Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 290017 AAA
AFDDLH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
717 PM CDT TUE OCT 28 2014

.UPDATE...
ISSUED AT 717 PM CDT TUE OCT 28 2014

MAJOR DEEP-LAYER CYCLOGENESIS IS WELL UNDERWAY THIS EVENING TO THE
NORTHEAST OF LAKE SUPERIOR. 500 MB LOW HAS NOW TRANSLATED EAST OF
THE DLH CWA /CENTERED NEAR LAKE NIPIGON AS OF 00Z/..AND BENT-BACK
INVERTED SURFACE TROF THAT IS ASSOCIATED WITH THE TROWAL REGION OF
THIS CYCLONE IS STARTING TO COLLAPSE TO THE SOUTHEAST. IR
SATELLITE AND CANADIAN RADAR DATA IS NOW INDICATING THAT THE FAR
WESTERN EDGE OF THE LARGE SCALE DEFORMATION ZONE OVER MUCH OF
ONTARIO IS SAGGING SOUTHWARD AT AROUND 15 TO 20 MPH..AND WILL MOVE
SOUTHWARD INTO FAR NORTHERN MINNESOTA OVER THE NEXT FEW HOURS.

THERE SHOULD BE SUFFICIENT LIFT/COOLING TO SUPPORT ALL SNOW WITH
THIS PRECIP BAND AS IT AFFECTS AREAS GENERALLY EAST OF THE HIGHWAY
53 CORRIDOR. WE WILL NEED TO MONITOR THINGS RATHER CLOSELY THIS
EVENING..AS THERE IS AT LEAST SOME POTENTIAL FOR A FEW SLUSHY
INCHES OF ACCUMULATION IN A FEW PLACES DURING THE MAX INTENSITY OF
PRECIP..WHCIH SHOULD OCCUR ROUGHLY BETWEEN 8 PM AND 2 AM.

ELSEWHERE FARTHER SOUTH..THERE HAVE BEEN MANY REPORTS OF LIGHT
SNOW MIXING IN WITH THE RAIN FOR SHORT PERIODS OF TIME ACROSS THE
SW TWO-THIRDS OF THE CWA. KDLH CC/ZDR DATA SUGGESTS THAT THE
AMBIENT FREEZING LEVEL IS ONLY A FEW HUNDRED FEET AGL..AND IT
APPEARS AS THOUGH ANY SMALL SCALE ENHANCEMENT TO PRECIP RATES IS
SUFFICIENT TO RESULT IN LOCAL DIABATIC COOLING UNDERNEATH SMALL
SCALE HEAVIER SHOWERS TO ALLOW A MIX OR ALL SNOW TO REACH THE
GROUND. THIS WILL LIKELY CONTINUE FOR THE NEXT FEW HOURS AS LOBE
OF RADAR ECHOES TRANSLATES ESEWD. HOWEVER..WITH SURFACE TEMPS IN
THE MID 30S/RELATIVELY WEAK SNOWFALL RATES..AND WARM AMBIENT
GROUND TEMPS..ABOUT ALL THE ACCUMULATION THAT IS EXPECTED IN AREAS
FARTHER SOUTH IS SOME CRUSTING ON VEHICLES AND OTHER ELEVATED AND
EXPOSED SURFACES.

WE HAVE MADE SOME MINOR ADJUSTMENTS TO THE FORECAST TO REFLECT THE
MORE SNOWY SOLUTION ACROSS THE NORTH..ALONG WITH HIGHER POPS AND
SIGHTLY COLDER TEMPS.  UPDATES ARE ALREADY AVAILABLE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 329 PM CDT TUE OCT 28 2014

TONIGHT...THE LARGE SCALE CIRCULATION ASSOCIATED WITH THE DEEP
SFC/MID LVL LOW PRESSURE SYSTEM WILL KEEP A CANOPY OF LOW CLOUDS AND
PRECIP OVER THE REGION OVERNIGHT. AS MID LVL LOW MIGRATES EAST...THE
SFC TROUGH WILL DROP SOUTH FROM ONTARIO THIS EVENING. PTYPE WILL
TRANSITION TO A MIX OF RAIN/SNOW AND PERHAPS A PERIOD OF WET SNOW.
VERY TOUGH TO DETERMINE POTENTIAL AMOUNTS THIS TIME OF YEAR. THIS IS
DUE TO THE MARGINAL BDRY LYR THERMAL PROFILES AND DEPENDENCY OF
DIABATIC COOLING/SNOW PRODUCTION UPON AREAS OF ENHANCED VERTICAL
MOTION. HI-RES PTYPE OUTPUT FROM HRRR IS RATHER SLOW TO MAKE THE
TRANSITION TO FROZEN PRECIP OVERNIGHT. THE NAM12/RUC13 ARE FASTER IN
COOLING THE NEAR SFC LAYER SO CONFIDENCE IS NOT THAT GREAT. GIVEN
THAT SNOW HAS BEEN OCCURRING JUST WEST OF THE REGION DURING THE
DIURNAL WARM PERIOD...WOULD THINK THAT WITH ADVENT OF NOCTURNAL BDRY
LYR COOLING...WE SHOULD SEE THE TRANSITION OCCUR IN MOST OF NE MN
ZONES BY MID/LATE EVENING. SOME LOCATIONS MAY SEE UP TO AN INCH ON
ELEVATED DECKS OR GRASSY SURFACES. THE PROBABILISTIC PRODUCTS FROM
SREF AND NARRE-TL FAVOR THE ARROWHEAD AND THE GOGEBIC RANGE FOR
SOME ACCUMULATION. GUSTY WINDS WILL REMAIN BASED ON BUFKIT MOMENTUM
PROFILES SUPPORTED BY THE PRESENCE OF A FAIRLY LARGE SFC PRESS
GRADIENT OVER THE CWA UNTIL EARLY MORNING.

TOMORROW...GRADUAL CLEARING OCCURS FROM WEST TO EAST AS THE SFC/MID
LVL LOWS SHIFT WELL EAST OF THE REGION. ALTHOUGH DEEP LAYER DRYING
IS FCST...MAJORITY OF NWP SUGGESTS RESIDUAL MOISTURE WILL REMAIN IN
A SHALLOW LAYER NEAR 2K TO 3K FT. WILL MAINTAIN A MOSTLY CLOUDY
FCST  FOR NOW. PRECIP SHOULD EVENTUALLY DIMINISH EXCEPT OVER ERN
EDGE OF CWA.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 329 PM CDT TUE OCT 28 2014

A WEAK MID LEVEL S/W AND ASSOCIATED INVERTED SFC TROUGH WILL TRACK
EWD THROUGH THE UPPER MIDWEST WED NIGHT/THUR MORNING AND PRODUCE A
SLIGHT CHANCE OF RAIN AND/OR SNOW THROUGH THE REGION. A MORE POTENT
UPPER S/W WILL DROP IN FROM THE NORTH AND USHER IN ADDITIONAL HIGHER
CHANCES FOR RAIN SHOWERS THUR AFTERNOON...EVENTUALLY CHANGING OVER
TO ALL SNOW THUR NIGHT AND FRI MORNING. THE TRACK OF THE LOW...FROM
NRN MANITOBA SEWD THROUGH WRN ONTARIO AND INTO THE NRN GREAT LAKES
WILL ALLOW THE BULK OF THE PRECIP TO FALL ACROSS THE ERN HALF OF THE
FORECAST AREA. THE LARGE SCALE LIFT ASSOCIATED WITH THE WAVE WILL
OCCUR OVER WRN ONTARIO...CLIPPING THE ARROWHEAD AND IN THROUGH NRN
WI AND EWD INTO THE U.P. OF MICH. A SURGE OF ARCTIC AIR WILL PUSH
ACROSS THE REGION AS THE S/W MOVES THROUGH AND MODIFIES THERMAL
PROFILES ENOUGH TO CHANGE THE RAIN SHOWERS OVER TO SNOW LATE
THURSDAY...AND ESPECIALLY THUR NIGHT/FRI MORNING. COULD SEE AROUND 1
INCH OF SNOW ACCUMULATE OVER THE ARROWHEAD...WITH TRACE AMTS AROUND
THE TWIN PORTS. THE AREA EXPECTING TO SEE THE MOST WITH THIS SYSTEM
WILL BE ACROSS THE SNOW BELT REGION OF ASHLAND AND IRON COUNTIES
WHERE LAKE ENHANCEMENT WILL ALLOW A QUICK 1-2 INCHES TO FALL DURING
THE OVERNIGHT HOURS. FAVORABLE NORTH WINDS AND STEEP/MOIST BL LAPSE
RATES WILL ALL CONTRIBUTE TO SLIGHTLY HIGHER SNOW AMTS IN THIS AREA.

HIGH PRESSURE WILL BUILD IN QUICKLY FROM THE WEST ACROSS THE NRN
PLAINS AND UPPER MIDWEST DURING THE REST OF THE DAY FRIDAY AND
FURTHER EWD THROUGH THE GREAT LAKES FRI NIGHT/SAT MORNING. ON THE
BACK SIDE OF THIS HIGH...A SWLY FLOW WILL DEVELOP AND ALLOW
TEMPERATURES TO WARM THROUGH THE WEEKEND. THE RIDGE WILL AMPLIFY
ACROSS THE REGION AS THE NEXT LOW PRESSURE SYSTEM MOVES IN FROM THE
ROCKIES DURING THE DAY SUNDAY. WILL START TO SEE THE INFLUENCE FROM
THIS NEXT SYSTEM FROM THE WEST SUNDAY NIGHT WITH A SLIGHT CHANCE OF
RAIN. THE POTENTIAL FOR RAIN IS EXPECTED TO PERSIST THROUGH MONDAY.

TEMPERATURES WILL COOL SLIGHTLY EARLY IN THE PERIOD...AND THEN WARM
GRADUALLY THROUGH THE REST OF THE PERIOD. HIGHS THURSDAY WILL TOP
OUT IN THE UPPER 30S TO UPPER 40S WITH LOWS IN THE MID 20S TO LOWER
30S. HIGHS ON FRIDAY WILL DROP INTO THE 30S...WITH LOWS IN THE 20S.
TEMPERATURES WILL REBOUND SLIGHTLY INTO THE WEEKEND WITH HIGHS BACK
INTO THE 40S AND LOWS IN THE 30S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 717 PM CDT TUE OCT 28 2014

WRAP AROUND PRECIP/CLOUDS AND WEAKENING DEFORMATION ZONE BEHIND
DEPARTING CYCLONE WILL ROTATE SOUTHWARD ACROSS THE DULUTH TAF
SITES THIS EVENING..WHILE GRADUALLY WEAKENING OVERNIGHT. LIGHT
RAIN OR A RAIN/SNOW MIX WILL AFFECT KDLH/KHYR/KBRD FOR THE FIRST
4-6 HOURS OF THE FORECAST PERIOD. A MORE SUSTAINED BAND OF SNOW
WILL AFFECT KINL THROUGH 07Z..AND MAY SAG FAR ENOUGH SOUTH TO
AFFECT KHIB. PRECIP WILL GRADUALLY END 06-12Z TIME FRAME AT ALL
TAF SITES..AND WINDS WILL DIMINISH RAPIDLY AFTER 12Z AS PRESSURE
GRADIENT WEAKENS. HOWEVER..BKN-OVC MVFR CEILINGS ARE EXPECTED TO
PERSIST AT ALL TAF SITES THROUGH THE END OF THE FORECAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  33  41  33  43 /  70  20  10  20
INL  31  39  30  40 /  70  20  10  30
BRD  31  43  33  47 /  30  10  10  10
HYR  34  44  32  47 /  50  10  10  30
ASX  35  44  33  47 /  70  30  10  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 AM CDT WEDNESDAY FOR LSZ121-
     146>148.

     SMALL CRAFT ADVISORY UNTIL 4 AM CDT WEDNESDAY FOR LSZ144-145.

     SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140>143.

&&

$$

UPDATE...MILLER
SHORT TERM...CANNON
LONG TERM...HUYCK
AVIATION...MILLER






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