Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 202337
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
637 PM CDT Thu Apr 20 2017

.UPDATE...
Issued at 637 PM CDT Thu Apr 20 2017

Please see the 00Z Aviation Discussion below.

&&

.SHORT TERM...(This evening through Friday)
Issued at 333 PM CDT Thu Apr 20 2017

Rain and snow across the Northland will gradually diminish from
the west through this evening as an area of low pressure moves
through the Great Lakes region. The associated upper-level low,
which is causing widespread synoptic lift to drive the rain and
snow, will move from its current location near Bayfield Peninsula,
to the Keweenaw Peninsula by early this evening, so the synoptic
lift will shift east soon. The areas most likely to see snow are
along and near the higher terrain of the North Shore, including
from the higher terrain of Duluth up to the far North Shore. Most
areas should get little if any additional snow accumulation
because of melting or lack of falling snow.

There will be clearing skies from the north and west overnight
into Friday as the low exits to the east, while high pressure will
build into the region. Mostly clear skies and very light wind
speeds will develop by late tonight. Considering today`s humidity
and precipitation, patchy fog is possible across much of the
Northland early Friday.

The high pressure will provide a sunny and dry day for the
Northland. Highs should reach the middle 50s to low 60s, with this
forecast being slightly warmer than the previous forecast. The
coolest areas will be near the Lake Superior shoreline because of
a weak lake breeze.

.LONG TERM...(Friday night through Thursday)
Issued at 333 PM CDT Thu Apr 20 2017

The long-term forecast will be highlighted by some chances of
light precipitation, with some snow possible, and some slightly
cooler than normal temperatures.

Friday night and Saturday morning look dry at this point due to
high pressure in control over the region. However, chances of rain
showers will increase through the afternoon and evening as a cold
front boundary draped along an area of low pressure dives
southward. Resulting rainfall amounts should be light with this
boundary. Some snow may mix in with the rain Saturday evening and
into Sunday morning. Saturday looks to be the warmest day of the
long-term period, thanks to northwesterly winds keeping the cooler
temperatures over Lake Superior at bay. Highs Saturday should
range from the upper 50s north to the lower 60s south.

The baroclinic zone associated with this cold front boundary will
actually pivot northeastward due to increased 850 mb winds as the
low-level jet strengthens. Warm air advection will become
enhanced as evident by the 850-700 mean layer warm air advection
in the latest model guidance. Precipitation chances will linger
due to this warm front aloft, which will persist through the day
Monday as a mid- level shortwave trough moves into the region,
reinforcing the warm air advection. The best chances of
precipitation will be over the northern one-half of forecast area
since that is where the strongest isentropic upglide will
coincide. Some snow could once again mix in with rain showers.

Another mid-level wave could bring another shot of precipitation,
especially over northwest Wisconsin, for Wednesday morning
through Thursday. However, there is some uncertainty between the
GFS/ECMWF/CMC models. The ECMWF model appears to be the driest at
this time, with the GFS as the quickest model, and the CMC model
has the highest QPF amounts. Due to the uncertainty during this
time period, I leaned toward the consensus blends for the POPs.
Temperatures for Monday through Thursday don`t really change much
at all, with some cooler temperatures along Lake Superior due to
east to northeasterly on-shore flow. High temperatures for this
period will range from the lower to mid 40s north to the upper 40s
and lower 50s south.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 637 PM CDT Thu Apr 20 2017

An area of low pressure will lift northeastward into the Central
Great Lakes this evening, while high pressure builds into the
region from the Northern Plains. This will gradually bring
precipitation to an end from west to east as the night
progresses. Expect some snow to mix in with rain at KHYR and
potentially KDLH per the latest RAP/NAM BUFKIT soundings. This
should bring some visibility reduction this evening.

Expect skies to clear across northeast Minnesota tonight with high
pressure building in. The combination of recent precipitation,
light winds and clear skies will result in fog formation. Most
confident in fog development at KBRD, but less certain at
KDLH/KHIB as skies will take longer to clear. For now kept
KDLH/KHIB in the MVFR range for fog tonight, but will need to
lower if skies clear quicker than currently thinking. Expect IFR
and potentially LIFR fog to develop at KBRD late tonight. Will see VFR
conditions around 13 to 15Z on Friday once fog dissipates. On
Friday, winds will generally remain less than 10 knots out of the
northwest.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  31  55  35  61 /  30   0   0  10
INL  32  61  36  55 /  10   0   0  30
BRD  33  60  36  64 /   0   0   0   0
HYR  32  57  31  63 /  10   0   0   0
ASX  32  54  32  65 /  50   0   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 1 AM CDT Friday for LSZ145-146.

     Small Craft Advisory until 9 AM CDT Friday for LSZ121-140>144-
     147-148.

&&

$$

UPDATE...WL
SHORT TERM...Grochocinski
LONG TERM...JTS
AVIATION...WL



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