Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 231602
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1002 AM CST SUN NOV 23 2014

.UPDATE...
ISSUED AT 1001 AM CST SUN NOV 23 2014

UPDATED TO INCREASE MAX TEMPS IN NW WI AS THEY ARE ALREADY AT THE
PREVIOUSLY FORECASTED HIGHS. ALSO MADE MINOR CHANGES TO WINDS AND
POPS BASED ON CURRENT TRENDS. WILL KEEP DENSE FOG ADVISORY IN
EFFECT THROUGH 18Z SINCE THERE IS WIDESPREAD DENSE FOG IN THE REGION.



UPDATE ISSUED AT 534 AM CST SUN NOV 23 2014

UPDATED AVIATION DISCUSSION BELOW FOR 12Z TAF ISSUANCE.

&&

.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 324 AM CST SUN NOV 23 2014

THERE REMAINS PLENTY OF CHALLENGES IN THE SHORT TERM...SPECIFICALLY
IN REGARDS TO SNOW AMOUNTS LATE TONIGHT INTO MONDAY.

THE 00Z MODEL SUITE FEATURED GFS/ECMWF SOLUTIONS THERE WERE IN
GENERAL AGREEMENT...THEN THE NAM/GEM WHICH WERE SLOWER WITH THE
LOW PRESSURE SYSTEM AND SUGGESTED HIGHER SNOWFALL OVER OUR FAR
EASTERN CWA INCLUDING NORTHWEST WISCONSIN. WE USED A BLEND AS WE
COULD NOT DISCOUNT THE SLOWER SOLUTIONS. A QUICK LOOK AT THE 06Z
NAM DOES SHOW THE LOW MOVING THROUGH A BIT FASTER.

A SOUTHERN STREAM WAVE MOVING THROUGH TEXAS AND NORTHERN STREAM WAVES
SEEN OVER THE NORTHERN PLAINS AND ANOTHER IN THE 4 CORNERS AREA WILL
ALL COMBINE TO CAUSE AN AREA OF LOW PRESSURE TO REFORM OVER/NEAR
SOUTHERN LAKE MICHIGAN THIS EVENING...THEN TRACKING THE LOW
NORTHEAST TONIGHT INTO MONDAY. THERE WILL BE A CHANCE FOR LIGHT
RAIN/DRIZZLE OVER MAINLY EASTERN AREAS TODAY...WITH THE BEST
CHANCE OVER OUR SOUTHEAST ZONES. CURRENT TEMPERATURES WERE IN THE
MID TO UPPER THIRTIES FOR MOST AREAS AS OF 09Z. THERE MAY BE SOME
SLICK SPOTS ON SOME ROADS THOUGH AS THOSE TEMPS MAY BE AT/BELOW
FREEZING.

COLDER TEMPERATURES WILL MOVE INTO WESTERN AREAS LATE TODAY...AND
SOUNDINGS/WET BULB TEMPERATURES SUGGEST PRECIP TYPE WILL
PROGRESSIVELY BECOME ALL SNOW FROM WEST TO EAST LATE TODAY INTO
TONIGHT. THE THREAT FOR FREEZING RAIN/DRIZZLE IS LOWER THAN PREVIOUSLY
EXPECTED. WE INCREASED CHANCES FOR SNOW LATE TONIGHT INTO MONDAY
FOR MOST AREAS AS MUCH COLDER AIR MOVES IN ON INCREASING NORTHWEST
WINDS. SNOW AMOUNTS ARE STILL IN QUESTION MONDAY...WITH THE
NAM/GEM SUGGESTING MUCH HIGHER AMOUNTS THAN WE HAD GOING. WE DID
INCREASE SNOWFALL...BUT DID NOT BUY INTO THE HIGH END AMOUNTS. THE
SREF PLUMES DEMONSTRATE THIS PROBLEM WITH THE 03Z RUN SHOWING
SNOWFALL SPREADS FROM NO ACCUM TO A COUPLE MEMBERS OVER 15INCHES
AT KDLH.

WE EXPECT WINDY CONDITIONS FOR MUCH OF THE NORTHLAND MONDAY...AND
HAVE SOME BLOWING SNOW MENTIONED. WE ARE NOT CONFIDENT ENOUGH TO
ISSUE ANY ADVISORIES FOR SNOW/BLOWING SNOW ON THIS SHIFT...BUT THE AREA
ALONG INTERSTATE 35 TO THE TWIN PORTS...INCLUDING ALL OF
NORTHWEST WISCONSIN AND THE ARROWHEAD OF MINNESOTA MAY SEE
CONDITIONS THAT WARRANT AN ADVISORY LATE TONIGHT INTO MONDAY. WE
WILL WAIT FOR ANOTHER SET OF MODELS AND LET THE NEXT CREW ADJUST
AS NEEDED.

WE ARE CONFIDENT ENOUGH TO ISSUE A WATCH FOR ASHLAND/IRON COUNTIES
FOR MONDAY INTO MONDAY NIGHT. SNOW FROM THE LOW WILL OCCUR
MONDAY...THEN THE LAKE WILL CONTRIBUTE ADDED SNOWFALL MONDAY
NIGHT. A GOOD FETCH WILL EXIST WITH 850MB TEMPS DROPPING TO AROUND
-12C CREATING FAVORABLE INSTABILITY.

TEMPERATURES MONDAY WILL PEAK EARLY...THEN DROP THROUGH THE DAY
AS THE COLD AIR POURS IN.

AREAS OF DENSE FOG CONTINUED THIS MORNING AND WE WILL EXTEND THE
ADVISORY THROUGH NOON AND INCLUDED THE NORTH SHORE ZONES AS WELL.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 324 AM CST SUN NOV 23 2014

LAKE EFFECT SNOW EVENT ALONG THE SOUTH SHORE OF LAKE SUPERIOR SHOULD
BE WINDING DOWN AT THE BEGINNING OF THE EXTENDED PERIOD TUESDAY
MORNING. THERE MAY BE SOME LINGERING LIGHT SNOW SHOWERS TUESDAY..BUT
AS 925/850 THERMAL TROF TRANSLATES EAST OF THE WRN GRT LAKES AND
WINDS BACK TO MORE WESTERLY AND DIMINISH IN SPEED AS GRADIENT
RELAXES..HEAT FLUX OFF THE LAKE SHOULD WANE FAIRLY RAPIDLY. THE
POTENTIAL FOR ANY ADDITIONAL SIG ACCUMULATION OVER BAYFIELD/IRON/
ASHLAND COUNTIES AFTER TUESDAY MORNING APPEARS RATHER SMALL.

MAIN ITEM OF ATTENTION THEN BECOMES WHAT INCREASINGLY LOOKS LIKE A
RATHER POTENT CLIPPER-TYPE SYSTEM FOR TUESDAY NITE/WEDNESDAY. MOST
OF THE AVAILABLE GUIDANCE BRINGS A VERY STRONG VORT MAX FROM N
DAKOTA TUE NITE TO S CENT WI BY WED EVENING..AND THE ASSOCIATED
SURFACE LOW TRACK ROUGHLY ALONG I94. IF CURRENTLY FORECASTED MODEL
MASS FIELDS ARE IN THE BALL PARK..A 6-9 HOUR PERIOD OF EXTREMELY
STRONG FORCING FOR ASCENT WILL TRANSLATE ACROSS THE CENTRAL AND
SOUTHERN DULUTH CWA.  CURRENT MODEL PROGS ALSO SUGGEST THE POTENTIAL
FOR STRONG MESOSCALE FRONTOGENESIS FORCING..IMPLYING THE POTENTIAL
FOR A NARROW BAND OF ENHANCED ACCUMULATIONS SOMEWHERE.  THE TWO
LIMITING FACTORS APPEAR TO BE THERMAL PROFILES..WHICH ARE NOT IN THE
IDEAL CRYSTAL GROWTH REGIMES..AND THE SPEED OF THE SYSTEM..WHICH WILL
ACT TO LIMIT THE DURATION.  STILL..IT APPEARS THAT THERE IS SOME
POTENTIAL FOR 4-5 INCH PLUS AMOUNTS..AND PERHAPS HEAVIER IF STRONG
FGEN EVOLVES AS CURRENTLY SUGGESTED BY THE MODELS.

ARCTIC AIR WILL THEN SPILL SOUTHWARD INTO THE REGION AGAIN IN THE
WAKE OF THE CLIPPER SYSTEM..WITH SCATTERED SNOW
SHOWERS/FLURRIES..AND THE POTENTIAL FOR MORE LAKE EFFECT
ACCUMULATIONS ON THE SOUTH SHORE. A SECONDARY REINFORCING SHOT OF
COLD AIR IS EXPECTED SOMETIME AROUND FRIDAY..WITH SIMILAR EFFECTS ON
SENSIBLE WEATHER.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 534 AM CST SUN NOV 23 2014

WIDESPREAD IFR CONDITIONS PERSIST EARLY THIS MORNING AS RELATIVELY
WARM/MOIST NEAR-SURFACE AIRMASS CONTINUES TO ADVECT OVER SNOW PACK
AND RESIDUAL COLD GROUND. THERE HAVE BEEN A FEW VERY LIGHT RAIN
SHOWERS AND DRIZZLE..BUT MOSTLY IT HAS BEEN A FOG AND LOW
CEILING/VSBY EVENT. THE THREAT OF FREEZING DRIZZLE APPEARS TO HAVE
TEMPORARILY ENDED AS TEMPS HAVE RISEN ABOVE FREEZING AT ALL TAF SITES.

LOW LEVEL TROF AXIS WILL MOVE EAST TODAY..AND WE HAVE TIMED THE
RAISING OF CEILINGS/VSBYS TO GENERALLY MVFR CONDITIONS WITH A
SWITCH TO WEST WINDS. THERE WILL BE A 4-7 HOUR TRANSITION TIME
WHERE MIXED PRECIP WILL BE POSSIBLE /PRIMARILY FZDZ AND -SN/ LATE
THIS AFTERNOON AND EARLY THIS EVENING..BUT SUFFICIENT LOW LEVEL
COLD ADVECTION IS EXPECTED TO PROMPT A CHANGE OVER TO ALL SNOW BY
LATE EVENING AT ALL THE MINNESOTA TAF SITES AS WINDS CONTINUE TO
VEER TO THE NORTHWEST AND INCREASE..ESPECIALLY DURING THE LAST 6
HOURS OF THIS TAF WINDOW. KHYR WILL BE THE LAST TO SWITCH OVER TO
SNOW..BUT SHOULD ALSO SEE THE HEAVIEST AND MOST SUSTAINED SNOW
TOWARD THE END OF THE TAF PERIOD IN CLOSER PROXIMITY TO SIG LOW
PRESSURE LIFTING NNEWD INTO LOWER MICHIGAN TONIGHT AND MONDAY.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  41  24  26   8 /  30  70  70  30
INL  38  18  18   2 /  20  50  60  10
BRD  40  19  21   7 /  20  50  50  10
HYR  48  28  29   8 /  50  80  80  50
ASX  47  30  31  13 /  50  90 100  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ018>021-025-026-
     033>038.

WI...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ001>004-006>009.

     WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING
     FOR WIZ003-004.

LS...SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 10 AM CST TUESDAY FOR
     LSZ121-148.

     SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 4 AM CST TUESDAY FOR
     LSZ141>147.

     GALE WATCH FROM LATE TONIGHT THROUGH LATE MONDAY NIGHT FOR
     LSZ140.

&&

$$

UPDATE...STEWART






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