Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Rapids Michigan
315 PM EDT sun Aug 30 2015

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

Synopsis...
issued at 315 PM EDT sun Aug 30 2015

Much of the upcoming week looks to become very warm and humid across
the region. Much of the time dry conditions look to prevail with
high pressure settling in and no major systems expected to affect
the area. There are some opportunities for an isolated shower or
storm...but these will be very few and far between.

&&

Short term...(this evening through Tuesday night)
issued at 315 PM EDT sun Aug 30 2015

Our main challenges in the short term are fog/stratus potential each
night...and then shower/storm chances for Tuesday.

Clouds have been fairly stubborn to clear out early this afternoon
thus far with a lack of dry air advection into the area...and the
decent thickness of the stratus clouds in place. The clouds are
trying to mix out and become more cellular as the moisture thickness
diminishes. We are also seeing a feature come in from the northwest that
looks to help more with diminishing the cloud cover. We expect more
clearing to take place through middle evening...before clouds start to
reform and some fog develops in the moist air mass and light wind
regime.

We expect the fog and any stratus to mix out a bit quicker on Monday as
it should be much more shallow in nature. We will have a good deal
of subsidence around under the upper ridge which will limit the
vertical extent of any cumulus development. This will allow temperatures to warm
into the middle 80s with h850 temperatures in the middle teens c.

Fog potential Monday night looks to still be possible with dew points
remaining well into the 60s. It should not be as bad as this morning
or what is expected Monday morning. Winds aloft will be a little
stronger keeping things mixed a little better...and the deeper
moisture in place now will have mixed out better on Monday afternoon.

We are still looking at a small chance of a few showers/storms across
the south during the afternoon hours on Tuesday. The models are all
holding on to a weak upper wave across Indiana that was left by the
currently departing upper trough. This is expected to drift north
into the southern portion of the County warning forecast area along with some better moisture on
a srly low level flow. Cape profiles on forecast soundings are rather
limited as are wind fields aloft. Most locations should remain
dry...and any showers/storms will remain weak.

Long term...(wednesday through sunday)
issued at 315 PM EDT sun Aug 30 2015

Much above normal temperatures are expected from middle week through
Labor Day weekend due to a highly amplified upper pattern over the
U.S. Featuring a trough in the west and ridge in the east. The bulk
of the period will be dry however a few isolated diurnal showers or
thunderstorms may develop during peak heating each day.

With little synoptic forcing under the upper ridge... primary
forcing mechanism for any convection would be from mesoscale/Micro scale
effects such as lake breeze convergence.

Humid air mass with dew points in the middle to upper 60s combined with
light winds/stagnant pattern and longer nights will continue to
support the possibility of nighttime fog/stratus.

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 143 PM EDT sun Aug 30 2015

Numerous MVFR ceilings of 1500-2500 feet are expected to linger this
afternoon... followed by more fog and low stratus developing
tonight. Widespread IFR/LIFR ceilings and visibilities are a good bet again
late tonight and Monday morning... especially 08z-14z... with
improvement to MVFR or VFR expected toward 18z Monday.

&&

Marine...
issued at 315 PM EDT sun Aug 30 2015

We are looking at rather benign conditions for much of this week for
marine interests. Winds should remain below 20 knots through the
week...with Monday/Thu-Fri looking like winds could be 10 knots or less
with a very weak gradient in place those days.

We could be looking at some fog issues in the late night/early
morning hours with a moist air mass in place.

&&

Hydrology...
issued at 315 PM EDT sun Aug 30 2015

Hydro concerns are low this week. There small chances for a shower
in any given location during the latter half of the week. Excessive
rainfall is unlikely.

&&

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

$$

Synopsis...njj
short term...njj
long term...Meade
aviation...Meade
hydrology...cas
marine...njj

National Weather Service Glossary of Abbreviations