NWS Gaylord, MI wrote its last area forecast discussion before the first event at May 18, 9:43 AM EST, 2 hours 17 minutes earlier.
Area forecast discussion, May 18, 9:43 AM EST, 2 hours 17 minutes before
Area Forecast Discussion
National Weather Service Gaylord MI
1043 AM EDT Mon May 18 2020
.UPDATE...
Issued at 1036 AM EDT Mon May 18 2020
Widespread rain, at times moderate to heavy, continues to
pinwheel north across much of northern lower Michigan this
morning. Heaviest rain has now mostly centered south of M-72,
where widespread reports of over an inch has fallen since just 6
am this morning. This general idea should continue for the
remainder of the day as low pressure only slow advances south
across central Illinois. Bands of heavier rain will still produce
rainfall rates up to and over a quarter inch per hour at times,
once again especially south of M-72. Another inch or so of rain is
possible in those areas, with amounts steadily tapering off as
one goes north. Deep layer dry easterly flow looks to continue to
keep much of eastern upper dry through this event. All flood
watches and river flood warnings will remain.
&&
.NEAR TERM...(Today through Tonight)
Issued at 606 AM EDT Mon May 18 2020
Impactful weather: Additional high rainfall totals through tonight,
with an ongoing potential for lowland and river flooding. Various
areas of lakeshore flooding from gusty easterly winds and high Lake
levels.
Pattern synopsis and forecast:
An upper level closed low was spinning at the IA/IL border early
this morning, with an associated sfc low pressure over nrn IL/srn
Lake Michigan. Deep moisture with PWATs of 1.25" to 1.50" has been
advected in over nrn Michigan, while low to mid level theta-e
advection, diminishing FGEN, DPVA and pockets of upper divergence
were focused over all of lower Michigan. The resultant pretty
impressive deep layer -divQ and moisture has continued to result in
widespread light to moderate rain. Generally, 1-2" of rain has
already fallen across nrn lower Michigan, with little to none across
eastern upper due a drier easterly low level flow feeding into
there.
The upper level and sfc low pressure will slowly drift SE through
tonight, reaching the Ohio river valley by daybreak Tuesday. Nrn
Michigan will continue to see deep moisture overhead, while several
waves wrap around the upper low and into the area. The forcing from
the theta-e advection, FGEN and upper jet support weaken with time
as it follows the storm system further SE and away from the region.
Thus, our heaviest rainfall is ongoing, and will continue through
today/early this evening, before forecast amounts overnight tonight
are much lighter, and chances for rain start falling off. With the
impressive deep layer -divQ and moisture, nrn lower Michigan is
looking at around a half inch toward the bridge through this
evening, with as much as 2-3 inches south and east of a line from
Houghton Lake to Ossineke. That would likely be the most favorable
place for lowland flooding. Not much information to be had
overnight, so day shift can probably make some phone calls to see if
the rain is causing any significant problems. Will ride the watch
still.
One clue as to maybe a little more confidence that lowland flooding
could end up causing problems, is the latest river forcast for the
Rifle river at Sterling which is expected to rise a little over 3
feet of flood stage, per latest NCRFC river forecast. At the very
least, there will be significant rises on most all nrn lower
rivers and streams.
Highs today will be in the low to mid 50s for nrn lower due to the
thick clouds and rain. Eastern upper under thicker mid and upper
clouds will be able to climb into the upper 50s and lower 60s. Lows
tonight will largely be 45F to 50F.
&&
.SHORT TERM...(Tuesday through Wednesday)
Issued at 606 AM EDT Mon May 18 2020
...The End of the Rain, and a Drying Period...
High Impact Weather Potential...Minimal
Pattern Synopsis/Forecast and possible outcomes...
Tuesday, as the sfc low (and the 500 mb low moves toward the south,
the sfc high to hold position just east of James Bay in Quebec,
pushing low level dry air into the forecast area. As a result, the
QPF begins to diminish pretty quickly. Aloft there is a fair amount
of of dry air as the 500 mb compensating ridge begins to build into
the region from the west and north (one of the reasons that the 500
mb moves south). The SREF is the only model that shows some chances
for rain Tuesday afternoon in NE Lower. However, considering the
amount of dry air and the proximity of the ridges and the drift of
the lows, will dry things out for the afternoon. Tuesday night, the
ridging, both sfc and 500 mb continues, and the dry air really moves
into the region and produces the next several dry days. Wednesday,
as the high moves into New England, there is a little question if
the dry air continues into the region. While the precipitation stays
out of the state, clouds could be on the increase. The GFS is much
more moisture as the SE flow looks to be pushing moisture in from
the remnants of Arthur, while the ECMWF has a much stronger area of
dry air that gets into N Lower, keeping the clouds to the south.
Which scenario sets up what happens in the beginning of the
extended.
.LONG TERM...(Wednesday night through Sunday)
Issued at 606 AM EDT Mon May 18 2020
High Impact Weather Potential...Minimal.
Extended (Thursday through Sunday)...Thursday, the dry air on the
ECMWF and the CMC continues the dry period into Thursday and Friday.
However, the GFS with the extra moisture, also brings the 500 mb low
farther north, which brings the chance of rain back north. The
consensus solution has trended with the CMC/ECMWF idea, so will
continue the dry forecast. The only time that the ECMWF/CMC has rain
is on Saturday, which the GFS has as well. Sunday, looks to be dry
as we get caught between systems and the models begin to show the
next front that will move through the Upper Great Lakes probably
Sunday night/Monday morning. The models have different versions of
front moving through, The GFS has a more solid line, while the ECMWF
and the tail end of the CMC show a broken line.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 606 AM EDT Mon May 18 2020
A low pressure system over northern IL will slowly drop SE into the
Ohio river valley through Tuesday. This system will bring periods of
rain over this time, as well as gusty easterly winds. Despite the
gusty easterly winds, LLWS will be common at all airports for the
TAF period. IFR/MVFR CIGS will impact all airports, with maybe some
improvement at times to low end VFR at PLN tonight. VSBYS will fall
to MVFR at times in the heavier rain, possibly briefly IFR.
&&
.MARINE...
Issued at 606 AM EDT Mon May 18 2020
A low pressure system over northern IL will slowly drop SE into the
Ohio river valley through Tuesday. This system will bring periods of
rain over Lakes Huron and Michigan over this time, as well as gusty
advisory and gale force easterly winds for all nearshore waters
except Whitefish Bay. The gale force winds however, expected to end
by this evening. Drier weather and weakening winds are expected
Tuesday night, as higher pressure moves into the region.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...FLOOD WATCH through this evening for MIZ020>036-041-042.
LAKESHORE FLOOD WARNING until 8 PM EDT this evening for MIZ024-
030-036-042.
LAKESHORE FLOOD ADVISORY until 8 PM EDT this evening for MIZ017-
018-098.
LH...GALE WARNING until 8 PM EDT this evening for LHZ348-349.
SMALL CRAFT ADVISORY until 7 PM EDT Tuesday for LHZ345>347.
LM...SMALL CRAFT ADVISORY until 7 PM EDT Tuesday for LMZ323-341-342-
344>346.
LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ322.
&&
UPDATE...MB
NEAR TERM...SMD
SHORT TERM...JL
LONG TERM...JL
AVIATION...SMD
MARINE...SMD