FXUS63 KGRR 312315

Area Forecast Discussion
National Weather Service Grand Rapids MI
715 PM EDT Sun May 31 2020


Issued at 330 PM EDT Sun May 31 2020

- Cool through Monday then warmer

- Chance of storms Monday night and Tuesday night into Wednesday


.DISCUSSION...(Today through next Saturday)
Issued at 330 PM EDT Sun May 31 2020

- Cool through Monday then warmer -

Fair and seasonably cool wx will continue through Monday with
high pressure still in control. It will not be quite as cool
tonight as last night as some high clouds will move in from
the nw overnight. Low temps will range from the lower to middle

High temps Monday will reach the upper 60`s to lower 70`s
with some sun and southwest winds on the back side of the
departing ridge. Latest numerical guidance numbers and ensembles
continue to indicate it will be milder mid to late week with
high temps in the upper 70`s to lower 80`s as a rather zonal
upper level pattern develops.

- Chance of storms Monday night and Tuesday night into Wednesday -

A warm front will focus development of showers and a few storms
Monday evening as elevated instability increases. A few showers
may develop as early as Monday afternoon. A consensus of latest
CAMs suggests weak convection may develop Monday evening with the
increase in elevated instability. The thickness pattern and CAMs
suggest the storms will move to the southeast Monday night.
No severe wx is expected.

A weak cold front will bring potentially surface based storms
Tuesday night. A few locally stronger storms are possible with
potential for moderate sfc based instability out ahead of the
front and increasing deep layer shear.

However the overall severe wx threat is rather low given unfavorable
cold frontal timing and decreasing sfc based instability late
Tuesday night. A consensus of sref fcst svr wx parameters and
frontal timing favors areas well off to our west for severe wx Tue.
Fair wx will return for late week with seasonably warm conditions.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 710 PM EDT Sun May 31 2020

A relatively dry airmass will persist into Monday keep the risk
for impacts low. Later Monday afternoon...there is a risk for
thunderstorms to track in from the northwest. These storms may
weaken as they move into the TAF sites toward the end of the
period. We will need to monitor trends though in the event they
hold together longer than expected. The south to southwest wind
will increase as the storms/showers move in.


Issued at 330 PM EDT Sun May 31 2020

Winds and waves will likely become hazardous to small craft
late Monday afternoon through Tuesday morning. Thunderstorms will
pose a hazard to mariners Monday night and again Tuesday night.





NWS GRR Office Area Forecast Discussion