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Area forecast discussion 
National Weather Service Grand Rapids Michigan
1238 PM EST Monday Nov 30 2015

Latest update...

issued at 327 am EST Monday Nov 30 2015

The area will see a mainly quiet day today with seasonable
temperatures for this time of the year. Late this afternoon and more
so tonight...rain chances will increase across the area ahead of a
storm system to our west. Rain will continue into Tuesday morning
before it ends briefly. Rain showers will then mix with and change
over to some snow showers Tuesday night into Wednesday morning. Some
minor snow accumulations will be possible in grassy areas.

The weather will then quiet down for the remainder of the work
week...and continue into next weekend. Temperatures will warm to
above average levels.


Short term...(today through wednesday)
issued at 327 am EST Monday Nov 30 2015

Our main concerns in the short term are dealing with precipitation timing
initially for late today into tonight...and p-type issues and
amounts for Tuesday night and into Wednesday.

Precipitation should hold off through the daylight hours today for most
areas. Regional radar is somewhat ominous this morning with rain
across north central Illinois already. This precipitation is pretty much heading
straight north for the time being. Model consensus indicates that
the good push of moisture will hold off across the area until after
00z. This will leave the atmosphere rather dry below about 8k feet
through this evening. We can not rule out a shower along the
Lakeshore that might reach the ground with a little light rain...but
this will be the exception rather than the rule.

The bulk of the precipitation will move in by 06z tonight and last through
12z Tuesday before diminishing Tuesday morning. This is when we will see the
best moisture transport at 850 mb move into the area. Forecast soundings
and low level thicknesses would support all rain at the onset with
temperatures likely all remaining above the freezing level.

The rain will move out of the area by Tuesday afternoon for a brief
break in the precipitation. We will see the main jet streak with this system
move overhead Tuesday afternoon...bringing the dry slot in across the
area. We will see breezy conditions develop at that time with very
good mixing taking place in this favorable scenario and with some
possible sunshine.

The break in the precipitation will not be long as the upper low itself will
begin to rotate over the area on Tuesday evening. Precipitation will start out as
rain...and will likely make a transition over to mainly snow late
Tuesday night and Wednesday morning with low level thicknesses falling below
critical thresholds and the cooling of the boundary layer with the
loss of daylight. We will see some lake enhancement as h850
temperatures drop to around -5c producing Delta T/S of around middle
teens with water temperatures around 8-9c. Surface temperatures look hard pressed to get
down below freezing...but some of the grassy areas will see some
possible accums...especially up north.

The precipitation will eventually wind down later in the day on Wednesday. The
upper low is forecast to rotate through the state during the afternoon
hours on Wednesday. The low level winds will switch....limiting lake
enhancement. The main short waves with it will also shift to the
east. We expect that mainly snow showers early in the morning will
at least mix with rain...if not completely change over during the
day with some diurnal heating taking place in the boundary layer.

Long term...(wednesday night through sunday)
issued at 327 am EST Monday Nov 30 2015

Confidence is high that we will have a predominately dry long term
period with above normal temperatures.

Once the upper low pulls away to the east on Wednesday night ridging
and warm advection arrives from the west. Any lingering light
precipitation Wednesday evening will come to an end followed by
decreasing cloudiness.

Heights continue to rise through next weekend and ridging continues
to prevail at the surface. There is no cold air in sight and 800 mb
temperatures remain around 5c. This results is a prolonged stretch of
dry/uneventful weather in southwest Michigan with highs in the middle to
upper 40s and and clear to partly cloudy skies.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1238 PM EST Monday Nov 30 2015

VFR conditions will be maintained into this evening along with an
east wind around 10 knots. The winds will drop off into early/middle

Rain showers will arrive late tonight...toward midnight in the
west (mkg)...and toward daybreak in the east (lan/jxn). This will
cause conditions to lower. However there appears to be enough
mixing that IFR is in question for the western taf sites. At this
point the feeling is that if any IFR occurs it should be
brief...perhaps an hour or two around daybreak. There will be less
wind/mixing in the east and there is higher confidence that lan
and jxn will see a more significant period of IFR Tuesday morning.


issued at 327 am EST Monday Nov 30 2015

Conditions will start out quiet for mariners...and will then
deteriorate late Monday night and especially Tuesday. We are looking
at small craft advisories likely being needed for at least Tuesday...if
not late Monday night. Offshore winds before that time should limit the
wind and wave potential for the nearshore waters. The winds becoming
onshore and cold air coming in will produce some decent wind and
wave potential from Tuesday and beyond.


issued at 1228 PM EST sun Nov 29 2015

Sycamore Creek at Holt has fallen back below there are
currently no river flood advisories in effect. The pere Marquette
river near Scottville continues to rise steadily...but is forecast
to crest slightly below bankfull. Impacts should be minimal.

Additional light rain is expected Monday evening into
Tuesday...followed by lake effect snow late Tuesday into Wednesday.
Precipitation totals should remain around a half inch or less...which would
not have a big impact on river levels.


GRR watches/warnings/advisories...


short term...njj
long term...Meade

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