FXUS63 KMQT 042327 AAA
AFDMQT
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
625 PM EST FRI DEC 4 2009
UPDATED FOR 00Z TAF ISSUANCE
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN ONTARIO TO THE SRN PLAINS. FURTHER UPSTREAM...ANOTHER
STRONG SHORTWAVE TROUGH WAS MOVING SE FROM BC AND THE PAC NW.
700-300 MB QVECTOR CONV AHEAD OF A SHORTWAVE MOVING THROUGH NRN MN
SUPPORTED AN AREA OF LIGHT SNOW SHOWERS OVER NE MN INTO NRN WI.
HOWEVER DOWNSLOPE WRLY FLOW HAS HINDERED EASTWARD PROGRESS OF LOWER
CLOUDS AND FLURRIES THROUGH CNTRL UPPER MI. FAVORABLE ENVIRONMENT
FOR LES REMAINED OVER WRN LAKE SUPERIOR WITH DEEP MOISTURE...850 MB
TEHPS NEAR -14C...AND CONVERGENT WRLY FLOW. VIS IMAGERY AND WEBCAMS
INDICATED THAT THE MAIN LES BAND HAD LIFTED INTO THE NORTHERN
KEWEENAW PENINSULA...NORTH OF CALUMET AS WINDS BACKED MORE WSW AHEAD
OF THE SHORTWAVE. SNOWFALL RATES OF 2 TO 3 INCHES PER HOUR WITH THE
BAND BROUGHT A QUICK 8 INCHES OF SNOW TO CAL
&&
.SHORT TERM /TONIGHT AND SATURDAY/...
SATELLITE TRENDS AND MDLS SUGGEST THAT THE HEAVIER LES BAND WILL
AFFECT MAINLY FAR NRN HOUGHTON COUNTY AND KEWEENAW COUNTY. THE LCLY
RUN HIGH RES WRF/ARW WAS A BIT SLOWER TO MOVE THE BAND NORTHWARD AND
OFFSHORE BY SATURDAY MORNING COMPARED TO THE 12Z/18Z NAM. IN GENERAL
THE NAM HAS HAD A SLIGHTLY BETTER GRASP OF THE LOW LEVEL WIND
TRENDS. SINCE UNCERTAINTY REMAINS WITH THE WIND FIELD AND HEAVIER
SNOW SHOWERS REMAINED JUST UPSTREAM/OFFSHORE...THE LES WARNING WILL
CONTINUE OVER NRN HOUGHTON COUNTY TIL 03Z AND TIL 12Z FOR KEWEENAW
COUNTY. GIVEN EARLIER SNOWFALL RATES...ADDITIONAL AMOUNTS OF 3 TO 8
INCHES MAY BE POSSIBLE OVER KEWEENAW COUNTY.
AS THE MID LEVEL TROUGH AXIS PIVOTS SE TO UPPER MI SATURDAY...THE
ASSOCIATED SFC TROUGH SAG TO THE SOUTH WITH WINDS VEERING SHARPLY TO
THE NW TO NNW. CONVERGENCE ALONG THIS FEATURE SHOULD BRING ANOTHER
PERIOD OF HEAVIER SNOW SHOWERS INTO THE KEWEENAW SATURDAY AFTERNOON
WITH THE POTENTIAL FOR ANOTHER 2 TO 5 INCHES OF SNOW.
OTHERWISE...ONLY SCT LIGHT SNOW SHOWERS OR FLURRIES ARE EXPECTED
OVER THE REST OF UPPER MI AS THE MN SHRTWV MOVES TOWARD THE AREA.
SINCE THE FORCING IS RELATIVELY WEAK AND UPSTREAM OBS ONLY SHOWED
MAINLY FLURRIES...ONLY SLIGHT CHANCE POPS WERE MENTIONED.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
WE WILL REMAIN UNDER THE SAME PATTERN OF UPPER LEVEL LOWS DIPPING
SOUTHWARD ACROSS THE NATION THROUGH MUCH OF THIS PERIOD. THE FIRST
OF THESE...STRETCHING FROM CENTRAL UPPER MICHIGAN TO WEST CENTRAL
QUEBEC. THE TROUGH SET UP THROUGH UPPER MICHIGAN SHOULD BE EAST OF
THE CWA BY 00Z MONDAY ACCORDING TO THE 12Z ECMWF/NAM. THE 12Z GFS IS
SLIGHTLY SLOWER...WITH A WAVE STRETCHING SSW THROUGH LAKE SUPERIOR
AND NORTHERN MINNESOTA. THIS FEATURE WOULD MOVE ACROSS UPPER
MICHIGAN DURING THE DAYLIGHT HOURS MONDAY...AS A MORE AMPLIFIED
500MB RIDGE NEARS FROM THE UPPER GREAT LAKES.
STILL...WILL BE DEALING WITH THE POTENTIAL FOR A BAND OF LAKE EFFECT
SNOW SHOWERS WIGGLING ACROSS THE KEWEENAW PENINSULA TO DIP ACROSS
ONTONAGON AND NORTHERN BARAGA COUNTIES SATURDAY EVENING. HAVE
INCLUDED LIKELY POPS INITIALLY.
MODELS DO AGREE ON THIS ONE GLIMMER OF A RIDGE AT 500MB...AND NOT
JUST ZONAL FLOW...FOR THE GREAT LAKES REGION LOOKS TO COME INTO PLAY
FOR SUNDAY NIGHT AND MONDAY...AS LOW PRESSURE AT 500MB STRENGTHENS
ITS HOLD ACROSS THE PACIFIC NORTHWEST. AT THE SURFACE...HIGH
PRESSURE WILL BUILD IN FROM WESTERN AND CENTRAL CANADA SATURDAY
NIGHT THROUGH TUESDAY. MODELS STILL DO HINT AT A WEAK LOW MOVING
FROM TEXAS TO FAR LOWER MICHIGAN BY 18Z MONDAY. THE NAM IS STRONGER
AND FARTHER NORTH WITH THIS LOW...OVER NORTHERN LOWER MICHIGAN.
WHILE THE CONSENSUS IS FOR THIS SURFACE LOW TO MOVE MORE SE OF THE
CWA...I HAVE OPTED TO MINIMIZE POPS AT NO MORE THAN 30 POPS SOUTH
AND EAST.
CONTINUED THE TREND OF INCREASING POPS FOR OUR MID WEEK
SYSTEM...WITH THE SAME IDEA OF A SIGNIFICANT WINTER STORM WITH HEAVY
SNOW AND STRONG WINDS. THE 500MB TROUGH WILL BE SET UP ACROSS THE
PACIFIC NORTHWEST FOR THE END OF THE WORK WEEK WILL PUSH SOUTHWARD.
AS THE POLAR LOW DIPS INTO WEST CENTRAL CANADA TUESDAY...THE PACIFIC
NORTHWEST LOW WILL OPEN UP MONDAY NIGHT ACROSS NEAR UTAH...AND INTO
THE PLAINS STATES BY 00Z WEDNESDAY.
THE PREVIOUS FORECAST WAS DERIVED FROM THE MODELS GIVING A TRACK OF
THE SURFACE LOW FROM CHICAGO TO GEORGIAN BAY FROM 12Z WEDNESDAY TO
06Z THURSDAY. THE 12Z MODELS RUNS AT 12Z WEDNESDAY ARE A LITTLE SE
OF THE PREVIOUS THINKING...BY ABOUT 80 MILES /GFS/ TO 250 MILES
/ECMWF/. EXPECT SE WINDS TO INCREASE TUESDAY NIGHT OUT AHEAD OF THE
LOW...TO BECOME EASTERLY WEDNESDAY 12-18Z...BEFORE TURNING OUT OF
THE NORTH WEDNESDAY AFTERNOON. THE APPROACHING SURFACE HIGH WILL
NEAR FROM THE CENTRAL PLAINS...AT AROUND 1026MB. EVEN DURING THE
PERIOD OF WAA...850MB TEMPERATURES SHOULD REMAIN AT OR BELOW -10C.
AS A RESULT...A GOOD AMOUNT OF LAKE ENHANCEMENT CAN BE EXPECTED AS
THE WINDS BECOME ONSHORE FROM BOTH LAKE MICHIGAN TUESDAY NIGHT...AND
LAKE SUPERIOR ON WEDNESDAY. TOTAL SNOW AMOUNTS...OR EVEN QPF WILL
COME MORE IN LINE AS THE TIME NEARS...WITH LARGE VARIABILITY
CURRENTLY SHOWN. AROUND A QUARTER OF AN INCH OF LIQUID SEEMS PRETTY
STANDARD ACROSS MUCH OF THE CWA.
AS THE SURFACE LOW SHIFTS INTO THE LOWER GREAT LAKES AND NEW ENGLAND
STATES...THE SOUTHERN 500MB TROUGH WILL LIKELY DEEPEN OVER LAKE
HURON BY 00Z THURSDAY...AND SHIFT INTO SOUTHERN QUEBEC BY 12Z
THURSDAY...AS ZONAL FLOW SETS UP ACROSS THE NORTHERN PLAINS AND
UPPER GREAT LAKES. EXPECT SOME WIND COMPONENT OFF OF LAKE SUPERIOR
THROUGH THE END OF THE FORECAST PERIOD AS LOW LEVEL MOISTURE SLOWLY
EXITS.
&&
.AVIATION /FOR THE 00Z TAF ISSUANCE/...
CMX...EXPECT A SW FLOW OF DRY LLVL AIR TO KEEP INTENSE LES BAND TO
THE NW OF THIS SITE INTO SAT MRNG WITH THE DRY AIR ALSO CONTRIBUTING
TO PREDOMINANT VFR CONDITIONS. AS THE LLVL FLOW BEGINS TO VEER MORE
WNW WITH THE ARRIVAL OF A LO PRES TROF ON FRI AFTN...THE LES BAND WL
SINK S BACK ACRS CMX IN THE AFTN...BRINGING IFR CONDITIONS TO CMX
THEN.
SAW...DOWNSLOPE WSW WIND COMPONENT WITH LITTLE LK MOISTENING THRU
THE FCST PD WL RESULT IN PREDOMINANT VFR CONDITIONS.
&&
.MARINE... /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/
LAKE INDUCED TROUGHING/CONVERGENCE WILL LCLY BOOST WIND SPEEDS INTO
THE 20-25 KT RANGE INTO SATURDAY MORNING. OTHERWISE...WINDS THROUGH
SUN REMAIN 20 KTS OR LESS AS WEAK TROUGH DRIFTS ACROSS THE UPPER
GREAT LAKES. THERE IS THE POTENTIAL FOR A STRONG LOW PRESSURE
SYSTEM/GALE FORCE WINDS TO AFFECT MUCH OF GREAT LAKES REGION TUE AND
WED OF NEXT WEEK. SIGNIFICANT UNCERTAINTY REMAINS WITH THE EXACT
TRACK OF SYSTEM...BUT WINDS MAY END UP MUCH HIGHER THAN SHOWN IN THE
CURRENT FCST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ003.
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR MIZ001.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS/SHORT TERM...JLB
LONG TERM...KF
AVIATION...KC
MARINE...JLB
