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Office: CLE

FXUS61 KCLE 211017
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
617 AM EDT Tue Aug 21 2018

.SYNOPSIS...
Low pressure over northern Illinois will move northeast across
the central Great Lakes today. The first of tow cold fronts
associated with the low will track east across the region early
today. A stronger cold front will drop across the area tonight
into early Wednesday. High pressure will build east into the
Ohio Valley on Thursday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Update...No changes.

Original...Surface low over northern IL will move northeast
across the central Great Lakes today. A warm front will move
north across the region in the early morning hours today
followed quickly by a cold front. This first front is more
pacific in nature with no big cool down immediately in its wake.
Meanwhile high pressure will drop southeast across the northern
plains. This will help the low tap a reinforcing shot of cold
air that will move into the region tonight and early Wednesday.
For today warm frontal precip now occurring across the region
and should lift north with the front this morning. Do expect
showers and thunderstorms to again move into the area from the
west with the first cold front later this morning and early
afternoon. Given timing and available energy/shear, eastern OH
nwrn PA remain outlooked for a slight chance of severe. Precip
should tapper west to east overnight tonight however as colder
air moves across the lake expecting showers and possibly a
little thunder to hang on into Wednesday in (roughly) the
"snowbelt". Highs today upper 70s to near 80. Highs Wednesday
lower 70s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
A large amplitude ridge over the western three quarters of the lower
48 states will shift gradually east to push an upper level trough
out of the local area by Thursday morning.  The upper level ridge
will dominate the local area through Friday when a fast moving
shortwave trough and associated positive vorticity maximum move east
across the Great Lakes region.  This system will bring with it some
limited moisture.  A weak wave of surface low pressure associated
with this upper level trough will move through the area as well.
Cold air advection will take place Wednesday night through Friday
well in advance of the next low pressure system. The surface low
will force a warm front northeast across the area Friday night
ushering in much warmer air just in time for the weekend. The
combined features will bring a threat for showers and thunderstorms
Friday night to the local area.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
Upper level shortwave trough will push east of the area Saturday as
mean upper level flow tries to go zonal across the lower 48 states.
Meanwhile, upper level trough moves east into the west coast by
Saturday causing a slight ridging to occur over the rest of the
country into the eastern United States.  Upper level ridge parked
over the southeastern states will wash out the west coast trough
initially.  Then, a much stronger trough dives east into the western
states causing the eastern ridge to amplify by Monday.  This will
continue to push some very warm air northeast into the forecast area
during this period.  As the low pressure system at the surface moves
east of the area, a trailing cold front will push east into the area
Monday where it appears to go nearly stationary.  Moisture along the
front will help support at least a threat for showers and
thunderstorms through the weekend; albeit minimal until at least
Monday as the front approaches.  Warm air advection will continue in
earnest through the period.  Muggy conditions will persist as well
as dewpoint temperatures making the climb back into the lower 70s
over the weekend.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
Surface low over northern IL early today with moist southerly
flow into northern OH. Radar showing showers and embedded
thunder moving nne into northeast OH and will eventually reach
into nwrn PA as well. Another area of showers/thunder will
similarly move into northwestern OH affecting KFDY and KTOL
terminals through the next couple hours. After that, it becomes
difficult to pin down individual areas of precip/thunder but
showers and thunderstorms should be expected across the region
much of the period as the low moves northeast across the central
Great Lakes through the day. Am expecting VFR CIGS to lower to
MVFR around sunrise then lift through the morning back to VFR
however any showers/thunderstorms will yield MVFR or IFR
conditions.

OUTLOOK...Non-VFR possible in showers and thunderstorms
Tuesday night into early Wednesday. Non-VFR possible Saturday.

&&

.MARINE...
Small craft advisory flags will continue to fly off Erie county in
Pennsylvania through the duration of the day today.  Downslope winds
over that area could help accelerate the winds and force minimal
small craft conditions.  Flow out of the south will gradually shift
around to a southwest direction today and will likely need to expand
the small craft advisory for much of the nearshore waters by late
this afternoon into the evening.  Then, flow becomes northwest and
winds should remain strong enough for small craft conditions through
tomorrow at least. Winds begin to diminish Thursday and will remain
light 10 knots or less through Friday.  A southerly flow develops at
15 to 25 knots by late Friday night over the lake and this will
continue through the day Saturday.

Waterspouts are a possibility Wednesday morning in any residual
showers. Cold air aloft will help support the instability to produce
the waterspout potential. So will mention threat in the morning.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for LEZ149.

&&

$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...Lombardy
LONG TERM...Lombardy
AVIATION...TK
MARINE...Lombardy

FXUS61 KCLE 211049
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
649 AM EDT Tue Aug 21 2018

.SYNOPSIS...
Low pressure over northern Illinois will move northeast across
the central Great Lakes today. The first of tow cold fronts
associated with the low will track east across the region early
today. A stronger cold front will drop across the area tonight
into early Wednesday. High pressure will build east into the
Ohio Valley on Thursday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Update...No changes.

Original...Surface low over northern IL will move northeast
across the central Great Lakes today. A warm front will move
north across the region in the early morning hours today
followed quickly by a cold front. This first front is more
pacific in nature with no big cool down immediately in its wake.
Meanwhile high pressure will drop southeast across the northern
plains. This will help the low tap a reinforcing shot of cold
air that will move into the region tonight and early Wednesday.
For today warm frontal precip now occurring across the region
and should lift north with the front this morning. Do expect
showers and thunderstorms to again move into the area from the
west with the first cold front later this morning and early
afternoon. Given timing and available energy/shear, eastern OH
nwrn PA remain outlooked for a slight chance of severe. Precip
should tapper west to east overnight tonight however as colder
air moves across the lake expecting showers and possibly a
little thunder to hang on into Wednesday in (roughly) the
"snowbelt". Highs today upper 70s to near 80. Highs Wednesday
lower 70s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
A large amplitude ridge over the western three quarters of the lower
48 states will shift gradually east to push an upper level trough
out of the local area by Thursday morning.  The upper level ridge
will dominate the local area through Friday when a fast moving
shortwave trough and associated positive vorticity maximum move east
across the Great Lakes region.  This system will bring with it some
limited moisture.  A weak wave of surface low pressure associated
with this upper level trough will move through the area as well.
Cold air advection will take place Wednesday night through Friday
well in advance of the next low pressure system. The surface low
will force a warm front northeast across the area Friday night
ushering in much warmer air just in time for the weekend. The
combined features will bring a threat for showers and thunderstorms
Friday night to the local area.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
Upper level shortwave trough will push east of the area Saturday as
mean upper level flow tries to go zonal across the lower 48 states.
Meanwhile, upper level trough moves east into the west coast by
Saturday causing a slight ridging to occur over the rest of the
country into the eastern United States.  Upper level ridge parked
over the southeastern states will wash out the west coast trough
initially.  Then, a much stronger trough dives east into the western
states causing the eastern ridge to amplify by Monday.  This will
continue to push some very warm air northeast into the forecast area
during this period.  As the low pressure system at the surface moves
east of the area, a trailing cold front will push east into the area
Monday where it appears to go nearly stationary.  Moisture along the
front will help support at least a threat for showers and
thunderstorms through the weekend; albeit minimal until at least
Monday as the front approaches.  Warm air advection will continue in
earnest through the period.  Muggy conditions will persist as well
as dewpoint temperatures making the climb back into the lower 70s
over the weekend.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Surface low over southern Lake Michigan early today with moist
southerly flow into northern OH. Radar showing showers and
embedded thunder moving nne into northeast OH and nwrn PA.
Another area of showers/thunder is in northwestern OH affecting
KFDY and KTOL terminals. Through the day still will be
difficult to pin down individual areas of precip/thunder but
do expect showers and thunderstorms to be across the region
much of the period as the low moves northeast across the central
Great Lakes through the day. Am expecting widespread MVFR CIGS
to start with MVFR/IFR conditions within showers and
thunderstorms. CIGS should lift to a low VFR this afternoon.
Will continue with thunder in tempo groups central and east into
the afternoon and then back down to VCTS mid/late afternoon.

OUTLOOK...Non-VFR possible in showers and thunderstorms early
Wednesday. Non-VFR possible Saturday.

&&

.MARINE...
Small craft advisory flags will continue to fly off Erie county in
Pennsylvania through the duration of the day today.  Downslope winds
over that area could help accelerate the winds and force minimal
small craft conditions.  Flow out of the south will gradually shift
around to a southwest direction today and will likely need to expand
the small craft advisory for much of the nearshore waters by late
this afternoon into the evening.  Then, flow becomes northwest and
winds should remain strong enough for small craft conditions through
tomorrow at least. Winds begin to diminish Thursday and will remain
light 10 knots or less through Friday.  A southerly flow develops at
15 to 25 knots by late Friday night over the lake and this will
continue through the day Saturday.

Waterspouts are a possibility Wednesday morning in any residual
showers. Cold air aloft will help support the instability to produce
the waterspout potential. So will mention threat in the morning.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for LEZ149.

&&

$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...Lombardy
LONG TERM...Lombardy
AVIATION...TK
MARINE...Lombardy



Office: ILN FXUS61 KILN 211054 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 654 AM EDT Tue Aug 21 2018 .SYNOPSIS... A surface low pressure will track northeast from the mid Mississippi Valley across the Great Lakes today. As this occurs, a cold front will move east across the area. This will cause scattered showers and thunderstorms. In the wake of the cold front, a much cooler and more comfortable airmass will move into the area, bringing dry weather through the remainder of the work week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... H5 shortwave will swing east across the southern Great Lakes/ Ohio Valley today. In association with the s/w a sfc low and cold front will also work east. Latest mesoscale models are suggesting that the convection lifting north thru Kentucky will expand a little as it lifts through early this morning, but that behind it, a good chunk of the fa could be dry for the morning hours. By afternoon, expect convection to redevelop as CAPES reach 1500-2000 J/kg. Went with the higher PoPs in the east for today, This is also were there is a better chance of an isolated strong to severe thunderstorms this afternoon. Kept the skies cloudy today, this will keep highs in the upper 70s in the northwest and the lower 80s in the southeast. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... By 00Z Wednesday the axis of the H5 trof will be east of the region. However, a secondary front/trof will pivot through the area this evening. This will keep a chance of some showers and perhaps a thunderstorm with the marginal instability over the area. Drier air will begin to pushing in after midnight but the clouds will be slow to erode. Expect lows to range from the lower 60s in the northwest to the mid 60s southeast. By Wednesday morning, the region will be under northwest flow aloft. The region will just be begin to feel the affects of surface high pressure which will be centered over the central plains. A small chance of precipitation will be lingering in the southeast counties, but it will only last for a few hours in the morning. Clouds will be on the decrease through out the day and temperatures will be below normal, ranging from the lower 70s in the north to the upper 70s across nrn KY. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... The long term portion of the forecast continues to depict a touch of early autumn at the outset, returning to mid-summer heat and humidity by the end the upcoming weekend, and through much of next of next week as a high confidence synoptic signal is present in the long range deterministic and ensemble suite of data. Starting 00Z Thursday, anomalous longwave trough over the eastern CONUS will be shifting slowly east with large pool of negative 925mb/850mb temp anomalies. With 1020mb surface high set to follow on the backside of this trough, several days very un-summer-like temperatures and humidity are in store for the Ohio Valley, particularly Wed night/Thur/Thur night where overnight minimums will drop well into the 50s and daytime highs solidly in the low to mid 70s under ample sunshine. This is a very mid-late September weather regime for the end of the work week. On Friday/Friday night, several key changes will begin. A large Rex Block feature off the west coast of the U.S. will really become entrenched...with high latitude and very strong mid/upper level ridge over the northern Pacific. This will in turn force a weakness and eventual deepening /trough/ in the height field over the wrn CONUS and in particular the Pacific NW. In response to this, heights over the eastern CONUS will begin to dramatically rise as subtropical ridging becomes dominant across the southern 2/3rds of the eastern U.S. A migratory shortwave trough spreading east through the northern tier of the U.S. on Friday will begin to deamplify as it runs into the burgeoning ridge in the east. Per the latest 20.12Z ECMWF ensemble and deterministic runs of the GFS/ECMWF/CMC, this shortwave will bring a rapid and significant low level moisture flux to the Ohio Valley in the wake of the departing high, despite much of the larger scale forcing starting to glance off to the north as the shortwave decays. Precipitable water and boundary layer dewpoints will very rapidly return to above normal values by Friday night into Saturday with increasing southwesterly flow ahead of the wave. This should be enough to carry a shower or thunderstorm complex or two into or through the ILN CWA sometime later Friday night and/or into Saturday. Rain chances were raised a little in this timeframe into the ~40 percent range. Height rises will continue Saturday/Sunday/Monday as the very stable longwave pattern becomes entrenched over the Pacific/North America, featuring the Rex Block in the Pacific and anomalous subtropical ridge across the southeast half of the CONUS. The ILN CWA will eventually become centered under the core of 700mb/500mb standardized height anomalies /+1.5 sigma/ by early next week, and attendant to this will be +1.0 to +1.5 sigma 850mb temps - which pretty much guarantees a long-duration period of sticky late summer heat with daily highs in the upper 80s to around 90, and overnight lows in the lower 70s, especially considering PWAT anomalies 1.5 to 2.0 sigma above climo. This pattern will extend well beyond Monday, likely remaining entrenched into the middle/end of next week. Once this pattern really takes hold /Sunday/ rain chances are never really gone but synoptic forcing signals become very muted. The 20.12Z CIPS Analogs for the GEFS pattern shows a likely MCS corridor on the southern fringe of the westerlies which are displaced well to the north, and these MCSs are likely to develop at the inflection of the subtropical ridge and positive tilt nature of the longwave western trough. This would be in the MN/WI area and storms riding southeast into MI or nrn OH dropping into the feed of hot/unstable/high PWAT air over the southern Great Lakes. So in addition to probably dealing with some late August heat indices in the mid 90s, other threats going into next week may a pattern of repeat 'ridge rider' MCS complexes into the northern CWA which is depicted very well by the CIPS Analog threat plots. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Scattered convection continues to work north through mainly the northern and eastern tafs early this morning, while a dry slot is working into the southwest. There is some areas of MVFR cigs in the western tafs. A sfc low out over northern Indiana will move eastward this morning pushing a cold front east through the region. Mesoscale models continue to indicate that the dry slot will dominate the I-71 corridor this morning, with some scattered convection on the nw and se periphery. All cigs are forecast to reach VFR by late morning. Convective coverage is expected to gradually increase during the afternoon as heating increasing. Winds will increase today, gusting to around 20 kts by mid morning. Bulk of the pcpn will be pushed to the east by 00Z, but a secondary front/trof axis moving southeast through the region could cause a shower or storm in the east until about 03Z. Models are indicating that an MVFR deck will aft 06Z and will last through mid morning Wednesday before starting to scatter out. OUTLOOK...MVFR ceilings possible Wednesday morning. Thunderstorms possible Saturday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR/Sites NEAR TERM...Sites SHORT TERM...Sites LONG TERM...Binau AVIATION...Sites