FXUS63 KMQT 290522 AAB
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1230 AM EST SUN NOV 29 2009
.SYNOPSIS...ISSUED AT 355 PM
WV IMAGERY AND RUC ANALYSIS INDICATED MAINLY ZONAL NRN STREAM
MID/UPPER LEVEL FLOW ACROSS THE NRN CONUS. AN UPSTREAM SHORTWAVE
TROUGH EXTENDED FROM SW MANITOBA INTO NW NORTH DAKOTA. AT THE
SFC...A WEAK TROUGH EXTENDED FROM ERN UPPER MI INTO ERN WI. ONLY A
WEAK SFC TROUGH REFLECTION OVER NW MN/ERN ND WAS ASSOCIATED WITH THE
UPSTREAM SHRTWV. VIS SATELLITE LOOP SHOWED AN AREA OF LOWER CLOUDS
EXPANDING FROM NW INTO CNTRL UPPER MI AS THE 900-925 THERMAL TROUGH
MOVES IN FROM THE NW.
&&
.SHORT TERM /TONIGHT AND SUNDAY/...ISSUED AT 355 PM
MODELS WERE IN REASONABLE AGREEMENT WITH THE TIMING/STRENGTH THE
SHORTWAVE MOVING THROUGH NRN MN TONIGHT AND INTO UPPER MI SUNDAY.
PER UPSTREAM OBS AND RADAR TRENDS...THE GFS AND NAM SEEMED OVERDONE
WITH THE QPF THROUGH TODAY. HOWEVER...THE SHRTWV AND ASSOCIATED
700-300 MB QVECTOR CONV IS EXPECTED TO BE STRONG ENOUGH TO SQUEEZE
OUT SOME LIGHT PCPN INTO MUCH OF THE CWA...MAINLY BTWN 06Z-18Z/SUN.
HOWEVER...NORTH TO NORTHWEST FLOW LAKE ENHANCEMENT WITH 850 MB TEMPS
DOWN TO NEAR -6C BY 12Z/SUN AND AROUND -9C 00Z/MON. SUBTLE
DIFFERENCES IN MODEL LOW LEVEL WIND FIELDS TRANSLATES TO MORE
UNCERTAINTY WITH WHERE THE HEAVIER LES BANDS WOULD DEVELOP. THE 18Z
NAM AND LCLY RUN HIGH RES WRF/ARW COMPARED TO THE 12Z RUNS AND THE
12Z GFS SUGGEST WINDS WOULD VEER ENOUGH TO BRING MORE SNOW INTO
NORTH CNTRL UPPER MI. OVERALL SNOWFALL AMOUNTS INTO THE 1 TO 3 INCH
RANGE MAY BE POSSIBLE WHERE ANY HEAVIER LAKE ENHANCED BANDS SET UP.
ACCUMULATIONS LESS THAN AN INCH ARE EXPECTED OVER THE REST OF UPPER
MI. NMRS/LIKELY POPS STILL LOOK ON TRACK OVER THE NORTH. FOR
NOW...ONLY SLIGHT CHANCES WERE MADE TO THE PREVIOUS FCST
WHICH...MAINLY TO DELAY ONSET OF SNOW INTO WEST UPPER MI.
WET-BULB ZERO HEIGHT FCST SUGGEST POSSIBILITY A SNOW/RAIN MIX OVER
THE EAST AND SOUTH TIL THE MORE SUBSTANTIAL COLD AIR MOVES IN BY
SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...ISSUED AT 355 PM
UNSETTLED WEATHER REMAINS...WITH SNOW /MAINLY LAKE EFFECT SNOW
SHOWERS/ POSSIBLE SOMEWHERE ACROSS THE CWA MOST PERIODS THROUGH THE
START OF THE NEXT WEEKEND. TO START OUT THE FORECAST PERIOD AT 00Z
MONDAY...THE WEATHER MAP WILL LIKELY INCLUDE A SOUTHERN STREAM 500MB
CUT OFF LOW ACROSS THE NORTHERN BAJA PENINSULA. CLOSER TO HOME...THE
NORTHERN STREAM LOW WILL CONTINUE TO SPIN ACROSS SOUTHEASTERN CANADA
MAINLY EAST OF JAMES BAY...WITH A TROUGH STRETCHING ACROSS NE LAKE
SUPERIOR THROUGH NEBRASKA AND CENTRAL KANSAS. AT THE SURFACE...LOW
PRESSURE WILL BE LOCATED ACROSS THE LOWER GREAT LAKES...WITH A
STRONG RIDGE DOMINATING MUCH OF THE WESTERN HALF OF THE NATION.
THE MAIN 500MB TROUGH SHOULD BE EAST OF THE CWA BY 06Z MONDAY...WITH
THE 06Z GFS INDICATING A WEAKER WAVE PROPAGATING SOUTHEASTWARD
ACROSS UPPER MICHIGAN MONDAY AFTERNOON. THE SURFACE RIDGE WILL
ATTEMPT TO MOVE ACROSS THE CWA...BUT HAVE A DIFFICULT TIME...AS
STRONGER LOW PRESSURE DIVES A WEAK TROUGH BEGINS TO PUSH IN FROM
WEST CENTRAL CANADA. FOR MONDAY NIGHT AND TUESDAY...THE 500MB RIDGE
WILL BE MOVING OVERHEAD...AS THE SOUTHEASTERN CANADIAN LOW CONTINUES
TO SPIN AND DEEPEN SLIGHTLY...AND THE CUT OFF LOW MOVES ALONG THE
MEXICO/US BORDER TO WESTERN TEXAS. THE CANADIAN SURFACE LOW WILL
DIVE NEAR LAKE WINNIPEG BY 12Z TUESDAY. THIS SYSTEM WILL LIKELY BE A
THIRD ACROSS THE CWA BY 00Z WEDNESDAY...WITH THE LOW ITSELF LOCATED
SOMEWHERE JUST N TO NW OF LAKE SUPERIOR...AND A COLD FRONT LIKELY
STRETCHING ACROSS THE KEWEENAW PENINSULA...TO NEAR IRON
MOUNTAIN...WITH WINDS BECOMING MORE WESTERLY BEHIND THE FRONT.
THING WILL DEFINITELY START TO BECOME INTERESTING FROM TUESDAY
EVENING...WITH THE COLD FRONT/SURFACE TROUGH EAST OF THE CWA FOR
SURE BY 00Z THURSDAY. WINDS WILL BECOME MORE OUT OF A NORTHERLY
DIRECTION LATE WEDNESDAY AFTERNOON...BEFORE TURNING MORE
NORTHWESTERLY THURSDAY THROUGH THE REMAINDER OF THE FORECAST PERIOD.
EXPECT LES TO DOMINATE THOSE AREAS INFLUENCED BY WNW WINDS OFF OF
LAKE SUPERIOR. HAVE ADDED LIKELY POPS TO PORTRAY THIS BETTER
LIKELIHOOD.
MODEL WISE...THE 06Z GFS LOOKS TO BE ONE OF THE QUICKER
MODELS...WHILE THE 12Z NAM IS NOW ON THE SLOWER END OF THE
SPECTRUM...ESPECIALLY WITH THE TRACK OF THE AFOREMENTIONED LOW AND
THE EJECTING 500MB LOW FROM TEXAS. THE 12Z RUN OF THE GFS HAS SLOWED
DOWN A BIT COMPARED TO THE 06Z. ALSO TUESDAY EVENING...AT 500MB THE
RIDGE EXITS TO THE EAST AND THE NEXT NORTHERN STREAM TROUGH SWINGS
TO NORTHERN MINNESOTA...AND THE SOUTHERN STREAM LOW BEGINS TO OPEN
UP AND MERGE INTO THE STRENGTHENING TROUGH. THIS IS ALSO WHEN THE
06Z GFS BEGINS TO QUICKEN AND DEEPEN SIGNIFICANTLY WITH RESPECT TO
THE OTHER AVAILABLE SOLUTIONS. THE BLENDING OF THE SYSTEMS WILL BE
IN FULL FORCE WEDNESDAY...AS THE SOUTHERN LOW MERGES WITH OUR
NORTHERN TROUGH ACROSS ARKANSAS AND TENNESSEE. AT THE SAME
TIME...LOOK FOR MERGING NORTHERN SYSTEMS...AS THE SOUTHEASTERN
CANADIAN LOW SWINGS BACK ACROSS TO NEAR JAMES BAY. FOR UPPER
MICHIGAN THIS WILL RESULT IN SW FLOW ALOFT UNTIL THE WELL MERGED
TROUGH SLIPS ACROSS THE CWA WEDNESDAY NIGHT. THE 500MB TROUGH WILL
REMAIN ACROSS THE UPPER GREAT LAKES UNTIL AT LEAST FRIDAY NIGHT/00Z
SATURDAY. AT THIS TIME...THE ECMWF SLIDES A WEAK RIDGE ACROSS UPPER
MICHIGAN AND LAKE SUPERIOR...WITH YET ANOTHER WEAKER TROUGH SET UP
ACROSS THE NORTHERN PLAINS...EXPECTED TO MOVE TO LAKE SUPERIOR JUST
AFTER 00Z SUNDAY.
IT LOOKS LIKE THE COLD AIR WILL BE TRAPPED ACROSS THE REGION...AT
LEAST IN THE NEAR TERM. THE ECMWF PLACES THE COLDEST AIR...AROUND
-13C BY 12Z SATURDAY. THE 06Z GFS IS SLIGHTLY COLDER...RANGING FROM
-13C EAST TO -17C FAR WEST. THE COOLEST MORNING TEMPERATURE WE HAVE
HAD SO FAR AT WFO MQT IS 17 DEGREES EARLIER THIS MONTH. NORMAL LOWS
ARE IN THE UPPER TEENS. WE MAY REACH THE SINGLE DIGITS TO MID TEENS
NEXT SATURDAY...ACROSS INTERIOR WESTERN UPPER MICHIGAN...AS
TEMPERATURES BEGIN TO FALL TO AT OR JUST BELOW NORMAL VALUES FROM
THURSDAY THROUGH THE END OF THE FORECAST PERIOD.
DEALING WITH INCONSISTENT MODELS...WHILE TRYING TO KEEP A FAIRLY
CONSISTENT FORECAST...HPC WENT WITH MAINLY ENSEMBLE MEANS OF THE
ECMWF AND GEFS FOR FOR THURSDAY ON. THE OPERATIONAL 00Z/06Z GFS WERE
NOT USED DUE TO THE FASTER AND MORE INTENSE SCENARIO. THE 12Z GFS
WAS HIGHLIGHTED AS BEING MUCH MORE REALISTIC...AS WAS USED IN THE
BLEND OF THE AFTERNOON UPDATE TO THE HPC GUIDANCE...WHICH MAY BE
USED IN OUR NEXT FORECAST PACKAGE.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
MVFR CONDITIONS WILL CONTINUE WITH A SHORTWAVE AND LAKE ENHANCED
SNOW MOVING THROUGH. MAY SEE A BRIEF PERIOD OF IFR BTWN 06-09Z AT
SAW WITH SOME LAKE ENHANCED SNOW SHOWERS MOVING IN FROM THE NORTH.
MVFR WILL CONTINUE THROUGH THE REST OF THE PERIOD.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
NORTH WINDS LESS THAN 20 KT ARE EXPECTED TONIGHT AND SUNDAY AS A
TROUGH MOVES SOUTH OF THE REGION AND LOW PRESSURE DEVELOPS OVER LAKE
HURON. AS THE LOW DEEPENS AND MOVES TO THE EAST IT WILL BRING
INCREASING NORTH TO NORTHWEST WINDS OF 15 TO 25 KT BY LATE SUNDAY
INTO SUNDAY NIGHT. WINDS SHOULD REMAIN AT OR BELOW 25 KT UNTIL LATE
TUE INTO WED WHEN SOUTHWEST TO WEST GALES ARE POSSIBLE AS A STRONG
LOW PRESSURE SYSTEM MOVES FROM MANITOBA TOWARD NORTHWEST ONTARIO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS/SHORT TERM...JLB
LONG TERM...KF
AVIATION...07
MARINE...JLB
