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Area forecast discussion 
National Weather Service Marquette Michigan
110 PM EDT sun Mar 29 2015

Short term...(today and tonight)
issued at 524 am EDT sun Mar 29 2015

WV imagery and RUC analysis indicated a well a vigorous well-defined
shortwave trough over the Dakotas moving toward the western Great Lakes
as the middle/upper level pattern becomes more zonal. The shortwave
supported an area of rain across northwest into ernl Minnesota. Some thunderstorms and rain had also
developed near msp at the nose of a strong srly low level jet. At
the surface...a 996 trough extended across northwest Ontario into the northwest
corner of Minnesota. Brisk srly winds and warm air advection prevailed from the upper MS
valley into the western lakes in the tight pressure gradient between the
trough and a 1030 mb high over the eastern Ohio Valley.

Today into this evening...300k-305k isentropic lift with the
intitial band of precipitation and 700-300 mb qvector conv ahead of the
shortwave will be strong enough to produce quantitative precipitation forecast amounts in the 0.15-0.40
inch range with the greatest amounts over the eastern County Warning Area. Although the
upstream precipitation is mainly rain...forecast soundings wet-bulb zero heights
suggest that the precipitation should change over to mainly snow over Upper
Michigan. There may be a period of rain or sleet until the precipitation
intensity is great enough to lower 900-750 mb temperatures below freezing.
A quick inch or two will be possible over much of Upper Michigan
with slightly greater amounts of 3 to 5 inch possible east of isq-
Seney where the Winter Weather Advisory remains in effect. As the precipitation
intensity diminishes and low level temperatures climb...the lighter precipitation by
middle afternoon should change over to rain or drizzle over the west
half.

In addition...gusty south-southwest winds are expected this morning ahead of the
trough. Even though a 900 mb low level jet over at or above 60 knots is forecast
during the morning...low level stability will be strong enough so
that mixing toward the surface results in more moderate gusts in the 25-
30 miles per hour range. However...locations near the Lake Michigan shoreline
may see gusts to around 40 miles per hour. A period of gusty wrly winds will
also be possible during the late afternoon and evening...especially
over the higher terrain of the Keweenaw...as the stronger
isallobaric component moves through behind the trough. Winds veering
to the northwest will also bring gusty winds to 40 miles per hour near Lake Superior east
of Marquette between 02z-06z.

Late this evening and overnight...some additional light snow/rain
showers may be possible in the moist cyclonic northwest flow around the
departing low as a trailing shortwave moves through during the
evening...especially in northwest upslope flow locations. Expect light snow
showers to diminish overnight as the deeper moisture departs to the
east.

Long term...(monday through saturday)
issued at 411 am EDT sun Mar 29 2015

Synoptic precipitation associated with the system that will move through
today will be east of the County Warning Area by 12z Monday. Thermal trough over the County Warning Area
will allow for some light snow showers on Monday...but dry air will
keep those isolated to scattered. Lots of uncertainty with details
of a shortwave that looks to move nearby late Monday/Monday night. Models
vary in timing...strength and track of the shortwave and associated
surface low...and even small differences in these characteristics makes
for significant forecast differences. The 00z/29 NAM is on the
faster...stronger and farther north end of guidance...which means
greater quantitative precipitation forecast amounts but also more mixed precipitation. On the other
hand...the 00z/29 European model (ecmwf) is weaker and on the southern side of
guidance...meaning only minor precipitation amounts. Certainly potential
for advisory level snowfall in a narrow band...but not at all
confident with where...exactly when and amount of snow.

Should be able to see some light snow showers in northerly flow of Lake
Superior on Tuesday...mainly over ncentral Upper Michigan...but only minor
amounts.

Major changes coming on Wednesday as a stronger system marches along the
US/Canadian border...pulling plenty of warmer air north into the County Warning Area.
850mb temperatures increase to around 10c ahead of a surface trough/cold front
that will move through late Wednesday through Wednesday night. Rain will be
possible in the warm air advection regime ahead of the cold front and also along
the cold front. Winds will also be an issue as S-SW 925mb winds
increase up to 50kts just ahead of the cold front...creating gusty
surface winds. Should be able to get high temperatures into the 50s over the west
half and in the 40s over the east half down wind of Lake Michigan. Low
Wednesday night will be in the 30s to around 40. Rain...warmer
temperatures...greater low level moisture and winds will make for increased
snowpack melting Wednesday/Wednesday night...but no flooding issues are
anticipated as rivers/streams are not elevated.

Thursday through Sat is very uncertain as models are all over the place
with solutions. The European model (ecmwf) wait to move colder air in until a
significant system moves well southeast of the area Friday. The GFS brings a
much colder airmass in on Thursday with some temperature moderate on Sat and no
significant systems. Will lean heavily on consensus guidance Thursday
through Sat.
&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 110 PM EDT sun Mar 29 2015

Look for the precipitation to diminish by late afternoon with the arrival of
larger scale subsidence and the passage of a cold front...allowing
conditions to improve. But gusty west-northwest winds will also folow the front
as the low level instability increases. The arrival of drier low
level air will bring a gradual improvement to VFR this evening at
all sites.
&&

Marine...(for the 4 am Lake Superior forecast issuance)
issued at 524 am EDT sun Mar 29 2015

South southwest gales this morning veering to west and northwest
gales late today and tonight are expected as a strong trough and
upper level disturbance move through the northern lakes. A series of low
pressure troughs Cross Lake Superior through the rest of next
week...but winds are expected to stay mainly below 20 kts.
&&

MQT watches/warnings/advisories...
Upper Michigan...
Winter Weather Advisory until 11 PM EDT this evening for miz007-
014-085.

Lake Superior...
Gale Warning until 5 am EDT Monday for lsz249>251-266-267.

Gale Warning from 5 PM this afternoon to 2 am EDT Monday for
lsz264-265.

Lake Michigan...
Gale Warning until 8 PM EDT this evening for lmz221-248-250.

&&

$$

Short term...jlb
long term...Titus
aviation...07
marine...jlb

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