Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/28/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
900 PM CDT Sun Aug 27 2023
.UPDATE...
Issued at 858 PM CDT Sun Aug 27 2023
Given 18z guidance and upstream dewpoints, decided to drop
overnight lows just a smidgen, especially in NE SD. It does
appear that convection over southwest SD should stay mainly west
and south of the forecast area tonight.
&&
.SHORT TERM...(This Evening through Monday Night)
Issued at 230 PM CDT Sun Aug 27 2023
Overall dry weather expected for the short term with high confidence
on cooler temperatures for Monday. Northwest flow continues over the
Northern Plains with a ridge to our west and a trough to the east.
Within this flow, RAP indicates shortwave energy will continue its
northwest to southeast track over the Northern Plains late this
afternoon and into tonight and drier air moving in behind it into
Monday. At the same time, the surface low/trough will continue its
track across the state and moving out of the CWA by Monday morning.
By early Tuesday morning, mid-level winds become more northerly.
A few light showers/virga were noted across the Mobridge area this
morning. Around 1PM, additional isolated showers/storms did form
across Stanley/Hughes, pushing southeast where they are becoming
weaker, so I added in 15% pops earlier to make up for this as CAMS
have come together a little better now and agree on the continuing
threat through ~22Z. The low is positioned over west central ND with
a surface trough extending southward over much of the state. Cape
values per HREF/Mesoanalysis are around ~1000-1500 J/KG as warm
southerly flow continues and dew point values in the upper 50s to
the lower-mid 60s. However, there is lots of dry air in place in the
lower half of atmosphere and CINH. 2 PM mesoanalysis show -150 to
-300 J/KG over much of our CWA, which is helping kill off the threat
for additional storms this evening, even with 30kt bulk shear/CAPE
over the area. 700 mb temps range between 7-9C and 850mb temps
between 18-20C by 00Z Monday. Otherwise, dry weather expected Monday
through early Tuesday due to high pressure over the area. Lastly
with the mid-level winds blowing from the northwest then turning
northerly, HRRR vertically integrated smoke does show smoke aloft
drifting in from the northwest Monday afternoon through at least
early Tuesday, so added in 30% cloud cover during this time to make
up for this.
Overnight lows will range in the upper 50s to the lower 60s and with
CAA in place for Monday, highs will be cooler than today, ranging in
the lower to mid 80s. Patchy fog could be possible along the ND/SD
border and/or northeastern SD overnight per Rap soundings. Did not
add these to the grids but might as well mention the possibility of
it.
.LONG TERM...(Tuesday through Sunday)
Issued at 230 PM CDT Sun Aug 27 2023
Upper ridge axis looks to build from the High Plains and northern
Rockies on Tuesday, then eastward into the Dakotas by 12Z Wednesday.
This will likely lead to dry conditions and warm temperatures. Will
be watching how models/ensembles trend with the shortwave energy
riding eastward along the international border Wednesday night
through Thursday night, which acts to dampen the ridge over the
Northern Plains. After this feature departs, signals are there for
the upper ridge to build once again over the central CONUS. Towards
the end of the extended period, 12Z deterministic EC showing 850mb
temps climbing back up into the +20s C, which would lead to some hot
temperatures in the 90s once again over the area. Inherited temps
for next Sunday does show quite a few 90s across the CWA. As for
precipitation, mainly dry conditions continue in the forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 609 PM CDT Sun Aug 27 2023
Terminals KABR,KATY,KPIR,KMBG
VFR skies/vsbys are expected regionwide through tonight.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...MMM
LONG TERM...TMT
AVIATION...TDK
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1109 PM EDT Sun Aug 27 2023
.SYNOPSIS...
Any isolated showers will diminish this evening,
allowing for a comfortable overnight with some patchy fog.
Temperatures will be close to normal on Monday with a few late day
showers possible. An upper level disturbance will allow for a
better chance for showers for Tuesday into Tuesday night, with
comfortable and pleasant weather expected behind this system for the
second half of the week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1050 PM EDT...Only minor adjustments needed for this
evening update. Temperatures continue to cool into the 50s and
60s with lowering humidity values thanks to clear skies and
light northerly flow. GOES16 night fog channel shows some low
stratus developing over the higher terrain areas with marine
stratus advecting into coastal CT from the Long Island Sound.
Depending on how quickly the stratus arrives, radiational cooling
should support some patchy fog development, especially in valley
areas. While RAP forecast profiles are not favoring fog
development, current observations show temperatures approaching
their respective dew point so some patchy fog should form.
Previous discussion...Our upper level trough continues to exit
into the Canadian Maritimes with just a few isolated showers
still lingering within the southern Adirondacks and its
foothills. These showers should diminish with the lose of
daytime heating and as weak shortwave ridging builds over the
region.
Skies will turn mainly clear for a period this evening as the
ridging builds into the area and high pressure expands eastward
out of the Great Lakes. This should promote a period of good
radiational cooling through about Midnight or so and allow
temperatures to cool into the 50s and 60s. Light northerly
winds should also help dew points drop further into the 50s.
With enough lingering low-level moisture around, some patchy
fog is expected to form overnight in the typical valley and
sheltered locations.
However, a boundary to our south will lift northward
as a warm front late tonight with warm air advection ensuing in
the low-levels. The combination of WAA and winds shifts to the
southeast advecting marine moisture inland should support a low
stratus deck developing. Low stratus should push inland from
southeast to northeast towards the pre dawn hours. Incoming low stratus
should reduce fog development so we trimmed back fog south of
I-90. Areas north of the interstate should have a longer window
for radiational cooling to support patchy fog, mainly river
valley areas.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
High pressure will be sliding off to the east on Monday. After a
dry and mainly clear start to the day, clouds will be increasing
by afternoon. With a weak disturbance approaching from the west,
a few light showers are possible for western areas by late in
the day or the evening hours, as some moisture starts to return
thanks to the returning southerly flow. Highs should be close to
normal with temps well into the 70s to near 80 in valley areas
on Monday.
On Monday night, there will continue to be the threat for a few
brief light rain showers, especially for western areas, thanks
to the approaching cyclonic flow. Otherwise, skies will be
partly to mostly cloudy with lows in the mid 50s to low 60s.
A sharpening upper level trough over the Great Lakes will be
approaching from the west on Tuesday. Surface cold front
associated with this system will also be moving towards the area
from the west. Meanwhile, another stationary front will be
located just off the eastern seaboard as well. Abundant moisture
will be surging northward, although the highest PWAT area will
be located closer to the stationary front along the immediate
eastern seaboard. Through the day on Tuesday, the best chance
for showers will be far western areas (closer to the approaching
upper level disturbance) and far southeastern areas (closer to
the coastal front). The rest of the area will stay mainly dry
through the day, although a few spotty showers can`t be totally
ruled out, along with a partly to mostly cloudy sky and temps
once again close to normal levels. Dewpoints will be creeping up
through the 60s, so it will feel a little muggy out.
The best chance for widespread showers looks to be on Tuesday
night, as the upper level disturbance and surface cold front
head across the area. At this point, there should be a few
rounds of light to moderate showers and precip doesn`t look
repeated or intense enough to cause any hydro issues, as the
heaviest downpours will likely remain south/east of the region
closer to the coast or offshore. Otherwise, it will be cloudy
and muggy on Tuesday night with lows in the 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Depending on the exact speed of the upper level trough, some
lingering showers may continue into Wednesday (especially in the
morning and for eastern areas). Otherwise, clouds will be giving
way to more and more sun through the day and dewpoints should
lower back down into the 50s by afternoon. Daytime highs look to
be in the 70s on Wednesday with a strengthening northwesterly
breeze developing.
It looks to be a cool night on Wednesday night, although just
how cool it gets will depend on cloud cover and if the breeze
lets up. For now, have lows ranging from the mid 40s to mid 50s
although there is the potential for even colder temps if ideal
radiational cooling occurs.
For the rest of the week into the weekend, the weather is
looking mainly quiet. High pressure should keep it dry with a
partly to mostly clear sky. Temps will moderate towards normal
for the end of the week across the region. Next chance of
any rain may be by Sunday, when a moisture starved northern
stream shortwave could allow for a few brief rain showers.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Conditions are currently VFR across the region
with largely clear skies aside from a few persistent low cu over
higher terrain west of the Hudson Valley, and light north to
northeast winds. Conditions remain VFR through this evening with
winds becoming calm to light and variable.
The development of any fog/mist versus low stratus tonight remains
somewhat uncertain. Current northerly flow has lowered surface
humidity which could inhibit fog/mist formation despite relatively
clear skies. However, a boundary approaching from the south will
bring modest warm advection and increased low-level moisture,
possibly enhancing fog/mist or alternatively resulting in low
stratus. At this point, GFL appears to be the most likely terminal
to see restricted vsbys, and have included prevailing MVFR with
TEMPO for IFR from roughly 06-12Z. Other terminals may see brief
reductions in vsbys to MVFR from patchy fog/mist, and will otherwise
see sct-bkn stratus at 1-3 kft. PSF is the most likely to see IFR
cigs with stratus below 1 kft. Any fog/mist will quickly dissipate
after sunrise.
After 12-15Z, winds increase out of the south at 4-8 kt with sct
clouds at 2-4 kft, while POU may see enhanced clouds with VFR cigs.
Have included VCSH at ALB/GFL after 18Z due to the potential for a
few showers north and west of Albany.
Outlook...
Monday Night: Low Operational Impact. Slight Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday: Low Operational Impact. Breezy. Slight Chance of SHRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Frugis
NEAR TERM...Frugis/Speciale
SHORT TERM...Frugis
LONG TERM...Frugis
AVIATION...Picard
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
1010 PM CDT Sun Aug 27 2023
.UPDATE...
Issued at 1008 PM CDT Sun Aug 27 2023
Earlier showers/storm dissipated around mid-evening, with quite
weather now throughout the area. Expect this to continue through
the night.
UPDATE Issued at 607 PM CDT Sun Aug 27 2023
Some echos are starting to show up on radar along a boundary that
is sagging through south central North Dakota over northern
Burleigh County into Kidder County, in an area where some elevated
instability is noted. Though do not expect this to last long, have
added isolated showers/thunderstorms to the forecast for a few
hours over this area.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 157 PM CDT Sun Aug 27 2023
Quiet through the short term period and possibly smoky.
Currently, a weak surface trough extended from around the Turtle
Mountains, southwest through Bismarck and into western South
Dakota. Winds were north to northwest behind the trough with
temperatures mainly in the mid to upper 80s. Ahead of the trough
winds were southerly with temperatures in the upper 70s to lower
80s. Skies were sunny across the forecast area.
Weak high pressure builds over the forecast area tonight and
remains through Monday. Monday will be slightly cooler than today
with generally light winds. The flow aloft looks to be north
northwest from Canada. Wildfire smoke from Canada (currently
limiting visibilities over central Saskatchewan) will make it`s
way south into the state later tonight and Monday. With the light
surface flow it`s uncertain as if the surface smoke makes it into
the state. There are indications from the RAP that Near Surface
Smoke could approach the area later on Monday. With the favorable
upper level flow, it looks like smoke aloft will be moving into
the area, and earlier. Possibly later tonight. If sufficient
amounts of smoke aloft and near the surface do make it into the
State, high temperatures could be affected somewhat on Monday.
.LONG TERM...(Monday Night through Sunday)
Issued at 157 PM CDT Sun Aug 27 2023
The main feature in the long term period will be an upper level low
pressure system that moves into northeast Montana by Wednesday
afternoon, and then lifts into southern Canada and tracks eastward,
just north of the International Border through Thursday afternoon.
This will bring the possibility of the following impacts:
1) Possible fire weather concerns west Wednesday afternoon into the
early evening. This will be due to a combination of low humidities
and strong winds. Then possibly in the southwest/south central on
Thursday, also due to a combination of strong winds and low
humidities. 2) Isolated to scattered showers and thunderstorms
tracking west to east across the forecast area Wednesday afternoon
through Wednesday night, then mainly along the northern tier
counties on Thursday. Although there is a question as to the
extent of moisture and instability, there should be moderate to
strong shear in place if convection does develop. The latest CIPS
severe probabilities does show a low probability of severe storms
along the Montana Border centered around 00Z Thursday. 3) Strong
environmental winds leading to breezy to windy conditions; out of
the south ahead of the system Wednesday and then westerly winds on
Thursday (especially southwest and south central) as we remain
within the warm/dry sector while the storm system remains to our
north. We will continue to monitor as to the extent of each of
these possible impacts.
Ahead of this system, there continues to be moderate to high
confidence of a warming trend with mainly dry weather into
Wednesday. However, depending on the amount of smoke (surface and
aloft) that ends up over the area, temperatures could be a bit
cooler than forecast on Tuesday. With the surface and upper level
flow shifting as we head into Wednesday, smoke concentrations will
diminish.
Then behind the system, there may be a slight warm-up behind the
exiting upper low, but there is a definite increase in the spread
of NBM ensemble temperatures through the weekend, so confidence
is low in anything more than a modest warm-up through the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 607 PM CDT Sun Aug 27 2023
An isolated shower or thunderstorm will be possible this evening
over south central North Dakota, possibly affecting the KBIS
terminal. Otherwise, VFR conditions are expected.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...JJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...JJS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
810 PM MDT Sun Aug 27 2023
.UPDATE...
Issued at 809 PM MDT Sun Aug 27 2023
Earlier initiated outflow boundary from storms over Northern
Colorado has pushed all the way out over southwest Elbert and
Lincoln counties where a line of convection continues. The line of
storms has weakened a little and will continue to push out of
Lincoln county by around 10 pm. These storms are producing mainly
moderate to heavy rain, gusty winds and small hail. Elsewhere,
next bout of storms pushing back into far northern Colorado of
Larimer and Northwest Weld counties, and this likely associated
with main frontal boundary moving southward. This next round of
showers will produce brief moderate to heavy rain and gusty winds
to 45 mph. Even further upstream showers will dictate to keep at
least isolated to scattered chance of showers in the forecast for
much of tonight. Behind the cold front, expect some areas of
stratus to develop later tonight and into Monday morning. Will
make some changes in the forecast to coincide with latest trends.
&&
.SHORT TERM...(This evening through Monday)
Issued at 147 PM MDT Sun Aug 27 2023
Showers and thunderstorms will continue to progress southeast
across Colorado for the rest of this afternoon and into this
evening. Brief heavy rain, small hail, and winds to 50 mph will
accompany the stronger storms. A severe thunderstorm or two can`t
be ruled out. It`s not well defined, but appears there is a short
wave trough moving into western Colorado. This will provide lift
for the convection. It is also to produce additional showers and
weak storms through the evening, and possibly after midnight.
For Monday, a weak cold front pushes in from the north early in
the morning. Models generally show scattered showers forming
behind the front during the morning hours. Areas along and in the
foothills should see a better chance for showers due to the
upslope flow. If temperatures can warm into the mid to upper 70s
tomorrow afternoon. ML CAPE should reach 500-800 J/kg. The RAP and
NAM show a little more CAPE than this during the afternoon. Some
uncertainty we see enough sun to reach these temperatures. Though
if we do, scattered to numerous storms are expected with small
hail, heavy rain, and gusty outflow winds.
.LONG TERM...(Monday night through Sunday)
Issued at 230 PM MDT Sun Aug 27 2023
A shortwave trough moving through our area on Monday night will
keep a few showers and storms ongoing into the evening hours.
These will mainly be to the south of I-70. As instability fades a
couple hours before midnight, the showers and storms will come to
an end.
The aforementioned shortwave trough will move southeast of our
forecast area on Tuesday with subsident flow building in overhead.
700 mb temperatures will start warming up a bit but highs will
stay a few degrees below normal. Denver will see a gorgeous 82 for
a high with plenty of sunshine. Only a stray shower or storm may
form in the mountains while the rest of the CWA remains dry.
Zonal flow aloft will develop on Wednesday as our forecast area
will be under subsident flow due to the right exit region of a jet
streak being overhead. 700 mb temperatures will warm to around
17-18C across the I-25 corridor which correlates to highs in the
low 90s. The subsident flow will keep conditions dry and it will
also feel hot because there won`t be much cloud cover.
A shortwave trough passes well to the north of Colorado Wednesday
night into Thursday. It attempts to bring a cold front into
Colorado but warm air advection quickly wipes out this front.
Therefore, warm conditions will prevail on Thursday with highs in
the 90s across the plains. There will be better moisture in place
and afternoon showers and storms are possible mainly across the
higher terrain.
A ridge aloft will strengthen over the Central Plains and will
keep the trough along the West Coast of the US from moving
eastward on Friday and into the weekend. The stretch of warm
weather will continue with isolated afternoon and evening showers
and storms possible each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 549 PM MDT Sun Aug 27 2023
Scattered showers and storms continue in and around the terminals
this evening following a strong outflow boundary from the north.
Activity expected to diminish after 01z but still enough upstream
moisture/scattered storms to at least keep a VCSH in the forecasts
through the rest of the evening. A weak cold front will move
southward later tonight with reinforced northerly flow and some
lower stratus (mainly MVFR cigs) expected to develop and continue
through Monday morning. Looks like another round of
showers/storms Monday afternoon.
&&
.HYDROLOGY...
Issued at 230 PM MDT Sun Aug 27 2023
Precipitable water values will be 120-170 percent of normal today
and again Monday. Expect the stronger storms to produce heavy
rainfall with up to 1 inch 30 minutes. Storms will be moving
southeast at about 20 mph. This will keep the flash flooding threat
on the low side and mainly limited to flood prone areas (burn &
urban areas).
There will be much drier conditions in the long term period.
Tuesday and Wednesday will be dry so there is no flash flood
threat. A very limited threat of flash flooding is possible
Thursday into the weekend as weak storms are possible over the
burn areas.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Entrekin
SHORT TERM...Meier
LONG TERM...Danielson
AVIATION...Entrekin
HYDROLOGY...Meier/Danielson
Area Forecast Discussion
National Weather Service Grand Forks ND
1037 PM CDT Sun Aug 27 2023
.UPDATE...
Issued at 1029 PM CDT Sun Aug 27 2023
Trough moves through Ontario overnight, with a weak frontal
boundary over NE ND. Majority of forcing remains toward Ontario
and SE Manitoba, but there still exists a low chance (<10%) for a
brief shower overnight near the International Border. We have
seen this already occur earlier in the night in southern Manitoba.
However, as these showers develop they quickly diminish within an
hour. Patchy fog is possible overnight as winds turn light and
variable, but chances are low at this time.
UPDATE Issued at 625 PM CDT Sun Aug 27 2023
Increased POPS near the Cando and Langdon area as we have isolated
pulse nature storms up in Manitoba shifting SE. We will monitor
these storms as they move closer to the area, but no severe
weather is anticipated. Otherwise, high level smoke continues to
move into the area, with concentrations increasing tomorrow and
Tuesday.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 237 PM CDT Sun Aug 27 2023
Key Messages:
-Seasonal temperatures and minimal precipitation chances today
and Monday.
-Upper level smoke returns late today and persists into Monday.
Impacts are not expected today or Monday in the wake of a weak cold
front. Temperatures will be within the range of seasonal normals
with highs in the 70s to low 80s and lows generally in the 50s.
Winds are expected to remain northerly through the rest of today and
tonight, then begin shifting to the west late Monday afternoon.
Looking at precipitation chances, HREF shows little support for
anything more than a passing light shower in portions of northwest
Minnesota late this evening. Most CAMs are dry, with the HRRR
showing only an isolated shower or two in far northwest Minnesota.
The scenario is very similar for Monday, with the FV3 being the only
model with any shower activity in the region.
.LONG TERM...(Tuesday through Sunday)
Issued at 237 PM CDT Sun Aug 27 2023
Key Messages:
-Impact chances are minimal through next weekend.
-Showers and thunderstorms are possible Thursday.
A northerly H5 flow pattern prevails Tuesday and Wednesday, then
becomes more zonal by Thursday and Friday. Generally quiet weather
is expected through Wednesday, along with seasonal temperatures.
A shortwave is indicated in both the ECMWF and GEFS ensembles as we
head into Thursday. This will carry our only chance for
precipitation during the extended forecast period. Moisture will be
relatively limited during the shortwave passage, with a 15 to 20
percent chance of amounts exceeding 0.25 inches. The current
clusters keep the best chances for higher amounts to the north and
west of the CWA. Temperatures will climb into the 80s on Thursday,
then fall back toward the upper end of normal values for Friday.
H5 ridging is expected to briefly build into the western portions of
the region late next week, then drift eastward. While the timing may
change, ensemble agreement is somewhat high. As such, a return to
warmer than average temperatures are supported next weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1029 PM CDT Sun Aug 27 2023
VFR conditions overnight, with winds becoming light and variable.
There is a low chance of patchy fog in low lying areas. Chances
diminish once sunrises and winds become steady out of the north
around 14-16z. Before winds turn toward the north, there is a low
chance for weak LLWS as a weak boundary shifts through 06-10z.
Otherwise, sustained winds around 10-15kts for all sites
throughout the afternoon hours before turning light and variable
once again at the end of the TAF period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Spender
SHORT TERM...Lynch
LONG TERM...Lynch
AVIATION...Spender
Area Forecast Discussion
National Weather Service Glasgow MT
245 PM MDT Sun Aug 27 2023
.DISCUSSION...
AFTERNOON UPDATE:
Overall, much of the going forecast is still on track. Above
normal temperatures will continue over the next couple days before
the cold front bumps us back down to more seasonable weather and a
chance for some thunderstorms.
One of the more significant changes with this forecast
update was the progression of smoke into the area from northern
Alberta. Smoke is now expected to come in earlier and stronger
Monday morning and impact a more widespread portion of
northeast Montana. Given the modeled near-surface smoke
concentrations, there is concern for significant reductions to
air quality and visibility Monday into Tuesday.
The furthest extent of current RAP smoke guidance shows a
continuing trend of smoke lingering in the area through Tuesday
morning. Even though guidance does not go out further, more than
likely the smoke will be pushed out and dispersed with the arrival
of the cold front Tuesday evening into Wednesday.
Another change of note with this update was the diminishing fire
weather threat for both Tuesday and Wednesday. At this time
yesterday, there was a much more robust concern for elevated fire
danger. But since then, ensemble guidance has continued to trend
RH values up on Wednesday which is expected to be the windiest day
of the week. The fire danger on Tuesday is also trending towards
a more marginal threat that is less widespread than what has been
observed in previous model runs. Phillips and Petroleum counties
still carry the highest risk but fail to reach a threshold that
would warrant any fire weather products at this time. For now,
generalized fire weather concerns will persist as, given the dry
fuels in the area, any fire that starts will have the potential to
spread quickly even with otherwise higher RH values.
-thor
MORNING DISCUSSION:
Today through Tuesday:
There is little in the way of weather in the near term, with above
average temperatures remaining in place beneath an upper level
ridge. The 21Z and 03Z RAP model have maintained a similar setup
for Monday afternoon. They are bringing in moderate to high smoke
conditions near the surface starting around late morning today
near the Canadian border. This smoke will likely filter southward
as far south as northern Wyoming. Current guidance does not go
far enough to say how long the smoke will be in place.
Tuesday night through Thursday:
The next shortwave trough will begin bringing slight chances for
precipitation Tuesday night across central MT, which will
transition to northeast MT by Wednesday. Precipitation chances are
currently expected to linger Wednesday into Thursday. Any
thunderstorm will pose a risk for fire starts on Wednesday and
Thursday, as fire weather conditions are likely to be near
critical levels based on moderate to strong wind speeds, as well
as low RH values each afternoon produced by the latest NBM. A fire
weather headline may be added to the forecast in future forecast updates.
Thursday night and beyond:
The upper level ridge will regain intensity once again, which will
continue to bring above average temperatures and quiet weather.
-Stoinskers
&&
.AVIATION...
UPDATED: 2030Z
FLIGHT CONDITIONS: VFR becoming VFR/MVFR after 12Z Monday
DISCUSSION: Quiet conditions will persist through the cycle.
Another round of wildfire smoke out of Alberta is expected to
push through the area starting Monday morning. This will have the
potential to reduce visibility down to MVFR/IFR levels
WINDS: North/northwest at 10 to 20 kts becoming light and variable
after 05Z.
-thor
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Grand Rapids MI
1021 PM EDT Sun Aug 27 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1020 PM EDT Sun Aug 27 2023
High pressure remains firmly in control of the Great Lakes area
weather tonight. Dew points are generally in the low 50s across
Southwest Lower Michigan this evening, which is rather dry for
even late August. The dry air and light winds provided by the high
will allow for readings to drop to lows in the middle 40s to
around 50 degrees. As temperatures dip to the current dew points
and below we should see some shallow fog develop, especially late
when winds dip to below 6 mph in the lowest 1000 feet. All in all
a very quiet night.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 153 PM EDT Sun Aug 27 2023
- Cool temperatures again tonight
An area of high pressure over Northern Lower MI slips slowly south
through the night. Thus the winds will weaken as the pressure
gradient weakens and the mixing heights diurnally lower. Surface
dewpoints are mostly in the mid 40`s to lower 50`s. We should be
able to radiate down to those levels and once again, normally
colder locations like Leota in Clare County may fall into the
30`s. These values are about 10 degrees below normal for this time
of the year.
- Risk for showers late Monday night
The surface front will be approaching from the northwest later
Monday night. The latest HRRR, RAP and NAM show the low level
moist ridge arriving mainly after 06z Tue along with weak
instability. With water temperatures around 70 degrees, some
moisture may flux off the lake and enhance this front somewhat. We
will therefore feature a chance for showers and thunderstorms for
northwest zones which will be closer to this front. Ensemble qpf
trends suggest any qpf will be limited, especially from the GFS
showing very few members with any rain through 12z Tue. The
incoming 12z deterministic ECMWF is kinda we for northwest zones
by 12z Tue so we will need to monitor trends.
.LONG TERM...(Tuesday through Sunday)
Issued at 153 PM EDT Sun Aug 27 2023
..Showers and storms Tuesday into Wednesday...
A positively tilted trough will deepen and dig into the region Tuesday.
There is some thickness advection and a little bit of a temperature
differential as the cold front drop through mid to late Tuesday. The
models are in fair agreement on QPF remaining north of I 96 and
east of US 131 with the best chance of QPF in and around the Thumb.
The latest EC has brought some of the QPF, upwards of a quarter of
an inch, through SW MI. So we could get some scattered showers and
based on instability there could be some isolated storms associated
with it as well. We are outlooked for general thunder by SPC.
A dry and cooler air mass will move down into the region in the wake
of the exiting cold front with an approaching high. That setup
typically could cause higher winds and waves on Lake Michigan and
will be discussed further in the Marine sections.
...Cool and dry air for the rest of the week...
As stated is previous discussions, cooler and dry air will build over
the region from midweek to the end of the week. Fair and mild
weather will dominate through this timeframe. Latest ensembles do
show a surge of warm air at 850mb which will begin to advect into
the region by Saturday. This will bring Max temperatures into the
80s this weekend. However, the forecast looks to be dry through this
timeframe.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 730 PM EDT Sun Aug 27 2023
Overall, this set of forecasts is fairly uneventful, with only
some light fog possible very late tonight/early Mon morning. Skies
are starting out mostly clear, with some thin smoke in the higher
levels of the atmosphere, and a few high based cumulus clouds.
Skies should go mostly clear.
With high pressure moving overhead tonight, winds through the
lowest 5k ft should drop to less than 10 knots. This setup,
combined with a warm ground and cool air mass, brings the
potential for some shallow ground fog. We have indicated this with
MIFG at most of the sites. KLAN and KJXN have a little more
potential based on their crossover temperatures (min dew point at
max heating) and forecast lows tonight. Have gone with MVFR at
KLAN, and IFR at KJXN where the site sits in a lower spot.
Any fog will dissipate quickly on Monday morning with plenty of
sunshine and winds coming up some. Maybe few-sct mid/high clouds
late in the period.
&&
.MARINE...
Issued at 153 PM EDT Sun Aug 27 2023
It`s looking increasingly likely that hazardous swim and boating
conditions will be developing at some point Tuesday and will
likely continue into possibly Wednesday. Warm air advection ahead
of the front followed by stronger cold air advection behind it
are forecast to lead to the hazardous conditions. No headlines yet
but the HWO was updated to reflect this possibility.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Duke
SHORT TERM...MJS
LONG TERM...Ceru
AVIATION...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1040 PM EDT Sun Aug 27 2023
.UPDATE...
Issued at 1040 PM EDT SUN AUG 27 2023
Sort of a low confidence forecast for the rest of tonight. Made
some adjustments to precip chances across the area per current
radar trends, as latest model data has not been handling the
current evolution of precipitation very well. Left in slight
chance of thunder for tonight, as convection has been
occasionally flaring up, especially along the TN border. Shower
activity has expanded a bit further northwest than anticipated, so
adjusted the new forecast to account for that. Current convective
activity is waning a bit, as said earlier, things have flared up
occasionally, and considering persistent convection that
unexpectedly popped late yesterday evening in our southwestern
counties, and persisted for several hours, did not feel
comfortable taking pops down any lower or completely removing
thunder from the forecast. The updated zone forecast product has
already been issued. The updated grids have been saved, published,
and sent to NDFD and remote web farms.
UPDATE Issued at 635 PM EDT SUN AUG 27 2023
Just sent out a quick forecast update. Removed late afternoon
period the dayshift needed to put in to address ongoing
precipitation at the end of the shift. Also made a few adjustments
to this evenings precip chances per the latest radar loops. The
updated grids have been saved, published, and sent to NDFD and
remote web farms.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 439 PM EDT SUN AUG 27 2023
Key Points:
* A wavering frontal boundary and passing disturbances will lead
to chances for showers and some storms, mainly across southern
sections through the short term period.
* Rather slow storm motions with activity through this evening
could lead to locally heavy rain.
* Locally heavy rain could occur with any convection nearer to
the VA and TN borders on Mon afternoon and evening.
Late this afternoon, an upper level ridge was centered across the
southwest Conus with a general broad trough weakness extend into
the eastern Conus from an upper level low north of Hudson Bay
between the southwest Conus ridge and another ridge centered to
the east of Bermuda in the western Atlantic. A slow moving
shortwave trough was moving across the Lower OH Valley and TN
Valley regions today Another shortwave was moving across the
western Great Lakes. Further upstream a shortwave trough rotating
around the upper level low in northern Canada extended into
Ontario and Manitoba. The region was in a PW gradient north and
northwest of a wavy frontal zone extended from the Atlantic into
the Carolinas and then southwest across the Gulf coast states to
the Southern Plains. PW ranged from just over 1 inch in northern
Fleming County to around 2 inches in Wayne and McCreary Counties.
Further north, sfc high pressure was centered across the Great
Lakes and southern Ontario. The slow moving shortwave was
interacting with lingering the moisture/PW gradient and the
frontal zone to the south and southeast of eastern KY and leading
to convection from central into eastern KY and south into middle
and eastern TN. Some heavier rain fell over the past few hours
locally in Bell County, with radar estimates between 2.5 and 3
inches south of Oaks and west of Cubage. Convection in the
southern portion of the CWA has rather weak shear of 20KT at most.
The slow moving shortwave trough will progress slowly east tonight
and into tomorrow and continue to interact with the wavy frontal
zone and PW gradient. As the shortwave currently in the Great
Lakes interacts with the initial eave later tonight and into
Monday, deeper moisture should pivot northwest deeper into
southeast KY. The region should generally remain east of the axis
of troughing at 500 mb/or within a weakness to the south of a
stronger trough digging into Ontario and the Great Lakes as this
trough develops between ridging in the western Conus that builds
north into the Rockies and the ridge in Atlantic.
Mesoanalysis and RAP guidance suggests a slight increase in shear
early this evening near the TN border which may lead to somewhat
organized or help sustain convection in the south near the TN and
VA border where MLCAPE of around 500 J/kG to locally as high as
1000 J/kg is expected over the next couple of hours. MLCAPE
should diminish through the evening, though with the weak
shortwave moving slowly across the area shower chances should
continue into the night across the south and southeast as the PW
gradient will also remain in the vicinity.
A diurnal uptick in coverage of convection is probable on Monday
with the trough axis to the west and a PW gradient remains in the
vicinity. Also, a sfc response of an inverted trough west of the
Appalachians from the Cumberland Plateau of TN may develop with
this possibly being a focus for convective development along and
to the east of it. Chances should diminish a bit by late Mon
evening, but still remain with the trough axis to the west and PW
gradient remaining in the area as the inverted trough shifts a bit
to the east.
A gradient in lows from northwest to southeast is expected
tonight as far northern areas have a drier airmass in place and
could have some partial clearing. Lows in the northwest will be in
the low to mid 60s with mainly mid to upper 60s in the south.
Highs Mon should be a couple of degrees below normal, near 80 to
the lower 80s. A similar northwest to southeast gradient in lows
is anticipated on Mon night with lower 60s north and northwest
and mid to upper 60s in the south.
.LONG TERM...(Tuesday through Sunday)
Issued at 334 PM EDT SUN AUG 27 2023
Key Points:
* Temperatures more typical of late summer continue through the
last days of August and the first days of September
* A wavering frontal boundary will lead to area-wide rain chances
on Tuesday.
* Dry high pressure tries to build in for the remainder of the
week -- probability for direct impacts from Tropical Storm
Idalia appears to be diminishing.
The 27/12z model suite 500H analysis beginning Tuesday morning shows
troughing extending southward from an ~517 dam low over Baffin
Island to across the Lower Ohio and Tennessee valleys. A couple
of tropical systems, Franklin and Idalia, will be spinning
southwest of Bermuda and northwest of Cuba, respectively. At the
surface, a wavering frontal boundary will still be draped along
the western foothills of the Appalachians.
Through the day on Tuesday, one or more waves of low pressure are
expected to ride along the boundary bringing rounds of showers and
possible thunderstorms to eastern Kentucky. The highest rain chances
are near the Virginia border. That front is now projected to settle
southeastward mid-week as models have come into better agreement
with the track of Idalia mid-week. The system appears likely to
track across north Florida and southeast Georgia before being
captured by the longwave 500H trough and be carried off the coast
of the Carolinas. This outcome would keep any notable impacts
well southeast of the Coalfields. There could still be a little
bit of a northeasterly breeze though on Wednesday and Thursday,
thanks to a moderately strong pressure gradient between Idalia and
surface high pressure building into the Great Lakes. As Idalia
departs, high pressure will build southward along the Appalachians
for the remainder of the week. Temperatures are expected to reach
the upper 70s to lower 80s through Thursday before warming into
the middle 80s to round out the week. Nighttime lows should range
from the mid 50s to lower 60s initially but generally moderate
into the lower to middle 60s for most locations by the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 728 PM EDT SUN AUG 27 2023
The TAF forecast for tonight will be challenging at times, with
widespread low, mid, and high level cloud cover streaming across
the area. Scattered showers will also persist around the area, and
could affect LOZ, SME, and JKL at times this evening, bringing
MVFR conditions. These showers should continue to slowly dissipate
overnight, but we should see at least isolated showers lasting
through late tonight. With so much moisture and light winds in
place, areas of fog are likely. The fog will be most widespread
and densest near bodies of water, in deep sheltered valleys, and
for locations that have received or will receive rainfall during
the period. All of the TAF sites could see fog, but JKL, LOZ, SME,
and SJS are mostly likely to see fog due to moist conditions due
to precipitation and light winds. JKL may experience breif periods
of IFR or LIFR conditions tonight due to fog and low clouds. LOZ,
SME, and SJS may see MVFR to IFR conditions at times due to fog
and low clouds. The fog should finally lift and dissipate by 13 to
14Z on Monday, with SCT to BKN clouds persisting through out the
day. Scattered to numerous showers, and scattered storms, will be
possible on Monday, especially late in the day and along the VA
and TN borders, as a sluggish storm system moves by to our south
and southeast on Monday. LOZ, JKL, and SJS would have the best
chances of seeing showers and storms on Monday due to the current
forecast track of a southern stream storm system. MVFR conditions
will be most likely with any rain, but could be worse if a given
airport experiences a thunderstorm or intense showers.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AR
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...AR
Area Forecast Discussion
National Weather Service Pendleton OR
813 PM PDT Sun Aug 27 2023
.EVENING UPDATE...Main concerns for this evening were to address
the smoke flowing across the Cascades into Central through North-
Central Oregon. Visibilities have dropped in the Bend/Redmond
area to less than or around 3 miles, so have added smoke into the
grids here as well as utilized the HRRR smoke model to address the
flow of it through tomorrow. With precipitation gone, have also
removed precipitation for the next few hours. Finally, winds a bit
breezier at The Dalles, so have brought in a bit more wind to
this region for the overnight hours. Outside of this, no major
changes necessary and the forecast remains on track from this
afternoon as we expect the incoming pattern change followed by a
chance at more showers and thunderstorms across the CWA to begin
the week. Goatley/87
&&
.PREV DISCUSSION... /issued 428 PM PDT Sun Aug 27 2023/
AVIATION...00Z TAFs...VFR conditions expected all sites next 24
hours. Breezy at DLS this evening and overnight with gusts between
15-20kt gusts, otherwise lighter winds elsewhere at generally
diurnal direction to even light and variable. Mostly clear to
FEW/BKN high elevation clouds expected. Any showers or storms seen
on radar currently should remain away from aviation sites.
Goatley/87
PREV DISCUSSION... /issued 247 PM PDT Sun Aug 27 2023/
SHORT TERM...Tonight through Tuesday...Radar and satellite
imagery show isolated thunderstorms have begun to develop along
the higher peaks of the northeast OR mountains this afternoon,
while the remainder of the forecast area remains seasonably hot
and dry.
Thunderstorms will continue to initiate off the higher peaks and
ridges across the eastern mountains through this evening, as
southerly flow aloft and daytime heating aid their development.
Meanwhile, the rest of the forecast area will continue to remain
dry while temperatures continue to warm into the 90s across the
lower elevations, and mid 70s to 80s in the mountains.
Tomorrow through Tuesday, the region will undergo a pattern change
aloft as an upper low currently offshore the PacNW approaches the
region as it becomes a negatively tilted trough and pushes an
upper ridge (currently over the region) to the east. Impacts from
the upper low will start Monday afternoon as isolated
thunderstorms begin to develop across central OR and the east
slopes of the Cascades. Thunderstorm development will initially be
driven by increasing instability from daytime heating across
central OR and the eastern mountains Monday, but will then spread
north and east late Monday through Tuesday morning as the upper
trough and elevated instability pushes across the PacNW. PWATs
will be increasing to between 0.8 to 1.1 inches from northern
Deschutes county to central WA Cascades and western Columbia Basin
Monday, with isolated to scattered thunderstorms producing heavy
downpours with frequent lightning possible mainly along the east
slopes of the Cascades. However, there is a slight chance (15-20%)
across central OR and the eastern mountains for drier isolated
storms to develop through Monday evening, but confidence in these
storms developing is low-moderate (35%) at this time.
Shower chances will increase across the northern 2/3rds of the
forecast area overnight Monday into Tuesday as the upper trough
axis pushes west across the PacNW. Some elevated instability in
the form of mid-level lapse rates around 7-9C/km and 0-6km shear
from 35-45kts will sustain isolated to scattered thunderstorm
chances Monday night through Tuesday morning, while the passage of
the trough axis aloft and a surface cold front will help to
produce at least isolated thunderstorm chances across the eastern
mountains and the Columbia Basin through the remainder of Tuesday.
By Tuesday night, shower and thunderstorm chances will diminish
from southwest to northeast across the region, while rain showers
continue across the WA and northern OR Cascades. Westerly winds
will be on the increase across the region starting late Monday as
the trough approaches, and will peak by Tuesday afternoon with the
passage of the trough axis and a cold front at the surface. In
the Kittitas valley, eastern Columbia River Gorge, and the OR
Columbia Basin, sustained winds of 30 to 40 mph will be possible
with wind gusts between 45 to 55mph. In these areas, probabilities
of wind gusts meeting or exceeding 50mph are between 60-80%,
while the probability of exceeding sustained winds of 35mph is
between 55-75%. Elsewhere in the lower elevations, sustained winds
of 20-30 mph are possible with winds gusts generally 35-45mph.
Seasonably hot temperatures of mid to upper 90s in the Columbia
Basin, and lower to mid 90s in the remainder of the lower
elevation zones can be expected Monday afternoon. With the
trough/frontal passage Monday into Tuesday, afternoon temperatures
will decrease down into the mid 70s to lower 80s in the lower
elevations.
LONG TERM...Wednesday through Sunday...The extended period is
characterized by a dropping upper level low pressure system that
stalls off the Oregon/northern California coasts through much of the
period before ejecting to our east into the early part of the
workweek. This will keep temperatures slightly below normal until
the weekend, as above normal temperatures return and extend into the
early part of the week. Afternoon shower and thunderstorm chances
also persist after Thursday and continue through the weekend. The
other concern through the long-term is associated with breezy
conditions Wednesday morning and afternoon across the Lower Columbia
Basin and Eastern Gorge as gusts of up to 37 mph will be possible
out of the west-southwest.
The upper level trough that passed through the Pacific Northwest
earlier in the week will continue to push east and into Central
Montana Wednesday morning as an upper level ridge across the Pacific
begins to strengthen and extend into the Gulf of Alaska. Pressure
gradients will still be rather tight in the wake of the departing
trough to allow for breezy conditions across the Lower Columbia
Basin and Eastern Gorge through the morning and afternoon hours on
Wednesday. An upper level trough will begin to dig along the Pacific
coast Wednesday afternoon, which will be reinforced by a shortwave
dropping along the British Columbia coast. This will culminate into
the development of an upper level low pressure located off the
Washington/Oregon coasts Thursday afternoon, providing chances (25-
35%) for early morning showers and isolated thunderstorms primarily
along the east slopes of the Cascades and Central Oregon. These rain
and storm chances look to linger into Friday and extend slightly
eastward to incorporate the Yakima Valley, John-Day/Ochoco
Highlands/Basin, and the Blue Mountains/foothills. The upper low
continues to camp off of the Oregon coast into Saturday, keeping
southwest flow aloft and temperatures warming as highs break into
the mid to upper 80s across the Lower Columbia Basin, Eastern Gorge,
Central Oregon, and the Yakima/Kittitas Valleys - which is currently
the warmest day forecast in the extended period. The offshore low
will also keep a slight chance (15-20%) of developing afternoon
showers and thunderstorms on Saturday across the east slopes and
through the Southern Blue Mountains, with chances extending into the
eastern and Northern Blue Mountains on Sunday as the upper low looks
to finally begin to push onshore over the Northern California coast.
Guidance is in good agreement with the overall pattern of a dropping
upper level trough that stalls as an offshore upper level low
pressure off the Washington/Oregon/Northern California coasts
through the majority of the period, but differences in this system`s
location and strength arise. The ECMWF keeps the low weaker and
further offshore than the GFS, which relates to a drier, cooler, and
less windy outcome with the ECMWF. Current ensemble clusters
highlight greater confidence in the GFS scenario, as more ensemble
members are aligned with each other and the deterministic outcome.
Thus, the NBM was utilized through the extended period to provide an
applicably weighted scenario, with a slight lean toward the GFS
outcome of a slightly wetter, cooler, and windier end of the week.75
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 63 95 61 75 / 0 10 20 40
ALW 66 98 64 78 / 0 10 20 50
PSC 67 99 66 82 / 0 10 30 60
YKM 64 95 62 81 / 0 10 50 60
HRI 64 98 64 79 / 0 10 20 40
ELN 63 95 60 74 / 0 10 60 70
RDM 56 90 54 74 / 20 10 20 10
LGD 60 93 58 76 / 20 10 20 40
GCD 59 96 56 76 / 20 10 20 20
DLS 67 91 64 77 / 10 20 40 40
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
EVENING UPDATE...87
SHORT TERM...82
LONG TERM....75
AVIATION...87
Area Forecast Discussion
National Weather Service Pueblo CO
324 PM MDT Sun Aug 27 2023
.SHORT TERM...(This evening through Monday)
Issued at 246 PM MDT Sun Aug 27 2023
1) Scattered showers and thunderstorms are expected through the
evening with highest probabilities over the eastern mountains and
along the I-25 corridor. Some stronger storms may produce flash
flooding.
2) Showers and possibly a storm or two will likely continue through
tomorrow morning for some areas. There could be some areas of patchy
fog developing in the San Luis Valley late tonight and through the
early morning hours tomorrow.
3) More developing showers and thunderstorms are expected tomorrow.
Most of the showers and storms will again be over the eastern
mountains and along the I-25 corridor. There will still be a risk
for some flash flooding with some of the stronger storms, especially
for the burn scar areas.
4) It will still be on the cooler side tomorrow, especially for the
plains, with temperatures as much as 10 degrees below the seasonal
average for some locations.
Detailed discussion:
Tonight...
Latest radar imagery shows storms beginning to develop just north of
Canon City, which aligns better with what the HRRR was showing in
the previous model run. There are also a few storms located over the
Sangres and up around Monarch Pass, over the La Garitas, and moving
over the upper Arkansas River Valley. These storms are expected to
impact portions of the San Luis Valley in time once the move off of
the mountains. There are also some storms that are located near the
Spring burn scar at the moment (most of the heaviest precip is right
along the eastern edge) which could cause problems if they back
build towards the west.
The latest HRRR model run continues to show the evolution of a
possible MCS over the Wet Mountains around 6 PM and then moving
southeastward with re-development over the Raton Mesa area by around
8 PM. It also has more development over the Palmer Divide area as
well than other CAMs. It should be fair to say that it has been
overdoing convective initiation and progression in recent days and
the NAMNest has actually been a little better at resolving where
convection has been in comparison. A consensus of the CAMs show that
the majority of the showers and thunderstorms will be located over
the eastern mountains and along the I-25 corridor, with the areas of
highest QPF being over the Wet Mountains and along portions of the I-
25 corridor through the overnight hours. The better instability,
with some CAPE of nearly 2000 J/kg will be over Las Animas County,
where there could be some stronger storms than may produce severe
criteria winds and possibly hail up to an inch in diameter.
Effective bulk shear is weak, and therefore a few of the storms
could remain nearly stationary at times, and also cause flash
flooding issues for other locations as well over the higher terrain.
Heavier showers and storms over the southern Sangre de Cristo
Mountains could also impact the Spring burn scar area if they become
stalled over this area again later this evening. Storms should
generally move towards the southeast with northwest flow aloft.
Models also indicate that there will be an abundance of moisture and
likely showers with a few storms continuing into the overnight hours
for some locations, mainly over the plains. There is a lot more
stable conditions the further east you go to the Kansas border and
therefore a lesser chance of storms holding together in strength as
they move towards these areas. That being said, there is still the
possibility of showers moving over this area through the early
morning hours tomorrow.
Mostly cloudy skies over the higher terrain will partially clear
going into the early morning hours. There could be some low clouds
and patchy fog developing in the San Luis Valley later tonight and
during the early morning hours, especially if they receive any
precip later on this evening. Lows tonight will drop down into the
upper 50s to low 60s for most of the plains. For high country, lows
will generally be in the 40s to low 50s.
Tomorrow...
With the upper level disturbance still moving overhead, along with
an ample amount of moisture in the mid to upper levels over the
region, there will be storms regenerating throughout the day again
tomorrow with almost an exact repeat of thunderstorm coverage as
there was today. CAMs display the best convection for tomorrow being
almost exactly in the same locations, perhaps only a slight shift
further east for better QPF values. Most areas will still have a
chance of receiving some measurable precip, whether it is from a
storm or just a shower. The best MUCAPE by tomorrow afternoon once
the lower levels destabilize from daytime heating will be along and
east of the I-25 corridor. There could be some bigger storms further
east as well tomorrow, with some of the guidance showing a possible
LEWP (line echo wave pattern) formation along the I-25 corridor that
will eventually push eastward and encompass the entire far eastern
plains. There will be the chance for a few of the heavier storms to
cause flash flooding issues again tomorrow, mainly over the burn
scar areas, but perhaps for urbanize locations along the I-25
corridor and the US-50 by later in the afternoon. Mostly cloudy
skies and cooler temperatures will remain in place tomorrow as well,
with highs still averaging nearly 10 degrees below the seasonal
average for locations over the plains. Max temps will get up into
the upper 70s to mid 80s for the plains, and generally in the 70s
for the high mountain valleys, with 50s and 60s for the higher
elevations, and even a few mid to upper 40s for the tallest peaks.
-Stewey
.LONG TERM...(Monday night through Sunday)
Issued at 246 PM MDT Sun Aug 27 2023
Key Messages:
1) General trend toward warmer and drier weather begins Tuesday,
continuing through the end of the week.
2) Renewed push of monsoon moisture late week into next weekend
may bring back better thunderstorm coverage to the mountains,
especially near the Continental Divide.
Models suggest lingering convection Monday night may be slow to
dissipate, and will keep relatively high pops in place through
midnight, plus hold on to at least some scattered showers through
Tue morning. Upper ridge then builds Tue with deep trough over
the Pacific Northwest. Building heights and low/mid level drying
suggest once lingering Tue morning convection ends, afternoon
storm coverage may be fairly sparse, with best chances over the
srn mts near the NM border. Blended model guidance pops looked
rather high Tue afternoon and toned them down somewhat, but
suspect we`ll need to go even lower in subsequent forecasts. Do
expect one last cooler than average day Tue, as max temps remain
in the 70s/80s at most locations.
Center of upper level high pressure re-forms somewhere near the
4-corners on Wed, drifts eastward through the srn Rockies Thu,
then ends up over the srn High Plains on Fri. Proximity to the
upper high and general wly downslope flow across srn CO argue for
hot and dry conditions, though just enough recycled moisture will
be available some isolated/weak afternoon convection, limited
mainly to the mountains. Max temps Wed and Thu bounce back to
above average levels, and 80s/90s will be widespread across the
area. As ridge slips east from Fri into the weekend, renewed
monsoon plume of moistures over the desert southwest moves
northeast, bringing increased thunderstorm chances to the
mountains, especially along the Continental Divide, while eastern
plains look to stay dry and hot, and a few spots over the lower
Arkansas Valley will approach 100f each afternoon from Fri
through Sun.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 246 PM MDT Sun Aug 27 2023
VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. SHRA and TSRA are
expected to be in and around the vicinity of all stations through
the evening hours, with a better chance of occurrence at KCOS and
KPUB. If SHRA/TSRA does develop, it could temporarily reduce CIGs
and VIS to MVFR/IFR criteria. It could also result in periodic
windshifts and increased wind speeds at either of the terminals.
There could also be SHRA/VCTS near the end of the forecast period
for KCOS and KPUB by around 21Z, although a lesser chance for KALS
tomorrow. There could be some low CIGs developing, and possibly
reduced VIS in BR/FG at KALS during the morning hours between 10 and
16Z, although at this time there is not enough confidence to put
CIGs and VIS below 5SM in the TAF for KALS. Winds will be mainly
diurnally influenced at all terminals and generally light (below 10
kts).
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...STEWARD
LONG TERM...PETERSEN
AVIATION...STEWARD
Area Forecast Discussion
National Weather Service Blacksburg VA
955 PM EDT Sun Aug 27 2023
.SYNOPSIS...
Rounds of heavy rain and thunderstorms continue into the
beginning of the work week as a stalled front remains over the
Carolinas. A stronger cold front will arrive next week,
bringing cooler temperatures and drier conditions to the region.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 950 PM EDT Sunday...
Precipitation coverage across the region is transitioning fairly
close to our earlier expectations. Central regions of the
forecast that have been dry most of the night so far are
starting to see some of their first drops. This would include
areas such as Blacksburg, VA to Roanoke, VA and Stuart, VA to
Roanoke, VA. Additionally, showers and storms near and northeast
of Danville, VA are moving slow progression westward with bit
more coverage and intensity in the activity. Coverage is
expected to continue to increase across central portions of the
area into the early morning hours of Monday. As we approach
daybreak Monday, the trend will be for the greatest coverage to
progress more east or northeast through the area.
As of 650 PM EDT Sunday...
Showers and storms have been abundant across portions of
Southwest Virginia and Northwest North Carolina. As the night
progresses, a shortwave trough current across the Lower Ohio
Valley is expected to head eastward and then northeastward. Its
progression will also influence the expected trends of showers
and a few storms over night. Anticipate a general trend in the
coverage of the precipitation into central sections of the
region by the late evening or middle of the night, and then
focused more on central to northern sections by daybreak Monday.
This is not to say other area will be dry, simply the best focus
for best coverage will follow this expected trend. Patchy fog is
still expected overnight, especially along the river valleys and
where rainfall today/tonight was/will be the heaviest.
Have tweaked hourly temperatures, dew points, wind speed/gusts,
and sky cover to better reflect the latest observations and
expected trends through the evening hours.
As of 130 PM EDT Sunday...
Key Messages:
1. Slight Risk of severe weather and flash flooding in northern
NC/Southside VA this afternoon through tonight.
2. Localized flooding due to slow moving, repeated high rainfall
rate storms possible.
3. Potential resurgence of storms in NC High Country and
southern Blue Ridge.
Low-level stratus is now beginning to lessen over the area this
afternoon, allowing for ample heating. As such, instability will
be on the rise, thus creating an environment conducive for
cluster of thunderstorms. Overall, not much upper support for
organized storms as the best forcing has moved south with the
front that is now draped across the Carolinas. The main threat
will be slow moving and training storms with very efficient
rainfall rates.
RAP mesoanalysis and the morning RNK RAOB indicate plenty of
ambient moisture along with high freezing levels for efficient
warm rain processes to occur. This has been seen already this
morning across Appomattox and Charlotte Counties, as well as
ongoing renewed convection over NW NC, where rain rates within
storms could be 2-3"/hr at times. It is not out of the question
for some locations to pick up 2-3" (locally higher) of rainfall
in a very short amount of time. Although antecedent conditions
are rather dry, prolonged high rainfall rates over the same area
will cause flooding issues regardless of how dry current
conditions are.
Should see coverage lessen a bit overnight, but could still see
areas of heavy downpours continue. Likely to have low clouds and
some fog development tonight with plenty of low-level moisture
present.
This pattern is expected to continue into Monday with the
potential for localized flooding concerns from very slow moving
thunderstorms that are expected to develop again in the
afternoon/evening.
While humid, temperatures will be held to the upper 70s and low
80s due to cloud cover and rain. Very mild and humid overnight
in the 60s and low 70s.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 115 PM EDT Sunday...
Key Messages:
1. Locally heavy rainfall possible, particularly over
northwest North Carolina, through the period.
2. Temperatures near to cooler than normal.
A front is expected to stall across the Carolinas and southeastern
states through this forecast period. While the front remains just to
the southeast of the area, it will serve as a source of lift for the
development of showers and thunderstorms through early Tuesday.
Precipitable water values are forecast to be around 1.5 to 2 inches,
which is anomalously high for this time of year. The greatest
potential for repeated rounds of showers and thunderstorms is
mainly along and south of the VA/NC border, closer to the front,
where there is modest CAPE as well. The high moisture in the
atmosphere could lead to very efficient rainfall rates in that
area. Thus, there is a Slight Risk for excessive rainfall over
portions of northwest and North Carolina, leading to possible
flash flooding.
Abundant cloud cover over the area will hold temperatures down to a
few degrees below normal, with highs in the 70s and lows in the low
to mid 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 135 PM EDT Sunday...
Key Messages:
1. Track of Tropical Storm Idalia continues to be
monitored, currently forecast to move east of the forecast area.
2. Too early to determine specific threats and impacts. Potential
impacts include gusty winds and heavy rainfall that may lead to
localized flooding.
The general mid level pattern during this forecast period is broad
ridging over the southern Plains and Central US, and troughing
developing over the northeast and into the Mid Atlantic. The
evolution of this pattern will influence the track of Tropical Storm
Idalia, and thus, its impacts to the central Appalachians.
There is better agreement among the long range guidance on the
timing forecast, but greater spread/less agreement in the track
forecast. At this time, it is forecast to turn eastward as it
reaches the inland southeastern US, which would limit the higher
winds and heavier rainfall to the North Carolina Piedmont and
Virginia Southside. The earliest reasonable timing for any
impacts to the forecast area looks to be as early as late
Wednesday, but most likely early Thursday morning. However, it
is important to remember that even slight changes in the track
can bring big changes to the potential threats and impacts, so
please continue to monitor the current forecast for the latest
information.
By Friday, surface high pressure will build into the area from the
Great Lakes, which will help to push both the stalled front and the
Tropical Storm farther from the area. Subsidence, and dry
northwesterly flow from the high will bring about clearer skies and
will limit precipitation chances through the remainder of the long
term forecast period.
Expecting temperatures to be on a slow warming trend through the end
of the work week and into the weekend, getting back into the upper
70s to mid/upper 80s.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 740 PM EDT Sunday...
Overnight, cigs will lower and fog is likely to develop across
most of the area. Widespread sub-VFR looks likely until sunrise
on Monday. Even then, still will have some low stratus
continuing that could keep conditions in the IFR to MVFR through
mid-morning.
Showers and thunderstorms will trend more numerous across the
region during the afternoon and early evening hours. Conditions
may be temporarily sub-VFR under the strongest showers and
storms.
EXTENDED AVIATION OUTLOOK...
Weather pattern remains unchanged through Tuesday with
additional chances for showers and thunderstorms and the
associated MVFR conditions, though VFR expected most of the
time. Isolated to scattered showers and thunderstorms are
possible on Wednesday with best chances in the south. For
Thursday and Friday, will need to watch what happens with
tropical depression 10.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...BMG
NEAR TERM...BMG/DS
SHORT TERM...AS
LONG TERM...AS
AVIATION...BMG/DS
Area Forecast Discussion
National Weather Service Shreveport LA
1012 PM CDT Sun Aug 27 2023
...New UPDATE...
.UPDATE...
Issued at 1007 PM CDT Sun Aug 27 2023
Pleasant rainfall across the southern half of our region this
evening but with the rain, we have been dealing with strong,
downburst winds which has downed some trees and powerlines across
portions of our region as well. Unfortunately, the cloud to ground
lightning strikes have been causing some additional fires as well.
For the evening update, raised pops to likely category through 3am
given the storm coverage currently across our region, backing pops
back to low end chance category across mainly Deep East Texas into
Northern Louisiana. Big spreads with overnight low temperatures
tonight as those areas having received rainfall are very close to
their forecast lows while areas without rain are quite a bit
above. Did massage low temperatures in a few locations based on
rainfall but otherwise...not may changes large changes with
temperatures.
Updated forecast package has already been sent...13.
&&
.SHORT TERM...
(This evening through Monday Night)
Issued at 244 PM CDT Sun Aug 27 2023
Radar imagery from this afternoon is starting to show some
thunderstorms developing across east Texas and central Louisiana
south of the I-20 corridor. Expecting this activity to continue to
increase this afternoon. There is a potential that a few of the
storms that develop could become strong with gusty winds possible
at times. As we move into the overnight hours, a weak shortwave
will move through the region that will bring another shot for
showers and thunderstorms across portions of the area.
Temperatures tonight will range from the upper 60s across our far
northern zones while the remainder of the area will range from the
lower to mid 70s.
Here is something we have not been able to say for a while,
seasonable temperatures are expected for Monday, with afternoon
highs ranging from the upper 80s to mid 90s across the area. Heat
index values should remain below 105 degrees for the entire
region, with the only area getting somewhat close to this number
is portions of deep east Texas. There was not enough confidence
for me to want to put out any heat related headlines for Monday,
but that is not to say a few areas will not occasionally hit 105
degrees across deep east Texas. There will also be a chance for
isolated showers and thunderstorms across portions of the area on
Monday, however, the best chances appear to be for our far
southern zones. Low temperatures Monday night will range from the
mid 60s across our northern zones to the mid 70s across our
southern zones. /33/
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 244 PM CDT Sun Aug 27 2023
Northerly/northeasterly flow aloft is expected over the area at the
start of the long-term period. The axis of the semi-permanent ridge
that we`ve been dealing with will extend from the Four Corners ridge
into the Central/Northern Plains, while an upper trough will dig
over New England. Meanwhile, Idalia will be in Northeast Gulf of
Mexico, approaching Florida. A weak upper trough draped from
Southern Tennessee into Southern Louisiana may help to provide some
ascent for isolated diurnally-driven showers and thunderstorms on
Tuesday afternoon southeast of a line from Lower Toledo Bend to
Monroe. After the convection dissipates early Tuesday evening, the
forecast will be precip-free until Friday.
On Thursday, a weak cutoff low will develop off the coast of Texas.
As the low strengthens, deep onshore flow will return to the area,
which may help to enhance diurnally-driven sea breeze convection
during the afternoon Friday and Saturday. However, coverage will
remain isolated at best and will be confined to areas southeast of a
line from Lower Toledo Bend to Columbia LA.
Unfortunately, the bigger story will be the return of critical fire
weather conditions. As the rain chances come to an end, relative
humidity levels will begin to fall again. Afternoon minimum RH
values will likely fall below 30 percent across much of Louisiana
and East Texas from Tuesday through Saturday. The greatest concern
will be Tuesday and Wednesday when the low RH values will also
coincide with sustained wind speeds between 10 and 15 kts. While
most locations should remain below 100 degrees F through Thursday,
the heat will gradually build and triple digit daytime highs should
return to portions of the area by Friday and Saturday. While Heat
Advisories may be necessary by next weekend, we should still be far
from the oppressively hot conditions we`ve experienced lately.
CN
&&
.AVIATION...
(00Z TAFS)
Issued at 600 PM CDT Sun Aug 27 2023
Scattered convection currently ongoing across our southern
airspace south of the I-20 Corridor and near the I-30 Corridor of
NE TX and SW AR. For the 00z TAF package, have prevailed VCTS at
the TXK and LFK terminals only, with VCTS a little later in the
evening for all terminal locations with the exception of the ELD
terminal. If latest HRRR and CAMS are correct, convection should
be winding down across our airspace in the 08-12z timeframe and
have trended 00z terminals in that way. Model time-height cross
sections are supporting the possibility of MVFR ceilings overnight
across most terminals but will wait on one more model run before
inserting these ceilings restrictions overnight through mid
morning on Monday. Look for mostly north to northeast winds near 5
to 10kts overnight except with stronger gusts in the vicinity of
thunderstorms.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 75 91 74 93 / 60 40 10 10
MLU 74 92 72 93 / 60 40 20 20
DEQ 70 89 67 92 / 20 10 0 0
TXK 72 89 69 92 / 20 20 0 0
ELD 70 86 68 87 / 20 30 10 10
TYR 76 94 74 96 / 60 20 10 0
GGG 74 92 72 95 / 60 40 10 10
LFK 76 96 75 98 / 60 40 20 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...33
LONG TERM....09
AVIATION...13
Area Forecast Discussion
National Weather Service San Angelo TX
654 PM CDT Sun Aug 27 2023
...New AVIATION...
.SHORT TERM...
(This evening through Monday)
Issued at 215 PM CDT Sun Aug 27 2023
Convective temperature has been reached across the southern half
of the area and scattered thunderstorms have blossomed as readings
approach or exceed the 100 degree mark. Cold front also making
progress into the area and bringing a little better convergence
along with gusty north winds. Thus, scattered storms likely to
continue this afternoon and into the early evening hours,
especially south of a San Angelo to Brownwood line.
CAMs have consistently shown another convective complex moving
south or southeast out of West Texas late tonight, with the HRRR
farther east with it and pushing it into the Concho Valley by
sunrise. Namnest is a little farther west, but has the complex as
well. Will boost POPs across the central and western Concho
Valley for early Monday shortly after sunrise to account for this.
Finally, with more clouds and cooler temps behind the front, will
not need to have heat headlines for Monday. Highs forecasted to
remain in the 90s.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 143 PM CDT Sun Aug 27 2023
Our rain chances will decrease throughout the day Tuesday as the
north/northeast winds behind the front continue to bring drier air
into Texas. We could see some isolated showers in our western and
southwestern counties early on Tuesday, but most of the activity
should stay off to the west. We`ll be caught between a high pressure
to our west and a low making landfall to our east for the first half
of next week. This along with the northeasterly winds hanging out
after the frontal passage, should keep our temperatures in the 90s
through Wednesday. Our winds will then shift back south, bringing in
warmer air. To add to that, the upper high will start to push back
towards north Texas Thursday into Friday, which will help raise our
temperatures back into the 100s. Rain chances in the long term don`t
look great. The one thing to keep an eye on would be a possible
upper level disturbance moving near our area Saturday evening/night,
but right now models disagree on its strength and whether we`ll see
rain.
&&
.AVIATION...
(00Z TAFS)
Issued at 643 PM CDT Sun Aug 27 2023
Scattered rain showers will continue for another hour or two
across the I-10 corridor (KJCT and KSOA). Look for gusty
conditions and sharp wind shifts. Another round of rain showers
and thunderstorms are possible Monday morning. Uncertainty remains
in how widespread this activity will be.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 74 95 67 94 / 20 20 10 0
San Angelo 74 94 70 95 / 40 40 20 10
Junction 73 97 70 97 / 40 50 20 10
Brownwood 74 96 68 96 / 20 10 10 0
Sweetwater 73 92 68 94 / 40 40 10 10
Ozona 74 93 71 94 / 40 50 30 10
Brady 74 95 69 94 / 40 30 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM CDT this evening for Kimble-Mason-San
Saba.
&&
$$
SHORT TERM...07
LONG TERM....AP
AVIATION...41