Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/13/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1016 PM EDT Mon Oct 12 2020
A widespread rainfall will develop tonight and continue
into Tuesday afternoon as a front approaches from the west. High
pressure will build in behind the front returning fair weather to
the area through mid week.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 1000 PM EDT...Main update was to lower PoPs/QPF further
based on trends and per 00Z HRRR (thoughts are the NAM remains a
bit too aggressive). Main reasons below remain the same at this
As of 730 PM EDT...Layered H2O vapor loop depicts ample dry air
in place with some hints of the lower layer channel of some
moistening up the past hour. Local 0.5 degree radar scan shows
some weak returns, likely virga, into Dutchess and Litchfield
Counties. A quick look at the 00Z sounding data, quite a bit of
dry air just below H900. So with this update, we will reduce and
delay the onset of PoPs/Wx for next couple of hours.
Thereafter, low level easterly trajectory increases which should
advect in more lower level moisture and approach of upstream
trough for added synoptic lift for widespread wet conditions to
Prev Disc...Widespread rainfall will develop tonight especially
after midnight as ridging across the region retreats and an
upper trough and its associated front approach from the west.
With the surface high over the Canadian Maritimes and the
remnants of TC Delta along the mid Atlantic coast, southeast
flow in the low levels will be strengthening and moisture from
Delta will be tapped. This rain will be beneficial.
East-southeast winds will gusts up to 25 to 30 mph in favored
higher terrain areas especially across western New England and
Expecting lows in the 40s across the area.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Rain will continue well into Tuesday afternoon as the upper
level trough and its associated occluded boundary move across
the region and the remnants of Delta pass well to our south
across Long Island and the Cape Cod. Rainfall will get enhanced
across New England with broad ascent as heights falls across the
region as the upper trough swings through. The rain will taper
off west to east with the passage of the boundary. Having some
lingering pops into the early evening to the east the Hudson
River Valley. Decreasing clouds Tuesday night with some fog
expected. Will be cool Tuesday with highs only in the 50s.
Flow aloft becomes flat while at the surface ridging builds in
and shifts across the region Wednesday. The center of the high
will pass to our south shifting off the mid-Atlantic and
southeast coast Wednesday night. Seasonable temperatures are
expected with light winds and sunshine.
.LONG TERM /THURSDAY THROUGH MONDAY/...
The flow pattern during the long term will feature a broad anomalous
trough centered over the Plains states shifting eastward and
becoming negatively tilted. Locally, the period will start out mild
on the downstream side of the trough axis. A surface low moving
northeastward through Quebec will pump mild air into the region,
with highs forecast to be several degrees warmer than normal.
Showers will gradually increase along the front from west to east
through the forecast area Thursday evening into Friday. The main
source of uncertainty is how sharp the troughing becomes as the axis
pivots into the Northeast. Both the deterministic ECMWF and GFS have
more or less held to their respective solutions over the last
several runs, with the former spinning up a strong cyclone in the
vicinity of Long Island/southern New England as the trough becomes
sharply negatively tilted, while the latter spins up a weaker
cyclone moving into Maritime Canada. Enough confidence at this point
for likely PoPs Friday/Friday night, but with low confidence on the
details. An ECMWF-style solution would present the possibility of
heavy rainfall over portions of the forecast area and perhaps some
snow over the higher terrain, while the GFS solution is more
innocuous. GEFS members show rather good clustering around the
deterministic solution. Not much to say about which camp will be
correct at this point, so will stick to NBM guidance. Temps likely
return to near/below normal behind this system for Friday into next
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Through 00z/Wed...VFR conditions to the north of KPOU as MVFR
ceilings will advance northward the next few hours to KPSF-
KALB-KGFL. As light rain unfolds, ceilings and visibilities will
lower to borderline IFR/MVFR through most of the overnight
period. Of increasing concern, as suggested and briefed from
previous forecast, LLWS from the easterly direction appears to
be an issue as we will add these to the TAFS overnight into
early Tuesday morning around sunrise. Rain/showers will likely
persist most of Tuesday til about mid-late afternoon hours.
Here, conditions will likely remain MVFR with respect to
ceilings and visibilities to VFR.
Winds will be challenge for the Hudson Valley locations where
southeasterly direction less than 10kts, may become northerly
overnight. For KPSF, easterly winds will increase with gusts at
or above 20kts expected. Northwesterly winds evolve during
Tuesday daylight hours.
Tuesday Night: Low Operational Impact. Patchy FG.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Likely SHRA.
Friday Night: Moderate Operational Impact. Likely SHRA.
Saturday: Moderate Operational Impact. Chance of SHRA.
A widespread rainfall will develop tonight and continue into
Tuesday afternoon as a front approaches from the west. High
pressure will build in behind the front returning fair weather
to the area through mid week.
Winds tonight into Tuesday will be easterly around 5 to 15
mph, with some occasional gusts of 25 to 30 mph in favored
higher terrain areas. Winds on Tuesday will shift to the
northwest-west at around 5 to 10 mph.
No widespread or significant hydro problems are expected
through the next 7 days.
Beneficial rainfall overnight into Tuesday afternoon with
moisture from the remnants of TC Delta being tapped. Total
rainfall amounts through Tuesday are forecast to range from
around 1/2 to 1 inch in most locations, with up to 1 1/4 inches
across favored higher terrain areas of the southern Green
Mountains of VT. Brief high rainfall rates at times may produce
some ponding of water on roadways. Some increased river flows
are likely, but are not even expected to reach action stage at
any main stem forecast points.
Drier weather looks to return Tuesday night through Thursday,
which will result in decreasing river flows.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
Area Forecast Discussion
National Weather Service Columbia SC
1038 PM EDT Mon Oct 12 2020
A weak and dry frontal boundary will cross the area Tuesday with
high pressure will building into the region for Tuesday night
through Thursday. Another cold front will move into the area late
Thursday night and Friday with a few showers.
.NEAR TERM /THROUGH TUESDAY/...
The remnants of Delta are now off the Mid-Atlantic coast, but a
trailing cold front extends southwest across the Pee Dee and into
northern/central Midlands. Not much of an airmass change with this
boundary, with more of a northwest to north flow noted behind the
front along with slightly lower dewpoints.
Satellite imagery depicts extensive cloud cover still in place
across much of the area, with some isolated showers mainly along and
southeast of the boundary, affecting portions of the far eastern
Midlands this evening. The deeper moisture should shift eastward
later this evening and overnight, bringing an end to any remaining
showers and allowing skies to at least partially clear. Lingering
low level moisture, light winds and clearing skies should promote
the formation of some fog toward daybreak. The NBM, HRRR and ARW/NMM
all suggest the best coverage north of the front, so have included
mention of areas of fog across the northern/central/eastern
Midlands, with patchy fog elsewhere. Locally dense fog is possible
as well, and conditions will need to be monitored through the night
for potential dense fog advisories. Another mild night is expected,
with lows in the 60-65 range.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
A cold front will cross the forecast area on Tuesday as an upper
trough moves eastward through the Mid-Atlantic region and off the
coast by Tuesday evening. Moisture is quite limited with this front
with PWAT values around an inch or less and decreasing through the
day from northwest to southeast. Cannot rule out an isolated shower
over the eastern Midlands with daytime heating where moisture is a
bit deeper but confidence is low so will continue with a dry
forecast at this time.
Behind the front, a slightly cooler and drier air mass will arrive
as high pressure builds over the region through Wednesday. Surface
high pressure will begin to shift offshore on Thursday as return
southeasterly flow allows moisture to return to the region. Do not
think there will be enough moisture return and lift to result in
showers at this time but pops may need to be added in future
forecasts if the moisture returns quicker or deeper than expected or
if the coastal trough is stronger. So for now will carry a dry
Temperatures will still be on the warm side on Tuesday as the cooler
air will be slow to work in with highs in the 80s. Overnight lows
Tuesday night will range from the mid 50s northwest to lower 60s
southeast. Highs on Wednesday will be cooler ranging from the upper
70s northern Midlands to the lower 70s in the CSRA. Temperatures
moderate a bit on Thursday as flow picks up a southerly component
again ahead of the next upper trough and a more significant cold
.LONG TERM /FRIDAY THROUGH MONDAY/...
A transition to a much cooler and drier period is expected during
the extended period. A digging upper trough over the Great Lakes
and Ohio Valley will drive a cold front through the forecast area on
Friday. The frontal system appears to be a bit limited on moisture
along the front so confidence is low on any precipitation being
associated with the frontal passage as PWATs will only be around an
inch. Will continue to carry slight chance pops mainly across the
northeastern part of the forecast area at this time.
The front will usher in a much cooler and drier air mass as surface
high pressure originating in western Canada will build over the
forecast area Friday night and Saturday and remain in place through
the weekend. Another reinforcing dry front may pass through the
region on Monday with very limited moisture. Temperatures during
this period will be near to slightly below normal for highs and
below normal for lows. Saturday and Saturday night appears to be the
coolest day of the extended period.
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
VFR at all terminals with the exception of AGS, MVFR/IFR
conditions likely until shortly after daybreak.
Skies have cleared across SC/eastern GA, with clouds building in
from the north later on in the evening. Winds expected to
become calm all TAF sites over the next few hours. With
moisture still present in the area and moderate subsidence, fog
is expected to develop at all terminals. High resolution models
are showing a deep surface inversion forming overnight due to
the lack of cloud coverage at AGS/DNL. Due to this, LIFR fog
that has formed at AGS will likely persist until morning.
Conditions elsewhere will start to decrease around 10z.
Considering the calm winds and current radiational cooling at
CUB/CAE/OGB, LIFR vis/cigs are expected prior to daybreak. Winds
should pick up quickly after, so kept MVFR/IFR conditions until
around 15z. Winds will be from the NW later on in the afternoon
EXTENDED AVIATION OUTLOOK...Little impacts to aviation expected
through Friday associated with a dry cold front and high
Recent rain and upstream releases will lead to minor to moderate
flooding along portions of the Congaree, Wateree and Pee Dee
Rivers. For more information, go to weather.gov/cae
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
717 PM CDT Mon Oct 12 2020
Issued at 715 PM CDT Mon Oct 12 2020
The Red Flag Warning has been cancelled this evening as wind
speeds have decreased. Relative humidity have risen and will
continue to increase tonight as temperatures cool.
.DISCUSSION...(This evening through Monday)
Issued at 353 PM CDT Mon Oct 12 2020
A progressive shortwave trough has long since exited to the east,
and the associated cold front has scoured out some clear smokeless
After some pretty good mixing above 800 mb today, wind speeds
should calm down as we begin to decouple and the surface pressure
The flow continues to be progressive and yet another cold front will
come through late tonight (although not nearly as strong as the one
that passed through Sunday evening). Nonetheless this does look like
a dry frontal passage and confidence is high for this. Both the
NAM12 and RAP indicate pressure rises of 3-4 mb/3 hrs behind this
cold front between 09Z and 15Z, so I would not be surprised to
get a 20-25 mph wind gusts from the northwest directly behind the
front Tuesday morning. By afternoon, surface high pressure settles
in and wind will become noticeably lighter. With highs in the
lower 70s and dry weather with light wind, Tuesday afternoon would
be ideal fall weather conditions for many people.
On Wednesday, yet another cold front passage is expected, and this
time, height rises behind the front will be in the 4-6 mb/3-hr
realm. Looks like I will be bumping wind/wind gusts a good 5 mph or
so from the current forecast as we are trending quite breezy. The
ECMWF forecasts wind gusts up to 45 mph for areas just northwest of
the tri-cities for Wednesday afternoon and this looks quite
believable given how dry we look. The highest gusts probably will
not last too long, however, and will shift south with time. Not sure
if we will not see a sprinkle or two at some point Wednesday night
with the potential of a quick-hitting wave, but the ECMWF does seem
to indicate this as a potential.
By Thursday, the jet stream take a notable dip to the south and
will wind up being a chilly day with forecast highs in the 50s.
Winds will lighten up by Thursday night with surface high pressure
settling in, and widespread frost is anticipated.
Dry weather will continue into the weekend, with rather cool-ish
fall weather forecast. The GFS indicates a cold front could come
through to make Sunday and beyond colder than what we have in the
forecast as 850 mb temps are forecast to be near -10C or so. the
ECMWF waits until Monday, and for now, I will side with the later
ECMWF side. If we are closer to the GFS solution, we might be able
to get a dusting of snow Sunday, however.
Monday does look quite windy with strong surface pressure rises
behind the cold front, and although still a little early to be
talking snow, Monday night there could be potential and I suspect
that the potential might be better Monday night as compared to
Sunday night. Anomalously cold air looks like it will potentially
bust through behind the strong cold front on Monday and 850 mb temps
are generally forecast in the -5C to -10C range from ensemble data
for Monday/Monday night. More than cold enough to support snow,
given that we have some precip around. Our highs in the 50s from the
previous forecast may be in jeopardy as this might be relying way
too much on climatology. Hard to tell this far out as timing of cold
air intrusion will mean everything for Monday highs. Nonetheless, if
cold air is in place (and I have high confidence that it will be),
some ECMWF model ensemble members indicate some light snow in our
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 557 PM CDT Mon Oct 12 2020
VFR conditions are forecast through the TAF period. Surface wind
speeds will drop off this evening but remain strong aloft,
leading to several hours low level wind shear. A cold front will
cross the terminals tonight, bringing a wind shift to the
north/northwest. Tuesday morning will see a period of gusty winds
behind the front, but the gradient will relax during the day as
surface high pressure settles onto the plains with winds becoming
light by aftn.
Issued at 253 PM CDT Mon Oct 12 2020
Red Flag Warning looks good. Not much margin for error, but looks
like it will work out as wind gusts should be somewhat more muted
just east of the tri-cities. Next chance of fire weather issues
will be Wednesday as wind gusts pushing 40 mph are possible as
relative humidity drops to critical to near-critical levels.
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
825 PM CDT Mon Oct 12 2020
824 PM CDT
Had updated forecast earlier to remove the remnants of clouds and
showers which moved out of the area by early evening. Current
forecast looks to be in good shape into Tuesday, and no additional
changes are needed at this time.
Surface cold front which moved through the region earlier today
has pushed well east of the area this evening. Surface high
pressure has spread into the lower Missouri Valley in the wake of
the strong disturbance today, with the northeastward periphery of
the ridge axis moving across the Mississippi toward IL late this
evening. Clear skies and a dry post-frontal air mass behind the
front (surface dew points falling into the upper 30s across the
western cwa) have allowed a quick cool-down with the loss of
mixing at sunset, with winds having diminished quickly as well.
Forecast temps in the upper 30s to around 40 (mid 40s in the heart
of the Chicago urban core) overnight appear reasonable given the
scenario. Warm advection begins aloft after midnight already as
the next in a series of quick waves approaches from the northwest
Winds turn southwest by morning, and become breezy/gust after
sunrise. Patchy mid clouds will likely affect especially northern
parts of the cwa late morning through midday, though a good amount
of sunshine will support temps warming back into the low 70s in
most areas with the breezy southwest winds. Peak gusts 30-40 mph
will again diminish quickly toward sunset.
340 PM CDT
Through Tuesday night...
After the active autumn cold front of today, the weather focus in
the short term shifts to the critical fire weather conditions
expected on Tuesday, most notably along and south of I-80.
A continued impressive presentation on satellite imagery of the
trough from the Upper Midwest/western Great Lakes through the
mid-Mississippi Valley. The pronounced slightly negatively-tilted
short wave and associated speed max is moving directly over the
CWA as of 330 PM and the surface cold front has cleared the CWA.
The low-topped convection, even supercellular at times with 1-3 km
rotation noted on adjacent radars, has also cleared the forecast
area. The highest isallobaric component to the wind, associated
with around 4 mb per 2 hr pressure rises, is moving quickly
through the area behind the cold front. The highest gusts of
around 35 mph (earlier 40-45 mph) are limited in spatial extent
and duration, likely due to lingering stratus. There have been
spotty gusts to 30 to 35 mph in the immediate clearing area
moving into north central Illinois.
Winds will continue to abate this evening and with the drier
air mass and the cold advection from this afternoon, allow
temperatures to drop at decent haste. Winds look to turn
southwesterly late and start inching up especially in north
central Illinois. Before that though some outlying areas could
dip into the mid 30s and realize patchy frost.
Tuesday will find another progressive short wave trough scooting
across the international border ahead of a 115 kt jet maximum.
While the surface low of around 1000 mb will be well north near
Lake Superior, the translating pressure gradient will induce
pressure falls across the area coincident with peak heating. The
925 mb temperatures of 14-15C over the area are easily supportive
of temperatures into the mid 70s especially in the presence of
warm advection and a dry lower troposphere. Model soundings
continue to support the boundary layer effectively mixing, with
southwest gusts of 30-35 mph and probably isolated 40 mph. One fly
in the ointment hinted at is some mid to high clouds, but the
pattern would favor those to remain mainly over Wisconsin.
With the forecast profiles, dew points should mix down at least a
few degrees in the afternoon, with RAP and NAM guidance keying in
the southeastern half of the forecast area to even flirt with
lower 30s dew points. These values provide relative humidities of
20 to 30 percent, with more than enough winds for critical fire
weather conditions. Rain values today were primarily 0.15 to 0.40
of an inch, which with recent dry conditions and low fuel moisture
values beforehand may just dry out very quickly Tuesday morning.
Did consider a Fire Weather Watch but confidence was not there for
that at this time, but confidence is high in at least near Red
Flag Warning conditions especially south. Will continue to
message windy and dry conditions in the Weather Story and ramp up
additional points to consider canceling any planned burns.
340 PM CDT
Wednesday through Monday...
Expecting another breezy day on Wednesday as winds increase out
of the southwest ahead of developing low pressure system and
associated cold front across the upper Midwest. With ample warm
air advection, expect temperatures to warm into the 70s for most
areas. The trailing cold front will push across the area overnight
with low rain chances developing behind the front early Thursday
morning and increasing through the afternoon.
As the low departs to the northwest on Thursday a cold airmass
will advect over the Great Lakes region with high temperatures in
the 50s expected across the local area Thursday and Friday. Low
temperatures may drop to near freezing for areas outside of the
Chicago metro on Thursday where some areas could see their first
freeze of the season. Slightly elevated winds Thursday night and
increasing cloud cover Friday night may limit our widespread
freeze potential, however.
Plenty of model variability remains for for the upcoming weekend,
but generally expect cool conditions to continue through the
remainder of the extended with the upper trough close by.
400 PM CDT
Gusty winds and both dry air and fuel moisture on Tuesday will
support critical fire weather conditions, possibly to the level of
a Red Flag Warning...mainly along/south of I-80. Confidence is
high in sustained surface-to-20 ft southwesterly winds of 15-20
mph with surface gusts at least to 30 mph (some to 35+ mph
possible) especially earlier in the afternoon. Our confidence
also is high in relative humidity dropping to around 25 percent
along and south of I-80, and may do so even north. The fuel
moisture is a little more in question only because of today`s 0.15
to 0.40 inch of rain, though that is already getting some drying
the rest of today and will also dry in the morning thanks to sun
and increasing winds. One question is if the highest winds and
lowest humidity can overlap in the afternoon, at Red Flag
conditions if they occur may only be brief.
Fire weather partners should monitor the latest fire weather
forecasts (FWF) closely into Tuesday, as well as Wednesday which
will also be breezy and dry, and consider any extra precautions
that will be needed.
For the 00Z TAFs...
Aviation forecast concerns:
* Strong west-southwest winds Tuesday with gusts around 30 kt.
Surface cold front which moved through the terminals earlier today
has moved well east of the forecast area early this evening. As
expected, skies have cleared quickly in the wake of the strong
mid-level wave associated with the front. Clear skies, much drier
air and loss of mixing as sunset approaches is already resulting
in a quick decoupling of the boundary layer and a fast drop off in
winds. West northwest winds 10 kt or less will gradually shift
light southwest later tonight.
The next in a series of quick-moving weather disturbances will
approach the region early Tuesday, with southwest winds increasing
and becoming gusty during the morning. Strongest winds are likely
midday into the afternoon, with gusts around 30 kt likely during
the hours of peak diurnal mixing. Some patchy mid-level cloud
cover in the 12-15 kft layer are expected, and if these are
thicker or more expansive than anticipated it could limit peak
wind gusts somewhat, or at least make them more sporadic. Winds
are expected to gradually diminish and turn westerly late in the
afternoon, before shifting northwest by early evening as the
surface cold frontal trough moves through. Winds should again
diminish quickly with sunset. No precipitation is expected with
this frontal passage.
LM...Small Craft Advisory...Burns Harbor to Michigan City IN until 1 AM Tuesday.
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Las Vegas NV
858 PM PDT Mon Oct 12 2020
.SYNOPSIS...Dry warm weather will continue the next several
days under a persistent area of high pressure. Temperatures will
remain 5 to 10 degrees above mid October normals.
.UPDATE...Light winds, clear skies and above-average temperatures
continue this evening. HRRR Smoke as well as satellite imagery from
this afternoon indicated a smoke plume making its way down into the
Owens Valley late this afternoon. That said, observations at Bishop
Airport have not dipped below 10 statute miles, and area webcams
indicated that the smoke layer was decently lofted just before
sunset. Lofted smoke expected to continue through the rest of the
evening, sink to the surface and lower visibility through the
overnight hours in Owens Valley. Forecast looks to be in good shape
tonight; no changes necessary.
.PREVIOUS DISCUSSION... 200 PM PDT Mon Oct 12 2020/
.DISCUSSION...through next Monday.
Very little change in the warm dry weather pattern is indicated the
next several days and no significant weather impacts are expected.
This is due to a persistent ridge of high pressure extending from
the Eastern Pacific over the Desert Southwest. We will see a few
subtle changes such as north breezes filtering down through southern
Nevada and the Colorado River Valley Thursday in response to a fast
moving disturbance brushing the Great Basin as it moves down the
front side of the ridge into a deep trough over the central U.S.
This will be accompanied by high temps dropping 5-7 degrees Thursday
and Friday. Temperatures then climb a few degrees over the weekend
under the dry northwest flow aloft.
.AVIATION...For McCarran...Winds will remain light and follow near
to diurnal trends for the period, remaining below 10 knots. Mostly
clear skies expected through the period.
For the rest of southern Nevada, northwest Arizona and southeast
California...Other than some northerly breezes down the Colorado
River Valley, look for winds to remain under 10 kts through Tuesday.
Smoke from California wildfires is once again expected to work into
the Owens Valley overnight with vsby potentially dropping to around
5-6SM through 15Z before increasing.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter