Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/03/21
Area Forecast Discussion
National Weather Service Bismarck ND
943 PM CDT Sat Oct 2 2021
.UPDATE...
Issued at 937 PM CDT Sat Oct 2 2021
The forecast for tonight remains on track.
Smoke continues to move south/southeast across central and
portions of western North Dakota late this evening. Visibility
overall has fluctuated from 2 to 5 miles due to the smoke. HRRR
smoke model has handled the denser part of the smoke well, but
did fail to capture the true aerial extent. This was easy to fix
using sfc obs and DOT web cams. Highlighted the smoke on social
media (where the smoke is coming from and how long it will last).
UPDATE Issued at 627 PM CDT Sat Oct 2 2021
Once again tweaked areas of smoke based on sat imagery, sfc
obs, and DOT web cams. Basically sped up the timing of the south
and eastward progression, and expanded slightly to the west. Main
area of smoke will push south/southeast across most if not all of
central areas of North Dakota now through tonight. Question then
is how long smoke lingers Sunday morning. For this product
issuance, ended smoke at 12Z and will reassess later tonight
whether to expand in time or not.
All other forecast elements on track.
UPDATE Issued at 510 PM CDT Sat Oct 2 2021
Just a quick update to fine tune/tweak areas of smoke based on
latest sfc observations and high resolution numerical guidance.
Overall these changes were minor from what was inherited.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 137 PM CDT Sat Oct 2 2021
Northwesterly surface winds have carried in wildfire smoke to our
northern counties from Saskatchewan. The smoke is very apparent
at the surface from satellite, airport observations, and human
reports. The thickest areas of smoke have dropped visibilities
below a mile at Estevan, SK, and may cause breathing issues for
those with respiratory concerns. This smoke should continue
drifting towards the southeast through the afternoon, while likely
becoming less dense.
Otherwise, with surface high pressure and upper level ridging
influencing the area, tonight should remain mostly clear with
temperatures falling into the upper 30s to lower 40s. Mostly clear
conditions will continue through the day Sunday, with temperatures
warming up into the lower 70s east to upper 70s/lower 80s across
the central and west.
.LONG TERM...(Sunday night through Saturday)
Issued at 137 PM CDT Sat Oct 2 2021
Our area will remain under upper level ridging for much of the
upcoming week, maintaining dry and mostly clear conditions along
with warm temperatures. By Tuesday, many locations across the
central and west will see high temperatures in the mid to upper
80s, with a couple of 90 degree readings not completely ruled out
given the pattern of temperatures generally over-performing. With
the warm and dry conditions, afternoon minimum humidity will be
very low (teens to low 20s) across the west and into the central
each day through mid week. Winds look like they might behave for
the most part, but increasing southerly winds Tuesday into
Wednesday ahead of an upper trough digging into the western CONUS
may lead to some near critical fire weather concerns across parts
of the forecast area.
A pattern change is still expected heading into the weekend as the
aforementioned trough makes its way into the northern Plains,
bringing a return to seasonable temperatures and chances for
showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 627 PM CDT Sat Oct 2 2021
A large area of smoke originating from far south central Canadian
wildfires will push south/southeast across central North Dakota
now through tonight. Impacted terminals include KMOT now through
early Sun morning, KBIS early this evening through around 12Z
Sun, and KJMS later this evening through parts of Sun morning.
Occasionally reduced visibility is possible, but should remain
mainly VFR as the smoke is expected to become less dense with
time. Otherwise, VFR conditions are expected through the period
with mainly light winds.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...Gale
LONG TERM...Gale
AVIATION...NH
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1156 PM EDT Sat Oct 2 2021
.AVIATION...
IFR to possible LIFR ceilings will develop overnight into Sunday
morning as low level moisture behind warm front continues to funnel
into the area. Showers will also become more numerous overnight with
periodic showers on through Sunday into Sunday night as low pressure
shifts slowly east into the region. A period of lower MVFR cigs may
develop Sunday afternoon, but showers will be on the increase late
in the day as the aforementioned low arrives and more or less stall
over/near the forecast area.
For DTW...Expect MVFR to IFR cigs as the forecast begins with
LIFR not out of the question late tonight/early Sunday morning.
Showers will increase into the overnight with continue on/off on
through Sunday.
.DTW THRESHOLD PROBABILITIES...
* High for ceilings 5000 feet or less throughout the forecast.
* Very low for a thunderstorm at the terminal overnight into Sunday.
&&
.PREV DISCUSSION...
Issued at 332 PM EDT Sat Oct 2 2021
DISCUSSION...
580dam H5 ridge will completely break down this afternoon leading to
increasing cyclonic flow and a wash of deep column thetae. Early
stages of broad wavelength troughing yields very little organized
low level jet axis, in fact, SPC RAP based mesoanalysis shows only
weak moisture transport vector in place over the region this
afternoon. Model data supports a coherent, upright warm front
between 925-650mb working across the cwa between 18-21Z this
afternoon. Elevated shower activity will now be
possible anytime after 21Z. Moist adiabatic lapse rates bring weak
static stability above 7.0 kft agl with a very dry boundary layer.
Inverted V sounding and evaporative potential yields some chance for
gusty winds with convective shower activity. The better chance for
an isolated rumble of thunder may be after the intiial moisture
surge and reside along a 900mb frontal surface after 00Z. Low
confidence exists in any lightning activity. Most focused of
activity may occur south of the M 59 corridor this evening. Weak
static stability will then support occasional shower activity
throughout the night.
Plan view of moisture progs show the richest thetae plume will work
eastward tonight with the western flank still in place to begin the
day Sunday. The main absolute vorticity center is forecasted to lift
out of the central Plains to near Chicago by 18Z Sunday supporting
lower tropospheric low pressure develoment over southwest Michigan.
Forcing mechanism to key off of Sunday will be the development of a
stretching deformation axis that should set up over the northern 1/2
of the cwa. Favorable convergence axis and upper level diffluent
flow will become positioned with large scale geopotential height
falls. Hires models show activity occurring north of I 69 during the
morning then diabatic heating leading to increased convective
development during the afternoon across Southwest Lower Michigan in
closer proximity to surface low. Latest signal then carries
afternoon shower and potential thunderstorms to the northeast
coalescing under the stretching deformation axis well into Sunday
evening and night. Very little steering flow brings concern for slow
moving convection and heavy rainfall. PWAT values are forecasted to
reach 1.60 inches supportive of heavy rainfall. The potential will
exist for thunderstorms but marginal instability at 1000 J/kg and
weak deep layer shear limits the risk. Current trends in QPF suggest
that total QPF amounts could exceed 1.00 to 1.50 inch along a west
to east corridor near I 69.
Barotropic low pressure will then be in place over Southeast
Michigan Monday through Tuesday. The pattern will be dicated by
background easterly flow trajectories that will bring seasonally
moist and warm wrap around conditions to the state. Not expecting a
washout Monday but persistent of surface low near Detroit supports
the likely PoPs.
A Rex Block is then forecasted for the middle of next week. Main
question for the forecast is timing or how progressive the closed
low over the southern United States will be. Latest indications are
the closed low will lift northward and plague the region possibly
through the end of the week and next weekend. Seasonally mild to
warm temperatures are expected. Low chance PoPs are in place.
MARINE...
A stationary front extends east across northern Lake Huron from low
pressure over the northwestern Great Lakes. This weak low tracks
slowly southeast tonight into Sunday, passing directly over the
central Great Lakes by Sunday afternoon. The gradient will remain
weak and hold wind speeds below headline criteria, though variable
wind direction will shift to the northeast by late Sunday as the
aforementioned front eases southward. Periodic bouts of showers will
move in this evening and overnight as moisture streams into the
region. These showers with occasional embedded thunderstorms will
continue through the day Sunday and likely into at least early
Monday before the low departs to the south.
HYDROLOGY...
A large area of low pressure will develop over the central Great
Lakes beginning tonight and persist over the region throughout the
beginning of next week. A warm front will lift northward into
Southeast Michigan this evening allowing moisture and humidity over
the state. Rainfall totals in excess of 1 inch will be possible by
Monday morning. Slow moving shower and thunderstorm activity will be
possible particularly north of I 69 Sunday afternoon. The long
duration of the rain combined with recent dry spell may allow for
ponding on roadways, but no flooding concerns are expected.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....DG
DISCUSSION...CB
MARINE.......TF
HYDROLOGY....CB
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
653 PM CDT Sat Oct 2 2021
.AVIATION.../00Z TAFS/
Scattered convection over the Hill Country appears to lose steam as
they are marching slowly SE toward the SAT area. Will leave no
mention in the TAFs as the loss of daytime heating should reduce
coverage to isolated. Time sections show a fair amount of mid level
clouds that should linger through much of the night. This should
limit the amount of fog to form until we get closer to daybreak. Will
just place a standard 4SM visibility, but there could be a few
pockets of dense fog given the rains received over the past two
events. Much less cloud and vsby considerations are made for DRT
where less rain fell. Light winds are expected through the period,
but some steady breezes up to 10 knots may be possible in the mid
afternoon hours along I-35.
&&
.PREV DISCUSSION... /ISSUED 218 PM CDT Sat Oct 2 2021/
SHORT TERM (Tonight through Sunday Night)...
Early afternoon RAP analysis depicts a closed upper low over KS that
is in the process of opening up as it`s ingested into the nrn stream
flow. A weak cold front extends to its south through eastern OK and
TX and is beginning to very slowly push into our northern counties
this afternoon. Despite an 80 kt 250mb jet moving overhead, rain
coverage along and ahead of the front had actually decreased through
the morning, with only a few isolated sprinkles and light showers as
of 18Z, mainly north of our area. In fact, there`s likely two
separate weak boundaries at the moment, one just north of the
escarpment in our CWA and a second just north of our CWA associated
with the decaying early AM precipitation. Shower activity finally
began to develop along the southern boundary just after 18Z but has
remained isolated. With CAMs continuing to back off on coverage of
this activity through this evening, I`ve continued the trend of
lowering POPs. The best chances today will remain over the Hill
Country and northern I-35 corridor at about 30%. Some slight chances
will remain in the forecast for the Coastal Plains as well, but many
areas are likely to remain dry today with highs in the 80s under a
mix of clouds and sun.
Overnight, a shower or two may linger across southern/southwestern
portions of the region as the boundary hangs around the region and
moisture pools along the Rio Grande. H7 flow out of the NW will push
a drier airmass into the Hill Country, and overnight lows there will
drop into the low 60s. Upper 60s and low 70s are forecast elsewhere.
for Sunday, a few of the CAMs still depict very isolated pop-up
showers. Although there`s not much in the way of large-scale lift to
speak of, slightly more favorable jet streak placement could be some
help. Have opted to carry a broad-brushed 10%POP across the southern
half to two thirds of the area to cover this remote chance. Despite
northerly/northeasterly surface flow, temperatures during the day
will actually be a couple degrees warmer than today for most
locations as a result of some stronger subsidence as high pressure
begins to build in behind the front. Sunday night will be dry with
lows in the 60s to near 70, with a couple low-lying spots probably
dipping into the 50s.
LONG TERM (Monday through Saturday)...
An upper level trough over the Central Plains will dig down into the
southern Mississippi Valley Monday into Tuesday. Central Texas will
be on the backside of this trough and the flow will be northerly to
northwesterly. The low level flow during this time will be northerly
to easterly across our CWA. This combination will keep our weather
dry during the first part of the new week. With the drier air in the
low levels, low temperatures will fall a few degrees while high
temperatures warm slightly. The upper trough over the Mississippi
will close off into a low and this low will drift northward during
the middle of the week. Texas will continue to be on the dry side of
this feature. Low level high pressure will move from near the Texas
Panhandle through East Texas to the Gulf. This will result in light
surface winds. The bottom line will be dry weather continuing through
the latter part of the week. Temperatures, both highs and lows, will
warm a degree or two and be above normal through this time period.
Saturday the low level flow will become southeasterly and moister
air will return to the region, but still no lifting mechanism and we
will stay dry.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 69 90 67 89 62 / 20 - 0 0 0
Austin Bergstrom Intl Airport 67 90 66 90 61 / 20 - 0 0 0
New Braunfels Muni Airport 68 89 67 91 62 / 20 10 0 0 0
Burnet Muni Airport 67 88 63 87 61 / 10 - 0 0 0
Del Rio Intl Airport 71 90 70 91 67 / 10 10 0 - 0
Georgetown Muni Airport 67 89 64 88 60 / 20 0 0 0 0
Hondo Muni Airport 68 90 67 90 62 / 20 10 0 - 0
San Marcos Muni Airport 67 90 65 91 60 / 20 10 0 0 0
La Grange - Fayette Regional 70 90 67 91 62 / 20 10 0 0 0
San Antonio Intl Airport 70 88 69 89 65 / 20 10 0 - 0
Stinson Muni Airport 72 91 70 92 65 / 20 10 0 - 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Oaks
Long-Term...Treadway
Area Forecast Discussion
National Weather Service Grand Forks ND
1010 PM CDT Sat Oct 2 2021
.UPDATE...
Issued at 1010 PM CDT Sat Oct 2 2021
Smoke is lingering in northeast ND and along/west of the
escarpment, however vis has remains in the 5-8sm range (lower
impacts). Fog is starting to develop near Lake of the Woods a bit
earlier than expected, but remains patchy/variable in impacts. I
adjusted timing of fog and left smoke mention only during evening
period. Otherwise forecast remains on track, and will continue to
monitor trends regarding fog coverage/impacts.
UPDATE Issued at 704 PM CDT Sat Oct 2 2021
Smoke overspread the Devils Lake Basin a bit faster with vis
restrictions than HRRR smoke model had indicated, and adjustments
were made to account for this. This may actually spread further
east and eventually get trapped under the nocturnal inversion, so
it will be hard to gauge impacts into the evening/overnight
(additional adjustments likely needed). Rest of forecast still
appears to be on track.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 304 PM CDT Sat Oct 2 2021
Highlights within the short term include potential for fog, some
smoke from Canada moving towards the FA, and seasonably warm
temperatures.
Mid level trough that focused recent rain is pushing east as
a jet streaks noses into the PacNW reintroducing ridging into the
Northern Plains. This is helping clear skies from west to east,
with lingering clouds within Minnesota expected to push east into
central Minnesota by this evening. Surface ridging currently in
eastern North Dakota is expected to influence tonight`s weather
helping keep keep wind light. Recent hi res guidance continues to
favor calm winds within northwest Minnesota.
These calm winds and clear skies should provide efficient
radiational cooling allowing favorable conditions for fog, some of
which may be dense and may present some impact to travel through
limited visibility. A nudging factor towards fog potential will
be antecedent damp soils from recent rain and daytime cloud cover.
Again, currently favored areas for fog will be in northwest
Minnesota outside of the Valley. There remains potential for fog
within west-central Minnesota as well, however confidence is
lessened due to questions on whether winds will remain high enough
to prevent fog, or at least making it more patchy and transient.
Will continue to defer decision towards advisory issuance due to
confidence remaining less than 70% in coverage and better
placement of dense fog, however best timing for potential fog will
be between 2 am - 8 am.
An area of smoke originating from a large fire in east-central
Saskatchewan is moving south-southeast into northwest and north-
central North Dakota. Recent surface observations show this area
of smoke is near the surface with visibilities as low as 1 mile
as seen at Minot. This smoke is expected to push into portions of
the Devils Lake basin late this afternoon into the evening.
Gradual dispersal of smoke is expected tonight.
Otherwise, seasonably warm temperatures with highs well into the
70s are expected Sunday. Combined with ample sunshine and lights
winds, a pretty nice early October day is expected.
.LONG TERM...(Monday through Saturday)
Issued at 304 PM CDT Sat Oct 2 2021
Confidence continues to be high on the evolution of next week.
Ridging over the area is expected to eventually give way to upstream
troughing, bringing southwesterly flow over the region. Primary
impacts expected over the long term period will be repeated breezy
days through midweek and precipitation chances by Friday and
Saturday.
The beginning half of the period will be characterized by large
scale ridging. This ridge is rather transient and won`t stick around
for the entirety of the period. Closer to the surface, given the
position of the ridging, southerly flow will develop over the area.
With the lack of moisture and lack of an airmass change, the
expectation is for mostly clear skies through the week with breezy
conditions thanks to deeper vertical mixing.
Looking ahead towards the end of the period, there is a strong
signal for precipitation by Friday and Saturday. The primary
questions at this point will be position and timing of precipitation
and how much moisture is able to advect as a result of the southerly
flow, so there is something to watch for by the end of the period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 704 PM CDT Sat Oct 2 2021
SMoke is causing variable visibility conditions in the DVL area
and this may start to impact KGFK and KFAR this evening
(confidence is low at this time but should be monitored). Patchy
ground fog with some dense pockets are possible later tonight into
Sunday morning in MN (possibly into southeast ND). Confidence in
impacts is still low as conditions could vary, and I leaned
forecast towards IFR rather than VLIFR at KBJI. Impacts at other
terminals are still too uncertain due to the nature/coverage of
possible fog tonight.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...CJ
LONG TERM...Perroux
AVIATION...DJR
Area Forecast Discussion
National Weather Service Goodland KS
946 PM MDT Sat Oct 2 2021
.SHORT TERM...(This evening through Sunday Night)
Issued at 246 PM MDT Sat Oct 2 2021
The short term forecast is looking to be fairly quiet. The rest of
today will see a mix of clouds and sunshine as the surface low
continues to push off further to the east and higher pressure begins
to move in from the west. By this point, the outer bands of the low
are now southeast of the area and have little to no bearing on the
area. With that in mind, winds and cloud cover are expected to
decrease going into the evening and overnight hours allowing for
clear skies and relatively light winds. With those conditions over
the Tri-State area, lows are forecasted to drop into the low to mid
40`s over the night with a few low lying areas potentially seeing
temperatures in the upper 30`s. Fog could also be possible in some
areas though the westerly component to the winds could limit the
potential for fog to develop.
Sunday, the area remains between the 500mb ridge and trough though
the ridge to the west begins to amplify and start pushing its way
east. Near the surface, relatively high pressure will have expanded
over the area and moisture is forecasted to remain limited with
surface dewpoints in the 30`s and 40`s with 850mb-700mb layer RH
near 30%. Given these conditions, sunny to mostly sunny skies will
be present across the area tomorrow. This will also allow
temperatures to warm into the low 80`s, especially with 850mb temps
near 20C. The warmer temperatures and dry conditions will allow for
elevated to near critical fire weather conditions along and west of
the Colorado border as RH values drop into the mid to upper teens.
Sunday night looks to be similar to Saturday night with clear skies
and relatively light westerly winds. Low temperatures are forecasted
to be a few degrees warmer than the prior night with lows mainly in
the mid 40`s with some low 40`s possible.
.LONG TERM...(Monday through Saturday)
Issued at 212 PM MDT Sat Oct 2 2021
At the start of the period, nearly northerly flow prevails aloft as
upper ridging amplifies along the eastern Rockies. This ridge
progresses east on Monday and Tuesday, centering over the High
Plains between two areas of low pressure (one near Baja California
and one in the southeastern CONUS). Dry weather prevails, with a
potential for near critical fire weather conditions on Monday along
and west of the Colorado border where relative humidities fall as
low as the middle teens. Fortunately, northerly winds appear to be
light at this time.
The Baja California disturbance ejects through the flow on
Wednesday, but precipitation chances look to avoid the region for
now. Beginning on Thursday, the southeast low progresses, allowing
upper ridging to rebuild over the Plains. The ridge persists through
Saturday, resulting in continued dry conditions for the area.
Temperatures remain relatively steady through the long term period.
High temperatures range in the upper 70s to low 80s, while low
temperatures are mainly in the 40s and low 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 940 PM MDT Sat Oct 2 2021
...Optimal Aviation Weather...
Clear skies /VFR conditions/ and light/variable winds are
anticipated to prevail through the TAF period at both terminals.
With clear skies and calm winds, a brief period of patchy fog
cannot be ruled out AOA sunrise.. though HRRR visibility forecasts
are not indicative of fog development.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...KAK
LONG TERM...JBH
AVIATION...VINCENT
Area Forecast Discussion
National Weather Service Grand Rapids MI
600 PM EDT Sat Oct 2 2021
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 318 PM EDT Sat Oct 2 2021
- The primary issue into Sunday is locally heavy rainfall
- Some drying Tue-Wed but rain comes back late in week
- Some suggestion of colder after the 15th
&&
.DISCUSSION...(This evening through next Saturday)
Issued at 318 PM EDT Sat Oct 2 2021
- The primary issue into Sunday is locally heavy rainfall
It is looking much more likely we will see areas of locally heavy
rainfall with isolated thunderstorms tonight into Sunday. The 12z
HREF 24hr LPMM shows numerous patches of 2 to 3 inches of rain
over a good part of our CWA. Several runs of the HRRR and NAMNEST
show 2 to 4 inches in narrow bands but there are numerous such
bands over a good part of our CWA. So, the message is locally
heavy rainfall tonight into Sunday.
What we have is the merging of northern and southern stream
shortwaves into a well developed upper low. The merging begins
this evening but really come together Sunday. We have a negative
tilt upper wave Sunday morning. The 500 to 300 mb Q-Vect
convergence is impressive Sunday morning over Lower Michigan.
Model sounding show the typical nearly saturated sounding to near
300 mb with very skinny cape (typical of a heavy rain sounding).
Winds will be light over a good part of our CWA to over 500 mb
Sunday morning due to the forming of the upper low. That means
storm cells will not be moving much. Given the precipitable water
is in the 1.5 to 1.7 inch range, which is well above normal for
this time of year, all of this fits the idea of locally heavy
rainfall.
Pin-pointing the local of the heaviest rain is more like throwing
a dart. We knew there will be heavy rain but the hi-res models are
not that good that they can tell us 24 - 36 hours out, where
exactly they will be. In this case most of our forecast waring
area has a threat due to large upper level system that is causing
the forcing for lift.
The thunderstorm threat is low since the cape is so narrow but
that is not to say we will not see some thunderstorms but the key
here is the heavy rain more so than any other threat with these
storms. Most of the heavy rain may not come from
thunderstorms,just very efficient rain showers.
Looking at the FLASH soil moisture, it is showing mostly below 50
percent and western sections near and south of I-96 are below 30
percent. So I do not see a major flood threat. This is mostly a
local urban flooding threat.
The heavy rain threat is best Sunday during the day. By evening
the best inflow is east of this area. We will still see showers
around but they will likely not be as heavy.
- Some drying Tue-Wed but rain comes back late in week
Once the upper level system really develops it will sink well
south to near the Gulf Coast in the Tue-Wed time frame. A large
upper high forms north of it (REX BLOCK) over MI/MN. That should
give us some drier weather, but it will still be warmer than
normal as there is really no cold air near us at this point.
The next large scale Pacific system will pick up that upper low
and bring the Gulf moisture back north with it. At this point the
end of the week into the weekend will likely be rather wet but
still warmer than normal. This will be a prolonged event since the
upper low will be worth a few days of rain, but then we will have
a stalled front near us with waves. That will mean maybe 3 to 5
days of periodic shower into early next week.
- Some suggestion of colder after the 15th
We do have a recurving typhoon, what was, Typhoon Mindulle. This
in now a rather impressive storm near Japan. This will help,
through rossby wave interactions, develop a trough over the
central or eastern CONUS by the end of the following week. It is
at that point the cold air may well come into our area, and
possibly be our first widespread freeze. The ensembles of the
GEFS, and ECMWF are now showing this in that time frame.This is
more than 2 weeks away but something to thing about.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday)
Issued at 600 PM EDT Sat Oct 2 2021
A mix of primarily MVFR to IFR conditions is forecast tonight due
to low clouds and areas of rain showers. Conditions will gradually
deteriorate to mainly IFR/LIFR late tonight through Sunday morning
due to lowering cigs as well as scattered showers and patchy fog.
Mainly IFR conditions are forecast Sunday due to low clouds
scattered showers and fog. There is not enough potential for
thunderstorms to warrant mention of it in any of the terminal
forecasts at this time. It is possible that an isolated storm
could impact any of the terminals this evening and again Sunday
(mainly late in the afternoon and early evening). The terminal
forecasts will be updated accordingly as needed as confidence in
any thunderstorm timing/location increases.
&&
.MARINE...
Issued at 318 PM EDT Sat Oct 2 2021
We may have to issue a small craft advisory for Sunday night into
Monday for the north winds on back side of our departing storm
system. However the wind is more offshore than in our near shore
so I through it best to let later shifts consider this as a
possibility.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Laurens
MARINE...WDM
Area Forecast Discussion
National Weather Service Gray ME
1049 PM EDT Sat Oct 2 2021
.SYNOPSIS...
A frontal boundary will remain over New England tonight. This
boundary will bring mostly cloudy skies and occasional showers
into Sunday. Low pressure over the Great Lakes will slowly move
eastward Sunday night into Monday bringing continued chances
for showers possibly lasting into Tuesday. High pressure builds
in towards Wednesday bringing mostly dry weather the second half
of next week.
&&
.NEAR TERM /TONIGHT/...
1045 PM Update...A few more tweaks to PoP/Wx and T/Td trends but
otherwise no change.
700 PM Update... Have a refresh of T/Td along with PoP/Wx
through tonight according to latest trends. This brought down
temperatures a little quicker, though overnight lows are largely
the same given high dew points. Otherwise the forecast is well
on track.
Previously...
Scattered showers will continue across the forecast area
overnight as weak warm air advection in the lower levels of the
atmosphere along and near a frontal system. The latest HRRR and
HREF solutions continue to indicate the highest likelihood for
precipitation overnight will be located over northern and
western portions of the forecast area.
Patchy late night fog cannot be ruled out especially in the
vicinity of the most persistent shower activity.
There will be a wide range in overnight lows tonight with
readings near 40 over far northern areas, but 50s over southern
sections.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
12Z operational and ensemble guidance continues to indicate
that a slow moving and weak area of low pressure will approach
from the Great Lakes region Sunday and Sunday night. Scattered
showers will continue along with mainly cloudy skies. The
chances for precipitation will increase Sunday night as the
system continue to slowly plow east to a position over northern
Ohio.
Highest temperatures will continue to be along and near the New
Hampshire and Massachusetts state border along and south of the
frontal boundary. A few lower 70s can be expected in this region
once again.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Showery for points south and west to start the week with
continued cloudy skies, drier and warmer conditions come mid-
week.
12z upper air analysis shows a upper level low centered just
off the coast of New Brunswick this morning. This low is
forecast to slowly exit NE across the Gulf of St Lawrence over
the next 24 hours, slowing over Newfoundland Monday. NNW winds
in wake of this low will contribute to the advection of dry air
from the north across much of Maine, including western points.
Meanwhile, areas of broad and localized low pressure will
organize over the Upper Midwest this weekend. The area of low
pressure spreads eastward into the Great Lakes come Monday, with
a stationary boundary draped through New England. The area of
low pres will feature a wide conveyor belt of moisture moving
poleward, but without a punchy northerly component, it wont
be able to penetrate the stiff zone of baroclinicity across New
England.
The result of these warring air masses is continued dry
conditions for northern and central Maine, with the ongoing
chance of showers for much of NH and western/southern Maine. Wet
vs dry is likely going to be defined by a sharp gradient. Areas
on the wet southerly side would receive occasional showers, and
the northern dry area receiving much less coverage with a
passing shower. Defining this exact line will come as the low
develops across the Great Lakes over the next 36 hours. Rain
chances increase in central ME as the deformation zone drops
into the eastern Great Lakes Monday evening. This provides a
more decisive push of moisture throughout central New England,
albeit short-lived.
With the amplified upper trough remaining in a positive tilt,
the base becomes cut-off from prevailing flow, meandering across
the Ozarks through mid-week. The weakening of southerly flow is
enough for the northern stream to cozen dry air into the area
Wed thru Fri.
Guidance is fairly scattered when it comes to the weekend. High
pressure will transit the Northeast at the end of the week with
dry weather, but there is a wide spread as to how return flow
and approaching low pres wrapping up into Ontario/Quebec pushes
moisture into New England. As a result, kept precip chances low,
keying mostly on any moist return flow behind the exiting high.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Short Term...A frontal boundary will bring mostly cloudy or
overcast conditions through Sunday night with occasional -SHRA,
mainly over northern and western sections. More widespread MVFR
cigs will be possible tonight particularly at KLEB, KHIE, and
KCON. Cigs will likely lift to VFR Sunday, although MVFR cigs
will still be possible. Conditions lower once again Sunday
night.
Long Term...A period of MVFR/IFR ceilings is possible through
Mon night with -SHRA, improving Tues afternoon for mostly NH
terminals. Conditions may only waver between VFR/MVFR for ME
terminals. VFR for Wed and Thurs with predominately light winds.
&&
.MARINE...
Short Term...A generally easterly flow will continue over the
waters tonight through Sunday night. Seas will continue to
gradually build during the period with a long period swell
continuing. Have capped the seas at 4 feet as large waves are
not being detected near the Gulf of Maine, therefore SCAs will
not be needed.
Long Term...Conditions are expected to remain below SCA criteria
as a stationary boundary lingers over New England through Tues.
High pressure moves into the region through mid-week. Waves
generally expected to be 2 to 4 ft with light winds.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
UPDATE...Casey
NEAR/SHORT TERM...Cannon
LONG TERM...Cornwell
Area Forecast Discussion
National Weather Service Lincoln IL
852 PM CDT Sat Oct 2 2021
.SYNOPSIS...
Issued at 316 PM CDT Sat Oct 2 2021
Showers and thunderstorms will be in the forecast through the rest
of the weekend as a pair of upper level disturbances pass through
the region. Expect showers and occasional thunderstorms to affect
the area through Sunday with periods of heavy rain possible in
areas of thunderstorms. Highs will be in the 70s for Sunday and
into all of next week thanks to a slow-moving upper level low
pressure system.
&&
.UPDATE...
Issued at 852 PM CDT Sat Oct 2 2021
Precip has become more scattered and lots of it has diminished
over most of the area. Cloudy skies will continue over the region
as the upper level wave is still west of the state and will slowly
move east tonight through tomorrow. Scattered showers will remain
possible overnight with an isolated storm still possible under the
upper level low tomorrow. Have made some adjustments to pops/wx in
the grids with the rest of the forecast looking fine. Will send an
update shortly.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 316 PM CDT Sat Oct 2 2021
Showers and thunderstorms will continue into tonight as an upper
level wave moves through the region. Instability is a little
better in northwest IL where the RAP analysis has 1000-1500 J/kg
of MLCAPE. The southeast is around 800 J/kg as of 2 pm. Shear
continues to be less than 20kts...and is expected to stay weak
through this system`s lifetime in central IL. So, severe weather
is not expected. However, with precipitable water at 1.8" or so,
periods of heavy rain will continue to be a concern. The main
upper low is currently over KS and is expected to open up and move
through MO tonight. Showers/thunderstorms will continue to be in
the forecast tonight, with the best forcing from the main wave
coming between 4 AM to noon from southwest IL to eastern
IL...this is also when the surface cold front will push southeast
across the area. Still, instability increases tomorrow afternoon,
and with the upper trough in the area/cool temps aloft, showers
and isolated thunderstorms will be possible again across the
entire region on Sunday. Precipitable water will be closer to
1.25-1.5" on Sunday.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 316 PM CDT Sat Oct 2 2021
The Midwest will transition to a very amplified flow by Monday
with northerly flow across the region as an upper ridge builds
over the central U.S. and an upper wave tries to dive south and
cut off over the Ark-La-Tex region. This upper low stays in this
general area before lifting north up the MS river valley towards
midweek. This upper low will keep cooler temperatures in the
region as well as the chance for shower activity. The upper low
gets caught up in the main east-west flow by the end of the week
and ejects northeastward allowing the zonal flow to return by
Saturday. Temperatures will be warming to around 80 by Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 642 PM CDT Sat Oct 2 2021
MVFR cigs will prevail at most sites and then become dominate
across all sites around midnight...mainly SPI and PIA. BMI, DEC,
and CMI will see cigs drop to below 1kft overnight but then
improve back to MVFR during the morning hours. PIA, BMI, and SPI
will not see VCSH until after midnight, but DEC and CMI will see
VCSH all evening and through the night. All sites will see VCSH
through tomorrow morning and likely in the afternoon, but going to
remove mention of any precip for tomorrow afternoon with FROPA.
Winds will be southwest to light and variable tonight but then
become more southwest tomorrow during the day and then become
west-northwest around noon with FROPA.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Auten
SYNOPSIS...Knutsvig
SHORT TERM...Knutsvig
LONG TERM...Knutsvig
AVIATION...Auten
Area Forecast Discussion...corrected
National Weather Service Jackson MS
958 PM CDT Sat Oct 2 2021
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
A moist and unstable airmass will remain over the ArkLaMiss
region ahead of an approaching shortwave trough and associated cold
front as we go through tonight. While much of the shower/tstm
activity has diminished with nightfall, the approaching ascent has
reinvigorated convective activity just to our northwest over
central AR. So the near term forecast is generally on track with
convective rain chances continuing tonight, and have only made
minor adjustments. It still looks like patchy areas of fog can be
expected over much of the area in the least, but still not sure if
and where there might be more than that. /EC/
Prior discussion below:
Tonight and tomorrow...
High pressure over the southeast is rapidly losing ground to a sfc
low over the Great Lakes and the associated frontal boundary that is
draped through the mid Miss River Valley and back to the southwest.
Southerly flow continues to bring warm air and moisture up into the
region, as a couple waves move into the region, spurring showers and
thunderstorms this morning...only to be replaced by largely
diurnally supported convection this afternoon. Last few HRRR runs
are a little less aggressive with the pop coverage overnight once
the diurnal influence is lost. Given that issue...am concerned about
potential fog development overnight. Winds, or at least the forecast
gusts should help to keep the development from being widespread, at
least in the NE. However, the area most likely to lose clouds is
closer to the tail end of the sfc trough in the southwest...less of
a pressure gradient, less wind overall. Dewpoints are already in the
70s...it won`t take much to see that fog develop once temps drop.
Guidance has been patchy with the fog, and latest HRRR has developed
a swath of very low stratus across the south. Have added patchy fog
in the south and west...but may need to see that expanded.
Tomorrow will be similarly hot and humid with showers and sct
thunder ahead of the approaching frontal boundary. Models are still
somewhat inconsistent with the coverage overall...which will impact
the instability available. For now, looking at forecast
soundings...they are similarly adequate with "skinny" CAPE later in
the afternoon, but the shear is far less impressive.
Sunday night through Friday...
Chances for showers and thunderstorms will continue into Monday as a
cold front approaches and passes through the region. Highs Monday
will climb into the lower to middle 80s. The front and associated
low will stall east of our area, with some wrap around showers
possible Tuesday into Wednesday for mainly eastern portions of the
area. Highs Tuesday and Wednesday will be slightly cooler, mainly in
the upper 70s to lower 80s. High pressure will be building in
Thursday and settling in for the remainder of the week, thus dry
weather can be expected. We will see a gradual warming trend through
the remainder of the week, with highs back in the lower to middle
80s by Thursday and Friday. /27/
&&
.AVIATION...
00Z TAF discussion:
A warm and humid airmass will continue to support showery
conditions with an increased threat for IFR/LIFR stratus and
perhaps some fog late tonight through early Sunday morning. Expect
slowly improving ceilings mid to late morning with increased
convective rainfall coverage during the afternoon, especially over
eastern portions of the forecast area ahead of an approaching cold
front. /EC/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 69 83 66 83 / 56 68 24 37
Meridian 68 81 65 81 / 46 77 45 53
Vicksburg 70 85 66 85 / 68 53 10 17
Hattiesburg 70 83 67 83 / 69 76 34 58
Natchez 68 83 67 83 / 65 44 12 20
Greenville 68 85 65 83 / 58 55 5 12
Greenwood 68 84 64 83 / 60 70 11 19
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
810 PM EDT Sat Oct 2 2021
.SHORT TERM...(This evening through Sunday)
Issued at 348 PM EDT SAT OCT 2 2021
Satellite and RAP 500mb height analysis shows strong blocking
continuing over Nova Scotia and Quebec, where a rex blocking pattern
is in place, with a very slow shift to the east in this feature though
the weekend. An upper level ridge extends from Ontario to
northern Quebec with a weak trough undercutting the ridge over the
western Great Lakes. At the surface a broad area of low pressure
was sitting over eastern MN, WI and the U.P. Light southerly flow
had brought dewpoints into the low to mid 60s and temperatures
overachieved in the west where more sunshine was observed then
expected, with temps reaching into the mid 70s. A cold front was
strengthening somewhat over MN and Ontario which will arrive
tonight, meanwhile a lake breeze was surging inland off Lake
Superior with a few showers developing along the boundary over
Marquette and Baraga counties. Another area of more widespread
showers was over the far east.
Tonight the cold front will push though the area with winds becoming
light and northerly. We will continue to see areas of showers and
possibly a thunderstorms with a relatively messy and weakly
forced environment. Instability is present with MLCAPE of 500 to
maybe 1000 J/Kg along with weak shear, which should support a few
weak thunderstorms this afternoon and evening. Areas of scattered
showers will continue into Sunday and maintained the broad brushed
approach to the PoPs. Additionally, light, moist onshore flow will
bring low clouds into much of the area with fog, drizzle or light
rain in the upslope areas. Temperatures will be cooler Sunday but
it will remain rather humid for October with dewpoints in the 50s
in the west to the low 60s in the east.
.LONG TERM...(Sunday night through Saturday)
Issued at 317 PM EDT SAT OCT 2 2021
The medium range to extended forecast package will consist of an
upper level shortwave trough slowly exiting the Great Lakes area
Sunday night into Monday, and then the remainder of the week will
remain quiet as a ridge amplifies over the region. This will cause
conditions to start out the week with a chance of rain showers,
before trending to dry and above average temperatures for a majority
of the week. Friday into next weekend will bring the next
opportunity for rain showers as a couple of shortwave disturbances
propagate through the Great Lakes region. Long range guidance
continues to trend toward warm weather precipitation regimes, so the
outdoor enthusiasts wanting to hear about early season snow will
have to hold on just a little longer.
As the shortwave disturbance slowly moves to the east Sunday night
into Monday, rain shower activity will begin to dissipate across the
Great Lakes. Energy associated with the shortwave will then sag to
the southeast, and form a longwave trough over the Southeast CONUS
by Tuesday. As this occurs, an amplified upper level ridge will
quickly form over the Southern Plains, and build across the Central
and Northern Plains on the backside of the trough to the southeast.
Also important to note is that a strong Aleutian Low pressure system
will be trekking across the Canadian Rockies toward Quebec from
Sunday into Tuesday. All of this combined leads to a cut off in the
northern stream of jet energy and wave propagation to the east for
weather systems to the south. This is why the longwave trough will
form an occluded low over the southeast CONUS, and the ridge will
then build across the Central CONUS, leading to a dry pattern over
our cwa from Monday into late Thursday. Needless to say, the active
weather pattern will mainly be to our north and south for a majority
of this week.
By Thursday, a negatively tilted shortwave trough will eject out of
the Rockies ahead of a persistent longwave troughing pattern further
to the west over the Pacific Ocean/Western CONUS. This shortwave
will phase partially with the stagnant occluded low from the
Southeast CONUS, and create the next opportunity for rain showers
over Upper Michigan on Friday. A couple of additional shortwaves are
possible from Friday night into next weekend, bringing the potential
for light rain showers once again. Overall, expect a warm and dry
pattern for the first half of the extended forecast, and then an
uptick in the potential for light rain shower activity towards next
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 801 PM EDT SAT OCT 2 2021
Not the ideal conditions for aviation interests as the night
progresses. LL stratus deck is already attempting to build in at
KIWD and KCMX, and can be anticipated that all three terminals
will eventually be dealing with both low ceilings as well as
visbys as fog develops as well. Thunder chances will persist for a
few more hours before waning overnight. Conditions are expected
to improve tomorrow as clouds lift and break, but still could see
some lingering low clouds at least through midday. Winds will be
primarily out of the N/NNE throughout the TAF period, light to
calm overnight, then picking up tomorrow.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 348 PM EDT SAT OCT 2 2021
Northeasterly winds of to 15 to 25 knots are expected tonight and
Sunday with low pressure passing south of Lake Superior.
Thereafter no significant storm systems are expected through at
least Wed with winds below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...NL
LONG TERM...BW
AVIATION...lg
MARINE...NL
Area Forecast Discussion
National Weather Service Paducah KY
237 PM CDT Sat Oct 2 2021
.SHORT TERM...(Tonight through Sunday night)
Issued at 233 PM CDT Sat Oct 2 2021
Widespread shower and isolated thunderstorm activity continues to
pass from southwest to northeast across the forecast area. Flow
from the Gulf of Mexico has brought a very moist airmass to the
lower Ohio Valley, with precipitable water values of 1.8-2.0"
observed via RAP analysis. This will result in locally heavy
downpours through this evening, with minor flooding issues
possible, especially in southeast MO where 1-3+" has already
fallen in the last 36 hours. After a relative downtick late this
afternoon and early this evening, we anticipate another increase
in shower and thunderstorm coverage tonight through Sunday morning
as the H5 shortwave over the KS moves east. Models also show an
increasing H7 LLJ to aide in the upward motion. Can`t rule out a
strong wind gust mixing down tonight over far southeast MO, but
overall the severe risk looks very low.
By Sunday morning, a surface cold front will begin to push from
west to east across the forecast area. This will bring a gradual
wind shift from SW to NW during the day. At the midlevels, a dry
slot will work into SE Missouri, allowing that area to dry out
with a few breaks in the clouds by the afternoon. We anticipate
plenty of wraparound moisture to work its way into locations east
of the Mississippi River from the surface low centered over the
lower Great Lakes. Included slgt/chc PoPs with isolated thunder in
the afternoon hours. Some of this may be more in the way of
drizzle or sprinkles rather than rain showers. By Sunday night,
precipitation will come to an end as the surface low departs to
our east.
Temperatures tonight will only fall into the lower to middle 60s
with plenty of cloud cover. On Sunday, high temperatures will
recover into the middle to upper 70s, but isolated locations in
our northeast counties may struggle to warm much higher than 70
degrees.
.LONG TERM...(Monday through Saturday)
Issued at 233 PM CDT Sat Oct 2 2021
The pattern will be active beginning Monday as a highly amplified
regime starts with a deep trof from the Great Lakes back across the
Ozarks. In time energy within the western extent of the trof will
cause a cut off low to evolve over the lower MS Valley region and
then drift north across the mid MS Valley region through mid week.
The result will be on and off chances of showers and thunderstorms
each day. Overall confidence is above average given decent agreement
from the deterministic guidance to their ensemble mean solutions. We
narrowed the diurnal ranges slightly, but not by much as we
typically see a decrease in clouds at night, more clouds diurnally
driven during the day once a system like this closes off.
&&
.AVIATION...
Issued at 1209 PM CDT Sat Oct 2 2021
Low clouds, rain, and isolated thunder potential will continue
into the 18z TAF forecast period. Low MVFR to IFR cigs are
spreading north and east into the region, already impacting CGI,
PAH, MVN, and EVV. The low cigs will move into OWB shortly after
18z today. Widespread rain showers will continue to impact the
terminals today through tonight. Vsbys should remain low VFR to
MVFR under most showers, though brief reductions to IFR are
possible under heavier activity.
Latest model guidance has reduced the thunder potential, so only
retained a mention of VCTS at CGI and PAH for tonight. Steady
shower activity will gradually end from west to east Sunday
morning as the cold front passes. However, wraparound clouds and
drizzle behind the main low pressure area will persist through the
end of the forecast period at MVN, CGI, and EVV. Southerly winds
of 5-10 kts will continue today, becoming NW AOA 5 kts behind the
frontal passage early Sunday morning.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...DWS
LONG TERM...08
AVIATION...DWS
Area Forecast Discussion
National Weather Service Reno NV
128 PM PDT Sat Oct 2 2021
.SYNOPSIS...
Warm dry conditions and light winds will continue this weekend. A
weather pattern change then appears likely with breezy afternoons,
increased clouds, and a cooling trend starting around midweek.
Precipitation chances may return later in the week into next
weekend along with much cooler temperatures.
&&
.DISCUSSION...
Main changes to the forecast for the upcoming week:
* Increased coverage of smoke/haze Sunday night-Monday AM.
* Less potential for gusty winds above 30 mph next week.
* Rain chances/amounts through Thursday look less promising, with
best overall precip chances Friday-Saturday.
* Raised Sierra snow levels Friday AM-Saturday AM.
For the rest of this weekend, warm and dry conditions will
continue along with light, generally north to northeast winds.
Unfortunately, the HRRR Smoke model shows a few hours of smoke
returning to southern Mono County this evening from the fires
near Sequoia NP, and lighter haze aloft across much of the eastern
Sierra and far western NV. Then for Sunday night-Monday morning,
the model shows increased smoke and haze into more of eastern CA-
western NV as southerly flow aloft sets up. The higher smoke
potential is likely across Mono, Alpine and Douglas counties and
possibly as far north as South Tahoe and Carson City, so those
who prefer open windows in these locations may want to keep them
closed Sunday night.
For next week`s weather pattern change and approaching trough of
low pressure, the highest confidence is for temperatures cooling
down substantially from Wednesday-Saturday. The 80 degree warmth
in the lower elevations now through Monday won`t be coming back
for a while, so enjoy the warm weather while it`s still here.
We`re likely to see highs fall through the 70s for lower
elevations/60s near the Sierra for Wednesday-Thursday, then 60s
for lower elevations/50s near the Sierra for Friday-Saturday.
Longer range guidance is in solid agreement for below average
temperatures into mid-October.
As for the more challenging part of the forecast--where and how
much precip occurs, there appears to be a trend for this trough to
split off the west coast during the Wednesday-Thursday time frame.
We have made some adjustments toward this splitting scenario,
which would reduce precip chances and amounts through Thursday,
although cloud cover is still likely to be widespread. The better
news with this scenario is that the winds would also be less
significant each day from Tuesday-Thursday, more like typical
zephyr gusts of 20-30 mph each afternoon, reducing fire weather
concerns.
By Friday-Saturday, the southern portion of the split trough will
have a better chance to pull in some subtropical moisture,
although it isn`t looking to be a deep or sustained source. While
a general chance of mainly light rain and high elevation snow is
retained for both days, it isn`t looking to be a blockbuster
event. The snow level also is less likely to fall to Lake Tahoe
elevation (our current forecast raises Sierra snow levels to near
8000 feet Friday morning, with the lowest snow level of 7000-7500
feet projected for Saturday morning). Of course, the rain-snow
line will continue to fluctuate due to the wide variance of storm
tracks indicated in the guidance sources, so it is still advised
for anyone planning activities in the Sierra communities to have
some winter gear handy Friday through next weekend. MJD
&&
.AVIATION...
Pleasant flying conditions this weekend, though HRRR smoke models
do indicate some haze across the Sierra and western Nevada Sierra
front today and especially by late Sunday due to the KNP Complex
wildfire. The smoke doesn`t appear particularly thick outside of
areas immediately downwind of the fire, but slantwise visibility
reductions and/or terrain obscuration is certainly possible,
especially in the Sierra from approximately KBAN south. Terminals
most likely impacted include KMMH with a 25% chance for KMEV and
KTVL.
Light winds this weekend will increase a bit for areas north of
I-80 Monday-Tuesday, then across the region Wednesday-Friday as a
colder system moves into the west. At this point, most gusts
should remain near or below 25 kts for terminal sites. This system
could bring rain and snow showers to the region by the end of next
week, though next weekend looks more likely at this time.
-Dawn
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Blacksburg VA
743 PM EDT Sat Oct 2 2021
.SYNOPSIS...
High pressure will provide dry conditions through tonight. A
cold front combined with an upper level low should slowly drift
toward the Mid Atlantic by late Sunday, which will bring
chances of rain throughout the upcoming week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 735 PM EDT Saturday...
Shower chances increase by Sunday afternoon...
Isolated showers developed in the northwest North Carolina
mountains just before 4PM, in an area with more instability as
shown on the MSAS and LAPS analysis where CAPES were 800-1200
J/KG and the Lifted Index was as low as -6. HiRes models show a
bulk of these showers will dissipate by 10PM.
High pressure will head offshore this evening, and clouds will
increase from the west overnight due to a cold front approaching
the Mississippi River. Thus, low temperatures will be notably
milder tonight.
Patchy fog may still be possible in the river valleys on Sunday
morning, but it will not be as dense nor as widespread compared
to this morning due to the increasing clouds. Otherwise, the
cold front and its associated upper level low should head into
the Ohio River Valley. Showers should race ahead of the front
and could enter southeast West Virginia, far southwest Virginia,
and the northwest North Carolina mountains by the afternoon.
However, chances appear low that these showers will reach the
Blue Ridge, so the Piedmont will likely have another unseasonably
warm day with highs in the mid 80s.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 150 PM EDT Saturday...
Wet and Mild Throughout All of Next Week...
An upper low sagging southward into the Midsouth will be the
dominant weather feature for the eastern U.S. throughout all of
next week. Once the upper low settles into the MS/AL/Middle TN
area, it will remain there throughout the week sending deep
moisture and spokes of energy into the eastern U.S. keeping a
very wet weather pattern in place. NBM pops remain very high
averaging 50-80% throughout the entire period. In addition,
thunderstorm potential is much higher than normal for this time
of year, which could result in locally heavy rainfall. Rainfall
amounts for the Mon-Wed time frame appear to be in the 1-2 inch
range, but locally heavier amounts are possible. Given some
uncertainty in the intensity of the upper low and exact location
still somewhat questionable, don`t want to ramp up pops or QPF
any higher than already indicated.
Temperatures will remain at or above normal and dewpoints will
also remain well above normal for this time of year. High
temperatures will remain in the 70s with lows mostly in the 50s
and 60s. Well above normal dewpoints in the mid to upper 60s!
/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- Moderate Confidence in Precipitation Probabilities,
- Moderate to High Confidence in Wind Direction and Speed,
- Moderate Confidence in Thunderstorm Potential.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 200 PM EDT Saturday...
Wet Weather Pattern Likely to Continue into the Weekend...
A broad closed upper low will remain across the Tennessee Valley
and will have to await for stronger energy to evolve in the
western U.S. to finally kick the system out of the area. This is
not likely to occur until the weekend or perhaps even beyond.
Thus, the wet weather will continue. Temperatures will remain
mild with any Canadian air completely cut off from the flow and
the region. However, with decreasing instability and slightly
cooler temperatures from endless cloud cover and precipitation,
the thunderstorm threat appears to be less and hopefully QPF
will be a bit less as well. However, after several days of
rainfall, any heavy rain at this point could be an issue. Will
add mention to HWO, but be rather unspecific at this point given
level of uncertainty.
More confidence in temperatures which will remain above normal
through the period with well above normal dewpoints in the 60s.
Low temperatures will be a good 15-20 degrees above normal in
the 50s and 60s with high temperatures mainly in the 70s, about
10 degrees above normal.
/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- Moderate Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 740 PM EDT Saturday...
Tonight mid and high clouds will increase from the west, so any
low clouds or fog overnight will not be as widespread. For now
have a few hours of MVFR fog in at KLWB and KBCB toward morning.
An approaching cold front will bring lower ceilings and a
chance of showers west of the Blue Ridge by Sunday afternoon.
Have added showers into the KLWB and KBLF TAFs after 22Z/6PM
but latest RAP and NamNest suggest the rain could be anytime
after 18Z/2PM.
Above average confidence for wind.
Average confidence on ceilings, visibility and timing of the
rain on Sunday.
Extended Aviation Discussion...
MVFR/IFR ceilings and visibilities are likely during Sunday
night and Monday as a cold front slowly moves overhead to bring
periodic showers. Wet weather will continue through the middle
of this week. With a surface based wedge setting up through at
least Wednesday, little improvement in flight categories is
expected through Thursday.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...PW
NEAR TERM...AMS/PW
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...AMS/PW