FXUS63 KMQT 242327
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
630 PM EST THU DEC 24 2009
ISSUED FOR 00Z TAFS
.SHORT TERM (TONIGHT/FRI)...
HAS BEEN A CHALLENGING DAY...AND FCST REMAINS CHALLENGING RIGHT THRU
XMAS DAY. OVERALL...CONFIDENCE IN DETAILS IS MUCH LOWER THAN NORMAL
FOR FIRST 2 PERIODS OF FCST. DUE TO TIME CONSTRAINTS...FOLLOWING
SHORT TERM DISCUSSION WILL BE VERY GENERAL. LEAD SHORTWAVE AND
RIBBON OF STRONG ISENTROPIC ASCENT BROUGHT A BAND OF MDT/HEAVY SNOW
ACROSS WRN UPPER MI THIS MORNING INTO EARLY AFTN WITH RATES OF
1-2IN/HR. SINCE SNOW ACCUMULATIONS WERE APPROACHING WARNING
CRITERIA...WARNINGS WERE ISSUED EARLIER TODAY TO INCLUDE
GOGEBIC/ONTONAGON/HOUGHTON/KEWEENAW.
PCPN INTENSITY HAS DIMINISHED OVER THE LAST FEW HRS IN THE WAKE OF
SHORTWAVE...BUT ANOTHER SHORTWAVE IS LIFTING N TOWARD THE UPPER
LAKES. THIS WILL BRING A RESURGENCE OF PCPN INTO UPPER MI TONIGHT...
AGAIN MAINLY FOCUSED ON THE W HALF OF THE FCST AREA. THERMAL
PROFILES HAVE BEEN TOUGH TO GET A HANDLE ON. MODELS SHOW THE IMPACT
OF STRONGER VERTICAL MOTION AND RESULTING COOLING WHICH CAUSES TEMP
PROFILES TO FLUCTUATE. WHEN PCPN DIMINISHES...PROFILES WARM...
FAVORING PTYPE TO BECOME MORE LIQUID. ARRIVAL OF STRONGER VERTICAL
MOTION COOLS PROFILE TO FAVOR MORE SNOW/SLEET. GIVEN THE UNCERTAINTY
IN HOW WELL THE MODELS CAN CAPTURE THIS...INCLUDED MOST PTYPES
ACROSS THE FCST AREA WITH TENDENCY FOR MORE SNOW OVER THE W AND MORE
RAIN OVER THE E.
DEPENDING ON HOW THE STORM SYSTEM WRAPS UP TO THE SW...PCPN MAY WIND
DOWN FOR A WHILE LATE TONIGHT OR FRI MORNING IF WINDS BACK ENOUGH TO
ALLOW DRIER AIR TO AGAIN MAKE INROADS INTO UPPER MI. MODELS ARE THEN
IN DECENT AGREEMENT SHOWING PCPN INCREASING AGAIN FRI AFTN AS MAIN
ENERGY NOW OVER THE LWR MISSISSIPPI VALLEY WRAPS INTO THE UPPER
MIDWEST. COOLING ASSOCIATED WITH ASCENT SHOULD BRING A TRANSITION
BACK TO SNOW FROM SW TO NE ACROSS THE AREA FRI AFTN/NIGHT.
.LONGER TERM AFTER 00Z SAT...
NAM AND GFS SHOW 850-500 MB Q-VECTOR CONVERGENCE THROUGH SAT WITH A
DRY SLOT MOVING IN ON SAT WITH THE UPPER LEVEL 500 MB CLOSED LOW
SLOWLY MEANDERING ACROSS THE GREAT LAKES REGION THROUGH THE WEEKEND
AND THE SYSTEM ITSELF WEAKENING. MIXED PCPN FOR FRI NIGHT WILL BE
OVER THE EAST HALF OF THE CWA IN THE EVENING...BEFORE COLD AIR COMES
IN FROM THE SOUTH AFTER MIDNIGHT AND SWITCHES THE PCPN OVER TO ALL
SNOW. THERE COULD STILL BE UP TO 4 INCHES OF SNOW FRI NIGHT WITH THE
HEAVIEST OVER THE FAR SOUTH DUE TO A LAKE MICHIGAN CONTRIBUTION WITH
A SOUTHEAST WIND AND TEMPERATURES COOLING DOWN TO LAKE ENHANCEMENT
OF SNOW LEVELS. THE ADVISORIES ESPECIALLY FOR MENOMINEE AND MAYBE
DICKINSON COUNTIES MIGHT NEED TO BE EXTENDED THROUGH FRI NIGHT AND
WILL PASS THIS CONCERN ON TO THE NEXT SHIFTS TO TAKE A LOOK AT SNOW
AMOUNTS FRI NIGHT WITH THE WEAKENING STORM. FOR SAT...LAKE MICHIGAN
ENHANCEMENT OF SNOW COMES INTO PLAY WITH A SOUTH TO SOUTHEAST
WIND...BUT 850 MB TEMPERATURES ARE MARGINAL FOR SIGNIFICANT LAKE
ENHANCEMENT AT AROUND -8C TO -10C OR SO. COULD SEE UP TO 2 TO 3
INCHES OF SNOW SAT AND SAT NIGHT NEAR LAKE MICHIGAN WITH THIS EVENT.
WINDS GO NORTHERLY FOR SUN AND SHOULD SHUT OFF THE LAKE MICHIGAN
CONTRIBUTION THEN AND LAKE SUPERIOR THEN COMES INTO PLAY.
OVERALL...SEE A LIGHT SNOW EVENT CONTINUING FOR THIS WHOLE FORECAST
PERIOD FROM FRI NIGHT THROUGH SUN WITH TEMPERATURES COOLING A BIT.
IN THE EXTENDED...FOLLOWED THE 00Z ECMWF FOR THIS FORECAST AGAIN AS
IT HAS DONE WELL IN THE EXTENDED AS OF LATE. LAKE EFFECT CONTINUES
IN THIS PERIOD AS A REINFORCING SHOT OF COLD AIR COMES IN ON MON
WITH 850 MB TEMPERATURES OFF THE 00Z ECMWF DIPPING DOWN TO -14C TO
-19C OVER THE EAST AND WITH LAKE TEMPERATURES OFF LAKE SUPERIOR OF
4C...THIS IS VERY HIGH LAKE-850 DELTA-T DIFFERENCES WHICH COULD LEAD
TO A SIGNIFICANT LAKE EFFECT SNOW EVENT. WITH THE COLD AIR COMING
IN...DROPPED TEMPERATURES A BIT FOR MON AND TUE AND RAISED LOWS
SUNDAY NIGHT OUT AHEAD OF THE COLD FRONT. TEMPERATURES WILL SLOWLY
MODIFY FOR TUE THROUGH THU THEN WITH ANOTHER COLD FRONT COMING IN ON
THU. LAKE EFFECT SNOW FROM LAKE MICHIGAN COMES INTO PLAY ON WED AND
WED NIGHT WITH SOUTH WINDS AND COLD ENOUGH 850 MB TEMPERATURES TO
INTRODUCE LOW CHANCE POPS OVER THE ERN CWA. FOR THU...WEAK SYSTEM
COMES THROUGH AND PUT IN LOW CHANCE POPS EVERYWHERE. TEMPERATURES
LOOK TO BE SLIGHTLY BELOW NORMAL.
.AVIATION.../FOR THE 00Z TAF ISSUANCE/...
CHALLENGING FORECAST NEXT 24 HOURS. HIGH CONFIDENCE THAT CIGS WILL
BE IN IFR RANGE AT BOTH CMX AND SAW THROUGH THE PERIOD. CIGS MAY
EVEN FALL TO LIFR RANGE DURING THE DAY ON FRIDAY WITH VSBY
RESTRICTIONS IN FOG POSSIBLY LIFR AS WELL. PRECIPITATION WILL BE
INTERMITTENT NEXT 24 HOURS WITH PRECIP TYPE DIFFICULT TO PIN DOWN.
AS POCKETS OF VERTICAL MOTION MOVE THROUGH OVERNIGHT EXPECT MOST
PRECIP TO BE IN THE FORM OF -SN...HOWEVER WHEN LULLS ARE OCCURRING
EXPECT SOME -FZDZ. BY FRIDAY MORNING...EXPECT ENOUGH WARMING TO
RESULT IN LIQUID RAIN MIXED WITH SNOW AT BOTH LOCATIONS. EASTERLY
WINDS WILL BE QUITE GUSTY...PERHAPS GUSTING UP TO 30 KTS AT CMX.
&&
.MARINE...
BUSY WITH WINTER WEATHER.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ FRIDAY FOR
MIZ001>003-009-010-084.
WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ FRIDAY FOR
MIZ004-005-011-012.
LAKE SUPERIOR...
GALE WARNING FROM 10 PM THIS EVENING TO 5 AM EST SATURDAY FOR
LSZ264>267.
GALE WARNING FROM 5 AM TO 11 PM EST FRIDAY FOR LSZ244-245-250-
251.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ SATURDAY FOR LSZ162-263.
LAKE MICHIGAN...
GALE WARNING UNTIL 11 PM EST FRIDAY FOR LMZ221-248-250.
&&
$$
LONG TERM...07
AVIATION...MZ
MARINE...
SHORT TERM...ROLFSON
