Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/22/20
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
1039 PM EDT Mon Sep 21 2020
.SYNOPSIS...
Strong high pressure will build into the region from the north
overnight. This high will stay over the region through midweek
before pushing offshore into next weekend.
&&
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
As of 940 PM EDT Monday...
Latest analysis reveals strong (~1034mb) sfc high pressure
centered from New England to the Mid-Atlantic region. Offshore,
Hurricane Teddy continues to move nwd NE of Bermuda and has
picked up forward speed. The gradient between the surface high
and Teddy offshore continues to result in breezy conditions near
the immediate coast, but winds are now light/calm inland as the
high continues to build in. IR satellite imagery continues to
show ocean effect SC hanging on across SE VA/NE NC. Elsewhere,
skies are mainly clear. The clouds over SE VA/NE NC are expected
to slowly dissipate tonight from NNW to SSE, but will likely
hang on for the majority of the night (especially from VA Beach
to coastal NE NC).
High pressure continues to build over the area tonight, finally
allowing the pressure gradient to relax a bit more into
midweek. This will also result in excellent radiational cooling
conditions, especially over inland areas. Clearing and cold
relative to late September. Lows mainly in the upper 30s out
along the VA-15 corridor from FVX-LKU...low to mid 40s for
most...with mid-upper 50s across coastal SE VA/NE NC.
&&
.SHORT TERM /8 AM TUESDAY MORNING THROUGH THURSDAY/...
As of 310 PM EDT Monday...
Another pleasant early Fall day across the region...appropriate
with the Autumnal Equinox tomorrow. Building upper ridging/sfc
high overhead brings a mostly clear/sunny sky with low humidity
levels and highs in the low 70s. Not quite as cool Tuesday night
with lows in the mid to upper 40s and low 50s along the coast.
Sfc high slides offshore and the upper ridge finally starts to
break down as remnants of TC Beta start to push across the mid-
south region. Resultant return flow will kick start moderating
trend with temps bumping back up toward climo normal. Highs Wed
in the upper 70s to ~80. Did nudge up sky cover for Wednesday
and Thursday, with HRRR Smoke cross section starting to indicate
some thin smoke making its way back into the region on building
W-NW flow aloft. Remaining dry with early morning lows
Wednesday in the low to mid 50s inland to right around 60
degrees at the immediate coast.
Dry wx continues on Thursday. Do expect more in the way of
clouds, owing to an approaching upper trough...and additional
remnant energy from Beta...lifting across the Mid-South region.
Some models do start to indicate some very low PoP Thu aftn, but
given antecedent dry airmass, will hold PoP off until Thu night
at the earliest. Highs Thursday ranging through the 70s, near
80 across NE NC.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 310 PM EDT Sunday...
Previously referenced shortwave trough pushes across late
Thursday into Friday, allowing for scattered showers across the
area (20-35% PoPs) through Friday, with best chances along and
south of US-460 given latest information. Weak ridge of high
pressure begins to develop by Saturday over the region ahead of
a deepening trough to the west. The ridge and trough deepen
through the weekend and into Monday as a low pressure system
develops over the Great Lakes. The trough and associated cold
front moves through the region Monday or Tuesday. The result of
this amplified pattern will be an increase in at least
isolated/widely scattered prefrontal precipitation chances from
Saturday through at least Monday.
Highs generally in the upper 70s to around 80F through the extended.
Lows Wednesday night will range from the low 50s NW to around 60F
near the coast. Lows Thursday through Saturday nights will range
from the mid to upper 50s W to the low 60s E. Lows Sunday night will
range from the low 60s NW to the upper 60s SE.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 740 PM EDT Monday...
VFR conditions across area terminals are expected to continue
through the 00z TAF period. SCT-BKN ocean effect SC (~4-5kft
AGL) over PHF/ORF/ECG will slowly diminish from NNW to SSE
overnight, giving way to SKC conditions at all of the terminals
by no later than 12z as high pressure builds toward the local
area. Mainly SKC conditions are then expected to prevail
through the remainder of the 00z TAF period. Gusty NNE winds (to
~20 kt) at ORF/ECG will turn to the N-NNW and diminish slightly
by early Thu AM. Winds are forecast to remain below 10 kt at
the other terminals through 12z. Winds turn to the NW during the
day on Tue and are expected to be around 10 kt. A few gusts to
15-20 kt cannot be ruled out near the coast (highest gusts on
Tue will likely be at SBY).
OUTLOOK...Strong high pressure will provide dry/VFR conditions
through midweek.
&&
.MARINE...
As of 300 PM EDT Monday...
The surface high pressure that has been producing the strong NE
winds is beginning to weaken over New England this afternoon,
allowing winds to come down slightly this afternoon. Winds
remain NE but now most sites are reporting around 15 kt with
gusts 20-23 kt. The Gale Warning for coastal waters off
Currituck County was allowed to expire earlier this afternoon.
Winds south of Cape Henry are 20-25 kt with a few gusts up to 30
kt. Winds across area coastal waters will continue to decrease
into the evening. The surface high pressure over New England
will slide southwest into the Mid-Atlantic tonight and into
Tuesday. Winds will turn north overnight and into Tuesday
morning and be 15-20 kt.
Therefore, SCAs for the Bay and Currituck Sound have been
extended through 15z/11am Tuesday, and remain at 09z/5am
Tuesday for the lower James, and 22z/6pm today for the
remaining rivers. The combination of onshore flow and Hurricane
Teddy will result in seas remaining 8-12ft through tonight and
subsiding to 6-10ft Tuesday, with 5-7ft waves in the mouth of
the Bay today subsiding to 3-4ft Tuesday. SCAs for the ocean N
of the VA/NC border have been extended through 11z/7am
Wednesday, and remain 22z/6pm Tuesday for the mouth of the Bay.
Hurricane Teddy is forecast to make landfall in Nova Scotia
early Wednesday. The wind will become WNW 10-15kt across the bay
and 15-20 kt across the ocean. Seas are expected to subside
once the hurricane makes landfall and the wind becomes offshore.
High pressure then slides offshore later in the week with the
wind becoming southerly. Seas are expected to subside to ~2ft by
the end of the week.
&&
.HYDROLOGY...
As of 740 PM EDT Monday...
Flood Warnings remain in effect for the Nottoway River near
Sebrell and the Blackwater River near Franklin. Flood Warnings
will likely will remain in effect for at least the next day or
two at these sites.
See FLWAKQ/FLSAKQ and weather.gov/AKQ for more site-specific
information.
&&
.TIDES/COASTAL FLOODING...
As of 955 PM EDT Monday...
Have extended the Coastal Flood Advisory for the northern Neck
through the upcoming high tide cycle overnight/early Tue AM for
minor flooding at Lewisetta. Allowed the Bay side of the MD
eastern shore to expire as water levels are expected to fall
just shy of minor flood early Tue AM. Also raised a new Coastal
Flood Advisory for Currituck/Va Beach/Norfolk/Chesapeake through
the upcoming high tide cycle. If departures are slow to fall on
Tue, additional advisories may be needed into early aftn but
will allow next shift to evaluate how the departures verify w/
the upcoming tide before extending the headlines.
The flood tide from this aftn was higher/stronger than forecast
by CBOFs (was almost 2.0 kt) so we will see how that potentially
affects the water levels in the Bay during the next 12 hrs
(possibly keeping them higher than model forecasts). The ebb
tide right now at the mouth of the Chesapeake Bay is averaging 1
to 1.5 kt so some water will get out and am not expecting a
major increase in anomalies over the Bay, rather that they will
not fall as rapidly as the models from earlier today were
forecasting. This could have implications on the high tides Tue,
with some potential for minor flooding around the time of high
tide at some locations with additional Coastal Flood Advisories
being needed.
Tidal departures are expected to eventually diminish by Wed as
the flow becomes a bit stronger offshore, and swell from Teddy
subsides/moves N of the region.
Swells enhanced by Hurricane Teddy (well offshore), with
periods of ~15 seconds, and very large waves of 10-12 feet+
will make for very dangerous conditions at the Atlantic Beaches
through Tue. In addition, there is dune/beach erosion
potential, especially for more vulnerable locations with the
high tide cycle late tonight before conditions improve for
midweek. Beach Hazards Statements/High Rip Current Risk continue
early this week. A High Surf Advisory remains in effect for the
Atlantic coast as waves in the surf zone range from 8-10ft N to
10-12ft S.
&&
.EQUIPMENT...
As of 940 PM EDT Monday...
KAKQ radar remains offline due to an equipment issue. More info
will be passed along as it becomes available. See FTMAKQ for
more information.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...High Surf Advisory until 2 PM EDT Tuesday for MDZ025.
NC...High Surf Advisory until 5 PM EDT Tuesday for NCZ102.
Coastal Flood Advisory until 6 AM EDT Tuesday for NCZ102.
VA...High Surf Advisory until 5 PM EDT Tuesday for VAZ098.
Coastal Flood Advisory until 6 AM EDT Tuesday for VAZ095-097-
098.
High Surf Advisory until 2 PM EDT Tuesday for VAZ099-100.
Coastal Flood Advisory until 8 AM EDT Tuesday for VAZ075-077-
078.
MARINE...Small Craft Advisory until 6 PM EDT Tuesday for ANZ634.
Small Craft Advisory until 11 AM EDT Tuesday for ANZ630>633.
Small Craft Advisory until 6 AM EDT Tuesday for ANZ638.
Small Craft Advisory until 7 AM EDT Wednesday for ANZ650-652-
654-656-658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...ERI/MAM
SHORT TERM...MAM/RHR
LONG TERM...MAM
AVIATION...ERI/MAM
MARINE...AJZ/CP
HYDROLOGY...
TIDES/COASTAL FLOODING...
EQUIPMENT...
Area Forecast Discussion
National Weather Service La Crosse WI
1047 PM CDT Mon Sep 21 2020
.UPDATE...
Issued at 633 PM CDT Mon Sep 21 2020
Currently monitoring scattered showers and a few storms across
north central WI. These were along some 850mb moisture transport
and warm air advection. With better moisture transport waning,
expecting these showers and storms to diminish this evening. Will
then be monitoring a decent mid-level shortwave trough pushing
across the Dakota as of this update. This wave will be pushing
east into our area after midnight tonight with some mid-level
frontogenesis noted by the RAP model. This is expected to fuel
isolated showers and perhaps a rumble of thunder or two. So, have
added the mention of a slight chance of storms after midnight which
is a change from this afternoon`s thinking.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 143 PM CDT Mon Sep 21 2020
A bit of upper level energy will spin out of the Northern Plains
tonight, slipping across WI Tue morning. The shortwave will push a
sfc front across the region, taking on a west-east orientation. With
some weak 850 mb transport into the front, most meso models suggest
there will be enough saturation/lift for isold/scattered showers -
perhaps even a rumble of thunder with elevated instability
(evidenced in RAP bufkit soundings). For now, enough support to
include small rain chances tonight (will hold off on thunder for
now). Amount looks minimal, mostly coming out of a mid deck with
some drier air under cloud bases to work on (maybe just virga in
spots).
.LONG TERM...(Tuesday night through Monday)
Issued at 143 PM CDT Mon Sep 21 2020
A weak low pressure system and associated mid-level short-wave
trough looks to move into the region Wednesday night. Although low,
precipitation chances return with the system and last through
Thursday. There is some uncertainty with how far south these rain
showers develop, but currently expecting them to remain mainly north
of I-90 with better chances even further north of I-94. With a some
instability, isolated storms are possible, but the chances are
small.
Dry weather settles in to end the weekend as upper-level ridging
builds over the region. Afternoon temperatures in the 70s to low 80s
are expected. A more substantial and deeper extending trough is
anticipated to drop through the region over the weekend. Widespread
rain chances last from Saturday afternoon into Sunday. Will keep an
eye on storm chances as there is a decent amount of shear
available, but there is a limited amount of instability. Storm
chances would depend on where the precipitation develops in relation
to the surface front. Low-level shear looks better ahead of the
front along with better instability, whereas deep-layer shear is
better along and behind the front. After this system passes,
temperatures cool down into the 60s and low 70s to start off the new
week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1045 PM CDT Mon Sep 21 2020
VFR conditions through the TAF period. Pre-frontal showers
continue to linger just south of La Crosse and cloud trends show
some patchy mid clouds across southern MN and somewhat better
development south of the TAF sites. A subtle shortwave trough is
pushing across MN into northern WI, but is not expected to be
strong enough to push the surface front south. Forecast soundings
and some of the short range indications bubble up a few showers
and with elevated instability around 350 to 400 J/kg around 14K
ft. With this area becoming saturated, could see a few rumbles of
thunder. Due to the isolated nature of the showers and storms,
will include an hour or two of vsch at KLSE around 08Z, otherwise
sct-bkn mid clouds fl100-150. Southeast to southwest winds 6 to
12kts.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...DAS
SHORT TERM...Rieck
LONG TERM...Peters
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Bismarck ND
931 PM CDT Mon Sep 21 2020
.UPDATE...
Issued at 930 PM CDT Mon Sep 21 2020
Skies are clear across the region and winds are generally less
than 10 mph. Current forecast looks good.
UPDATE Issued at 610 PM CDT Mon Sep 21 2020
With surface high pressure dominating the weather regime, we see
no need to change the forecast tonight. Clear or mostly clear
skies and light southwest to west winds.
&&
.SHORT TERM...(This afternoon through Tuesday)
Issued at 220 PM CDT Mon Sep 21 2020
No significant forecast issues in the short term period.
Currently, upper level low continues to push east across southern
Canada, with quasi-zonal flow aloft over the Northern Plains.
Decent pressure gradient north and east of sfc high pressure
positioned over southwest North Dakota contributing to gusty
west/northwest winds across my north and east this afternoon.
Winds will taper off mid to late afternoon as the sfc high
continues to build east across the state.
Southerly return flow develops from west to east tonight as high
pressure drifts to the east and low pressure develops off to our
west. A dry boundary layer and a clear sky will result in good
radiational cooling with overnight lows in the 40s to low 50s.
Tuesday will potentially be one of the warmer days of the week as
WAA develops northward across western and central ND along to
east of a sfc trough. HRRR does indicate the return of smoke into
the region late tonight through the day tomorrow, so daytime highs
may be impacted. For now kept with a model blend as perhaps only
western and southern areas look to be impacted by the smoke and
will warrant a reduction in temperatures. Will let the mid shift
relook things.
.LONG TERM...(Tuesday night through Monday)
Issued at 220 PM CDT Mon Sep 21 2020
An embedded mid level wave moving across the region Tuesday night
through Wednesday morning will combine with decent 0-6km shear and
elevated instability to trigger off a few showers and isolated
thunderstorm, mainly north of I94 and likely around to north of
Highway 2 along a weak cold FROPA. Confidence remains low we will
see any severe weather, but wouldn`t be surprised a storm or two
could throw out a strong wind gust or some small hail given the
wave and shear advertised. In the wake of the front during the day
Wednesday, cooler temperatures in the 60s and 70s and a shift to
northerly winds are forecast ahead of a sfc ridge.
Winds transition to southerly for Thursday as high pressure
moves east and low pressure develops over eastern Montana.
Temperatures will rebound, perhaps robustly across the far west
where a few models depict a decent thermal ridge forming. Another
mid level wave will then push the sfc trough/cold front southeast
through the state Thu/Thu night though with a dry boundary layer
wouldn`t expect much moisture reaching the surface.
An upper level trough is still advertised to form across the
region for the beginning of the weekend, then a broad northwest
flow pattern Sunday/Monday. This pattern will result in cooler
temperatures and chances for showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 610 PM CDT Mon Sep 21 2020
VFR expected. High pressure centered near Aberdeen this evening
will drift southeast tonight. Clear skies are expected with
light southwest to west winds.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...NH
LONG TERM...NH
AVIATION...WAA
Area Forecast Discussion...CORRECTED
National Weather Service Boise ID
832 PM MDT Mon Sep 21 2020
.DISCUSSION...Today was warmer than forecast with less smoke and
better mixing than expected. But smoke was increasing from the
southwest late today and latest HRRR suggests it will continue
to increase overnight and Tuesday morning. That together with an
incoming weak upper trough will lower temps on Tuesday. Slight
chance of showers in northern mountains midday Tuesday otherwise
dry. Stronger trough and surface cold front will bring more
significant cooling Thursday and Friday. Current forecast is on
track.
&&
.AVIATION...VFR with areas of smoke. Mid to high clouds
increasing Tuesday morning. Isolated rain showers for eastern Oregon
Tue/11Z through Tue/16Z. Surface winds: variable 10 kt or less,
becoming west to northwest 5-15 kt Tuesday afternoon. Winds aloft
near 10k feet MSL: southwest 15 to 25 kt.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Wednesday night...Clouds will
increase overnight as a weak trough pushes into the interior NW.
East-central Oregon and the west-central Idaho mountains could
see a sprinkle/shower early Tuesday morning as the wave passes to
the north. Tuesday will be dry and a few degrees cooler. Southwest
flow returns on Wednesday bringing dry and breezy conditions along
with warmer temperatures. Winds will become gusty in the
afternoon across southeast Oregon and mountains of southwest
Idaho as flow aloft mixes to the surface. Clouds will increase
Wednesday night and showers are possible across northern zones
ahead of a trough pushing into the Pacific NW.
LONG TERM...Thursday through Monday...A cold frontal boundary
will make its way across the region Thursday bringing cooler than
normal temperatures and increased showers, mostly for our northern
areas. The associated trough axis will push through the area by
Saturday afternoon making way for an upper level ridge to build
offshore. Northwest flow aloft and drier conditions will prevail
for the remainder of the period.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
DISCUSSION...LC
AVIATION.....SH
PREV SHORT TERM...DG
PREV LONG TERM....JC
Area Forecast Discussion
National Weather Service Burlington VT
731 PM EDT Mon Sep 21 2020
.SYNOPSIS...
Expect dry conditions and the gradual warming trend to continue
right through midweek as high pressure remains over the region.
Low temperatures will not be as cold as the previous few night,
but frost will still be possible tonight, especially away from
Lake Champlain. Daytime highs are expected to reach seasonal
normals by Wednesday. It appears our next chance of rain will
come Thursday night as a cold front moves into the region.
Rainfall amounts however looks to be less than a quarter inch.
Above normal temperatures are expected for the weekend with
another chance of precipitation late in the day on Sunday.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 731 PM EDT Monday...Quiet and clear and cold overnight
conditions expected with some thin smoke aloft drifting through
the region. Latest HRRR smoke model shows thicker smoke aloft
currently over the Great Lakes will move into the North Country
tomorrow, so while no restrictions in surface visibility is
expected, added in haze to the forecast since the sky will be
cloudless, but not clear by any means in the afternoon.
Previous Discussion...Still looking at rather quiet weather
through Tuesday night with high pressure at the surface and
aloft over the region. The warming trend that began today will
continue right through Tuesday night. Lows tonight will not be
as cold as the last few night with lows generally in the 30s,
but some upper 20s over parts of the northern Adirondacks and
Northeast Kingdom of Vermont. Expecting frost at most locations,
except in and around Lake Champlain. Will not be issuing a
Frost Advisory for the areas that have not seen a killing frost
or freeze, but will carry the mention of frost in the forecast.
We are starting to pick up some high level smoke from the
western United States fires, but smoke is expected to remain
high enough to have no impact on air quality. Should see the
impacts of the smoke mainly at sunset and sunrise.
Warming trend continues on Tuesday with highs getting into the
60s across the entire area. One item of note will be the
pressure gradient strengthening across the area with Hurricane
Teddy moving north toward the Canadian Maritimes. This will
result in more wind than today with areas across Vermont
experiencing northwest winds in the 10 to 15 mph with gusts in
the 20 mph range. Slightly less wind is expected for northern
New York. No precipitation is expected on Tuesday and Tuesday
night for that matter. Tuesday night should be frost free with
lows generally in the 40s.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 257 PM EDT Monday...Relatively quiet period with mainly
increasing clouds on Wednesday as a weak shortwave passes
through NW flow off. Not expecting any measurable precipitation,
but with moisture between 5000-10000 feet, a few sprinkles may
be possible across the higher terrain. Otherwise, it should be a
mostly dry day with near seasonable temperatures in the mid to
upper 60s and overnight lows in the upper 40s to low 50s. While
clouds may obscure viewing, smoke from the western wildfires
will once again advect back into the region, but similar to last
week this smoke will remain high in the atmosphere with no
impacts expected locally.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 257 PM EDT Monday...Little changes made to the forecast
with best chances for a widespread, wetting rain to occur
towards the end of the weekend into early next week. Upper level
flow will turn out of the west behind the weak shortwave on
Wednesday, with another impulse moving through 500mb flow late
Thursday into Friday morning. Plume of moisture extending from
the Great Lakes into New England should provide enough for some
light rain showers across the area. The best chance for any
measurable rainfall will be for locations near the international
border where 0.10-0.25" is possible.
After this, subtropical high becomes well established across the
eastern US with dry weather expected Friday, Saturday and most of
Sunday. Sfc-850mb flow turns out of the southwest Saturday into
Sunday as digging upper level trough organizes across central US.
Saturday will feature above normal temperatures in the mid to upper
70s with fairly steady south winds, 10 to 15 mph. Low pressure will
move eastward Sunday night, and along with a pattern change for the
beginning of next week. Precipitation chances increase on Monday
with consistent signals for a fairly widespread precipitation event.
Large upper level trough remains across eastern US with continued
chances for rain through mid week.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...VFR conditions will prevail through the
period. Could see a brief period of IFR at KSLK or KMPV, but
confidence is too low and based on drier afternoon dewpoints and
slightly warmer overnight temperatures, think coverage will be
much less than last night. IF it does happen, it will be between
06-11Z. Otherwise, clear skies tonight will be replaced by a
layer of smoke aloft, but no clouds expected tomorrow. Light
winds overnight shift to the north tomorrow at 5-10kts.
Outlook...
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. Slight chance SHRA.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/Lahiff
SHORT TERM...LaRocca
LONG TERM...LaRocca
AVIATION...Lahiff
Area Forecast Discussion...Updated
National Weather Service Billings MT
845 PM MDT Mon Sep 21 2020
.UPDATE...
Quiet weather continues to dominate tonight, so no update needed.
Looking at the latest run of the HRRR Smoke, it still looks like
the smoke will continue to move back into the area with the
riding, but the surface impacts still look much less than the area
saw last week. Reimer
&&
.DISCUSSION...
Tonight through Wednesday night...
Upper ridging will prevail over the area into Tuesday, before a
weak late day cold front moves through during the late afternoon
and evening. Smoke from wildfires across the West will move back
into the area on Tuesday as well. The front may bring a few
isolated light showers to the higher terrain and eastern areas
during the evening. A rumble of thunder is possible over the
mountains as well. Ahead of the front, highs will reach the 80s
with afternoon RH into the teens, although winds are not expected
to be overall very strong. A few gusts into the 20s mph are
possible with the frontal passage in the evening.
Cooler conditions are expected in the wake of the front on
Wednesday with ridging building back over the region. Highs in
the upper 70s to around 80 degrees can be expected. STP
Thursday through Monday...
Thursday continues to look like a serious fire weather day. Fast WSW
flow aloft with a wave in the flow, will push a cold front SE into
the area during the afternoon. Winds will become gusty ahead of
the front and will remain gusty behind it, with gusts to at least
30 mph W of KBIL. Winds will be gusty in the E as well, but not as
strong as in the W. Temperatures will reach the mid to upper 80s
with the NBM showing a possible record temp of 89 in KSHR.
Humidities will be mainly in the teens across the area. Will add
a headline in the FWF discussion for Thursday.
It will be much cooler behind the front, and an atmospheric river
was progged to be over the area through Friday. Models showed
either zonal flow or a weak upper trough over the area on Friday.
Showers will move into the area behind the front Thu. night and
continue through Fri. night. Lows in the mountains will be in the
20s Fri. night which will support snow showers. Model clusters
showed increased pattern uncertainty for Saturday with solutions
ranging from a trough over the area to WNW flow. Saturday looked
like the windiest day of the period, with the EC ensembles showing
gusts to around 40 mph across the area. The NBM supported the
gusty winds. Scattered showers will continue over the area with
seasonable temps. Large high pressure ridge will dominate the West
for the rest of the period. There was uncertainty in the ridge
position in the clusters. EC ensembles showed possible gusty winds
during this period. At this point, temps and RH`s did not look
hazardous for fire weather. Arthur
&&
.AVIATION...
VFR conditions will prevail through the period. Winds will
increase again Tuesday afternoon ahead of a cold front. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 048/085 050/080 054/086 049/067 045/069 049/075 052/075
01/K 10/B 00/B 23/W 42/T 21/U 11/B
LVM 043/084 043/080 049/080 043/064 039/067 045/073 046/076
01/K 10/B 01/B 34/T 43/T 11/B 11/B
HDN 045/086 047/080 050/089 047/069 043/068 045/075 048/075
00/K 20/U 00/B 23/W 42/T 21/U 11/B
MLS 047/084 051/078 053/088 049/070 045/068 048/073 048/072
00/K 20/B 00/B 22/W 32/T 21/B 11/B
4BQ 047/087 051/080 052/090 048/071 044/068 046/073 047/072
00/K 20/U 00/B 12/W 43/T 22/W 11/B
BHK 048/085 049/077 049/085 048/068 043/066 045/070 045/068
00/K 10/B 00/B 11/B 42/T 21/B 21/N
SHR 046/089 046/081 049/088 044/070 039/068 042/074 045/073
01/K 20/U 00/B 14/T 54/T 22/W 22/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service State College PA
1037 PM EDT Mon Sep 21 2020
.SYNOPSIS...
High pressure over Pennsylvania will shift south of the state
during midweek. Increasing meridional upper level flow is
expected by next weekend, as a deepening trough forms over the
plains and an upper ridge builds off the east coast. At the
surface, expect a slow moving cold front to approach the state
from the west by late next weekend.
&&
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
Have only adjusted temps and dewpoints slightly to match up
with current obs/trends. As with the last few nights, many
places will flirt with freezing, and pretty much everyone
outside the urban of areas will have frost. Will hold the advy
in place with no changes.
Prev...
Temps and dewpoints nearly identical to 24hrs ago. Fcst mins
nearly identical to last night`s as well, and see no reasons
to change at this point.
Prev...
Tonight will be the last in a string of chilly nights with
frost concerns. Aside from Clearfield, Srn Center and Sullivan
Counties, whose growing seasons were ended this morning, Frost
Advisories will be hoisted in most of the same areas as last
night. Mins will be within a degree or two of Monday morning
mins.
&&
.SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Center of surface high will drifts south of PA Tuesday, allowing
a warmer push of air into the region on westerly flow. Abundant
sunshine, dry boundary layer will allow readings to reach back
to near seasonal average after 3 days of below normal highs.
One caveat...latest HRRR smoke model indicates smoke from
western fires will reach northwest PA Tuesday afternoon ahead
of shortwave crossing the Grt Lks, so maxes remain below
guidance over our northwest counties.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
The forecast for the extended/long term changes very little with
this evening update. The next real chance for rain is not until
late in the weekend. Previous disco tells the story very well.
Prev...
Mid level shortwave is progged to dive southeast across
the region Tuesday night. This moisture-starved feature is
likely to produce nothing more than a bit of mid/high level
cloudiness. However, a slight uptick on low level moisture,
combined with a light westerly breeze, should result in a milder
night than those recently with lows mostly in the 40s.
Shortwave and associated plume of upper level smoke should exit
the area by Wednesday. Large scale subsidence behind this
feature should translate to another mainly sunny day. Mixing
down ensemble mean 850mb temperatures of 12C yields expected
highs from the low 70s over the highest terrain of the
Alleghenies, to the low 80s in the Susq Valley.
Still looking very dry in the long term at least until next
weekend. Multiple waves moving along the US/Canadian border
will be starved of moisture. The only one of note would be
passing us Thursday night or Friday but that will most likely
just bring us some clouds. The GFS is wetter, making a few
hundreths here and there, versus the EC with this upper trough
passage. It does look like smoke aloft from
the western forest fires will return to the region toward the
middle of the week again giving us hazy skies. Due to this, I
lowered max temps by a few degrees Wednesday and Thursday. A
more robust trough looks to move into the region later next
weekend and early next week, which may bring a better chance for
showers.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR conds will continue tonight and tomorrow. Winds will be
light to calm overnight. Expect W to NW winds of 5 to 10 kts
with gusts of 15 to 20 kts on Tue.
Outlook...
Tue-Wed...VFR conditions.
Thu-Fri...AM valley fog poss, then generally VFR
Sat...Generally VFR, with rain possible Sat night
&&
.CLIMATE...
The record low temperature of 33 (1956) was tied at
Williamsport this (Monday) morning.
Cold temperatures were noted across the region the last 3
nights. Another cold night is in store for the region tonight.
With multiple reporting stations coming in below 32 degrees in
Clearfield, southern Centre and Sullivan counties, the growing
season has now ended for these zones.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 9 AM EDT Tuesday for PAZ024>028-
033>036-045-046-049>053-056>058-063>065.
&&
$$
SYNOPSIS...DeVoir
NEAR TERM...DeVoir/Dangelo
SHORT TERM...DeVoir
LONG TERM...Dangelo/Travis
AVIATION...DeVoir/Colbert
CLIMATE...
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
636 PM EDT Mon Sep 21 2020
.AVIATION...
Forecast remains on track for tonight and Tuesday. Winds will
quickly diminish to 5 knots or less after 00z. VFR conditions
through the taf period as large area of high pressure continues to
dominate the across the region. Winds will veer to more southwest by
Tuesday and increase to near 10 knots. An elevated front will
provide some mid/high clouds around 15kft Tuesday as the high keeps
the lower levels clear.
.DTW THRESHOLD PROBABILITIES...
* None.
&&
.PREV DISCUSSION...
Issued at 332 PM EDT Mon Sep 21 2020
DISCUSSION...
Dominant surface high pressure elongated through the Northeast
combined with a mid-level anticylone over the lower Ohio Valley will
maintain dry conditions for the remainder of today. 21.12 KDTX RAOB
measured a robust subsidence inversion near 750 mb which has now
lowered to around 800 mb. Light southeasterly flow has promoted
slight warm advection nudging high temperatures just above the 70F
mark for the first time since last Wednesday. Afternoon skies become
more opaque this evening from northwest to southeast with the next
round of Western wildfire smoke filtering in. Weak upper level flow
within a controlling ridge axis will transition tonight as the
feature pivots downstream toward the northwestern extent of
Hurricane Teddy, taking aim at Nova Scotia.
Winds will become nearly calm and re-orient southwesterly overnight
in the return flow regime. Outgoing longwave radiation will be
largely uninhibited by cloud-free skies allowing overnight lows to
settle a few degrees below climatological normals (mid-upper 40s) by
daybreak. Made slight adjustments to account for meager warming
influence of diffuse smoke aloft.
An approaching shortwave trough dampens slightly on Tuesday with
diminishing geostrophic winds as it moves zonally across the
northern Great Lakes. This feature will generate some mid-level
ascent/moisture advection capable of producing periodic altostratus
cloud. Given the dryness of the lower levels, precipitation is not
expected, even as PWATs trend upward to near 0.75 inches. The column
will also moderate with 850 mb temperatures rising 3-4C bringing
about a return to normal highs/lows. HRRR Vertically Integrated
Smoke suggests upstream trajectories will advect additional smoke
across all of Lower Michigan, thus bumped sky cover up a bit to
reflect this through the overnight hours.
Confluent flow aloft on Wednesday with the better jet branch
displaced to the north and east yields another dry day. It will be
the warmest day of the week as highs flirt with 80F near the Tri-
Cities and Metro areas. Dewpoints will be noticeably higher,
crossing the 60F threshold by midday as a narrow plume of moisture
spills southeast from Wisconsin. Expect some resultant marginal
MLCAPE, but given the moisture void above the boundary layer, only
impact will be some fair-weather diurnal cumulus and a few gusts
mixing down near 20 mph.
What remains of the upper low from Tropical Depression Beta will
breakdown over the Mississippi Valley on Thursday. This will clash
with some ridge running shortwaves dropping in from the northwest,
although mid-range guidance is not particularly well phased. Split-
flow over Southeast Michigan will limit the kinematics therefore
left low/dry PoPs through the end of the workweek.
Next opportunity for precipitation should arrive this weekend. The
ECMWF is a bit faster than the GFS with the arrival of a broad
longwave trough driving height falls and PVA into the Great Lakes
late Saturday into Sunday. The resident warm sector will be
displaced by a cold front extending up into central Canada with
plenty of FGEN and available moisture. Broad coverage of showers
will accompany the FROPA. Once it clears, temperatures will trend
cooler into early next week with additional rain chances on-deck
from a seasonably strong low pressure system Monday night.
MARINE...
High pressure along the Appalachians will reposition over the Ohio
Valley during the week continuing favorable boating conditions
through the period. A weak cold front will settle across northern
Lake Huron late Tuesday and remain near stationary through the week.
&
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....RBP
DISCUSSION...KK
MARINE.......DRC
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Green Bay WI
1039 PM CDT Mon Sep 21 2020
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 244 PM CDT Mon Sep 21 2020
Satellite imagery at 19Z showed a line of mid clouds stretching
from northwest Iowa, to southeast MN, and into northeast WI. There
have been scattered, weak returns on radar associated with these
clouds all day, but have not seen any signs of much, if anything,
reaching the ground across the GRB forecast area. There was a
lone lightning pulse in Vilas County around 1745Z. More recently,
some weaker thunderstorms have formed back to the west near
Minneapolis which coincides with a weaker band of CAPE and mid-
level lapse rates around 7.5 C/km. Given the current trends along
with some added support from a weak upper jet streak, expect this
band of clouds and occasional showers to continue this evening
and overnight, while also gradually shifting southward. Models
forecast CAPE up to 500 J/kg and mid- level lapse rates up to 8.0
C/km, so will maintain a slight chance of thunder as well.
Expect overall coverage and intensity to be low given the lack of
moisture.
Some patchy fog is possible across north- central WI early
Tuesday morning, meanwhile any lingering showers across east-
central WI will come to an end. The rest of the day looks quiet
and perhaps less hazy, as the HRRR smoke fields indicate the upper
level smoke pushes southeast tomorrow.
Temperatures will remain mild for early fall, with lows tonight in
the lower 50s, and highs for the first day of autumn in the lower
70s along the lakeshore, and in the mid to upper 70s everywhere
else.
.LONG TERM...Tuesday Night Through Monday
Issued at 244 PM CDT Mon Sep 21 2020
Forecast concerns generally revolve around precip chances on
Thursday and also over the weekend. The details keep evolving
during these two periods, as models struggle to maintain continuity.
Precip chances may be slowing down a tad on Thursday (and also
increasing) while speeding up slightly over the weekend. Have a
slight preference for the ecmwf.
Tuesday night through Wednesday night...The weak front will be
lifting north on Tuesday night into Wednesday as winds aloft back
from the west to the southwest. Though some clouds may linger along
the front, mainly over northern WI, dry and mild conditions look to
continue during these periods. Highs on Wednesday will remain in
the middle to upper 70s. The next shortwave will approach north-
central WI by late Wednesday night. Clouds will therefore be
increasing through the night, with most precip chances arriving
after midnight. Due to the slower timing, most thunder chances may
not arrive until very late in the night into Thursday morning.
Rest of the forecast...The shortwave energy will then proceed to
move across the region on Thursday, but also weaken in the process.
The highest chance of precip will therefore occur north and west of
the Fox Valley where a few thunderstorms will be possible. Most
models show precip amounts will remain on the lighter side, though
still some room for beefier amounts of precip if the stronger
solution works out. The clouds and precip will likely keep temps
cooler on Thursday. The chance of precip will come to an end by
Thursday evening. Then another surge of warm air will occur on
Friday into Saturday. Temps may approach 80 degrees at some of the
warmer locations. As a digging trough pushes a cold front into the
region, the chances of showers and storms will increase through the
day on Saturday. Models are showing a stronger system than 24 hours
ago, which could lead to the possibility of heavy precip and
thunderstorms. Then conditions turn cooler and showery for Sunday.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1034 PM CDT Mon Sep 21 2020
Light precipitation falling out of mid clouds (though with some
lightning) pushed across the north and was now sliding through the
southern part of the forecast area. Another shortwave will arrive
from the west overnight, and with steep mid-level lapse rates in
place it is possible additional light showers and even a few
additional thunderstorms could develop. Low-levels remain dry, so
bases should be relatively high.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KLJ
LONG TERM......MPC
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Grand Rapids MI
744 PM EDT Mon Sep 21 2020
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 306 PM EDT Mon Sep 21 2020
- Warm and Dry Through Saturday
- Wet and cooler Sunday through Wednesday
- Smoke will hang around into mid week
&&
.DISCUSSION...(This evening through next Monday)
Issued at 306 PM EDT Mon Sep 21 2020
-- Warm and Dry Through Saturday--
The official start of Fall is tomorrow at 931 am. The rest of
this week into the weekend is likely to be warmer than normal. The
average high temperature at Grand Rapids from the 22nd through
the 26th is 69 degrees. We are forecasting highs in the range of
75 to 78 during that time period. The normal low averages 48
degrees, which is what our forecast is for Tuesday morning, but
the rest of the week, lows are forecast closer to 56 degree. Both
the high and low temperatures are forecast between 5 and 10
degrees above normal.
We can thank the polar jet for being north of the Canadian border
for this. Also we have upper level ridging for the most part
through this period. We do actually have three shortwaves come
through this area during that time but the first two (tonight and
Wednesday) are on the northern stream and the 1000 to 850 mb flow
stays from the southwest even through the upper level winds do
briefly shift to the northwest behind each of these shortwaves.
That means we continue to get feed of warm dry air through the
week.
By Saturday we have the the first of the three Pacific shortwaves
that came from the area of eastern Russia coming into the Great
Lakes. That really increases the upper heights over us and results
in strong warm advection. I could see highs into the 80s if this
plays out that way. Still it will be to dry for rain, even then.
-- Wet and cooler Sunday through Wednesday--
By Sunday we start to see the impact of the second Pacific
shortwave coming toward us. Since there is a trailing wave digging
into the back of the Pacific trough near the dateline we get
strong rossby wave breaking over the Great Lakes as this is
happening. By Monday afternoon both the GFS and ECMWF and their
ensemble members. A deep upper trough with a closed upper low
develops near this area. This time we are deeply inside of the
cyclonic side of the polar jet. That will result in enough low to
mid level instability for lake effect showers, water spouts and
other related phenomena. It will also turn much colder. I would
expect area wide highs in the 50s at best by Tuesday.
The details of how this plays out at the surface for rain is still
being resolved by the models but the ensembles of the GFS (20)
and the ECMWF (50) all show precipitation in that time frame. At
this point it would seem later Sunday into Tuesday is when most of
the precipitation should occur. The ECMWF ensemble mean area wide
precipitation in on the order of an inch for that time period
with the greatest amounts, near 1.3 inches, being west of US-131
(lake effect enhancement).
-- Smoke will hang around into mid week--
The smoke is back and more than likely will remain around most of
this week since the overall mid level flow is from the west. Until
that changes (maybe by Saturday) we will continue to see that
smoke layer. From the RAP model smoke cross sections, it seems
most of it is between 5,000 ft and 20,000 ft. The greatest smoke
density is near 10,000 ft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 744 PM EDT Mon Sep 21 2020
VFR continuing with clouds above 12K ft and some smoke above 7K
feet. Light southeast sfc winds tonight becoming southwest around
10 kts by mid morning Tuesday.
&&
.MARINE...
Issued at 306 PM EDT Mon Sep 21 2020
Our wind/wave event north of Whitehall is playing out largely as
forecast. Ludington`s buoy has waves around 5 feet as of a few
minutes ago. Most of the marine buoys and near shore mesonet have
wind gusts in the 20 to 25 knot range. As the northern stream
system passes north of here the pressure gradient decreases. So,
the winds and waves will subside. We should be able to allow the
headlines to expire on time (8 pm).
The next event seems to be associated with the system coming into
the area on Saturday. Once in the area we may need marine
headlines into Tuesday or even Wednesday. If we get that rossby
wave breaking event to really happen we may need gales at some
point during that time.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ037-
043.
LM...Small Craft Advisory until 8 PM EDT this evening for LMZ848-849.
&&
$$
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Meade
MARINE...WDM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
623 PM CDT Mon Sep 21 2020
.SHORT TERM...
133 PM CDT
Through Tuesday night...
With a surface high pressure system position to our east, low
pressure system toward the north, and weak low to upper-level
tropospheric flow, persistence is the way to go for the forecast
through at least Wednesday. Lows tonight and highs tomorrow will be
a few degrees more than last night/today, and surface winds will
remain relatively light out of the south to southwest. Experimental
HRRR vertical integrated smoke indicates upper-level smoke will
continue to stream overhead through the foreseeable future, so
will also maintain wording for partial sky cover through at least
Wednesday morning.
Borchardt
&&
.LONG TERM...
253 PM CDT
Wednesday through Monday...
The generally tranquil and mild pattern will finally come to an
end this weekend with a frontal passage Saturday evening and
night. A cool and unsettled pattern could then unfold next work
week.
Wednesday will have a combination of increased high clouds and
likely lingering smoke aloft from western wildfires, but as 925 mb
temps rise into the upper teens Celsius, dry air mass should still
be conducive to warming into the upper 70s to around 80 for highs.
Thursday afternoon should also be primarily dry with similar to
maybe a hair cooler temperatures. There will be a fairly complex
pattern aloft with a short-wave trough rounding western and
central CONUS ridging. The ECMWF shears out the wave less and even
closes off 500 mb low for a time. If this general idea verifies,
some isolated to scattered showers may be possible in the northwest
CWA later in the afternoon into the evening. For now, maintained
dry NBM forecast.
The Thursday PM-night short-wave could then serve to effectively
block off moisture trajectories from tropical remnants to get
involved with Saturday evening and night`s frontal passage. At
this vantage point, Friday through Saturday afternoon appears dry
and mild/warm with highs around 80F on Friday and low to possibly
mid 80s on Saturday in breezy southwest flow immediately ahead of
the front. As mentioned, the moisture return on Saturday will be
lacking, so we might eek out a ribbon of dew points a couple
degrees either side of 60F. In addition, while there is time for
change in this, the current timing of large scale forcing from
stout digging trough and surface cold front is diurnally
unfavorable, happening primarily after sunset Saturday evening.
There will be enough forcing for at least scattered showers with
the front, but lacking instability and unfavorable timing should
limit thunder coverage to isolated/slight chance.
There`s pretty decent agreement for this far out that Sunday will
be between waves behind the cold front, so should be mostly dry,
and therefore collaborated PoPs downward to mainly slight chance.
Temperatures will step down to the lower to mid 70s, so still
could turn out a decent day. Medium-long range operational and
ensemble guidance is in good agreement in an impressive long-wave
trough setting up shop over the eastern CONUS (including Midwest)
next work week. Details of how we get there are a bit muddled to
start the work week. Impressive short-wave that will carve out
this trough could spur deep cyclogenesis over the Great Lakes
region on Monday and exact position of mass fields would determine
if we have a breezy/windy, wet and cool Monday, or just breezy and
lower rain/shower coverage if main forcing for precip passes just
north and east. For now, the lower-end NBM PoPs appear reasonable.
At least a few days of below to well below normal temperatures
appear likely behind Monday`s (day 7) secondary cold front passage.
Castro
&&
.AVIATION...
For the 00Z TAFs...
There are no major aviation impacts for the next 24 to 30 hours.
Light south-southeast will trend toward southwest on Tuesday.
Passing mid-upper level cirrus, coupled with occasionally smokey
skies at ~10,000 feet will prevail through the TAF period.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
914 PM EDT Mon Sep 21 2020
.SYNOPSIS...
High pressure will gradually build over and then south of the
area through the week while Teddy departs through the Canadian
Maritimes. A cold front will approach this weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
Another chilly night with lows in the mid 30s where Frost
Advisories are in effect. Could still see a few spots drop below
freezing like we had this morning, but not expecting a
widespread freeze although it sill should turn out cooler than
this morning.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
While notable weakening in the surface ridge is expected, the region
will be coming off another chilly night. Areas of frost are
likely to start off Tuesday morning, mainly west of the Blue
Ridge and into colder sections of northern Maryland. Gradually
all locations will warm up as nocturnal radiational inversions
are mixed out by mid-morning. On the synoptic scale, a powerful
upper trough is forecast to be located well off the Atlantic
coast as Hurricane Teddy is steered toward the Canadian
Maritimes. Farther upstream along the Eastern Seaboard, a
transient shortwave ridge moves through which bumps temperatures
up a bit. With 1000-500 mb thicknesses rising by around 3 to 5
dm from the previous day, expect afternoon highs to reach the
low 70s accompanied by low dew points.
Heading into Tuesday evening and night, additional western U.S.
wildfire smoke will again enter the picture. Recent HRRR smoke loops
and cross-sections show mid to upper-level smoke filling the
skies. While this will not influence surface visibilities, it
should create a hazy appearance in the sky. These conditions
are likely to be in place at least through Wednesday which may
keep temperatures down during the afternoon. Most ensembles
bring highs to around 80 which may be difficult to muster
depending on how much smoke limits incoming solar radiation.
Unlike previous nights, Wednesday night will be much milder
given an increase in cloud cover and the surface high shifting
its position into the Tennessee Valley.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Overall good agreement amongst guidance in regards to the extended
period. High pressure will remain offshore Thursday into Friday,
resulting in continued dry conditions. Meanwhile, the leftover
moisture from Beta will be picked up by the southern jet stream
as it slowly moves eastward. Strong high pressure over the Gulf
of Maine may suppress most of the moisture south of our CWA,
keeping the bulk over southern VA/NC. However, cannot rule out
some shower activity both Saturday and Sunday as a decent amount
of uncertainty remains.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
VFR expected thru Wed night.
HRRRX cross sections and upstream satellite suggest smoke from
western wildfires is again likely to move over the area by
around nightfall Tuesday and persist through Wednesday as low as
8-12 kft AGL.
VFR conditions are expected Thursday and Friday with high pressure
offshore, coupled with a light southerly flow. Patchy fog may
briefly reduce vsbys during the early morning hours both days.
&&
.MARINE...
Winds have diminished and model trends indicate winds continue
to weaken tonight as high splits and settles over the area. Have
canceled advisories. As the high center weakens and shifts
south, winds will become westerly Tuesday into Wednesday.
High pressure will build offshore Thursday and Friday, and a
southerly flow is expected. However, the gradient should be light
enough for winds to remain below SCA criteria most of the time.
&&
.TIDES/COASTAL FLOODING...
Onshore flow will maintain elevated water levels through
tonight. Minor flooding is likely for sensitive areas with the
high tide cycle through high tide Tue morning.
The flow will turn more westerly for Tuesday and may cause
anomalies to decrease. However, there will be water piled up
near the mouth of the Bay, and some of that water may still make
it into our area since the flow will be relatively light.
Therefore, minor flooding is still possible. Confidence is low
at this time.
&&
.EQUIPMENT...
The KLWX (Sterling, VA) WSR-88D is out of service until further
notice. The outage is due to a failure within the Radar Data
Acquisition Functional Area that occurred early in the morning on
September 20, 2020.
KLWX will be out of service for at least several days, as
subject-matter experts from the National Weather Service Radar
Operations Center will diagnose the failure, and then perform
maintenance action in order to return-to-service.
Users of KLWX can utilize adjacent weather radars located in Dover
DE (KDOX), Mt. holly NJ (KDIX), Pittsburgh PA (KPBZ), Charleston
WV (KRLX), Blacksburg VA (KFCX), and Wakefield VA (KAKQ).
Further updates to keep users informed about the situation will be
issued as information becomes available. Thank you for your
understanding during this extended outage.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory until 2 AM EDT Tuesday for DCZ001.
MD...Frost Advisory until 9 AM EDT Tuesday for MDZ003>006-501>503-
505-507.
Coastal Flood Advisory until midnight EDT tonight for MDZ014.
Coastal Flood Advisory until 8 AM EDT Tuesday for MDZ017.
VA...Frost Advisory until 9 AM EDT Tuesday for VAZ025>031-040-051-
501>505.
WV...Frost Advisory until 9 AM EDT Tuesday for WVZ050>053-055-
501>506.
MARINE...None.
&&
$$
SYNOPSIS...LFR/DHOF
NEAR TERM...LFR
SHORT TERM...BRO
LONG TERM...MSS
AVIATION...MSS/LFR
MARINE...MSS/LFR
TIDES/COASTAL FLOODING...
EQUIPMENT...LWX
Area Forecast Discussion
National Weather Service Marquette MI
842 PM EDT Mon Sep 21 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 424 PM EDT MON SEP 21 2020
Water vapor imagery and RAP analysis show a mid-level low along the
Manitoba/Ontario border to the ne of Lake Winnipeg. 850mb theta-e
ridge that was advected ne ahead of a shortwave that pivoted around
the low currently runs from se SD ne across western Lake Superior.
Theta-e advection to the e of the axis along with steep mid-level
lapse rates of 7-8C/KM is supporting sct high based radar returns in
a sw-ne band from around the Twin Cities to eastern Lake Superior.
Given the dry air noted on the 12z GRB/MPX soundings, probably not
much more than sprinkles reaching the ground from much of these
echoes over the fcst area. Some lightning is beginning to show up to
the sw in WI where MUCAPE increases to around 500j/kg. Otherwise,
it`s been a partly to mostly sunny, breezy day with wind gusts
generally in the 20-30mph range. Temps have pushed into the mid 60s
to mid 70s.
Into the evening hrs, 850mb theta-e axis will shift e just ahead of
850mb trof which will clear the fcst area during the night. Theta-e
advection and steep mid-level lapse rates will continue to result in
a relatively narrow band of sct high based -shra developing thru the
evening hrs. With an axis of several hundred j/kg of MUCAPE in the 1-
3km layer ahead of the 850mb trof, expect some rumbles of thunder as
well. Convection will shift w to e during the night, exiting the
eastern fcst area overnight. Breezy conditions will continue into
early evening. Otherwise, expect a mild night with lows in the 50s.
Tue will be a dry day with sfc high pres ridge moving over the area.
Under 850mb temps of 12-14C, it will be a warm late Sept day under
mostly sunny skies. Expect max temps in the 70s. A few spots over
the interior s central may reach 80F. With the sfc high pres ridge
arriving, lake breezes will develop across the board, providing some
cooling lakeside in the aftn.
.LONG TERM...(Tuesday night through Monday)
Issued at 400 PM EDT MON SEP 21 2020
The long-term period begins with continued ridging Tuesday night and
Wednesday. NAEFS 850 mb temps are progged to remain around the 90th
percentile for this time of year, and with mostly sunny skies and
deep mixing, should have no problem translating that into highs in
the mid to upper 70s. Weak background flow will allow afternoon lake
breezes to develop, keeping the immediate lakeshores in the upper
60s to low 70s instead.
By late Wednesday afternoon, a short wave riding along the northern
periphery of the ridge will begin to dip down across the Upper Great
Lakes bringing a chance of showers with it. Expect a weak warm front
to develop across the U.P. with showers and possibly storms riding
southeastward along it. Showers and perhaps some elevated
thunderstorms (mostly weak) look likely Wednesday night, especially
early on. Given the run-to-run consistency in the models, increased
POPs over NBM initialization to get some likely POPs for the west
half. Also included chance thunder out west given anywhere from 500
to a little more than 1000 J/kg MLCAPE in the models. Given storms
will probably be elevated, used 1-6 km bulk shear vectors; those are
still around 30 kts which could support some modest storm
organization. However vectors are parallel to the boundary, which
would probably mean training multicells, if that.
The question for Thursday will be how amplified the system is and if
the UP can end up getting into the clear warm sector before the cold
front arrives on Thursday. The 12z NAM shows this happening with
MLCAPE and deep-layer/low-level shear at least marginally supportive
of strong to severe thunderstorms... but other models do not show
this happening. Given the cold flow off Lake Superior and the NAM`s
bias towards deeper surface cyclones in the medium range that don`t
verify, think a GFS-like scenario is the more likely outcome. That
ends up being just cloudy skies for the north half and some showers
and maybe isolated weak storms lingering along the southern edge of
the CWA.
Short wave ridging building in behind this wave leads to another
warm and mostly sunny day Friday. A 30-40+ kt LLj moving in ahead of
the next wave will lead to breezy south winds on Friday, especially
if cloud cover holds off (which right now it looks like it will).
Will likely need to increase winds during for the Friday afternoon
period in future forecasts. By Saturday, models are in good
agreement that a more potent mid-level wave will be digging into the
Northern Plains and a cold front pushing east. This front will
likely be the focus for numerous showers on Saturday, as well as
possibly some thunderstorms given model progs of 1000 J/kg or more
MUCAPE. In addition to any pre-frontal convection, models
(especially the GFS) show a classic anafront precip pattern with the
upper-level jet oriented such that the right entrance region falls
behind the front. Therefore, a soaking rain is likely to continue
behind the front for much of Saturday night as well.
Looking even farther out, the GFS continues to advertise a very
strong system early next week followed by a return to more
seasonably chilly air. Today`s 12z EC shows a similar solution as
well, albeit not as strong. Still plenty of time to see how that
evolves in the models over the next couple of days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 832 PM EDT MON SEP 21 2020
Isold -shra into early evening at KSAW, but otherwise expect VFR
conditions with clearing skies from the west overnight. Low-
level jet will be shifting e of the area later tonight, but there
will be a period this evening when decoupling winds may result in
LLWS at KSAW before the low-level jet departs. Under building sfc
high pressure, expect light winds with developing lake breezes on
Tuesday.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 424 PM EDT MON SEP 21 2020
Pres gradient will finally weaken tonight as a weakening sfc trof
crosses Lake Superior, followed by a high pres ridge which will
arrive over the lake on Tue. As a result, ongoing 20-30kt winds over
a good portion of the e half of Lake Superior will diminish to 15-
25kt tonight. Could be a few gale force gusts this evening at high
obs platforms and toward the nearshore waters e of Marquette. Over
the w half, winds will mostly be under 20kt tonight, though some
gusts to 25kt are expected. Winds will fall off to under 15kt Tue
thru Wed with passing sfc high pres ridge. A cold front will cross
Lake Superior Wed evening. With weakening low pres along the front
over the Upper Mississippi Valley and high pres shifting se across
northern Ontario, ne winds may ramp up to 20-30kt for a time across
the w half of Lake Superior late Wed night/Thu morning. Otherwise,
winds will be mostly under 20kt Thu into Fri morning. Southerly
winds will then increase Fri/Fri night, strongest over the e half
where winds should reach 20-30kt.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...RJC
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service New York NY
739 PM EDT Mon Sep 21 2020
.SYNOPSIS...
High pressure will remain in control through Tuesday. High
pressure remains over centered over the Mid-Atlantic into
Thursday before a weak frontal system approaches from the Great
Lakes into Friday. High pressure returns to start the weekend
period as a stronger cold front approaches the region for early
next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Forecast is on track this evening. Have trended temperatures
and dewpoints down a bit to reflect current trends. Otherwise,
tranquil conditions are forecast tonight with high pressure
remaining over the northeast. Winds will diminish and combine
with clear skies to promote excellent radiational cooling
conditions. Temperatures are expected to fall into the middle
30s across the interior and Long Island Pine Barrens, with lower
to middle 40s most elsewhere. Areas of frost are likely across
the interior and have issued a frost advisory from 2 am to 9 am
Tuesday.
There is a high risk of rip currents at the Atlantic Ocean beaches
through this evening due to high seas and long period swell.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
The surface high will weaken on Tuesday as it shifts to the south
and west of the region. Teddy will lift to the north and continue to
become extratropical as it merges with a strong upper low off the
New England coast. The repositioning of the surface high and Teddy
passing offshore will create a stronger pressure gradient and result
in a bit breezier conditions.
Otherwise, highs will moderate back closer to normal in the lower
70s.
Mostly clear conditions are forecast Tuesday night, but there may be
some increase in smoke aloft from the wildfires across the west as
it moves around the periphery of the upper level ridge. This is
supported by the vertically integrated smoke field of the HRRR. The
hazy sky could persist into Wednesday morning. Lows will likely be
much milder than recent nights, falling into middle and upper 40s
inland and 50s elsewhere.
There is a high risk of rip currents at the Atlantic Ocean beaches
on Tuesday due to high seas and long period swell.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Surface high pressure remains anchored over the mid-south as Teddy
heads well to the northeast. As a result the pressure gradient
relaxes by Wednesday afternoon. The surface high slides east on
Thursday as surface winds locally will become more southerly by
Thursday afternoon. Temperatures and moisture will be on the
increase, as warm advection commences under the southerly flow.
Temperatures begin to feel more climatologically normal for this
time of year. HRRR is also showing vertically integrated smoke
passing well overhead again on Wednesday afternoon. This will
remain at very high levels and appear like thin cirrus overhead.
Back to the west an upper trough takes shape over the OH Valley and
brings through a weak cold front by Friday. Guidance continues to
keep the area basically dry, with the bulk of any precipitation
staying south of the area where upper forcing is a bit better. The
front clears the coast by Friday afternoon and the upper trough axis
swings trough by early Saturday.
Upper ridging then builds in for the weekend with high pressure to
the northeast and mainly dry and seasonable conditions, with highs
in the mid to upper 70s. A deep upper trough and cold front
approach by Monday morning bringing a rain chance by Monday
afternoon into Tuesday. Models are differing on the evolution of
this system the ECMWF increasing cloud cover and shower chances by
Sunday evening with the weak development of surface low south of the
area ahead of the main system. The GFS, however is keeping us
mainly dry until Monday afternoon with the passage of the front.
Given the Days 6-7 timeframe and inherent uncertainty, for now have
increased PoPs on both Sunday afternoon and Monday. Temperatures
look to remain seasonable, or just above.
There is a high risk of rip currents at the Atlantic Ocean beaches
on Wednesday due to lingering high seas and long period swell.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
High pressure will be stationary and north of the region,
remaining in control through the TAF period.
VFR conditions will prevail through the TAF period and winds will
remain in a general N-NE flow but back to more NW-N on Tuesday.
Winds tonight and overnight near 5 kts. Sustained winds will be near
10-12 kt by late morning. Gusts mainly to 20-24 kt are expected by
the afternoon and subside after 23Z Tuesday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Magnitude and duration of gusts may extend a little longer into
Tuesday evening especially eastern terminals.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
.Tuesday Late afternoon...VFR. N-NW winds with gusts to 24 kt.
.Wednesday through Saturday...VFR expected.
Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90
&&
.MARINE...
No changes were made to the SCA that goes through Wednesday
afternoon. Winds on the ocean will gust 20-25 kt tonight and
then 25-30 kt on Tuesday into Tuesday night. There may also be
occasional gusts around 25 kt on the eastern LI Bays and eastern
LI Sound. If the gusts look more frequent, then an SCA will be
needed here on Tuesday. Elevated seas will remain on the ocean
due to long period swells from Hurricane Teddy which will pass
well east of New England on Tuesday. See the National Hurricane
Center for official forecasts on Teddy.
Atlantic ocean seas will remain elevated on Wednesday, with 4-6 ft
wave heights across the waters diminishing by Wednesday
evening. Wind gusts may approach 20 kts as well on Wednesday
afternoon.
Winds and seas are expected to remain below small craft levels from
Thursday through SUnday evening. Small craft conditions may return
by Monday. Waves of 4-6ft and gusts nearing 20kts may be possible
across the Atlantic Ocean waters, in association with an approaching
cold front.
&&
.FIRE WEATHER...
A warmer and drier day is forecast on Tuesday with min RH
values less than 30%, particularly across CT. Winds may also end
up a bit stronger. A Special Weather Statement was issued this
evening for southern CT through Tuesday evening as a result.
&&
.HYDROLOGY...
No hydrological concerns are anticipated through next Monday.
&&
.TIDES/COASTAL FLOODING...
Astronomical high tides will continue to run high and will
combine with long period swells and high seas from distant
Hurricane Teddy in the Atlantic. The higher of the tides
continues to be during the day time. Tide levels are forecast to
remain below benchmarks tonight and Tuesday night. Widespread
minor coastal flooding is likely Tuesday afternoon along the
south shore back bays of Nassau and Queens as well as Southern
Westchester and Southern Fairfield on Tuesday. Isolated minor is
forecast for the rest of the Long Island coast and lower NY
Harbor with the Tuesday afternoon high tide.
Another episode of minor coastal flooding is possible on
Wednesday afternoon as long period swells will only slowly
subside. However, have held off on any products for Wednesday
until confidence in total water levels increase.
The high surf advisory has been extended through 6 am
Wednesday. Wave heights of 7 to 12 ft are forecast, highest
into Tuesday. Widespread dune erosion and scattered overwashes
expected for the ocean beachfront today through Tuesday evening.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory from 2 PM to 6 PM EDT Tuesday for
CTZ009.
Frost Advisory from 2 AM to 9 AM EDT Tuesday for CTZ005>008.
NY...Coastal Flood Advisory from 2 PM to 6 PM EDT Tuesday for
NYZ071.
Frost Advisory from 2 AM to 9 AM EDT Tuesday for NYZ067-068.
High Rip Current Risk through Tuesday evening for NYZ075-080-
081-178-179.
High Surf Advisory until 6 AM EDT Wednesday for NYZ080-081-178-
179.
Coastal Flood Advisory from 11 AM to 4 PM EDT Tuesday for
NYZ178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ350-353-
355.
&&
$$
SYNOPSIS...DBR/DS
NEAR TERM...DBR/DS
SHORT TERM...DS
LONG TERM...DBR
AVIATION...IRD
MARINE...DBR/DS
FIRE WEATHER...DBR/DS
HYDROLOGY...DBR/DS
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Pittsburgh PA
758 PM EDT Mon Sep 21 2020
.SYNOPSIS...
Dry weather with gradually warming temperature can be expected this
week under high pressure.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Another good radiation night under dry high pressure will support
a rapid temperature drop. With dewpoints in the lower 30s, a little
more moisture is available for frost formation, so an advisory was
issued for the extreme northern, and ridge zones of the Upr OH Valley
Region.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Persistently pleasant weather will prevail through midweek with
surface high pressure. A gradually warming trend is likely as weak
warm advection resumes on the west side of high pressure in the low-
levels, with each subsequent day likely being a slightly warmer than
the preceding day. Overnight lows both Tuesday night and Wednesday
night will be warm enough to preclude any frost development.
HRRR vertically integrated smoke indicates upper-level smoke will
return by Tuesday afternoon.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
A shortwave trough will lose amplitude as it moves across the
Central CONUS to the Upper OH Valley region by Thursday. Cloud cover
will increase with its approach and passage, though a lack of deep
layer moisture should preclude rain chances.
Ridging building across the Eastern CONUS, ahead of an approaching
Central CONUS trough, should result in clearing skies and dry weather
through the first half of the weekend. The trough is progged to
approach the Upper Ohio Valley region Saturday night and Sunday,
resulting in scattered showers. Temperatures are expected to average
5 to 10 degrees above seasonable levels through the period.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
High pres wl cont to maintain VFR and lgt wind, marred only by some
brief and shallow peri-dawn fog at terminals next to the rivers.
.Outlook...
VFR is likely to prevail into the weekend despite the remnants of TS
Beta advancing north. Low and mid-level dry air will keep cigs above
4kft.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Frost Advisory from 2 AM to 9 AM EDT Tuesday for MDZ001.
OH...None.
PA...Frost Advisory from 2 AM to 9 AM EDT Tuesday for PAZ009-015-016-023-
074-076.
WV...Frost Advisory from 2 AM to 9 AM EDT Tuesday for WVZ512>514.
&&
$$
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
458 PM MDT Mon Sep 21 2020
.DISCUSSION...(This Evening Through Monday)
Issued at 150 PM MDT Mon Sep 21 2020
Main fcst problem this afternoon revolves around how fast
smoke/haze will push back into cwa later this
evening/overnight...and fire weather concerns for Tuesday and
again on Thursday.
Departing low across srn Canada will result in quick moving zonal
flow at 500hpa level across upper midwest through mid-week.
Embedded minor waves would provide a spark of interest...but very
dry lower layers look to prevent any measurable pcpn pops from
being inserted into fcst. WAA moves in at 850hpa level with flow
moving more sw. HRRR smoke fcst also shows increasing smoke/haze
intruding into cwa beginning 00z tonight and increasing through
the next 24-36 hours...so have increased coverage in the wx grids
to account for this.
With the warmer temps Tuesday...fire weather concerns raise
eyebrows...especially across wrn cwa. However...lack of sfc winds
prevents any headlines at this time.
Then for Thursday...seems like a slightly better chance for fire
weather headlines as winds in the sw cwa increase with the waa
pattern. This far out...will monitor.
Best chances for pcpn appear to be on the weekend as stronger
500hpa/700hpa trofs push through the region. Again...scant
moisture to work with...but a bit better dynamics around. This
system results in highly amplified CONUS pattern with west coast
ridge/east coast trof for next week.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening)
Issued At 451 PM MDT Mon Sep 21 2020
Smoke will begin moving back into the region tonight, but
expecting conditions to remain VFR through Tuesday.
&&
.FIRE WEATHER...
Issued at 150 PM MDT Mon Sep 21 2020
Warm and dry conditions will continue through the forecast
period...with Tuesday and Thursday being the most critical days
for fire weather concerns. Hot temps and low Rh values will be
present on both days...but winds will be strongest on Thursday.
The best pcpn chances are Saturday when a stronger cold front
moves through the region.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Hintz
AVIATION...Pojorlie
FIRE WEATHER...Hintz