Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 162350
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
550 PM CST Thu Feb 16 2017

.SHORT TERM...(This evening through Friday)
Issued at 506 PM CST Thu Feb 16 2017

At 300 PM...A prominent upper-level ridge was over the central US
and central Canada, and a warm front extended from northern
Manitoba to western Minnesota and into Iowa. The Northland had
scattered upper-level cloud cover and breezy southerly winds,
except the Duluth area had light easterly flow from Lake Superior.
Temperatures across the Northland were in the 30s.

Tonight...The warm front will move through the Northland. Some
partial clearing by sunset will contribute to radiational cooling
and the development of the near-surface inversion. Light winds
will develop. Several models are indicating stratus and/or fog
will develop tonight. The NAM, GFS, RAP, and HRRR are among these
models. Considering the added moisture from the today`s melting
snowpack, think this is certainly possible. Some of the models
seem too excessive with the extent of the low-level stratus
though, a pattern seen over the past few weeks, so focused on
forecasting tonight`s cloudier skies to where the models had good
agreement on where the depth of the saturated layer will reach
about 925 to 900 hPa. This resulted in forecasting broken/overcast
cloud cover for the Iron Range and inland Arrowhead, as well as a
bit for the Duluth area. Think this stratus will develop after
sunset. There will also be some lingering upper-level clouds
tonight, so the 40% to 60% cloud cover forecast for other areas
not only accounts for this upper cloud cover, but also for the
possibility of some low stratus. Think there is a bit too much
wind flow to add fog to the forecast, but there could be isolated
fog. Lows should be in the middle to upper 20s.

Friday...Very unusually warm air will build into the Northland
amidst westerly winds aloft. For instance, the 850 hPa
temperatures will build to 9 to 13 degrees Celsius. A very shallow
inversion, and the lack of wind flow in the shallow mixing layer,
though, will prevent the Northland from fully realizing this
warmth. Nonetheless, light southwest flow and sunny skies will
help temperatures climb to near-record territory. Leaned on the
warmest model guidance, namely towards the regional Canadian,
given the scenario. Avoided forecasting quite as warm as the
regional Canadian, though, given the lack of low-level mixing.
Highs should reach well into the 40s, and in some areas the low
50s. The forecast and respective record temperatures for the date
include Duluth (48 and a record of 51 in 1951), International
Falls (52 and a record of 1907), and Brainerd (51 and a record of
54 in 1951).

.LONG TERM...(Friday night through Thursday)
Issued at 506 PM CST Thu Feb 16 2017

Unseasonable warmth will continue through the weekend, but a
storm system is forecast to bring a mix of rain and snow, and a
chance of isolated thunderstorms, to the Northland early next
week.

A high-amplitude ridge axis aloft will be located east of the
Northland Friday evening with a potent shortwave trough stretching
from the northern Canadian Prairies into the Northern Plains.
Moisture is forecast to be extremely limited with this system. A
period of increased cloud cover will be the only sensible weather
feature to mark the passage of the system`s weak cool front. Very
mild conditions are expected through the weekend and into early
next week. High temperatures will be in the upper 30s to middle
50s with overnight lows from the middle 20s to the upper 30s. The
mild temperatures should work to melt some of the snowpack across
the area, which will support the development of fog overnight
Saturday, Sunday, and early Monday morning.

A more significant pattern shift will arrive late Sunday
afternoon continuing through mid-week. A deep upper trough will
advance eastward across the Rockies Sunday and into the Midwest by
Monday. Lee cyclogenesis is forecast in Colorado and Wyoming
early Monday morning with the storm system lifting northeastward
into northwest Ontario by late Monday night. With the upper-level
ridge pushing farther east of the region, southerly flow and a
surge of Gulf moisture will be available for the early week
system. A mix of rain and snow is favored for our northern zones
Monday and Monday night, with mainly rain across the southern half
of the CWA. The deterministic models all have non-zero MUCAPE
along and ahead of the advancing cold front, so have introduced
isolated thunderstorms with the rain showers Monday afternoon and
evening.

Another weak disturbance will move across the Northland late
Tuesday night and Wednesday yielding a slight chance of rain or
snow showers, mainly over far northern Minnesota. Temperatures are
expected to remain above to much above normal through Thursday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 550 PM CST Thu Feb 16 2017

VFR conditions were occurring across the Northland as of early
evening. Continued warm air advection will lead to increasing
clouds overnight, first mid and upper level clouds and possibly
lower ceilings as the night progresses. The models remain mixed on
if LIFR/IFR/MVFR ceilings form overnight and how widespread they
would become. The combination of lowering winds, added moisture
from snowmelt, and warm air advection will bring the threat for
lower ceilings to portions of the Northland. We did delay bringing
in the lower ceilings at most TAF`s tonight by a couple of hours.
There may also be some fog that forms tonight.

We left the mention of drizzle/freezing drizzle out of the
forecast for now as the probability is too low to include at this
time.

Conditions will improve to VFR through the day Friday.

&&

.CLIMATE...
Issued at 506 PM CST Thu Feb 16 2017

Record Warmest Lows for February 17...

Duluth................ 34 in 1981
International Falls... 33 in 1998

Record Highs for February 17...

Duluth................ 52 in 1981
International Falls... 52 in 1907

Record Warmest Lows for February 18...

Duluth................ 35 in 1981
International Falls... 35 in 1981

Record Highs for February 18...

Duluth................ 53 in 1981
International Falls... 49 in 1954

Record Warmest Lows for February 19...

Duluth................ 35 in 1930
International Falls... 32 in 2016


Record Highs for February 19...

Duluth................ 51 in 1930
International Falls... 47 in 1994

Record Warmest Lows for February 20...

Duluth................ 33 in 1954
International Falls... 32 in 1915

Record Highs for February 20...

Duluth................ 54 in 1877
International Falls... 48 in 1990

Record Warmest Lows for February 21...

Duluth................ 33 in 1878
International Falls... 29 in 1981

Record Highs for February 21...

Duluth................ 57 in 1877
International Falls... 50 in 2000

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  28  48  33  46 /   0   0   0   0
INL  26  48  32  42 /   0   0  10   0
BRD  28  51  33  48 /   0   0   0   0
HYR  24  50  32  48 /   0   0   0   0
ASX  26  50  33  49 /   0   0   0   0

&&

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

$$

SHORT TERM...Grochocinski
LONG TERM...Huyck
AVIATION...Melde
CLIMATE...WM/Huyck


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