Area Forecast Discussion
Issued by NWS Duluth, MN

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503
FXUS63 KDLH 191141
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
541 AM CST Sun Feb 19 2017

.SHORT TERM...(Today through Monday)
Issued at 314 AM CST Sun Feb 19 2017

Some light fog has developed around the Brainerd Lakes area this
morning, which may expand through the mid-morning hours today as a
sfc high pressure ridge continues to slowly move to the east. The
ridge axis should be situated over our far eastern counties by 12Z
this morning, and nearly out of the forecast area by 15Z. As
temperatures increase this morning, any fog that does develop will
diminish. Mid to high clouds will advance into the region today,
but a dry low-level profile as indicated by latest RAP model
soundings should keep conditions dry today.

The big story for the short-term period will be a potent mid- to
upper-level system that will bring chances of precipitation across
the Northland. An upper-level trough will translate northeast across
the Intermountain West states, into the region. An intensifying
upper-level jet streak will support upper-level divergence, along
with an associated mid-level trough and sfc cold front. The
19.00z GFS/NAM models are showing strong isentropic lift with this
system. The thermal profiles are still suggesting p-types to be
all rain, which has been the going trend for the last several
days. One question mark has been the potential for thunder as
instability has been somewhat marginal. 0-1 km MLCAPE values are
fairly small, with values approximately up to 50 J/kg.
Investigation of the NAM/GFS soundings are more favorable for
elevated CAPE, with higher values between 100-200 J/kg. The Storm
Prediction Center does have an area south of a Brainerd Lakes to
Taconite Harbor line, and all of northwest Wisconsin within the
"general" thunder mention. The best destabilization appears to be
along our southwestern counties, so will continue mention of
isolated thunder mainly along our southwestern one-third of the
forecast area for Monday afternoon. The GFS is indicating a good
push of southerly flow, which will increase moisture through the
column. Pwat values over 1 inch are progged by the GFS model, so
QPF amounts should be pretty substantial with this system. Through
Tuesday morning, total QPF amounts could range between one-
quarter to three-quarters of an inch across the Northland. The
heaviest rainfall amounts appear to be on Monday afternoon, so the
afternoon commute looks to be a wet and drab one. Moreover, a
tightening sfc pressure gradient and intensifying 850 mb level
winds will support gusty southerly winds Monday, with gusts
possibly up to 25 knots.

.LONG TERM...(Monday night through Saturday)
Issued at 253 AM CST Sun Feb 19 2017

The cold front exits the forecast area Monday night bringing an
end to the precipitation from west to east. The instability is
lost quickly at 00Z Tuesday and have removed the mention of
thunder. By late Monday night, a mix of rain and snow is possible
along the east end of the BWCAW to Grand Portage as temps cool. A
break from the precipitation comes Tuesday and Tuesday evening as
high pressure drifts overhead. 850mb temps are still warm, from 5
to 8C and max temps will be well above normal with near record
highs possible. Tuesday night through Wednesday night an area of
low pressure will scoot through the region, starting in the
Dakotas, move through southern Minnesota and reach the eastern
Great Lakes by 12Z Thursday. Expecting a mix of rain and snow,
rain or snow as the temps will be borderline for any one ptype.
The passing of the low still points to the start of a pattern
change and a return to a winter regime. 850mb temps begin in the
single digits celsius Tuesday night and drop into the single DIGS
below zero celsius late Wednesday night. Model differences begin
to show up Thursday through Saturday with regards to the
possibility of a snow event. The ECMWF is the most bullish taking
the system from southeast Colorado through Green Bay. The GFS is
farther southeast with its low track from southeast Colorado to
southern lower Michigan. The GEM track is to the northwest of the
ECMWF and slower. Used a blended approach to account for these
differences, which favors the GFS. This system will have temps
cold enough so that the majority of the precipitation will fall as
snow. Some accumulation is expected, but the track differences
preclude any mention at this point.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 541 AM CST Sun Feb 19 2017

High pressure will drift east of the terminals this morning. Some
patchy fog at BRD will quickly erode after mixing begins and
should be gone by 15Z. Elsewhere, VFR is forecast. Look for LLWS
to affect all terminals from 02Z through 12Z as a low level jet
passes nearby.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  50  36  49  35 /   0  10  90  60
INL  49  37  50  32 /   0  10  90  60
BRD  55  43  55  33 /   0  20  70  20
HYR  54  40  54  37 /   0  10  90  70
ASX  54  36  56  39 /   0   0  90  70

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...JTS
LONG TERM...GSF
AVIATION...GSF



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