Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200513
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
113 AM EDT Mon Mar 20 2017

.SHORT TERM...(This evening through Monday)
Issued at 341 PM EDT SUN MAR 19 2017

Strong upper trough moving from northern Manitoba to Hudson Bay will
push deep 987mb low from far northern Manitoba to southern Hudson
Bay by 12z Mon while deepening to 976mb. Sfc trough tied to the low
extends south to southern Mantioba and eastern North Dakota. Warm
front extends from that trough to the central Plains. SSE flow ahead
of trough is graudally bringing in warmer conditions, though it has
been a slower rise over Upper Michigan as flow is mainly coming off
Lk Michigan and there are sct-bkn middle clouds. Soundings upstream
indicated steeper mid-level lapse rates but they were also dry below
moist layer h7-h5. Stronger shortwave stays north of Lk Superior
this evening but tail end of that wave along with increasing h85-h7
moisture advection moving in from the west. That forcing along with
instability aloft results in isold-scattered showers developing over
MN and then moving across Lk Superior and Upper Michigan through the
evening.

Certainly does not feel like a thunder day outside attm as it cooler
and dry, but if convection can develop late this aftn into this
evening there could be thunder with mid-level lapse rates over
8c/km and RAP and HRRR indicating mucapes up to 400 j/kg.
Conditional potential but with low freezing levels would not take
much to get small hail in even the stronger showers. Strong winds
aloft with h85 winds up to 50 kts but think risk of having these
winds surface is low as all the shra and any tsra would be based
at h7 or 8-10kft. All precip should be clear of eastern cwa by
06z, though low clouds and/or fog may linger through much of
night. Best chances of fog would be over cntrl and east.

Low pressure trough crosses late tonight switching winds to the NW
on Monday. Low clouds will give way to plenty of sunshine in the
aftn as drier air moves in as large high building over cntrl Canada.
Cooler air gradually moves in but most areas should be able to reach
the 40s. Could even be warmer over the scntrl with downslope NW
winds and as there is little if any snow cover left. For those
areas, mixing to h85 temps 1-4c supports max temps reaching into
the low 50s.

.LONG TERM...(Monday night through Sunday)
Issued at 249 PM EDT SUN MAR 19 2017

Models suggest that a progressive pattern will prevail into next
weekend. After a brief cooldown from Tue into Wed with n-nw flow
LES, moderating conditions will follow by Thursday into Friday as a
low pressure system with widespread precipitation moves affects the
region. Temperatures will drop behind the system but should still
remain at or above normal.

Monday night through Wednesday, a shortwave trough sliding through
nrn Ontario will drag an arctic front through the nrn Great Lakes
Tuesday morning with much colder air dropping into the area on nnw
winds. 850 mb temps are expected to fall to around -18C by 00z/Wed
which will provide enough instability for LES development. However,
LES intensity will be limited by relatively low inversion heights
around 4k-5k ft with a very dry 850-700 mb layer and very dry low
level air upstream. The LES should diminish Wed morning as winds
become light and anticyclonic as the dry airmass associated with
1040 mb high pres builds into the region. Expect Snowfall amounts in
the 1 to 2 inch range per 12 hours at most and SLR values above 20/1
with DGZ through the convective cloud layer.

Thursday-Sunday, Model/ensemble spread is still relatively high with
the evolution of the cntrl plains shortwave and sfc low heading
toward the Great Lakes. The ECMWF and CMC slide the stronger 500 mb
low more to the east. There is still decent moisture transport
toward the cwa and support for pcpn with a nrn stream shrtwv and
fgen associated with the right entrance of the jet from nrn Ontario
into Quebec. This would still keep the heavier pcpn and warmer air
farther south compared to the GFS/GEFS. However, there is enough
agreement to maintain high pops for mixed pcpn that would likely
change to rain Friday as a warm layer spreads into the cwa. Some
snow or lake enhanced snow may be possible as colder air moves in
behind the system.
&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 112 AM EDT MON MAR 20 2017

Low pres trof will sweep across the area overnight/this morning.
Ahead of the trof, combination of earlier pcpn and diminishing low-
level winds may allow for fog and/or low clouds to develop at KSAW.
Potential appears less likely now, but will maintain some MVFR vis
in BR at KSAW for a time this morning. With the passage of the trof,
conditions will improve quickly to VFR mid to late morning with VFR
continuing thru the remainder of the fcst period as dry air mass
dominates in the low to mid levels. At KIWD/KCMX, VFR conditions
will prevail thru the fcst period.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 341 PM EDT SUN MAR 19 2017

At this time, no gales or heavy freezing spray are expected through
this week. Prevailing winds will mostly be in the 20-30 kt range.
Strongest winds will be Mon night into Tue evening as cold air moves
across Lk Superior.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLA
LONG TERM...JLB
AVIATION...Rolfson
MARINE...JLA



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