Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 162048
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
348 PM CDT THU APR 16 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 348 PM CDT THU APR 16 2015

AN UPPER LEVEL TROF COLLOCATED WITH ITS SFC TROF WILL MOVE THROUGH
THE REST OF THE FORECAST AREA LATE THIS AFTERNOON. ENOUGH UPPER
LEVEL DIVERGENCE COUPLED WITH LOW LEVEL CONVERGENCE TO GENERATE SOME
SHOWERS OVER THE MN ARROWHEAD AT 19Z. EXPECT THESE SHOWERS TO
PERSIST UNTIL NEAR 00Z. AMOUNTS HAVE BEEN ABOUT ONE HUNDREDTH OF AN
INCH OR A TRACE. AFTER 00Z IS WHEN THE TROF/FRONT ARE EXPECTED TO
MOVE EAST OF THE AREA AND UPPER LEVEL DIVERGENCE MOVES AWAY. BEHIND
THESE FEATURES...HIGH PRESSURE WORKS INTO THE FORECAST AREA WITH A
GRADUALLY CLEARING SKY.

ANOTHER COLD FRONT IS PROGGED TO MOVE INTO NE MN LATE FRIDAY
AFTERNOON. THIS FRONT HAS VIRTUALLY NO MOISTURE TO WORK WITH AND NO
RAIN IS EXPECTED. CLOUD COVER WILL ALSO BE AT A MINIMUM. THE ONLY
AFFECT WILL BE AN INCREASE IN WIND SPEED IN THE AFTERNOON BETWEEN
THE CANADIAN BORDER AND THE IRON RANGE. ONE MORE ABOVE NORMAL TEMP
DAY WITH MAX TEMPS IN THE 60S TO LOWER 70S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 348 PM CDT THU APR 16 2015

THE MAIN FOCUS IN THE EXTENDED FORECAST PERIOD IS THE LARGE UPPER
LOW THAT IS FORECASTED TO CLOSE OF IN THE VICINITY OF WESTERN LAKE
SUPERIOR FOR MUCH OF NEXT WEEK.

AHEAD OF THIS SYSTEM..DRY EAST/SOUTHEAST WINDS ARE LIKELY TO DEVELOP
WHICH WILL LIKELY RESULT IN A FAIRLY DRY BOUNDARY LAYER ONCE AGAIN
ON SATURDAY.  THERE IS STILL MUCH UNCERTAINTY ON THE NORTHWARD
EXTENT OF PRECIP SATURDAY AFTERNOON..AND SOME OF THE SOUTHERN AREAS
OF THE CWA COULD SEE A FEW SHOWERS.  HOWEVER..VERY LOW HUMIDITIES
ARE EXPECTED ONCE AGAIN FOR MUCH OF THE LATE MORNING AND AFTERNOON
ACROSS INTERIOR SECTIONS OF NW WI..AND MUCH OF MN NORTH OF THE
HIGHWAY 2 CORRIDOR.  THIS COULD ONCE AGAIN LEAD TO SOME SIGNIFICANT
FIRE WEATHER CONCERNS..ESPECIALLY WITH THE INCREASED WINDS.

BY LATE SATURDAY AFTERNOON/EVENING..THE FLOOD GATES SHOULD BE OPEN
FOR SIGNIFICANT MOISTURE RETURN AND RATHER WIDESPREAD PRECIP WITH A
30-40 KT SOUTHERLY LOW LEVEL JET IN ADVANCE OF THE APPROACHING UPPER
TROF AND DEEPENING SURFACE CYCLONE. RIGHT NOW..IT APPEARS THAT THE
REAL MONEY TIME FOR RAIN WILL BE FROM SOMETIME LATE SATURDAY EVENING
THROUGH SOMETIME MIDDAY SUNDAY WHEN A RATHER WIDESPREAD SHIELD OF
RAIN SHOULD BE ABLE TO PROPAGATE N/NEWD ACROSS THE REGION.  MOST OF
THE MODEL GUIDANCE IS HOLDING ANY APPRECIABLE MUCAPE VALUES TO THE
SOUTH OF OUR AREA..SO WE HAVE LEFT A MENTION OF THUNDER OUT FOR THIS
ISSUANCE. HOWEVER..WE WOULD NOT BE SURPRISED TO SEE ELEVATED
INSTABILITY AND AT LEAST SOME CHANCE FOR THUNDER SPREAD FARTHER
NORTH THAN CURRENTLY PROGGED WITH SUCH STRONG SOUTHERLY FLOW JUST
OFF THE SURFACE.

THE SURFACE LOW WILL SLOWLY LIFT INTO CANADA FROM SUNDAY INTO
MONDAY..BUT THE UPPER LEVEL LOW IS THEN FORECASTED TO CLOSE OFF AND
TAKE UP RESIDENCE FOR MUCH OF NEXT WEEK ALMOST DIRECTLY OVERHEAD.
FAIRLY COLD TEMPS ALOFT /850 TEMPS -5 TO -10C/ SHOULD KEEP LOW LEVEL
LAPSE RATES FAIRLY STEEP..AND THE RESULT SHOULD BE PERIODIC CHANCES
FOR RAIN AND SNOW SHOWERS. COVERAGE OF SHOWERS WILL LIKELY BE
ENHANCED BY DAYTIME INSTABILITY..AND ALSO ANY PERIODIC WEAK IMPULSES
ROTATING THROUGH THE FLOW ON THE SOUTHWEST PERIPHERY OF THE LARGE
UPPER LOW CIRCULATION.  PRECIP TYPE WILL LIKELY BE HIGHLY DEPENDENT
ON BOUNDARY LAYER TEMPS AND DEPTH..WITH MOSTLY RAIN SHOWERS IN THE
AFTERNOONS/EVENINGS..AND EITHER A RAIN/SNOW MIX..OR ALL SNOW DURING
THE LATER NIGHTS AND MORNINGS.  THERE WILL ALSO BE A PROPENSITY FOR
MORE SNOW CLOSER TO THE CORE OF COLD TEMPS ALOFT OVER THE MN
ARROWHEAD..WHERE HIGHER TERRAIN WILL ALSO ASSIST IN COLDER SURFACE
TEMPS. OVERALL..MUCH OF NEXT WEEK LOOKS MOSTLY CLOUDY..COOL TO
COLD..WITH CONSIDERABLY HIGHER HUMIDITIES THAN WE HAVE SEEN MUCH OF
THIS WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 107 PM CDT THU APR 16 2015

VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS. A WEAK
DISTURBANCE WILL BRUSH ACROSS THE MN ARROWHEAD THIS
AFTERNOON/EVENING..AND A WEAKENING COLD FRONT/SURFACE TROF WILL
SLOWLY SAG SOUTHWARD IN RESPONSE. AHEAD OF THIS FEATURE..WINDS
WILL BE FROM THE SOUTHWEST 5-10KT..WITH A SHIFT TO THE WEST AND NW
AFTER THE BOUNDARY PASSES FROM MID AFTERNOON TO MID EVENING. THE
BOUNDARY WILL STALL SOMEWHERE FROM CENTRAL MN INTO NW WI OVERNIGHT
AND WASH OUT AS WEAK SURFACE HIGH PRESSURE BUILDS INTO THE AREA.
WINDS WILL LIKELY BE LIGHT AND VARIABLE AT MOST TAF SITES FROM
LATE THIS EVENING THROUGH MID MORNING FRIDAY. KHIB/KINL SHOULD SEE
SW WINDS 5-10 KT DEVELOP AFTER 15Z FRIDAY IN ADVANCE OF A STRONGER
DISTURBANCE IN ONTARIO APPROACHING THE AREA. OTHERWISE..SCT- BKN
6-10 KT FT CEILINGS WILL PERSIST THIS AFTERNOON WITH A FEW VERY
LIGHT/BRIEF SHOWERS AROUND. HOWEVER..CONFIDENCE ON A SHOWER COMING
OVER ANY PARTICULAR TAF SITE IS EXTREMELY LOW.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  42  68  38  55 /   0   0   0  10
INL  37  70  32  61 /   0   0   0   0
BRD  36  71  41  63 /   0   0  10  20
HYR  43  70  38  64 /   0   0  10  20
ASX  41  72  36  59 /   0   0   0  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.

&&

$$

SHORT TERM...GSF
LONG TERM...MILLER
AVIATION...MILLER





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