FXUS63 KDLH 262346 AAA
AFDDLH
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
546 PM CST THU NOV 26 2009
.AVIATION...00Z TAF ISSUANCE...
WIDESPREAD MVFR STRATUS DECK CONTINUES ACROSS ALL TERMINALS EXCEPT
KBRD. CEILINGS HAVE BEEN GRADUALLY LIFTING ACROSS WRN CWA AS
RELATIVELY DRIER AIR ADVECTS EASTWARD. HAVE CHOSEN OPTIMISTIC FCST
OF CONTINUED IMPROVEMENT OVERNIGHT AT ALL TERMINALS AS HIGH
PRESSURE MOVES INTO REGION AND SUBSIDENCE ALLOWS THINNING AND
DECREASING OF STRATUS CLOUD DECK. NEXT AREA OF CLOUDS...MID LVL
WARM ADVECTION...WILL PUSH INTO REGION DURING THIS PERIOD.
&&
.PREV DISCUSSION... /ISSUED 254 PM CST THU NOV 26 2009/
DISCUSSION...FORECAST FOCUS IN THE NEAR TERM WILL BE ON TEMPERATURES
AND SKY COVER OVERNIGHT...WITH SHORT TERM FOCUS ON APPROACHING
WAVE/COLD FRONT TO AFFECT THE REGION SATURDAY NIGHT INTO SUNDAY.
SURFACE ANALYSIS INDICATES THE CWA STILL IN BETWEEN A HIGH PRESSURE
RIDGE...NOW PUSHING EAST OF THE RED RIVER VALLEY WITH A WARM FRONT
WELL WEST IN WESTERN/CENTRAL ND...AND LOW PRESSURE NORTH OF LOWER
MICHIGAN. PRES GRADIENT HAS BEEN WEAKENING...ESPECIALLY WEST. UPPER
LEVEL RIDGE HAS BEEN FLATTENING HAS IT PUSHES TO THE EAST. CLOUD
COVER HAS REMAINED PERSISTENT ACROSS THE NORTHLAND TODAY. CAA REGIME
HAS KEPT TEMPS STEADY IN THE MID 20S NEAR KINL TO THE LOW 30S ACROSS
NW WISC. ADDITIONALLY...MID/UPPER LEVEL CLOUD HAS BEEN STREAMING
SOUTHWEST OVER THE TOP OF THE MID/UPPER LEVEL RIDGE.
LATEST WEBCAMS/SPOTTER REPORTS IN THE LAKE EFFECT SNOWBELT INDICATE
SNOW HAS ENDED OR TAPERED TO FLURRIES AT BEST...MIXED WITH SOME
LIQUID PRECIP NEAR THE LAKE WHERE SURFACE TEMPS HOVERED NEAR
FREEZING. WHILE 850 TEMPS HAVE BEEN FALLEN RESULTING IN INCREASING
LAPSE RATES..RUC 850-700 RH PROG VALUES HAVE FALLEN BELOW THE 60%
THRESHOLD FOR ACCUMULATING SNOWFALL...SO LITTLE ELSE IS EXPECTED.
ROADS STILL LOOK FAIRLY WET...AND EXPECT SLUSH TO FREEZE ON
SURFACES TONIGHT...INCLUDING HIGHWAY 2 FROM ASHLAND TO
IRONWOOD...DUE TO TEMPERATURES FALLING WELL INTO THE 20S IN NW
WISC TONIGHT.
ONTO TONIGHT...RIDGE AXIS WILL MOVE OVER THE CWA TONIGHT. RECENT
MODEL RUNS HAVE BEEN CLEARING OUT THE LOWER CLOUDS TOO QUICKLY
TODAY. LATEST MET GUIDANCE IS SOME 5-7 DEG COLDER THAN MAV GUIDANCE
FOR LOW TEMPS TONIGHT IN MANY LOCATIONS...PARTICULARLY IN THE
BORDERLAND AND ALONG THE IRON RANGE. WE HAVE TRENDED CLOSER TO
MAV/LAMP GUIDANCE AT THIS TIME GIVEN EXPECTED SLOWER CLEARING OF
CLOUDS AND INDICATIONS FROM LATEST MODEL RUNS STARTING TO KEEP LOW
SOME LEVEL MOISTURE AROUND A BIT LONGER TONIGHT. WE DO EXPECT A
WINDOW OF CLEARING/CLOUD BREAKS WHICH WILL ALLOW TEMPS TO DROP
QUICKLY FOR A SHORT TIME. EVENING SHIFT WILL NEED TO MONITOR FOR
ADDITIONAL CLEARING IN THE NORTH AND WEST WILL ALLOW TEMPS TO
TUMBLE UNDER LIGHT WINDS. UPSTREAM LOW TEMPS UNDER THE RIDGE WERE
IN THE MID TEENS.
SURFACE HIGH SHIFTS EAST QUICKLY ON FRIDAY. RETURN FLOW BEHIND THE
HIGH AND AHEAD OF A WEAK SURFACE LOW IN THE DAKOTAS UNDER A
FLATTENING UPPER RIDGE. WAA REGIME WILL ENSUE. HI RES WRF SHOWS SOME
WEAK ECHOES IN THE ARROWHEAD...BUT LITTLE MOISTURE DOWNSTAIRS TO
SUPPORT ANY PRECIP. OTHERWISE...IT WILL BE A DRY DAY WITH MID AND
UPPER CLOUDS DUE TO WEAKENING UPPER RIDGE ALLOWING PROGRESSIVE WEAK
VORT MAXES TO WORK THROUGH THE AREA. TEMPS WILL RECOVER FROM
THURSDAY WITH SOUTHERLY WINDS...EVEN SOME 40S IN THE BRAINERD LAKES
AREA.
FAIRLY QUIET FRIDAY NIGHT AND SATURDAY MORNING...BEFORE A
PROGRESSIVE SHORT WAVE CURRENTLY OFF THE BRITISH COLUMBIA ARRIVES. A
WEAK SURFACE REFLECTION WILL DRAG A COLD FRONT THROUGH THE AREA
BEGINNING SATURDAY LATE AFTERNOON THROUGH MID-DAY SUNDAY. THE BEST
FORCING MOVES DUE EAST ALONG THE BORDER SATURDAY NIGHT/EARLY
SUNDAY BEFORE SAGGING SOUTH AND EAST AND PUSHING OFF INTO NW WISC.
AT THIS TIME...SCATTERED SNOW SHOWERS WITH LITTLE ACCUMULATION
LOOK LIKE THE PRUDENT FCST FOR NOW...WITH SOME LIGHT ACCUMULATION
IN THE NE ARROWHEAD. ADDITIONALLY...LAKE EFFECT SNOW SHOWERS LOOK
TO BE FAVORABLE ON THE SOUTH SHORE WITH GOOD CAA OVER THE LAKE
LEADING TO DELTA T'S AROUND 13-15C AND 200/300 J/KG OF LAKE
INDUCED CAPE. THERE COULD BE A FEW INCHES OF ACCUMULATION IN THE
SNOW BELT SATURDAY AFTERNOON/EVENING WHEN WINDS BECOME MOST FAVORABLE.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY. IT WILL BE A COOL AND
UNSETTLED START TO THIS TIME PERIOD...AS AN H5 TROUGH MOVES
THROUGH THE WESTERN AND CENTRAL GREAT LAKES. COULD BE A FEW
FLURRIES OR SNOW SHOWERS...ESPECIALLY ALONG THE SOUTH SHORE. THERE
IS QUITE A DISCREPANCY AMONGST THE MODELS BY MONDAY WITH ECMWF
BRINGING A REINFORCING SHOT OF COLD AIR INTO THE AREA. THE GFS
BRINGS RETURN FLOW QUICKLY INTO THE AREA. HAVE USED A COMPROMISE
SOLUTION CLOSER TO THE GEM AND ECMWF. BY TUESDAY NIGHT AND
WEDNESDAY...COLD ADVECTION AND SNOW SHOWERS SHOULD BECOME
COMMONPLACE. SHOULD BE A FAIRLY COOL BUT CLOSER TO NORMAL TIME
PERIOD.
AVIATION...WIDESPREAD MVFR CLOUDS COVERED MUCH OF THE CWA AT
MIDDAY. FORECAST SOUNDINGS AND TIME HEIGHT CROSS SECTIONS ARE NOW
MUCH MORE PESSIMISTIC IN TERMS OF CLEARING OUT LOW LEVEL MOISTURE
THAN THE PREVIOUS FEW RUNS. STILL THINK THERE WILL BE SOME DECENT
BREAKS DEVELOPING IN SOME SPOTS...BUT OVERALL THINK MVFR WILL BE THE
RULE THIS AFTERNOON. COULD BE SOME LOWERING OF CIG HEIGHTS AGAIN
DURING THE EVENING...WITH LOW CLOUDS PROBABLY BREAKING UP A FAIR
AMOUNT ON FRIDAY. THE LOW CLOUDS WILL LIKELY BE REPLACED BY MID
CLOUDS FRIDAY MORNING.
&&
.POINT TEMPS/POPS...
DLH 22 37 26 38 / 10 0 10 10
INL 15 37 24 34 / 0 10 10 10
BRD 22 43 26 41 / 0 0 10 10
HYR 19 40 21 42 / 0 0 10 10
ASX 23 40 23 43 / 10 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
CANNON/CANNON/CANNON
