Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 220213
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
913 PM EST Sat Jan 21 2017

.SYNOPSIS...
Temperatures will remain mild through Monday as low pressure
tracks from the Mississippi valley northeast towards the Mid
Atlantic states. A ridge of high pressure will build across the
region Tuesday into Wednesday. A low pressure system will track
east across the southern Great Lakes Wednesday with more
seasonable temperatures arriving late week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Bumped up pops across NE OH slightly. Expect rainfall amounts to
be on the light side...just a trace to a couple of hundredths of
an inch or rain. With the warm front lingering near the Erie
lakeshore removed mention of fog everywhere except NW OH.

Original discussion...
Precipitation and fog potential overnight are the main concerns in
the forecast. A couple weak mid level impulses will advect northeast
across the area through tomorrow morning. Elevated radar returns
showing up in central Ohio associated with this first impulse have
not been reaching the ground, as soundings show relatively dry
boundary layer. Low level jet centered west of the area this
afternoon will help to moisten the 925-700mb layer. Best shot of
precip will be around and after 06Z as second impulse works toward
the region. For now, kept slight chance of rain showers in the
forecast. Some elevated instability/decent lapse rates could yield a
few isolated thunderstorms, however confidence in precip with weaker
forcing precludes any thunder mention.

Areas of fog are likely to develop after 06-09Z as boundary layer
decouples and winds become light, with a rather strong inversion
forming. Could see some areas of dense fog in the Toledo area and
vicinity, but for now, will hold off on any headlines for dense fog
and just mention areas of fog/patchy dense fog and will monitor this
evening.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
Focus of the short term period is precipitation chances Sunday
through early Tuesday. Upper low will slowly track and deepen from
the lower Mississippi valley Sunday morning to the upper Ohio valley
by Monday afternoon in response to strong southern stream jet
energy. Models are in decent agreement with track/evolution of upper
low and attendant surface reflection. The precip arrival Sunday has
trended a bit slower, with much of the morning/earlier afternoon
possibly dry across the forecast area. Adjusted the forecast to
reflect this trend, with chance pops arriving after 17Z and likely
pops holding off until 21Z and after.

Best window for precipitation, and possible heavy rainfall, will be
Monday morning/early afternoon, especially across the eastern half
of the area where cat pops have been expanded a bit. This is where
best forcing will be present as the upper low tracks along the
Appalachians just east/southeast of the area. Kept QPF amounts Sunday
through Monday night ranging from 0.30" west to around an inch east.
Precip will wind down Monday night/Tuesday morning as the low tracks
eastward off the Atlantic coast. One wild card in the Monday night
time frame is p-type. ECMWF and GFS tend to be on the warmer side
with the low, with perhaps a brief period of changeover to rain/snow
mix late Monday night. The NAM, however, wraps much more colder air
into the low, with p-type changing over much earlier Monday evening,
and perhaps a changeover to all snow overnight, with some
accumulation possible. For now, discounted the NAM and went with a
GFS/ECMWF blend for column temperatures and resultant p-types, with
rain and snow mentioned Monday night. This solution will need to be
watched over the coming model runs and the forecast will be adjusted
accordingly.

High pressure ridge will build across the region Tuesday. This
should yield dry conditions much of Tuesday and Tuesday night.
Northern stream wave will track from the central Rockies toward the
Great Lakes, with precip arriving towards 12Z across the area. P-
types may be in issue, especially NE OH/NW PA high elevations, but
it is too early for specifics other than a cursory rain and snow
mention.

Temperature wise, went a few degrees warmer for highs on Sunday with
slower precip arrival trend, near MAV/EC MOS, but not as warm as MET
MOS. This yields upper 50s/mid 60s across much of the area.
Temperatures will trend cooler Monday through Tuesday, but still
well above seasonal normals.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The long term begins on Wednesday with models in good general
agreement showing an upper over the upper midwest and a general
southwest flow aloft over the area. At the surface, low pressure
will be in SERN MN with a warm front into western Ohio and a cold
front south from the low through Indiana. The low will move
northeast across the Great Lakes dragging both fronts across the
region during the day. Temps will fall behind the cold front
changing rain Wednesday into snow Wednesday night. Thursday 850mb
temps should be around -5C which should keep most precip snow during
the day. Continued with chance pops most places although did keep
likely northeast with flow off the lake for potential lake
enhancement although it would be minimal given temps. No big change
Friday although 850mb temps continue to slowly drop.  Friday night
into saturday another trough rotates across the region bringing
colder air to the region with 850mb temps dropping to -10c and
likely continuing lake effect enhancement northeast.

&&

.AVIATION /00Z Sunday THROUGH Thursday/...
VFR weather continues all areas with mainly mid and high level
cigs. Some showers remain just south and southeast of the area.
The latest guidance including the HRRR has this activity
dissipating by 06z. Will go with a vicinity mention at CAK and YNG
for a few hours. If the precip becomes more imminent we will
update. A strong inversion will develop overnight as cooling
occurs at the surface. This should cause fog and stratus to
develop. Conditions will be the worst in the west...possibly LIFR.
Will develop MVFR cigs all areas around 08z with patchy IFR fog
after that. Will try to improve cigs back to VFR on Sunday morning
with precip holding off till the tail end of the TAF period.

OUTLOOK...Non-VFR developing Saturday night continuing into Monday
in rain. Non-VFR will likely persist on Tuesday across NE OH/NW PA.

&&

.MARINE...
Light south to southeast flow on the lake today through tonight as a
warm front lifts north of the lake. Flow will remain light Sunday as
it turns out of the northeast in response to low pressure moving
through the Tennessee valley. This northeast flow will increase
Sunday night reaching 15 to 20 knots overnight and 20 to 25 knots on
Monday before turning north and dropping back to 10 to 15 knots
overnight Monday night. Winds will increase again from the southwest
Wednesday to 15 to 25 knots as low pressure moves through the
central lakes. Would anticipate small craft headlines will be needed
early Monday into/through Monday night and late Wednesday into
Thursday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...DJB/Greenawalt
SHORT TERM...Greenawalt
LONG TERM...TK
AVIATION...Kubina
MARINE...TK


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