Area Forecast Discussion
Issued by NWS Duluth, MN

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627
FXUS63 KDLH 211739
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1239 PM CDT Sat Oct 21 2017

.UPDATE...
Issued at 1239 PM CDT Sat Oct 21 2017

Updated for the new 18Z Aviation Discussion below.



UPDATE Issued at 721 AM CDT Sat Oct 21 2017

Added a mention of thunder to this morning over the southern
portion of the forecast area. This is due to thunderstorms
currently over southern and central Minnesota moving northward.
Rest of the forecast is on track.

&&

.SHORT TERM...(Today through Saturday)
Issued at 335 AM CDT Fri Oct 20 2017

An area of low pressure was located over south central Canada at
07Z. A cold front extended south from the low through the central
Dakotas, while a quasi-stationary front was north of the
Minnesota/Canada border. A stiff southerly flow of air/moisture was
working its way into the area ahead of the low on a strong low level
jet. Some sprinkles were dotting the forecast area, even though the
radar indicates there may be some better rain in northwest
Wisconsin. However, the very dry airmass that has been over the
region for the past week, is proving to be tough to overcome as
cloud bases are greater than 10K feet. After this initial surge of
sprinkles, there will be a break in the action as the potential
vorticity advection that is helping to initiate these sprinkles
moves off to the north. Next round of more robust showers is
expected to arrive later this morning as the next shot of vorticity
arrives from the South. The showers will overspread the region by
noon with some isolated thunder as well. Not expecting any severe
storms as MUCAPE remains below 1000 J/kg for most of the day. 0-6 km
shear is 25 to 30 knots in the afternoon. The best shear however
lags the MUCAPE axis. Expect the showers and isolated storms through
the afternoon.

The cold front begins to move into the western third of the forecast
area by 00Z, and reaches the far eastern edge of the region by 12Z
Sunday. Showers and a few thunderstorms will percolate across the
area tonight with the thunderstorms occurring ahead of the front.
The rain will end gradually from west to east through the night,
except for the far eastern edge where some showers may linger in the
vicinity of the front.

The front pushes out of the region Sunday morning accompanied by a
sharp upper level trof. Some rain will linger from the Arrowhead
into the Hayward Lakes area and points east in the morning due to
their proximity to the departing front and the upper trof. The rain
departs by the afternoon as the best forcing exits. No rain
elsewhere as a drier airmass works into the area from the West.

.LONG TERM...(Saturday night through Thursday)
Issued at 335 AM CDT Fri Oct 20 2017

Not a whole lot of change to the previous discussion as model
continuity continues giving a tad more confidence to the forecast.
Precipitation will slowly progress east out of the area on Sunday
morning with the remainder of the day remaining dry. The dry
weather will be short- lived as another shortwave pushes across
the region from the Dakotas into the Lake Superior region Sunday
night and Monday. An upper level trough will amplify across the
western Great Lakes Monday and Monday night, with upper level
shortwave energy bringing unsettled weather to the Northland. Some
snow showers will even be possible Monday night and early
Tuesday, as colder air pours into the area from Canada. This upper
level low and amplifying trough will dominate the weather across
the Great Lakes region at least into midweek.

The best chance of precipitation throughout the long term period
will be Thursday night. Temperatures drop considerably to below
seasonable norms by Tuesday morning. A slight warm up on Thursday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1239 PM CDT Sat Oct 21 2017

Showers and widespread IFR/MVFR ceilings across the Northland this
afternoon and into this evening. Thunderstorms are possible later
this afternoon and this evening when a cold front moves in from
the west. Expect lifting back to VFR in the wake of the cold front
late today and tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  63  45  57  44 /  90  80   0  10
INL  66  41  59  42 /  70  80   0  30
BRD  65  41  59  45 /  50  50   0  10
HYR  67  47  60  43 /  80  80  20   0
ASX  69  49  61  43 /  60  90  30  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 7 PM CDT this evening for LSZ121-140-
     141-145>148.

&&

$$

UPDATE...Grochocinski
SHORT TERM...GSF
LONG TERM...JW/DAP
AVIATION...Grochocinski



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