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Area forecast discussion 
National Weather Service Grand Rapids Michigan
326 am EDT Friday Apr 25 2014

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

Synopsis...
issued at 326 am EDT Friday Apr 25 2014

A frontal system will pass through the area this morning and bring
some light rain to most of the area. Rain should end everywhere by
middle afternoon and some clearing of the clouds should take place.
Most of the weekend should remain dry and approaching average
temperatures. There will be a low chance of rain on Sunday as a
system begins to approach the area. Much of next week looks cool
with numerous chances of rain.

&&

Short term...(today through sunday)
issued at 326 am EDT Friday Apr 25 2014

The short term is looking rather quiet through the day on Sunday.
The most noteworthy items in the short term will be rainfall trends
today...and the chance of rain on sun.

Rain showers are currently in the process of spreading across the
area this morning. This is occurring as the leading edge of a 40
knot low level jet is helping to transport moisture into the area.
The best chance of rain in coming over the next few hours before this
moisture axis weakens and pushes east of the area toward 12z. Better
chance of rain showers will then exist across areas to the south and
east as the deformation zone of the low near St. Louis lifts NE into
the area just before 12z and then moves out before 18z. There will
also be some rrq dynamics helping the cause across northwest Michigan this
morning. We expect to see some clearing move in from west to east
this afternoon.

We expect to stay dry then from tonight through most of the night
Sat night...if not into sun. Some showers will try to approach the
northern areas tonight as the low across the upper Midwest shifts almost
due east across northern lower Michigan and the Upper Peninsula. A cold front
is expected to drop through. We believe that any showers that might
try to develop with this would stay north where the moisture is much
deeper. We will then see upper ridging build in across the area
during the day on Sat and into Sat night.

We continue to expect a low chance of rain during the day on sun across
the SW portion of the area. The upper ridge axis will shift east of
the area by sun...and a lead wave coming out of the SW U.S. Wave
will approach the area. The east/NE flow ahead of this wave will ensure
dry air in the lower levels for the area. Any rain that tries to
move in will have to overcome the quite dry air of 30 degree f T/dew point
depressions. We expect that some sprinkles or a few light rain
showers may reach the ground from the middle levels in the worst case
scenario.

Long term...(sunday night through thursday)
issued at 326 am EDT Friday Apr 25 2014

It would seem southwest lower Michigan is in for a prolonged period
of showers which lasts through the long term period. Some
thunderstorms are possible Tuesday night into Wednesday.
Temperatures will be slightly below normal due to the clouds and
rain.

While rainfall totals through this period may be over an inch...
mostly in the central and southern sections... that rainfall will be
from a prolonged period of showers that will not be particularly
heavy on any one day. As a result Hydro impacts should be limited.

There is generally good model agreement on the overall Patten for
this coming week. That is a closed upper low stalling over the Great
Lakes into at least early Friday. As the system approaches the area
Tuesday into Wednesday southwest Michigan is into the warm advection
sector of the storm. There is a decent low level jet and elevated
instability. So I have continued the threat of thunderstorms we
added on the day shift Thursday. As the system slowly moves east of
the area Thursday southwest Michigan is in the colder northwest flow
but the air is still unstable so showers will continue.

Yesterday I wrote about a strong east Asian jet crossing the
Pacific...into this weekend then developing this system later in the
weekend into early next week over the Western Plains. What is
curious is after this jet core moves on shore the strong flow across
the North Pacific breaks down and what is remains is a series of
wandering closed upper lows between 35n and 45n. That helps explain
why the system stalls near US. There is not much to push it out of
the way.

So the bottom line is periods of showers Monday night through
Thursday and temperatures mostly in the 40s at night and 50s during
the day.

&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 1231 am EDT Friday Apr 25 2014

VFR conditions will continue into the overnight hours. Light rain
will spread in over the next few hours...but ceilings and
visibilities will stay VFR as it will be running into dry air.
There is a window of time between 10z and 18z where some MVFR
conditions are possible. First...via visibility reduction in rain
and then some ceilings that will dip below 3000ft. The rain will
end in the late morning on Friday toward klan and kjxn with clouds
scattering out thereafter. VFR weather is forecast Friday afternoon
and evening. It will turn windy Friday afternoon as northwest winds
of 15 to 25 knots are expected.

&&

Marine...
issued at 326 am EDT Friday Apr 25 2014

We are canceling the Small Craft Advisory with the forecast package
this morning. The core of the winds aloft have peaked across the
area...and will diminish into the morning hours. Winds will tend to
increase some this afternoon...however the Cold Lake waters should
limit the gust potential a bit with winds becoming onshore. We are
watching for the potential for another Small Craft Advisory event
for the day on Sunday.

&&

Hydrology...
issued at 121 PM EDT Thursday Apr 24 2014

Rivers continue to recede and the only site still above bankfull as
of noon Thursday is Evart. It too should fall below bankfull Friday
night or Saturday.

Rain is likely late tonight and early Friday with general amounts of
one tenth to one quarter inch. This will have little impact on the
overall falling trend of the rivers. More showers are likely next
week but no heavy rain is expected at this time.

&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

Synopsis...njj
short term...njj
long term...wdm
aviation...Duke
hydrology...Meade
marine...njj