Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 282313
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
713 PM EDT Tue Mar 28 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 329 PM EDT Tue Mar 28 2017

Fair weather is expected through the day Wednesday. Low pressure
will approach Lower Michigan on Thursday. A brief period of
wintry precipitation could start the day for locations along and
north of I-96. Precipitation will transition to a soaking rain
during the day Thursday. Conditions are expected to trend drier
through next weekend with the possibility for more active weather
at the beginning of next week.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 329 PM EDT Tue Mar 28 2017

The main event in the short term will be the system that moves in
late Wednesday and Thursday. This brings the potential for another
round of soaking rainfall with the onset possibly starting as a bit
of wintry precipitation.

Our next potentially big rain event can be seen churning over the
southwest, resulting in thunderstorms over the panhandle of Texas
and Oklahoma. The closed upper low will swing our direction as it
transitions into a pretty decent shortwave feature.

The initial question with this system is how soon precipitation
begins. Mid and upper level moisture and lift increases along a
boundary that extends well out ahead of the system late Wednesday
night. Guidance continues to point out a dry layer (below 8k feet)
persisting into early Thursday morning across portions of
southern Lower Michigan. At this point, it seems this layer is
more pronounced along and south of I-96. This is where the onset
of precipitation may be delayed for a couple of hours, if trends
continue in this direction. Where the boundary lines up, this
layer may be overcome a little quicker. Precipitation may hold off
until after midnight for most locations.

Temperature profiles would suggest the first few hours starting as
snow across central Lower Michigan with a transition line
progressing from southwest to Northwest Thursday morning. Areas
along and south of I-94 are likely to be all rain with the best
chances for wintry precipitation along/north of I-96. As milder
air takes over, all precipitation turns to rain, which could be a
soaker. Models diverge on where the heaviest rain fall, but
rainfall totals may push/exceed one inch in some locations.

Between now and Thursday, we will see fair weather. Dry air will
continue to gradually work out the cloud cover overhead from north
to south. Wednesday will begin with some sunshine, before clouds
increase during the afternoon.

.LONG TERM...(Friday through Tuesday)
Issued at 329 PM EDT Tue Mar 28 2017

Precipitation chances were increased Monday night, but overall
forecast certainty for the whole period is poor. This will make
subsequent forecasts very susceptible to change.

The weekend is looking drier than what yesterday`s forecast
indicated. As suspected, there will be too little moisture to
capitalize on a minor upper PV maximum forecast to drop southeast
across the area around this time. Models have been surprisingly
consistent with this PV feature, but I am reminding myself that this
is a day 4 to 5 forecast through a prolonged pattern of weak and
unphased upper flow over the CONUS - far from ideal regarding
predictability.

Keeping this backdrop of uncertainty in mind, we are looking at
precipitation potential early next week. Our forecast will feature
>50% PoPs Monday night primarily across the southeastern forecast
area. This is a pretty aggressive this far out for reasons already
mentioned. It is based primarily on the wet deterministic GFS and
ECMWF solutions. The 00Z GEFS and ECMWF ensemble members
unsurprisingly show a very wide range of solutions regarding the
track of the surface low and associated precipitation. So,
we will continue to expect more fluctuations in subsequent forecasts.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 712 PM EDT Tue Mar 28 2017

The clearing line was moving south across the I-94 TAF sites early
this evening. This will produce VFR conditions at all sites by
00-01Z. The VFR will be maintained for the rest of this TAF
period. ENE winds will increase to around 10 knots by early to mid
afternoon on Wed.

&&

.MARINE...
Issued at 329 PM EDT Tue Mar 28 2017

Wave are expected to remain less than 3 feet for the remainder of
the week. No headlines are warranted in the period.


&&

.HYDROLOGY...
Issued at 320 PM EDT Mon Mar 27 2017

Most rivers have demonstrated within bank rises after rainfall over
the last 4 days. However, more elevated river levels at Ionia,
Hastings, Eagle, and Holt may be susceptible to additional rainfall
expected Thursday and Friday, possibly another 0.50"-1.00". This may
act to provide secondary river crests heading into the end of the
week and weekend, potentially higher than the current crests.

&&

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

$$

SYNOPSIS...JAM
SHORT TERM...JAM
LONG TERM...TJT
AVIATION...JK
HYDROLOGY...Hoving
MARINE...JAM



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.