Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 261113

Area Forecast Discussion
National Weather Service Marquette MI
613 AM EST Wed Feb 26 2020

.SHORT TERM...(Today and tonight)
Issued at 307 AM EST WED FEB 26 2020

With the LES machine turned on, snow showers will persist within
the NE to NNE wind belts through at least the first half of today
before transitioning more into the N wind snow belt regions later
today into tonight. Upper trough axis swinging across the Upper
Great Lakes later today into tonight will provide a synoptic
assist, with some deeper layer moisture accompanying it. However,
the key word here is "some" as the moisture doesn`t seem to be
too robust above the 850mb to around 800mb height range.
Additionally, despite a colder airmass arriving with said trough,
the delta T between the forecast temps and Lake Superior`s average
water temperature currently (around 34 degrees) will be marginal
in the latent heat release process. All of that said, the bottom
line is that while snow showers are expected, the amounts should
remain below advisory criteria for most locations. The high-res
models seem to be running a little hot in the QPF for this short-
term time frame, so backed off on those amounts. The caveat to all
of this, of course, is that near-advisory criteria snow amounts
may come to fruition in the higher terrain, but given that these
higher amounts will be localized (and still marginal), no
headlines appear to be necessary for this forecast issuance. Snow
amounts today and tonight will generally range from less than an
inch for locations along the edges of the aforementioned snow belt
regions, with about 2" to around 4" within those main belts.
Locally higher amounts within the higher terrain, as discussed,
could range closer to 4" - 6", but again, this is within a
24-hour period and subject some variability.

As for temperatures across the U.P., expect highs today to reach
the 20s, warmest in the south-central. Lows tonight will revisit
the single digits in the interior, mainly interior west, with
teens expected elsewhere. Widespread cloud coverage dominating
tonight should keep temps to more of a typical diurnal trend.

.LONG TERM...(Thursday through Tuesday)
Issued at 250 AM EST WED FEB 26 2020

Models indicate that a slowly progressive pattern will prevail into
next week with mid/upper level troughing through the central CONUS
for the latter half of this work week giving way to ridging by
Sunday and southwest flow early next week as a trough moves into the
west. After cold conditions with northerly flow LES late week, temps
will climb back above average by Sunday. Snow/rain chances are then
expected early next week as moisture and another weak system move
back into the region.

Thu, slowly backing winds to nnw will gradually shift the best low
level convergence and heavier bands into the east half, especially
later in the day. Surface ridging with low level dry air into
western Lake Superior will limit any additional accumulations from

Thu night into early Fri, nw low level flow with continued deep
moisture through 700 mb and 850 temps around -18C will bring the
potential for additional moderate to possibly heavy LES into the
east half, especially with possible enhancement from the mid-level
trough hanging over the area and if lake induced troughing and land
breeze development result in stronger dominant bands from enhanced
low-level convergence. The signal for some heavier snow also looks
good in the fcst soundings with a "crosshair" signature of the
better model omega aligned with the DGZ within the lake-induced
convective layer which should result in fluffier accumulation.

Sat-Sun, the LES should taper off on Saturday as the sfc ridge moves
in, winds become lighter, low-level convergence weakens and 850 mb
temps gradually moderate. WAA will boost temps into the upper 20s
Sat with a decent amount of sunshine and into the lower to mid 30s
on Sun.

Mon-Tue, precipitation chances will increase by Monday as a sfc
trough and a weak mid level northern stream trough approaches with
increasing moisture advection. However, confidence is low with the
timing given model differences and pcpn type could be an issue with
a few models showing 850 mb temps near or maybe slightly above

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 553 AM EST WED FEB 26 2020

MVFR ceilings are dominating at all three terminals this morning
as lake-effect snow showers fall within the NE to NNE wind snow
belt regions. This trend will continue through the rest of this
TAF period, with some lowered visbys possible tonight as more
stout snow bands attempt to start setting up. However, haven`t
dropped visbys much for this issuance since the more significant
lowered visbys will be confined to wherever said bands end up
setting up. It is possible that the more moderate snow showers
remain outside of the terminal areas tonight. Winds will gain a
more northerly to perhaps north-northwesterly component tonight,
with an uptick in magnitudes, particularly at KSAW where the
pressure gradient will be tighter.


.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 433 AM EST WED FEB 26 2020

NE to N wind gusts today into tonight may very well creep into the
mid-20 mph range, with them increasing by tomorrow, particularly
in the east half. By later tomorrow into Friday as the pressure
gradient tightens overhead, some marginal/occasional gale-force
gusts may be possible, again, primarily in the east half. These
northerly winds will settle down and become more northwesterly
into the start of the weekend, with sustained winds remaining
under 20 knots through at least early next week. Some 20+ knot
gusts may creep back into the area early next week, but otherwise
looks to be on the unremarkable side for marine interests.

Moderate to potentially heavy freezing spray may become
increasingly a concern late tonight into tomorrow as those
aforementioned winds increase.

Upper Michigan...
Lake Superior...
Lake Michigan...


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