Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 190720
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
320 AM EDT Sun Mar 19 2017

.SHORT TERM...(Today and tonight)
Issued at 319 AM EDT SUN MAR 19 2017

Upper air pattern consists of a closed 500 mb low over Pennsylvania
this morning and a ridge across the plains which moves into the
upper Great Lakes today. Nam brings in some deeper moisture and 850-
500 mb q-vector convergence into the west late this afternoon and
the deeper moisture moves through quickly tonight. Still looks warm
enough for pcpn to be all rain tonight and kept it that way. The
freezing drizzle and light snow over the upslope areas of Marquette
County will end this morning as drier air slowly moves in. Overall,
did not make too many changes to the going forecast.

.LONG TERM...(Sunday night through Saturday)
Issued at 439 PM EDT SAT MAR 18 2017

After warming this weekend as a ridge shifts e into the Great Lakes
region, a trof will amplify into se Canada/ne CONUS Mon-Wed,
bringing a period of colder weather as the Upper Great Lakes are
brushed by a late season arctic air mass that will bring very cold
conditions to Quebec where 850mb temps will drop to sub -30C. Temps
will then moderate to around normal during the last half of the week
as ridging shifts to the eastern CONUS and arctic branch retreats n.
As for pcpn, a pair of shortwaves and associated cold fronts will
bring the colder conditions during the early part of next week,
though pcpn will be light. Pcpn with first fropa Sun night will
likely be just -shra. Second fropa may be accompanied by sct -shsn
Mon night with sct light LES to follow Tue into early Wed as 850mb
temps fall to -15 to -20C. Late week, attention will shift to
shortwave energy swinging thru the sw CONUS. Snow or mixed pcpn
could arrive as early as Thu as weak lead energy lifts ne toward the
Great Lakes. Main shortwave then arrives in the western Great
Lakes/lwr Ohio Valley on Sat, probably with more mixed of pcpn. At
this point, it does not look like a strong, wrapped up system.
Looking farther ahead, CPC/NAEFS outlooks in the 8-14 day period
(Mar 25-31) indicate temps probably not far from late Mar normals.
Into early Apr, recent days CFSv2 ensemble means have been
suggesting a preference for above normal temps across the Upper
Lakes.

Beginning Sun night/Mon, a vigorous shortwave trof will swing into
northern Ontario with associated cold front sweeping across Upper MI
roughly in the late Sun evening to early Mon morning time frame. Out
ahead of the front, a minor shortwave and a narrow axis of
instability are indicated by most models, potentially a few hundred
j/kg of elevated cape. Along with steep mid level lapse rates
upwards of around 7.5c/km and 40kt low-level jet, a narrow band of
isold to sct -shra may push across the area, and not out of the
question that there could be a few rumbles of thunder. Stong low and
mid level drying follows fropa into Mon though the NAM in particular
suggests some low clouds may occur for a short time after fropa.
Otherwise, with high clouds departing, expect a trend to sunny skies
on Mon which will aid temps rising into the 40s, and even lwr 50s s
central. Close to Lake Superior where w to nw winds have
trajectories across the lake, temps will be lower. Second cold front
then drops s across the area Mon night. With moisture limited, not
expecting much more than sct -shsn, especially closer to Lake
Superior.

Incoming dry air mass and increasingly anticyclonic flow as
influence of high pres over Manitoba expands into the Upper Lakes
will be strong negatives for LES on Tue despite 850mb temps falling
to -15 to 18c. Stronger mid/late Mar daytime heating will also
disrupt LES processes. Expect sct -shsn, mainly off the e half of
Lake Superior due to longer fetch and the lower 850mb temps in that
area. High temps Tue will range from roughly the upper 20s to
around 40F, warmest s central.

Light LES will linger Tue night, mainly off eastern Lake Superior,
before ending by Wed aftn as high pres moves over the Upper Lakes.
Expect min temps Tue night into the single digits/teens with max
temps on Wed into the mid 20s/30s.

Late week, as mentioned above, shortwave energy swinging across the
sw CONUS will move toward the Great Lakes/Ohio Valley. 00z ECMWF/CMC
were in fairly good agreement on late week evolution with both being
slower and more consolidated/farther s with the main energy in the
trof than the GFS. Unfortunately, the 12z ECMWF trended farther s
with the main energy, far enough s that most, if not all, of the
pcpn will stay s of the fcst area after some pcpn with lead weak
shortwave Thu/Thu night. Since bulk of Canadian ensembles still
support something more along the lines of the 00z ECMWF, fcst will
still retain high pops in the late week period. While likely not
becoming a well developed, wrapped up storm system, there certainly
could be decent pcpn amounts spreading well n into the Great Lakes
given a good tap of gulf moisture. At some point, cooling may become
sufficient to change rain and/or mixed pcpn to all snow as well.
Cooling will be determined to some degree by track/speed of arctic
branch shortwave dropping across Hudson Bay as following arctic high
pres building toward northern Ontario would provide a feed of
colder/drier air into the area at the lower levels.
&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 118 AM EDT SUN MAR 19 2017

At IWD, expect VFR conditions through the rest of the forecast
period. Southerly winds will become gusty as a trough approaches
Sunday.

At CMX, cigs will remain around 010 through tonight with lingering
moist layer trapped below subsidence inversion and since winds stay
off of Lk Superior. Low cigs should scatter out Sun morning with
broken mid clouds moving across.

For SAW, NW-N winds off Lk Superior will also keep cigs near 1k ft
through tonight. Low clouds should finally break out Sun morning
though with S-SE winds developing off Lk Michigan the low clouds may
be slower to depart.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 319 AM EDT SUN MAR 19 2017

Winds through the period look to stay 30 kts or less. Strongest
winds will be Mon night into Tue evening as cold air moves back
across Lk Superior. At this time, no gales or heavy freezing spray
is expected into next week.
&&

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

$$

SHORT TERM...07
LONG TERM...Rolfson
AVIATION...JLB
MARINE...07



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