FXUS63 KMQT 120516
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1210 AM EST SAT DEC 12 2009
UPDATED AVIATION DISCUSSION FOR 06Z TAFS
.UPDATE... /ISSUED AT 1110 PM/
LK EFFECT ON THE KEWEENAW REMAINS THE MAIN ISSUE. LATEST OBS AND
SPOTTER REPORTS OVR THE KEWEENAW INDICATE A DIMINISHING TREND TO LK
EFFECT. IR SATELLITE THAT SHOWED ENHANCEMENT/HEAVIER SNOW SHOWERS
EARLIER IN THE EVENING...SHOWED A WARMING OF CLOUD TOPS JUST BEFORE
MID CLOUDS FM THE WEST SPREAD OVERHEAD...RESTRICTING THE VIEW OF ANY
LK EFFECT. OVERALL...TEMPS AT INVERSION TOP HAVE WARMED LOOKING AT
UPSTREAM SOUNDINGS AT MPX/INL...SO BTWN THIS TREND AND WINDS ALOFT
BACKING SW...EXPECT THE SNOW SHOWERS TO DIMINISH THROUGH THE NIGHT.
CANCELLED LK EFFECT WARNING FOR NRN HOUGHTON A BIT EARLY...BUT WILL
LEAVE THE WARNING GOING FOR KEWEENAW. BASED ON ALL HIGH RESOLUTION
GUIDANCE AND CURRENT TRENDS...ENDED THE WARNING AT 4 AM EST. LOCALLY
COULD SEE AN ADDITIONAL 2 TO 4 INCHES IN KEWEENAW COUNTY...BEFORE
THE SNOW FINALLY ENDS. STRONG SW FLOW ALSO SHOULD RESULT IN LESS OF
A CHANCE OF LK EFFECT DROPPING BACK ONSHORE IN KEWEENAW COUNTY ON
SATURDAY THOUGH THERE IS SOME INDICATION THIS COULD HAPPEN IN THE
AFTN. OPTED TO KEEP A SLIGHT CHANCE POP FOR FAR NRN KEWEENAW COUNTY
ON SATURDAY.
&&
.UPDATE... /ISSUED 710 PM EST/
LK EFFECT ON THE KEWEENAW THE MAIN ISSUE. DOMINANT SNOW BAND WITH
RATES UP TO 3"/HR HAS NOW MADE IT TO THE NORTH SHORE OF KEWEENAW
COUNTY. CALL TO SHERIFF TURNED UP HEAVY SNOW/WHITE-OUT CONDITIONS IN
THE BAND. NOW...DESPITE THE WINDS BECOMING SW OVR ALL SITES ON THE
KEWEENAW...IR SATELLITE INDICATED NEW DEVELOPMENT OF STRONG LK
EFFECT SNOW SHOWER BAND AFT 5 PM EST JUST NORTH OF ONTONAGON AND
INTO THE AREAS MAINLY WEST OF HOUGHTON/HANCOCK. SPOTTER REPORT FM
HANCOCK TURNED UP OFF AND ON HEAVY SNOW IN THE VCNTY OF THE BAND.
RUC 13/NAM BOTH INDICATED SECOND SURGE OF LOW-LEVEL CONVERGENCE...
POSSIBLY BEING REALIZED IN THIS SNOW BAND. TWEAKED SNOW AMOUNTS UP
THIS EVENING IN A CORRIDOR FM REDRIDGE TO CALUMET AND SENT OUT AN
UPDATED WINTER WEATHER STATEMENT. ADDITIONAL SNOW AMOUNTS AFT 7 PM
EST COULD REACH 6 INCHES IF THE SNOW SHOWERS PERSIST. BACKING OF
WINDS TO SW ALOFT SHOULD PUSH ALL SNOW SHOWERS OUT OF HOUGHTON
COUNTY BY MIDNIGHT...SO WILL NOT EXTEND WARNING. SINCE THIS NEW
ROUND OF LK EFFECT WILL ALSO DRIFT ACROSS KEWEENAW COUNTY AFTER
MIDNIGHT...EXPECT TO LEAVE THE LK EFFECT WARNING THERE UNTIL
ORIGINAL EXPIRATION AT 12Z SAT. TWEAKED TEMPS ALL AREAS TO INDICATE
POTENTIAL FOR SLIGHTLY RISING TEMPS LATE TONIGHT AFTER PREV FCST LOW
TEMPS ARE REACHED LATE THIS EVENING INTO EARLY OVERNIGHT.
&&
.SHORT TERM... /ISSUED 405 PM EST/
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 06Z TAF ISSUANCE/...
INCREASING WARM AIR ADVECTION ALOFT ALLOWS FOR SCT/BKN MID-LVL
CLOUDS THROUGH SATURDAY EVENING. VFR CONDITIONS WILL PREVAIL FOR
BOTH TAF SITES.
&&
.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 4 AM EST SATURDAY FOR MIZ001.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 AM EST SATURDAY FOR LSZ265>267.
LAKE MICHIGAN...NONE.
&&
$$
UPDATES...JLA
SHORT TERM...VOSS
LONG TERM...JLB
AVIATION...JLA
MARINE...VOSS
