Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/22/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
910 PM CDT Sun May 21 2023
.UPDATE...
Issued at 909 PM CDT Sun May 21 2023
Current forecast is on track, therefore no changes made at this
time.
&&
.SHORT TERM...(This Evening through Monday Night)
Issued at 220 PM CDT Sun May 21 2023
Main concern is the ongoing smoke overhead from the Canadian
wildfires which will continue through the short term. The main
challenge is how it affects our overall temperatures, especially
highs on Monday. Today, the smoke really did not impact temperatures
and has stayed more aloft (as forecasted). Temps got to 81 degrees
here at the office around 1 PM. 79 degrees was reported at Pierre,
and 81 at Mobridge around 2 PM to give a few examples. Geocolor
satellite imagery showed the shortwave over the central CWA earlier
this morning with the smoke wrapped around the vort and behind it,
as winds aloft are out of the northwest. Ensembles plus short term
models continue to show this shortwave/surface trough pushing
southeast with the center of the vort over the southern/southeastern
part of our CWA by 00Z Monday. At the same time, the ridging pattern
continues with most of the Rockies` area under the crest of the
ridge. By tonight through Monday, this ridge will push more east
with most of the CWA under the crest of the ridge, resulting in even
warmer air at 850mb. Our next mid/surface low will start to inch
closer to the CWA, from the northwest, through the day on Tuesday.
Through the afternoon, dewpoint values across the area have ranged
in the 40s into the mid 50s across the CWA. With this slight
moisture and lift from the surface trough/shortwave, CAMS/HREF hint
at maybe some isolated precip over Clark/Codington/Hamlin/Deuel
counties with most of the precip to our south in Sioux Falls WFO
area. SB/MU Cape per HREF will be at or below 1000 J/kg in this area
so not much in the way of organized thunderstorms as most of the
better shear is to our south. HREF paintball does show some cells>40
dbz in this same area. Because of this, I did add in just a slight
chance of pops here late this afternoon and evening, even though RH
values at the surface remain low. We cannot rule out rumbles of
thunder as dbz>40 with MUCAPE>50 ranges from 10-30% probability in
this same area per HREF. HREF continues to hint at some possible
pops once again for Monday afternoon along a weak surface boundary
(weaker than the one this evening). CAPE values will be at or below
1000 J/kg once again. Several soundings continue to show dry air at
the surface but I went ahead and added in chance of sprinkles to
show for these chances, although fairly low amount of confidence.
HREF/RAP indicates 500mb winds will be out of the north/northwest
tonight through at least early Tuesday morning. Right now, the smoke
is aloft over the CWA as Rap vertically integrated smoke model shows
the plume with values over 100mg/m2 and continuing over the area
through at least Monday. This is creating and will continue to
create that milky/hazy look. Rap near surface smoke model shows most
of the concern to our west/northwest over western South Dakota into
ND/MT. For example, in Dickinson ND, visibility was as low as 4 SM
at 10AM earlier today. However, near surface smoke values do creep
up a bit this evening then decrease overnight and increase again
Monday. This may result in a continued decrease in air quality and
slight viz reduction.( Currently the eastern side of the state and
Mobridge area are in yellow aka moderate index, as of 2:15 PM). With
the smoke concern, per the previous shift, I left the smoke mention
in the grids across central and western CWA through the short term.
This may need to be extended eastward as the trough moves southeast.
Sky cover remains at 30-40% as well.
850mb temps overnight will range from ~14C to 17C across the CWA
with values at Tuesday 00Z up to 16-20C. However, as mentioned, the
smoke may knock off a few degrees for highs on Monday. Overnight
lows will range in the 50s with highs on Monday ranging from the
upper 70s over the Coteau to the mid 80s.
.LONG TERM...(Tuesday through Sunday)
Issued at 220 PM CDT Sun May 21 2023
A blocky mid level pattern is expected to persist over the CONUS
through much of the period, with upper trofs over the eastern and
western CONUS, and a ridge in between. Upper ridge ring of fire
convection can`t be ruled out entirely during the period, but the
better chances for measurable rain will come toward the end of the
week. At that time, energy lifting out of the western continent will
help nudge the ridge to the east, and allow for better LL
moisture/instability to develop over the forecast area. However,
severe chances still don`t look great given relatively light winds
aloft, and therefore minimal deep layer shear. Generally speaking,
with ridging aloft over the region sfc temperatures will favor above
normal for most of the long term.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 624 PM CDT Sun May 21 2023
Terminals KABR,KATY,KPIR,KMBG
VFR conditions will prevail across the area tonight and through
the day Monday. Southerly winds may gust in excess of 20 knots
Monday afternoon. Elevated wildfire smoke from Canada will remain
over the region through the TAF period.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Parkin
SHORT TERM...MMM
LONG TERM...TDK
AVIATION...Parkin
Area Forecast Discussion
National Weather Service La Crosse WI
955 PM CDT Sun May 21 2023
.DISCUSSION...(This evening through Sunday)
Issued at 204 PM CDT Sun May 21 2023
Key Messages:
- Smoke moving into the area tonight and remaining across the
area into Tuesday.
- Small chance of showers from Tuesday night into Wednesday.
- Additional shower and storm chances for the Memorial Day
Weekend.
From Tonight into Tuesday
The RAP continues to show that the western Canadian wildfires will
gradually move south across the area through Monday and then
linger across the area into Tuesday. High temperatures will be in
the mid to upper 70s on Monday and then range from the mid-70s to
lower 80s on Tuesday. The winds will be southerly at 5 to 10 mph.
From Tuesday night into Wednesday
The deterministic models are in good agreement that a 500 mb
trough will move southeast through the Great Lakes. As this
occurs, a Canadian cold front will move south into the region.
With only weak convergence and surface dew points around 50
degrees, surface-based CAPES remain generally less than 100 J/kg,
so only expecting isolated to scattered showers along this front.
High temperatures on Wednesday will be cooler with temperatures
ranging from the mid-60s to mid-70s.
Friday into the Memorial Day Weekend
The models continue to diverge as they struggle with the placement
of a closed low over the eastern US. It ranges from the eastern
Great Lakes into the Carolinas. In addition, they struggle with
how fast the upper level ridge will break down over the Upper
Mississippi River Valley. Due to this, there is some uncertainty
on when precipitation chances will return to the forecast for late
this week. Even with this uncertainty, there is general agreement
that there will be at least scattered showers and storms for this
time period.
In addition to some uncertainty on the precipitation, there is
greater spread (10 to 20 degrees) in the temperature guidance. The
GEFS continues to have the coldest temperatures and the Canadian
ensemble remains the warmest.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 955 PM CDT Sun May 21 2023
CIGS: surface high pressure starts to edge off to the east while the
ridge a loft starts to build overhead from the west. Clouds will
generally be on the sparse side as a result. However, smoke from
Canadian fires continue to spread southeast and will make for a
milky sky the next few days. Will run with sct250 to account for the
smoke for now.
WX/vsby: no impacts anticipated at this time. RAP model suggests
smoke could be brought to the sfc on Tue, which could result in some
MVFR vsby restrictions.
WINDS: light from the south/southeast.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Boyne
AVIATION.....Rieck
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
858 PM CDT Sun May 21 2023
.UPDATE...
Issued at 858 PM CDT Sun May 21 2023
The forecast remains on track.
UPDATE Issued at 631 PM CDT Sun May 21 2023
Quiet conditions continue with hazy skies from smoke across the
forecast area. Any reduction in visibility from near-surface smoke
looks very limited at this time with a few sites down to 9 SM.
Patchy smoke may reduce visibility down to as low as 6 SM in some
western locations tonight.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 253 PM CDT Sun May 21 2023
An upper level ridge across the Northern Rockies continues to
bring subtle northwest flow into the Northern Plains. Therefore,
elevated smoke from the fires up an Alberta continues to move
through the region resulting in hazy skies. Near surface smoke has
mostly cleared out of western and central North Dakota with some
sites seeing very minor visibility reductions. The RAP Near-
Surface Smoke does increase smoke coverage across the west this
evening and tonight. Therefore, patchy smoke was added to the
grids through 12Z Monday. Easterly surface winds could limit near
surface smoke across central North Dakota tonight. Smoke will
likely impact the temperature forecast as temperatures struggle to
reach the lower 80s this afternoon. Smoke will keep low
temperatures elevated tonight in the 50s across the state.
Temperatures are forecast to climb into the lower to mid 80s
across the state. As a low level thermal ridge extends up
through eastern Montana. Smoke could limit temperatures tomorrow a
degree or two. The surface pressure gradient will tighten up
increasing winds out of the south by tomorrow afternoon.
.LONG TERM...(Monday Night through Sunday)
Issued at 253 PM CDT Sun May 21 2023
An upper level ridge is forecast to move across the Northern
Plains the beginning half of this week bringing forth warmer
temperatures. However, a quick transition to unsettled weather
pattern is expected through the middle of the week.
A ridging pattern will bring in a low level thermal ridge across
the Northern and Central Plains. This will result in increased
temperatures Tuesday with highs forecast to sit in the mid 80s to
lower 90s. A wave and a warm front will move across the northwest
resulting in thunderstorms and showers in the afternoon.
Instability increases across the west with slow storm motion could
lead to locally heavy rain. In addition PWATs are forecast to be
above an inch, around 0.5 inches above normal out west. CSU
machine learning severe weather forecast does highlight portions
of North Dakota for the potential for severe hail.
Troughing will continue to dig across Western CONUS bring in
southwesterly flow aloft. A back door cold front is going to move
through the state Wednesday morning causing increased
precipitation chances. Multiple waves are forecast to move through
the region towards the end of the week increasing precipitation
chances. Temperatures are forecast to sit in the upper 70s to
lower 80s for the remainder of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 631 PM CDT Sun May 21 2023
VFR ceilings and visibility are expected through the period.
Removed smoke from western TAF sites based on visibility in
present obs, as well as those nearby. It`s not entirely out of the
question that KXWA/KDIK could see brief reductions to MVFR
visibility in smoke, but confidence is low in that scenario
occurring at this point in time.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Telken
SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Telken
Area Forecast Discussion
National Weather Service Denver/Boulder CO
807 PM MDT Sun May 21 2023
.UPDATE...
Issued at 800 PM MDT Sun May 21 2023
Another surge of smoke was moving slowly southward this
evening, with the leadng edge, along a line from Fort Collins to
Greeley to Sterling line. In addition was spreading southwest
across the higher terrain of Larimer county as well. Expect this
smoke will cover much of the area late tonight through Monday.
Otherwise it will remain quite overnight, except for some
potential for dense fog over ern Lincoln county.
&&
.SHORT TERM...(This evening through Monday)
Issued at 248 PM MDT Sun May 21 2023
Showers and a few storms have developed over the southern Front
Range mountains and Lincoln County this afternoon. Expect scattered
showers and a few storms across over the high country given a
marginally unstable environment (SBCAPE < 500 J/kg). Expect this to
continue through the early evening hours, mainly over the high
country and favoring the southern Front Range.
Geocolor satellite imagery shows the next (unfortunate) wave of
smoke from the wildfires in west Canada dropping southward toward
Colorado thanks to progression of a shortwave trough. In the next
few hours this will reach the northern Colorado border and by early
evening to the Denver Metro. Some portions of this smoke plume
contain thicker smoke concentrations, quite evident on satellite and
it moves through Wyoming at the moment. Stations in Wyoming have
reported visibility as low as 3 miles. RAP smoke forecast is
consistent with the obs as it brings down a wave of higher
concentration smoke into tonight. With a weak ridge and flow aloft
in place for Monday, smoke will be slower to erode and will
likely be around for the day. Without the smoke, it would have
been a slightly warmer day than Sunday. However, given the smoke,
kept highs similar to Sunday in the low to mid 70s. If smoke is
thick enough, highs may not even reach those values over the
plains. There is a chance for showers and thunderstorms in the
afternoon. Instability and moisture will be marginal, but will
support showers and weak thunderstorms. Ensembles show the better
moisture over the high terrain, so it is likely storms will stay
more confined to the high country and struggle to make it onto the
adjacent plains where it is drier, a bit more stable, and has
smoke present.
.LONG TERM...(Monday night through Sunday)
Issued at 248 PM MDT Sun May 21 2023
Weak ridging aloft will be over Colorado on Tuesday with very
light mid to upper level winds. 500 mb winds may be less than 10
knots. Mostly sunny conditions in the morning will allow for some
weak instability to build in. With the lack of a feature to
provide lift, showers and storms will mainly form over the higher
terrain. A couple of these showers and storms may push onto the
adjacent plains. No severe weather is anticipated but there will
be a flash flood threat over the recent burn areas. Otherwise,
temperatures will be slightly above normal.
Upper level flow will increase slightly on Wednesday as a trough
over western Canada begins to influence our area. There will be
better precipitable water and CAPE values as more moisture arrives.
Some models are hinting at a slight shortwave trough that moves
through which should lead to better coverage of showers and storms.
The NBM PoPS seemed overdone as they had PoPs in the 80s across all
of the I-25 corridor. There just isn`t a strong enough trough or
strong enough upslope flow to warrant PoPs greater than 80 percent
so PoPs were lowered. Soundings would support just enough
instability and low level shear that a storm or two could approach
severe thresholds. However, the severe threat would remain very
isolated.
Recent model runs have been showing a ridge over the Southern
Plains staying slightly farther west than previous runs and that
results in it staying over eastern Colorado Thursday and into the
weekend. If this trend continues, our forecast area would likely
see scattered showers and storms over the mountains with lower
coverage on the plains. A lot can change during this period as it
gets closer. One thing to keep an eye on is the threat for severe
weather. The CIPS analogs continue to show a good signal for some
severe weather along the Front Range. However, there is plenty of
skepticism about this chance of severe weather since the flow
aloft will be so weak. Flow at 500 mb fails to get above 30 knots
during this stretch and the instability will not be on the high
side given the near normal temperatures. Nonetheless, a few severe
hailstorms may be possible. The main weather concern appears to
be flash flooding in the burn areas which is discussed more below.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 513 PM MDT Sun May 21 2023
Smoke should gradually filter back in by mid evening and continue
through Monday. At this time have kept visibility above 6 miles
thru the period. There could be a window on Monday where
visibility may drop to 5-6 miles but confidence is low on timing.
Otherwise northeast winds will gradually switch to more southeast
by 04z and then to drainage by 07z. Winds will be light and
variable Monday morning but become east by aftn.
&&
.HYDROLOGY...
Issued at 248 PM MDT Sun May 21 2023
There will be a limited threat for flash flooding over the burn
areas Monday. Scattered showers and thunderstorms are possible in
the afternoon, but are expected to be lower in intensity. However,
flow aloft will be quite weak. With enough moisture present to
support locally heavy rainfall, it will warrant that limited
threat for flash flooding.
Each day during the long term period will at least have a
limited threat for flash flooding in the recent burn areas. The
storms will be slow moving each day due to weak winds aloft. Tuesday
will have nearly stationary storms but the storms will not be
particularly heavy. Therefore, a limited threat of flash flooding is
forecast for Tuesday. The storms may gain some strength Wednesday
through the end of the week but they will also be moving slightly
faster. Wednesday may be close to having an elevated threat for
flash flooding while the rest of the week and weekend will have a
limited threat for now.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Mensch
LONG TERM...Danielson
AVIATION...RPK
HYDROLOGY...Mensch/Danielson
Area Forecast Discussion
National Weather Service Burlington VT
947 PM EDT Sun May 21 2023
.SYNOPSIS...
A cold front crosses the region late this afternoon into
evening with a few showers around and a slight chance for a
thunderstorm across northern New York. Patchy frost is possible
across the Adirondacks and Northeast Kingdom overnight tonight.
Plentiful sunshine albeit with some Canadian wildfire smoke
aloft is on tap for Monday and Tuesday. A cold front brings the
next chance potential for wetting rainfall with embedded thunder
on Wednesday. The weather pattern turns more unsettled during
the latter half of the week.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 943 PM EDT Sunday...Areal coverage of showers continues to
decrease this evening as expected with developing northwest flow
and drier air advecting into our cwa. Have noted temps continue
to be 3 to 5 degrees warmer, so have made some minor tweaks to
the hrly rate of fall. However, as dwpts continue to drop and
drier air with clearing skies develop, expect rate of hrly temp
fall to increase aft midnight. Did make some minor adjustments
to dwpts, but overall fcst in good shape with some very patchy
frost possible toward sunrise acrs the northern dacks and parts
of northern VT, including the NEK.
Previous discussion below:
It has turned out to be a rather nice day across North Country
with sunshine breaking out albeit with smoke from western Canada
wildfires aloft. A cold front currently approaching the St
Lawrence River valley in Quebec is currently sparking some
isolated to scattered showers. The satellite GLM product is
showing some lightning flashes upstream across eastern Ontario.
After examining the latest RAP soundings and mesoanalysis,
introduced slight chance thunder for our NY zones mainly west of
the I-87 corridor. Any thunderstorms that do form could produce
brief locally moderate rain or downpour. The front will sweep
through our region late this afternoon into the evening hours,
with brief showers and a wind shift from the west to northwest.
Dew points drop from near 50 into the upper 20s and lower 30s
through the evening and overnight hours. It will also help to
clear the smoke aloft albeit only till Monday morning per the
NCEP RAP vertically integrated smoke depiction. The other
consideration for tonight is a brief period of patchy frost
potential, mainly across the Adirondacks and Northeast Kingdom.
Forecast soundings indicate that boundary layer winds should
subside enough outside of the valley locales for temperatures to
fall into the lower to mid 30s for these climatologically
colder spots. Given that all zones are now in growing season,
have hoisted Frost headlines for these zones.
Monday will be quite a bit cooler especially across the northern
half of our CWA. Highs will be in the upper 50s to mid 60s across
northern NY and VT with mid 60s to near 70 for southern VT. Surface
high pressure continues to dominate heading into Monday night but
brief upper ridging begins to overspread the region. So there is a
little more uncertainty with how low the temperatures go on Monday
night and consequently the frost potential despite light winds.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Quiet conditions continue to be favored for Tuesday despite a weak
shortwave passage. Model soundings show very dry profiles with the
most aggressive only showing a shallow layer moisture around 850mb
across portions of the Adirondacks and along the Green Mountain
spine along with a little elevated CAPE. Have kept in some token 5-
15% PoPs in these areas for the potential of a popup shower, but
overall the day should be dry with temperatures seasonally warm in
the low/mid 70s. If any showers do pop, they`ll dissipate after
sunset with a dry and mild night on tap as southerly flow increases
ahead of our next system. Clear skies in the evening, will give way
to increasing clouds after midnight with lows generally in the 40s
to locally lower 50s in the Champlain Valley.
Wednesday will mark a pattern change across the region as a potent
upper level trough and sharp cold front remain on track to dig south
from Quebec through the forecast area. Like yesterday, ensemble
guidance remains very high for measurable precipitation so once
again have gone above blended guidance for PoPs in the likely to low
categorical range. Should be a nice wetting rainfall, with a slight
chance for some embedded thunder with 0.25-0.5" likely across
northern zones, lowering to around 0.20" south. In addition, the
latest GFS and NAM show temperatures falling sharply along the
boundary from mid-day across northern zones and the afternoon south.
Similar to frontal passage this past Tuesday, we`ll likely see high
temps mid-morning to midday in the low/mid 60s north to low 70s
south, then rapidly fall into the 40s north and 50s south through
the evening rush hour.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As the previous forecaster eluded to, big changes in the extended
forecast came with the 00Z NWP guidance, and that continued to be
the trend with the latest 12Z runs. While surface high pressure is
still progged to build in behind the frontal passage Wed/Wed night,
the upper level pattern now features a closed circulation at 500mb
which centers over the region on Thursday, and meanders around the
Northeast through the weekend. This supports more diurnal chances
for showers each day, especially Thursday across northern zones, and
across the entire region again on the weekend. The coldest day of
the period looks like Thursday with highs only in the 50s to maybe
60, and lows in the 30s/40s with areas of frost/freeze possible.
Thereafter though, temps will be more seasonal in the upper 60s to
mid 70s for highs and 40s for lows.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...A cold front continues to make steady
progress across the North Country this evening with a line of
showers pushing southward. Some light rain showers cannot be
ruled out of KSLK and KRUT between now and 2Z but these showers
should have no impact on flight conditions given rain is
expected to be light. Winds at this time are light and variable
but we will see winds shift to the north/northwest in the wake
of the front at around 7-10 knots. Dry air will filter in
tomorrow with clear skies in the forecast coupled with light
north winds.
Outlook...
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: Mainly VFR, with areas MVFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with areas VFR possible. Chance
SHRA.
Thursday: Mainly MVFR, with areas VFR possible. Slight chance
SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: VFR. NO SIG WX.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Frost Advisory from 2 AM to 8 AM EDT Monday for VTZ003-004-006-
007-016.
NY...Frost Advisory from 2 AM to 8 AM EDT Monday for NYZ027-029>031-
034.
&&
$$
SYNOPSIS...Chai
NEAR TERM...Chai/Taber
SHORT TERM...Lahiff
LONG TERM...Lahiff
AVIATION...Clay
Area Forecast Discussion
National Weather Service Columbia SC
1045 PM EDT Sun May 21 2023
.SYNOPSIS...
A weak front will stall just to the south of the area later
tonight and remain stalled just south of the area through
Tuesday keeping chances of showers over the southern half of the
forecast area. High pressure and dry weather are expected for
Wednesday into next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Late-evening surface observations depict a west-east oriented
boundary across the southern Midlands. While winds are
northeasterly on both sides of the boundary, there is a distinct
dewpoint gradient, with considerably drier air to the north.
Very isolated light showers persist along and south of the
boundary late this evening, and expect this to continue
potentially into the overnight hours as the boundary sags
slowly south.
Clearing north of the boundary will allow for greater
radiational cooling initially, but lower clouds should redevelop
later tonight. Farther south, mostly cloudy skies persist, and
ceilings should lower through the night. The difference in cloud
cover and dewpoints will result in a gradient in low
temperatures, with upper 50s north, and lower to mid 60s south.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
High pressure over New England will extend southwestward into the
Midlands early this week. Onshore flow will wedge in cooler
than normal air with highs in the mid 70s to around 80 degrees.
A stalled frontal boundary will be across central Georgia and
coastal South Carolina which is close enough to the southern
Midlands and lower CSRA for a chance of showers. This boundary
gets pushed offshore on Wednesday as high pressure builds in
from the Great Lakes.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A closed upper level low pressure system over the Northeast U.S.
gradually extends its influence later this week and into the
Memorial Day weekend. The primary influence should be below normal
temperatures with highs around 80 and lows in the 50s. This
feature may begin to lift away from The Midlands and CSRA next
Sunday which would allow temperatures to warm to near normal for
the end of May (highs in the mid 80s and lows in the lower
60s).
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
East-west surface dewpoint boundary situated just south of the
Midlands taf sites of cae/cub. Drier air north of this boundary
will continue to try pushing further off to the south overnight,
albeit somewhat slowly. Ceilings will be highly dependent upon
which side of the moisture front sites are on. Guidance
indicating that cae/cub and even ogb will be on the northern
side of the front, and with drier air trying to take over they
are showing mainly vfr conditions through the period at those
locations. One fly in the ointment is the hrrr and nbm still
showing lower mvfr ceilings getting close in the Midlands. Will
include at least a scattered clouds around 1200 ft later tonight
to hint at that possibility.
Further south in the CSRA sites of ags/dnl, airmass will be a
little moister through the night. This would seem to indicate a
potential for ceiling restrictions for a good portion of the
overnight. Guidance remains rather bullish on mvfr or lower
after midnight, with ceilings remaining down through 15z Monday
morning. A return to vfr then becomes possible as the drier air
finally pushes through the CSRA and better mixing begins to
scour out the lower clouds.
Winds at all sites mainly light and out of the northeast
overnight, then increase to between 5 and 10 knots late Monday
morning.
EXTENDED AVIATION OUTLOOK...Drier air over the area in the
extended favors lower chances of rainfall and any restrictions
through the period at cae/cub/ogb. Better restriction chances
possible in the CSRA sites of ags/dnl due to being closer to
higher moisture and rain chances each day.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Charleston SC
1050 PM EDT Sun May 21 2023
.SYNOPSIS...
A cold front will stall just to the south through Tuesday as
high pressure builds in from the north. High pressure will
strengthen over the area mid to late week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Late this evening, KCLX detected a few showers across portions
of inland GA and SC. These showers should either push outside
the forecast area or gradually dissipate over the next several
hours. However, the latest run of the HRRR indicates that at
least isolated shower activity may linger into the pre-dawn
hours. The updated forecast will adjust PoP timing and placement
through the overnight hours.
Late tonight, widespread stratus will likely form within the
wedge, but stronger 1000mb geostrophic flow should limit a fog
threat late tonight. Low temps should dip into the low-mid 60s,
with upper 60s/around 70 closer to the coast.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
A cold air damming (CAD) set up looks to form on Monday as high
pressure builds into the region from the north and a cold front
stalls to the south of the area. Aloft a shortwave trough will
ripple across the southeastern states along the southern periphery
of a larger scale trough. Even with the building high pressure at
the surface there will likely be enough upper level forcing to spur
showers and thunderstorms, especially across southeastern GA where
there will be an axis of instability and increased PWAT values.
Scattered to numerous showers and thunderstorms are possible across
southeastern GA with isolated to scattered coverage across
southeastern SC. The temperature forecast will be a tad challenging
as persistent cloud cover across southeastern GA will likely hinder
temperatures, the forecast only has upper 70s. Across southeastern
SC cloud cover may not be as persistent with some sunshine peaking
through and, in spite of the CAD set up, temperatures are forecast
to reach into the low 80s. Overnight lows will dip down into the low
60s far inland with upper 60s to near 70 along the coast.
A similar set up is expected on Tuesday, with high pressure building
at the surface and another shortwave rippling through the
southeastern states. Tuesday will feature a very similar forecast to
Monday, with the greater coverage of showers and thunderstorms
across southeastern GA and temperatures slightly warmer across
southeastern SC. Low temperatures will be a little cooler than
Monday night, with low 60s inland and mid to upper 60s along the
coastline.
High pressure will begin to weaken Wednesday at the surface while
aloft the region will be placed under broad troughing aloft. Lacking
forcing aloft coverage of showers and thunderstorms will be less
than on Monday and Tuesday, with isolated to scattered showers and
thunderstorms forecast, mainly along and east of I-95. Temperatures
are forecast to reach into the mid to upper 70s across the
region.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
There is some discrepancy between the global models regarding the
synoptic set up through the long term period. All models depict a
surface low forming somewhere in the vicinity of the southeastern
coastline, but differ in the intensity and placement of the low.
Regardless of the low offshore, high pressure will be the dominant
synoptic feature across the local forecast area. Precipitation
should be confined to diurnal convection along the afternoon sea
breeze. Temperatures will remain fairly consistent, with highs in
the upper 70s to low 80s and overnight lows in the upper 50s inland
and mid 60s along the coastline.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Prior to the 0Z TAFs: KCLX detected isolated to scattered
showers near the KCHS/KJZI/KSAV terminals. The TAFs will be
initialized with a mention of VCSH. The showers are expected to
dissipate by mid-evening. The primary concern overnight will be
the development of restrictive ceilings. Near term guidance
indicates that a ridge of high pressure will develop over the
area tonight. The combination of low level moisture and weak
forcing should support a deck of stratus across the region.
Forecast soundings and MOS indicate that MVFR ceilings will
develop at KCHS and KJZI later this evening and may linger until
mid-morning on Monday. KSAV should see a greater chance for
restrictive ceilings, with a period of IFR ceilings possible
from 8-12Z highlighted with a TEMPO. Northeast winds are
forecast to develop gusts around 20kts between 15-20Z.
Extended Aviation Outlook: Showers and thunderstorms are possible
Tuesday afternoon, especially around KSAV.
&&
.MARINE...
Tonight: A cold front will slowly nudge south of the area overnight,
followed by high pressure wedging across inland areas in its wake.
The pressure gradient will increase as this process unfolds,
strengthening northerly winds across local water, especially after
midnight. Winds could gust up to 15-20 kt across local waters,
especially across nearshore South Carolina waters late. Seas will
also build upwards to 3-4 ft.
Monday through Thursday: High pressure will build across the region
through the period, leading to increasing NE flow across the local
waters. Wind gusts will approach 25 knots beginning as early as
Monday afternoon, increasing to 25 knot gusts Monday night. Seas
will also build across all waters, with 6 ft seas encroaching on the
Charleston nearshore waters Monday afternoon. Small Craft Advisories
will likely be needed for all marine waters, possibly including the
Charleston Harbor, beginning Monday afternoon. Not much change in
the synoptic set up is expected through the week so the Small Craft
Advisories may last through much of the week as winds and seas
remain elevated.
Rip Currents: Increasing NE winds and building swells will lead to
an increased risk of rip currents Monday through Friday. A Moderate
Risk of rip currents is in effect Tuesday across all local beaches.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...NED
MARINE...CPM/DPB
Area Forecast Discussion
National Weather Service Cheyenne WY
432 PM MDT Sun May 21 2023
.SHORT TERM...(This evening through Tuesday night)
Issued at 330 PM MDT Sun May 21 2023
The main concern with this portion of the forecast is timing of when
the Canadian smoke will disperse.
Latest visible imagery was showing the bulk of the thicker smoke in
the northeast portion of our forecast area. This is tending to
reduce the visibility in northeast Wyoming, but it does not appear
as thick as it was a few days ago. The inversion will once again
settle over the region tonight due to decent subsidence from the
upper level ridge and weak surface high pressure. This will tend to
keep the smoke settled over the forecast area again tonight with
visibilities ranging from 3-5sm. The good news is that the Canadian
and RAP models are showing this smoke dispersing and retreating
further north into the northern Plains tomorrow. This seems
reasonable considering the smoke tended to disperse today. The smoke
should also continue retreating further north on Monday night and
Tuesday as the southwest flow starts kicking in west of the I-25
corridor and southerly flow returns to areas east of I-25.
Overall, the upper level ridge will continue to keep its grip over
the region on Monday and allow for another pleasant day. Cannot rule
a few isolated showers over the Snowy and Sierra Madre range and
Ferris mountains. The models are keying in on surface low pressure
developing over northern Wyoming in response to the closed low
moving into the northwest U.S Monday evening. This may induce some
gusty winds over Carbon county tomorrow evening, but the remainder
of the region will be relatively quiet.
Tuesday into Tuesday night the models/ensembles are showing the
upper level ridge slowly moving east in response to the upper level
closed low in western Canada slowly advancing east. This will allow
for some better return flow and moisture advection into the region
mainly along and west of the I-25 corridor. We did pull
precipitation chances back further west than what the National Blend
of Models advertised due to lack of instability east of I-25 and
mainly southerly steering flow. However, further west of I-25 we may
be looking at more scattered showers and thunderstorms. We will need
to keep an eye on the mountains for any convection potential
especially with rain on snow.
.LONG TERM...(Wednesday through Sunday)
Issued at 330 PM MDT Sun May 21 2023
The long term weather pattern continues to remain consistent as an
active weather pattern and slightly above average temperatures are
forecast. A blocking pattern for weather systems to shift from west
to east will occur for the medium range to extended forecast as a
upper level trough remains over the Northeast, retrograding to the
Great Lakes region. Typically this would mean that the upper level
ridge pattern that would be stuck over the Central Plains and
Intermountain West would result in dry conditions and above average
temperatures for our cwa. However, a favorable weather pattern for
the Central Rockies will take shape as a pronounced upper level
trough will dig south along the CA coastline. Thus, the upper level
"dirty ridge" will be supplanted by continual surges of favorable
atmospheric dynamics from the upper level low further upstream along
the CA coastline and Four Corners region. The upper level low is
progged to remain semi-stationary for a few days. This lines up well
with the CPC 6-10 Day and 8-14 Day Outlook for chances of above
average precipitation and above average temperatures.
A shortwave disturbance will propagate along and ahead of the semi-
stationary upper level low off the CA coastline Wednesday toward our
cwa. A jet streak of 40-45 knots further upstream should provide
enough diffluent flow aloft for convection to initiate by the
afternoon hours, likely starting off west of the Laramie Range and
propagating to the east. However, shear is not looking particularly
fruitful for long-lived convection. Additionally, the 700-500mb
lapse rates are displaced from the best moisture PWATs, which will
be east of I-25 between 0.5 to 1.2 inches on Wednesday. This is
modeled by the GFS and NAM. MUCAPE values upwards of 1000 J/kg could
provide enough instability after the convective temperature is
achieved for a few strong thunderstorms, but severe weather may not
be achieved for Wednesday afternoon and evening. The "x-factor" may
be the modeled GFS 0-3km storm relative helicity that will be
strongest across the NE Panhandle, should model consistency persist.
With the weak steering flow aloft, this should be a good opportunity
for rainfall in localized areas.
Thursday appears to be the best opportunity for strong to
potentially severe thunderstorm activity this week, as long as
models continue to show a consistent signal. The LLJ signal, MUCAPE
values in excess of 1500-2500 J/kg, EBWD shear of 30-40 kts, steep
lapse rates, and SRH values in excess of 100-250 m^2/s^2 for areas
east of I-25. This coupled with abundant moisture as PWATs may surge
to thresholds of 1 to 1.5 inches. This is well above the 90th
percentile for PWATs across the high plains. Heavy rainfall may also
accompany this favorable setup for slow-moving thunderstorms on
Thursday afternoon and evening. Deterministic model GFS soundings
are hinting at SVR to potentially TOR conditions. Will continue to
monitor the trends the next couple of days in the event that
messaging needs to be done to advertise the potential for strong to
severe weather.
Friday also looks to be potentially active as the afternoon to
evening hours will have similar weather conditions to the previous
days. Slow-moving thunderstorms may trend towards the strong to
severe category if atmospheric dynamics, instability, surface
forcing, and moisture combine east of the Laramie Range. Total QPF
values per the GFS between Wednesday and Friday night could total
between 0.5 to 2+ inches. We welcome the opportunity to have
continued impulses of moisture across the region to assist with the
prolonged drought conditions.
The weekend is forecast to start off on the active category as
daytime opportunities for thunderstorms persists on Saturday. This
looks to be the last chance of rainfall, which may be a welcomed
relief to those that may be planning to do outdoor activities next
weekend. Sunday is anticipated to be mild and dry. Thunderstorms are
possible south across CO, but it looks to stay outside of our cwa at
this time. Despite the active weather pattern signal for the coming
week, the above average temperatures should be a welcomed sight
instead of any strong cold front we typically see by Memorial Day
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 430 PM MDT Sun May 21 2023
No major changes for the next 6 hours, with much of the forecast
remaining on track. Lowered visibilities are expected to
continue, with the current wind direction advecting smoke across
the region from fires to the north. Expecting these conditions to
continue till winds begin to turn more west to southwesterly, and
as a result, should begin to see the skies and visibilities lift.
At this time, the smoke will likely not clear over the next 24
hours, with HiRes model guidance not having a decent southwesterly
wind shift till late Monday into early Tuesday. Areas of fog will
be possible again early tomorrow morning, with temporary LIFR
conditions possible.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Sun May 21 2023
Very low relative humidities of 20 to 30 percent are expected during
the next couple of days in response to the strong upper level ridge.
However, wind speeds will be fairly light which will limit any fire
spread. The remainder of the week, low level moisture will be on the
increase. This combined with moist fuels will limit any critical
fire weather threat.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...REC
LONG TERM...BW
AVIATION...MRD
FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Dodge City KS
547 PM CDT Sun May 21 2023
...Updated Aviation...
.SHORT TERM...(This evening through Monday night)
Issued at 109 PM CDT Sun May 21 2023
Water vapor satellite imagery and RAP upper air analysis at 1730Z
Sunday depicts a rather nebulous 500-mb pattern, with a lone,
weak shortwave trough over the northern plains on the eastern
periphery of a weak longwave ridge over the western CONUS.
Resulting marginal DNVA over the central plains is keeping the
skies mostly clear over southwest KS, save for a thin layer of
cirrus which will likely shave a few degrees off the afternoon
highs today. At the surface, the MSLP pattern is similarly ill-
defined, with a weak lee trough in eastern CO supporting 10-20 mph
upslope southeasterly winds. Accounting for the somewhat limited
solar insolation and the lack of appreciable WAA, afternoon highs
will be near or just below normal, maxing out in the upper 70s to
low 80s.
Short range guidance/HREF both suggest the aforementioned weak
upslope flow will allow for at least some moisture advection, and
eventually support afternoon thunderstorm development across the
higher terrain of southeast CO and adjacent northeast NM. In
fact, recent visible satellite imagery shows the beginnings of a
cumulus field over this area, suggesting thunderstorm initiation
could occur within the next couple hours. Once thunderstorms
initiate, convection will expand eastward in coverage, however the
degree to which these storms reach into the DDC CWA is still in
question given the weak steering flow. Current thinking is
thunderstorms will at least reach the US-83 corridor before a
stabilizing boundary layer chokes updrafts of CAPE after sunset.
Severe weather is not currently expected as bulk shear will remain
weak (<25 kts), but 500-1000 J/Kg of CAPE will exist across the
western zones and could support brief, marginally severe hail
within the strongest storms.
Showers may linger into the morning Monday as CAMs hint at a weak
MCV developing from the previous night`s convection just south of
our area, which would indeed support a localized area of
increased convergence that could sustain enough ascent for
precipitation, but pinpointing where these showers will be is a
fool`s errand. Regardless, overcast skies will be maintained as a
result of the MCV, leading to a slightly cooler afternoon Monday
with highs in the low 70s. Renewed thunderstorm development is
possible Monday afternoon based on HREF guidance, however low
confidence in spatiotemporal details significantly limits
predictability.
.LONG TERM...(Tuesday through Sunday)
Issued at 218 PM CDT Sun May 21 2023
Key messages: several days of showers and thunderstorms appear
possible through the week, with little to no severe threat.
Temperatures will stay at or just below normal.
Medium range ensemble guidance indicates upper level ridging will
be maintained over southwest KS through the long term period,
with deepening troughs to the west and east of the ridge as we get
further into the week. These features will allow surface
troughing in the lee of the Rockies to continue as well,
supporting nearly constant moisture advection from the southern
plains into our area via southeasterly winds. As a result, showers
and thunderstorms will be possible every day during the long term
period, which is reflected in the GFS/ECMWF ensemble members of
which all show at least some QPF across the area. Better yet, the
weak upper level flow should remove any widespread severe threat
entirely, with only brief, isolated severe events possible. Given
this very wet pattern, high temperatures will likely stay in the
70s to low 80s throughout the period as well under abundant cloud
cover.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 545 PM CDT Sun May 21 2023
Showers and thunderstorms are developing west of GCK and LBL and
will have VCTS for those areas from after 00Z through 12Z. Storms
will move east and could affect the DDC terminal around 04-15Z and
the HYS terminal from 08Z-18Z. Main threat with the storms could
be some brief heavy rains that would lower visibility but no
severe weather is expected. Outside of the storms the flight
categories should stay mainly VFR but could get close to MVFR
flight category for Monday morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 55 73 55 74 / 30 50 50 30
GCK 55 71 55 72 / 50 40 30 20
EHA 53 76 55 76 / 60 40 30 20
LBL 55 75 55 74 / 50 40 40 20
HYS 55 73 55 77 / 30 40 40 40
P28 55 76 58 75 / 20 50 50 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Tatro
Area Forecast Discussion
National Weather Service Des Moines IA
639 PM CDT Sun May 21 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Sunday/
Issued at 230 PM CDT Sun May 21 2023
Key messaging highlights:
* Continued warm temperatures through the period
* Mainly dry with only infrequent token slight chances until
possibly late next weekend
There is little change from previous expectations with a fairly
inactive period through at least the end of the week. Although
there is a compact PV anomaly across SD this afternoon, and a
minor ribbon of theta-e advection ahead into the Siouxland area,
it will be insufficient for much beyond patchy mid clouds with
moisture still lacking. A subtle NE upper wave, along with broad,
weak southern stream lift into steep mid/high level lapse rates
will also continue to spread cirrus/cirrocumulus into IA tonight
and early Monday. The GFS and NSSL WRF are also hinting at very
weak convection tomorrow afternoon, but the forecast will be left
dry until guidance consensus increases or trends suggest
otherwise. Some smoke aloft may also increase into Iowa over the
next two days, especially north. Confidence isn`t the greatest
however as the extended 15Z RAP appears to have over initialized
smoke and any southern trajectories across MO
Going into Tue and Wed, central CONUS ridging will continue to
expand leaving IA in very weak flow through the column with
<=15kts of wind through 25,000ft at times. The GFS, NAM and CMC
all hint at unorganized weak convection Wed afternoon in steep low
level lapse rates, so will keep slight chances central and south,
but if any occur they should fade quickly with the loss of
heating. This will be followed by a backdoor cool front, with some
depth, that is driven by the passage of a northern/eastern Great
Lakes upper trough. After a few days with highs in the 80s, this
will briefly drop temps back several degrees but still stay above
normal, and also reinforce what continues to be a seasonally dry
airmass. 40s dewpoints (or less) will be more common than 50s
through the end of the week.
The pattern may eventually start to break down later in the
weekend as weak southwest flow short waves attempt to chip away at
the upper ridge, possibly starting a return of moisture to some
depth, especially to the west. The flow will remain weak however
so the severe potential will remain low with anything that could
develop.
&&
.AVIATION.../For the 00Z TAFS through 00Z Monday evening/
Issued at 637 PM CDT Sun May 21 2023
VFR conditions to prevail through the period with scattered
cumulus probable in the daytime tomorrow along with light
southeast winds.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Small
AVIATION...Jimenez
Area Forecast Discussion
National Weather Service Quad Cities IA IL
606 PM CDT Sun May 21 2023
...00Z AVIATION UPDATE...
.SYNOPSIS...
Issued at 210 PM CDT Sun May 21 2023
Beautiful late May weather occurring today, with surface high
overhead bringing plenty of sunshine, comfortable humidity, and
temperatures in the 70s. GOES visible satellite loops show some high
clouds moving over central IA and some smoke over the Dakotas
from Canadian wildfires. A shortwave was accompanying the smoke
over the northern Great Plains.
&&
.SHORT TERM...(This evening through Monday)
Issued at 210 PM CDT Sun May 21 2023
Key Message:
1. Dry conditions continue, with seasonable temperatures tonight.
Another pleasant day Monday to start the work week, with
temperatures a few degrees warmer than today.
Tonight...Surface high to slide off to the east with weak return
flow developing overnight. This will keep lows several degrees
warmer than in previous days only dropping into the lower 50s.
Another great night to keep the windows open.
Monday...mostly sunny skies, light south wind, and low dewpoints
will boost afternoon temps into the lower 80s. Some wildfire smoke
may be getting close to the CWA late in the day across northern IA
and southern MN per latest RAP run of vertically integrated smoke.
No near surface smoke is anticipated.
.LONG TERM...(Monday night through Sunday)
Issued at 210 PM CDT Sun May 21 2023
Key Message:
1. Above normal temperatures, although not as warm as in recent
model runs, and dry conditions will be seen through the rest of the
work week and into the holiday weekend.
Monday night-Tuesday night...building upper level high in the
central Plains will bring continued dry conditions and above normal
temperatures. Dry soils and dry surface conditions will bring large
diurnal temperature swings as much as 28 degrees from Monday night
lows in the middle 50s to Tuesday highs in the low 80s.
Wednesday-Sunday...A backdoor cold front will push through the CWA
from northeast to southwest during the day on Wednesday. Forecast
soundings and dry 1000-500mb RH layer progs suggest only an increase
in clouds with the fropa and have kept the forecast dry. The speed
and timing of the front will be key to highs on Wednesday, with
northern IL favored for the cooler readings near 70 degrees to the
lower 80s in southeast IA, northeast MO, and west central IL. A
faster movement of the front may bring somewhat cooler
temperatures closer to the Quad Cities. The NBM while still on
the higher end of model guidance has started trending cooler
through the period and 90+ degree readings now appear unlikely
through the holiday weekend. The coolest timeframe through the
extended will be Wednesday night and Thursday when the cooler
northeast air, per 6 to 9C 850mb temperatures arrive. Dewpoints
will drop into the 30s Wednesday night with lows in the upper 40s
to low 50s. Taking a look at the holiday weekend, most model
solutions keep us dry through at least Saturday night, with
temperatures in the upper 70s and low 80s. The 12z GFS brings a
compact shortwave through the area Saturday night and for this
reason slight chance PoPs were kept in the forecast. This will
change however and chances are this may be delayed even later in
the weekend. With the Gulf closed and an upper low off the east,
not anticipating much QPF at this juncture if this materializes in
later forecasts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 606 PM CDT Sun May 21 2023
VFR conditions expected throughout the TAF period. Some high-level
clouds will linger into the overnight hours tonight. Then, some
daytime cumulus clouds are expected to develop by late morning
into the afternoon hours, with ceilings generally around 5 kft.
Southerly winds of 5 to 10 knots expected Monday.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Gross
SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Schultz
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
521 PM MDT Sun May 21 2023
...New AVIATION...
.SYNOPSIS...
Issued at 1259 PM MDT Sun May 21 2023
Afternoon thunderstorm chances will linger through early next
week. Dry air and hot temperatures will build in mid week with
winds remaining breezy to light. Hot and dry will persist through
the end of the work week, with gusty winds moving in next weekend.
&&
.DISCUSSION...
Issued at 1259 PM MDT Sun May 21 2023
Scattered convection has been forming over the Gila Region this
afternoon. Storms depict heavy down pours, lightning, small hail,
and gusty outflow winds. CAMs have shown more aggression with
moving out the surface moisture (saying southwest winds will form
near the NM Bootheel and kick it out in the next few hours),
however observations relay dewpoints are still in the mid to upper
40s and low 50s for most of the area. Observations have been
around 5 to 10 degrees more moist than the HRRR or RAP.
With more moisture near the surface, CU have been building over
most counties (with the exception of the eastern Otero lowlands).
With all this said, confidence with afternoon thunderstorms for
most lowland areas is low and mostly clouds and outflows will be
seen. Can`t rule out an isolated storm somewhere along the RGV or
east but chances will diminish later this evening fairly quickly
as the trend is still to dry out.
An upper level wave to our west will try to move westerly winds
and drier air in every afternoon through Tuesday. Chances for
afternoon thunderstorms will be mainly in the higher terrain and
east but even those will be isolated as the drier air pushes in
more Monday and then Tuesday. Temperatures will be warming a few
degrees every day as well with south to southwest winds lightly
breezy in the afternoon hours.
Mid week an upper level ridge start to take shape with the axis
lying over Otero and Hudspeth Counties. Temperatures will warm to
above normal (approaching the high 90s in desert lowlands). At the
same time an upper level low start to move onshore near central
CA. Stronger winds aloft will move over the western areas of the
CWA, and create marginally gusty southwest winds. This pattern
will stall, making the end of the week fairly unchanged from mid
week (hot temperatures, dry air, and breezy afternoon winds). Some
chances for a dry line intrusion exist for far east areas but
chances remain low.
Next weekend the low over CA is forecasted to move eastward and
bring gusty southwest winds and dry air over most of the CWA.
Returning typical spring to us.
&&
.AVIATION...
(00Z TAFS)
Issued at 520 PM MDT Sun May 21 2023
Unlike yesterday, convection is slowly beginning to fade. The main
threat from the few thunderstorms that are left are the outflow
boundaries. It is not likely that any of the main TAF sites will
be impacted by one of the outflow boundaries, but Holloman AFB and
KALM could see some strong surface wind gusts for the next couple
of hours. Otherwise our west winds will continue this evening,
with a couple of low end wind gusts. Wind will continue out the
west tonight, or will go light and variable. On Monday we will see
more west winds with low end wind gusts in the afternoon.
Currently we have some mid clouds across the region, as we move
more into the evening hours, we will see less and less of them,
but we may have an occasionally high ceiling of SCT-BKN250. We
will see even less clouds tomorrow, though I can`t rule out a
thunderstorm or two, mainly in area mountains.
&&
.FIRE WEATHER...
Issued at 1259 PM MDT Sun May 21 2023
Low risk for fire weather conditions expected over the next few
days. We are going to be generally dry with minimum relative
humidity dropping to below 15% in zone 111 today, then
extending into the rest of the lowlands tomorrow. The Sacramento
Mountains remain generally above 15%. There will be enough
moisture for showers and thunderstorms today across most of the
area, except for zone 111. Then convective activity is limited to
area mountains on Monday. We will be mostly dry for the rest of
the week except in zones 113 and 056, where storms are possible
due to the dryline settling in the eastern edge of our region.
Winds become from the southwest this afternoon. This will be the
prevailing direction through the week keeping the dryline out
east. Wind speeds should be around 5 to 15 mph. Ventilation rates
will be good to excellent through the week.
Next weekend, the passage of an upper system to our north will
lead to breezy to windy conditions. This will raise the risk of
fire weather conditions to elevated and near critical.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 64 94 66 97 / 0 0 0 0
Sierra Blanca 57 86 58 90 / 10 20 10 0
Las Cruces 59 92 60 95 / 10 0 0 0
Alamogordo 56 87 58 90 / 30 10 0 0
Cloudcroft 44 63 46 66 / 30 10 0 0
Truth or Consequences 56 87 59 89 / 10 10 0 0
Silver City 53 80 55 82 / 10 10 0 0
Deming 55 90 56 92 / 10 0 0 0
Lordsburg 55 88 56 89 / 0 0 0 0
West El Paso Metro 63 90 65 93 / 0 0 0 0
Dell City 55 91 56 95 / 10 10 0 0
Fort Hancock 58 93 60 96 / 10 10 0 0
Loma Linda 58 84 60 86 / 10 10 0 0
Fabens 60 92 62 94 / 10 0 0 0
Santa Teresa 58 88 59 92 / 0 0 0 0
White Sands HQ 63 89 65 92 / 10 10 10 0
Jornada Range 55 87 56 90 / 10 10 10 0
Hatch 56 88 57 92 / 10 10 0 0
Columbus 59 90 61 92 / 0 0 0 0
Orogrande 56 88 58 91 / 10 10 0 0
Mayhill 47 76 49 79 / 20 10 0 0
Mescalero 46 75 48 78 / 40 10 10 0
Timberon 45 74 48 77 / 10 10 0 0
Winston 48 76 49 79 / 20 20 0 0
Hillsboro 53 85 55 88 / 10 10 0 0
Spaceport 54 86 55 89 / 10 10 10 0
Lake Roberts 47 81 49 83 / 10 10 0 0
Hurley 52 86 53 89 / 10 10 0 0
Cliff 45 88 45 90 / 10 10 0 0
Mule Creek 52 83 53 85 / 10 10 0 0
Faywood 55 84 55 86 / 10 10 0 0
Animas 55 88 55 90 / 0 0 0 0
Hachita 56 89 56 91 / 0 0 0 0
Antelope Wells 55 88 56 90 / 0 0 0 0
Cloverdale 58 83 56 84 / 0 0 0 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
SHORT TERM...99
LONG TERM....99
AVIATION...15-Brice
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1022 PM CDT Sun May 21 2023
.SHORT TERM...(This Evening through Monday Afternoon)
Issued at 230 PM CDT Sun May 21 2023
KEY MESSAGES:
1. Spotty high-based showers, perhaps an isolated storm, possible
this evening.
2. Canadian wildfire smoke will continue to impact the area early
this week, mostly aloft, but could see minor visibility restrictions
and air quality issues.
3. Mostly dry through the week, but upcoming Memorial Day weekend
could be more unsettled at times.
--------------------------------
Compact wave sliding into southeast SD this afternoon is clearly
visible on water vapor imagery, as well as some visible imagery in
which the spin is evident in the smoke layer aloft. As of early
afternoon, starting to see scattered cumulus develop from west of
Yankton into north central Nebraska near weak convergence boundary.
Will watch this area extending northeast toward KMHE-KBKX for spotty
showers, perhaps a few storms given some weak instability in the
area from mid-late afternoon into this evening. Forecast soundings
show fairly narrow CAPE profiles, with a deep dry layer below 750mb
cloud layer, so not sure how much precip will be realized at the
surface. However, the dry layer could locally enhance gusty winds
near any virga and/or showers.
Similar setup in our extreme western counties for Monday afternoon,
minus the added weak lift from the compact wave. Will add sprinkles
to the area for now, and let later shifts evaluate further after we
see how today pans out.
Aside from these minor precip chances, the main story will be the
return of some thicker smoke aloft. While not apparent on midday
satellite imagery, we have seen the milky white sky here in Sioux
Falls most of today, with thicker smoke which is more easily seen on
satellite poised off to our west. This is handled well by latest RAP
smoke model, which slowly expands the thicker smoke aloft back over
our forecast area overnight into Monday. With continued southerly
flow and little change in the low level thermal profile, high temps
should end up close to today`s readings in the upper 70s-lower 80s.
As far as the lower levels, the weak low level boundary near our
western CWA should keep the more impactful near surface smoke west
of the forecast area, though cannot rule out some minor haziness in
our far west near the convergence axis. At this point, confidence is
not high enough to include in the forecast.
.LONG TERM...(Monday Evening through Sunday)
Issued at 230 PM CDT Sun May 21 2023
The midweek period Tuesday-Thursday will feature a broad upper
level ridge across the nation`s midsection. Northeast to eastern
parts of the forecast area may be feel a subtle influence from a
back-door cold front, pushing south through the Mississippi and
Ohio River Valleys Wednesday into Thursday. Precipitation chances
with this feature seem to largely remain east of our area, but we
could see cooler temps in our MN/IA counties, depending on how far
west the boundary progresses. The upper ridge should largely keep
the area dry. However, as the ridge axis begins to shift east on
Thursday, weak waves lifting through the western periphery of the
ridge could bring a few showers or storms to our western counties
Thursday afternoon/night.
Models diverge on how quickly to break down the upper ridge as we
head into the upcoming Memorial Day weekend, but there is general
agreement that Friday-Sunday will become more unsettled, with
periodic chances for showers and storms. Mid-upper level flow
remains rather weak, lending to weak deep layer shear. So while
instability may support scattered storm development that could
impact outdoor plans, the potential for organized severe storms
is low. As far as temperatures, broad consensus keeps readings
above late May normals throughout the period, so current trends
are pointing to a warm and muggy holiday weekend befitting the
unofficial start of Summer.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1020 PM CDT Sun May 21 2023
VFR conditions persist overnight. Scattered mid-lvl clouds will
remain in place into Monday, along with a thick high level smoke
layer.
We`re seeing very isolated visibility reductions late this evening
due to smoke/haze, but visibility less than 6 mile should remain
very isolated.
With a bit of lift lingering overnight and mid-lvl ACCAS, an
isolated shower is possible towards daybreak, but too limited in
coverage to mention.
A diurnal cloud field will redevelop by mid-day Monday as winds
stay southerly. Thick smoke aloft will remain.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...JH
LONG TERM...JH
AVIATION...Dux
For this long-term forecast discussion, an active weather pattern is
expected to set-up across the High Plains beginning Wednesday and
persisting through the end of the week. Given that this is May,
several days of severe thunderstorms can be anticipated as the
shortwaves eject over the Plains and a persistent dryline remains
fairly stationary along and west of the Colorado border. We`ll go
through the set-up day by day as each day has subtle differences
that will lead to changes into the anticipated threats/impacts.
First, let`s talk about the overall upper level pattern. Beginning
with Wednesday, the High Plains will be situated under a ridge of
high pressure. However, a trough of low pressure will begin
deepening over the western United States. As this happens throughout
the week, it should begin to progress slowly, very slowly, towards
the Great Plains. The upper level jets will amplify, and this should
be favorable for the development and deepening of a surface trough
of low pressure in lee of the Rockies. This low pressure system will
serve to hold the dryline back further west, preventing it from
surging east out of the region. In addition, persistent southeast
winds will continue to tap a large reserve of warm, moist air moving
northwest from the Gulf of Mexico. All of this being said, there are
many factors favoring an active time period from mid-week and into
the weekend which could lead to several days of severe thunderstorms
and heavy rainfall.
On Wednesday, current projections are that the dryline will be
somewhere in eastern Colorado, which would open up the entire
forecast area to the potential for strong to severe storms. Guidance
does suggest that widespread cloud cover is possible due to the flow
of moisture into the region, which may be problematic for the
instability ingredient for this event. In fact, that does show up in
the forecast SBCape with only 500-1000 j/kg forecast in most of the
warm sector, except along the dryline where breaks in the clouds may
lead to readings approaching 1500 j/kg. The impact of cloud cover is
also visible in the projected lapse rates, which are in the 5-7 C/km
range in most of the warm sector save immediately along the dryline
where readings may reach 8 C/km. For Wednesday, the wind shear
parameters can be described as poor for most of the area, although
portions of east central and southeast Colorado may see 0-6 km bulk
shear values of around 30 kts. Elsewhere across the NWS Goodland
service area, 0-6 km bulk shear of 20 to maybe 25 kts is
anticipated. The same story is true for helicity parameters.
Finally, precipitable water values should climb into the 1.00-1.00
inch range, which is approaching the 90th percentile for this time
of year. In the end, it seems there is enough support for severe
thunderstorms to occur on Wednesday although any shortwave trough
initiating these storms will be weak/subtle. Could see some
organized severe storms, and perhaps supercells across eastern
Colorado. Heavy rainfall would also be possible, especially since
storm motion isn`t terribly high and some areas have received
plentiful heavy rainfall recently.
On Thursday, the setup is a little more concerning, mainly in terms
of the instability and shear parameters as the general upper level
and surface setups remain fairly unchanged. For instability, SBCape
climbs to a concerning 1500-2500 j/kg and lapse rates of 7-8.5 C/km
along the dryline. 0-6 km bulk shear of 35-40 kts and 0-3 km
helicity of 150-200 m2/s2 is also concerning. With storms firing on a
north to south oriented dryline and moving southeast, it`s possible
scattered supercells capable of all modes of severe weather occur.
In addition, pwats of 1-1.10 inches again, paired with storm motions
of 10-15 knots, will be a prime setup for heavy rainfall and
potential flash flooding. Thursday will be a day to keep a close eye
on for a possible outbreak of severe storms.
For Friday, a very similar setup to Thursday is anticipated. The one
main difference seems to be a weakness in the wind fields at the mid-
levels, which reduces the available wind shear for organized severe
weather. That being said, severe storms and heavy rainfall will
certainly be possible once again. One other concern leading to some
uncertainty with this potential event is that with more widespread
severe weather possible on Thursday, I wonder how impacted the
environment will be on Friday from the previous day`s storms. This
will be something to watch as in years of experience, it seems
difficult to get multiple significant days of severe weather in a
row unless there is a substantial cut-off low pressure system
causing it. With weak upper level support for these events, it is
possible that Friday turns out to be a lower-end day but not a non-
zero one.
On Saturday, guidance is differing on the upper level pattern as
some model members are suggesting a stronger, negatively-tilted
shortwave trough ejecting over the High Plains. However, some
members suggest this shortwave moves through on Sunday instead,
leading to some uncertainty on Saturday`s storms. Wind shear still
isn`t terribly strong due to weaker mid-level winds, although they
are supposed to strengthen some, particularly if a stronger
shortwave and wind maxima materializes. Cape and pwats won`t be a
problem for the severe weather and heavy rainfall threat. With the
dryline remaining along the Colorado border, most of us will once
again see a threat for severe storms.
Finally, whew, for Sunday, a bit of uncertainty remains due to
differing solutions with the negatively-tilted shortwave that is
anticipated to move out over the Plains at some point this weekend.
It does appear the surface low begins to meander east, and some
solutions depict a cold front sagging south into the region. This
uncertainty in surface features will have drastic impacts on the
potential severe weather setup on Sunday. For now, I won`t dive into
the details...the key message would be there remains potential for
strong/severe storms and heavy rainfall going into the end of the
holiday weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 504 PM MDT Sun May 21 2023
Both terminals will be impacted with MVFR visibility 3-6sm in
patchy smoke. KGLD will see VCTS from 00z-02z. Ceilings
OVC009-011 from 12z-16z Monday.
Winds for KGLD, south around 10-15kts through 12z Monday then
light/variable. By 16z, southeast 5-10kts. Winds for KMCK,
light/variable through 16z Monday, then southeast around 10kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...076
LONG TERM...RRH
AVIATION...JN
Area Forecast Discussion
National Weather Service Grand Rapids MI
753 PM EDT Sun May 21 2023
LATEST UPDATE...
Aviation
.SHORT TERM...(This evening through Monday night)
Issued at 255 PM EDT Sun May 21 2023
-- Dry tonight, few sprinkles possible Mon --
GOES visible imagery shows extensive upper-level smoke continuing to
stream into the region, originating from ongoing wildfires in the
western provinces of Canada. RAP guidance has handled the evolution
of this smoke well, and suggests that appreciable smoke
concentrations aloft will remain over much of Lower MI at least
through Tue, but with a sharp southern edge. Given relatively modest
surface smoke concentrations, smoke impacts will be mainly
optical/radiative, yielding a milky sky and marginally suppressed
temps during the daytime, but with no significant effect on
overnight temps (smoke is essentially transparent in most of the IR
spectrum).
A diffuse surface high currently over the mid MS Valley will shift
eastward tonight and weaken. Meanwhile, a stronger high centered
over northern Ontario will build into southwestern Quebec overnight.
As this occurs, a surface cold front over the northern Great Lakes
will advance southward, then become quasi-stationary over Lower MI
on Mon. Modest low-level convergence along this weakening front,
combined with a subtle increase in boundary-layer moisture (surface
dewpoints likely reaching the low/mid 40s F into central Lower MI),
may support a few sprinkles beneath any deeper cumulus clouds on
Mon, mainly over the northern/eastern forecast area. However, RAP
forecast profiles exhibit fairly high LCLs atop a dry, well-mixed
subcloud boundary layer, suggesting that evaporation/virga will be
considerable beneath any precipitating clouds.
.LONG TERM...(Tuesday through Sunday)
Issued at 255 PM EDT Sun May 21 2023
We continue to look at a mostly dry forecast into next weekend, with
just a couple of small chances for light rain around Wednesday and
next Sunday.
The upper air pattern through the long term will be characterized as
an omega block with long wave troughing over both of the CONUS
coasts, with an upper ridge centered over the Plains. We will
downstream of the upper ridge, allowing for mainly dry weather under
strong subsidence. There will be a few weak short waves that will
spill over the ridge, and try to clip the area.
A ridge of high pressure at the sfc will continue to foster warm and
dry conditions for Tuesday. 850 mb temps under max heating will
allow for temps to sneak up around the 80 mark away from Lake
Michigan.
Then on Wednesday, a fairly strong upper wave will be spilling over
the upper ridge, and across Ontario and over the NE U.S.. This wave
will drag a backdoor cold front through the area on Wednesday. It is
a fairly strong front with 80s ahead of it, and 60s behind it with
dew points in the 20s. The problems with getting any meaningful rain
from it are the upper energy staying NE of the area, and no moisture
in place or feeding in ahead of it. There may be a few sprinkles or
a light shower, but that would be about it.
Much cooler air will filter in over the area behind the front
starting late Wednesday, and continuing into Thursday. The dry air
behind the front mentioned above will clear things out nicely for
the area, even with another short wave coming through. This will
continue through at least Friday and Saturday of the upcoming
holiday weekend. The only problem there may be would be some
possible frost Wednesday night across interior portions of Central
Lower.
Some uncertainty does appear in the forecast for next Sunday,
whether it would stay dry, or maybe a chance of rain might arrive.
Multiple model solutions and their ensembles have shown the upper
low complex over the East Coast trying to retrograde back to the
west a bit. Depending on how much it would, it could come back far
enough west to bring some rain chances in starting next Sunday. The
ridge to our west will be trying to hold tight. These scenarios are
tough to pin down where exactly the upper lows will rotate.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 753 PM EDT Sun May 21 2023
VFR conditions are in place across the area this evening as high
pressure is situated over the Great Lakes region. Skies are mainly
clear outside of a few cumulus clouds that will quickly dissipate
this evening. Some scattered cumulus is possible again on Monday,
with bases up around 5,000 feet.
Plenty of smoke continues to affect the Great Lakes region from
fires that are distant up in Canada for the most part. This smoke
will remain aloft based on model data and not affect surface
visibility.
There is a threat of some light radiation fog tonight at the
southern TAF sites along I-94 with the best chances between 08z
and 12z. Light winds will be the rule the next 24 hours, under 10
knots.
&&
.MARINE...
Issued at 255 PM EDT Sun May 21 2023
Nearshore winds will likely be dominated by diurnal lake-breeze /
land-breeze circulations into Tue, characterized by weak onshore
flow developing in the afternoons (as is occuring now), then weak
offshore flow developing overnight. Confidence is high that
winds/waves will remain below SCA criteria through Tue.
A weakening cold front will reach northern Lake Michigan later this
evening, then become stationary on Mon. A somewhat stronger cold
front will advance southward over the lake on Tue night and Wed.
Precip along this front will likely be spotty/limited, but north to
northeast winds will develop/increase behind this front. Winds may
reach SCA criteria (22+ kts) from Tue night into Wed, but wave
development will likely be limited by the expected offshore flow in
most areas. The exception may be the vicinity of Big and Little
Sable Points on Wed afternoon, where shore-parallel flow may yield
relatively higher waves.
&&
.FIRE WEATHER...
Issued at 255 PM EDT Sun May 21 2023
We are looking at Fire Danger remaining elevated through this week,
and likely becoming more of a concern over time.
Fire danger this afternoon ranges from moderate across the SE
portion of the area where a wetting rain was experienced on Friday,
to very high across Central Lower where there has been very little
to no rain for a while. Also, Central Lower is where the Jack Pine
Trees are found, and are a volatile fuel at this point in the green
up process. Further south, green up has progressed enough that the
fire danger should not be a problem.
The only rain chances this week really look to be on Wednesday with
a stronger cold front dropping down through the area. This rain is
not expected to be anything that would put a dent in the fire danger
with amounts less than a tenth of an inch or less.
The silver lining in the forecast is that it is likely that we do
not see all three ingredients come together for Red Flag conditions
this week. The days it is warm and dry there looks to be lighter
winds. The days it is windy and dry like Wednesday and Thursday,
temperatures will be lower. This is not to say that the land
management agencies will not request a headline, but the
meteorological conditions do not look to come together. We will
continue to monitor the potential until we can get appreciable
rainfall to lower the danger.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SHORT TERM...Kenyon
LONG TERM...NJJ
AVIATION...Duke
FIRE WEATHER...NJJ
MARINE...Kenyon
Area Forecast Discussion
National Weather Service Northern Indiana
1201 AM EDT Mon May 22 2023
.SYNOPSIS...
Issued at 203 PM EDT Sun May 21 2023
High pressure anchors across the Great Lakes through next week as
dry weather persists. Warm weather starts the workweek with highs
reaching into the upper 70s to lower 80s before trending briefly
cooler Thursday through Friday. Memorial Day weekend will be warm and
dry.
&&
.SHORT TERM...(Tonight through Tuesday)
Issued at 203 PM EDT Sun May 21 2023
Broad sfc ridge will anchor across the Great Lakes this period,
providing continued dry and mild weather as upper ridge begins to
build further in time.
&&
.LONG TERM...(Wednesday through Saturday)
Issued at 203 PM EDT Sun May 21 2023
Backdoor cold front will drop through the area Tue night and will
cool temps some Wed-Fri before warming renews upstream of blocky
east coast centered upper troughing. Lots of model uncertainty
toward next weekend with where this slow moving feature sets up
however degree of upper ridging wwd of this sys looks to make for a
very warm Memorial Day.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1151 PM EDT Sun May 21 2023
A stagnant pattern will persist with weak high pressure over the
area. Winds will remain light. Patchy shallow ground fog is likely
by daybreak, but it is not expected to be operationally
significant, so have kept it out of the TAFs. Any fog will mix
out quickly after sunrise. Smoke aloft from upstream fires has
temporarily cleared. The latest HRRR keeps the smoke out for now.
Otherwise, a very dry environmental sounding should not support
any clouds except for possibly some high based afternoon cumulus
as was the case Sunday.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...T
SHORT TERM...T
LONG TERM...T
AVIATION...Skipper
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Area Forecast Discussion
National Weather Service Morristown TN
911 PM EDT Sun May 21 2023
...New UPDATE...
.UPDATE...
Issued at 908 PM EDT Sun May 21 2023
Still an isolated shower or two across SW NC, and these should
dissipate later this evening. The forecast generally looks to be
in decent shape, with clouds expected to increase from S to N
overnight. Will tweak temps and dew points with this update.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 306 PM EDT Sun May 21 2023
Key Message:
1. Slight chance for an afternoon shower or thunderstorm possible
Monday afternoon in the southern Tennessee valley.
Discussion:
What a nice day! Went outside to take a few looks, and yes skies are
still hazy and not as blue as they should be for such a clear day.
Only clouds currently are building along the mountains, which we
cannot see from our office due to said haze. Haze is due to the
ongoing Alberta Canada fires, which have continued to send massive
plumes of smoke into the US. Fortunately the smoke will remain
elevated, and should not pose an air quality issue. High clouds
from a southern system will stream in overnight and lead to mostly
cloudy skies by sunrise for the southern two thirds of the
valley. Best chance for some patchy fog overnight will be the Tri
Cities area and north where clearer skies will remain and winds
will drop to calm for a longer period of time overnight.
Tomorrow
Dry weather will continue until tomorrow afternoon, when a few
people will win the lottery for some rain. A weak 500 mb shortwave
will be passing south of Tennessee. With just enough forcing from
the shortwave, we could see an isolated shower/thunderstorm or
two Monday afternoon into early evening before dissipation as the
day loses its heat. HRRR was the most aggressive out of both CAMs
and the global models with coverage. CAPE values are only around
300 or so, so not expecting any significant fireworks.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 306 PM EDT Sun May 21 2023
Key Messages:
1. Near normal temps through the extended.
2. Mostly dry for the long term forecast, with a few scattered
chances for precip.
Discussion:
Extended forecast is pretty benign overall. Tuesday will be dry for
the majority of the area, with some slight chances for diurnally
driven afternoon showers and possibly a few rumbles of thunder in
the southern valley and higher terrain.
Northeasterly/easterly 850 flow on Wednesday could produce some
downsloping wind that could lead to a dip in Td and subsequent RH
values Wednesday afternoon in the Valley. A low over southern
Ontario will dig an upper trough south over the southern
Appalachians towards the middle and end of the week. As this trough
dips into the mid-Atlantic and southern appalachians, it pushes a
cold front to approach TN from the north on Thursday, leading to a
slight uptick in PoPs in northeast TN and the East TN mountains.
Confidence in the synoptic setup remains iffy, this leans us towards
an omega block pattern for the weekend with ridging over the central
US and a trough over both the east and west coast.
&&
.AVIATION...
(00Z TAFS)
Issued at 637 PM EDT Sun May 21 2023
Clouds will increase, and there is a very low chance of a shower
during the day at CHA but probability is too low to include for
now. VFR conditions are expected for the period all sites. Winds
will generally be light.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 60 82 61 81 / 0 30 20 20
Knoxville McGhee Tyson Airport, TN 56 82 59 81 / 0 10 10 10
Oak Ridge, TN 56 83 60 81 / 0 10 0 10
Tri Cities Airport, TN 50 80 56 78 / 0 0 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...Wellington
LONG TERM....BW
AVIATION...
Area Forecast Discussion
National Weather Service Mount Holly NJ
848 PM EDT Sun May 21 2023
.SYNOPSIS...
Canadian high pressure will build southward down the East Coast
through Tuesday, resulting in mainly quiet weather. A cold front
will push in from the northwest late Wednesday, followed by
another area of high pressure and a somewhat cooler and drier
airmass for Thursday and Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
High pressure continues to build over the region with deep
subsidence evident on the WV satellite. Some persistent strato-
cumulus developed late Sunday morning through the afternoon,
resulting in more clouds than sun for much of our region. The
old CU- rule (model low- level moisture/stability parameter)
highlighted these clouds fairly well based on RAP guidance.
With the loss of daytime heating, increased stability and
lowering mixing heights, skies are clearing and northwest
breezes have relaxed. Expect winds to become calm overnight
with lows dropping into the mid to low 50s.
Fair weather continues for Monday as high pressure sits over the
region. Ye olde `cu rule`, along with forecast soundings and
modeled sky cover suggest that cumulus and stratocumulus will
once again develop midday Monday and possibly last through the
evening, particularly northwest of I-95. There is a 15 to 30
percent chance for showers and even a slight chance for a
thunderstorm around the Poconos Monday afternoon as a cold front
moves south. Would not rule out spotty showers as far south as
the Lehigh Valley and into parts of northern NJ as well. Any
showers that develop are not anticipated to impact central,
southern NJ, SEPA, or DelMarVa. Highs tomorrow are expected to
be in the mid to upper 70s. However, areas closer to the coast
will stay in the 60s with a notable onshore breeze.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
High pressure over New England Monday night will drift offshore
by Wednesday morning. This set up will bring mainly clear skies
with continuing onshore winds. An upper level trough and
associated surface cold front will pass through upstate New York
Wednesday and through our region Wednesday night. This will result
in widely scattered showers and thunderstorms mainly for areas
north of the urban corridor Wednesday evening.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Following the frontal passage, Thursday and Friday should
feature sunshine with seasonable temperatures dominated by
surface high pressure. Models continue to suggest an upper
level low will form over the northeastern United States Friday
and remain over the area through Sunday. Meanwhile, rain
associated with a system in the southeastern United States may
become absorbed by the upper low, bringing clouds and rain
northward for the first half of the holiday weekend. It is still
uncertain if much of the rain moving northward will remain
offshore or will impact areas further inland.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight (00Z through 12Z)...VFR/SKC. NW to N winds gusting to 18
kt in some spots until 00-02Z, but otherwise becoming 5 kt or
less overnight, and tending to veer to NE. High confidence.
Outlook...
Monday...VFR. Some 040-080 ceilings develop in the afternoon
mainly NW of I-95, with some brief showers possible from about
ABE northward. East to northeast winds 4-8 kt, but 10-15 kt near
the coast.
Tuesday through Friday...VFR. Isolated showers late Wednesday
in the Poconos and Lehigh Valley into northwestern New Jersey.
&&
.MARINE...
Mainly southerly winds around 5 to 10 kt becoming light
northerly overnight. Sub-advisory conditions as seas have
continued to drop off with a decaying easterly swell. Combined
seas mainly in the 2 to 4 ft range into Monday.
Outlook...
Monday through Tuesday...Winds increasing ENE 10-16 kt with
some gusts over 20 kt. Seas may build back to around 5 ft on
Tuesday, particularly offshore, which may require a Small Craft
Advisory.
Wednesday...Winds veer to SE around 10 kt as a cold front
approaches Wednesday night. Seas 2 to 4 ft.
Thursday and Friday...North to Northeast winds 10-20 kt with
gusts possibly around 25 kt at times, and Small Craft Advisories
may be needed. Seas 4 to 6 ft.
Rip Currents...
There is a LOW risk for the development of dangerous and life
threatening rip currents for Delaware and New Jersey beaches on
Monday. The risk increases to MODERATE on Tuesday for New Jersey
beaches.
Winds will be from the northeast at 10 to 15 mph on Monday.
Breaking waves are expected to be around 1-2 feet with a medium
period easterly swell.
Winds on Tuesday become more easterly and remain around 10 to
15 mph. Breaking waves are expected to increase to be around
2-3 feet, particularly along the coast of New Jersey. A medium
period easterly swell remains as well.
Please keep in mind that lifeguards may not be on duty, and
ocean temperatures are still quite chilly, mainly in the lower
60s. This makes it especially dangerous to enter the surf.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
SYNOPSIS...Deal/Fitzsimmons
NEAR TERM...Dodd/Deal/MPS
SHORT TERM...Fitzsimmons/Franklin
LONG TERM...Fitzsimmons/Franklin
AVIATION...Dodd/Deal/Fitzsimmons/Franklin/MPS
MARINE...AKL/Deal/Fitzsimmons/Franklin/MPS