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Area forecast discussion 
National Weather Service Grand Rapids Michigan
327 PM EST Thursday Jan 29 2015

Latest update...
synopsis/short term/long term

issued at 312 PM EST Thursday Jan 29 2015

Low pressure will track eastward away from the region tonight taking
most of the precipitation with it. Cold high pressure will build in
for Friday leading to mainly dry conditions. A cold front will
weaken as it tracks through lower Michigan Saturday. Low pressure
will then track up the Ohio Valley for Sunday. This system could
bring some snow to southern parts of lower Michigan.


Short term...(this evening through Saturday night)
issued at 312 PM EST Thursday Jan 29 2015

The main challenge in the short term deals with whether to extend
the headlines this evening.

Temperatures have been climbing and most locations are near or above
freezing. The precipitation has been weakening. Colder cloud tops
were pushing east of Lansing supporting not much additional
precipitation from this system what does fall should be mostly
snow...except some rain could mix in around Interstate 94. There
enough warmth in the low levels exists to allow for melting. Also
speeds on the Highway are close to normal...suggesting the impact
has diminished from the earlier snow and freezing rain. As a result
of all this the Winter Weather Advisory will be cancelled slightly

Northerly cold air advection sets up overnight and that could will
support some lake effect as the colder air moves in. This setup
looks weak. The dgz is shown to be moist...but subsidence is
noted. This will act to keep the potential for accumulations low. I
will feature highest probability of precipitation along the Lakeshore.

The surface high drifts over the area Friday night. Given the cold
airmass in place...with light winds and at least limited clouds to
start the night...temperatures will end up as a well below

Warm air advection develops Saturday. This could lead to lake
effect/enhanced snow as the flow turns southwest. The timing of
the arrival of the middle level moisture does not coincide with the
increasing low level moisture. Thus only a limited chance for snow
exists. If this moisture becomes aligned...a better shot for
accumulating snow could exist Saturday. There is some Omega shown
in the low level moisture Saturday while the dgz is unsaturated.
Will need to monitor the freezing drizzle risk with later

Long term...(sunday through thursday)
issued at 312 PM EST Thursday Jan 29 2015

The storm on Sunday moves through the Ohio Valley and we will
continue to watch for the potential of the northern shield of snow
as it looks to just graze Southern Lower Michigan. Cold and dry
northeast flow should help erode the clouds and clearing Sunday
night will bring lows in the 5 below to 5 above range Monday morning.

Surface ridge moves east on Monday and onshore flow will bring some lake
effect snow showers inland but inversion heights around 5 kft will
limit accums.

A clipper along an Arctic front arrives late Tuesday into Tuesday
night and lake enhancement in southwest flow should help bring
widespread accumulating snow with a few inches in the area of best
low level convergence across western and central zones. Very cold
air arrives for Wednesday with lake effect snow showers in northwest
flow bringing light accums into Thursday when surface ridging lowers
inversion heights below 3 kft. Thursday is also prognosticated to have the
core of the cold air moving in with 850 mb temperatures down to minus 25c.


Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 120 PM EST Thursday Jan 29 2015

IFR conditions should improve to MVFR as light snow will be ending
by late afternoon except near Lake Michigan where some snow showers
will be possible into this evening. Then expect MVFR conditions to
prevail overnight as a stratus deck with bases around 2500 feet
above ground level persists into Friday morning. Northeast winds will gust over
20 knots at times.


issued at 1107 am EST Thursday Jan 29 2015

Little precipitation fell overnight into this morning. Only minor
additional precipitation is anticipated through the remainder of
the week. Maximum temperatures will vary from day to day through
the weekend before much colder air moves in early next week.
Overall temperatures will be near or below normal to support ice
build up on rivers. Rivers should remain stable into next week.


GRR watches/warnings/advisories...


short term...mjs
long term...ostuno

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