Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 221841

Area Forecast Discussion
National Weather Service Marquette MI
241 PM EDT Sun Apr 22 2018

.SHORT TERM...(This evening through Monday)
Issued at 241 PM EDT SUN APR 22 2018

Upper air pattern consists of a closed 500 mb low over Arkansas with
another over eastern Saskatchewan with a shortwave ridge over the
upper Great Lakes. The ridge moves into the lower Great Lakes while
both closed lows stay well to the north and south of the area. This
means quiet and mild weather will continue this forecast period.
Lowered dew points a bit based on persistently dry airmass and
models were way too high on their sfc dew points. These were the
only major changes made to the going forecast.

.LONG TERM...(Monday through Saturday)
Issued at 357 AM EDT SUN APR 22 2018

Broad upper ridging to start the week but by mid week a northwest
flow aloft will develop. Indications are this cooler northwest flow
aloft will likely persist into next weekend and on into early next
week, which includes the first day of May.

A couple sharper upper level and sfc troughs are expected to swing
across the Upper Great Lakes this week as the upper air pattern
transitions to more of a northwest flow aloft. Ahead of the first
trough on Mon, southwest sfc winds combined with H85 temps rising to
+5c should result in what will be the warmest day so far this
spring. Expect highs well into the 60s and agree with previous shift
that a 70F reading is possible, especially in downslope areas near
Lk Superior. GFS MOS for IMT picks up on the warmth with 70F now
pegged there for Mon.

Initial trough then moves through on Tue, with a stronger system
following on Thu. GFS most aggressive with both troughs in terms of
bringing precip to the area, especially on Tue when it is the only
model of the primary 00z models showing notable qpf. GEFS
ensembles not as bullish with precip on Tue and especially not on
Thu. The late Thu into Thu night system could also result in rain
changing to snow with minor snow accumulations possible,
especially over the west and north closer to Lk Superior. GFS much
more wrapped up than other models and GEFS ensembles in its
depiction with Thu-Thu night system as it shows main upper trough
closing off for at least a little while and a very sharp sfc low
down to 995mb dropping across Lk Superior and Upper Michigan
leading to lake enhancement with convergent north winds. GFS has
hinted at this over past many runs but this run is one of the
stronger solutions. No need to go that route now, but probably
looking at rain showers mixing with and changing to snow showers
Thu night into Fri morning.

Another impact from both of these troughs this week, in addition to
temps falling back below normal in their wake, will be gusty
northwest to north winds. Strongest winds, with gusts possibly over
30 mph, would occur along Lk Superior Tue night and late Thu night
into Fri especially between Marquette and Whitefish Point.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 102 PM EDT SUN APR 22 2018

With high pressure dominating the region, VFR conditions are
expected through the TAF period with light winds.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 241 PM EDT SUN APR 22 2018

Winds will remain less than 15 knots through most of the period. The
main exception will be later Tue into Tue night when northwest winds
increase to over 20 knots. Another period of strong wind will arrive
late Thu into Thu night with winds to around 30 knots in the wake of
a cold front moving across Lake Superior.

Issued at 241 PM EDT SUN APR 22 2018

Snowpack continues to melt steadily since late last week. Though the
melt so far has been slow for most areas, expect it to increase
through Tuesday as daytime highs reach the 60s inland. However, dry
airmass with sub freezing dwpnts should result in a slower melting
of snow than would otherwise occur with these temps. Fortunately,
still looks like we will avoid any bigger precipitation events the
next week which would only increase runoff and flooding potential.
Cool down at the end of the week should really slow down the melt.
Overall, observed and forecast conditions don`t suggest any
significant concerns with the snow melt for the next week. While
melting will likely be relatively controlled given the forecast,
certainly could still see minor flooding at some point down the road
on the usual rivers that experience spring flooding.

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


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