FXUS63 KMQT 291734
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1225 PM EST SUN NOV 29 2009

.SYNOPSIS...ISSUED AT 346 AM
WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER YUMA, AZ WITH 
A TROUGH STRETCHING NORTHEAST ACROSS THE NORTHERN PLAINS...WESTERN 
ONTARIO TO A LOW OVER JAMES BAY. A RIDGE IS TRACKING THROUGH THE 
CANADIAN PRAIRIES. WEAK SHORTWAVE MOVING THROUGH THESE TWO SYSTEM 
ARE JUST NORTHWEST OF LAKE SUPERIOR...OVER THE DAKOTAS AND SOUTHERN 
SASKATCHEWAN...AND OVER NORTHERN MANITOBA. SURFACE ANALYSIS DEPICTS 
A LOW OVER CENTRAL LOWER MICHIGAN WITH AN ACCOMPANYING COLD FRONT 
DRAPED SOUTHWEST TO NORTH CENTRAL TEXAS. A RIDGE IS PUSHING OUT OF 
THE NORTHERN ROCKIES INTO THE NORTH HIGH PLAINS. RADAR MOSAIC 
SHOWING RAIN/SNOW SHOWERS OVER CENTRAL MINNESOTA IN ASSOCIATION WITH 
THE NORTHERN PLAINS TROUGH. 00Z RAOBS SHOWING A STRONG INVERSION 
AROUND 875MB...AND FAIRLY DRY ABOVE AND ONLY LIMITED MOISTURE BELOW.

&&

.DISCUSSION...ISSUED AT 346 PM
MODELS ARE IN FAIRLY GOOD AGREEMENT WITH TIMING AND STRENGTHS OF 
SIGNIFICANT SYSTEMS OVER THE NORTHERN PLAINS AND THE GREAT LAKES 
INTO EARLY TUESDAY. FROM TUESDAY AFTERNOON AND LATE FAVORED GOING 
WITH A GFS/ECMWF COMPROMISE. 

THE TROUGH OVER WESTERN ONTARIO WILL SWEEP INTO THE FORECAST AREA 
TODAY. THE SURFACE LOW WILL TRACK TO THE LOWER GREAT LAKES PULLING 
THE COLD FRONT INTO THE EASTERN OHIO RIVER VALLEY. THE SURFACE HIGH 
WILL SETTLE OUT OF THE HIGH PLAINS INTO THE CENTRAL AND NORTHERN 
PLAINS. TOGETHER THESE WILL MAINTAIN A NORTHWESTERLY FLOW ACROSS THE 
UPPER GREAT LAKES REGION. THE NORTHERLY FLOW HAS SET UP AN 850MB 
THERMAL TROUGH SOME DISTANCE BEHIND THE FRONT WHICH WILL STRETCH 
FROM CENTRAL ONTARIO THROUGH NORTHERN MINNESOTA INTO THE CENTRAL 
PLAINS. THIS TROUGH WILL SHIFT OVER THE FORECAST AREA THIS AFTERNOON 
PRODUCING A LAKE-850MB DELTA-T OF 14C. AN ACCOMPANYING 500MB THERMAL 
TROUGH WILL LOWER THE MID LEVELS TO -32C TOO ENHANCING THE LAPSE 
RATES. THIS WITH THE Q-VECTOR CONVERGENCE ASSOCIATED WITH THE MID 
LEVEL TROUGH WILL BE ENOUGH TO PRODUCE SNOW SHOWERS ACROSS THE AREA 
TODAY. THE LIMITING FACTOR WILL THE AVAILABLE MOISTURE. THUS LOOKING 
FOR ONLY 1 TO 2 INCHES OF SNOW OVER THE NORTHERN TIER OF THE 
FORECAST AREA TODAY. CLOUD COVER WILL LIMIT HEATING AS WELL...SO 
WILL ONLY EXPECT TO SEE TEMPERATURES INTO THE 30S TODAY. DUE THE 
LOCATION OF THE THERMAL TROUGH...THE WEST WILL SEE THE COOLEST 
TEMPERATURES AND PEAK OUT DURING EARLY AFTERNOON.

THE MID LEVEL TROUGH WILL SWEEP INTO THE LOWER GREAT LAKES TONIGHT. 
THE MANITOBA SHORTWAVE WILL MOVE INTO EASTERN MINNESOTA AS ANOTHER 
DEEP SHORTWAVE FOLLOWS INTO SOUTHERN MANITOBA. THE LOWER GREAT LAKES 
LOW WILL TRACK INTO WESTERN NEW ENGLAND AS ANOTHER WEAK LOW STARTS 
TO DEVELOP OVER WESTERN ONTARIO. THE FLOW WILL CONTINUE TO BE OUT OF 
CENTRAL CANADA ACROSS LAKE SUPERIOR. THE 850MB THERMAL TROUGH WILL 
REACH LAKE HURON TONIGHT CAUSING THE 850MB TEMPERATURES TO WARM TO 
-8C...WHICH WILL NOT ENOUGH TO SHUTOFF THE LES. THE 500MB THERMAL 
TROUGH WILL REMAIN OVER THE AREA WITH TEMPERATURES AROUND -34C. THUS 
WILL KEEP SNOW SHOWERS GOING OVER THE AREA  WITH THE MOST LIKELY 
CHANCES OVER THE COUNTIES OF CWA FAVORED WITH A NORTHWEST FLOW. COLD 
AIR ADVECTION WILL ALSO FAVOR TEMPERATURES CLOSER TO SEASONAL 
OVERNIGHT LOWS. 

THE MID LEVEL TROUGH OVER MINNESOTA WILL SWEEP INTO THE WESTERN U.P. 
ON MONDAY. DUE TO THE CIRCULATION AROUND THE JAMES BAY LOW WHICH 
WILL DEEPEN A FEW METERS. THE RIDGE OVER CANADIAN PRAIRIES WILL BE 
MORE FOCUSED OVER SASKATCHEWAN. THE SURFACE LOW WILL SETTLE OUT OF 
WESTERN ONTARIO INTO EASTERN LAKE SUPERIOR. MEANWHILE...ANOTHER 
SURFACE LOW WILL DEVELOP OVER WESTERN SASKATCHEWAN. THE APPROACH OF 
THE LOW WILL CAUSE THE WINDS TO BACK WEST. DELTA-T'S...500MB THERMAL 
TROUGH...AND THE Q-VECTOR CONVERGENCES WILL COMBINE TO KEEP LES 
GOING MAINLY OVER THE AREAS FAVORED BY A WEST WIND. THE SHORTWAVE 
WILL ALSO PRODUCE MORE OF A CHANCE OF SNOW SHOWERS OVER THE SOUTHERN 
U.P. AS WELL. 

THE MID LEVEL LOW OVER JAMES BAY WILL SLIP INTO WEST CENTRAL QUEBEC 
ON MONDAY NIGHT. THE SHORTWAVE SWINGING THROUGH THE BASE OF THE LOW 
WILL MOVE OUT OF THE FORECAST AREA AS THE MID LEVEL RIDGE BUILDS 
OVER WESTERN ONTARIO. THE SURFACE LOW WILL MOVE INTO SOUTHERN 
MANITOBA BRINGING AN ASSOCIATED FRONTAL SYSTEM INTO THE DAKOTAS. THE 
WINDS WILL REMAIN OUT OF THE WEST OVER WESTERN LAKE SUPERIOR...AND 
VEER MORE NORTHWEST OVER THE EASTERN LAKE. THE AIR MASS REMAINS 
RELATIVELY DRY. HOWEVER...DELTA-T'S WILL FAVOR LES OVER THE KEWEENAW 
PENINSULA AND EASTERN U.P. THE EASTERN U.P. WILL ALSO BE AFFECTED BY 
A LITTLE MORE FETCH AND HIGHER DELTA-T'S SO THE CHANCE OF LES WILL 
BE GREATER THERE.

THE MID LEVEL RIDGE WILL WEAKEN AS IT TRACKS ACROSS THE FORECAST 
AREA ON TUESDAY. THE MID LEVEL LOW WILL DEEPEN AS IT PUSHES INTO 
EXTREME WEST CENTRAL ONTARIO. THE SURFACE REFLECTED LOW WILL ALSO 
MOVE INTO ONTARIO WITH THE COLD FRONT EDGING INTO WESTERN LAKE 
SUPERIOR. ISENTROPIC ASCENT SHOULD CONTRIBUTE TO PRECIPITATION 
DEVELOPMENT. THE TEMPERATURES WILL BE WARM ENOUGH TO HAVE SOME MIXED 
PRECIPITATION. THE AIR MASS WILL REMAIN FAIRLY DRY SO EXPECT ONLY A 
SLIGHT CHANCE ACROSS THE AREA. 

THE MID LEVEL LOW WILL CONTINUE TO TRACK EAST ON TUESDAY NIGHT AS 
THE LONGWAVE TROUGH EXTEND WEST ACROSS ONTARIO. THE SURFACE LOW 
WILL TRACK ACROSS LAKE SUPERIOR AND THE U.P. DRAGGING THE COLD FRONT 
THROUGH THE AREA. THE AIR MASS WILL CONTINUE TO BE FAIRLY DRY. AN 
850MB THERMAL RIDGE WILL SHIFT ACROSS THE AREA AND DELTA-T'S WILL BE 
ONLY 4C - 6C. THE WINDS WILL BE FROM THE SOUTHWEST VEERING WEST 
OVERNIGHT AND INCREASING. THIS WILL ALSO LIMIT FETCH TIME. THE SNOWS 
THAT WILL OCCUR WILL BE LIMITED TO THE AREAS WITH THE GREATEST 
Q-VECTOR CONVERGENCE AS LES WILL BE VERY LIMITED. 

THE LONGWAVE TROUGH WILL CONTINUE TO DEEPEN ACROSS ONTARIO ON 
WEDNESDAY WHILE WEAK SHORTWAVES ARE EJECTED OUT OF THE BASE OF THIS 
LOW AND ACROSS THE FORECAST AREA. THE SURFACE LOW WILL LIFT 
NORTHEAST INTO QUEBEC WHILE THE ACCOMPANYING COLD FRONT IS PUSHED 
ACROSS THE OHIO RIVER VALLEY. ANOTHER 850MB THERMAL TROUGH 
ACCOMPANYING THE LONGWAVE TROUGH WILL SETTLE OVER WESTERN 
ONTARIO...PRODUCING A DELTA-T OVER LAKE SUPERIOR AROUND 14C. THE 
RESULTANT LOW LEVEL LAPSE RATE WILL PROVIDE SUPPORT OF LES 
ENHANCEMENT. 

&&

.AVIATION /FOR THE 18Z TAF ISSUANCE/...

THE BULK OF MOISTURE HAS EXITED THE AREA TO THE EAST...WITH WIND 
DIRECTION BECOMING CRITICAL...AS OUR NEXT WAVE OF MOISTURE SWINGS IN 
FROM ONTARIO. EARLY CONVERGENT NORTHERLY FLOW AT SAW WILL ALLOW VIS 
AND CEILINGS TO LOWER BRIEFLY THROUGH 20Z OTHERWISE...EXPECT 
CONDITIONS AT SAW TO IMPROVE THIS EVENING AS THE WEAK RIDGE BUILDS 
ACROSS THE REGION ALTHOUGH SNOW COULD CONTINUE AT CMX THROUGH THE 
NIGHT WITH FLOW TURNING W-NW BY MORNING.

&&

.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...

A WEAK SURFACE LOW OVER THE MID MS VLY WILL MOVE INTO THE GREAT 
LAKES TODAY INTO TONIGHT. THE LOW WILL STRENGTHEN SLIGHTLY AND WILL 
LIKELY CAUSE NLY WINDS TO INCREASE TO 15-25 KT ESPECIALLY ACROSS THE 
EAST HALF TODAY. WINDS WILL THEN BACK AHEAD OF AN ALBERTA CLIPPER 
TYPE LOW/TROUGH LATER TONIGHT INTO MONDAY. WILL KEEP WESTERLY WINDS 
OF 15-25 KT FOR LATER MONDAY INTO MONDAY NIGHT. WEAK RIDGING WILL 
BUILD ACROSS THE LAKE ON TUESDAY BEFORE THE BIG SYSTEM FOR THE WEEK 
MOVES OUT OF THE CANADIAN PRAIRIES AND INTO THE NORTHERN LAKES 
WEDNESDAY. EXPECT SOUTHERLY WINDS TO INCREASE LATE TUESDAY INTO 
TUESDAY NIGHT THEN QUICKLY VEER TO THE WEST ON TUE NIGHT AS THE COLD 
FRONT PASSES OVER. THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN 
SHOWING WESTERLY GALES BEHIND THE SYSTEM TUE NIGHT INTO WED...THEN 
SHIFTING TO THE NW BEHIND THE SECONDARY TROUGH. 

&&

.MQT WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS/DISCUSSION...DLG
AVIATION...KF
MARINE...MRD