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000
FXUS63 KGRR 191936
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
336 PM EDT Fri Apr 19 2024

.KEY MESSAGES...

- Cold stretch; low temps near to below freezing

- Increased fire weather and freeze potential next week

- Chance of showers or storms Tuesday

&&

.DISCUSSION...
Issued at 336 PM EDT Fri Apr 19 2024

- Cold stretch; low temps near to below freezing

Upper troughing/deep cyclonic flow will maintain chilly conditions
over the weekend, with H8 temps bottoming out around -8C Saturday
morning. The incoming air mass is quite dry with dew points
falling into the lower 20s and the main concern is the risk of
freezing temps with blooming vegetation now more vulnerable.

As of today we will begin frost and freeze headlines as necessary
for all but the northern row of counties in the GRR CWFA. See the
latest Public Information Statement (PNSGRR) for more info.

For tonight the risk of a frost/freeze is marginal since the
winds stay up around 10 mph for most of the night plus we may see
some clouds floating in related to a shortwave pivoting in from
the northwest. Given expected low temps mostly 33-35 (inland from
Lk) and any dips to 30-32 more localized/brief, will not issue a
freeze warning tonight. This was coordinated with the DTX office.

After highs only in the mid 40s on Saturday, a better chance for
a freeze exists on Saturday night when winds should be a bit
lighter and guidance temps are a few degrees colder.


- Increased fire weather and freeze potential next week

Fuels (dead or drying live vegetation) will become more prone to
spreading fires as dry and breezy daytime conditions continue into
Sunday and Monday. Sunday may be on the cusp of Red Flag Warning
conditions in mid-Michigan.

On the nighttime side, Sunday night will be another to be on guard
for sub-32 degree temperatures. Just before milder air returns for
Monday and Tuesday, the ridge of surface high pressure will be over
Michigan Sunday night, which should allow winds to go light or calm
under clear skies. This may be a freeze setup that is easier to
mitigate given the calm winds and a sharp temperature inversion
forming in the lowest 100 feet above ground (cold air settling at
ground level with warmer temperatures above).

Wednesday night also has the potential to bring an impactful freeze
with high pressure moving over post-cold-front. The magnitude of the
cold air is still questionable among the model ensembles, as it
depends on whether the core of coldest air from the Hudson Bay
region spills into Michigan or is routed farther to our northeast.

- Chance of showers or storms Tuesday

An upper-level low in the lee of the Canadian Rockies on Monday
opens up into a trough as it progresses east-southeast toward
Michigan on Tuesday. Showers are likely to develop in the vicinity
of a surface cold front. The amount of instability available for
thunderstorms is not settled among the ensembles, but enough for a
mention of a chance of a thunderstorm.


&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 206 PM EDT Fri Apr 19 2024

Gusty west winds to 25 or 30 knots continue through this evening
and relax slightly overnight before becoming gusty again during
the day Saturday. VFR is likely to prevail, though ceilings around
5,000 feet may develop near MKG and north of GRR-LAN this evening.
The HRRR is more aggressive than other models such as the ARW with
bringing ceilings at or below 5,000 feet farther south to AZO-
BTL-JXN by Saturday morning.

&&

.MARINE...
Issued at 336 PM EDT Fri Apr 19 2024

Brisk westerly flow of 15-25 kts and waves 3-6 ft will persist
tonight and Saturday so the Small Craft Advisory has been extended
through the end of the day Saturday. Conditions should fall a bit
below criteria Saturday night but may come up again to advisory
levels on Sunday. Hazardous winds and waves also look possible
Monday through Wednesday as the next weather system impacts the
area.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for LMZ844>849.

&&

$$

DISCUSSION...Meade/CAS
AVIATION...CAS
MARINE...Meade