLY MVFR CIGS THROUGH THE TAF PD. SNOW SHOWERS WILL
REMAIN THROUGH THE PERIOD WITH THE ACCOMPANYING SHORTWAVE
TROUGH DROPPING SOUTH FROM ONTARIO...WITH VSBYS VARYING IN THE
SNOW SHOWERS. BEST CHANCE FOR SEEING IFR VSBYS IN -SN WILL BE AT
KINL.
&&
.PREV DISCUSSION... /ISSUED 808 PM CST THU DEC 3 2009/
UPDATE...
INCREASED POPS FOR TONIGHT/TOMORROW...AS SNOW SHOWERS CONTINUE TO
BE FAIRLY WIDESPREAD ACROSS THE NORTHLAND. AREAS ALONG THE
BORDERLAND HAVE THE BEST SHOT AT SEEING ACCUMULATING SNOW UP TO AN
INCH TONIGHT...AND POSSIBLY AN ADDITIONAL INCH ON FRIDAY. WITH A
WEST NORTHWEST WIND COMPONENT...SOME LAKE ENHANCEMENT OFF OF LAKE OF
THE WOODS COULD CONTRIBUTE TO THE HIGHER TOTALS HERE. ANOTHER
SHORTWAVE...AS DEPICTED ON H2O VAPOR SATELLITE IMAGERY ACROSS WRN
ONTARIO...IS DIVING SOUTHWARD AND WILL PASS THROUGH THE FA THROUGH
THE DAY FRIDAY...KEEPING THE SNOW SHOWERS ONGOING. AREAS OUTSIDE
OF THE NORTHERN ZONES WILL SEE SNOW ADD UP TO A TRACE TO HALF AN
INCH OR SO.
PREV DISCUSSION... /ISSUED 335 PM CST THU DEC 3 2009/
DISCUSSION...
WE HAVE CANCELED THE LAKE EFFECT SNOW ADVISORY WITH THIS FORECAST
PACKAGE. WHILE 850 TEMPS HAVE BEGUN TO COOL TO -13C...FLOW HAS
BECOME MORE BACKED...AND DEEPER SATURATION JUST HAS NOT COME TO
FRUITION. A COUPLE OF INCHES ARE STILL POSSIBLE WITH CONTINUED
CAA...BUT AS THE CAA INCREASE FLOW WILL BECOME MORE BACKED AND
PLACE THE BEST CONVERGENCE AXIS EAST OF THE AREA. THE LOCAL WRF
MODEL STILL SUGGESTS A FEW BANDS NEAR THE IRONWOOD AREA.
OTHER THAN THE LAKE EFFECT...FLURRIES AND LIGHT SNOW SHOWERS HAVE
BEEN OCCURRING OVER THE NORTHLAND TODAY...WITH PIECES OF ENERGY
PUSHING SSE BEHIND A CUT OFF UPPER LOW ALONG THE MN/IA BORDER. A
MORE SIGNIFICANT VORT MAX EMANATING FROM THE NORTHERN CUT OFF LOW
JUST SOUTH OF HUDSON BAY WILL PUSH INTO THE BORDERLAND TONIGHT. WE
INCREASED POPS ACCORDINGLY IN THE NORTHERN TIER TONIGHT. THE BEST
ENERGY/FORCING WILL LINGER IN THE NORTH BEFORE SHIFTING SE DURING
THE AFTERNOON. 1-2 INCHES OF SNOW ARE POSSIBLE NORTH OF THE IRON
RANGE...EXTENDING INTO THE ARROWHEAD. LIGHTER ACCUMULATIONS ARE
EXPECTED FURTHER SOUTH. VERY LITTLE IS SEEN IN THE WAY OF SURFACE
BOUNDARIES AT THIS TIME.
THE UPPER LOW THAN MEANDERS ALONG THE INTERNATIONAL BORDER AND
STRETCHES THE ASSOCIATED VORTICITY...KEEPING ANY REAL FORCING
NORTH AND EAST...WHILE WAA ENSUES IN OUR WESTERN ZONES FRIDAY
NIGHT INTO SATURDAY. THIS IS AHEAD OF AN INVERTED TROUGH IN THE
PLAINS THAT ORGANIZES IN THE PLAINS. OUR WESTERN ZONES MAY BREAK
OUT OF THE CLOUDS FOR A BIT SATURDAY...WITH AREAS NORTH STAYING
MOSTLY CLOUDY. A SMALL WARM UP WILL BE SEEN IN THE SOUTH AND
WEST...BUT NO ONE IS EXPECTED TO GET OUT OF THE 20S.
OF NOTE IN THIS FORECAST PACKAGE IS THE POTENTIAL FOR LAKE EFFECT
SNOW IN THE TWIN PORTS AREA AND EAST TO THE BAYFIELD PENINSULA ON
LATE SATURDAY NIGHT AND SUNDAY. PREVIOUS FCST STARTED TO HINT AT
THIS IDEA. DEPENDING ON THE TRACK OF THE LOW...AS THE CENTER OF
LOW PRESSURE ASSOCIATED WITH THE INVERTED TROUGH PUSHES NEAR SW
MN...WINDS SHIFT AROUND TO THE ENE...PROVIDING A NICE FETCH DOWN
THE LAKE...SOME SEEDING FROM LAKE NIPIGON...AND A WELL DEFINED
CONVERGENCE AXIS SETTING UP. WHILE THE TIMING AND LOCATION WILL
NEED REFINEMENT AS THE WEEKEND APPROACHES...WE HAVE INCREASED
POPS/QPF TO CHANCE TO ACCOUNT NOT ONLY FOR PRECIPITATION ASSC
WITH THE INVERTED TROUGH...BUT ALSO THE LAKE EFFECT POTENTIAL
ALONG THE NEAR NORTH SHORE...TWIN PORTS...AND SOUTH SHORE. LATEST
NAM COBB OUTPUT GIVES KDLH OVER 4 INCHES OF SNOW DURING THE 0Z
SUNDAY TO 0Z MONDAY TIME FRAME...THE 12Z VERSION WAS GIVEN KDLH
3-3.5. THE GFS HINTS AT SOME SNOW...BUT THE LAST FEW RUNS ARE ONLY
HINTING AT 0.5" TO 1".
EXTENDED...SUNDAY NIGHT THROUGH THURSDAY.
MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE EXTENDED PERIOD.
HAVE GONE WITH A BLEND AS A RESULT...LEANING TOWARD THE 12Z ECMWF
WHICH HAS BEEN THE MODEL OF CHOICE. LES POTENTIAL SUNDAY NIGHT
THROUGH MONDAY NIGHT FROM THE TWIN PORTS E ALONG THE SOUTH SHORE OF
LAKE SUPERIOR. NE FLOW POINTS TO SOME POSSIBLE ACCUMULATIONS...BUT
QUESTION IS HOW MUCH COLD AIR/DEEP LAYER SATURATION PLAY A PART.
HAVE LOW POPS REGARDLESS. SOME LOW POPS ELSEWHERE DURING THIS TIME
AS UPPER LEVEL ENERGY IMPACTS THE FA. RELIED ON HPC GUIDANCE TUESDAY
THROUGH THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 23 12 24 15 / 50 20 20 20
INL 20 6 18 7 / 50 10 10 10
BRD 23 10 24 13 / 30 10 10 10
HYR 21 14 26 17 / 30 10 10 10
ASX 24 16 28 19 / 50 30 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
LONKA
