National Weather Service Raw Text Product

Displaying AFOS PIL: AFDGRR Received: 2019-01-12 07:33 UTC


941 
FXUS63 KGRR 120733
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
233 AM EST Sat Jan 12 2019

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 234 AM EST Sat Jan 12 2019

- Winter storm will miss Southwest Lower Michigan to the south.

- Dry weather (no significant precipitation) Sunday into Tuesday

- Not as cold Mon into Wed but colder Thursday

- Possible storm toward next weekend


&&

.DISCUSSION...(Today through next Friday)
Issued at 234 AM EST Sat Jan 12 2019

Overall we are expecting a rather quiet weather pattern through
most of this coming week. The system we thought would go to our 
south today will in fact do that. There is some marginal support 
for some light snow as far north as I-94 but there is so much mid 
level dry air it seems to me this event will largely be a "virga 
storm". Models like the HREF, HRRR, NAM keep the snow south of our
CWA. However the RAP model and about 1/3 of the SREF members do 
bring some snow as far north as I-94. Given the confluent upper 
air pattern over Michigan, it would seem the storm will stay 
south. We do have a very low chance pop over our southern row of 
counties to reflect this low chance of snow. 

Except some flurries over our northeast CWA this afternoon. This
is due to the east winds and 850 temps between -12 and -14c 
coming in from Lake Huron just enough low level moisture we will 
have and east wind lake effect snow shower event over our NE 
counties this afternoon. This will mostly just be flurries through
since the moisture is shallow at best. 

As for the large scale weather pattern we continue to be dominated
by a continued split flow upper air pattern that will continue 
through this coming week. There are some signs of change through, 
the MJO convection has weakened and is in phase 8, which supports 
colder weather here, with a more meridional upper air pattern. To 
that regard the models all support a consolidation for several 
closed upper lows in the Arctic region into one large vortex over 
Hudson Bay that seems to be dropping south late in the week. This
would bring the coldest air of the winter into our area by late 
in the weekend or early in the following week. But here is the 
glitch, most of the models continue to show a strong southern 
stream jet with a quasi-zonal flow. This would suggest the storm 
track would remain south of here and the true cold air would be 
limited. Still this is worth watching over the next few days. 

There is a signal from the ensembles of both the GFS and ECWMF of
a possible snow storm toward the 20th. About 1/2 of the 21 member
GFS ensembles give GRR 3" to 5" of snow from this storm, all but 
2 give us some snow. Similarly about half the ECMWF's 50 members 
give GRR at least 3" of snow from this system. The operational
Canadian model gives as a decent snow storm through with a 994 mb
low tracking over TOL Ohio. At this point my spin would be is that
the system would miss us to the south (as 2 others recently have) due
the strong southern stream jet prevailing. Still it's not out of 
the question and needs to be watched.

One other system to watch is the cold front Wednesday, that may
have some flurries or light snow showers with it. The polar jet
stays well north of here behind that system so even through we do
get some cold air, it's shallow and will likely not result in 
much in the way of Lake Effect snow.


&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1153 PM EST Fri Jan 11 2019

Ceilings will hold steady at 6000-7000 feet at MKG/GRR/LAN 
through the TAF period. At AZO/BTL/JXN, ceilings will decrease
toward 3500 ft by early afternoon. While areas along the 
Indiana/Michigan border will experiencing light snow with 
associated restrictions in visibility and ceiling heights, it
seems AZO/BTL/JXN will remain just north of the light snow with 
VFR conditions prevailing. Should the snow end up tracking over
AZO/BTL/JXN, ceilings and visibilities would drop toward 2000 ft
and 3 miles, respectively. Easterly winds at 5-10 knots will 
prevail at all TAF sites through the forecast period.


&&

.MARINE...
Issued at 234 AM EST Sat Jan 12 2019

Our current surface pattern is not conducive to strong winds over
our near shore waters so it would seem to me we will not be
issuing a Small Craft advisory until Tuesday with the system that
will bring us some cold air later Wednesday into Thursday.



&&

.HYDROLOGY...
Issued at 330 PM EST Wed Jan 9 2019

Water levels are dropping across the area as cold and dry conditions 
have settled into the area. The Maple River at Maple Rapids 
continues to slowly recover from the multiple rain events earlier in 
the month. Water levels are still near bankfull, but will continue 
to drop over the coming days. 

Meanwhile, with the return of cold temperatures, ice production has 
kicked into high gear on many of the streams in the area. A small 
ice jam formed overnight along the Looking Glass River, causing the 
river near Eagle to rise to near bankfull. No flooding was reported, 
and water levels have dropped back down significantly today as 
temperatures have warmed. Additional, likely smaller, ice jams are 
possible each of the next several days as temperatures stay below 
freezing at night. Ice formation is also evident on the Flat River, 
but is not expected to cause any issues at this time.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Borchardt
HYDROLOGY...AMD
MARINE...WDM