FXUS63 KMQT 112104
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
405 PM EST FRI DEC 11 2009
.SHORT TERM...
CONCERNS TONIGHT WILL FOCUS ON WSW HEADLINES FOR NRN HOUGHTON AND
KEWEENAW COUNTIES.
SFC WINDS ALREADY BEGINNING TO BACK FROM W TO SW IN RESPONSE TO
APPROACHING RDG AXIS OVER MN AND WRN WI. THE BACKING WINDS OVER LAND
AND CONTINUED WRLY WINDS OVER LAKE SUPERIOR HAVE PRODUCED A
CONVERGENT DOMINANT LES BAND OVER WRN LAKE SUPERIOR IN THE LAST FEW
HRS. THIS DOMINANT BAND HAS PASSED FROM NRN HOUGHTON INTO KEWEENAW
COUNTY IN THE PAST HR. MOHAWK REPORTED 2-3 IN/HR RATES FM THIS BAND
IN THE PAST HR. LOOK FOR CONTINUED BACKING OF WINDS TO THE S-SW LATE
THIS EVENING AS SFC RDG AXIS PASSES EAST. THESE BACKING WINDS SHOULD
HELP PUSH ANY REMAINING LAKE EFFECT SNOW BANDS OVER THE KEWEENAW OUT
OVER LAKE SUPERIOR BY MIDNIGHT OR SHORTLY THEREAFTER. AS FOR WSW
HEADLINES...DECIDED TO SHORTEN EFFECTIVE TIME FOR NRN HOUGHTON
WARNING TO 04Z THIS EVENING GIVEN LES BANDS SHOULD SHIFT NORTH BY
THAT TIME. KEPT WARNING GOING FOR KEWEENAW COUNTY UNTIL 12Z FOR NOW
AS LES COULD LAST A BIT LONGER ALONG THE TIP OF THE COUNTY BUT WOULD
NOT SURPRISED IF THE WARNING THERE COULD ALSO BE DROPPED AROUND
MIDNIGHT. WAA AHEAD OF SHORTWAVE AND ASSOC SFC TROF OVER THE NRN
PLAINS WILL ALSO DIMINISH THE STRENGTH OF ANY REMAINING BANDS AFTER
MIDNIGHT AS 850 MB TEMPS RISE FM -20C AT 00Z THIS EVENING TO AROUND
-10C BY 12Z SATURDAY.
EXPECT A BIT MORE WIND TONIGHT AS SW GRADIENT TIGHTENS AHEAD OF
APPROACHING TROF BUT THIS WILL ALSO ALLOW FOR MORE MIXING TO HELP
KEEP MIN TEMPS FROM FALLING MUCH TONIGHT. THUS... EXPECT WIND CHILLS
TO STAY ABOVE THE ADVISORY CRITERIA TONIGHT. GENERALLY FOLLOWED MAV
GUIDANCE FOR MIN TEMPS TONIGHT WITH THE COLDEST READINGS ALONG THE
WI BDR (AROUND -5F) TO THE SINGLE DIGITS ABV ZERO FOR DOWNSLOPING
AREAS ALONG LAKE SUPERIOR AND AREAS DOWNWIND OF LAKE MI IN SW FLOW.
EXPECT ATTENDANT DRY AMS TO KEEP CONDITIONS DRY ACROSS MUCH OF THE
CWA ON SATURDAY DESPITE WAA. NAM HINTS THAT CONVERGENT LES BAND
COULD FORM NORTH OF THE KEWEENAW AND PERHAPS MOVE SOUTH OVER THE TIP
OF THE KEWEENAW ON SATURDAY. KEPT IN SOME SLIGHT CHC POPS OVER THE
KEWEENAW TO COVER THIS POSSIBILITY AND ALSO PUT IN SOME SLIGHT CHC
POPS OVER SRN SCHOOLCRAFT AND THE GARDEN PENINSULA IN CASE BACKING
WINDS COULD PUSH SOME LIGHT LES INTO THESE AREAS. HOWEVER EXPECT
LES WILL BE LIMITED BY WARMING AIRMASS.
&&
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
SATURDAY NIGHT INTO SUNDAY...A WEAK TROUGH WILL MOVE THROUGH THE
REGION WITH A BROAD AREA OF ISENTROPIC LIFT. THE GREATEST MOISTURE
AND CLOSER PROXIMITY TO THE SHORTWAVE MOVING OUT OF THE PLAINS WILL
BE MAINLY SOUTH AND EAST OF THE CWA. EXPECT SOME LIGHT SNOW COULD
BRUSH THE SERN PORTIONS OF THE CWA. THE NAM FCST SOUNDINGS...WITH A
MORE PRONOUNCED DRY LAYER ABOVE THE SHALLOW MOIST LOW
LEVELS...SUGGEST THE POTENTIAL FOR SOME FZDZ. FOR NOW...NO MENTION
BUT MAY BE NEEDED IF THAT SCENARIO HOLDS UP IN LATER MODEL RUNS.
SUNDAY NIGHT INTO TUE...THE 12Z GFS TRENDED STRONGER WITH THE
SHORTWAVE EMERGING FROM THE PLAINS INTO THE WRN GREAT LAKES WITH A
STRONGER SFC LOW FARTHER TO THE NORTH. THE GFS WAS SUPPORTED BY THE
CMC BUT THE ECMWF AND MOST GFS ENSEMBLE MEMBERS WERE WEAKER AND
FARTHER TO THE SOUTH. EITHER SCENARIO WOULD BRING LIGHT SNOW FOR
MOST OF THE AREA. UNCERTAINTY WAS MAINLY REGARDING THE EVOLUTION OF
THE LOW LEVEL WIND FIELDS AND POTENTIAL FOR LAKE ENHANCED SNOW NEAR
LAKE SUPERIOR. GOING WITH A COMPROMISE BTWN THE GFS/ECMWF WOULD
ALLOW FOR A PERIOD OF E OR NE WINDS BACKING QUICKLY TO THE NW MON
EVENING. WITH 850 MB TEMPS NEAR -10C...SEVERAL INCHES OF ADDITIONAL
SNOW MAY BE POSSIBLE NORTH BUT WITH THE QUICK SHIFT IN WIND
DIRECTION AND RELATIVELY SHALLOW DEPTH OF THE ONSHORE WINDS...NOT
CONFIDENT AT THIS POINT FOR ANY HEAVY AMOUNTS. 850 MB TEMPS DROPPING
TO AROUND -14C TO -17C BY 12Z TUE AND TO NEAR -20C BY 00Z/WED WITH
DEEP MOISTURE AVBL AS THE MID LEVEL TROUGH MOVES IN WILL LIKELY
SUPPORT HEAVY LAKE EFFECT SNOW FOR LOCATIONS FAVORED BY NW FLOW
LATER MONDAY NIGHT THROUGH TUE. SO...WILL HIGHLIGHT LES HEADLINE
POTENTIAL IN THE HWO.
WED-FRI...EXPECT NW TO WRLY FLOW LES TO CONTINUE INTO THU WITH COLD
AIR REMAINING OVER THE GREAT LAKES. THE ECMWF CONTINUES TO BE FASTER
IN LIFTING MOVING THE MID LEVEL TROUGH AND COLD AIR TO THE EAST
COMPARED TO THE GFS/GFS ENS MEAN. CONFIDENCE IN LES POTENTIAL
ALSO IS LOWER WITH POSSIBLE WIND SHIFTS AS NW FLOW SHORTWAVES MOVE
THROUGH THE REGION. CANNOT RULE OUT SOME MORE WIDESPREAD LIGHT
CLIPPER SNOW...PER 12Z GFS...BY THU NIGHT AND ADDITIONAL LES IN ITS
WAKE...BUT AGAIN PLENTY OF UNCERTAINTY WITH THESE DETAILS.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
EXPECT LIFR/IFR CONDITIONS AT KCMX TO IMPROVE TO MVFR BY AROUND 20Z
AND THEN TO VFR AFTER SUNSET AS BACKING WINDS PUSH LAKE EFFECT SNOW
BANDS NORTH OF THE AREA. VFR CONDITIONS WILL CONTINUE AT KSAW
THROUGH THE FCST PD. INCREASING WAA WILL ALLOW SOME MID-LVL CLOUDS
TO SPREAD INTO BOTH TAF SITES LATE THIS EVENING/OVERNIGHT.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
WEST GALES WILL CONTINUE THROUGH THIS EVENING OVER THE EASTERN HALF
OF LAKE SUPERIOR ON THE SOUTHERN FLANK OF LAKE SUPERIOR INDUCED LOW
PRESSURE TROUGH. ELSEWHERE...WINDS TO 30 KTS ALONG WITH FREEZING
SPRAY WILL PERSIST INTO SAT MORNING. WINDS WILL THEN REMAIN BELOW 25
KTS FROM SAT AFTERNOON INTO MONDAY. STRONGER N-NW WINDS TO 30 KTS
WILL ARRIVE MON NIGHT INTO TUESDAY AS MORE ARCTIC AIR FLOODS ACROSS
THE AREA IN THE WAKE OF ANOTHER LOW PRES SYSTEM MOVING THROUGH THE
GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING FOR MIZ003.
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR MIZ001.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 AM EST SATURDAY FOR LSZ265>267.
LAKE MICHIGAN...NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...JLB
AVIATION...VOSS
MARINE...VOSS
