325
FXUS63 KGRR 021630
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1230 PM EDT Sun Jun 2 2024

.KEY MESSAGES...

- Limited chance of showers today through Monday afternoon

- Medium/High Confidence in evolution of upper troughing this week

&&

.UPDATE...
Issued at 1026 AM EDT Sun Jun 2 2024

Latest visible loop shows clearing moving south across the
northwest cwa. Eventually we`ll see the clearing make it south
into Mid Michigan too, but probably not before mid afternoon.
Where the stratus is eroding, cumulus is quickly filling in.
Skies will become partly sunny this afternoon from north to south.
A couple of the CAMs continue to hint out a shower or two possible
over the southeast cwa late this afternoon so we`ll continue with
a very low PoP there.

&&

.DISCUSSION...
Issued at 312 AM EDT Sun Jun 2 2024

- Limited chance of showers today through Monday afternoon

Weak surface low pressure over central lower Michigan early this
morning will shuffle east today. Moisture and clouds in the mid to
upper levels will depart but remain in the low levels for some
portion of the day. Areas of light drizzle may linger this morning
over the middle of lower Michigan. Question will be how quickly does
the low stratus mix and scatter into diurnal cumulus. Latest
guidance more aggressive with sunshine this afternoon near/west of
US-131, while some models including the HRRR leave areas near I-69
relatively gloomy where low level wind convergence and troughing
hangs around a little longer on the backside of the low. Will keep
about a 10 percent chance of measurable rainfall there this
afternoon.

Near-normal temperatures today trend seasonably warm on Monday,
while humidity will be a little more noticeable (dew points near
60). Upper level flow over the northern CONUS through Monday is
fairly zonal but weak, with the next shortwave trough of note
approaching Michigan late Monday. Cirro/alto clouds will be
streaming in on Monday from upstream thunderstorms. The chance of
showers and thunderstorms appears low until late in the day when
better 850 mb moisture streams in and instability increases.

- Medium/High Confidence in evolution of upper troughing this week

Shortwave ridging early this week gives way to height falls by
Tuesday as a closed upper low approaches from the northwest. This low
figures in the evolution of persistent troughing across the Great
Lakes by the end of the week with lower 500 mb heights and low level
northwest flow indicating cooler than normal temperatures into next
weekend.

As far as rain chances, they persist from Monday night through
Wednesday in most southerly flow ahead of the upper low and should
peak on Monday night as a shortwave trough minors out and again
Tuesday night into Wednesday as a cold front will focus rain and
embedded thunderstorms. Showery and cool under the upper low for
late week and the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1230 PM EDT Sun Jun 2 2024

Conditions ranging from IFR to VFR will slowly improve to VFR at
all the terminals this afternoon as cigs gradually improve. VFR
conditions are then expected through the evening. Patchy fog will
develop early Monday morning and bring potential for MVFR/IFR
conditions at times. Any fog will dissipate by mid to late morning
with VFR conditions expected at all the terminals from late
Monday morning into the afternoon.

&&

.MARINE...
Issued at 312 AM EDT Sun Jun 2 2024

Limited potential for hazardous conditions in the nearshore Lake
Michigan waters today and during the day Monday. Some patches of fog
may be present this morning. Winds will be from the northwest and
light today, and a little breezier from the south on Monday.
Thunderstorms may occur over the water between Monday evening and
Wednesday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

UPDATE...04
DISCUSSION...Ostuno/CAS
AVIATION...Laurens
MARINE...CAS