Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/19/21
Area Forecast Discussion
National Weather Service Amarillo TX
1040 PM CDT Sun Jul 18 2021
.AVIATION...06Z TAF...
VFR conditions expected through 18Z with the exception of KGUY
which could see some IFR to LIFR conditions for an hour or two,
mainly around sunrise. Some low clouds, fog, or mist may develop
during the peak cooling time around 12Z. Thunderstorms are not
quite done in the area mainly for KAMA. However, prevailing
impacts are not expected and have left thunder out of the TAF for
now. Once 18Z comes around thunderstorms will once again be a
possible threat to VFR conditions. For now have PROB30 groups for
KDHT and KAMA.
Hoffeditz
&&
.PREV DISCUSSION... /Issued 607 PM CDT Sun Jul 18 2021/
AVIATION...00Z TAFs...
Summer thunderstorms will continue to threaten the combined
Panhandles this evening and in to the overnight hours. Categorical
degradation will be possible if a terminal is directly impacted
by a storm. KDHT will be next in line to be impacted by at least
VCTS in the first 2 hours or so of the 00Z TAF period. KAMA will
have a better chance for TS impacts after 03Z. Have kept TAFs as
optimistic as possible right now, but amendments may be needed at
times. Wind gusts up to 40 kts and torrential downpours will be
possible with thunderstorms. VFR conditions with light southerly
winds will be prevalent outside of thunderstorms.
Hoffeditz
PREV DISCUSSION... /Issued 244 PM CDT Sun Jul 18 2021/
SHORT TERM (Today through tomorrow night)...
Overview:
Somewhat tricky forecast today as we start shifting away from the
northwest flow aloft, yet continue to have the tropical airmass in
place across the Panhandles. It doesn`t take much with this type
of airmass to get convection going, but we have signals that could
inhibit thunderstorms today. With that said, any thunderstorms
that happen to develop could become strong to severe, especially
central and eastern parts of the combined Panhandles. Main
threats for any thunderstorms will be localized flooding,
lightning, and damaging wind gusts.
Further Details:
H5 center of high pressure residing over the Four Corners region
will slowly push northward today. By 00Z (7pm), the center could
be over eastern parts of the Great Basin. During this transition,
we are going to go from the northwest flow we have been
experiencing for several days to a more northerly flow. We still
have the tropical airmass in place across the area, but the
northerly flow pattern isn`t the best for convection. That said,
we have a convective complex pushing in from Nebraska and western
parts of Kansas. As of 2pm, a noticeable outflow boundary is
heading our way ahead of the complex, and could reach the Oklahoma
Panhandle by 3-4pm as storms are already starting to fire up. If
this trend continues, we could have thunderstorm activity through
about midnight. We need this boundary as we are lacking energy
aloft. In fact, forecast soundings from the HRRR and RAP indicate
subsidence aloft as seen from an elevated mix layer (EML) around
500mb-400mb. This EML will inhibit storms, but with the boundary
pushing in and some subtle semblance of energy aloft, this could
help initiate storms this afternoon and evening. If the convective
complex doesn`t make it this far south, we may end up dry across
most of the area besides maybe a few pop-up thunderstorms from
convective temperatures. Also, hodographs are small and there
isn`t much shear, so widespread severe weather is unlikely
today/tonight even with the outflow boundary from the complex.
Localized flooding, lightning, and isolated damaging wind gusts
will be the main threats. Weak lapse rates are not allowing for
much instability, but there could be enough MLCAPE to trigger a
couple rogue storms producing hail around an inch in diameter.
For tomorrow, its another one of the situations where today`s
convection--or lack thereof--will impact our thunderstorm
potential for tomorrow. Currently thinking if the outflow
boundary doesn`t make it into our area today/tonight, it may make
an entrance tomorrow morning and afternoon, increasing our threat
for thunderstorms during this time. For now, we will have to wait
and see what happens today, but any storms that form tomorrow
could become strong to perhaps severe with similar threats as
today. Only change with tomorrow is the lapse rates are steeper,
so we could have a greater threat for large hail tomorrow.
Guerrero
LONG TERM...Tuesday through Saturday...
Cooler temperatures are expected through the beginning of the
long term period before temperatures rise back to near normal for
this time of year. After Tuesday morning, drier conditions will
hold through Saturday.
A H500 ridge will extend across the central CONUS on Tuesday,
with the center of high pressure located near the four corners
region. The NBM is suggesting a stray shower or storm may remain
in the far southwestern Texas Panhandle after 12z on Tuesday.
However, latest guidance has most of this activity south of the
CWA, so have reduced POPs across the southwest after 12z.
Otherwise, the cooler than normal pattern continues through
Wednesday, as the main axis of the upper level ridge remains off
to the west.
Looking towards Thursday and beyond, the ridge will begin to
slowly drift towards the east. A weak low pressure system with
associated trough attempts to undercut the ridge across central
and west Texas. With the upper level high pressure centered over
the central Rockies near Colorado and a possible weak upper level
center of low pressure to our south, northeasterly to easterly
flow aloft is expected. This type of flow is not favorable for
precipitation, so drier and warmer conditions are expected through
the rest of the extended.
Muscha/Ward
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
36/89
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Sun Jul 18 2021
.UPDATE...
Issued at 956 PM CDT Sun Jul 18 2021
Quiet weather continues over most locations, but the chance for a
few isolated storms continues, mainly over western locations.
Right now one is located just to the west of the border near
Wibaux, but previously a few were located to the east. Still do
not expect severe weather with these storms.
UPDATE Issued at 630 PM CDT Sun Jul 18 2021
Isolated thunderstorms have developed over western portions of the
area, but these have remained tame. Expect this trend to continue
as the evening goes on. Going forecast remains in good shape, with
minimal changes needed.
&&
.SHORT TERM...(This evening through Monday)
Issued at 1239 PM CDT Sun Jul 18 2021
Hot and hazy conditions highlight the short term forecast period.
Currently, surface low pressure was situated over eastern Montana,
with a weak defined surface trough into southwest Manitoba. Aloft,
the latest water vapor imagery shows a weak impulse over eastern
Montana heading toward the North Dakota border, but you can also
see the building ridge of high pressure over the Northern Rockies
and into the Northern Plains. SPC mesoanalysis page shows
1500-2500 g/kg MLCape over most of western and central North
Dakota, but also with a good amount of Inhibition. Latest NUCaps
sounding from near Minot shows around 800 g/kg MLCape with a CIN
around 115, or roughly twice that of the RAP analysis. The
strongest low level moisture convergence remains north of the
border and the weak impulse over eastern Montana will be working
through a building ridge. We have therefore trimmed back our pops
for late this afternoon and this evening. A few of the normally
over zealous CAMS still do indicate some convection developing
over or moving into western ND late this afternoon/early this
evening, but even this is relatively tempered. The latest few runs
of the RAP/HRRR have been completely dry. We will keep a mention
of an isolated storm in the far west late this afternoon, then
mainly far west and north central this evening. Earlier depiction
of Canadian convection dropping south into our eastern CWA late
tonight has also backed off and shifted more north and east, just
clipping northeast ND. Can`t completely discount something around
the Turtle Mountains, but our given guidance has this area dry
now, and with the current trends, will leave it dry. It will be
another warm night, with lows mainly in the mid and upper 60s.
As was mentioned in the previous discussion, Monday is now
looking to be the hottest day of the week as the upper ridge
surges into eastern Montana and far western North Dakota. With 850
MB temperatures around 30C into western ND and mid and upper 20s
as far east as the Highway 83 corridor. Temperatures of 100-105
are possible across western ND with temperatures around 100
possible across central ND. There is a frontal boundary over
southern Canada that tries to sneak south into north central and
northeast ND, keeping temperature in the upper 80s around the
Turtle Mountains. This boundary will be a focus for isolated
afternoon and evening thunderstorms Monday, with areas south of
here remaining too stable for thunderstorms.
Two concerns on Monday are fire weather issues west and the
potential for a head advisory west and central. The overnight
shift mentioned near critical fire weather conditions west on
Monday and Tuesday. Afternoon dewpoints drop down to around 15
percent in the far west central and southwest, but the winds look
to be rather light, even a bit lighter than what was though on
previous shifts. We do mix out nicely in the west but winds are
strongest near the surface and weaken and shift from south to
north as you go up and you`ll need to get above around 600 MB to
get some stronger winds above 20 knots to work down to the
surface. Will keep the mention of near critical and let the
evening and overnight shifts take another look. If we could get
some stronger winds to mix down for a sufficient amount of time, a
Red Flag warning would probably be needed given the hot
temperatures, low humidities and drying vegetation.
As for possible heat headlines, will also let the evening and mid
shift take a look. Max apparent temperatures do reach as high as
103 in a few spots for a brief period Monday afternoon, roughly
along the Missouri River Valley. Afternoon dewpoints are around
5-10 degrees lower than today, and maybe even more southwest, so
there remains enough uncertainty with the actual values and the
areal extent and duration, to let the later shifts take another
look. Either way, it will be hot Monday and we continue to
advertise this via social media.
.LONG TERM...(Monday night through Sunday)
Issued at 1239 PM CDT Sun Jul 18 2021
Hot temperatures and periodic thunderstorm chances highlight the
long term forecast period.
After Monday, deep upper level low pressure spinning off the
Pacific Northwest coast through mid-week, will eject multiple
embedded waves eastward, then lifts east-northeast across
southeastern and central Canada Thursday through Saturday. The
embedded waves will effectively weaken the ridge over time, and
will also bring periodic chances for thunderstorms to the Northern
Plains during the work week. Lots of uncertainty with these
smaller scale features more than 24 hours out regarding
precipitation chances. While temperatures will cool a bit as mid
level heights slightly fall, still very warm through Friday with
highs in the 90s along with a few locations seeing 100 as well.
We do see stronger winds on Tuesday, but temperatures and
humidities may also not be as high. Will keep the Near Critical
mention for fire weather conditions in the west again Tuesday.
Also not sure about the impact from an increase in smoke aloft
from the wildfires to our west and north will have on daytime
highs next week. Local research indicates higher levels of smoke
aloft can significantly reduce daytime temperatures. Looking at
the latest HRRR and Canadian smoke models, we don`t necessarily
see a continuous stream of high amounts of smoke aloft, but our
synoptic setup is one which we don`t see the continuous high
amounts of smoke, but occasional shots, and the smoke keeps re-
circulating around and around the northern plains. Not sure if
this will have a huge affect on daytime high temperatures, but it
certainly won`t help make it warmer.
Height falls across the Northern Plains will be much more
noticeable late in the week/next weekend, with NBM daytime high
temperatures more in the mid 80s to lower 90s next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM CDT Sun Jul 18 2021
Isolated thunderstorms this evening western North Dakota, possibly
spreading northeast as the evening goes on. Have mentioned a VCTS
in the KDIK TAF as a few storms have developed near that area.
Did not mention in other TAFs as confidence remains quite low.
Otherwise, VFR conditions will prevail.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...JJS
Area Forecast Discussion
National Weather Service Dodge City KS
647 PM CDT Sun Jul 18 2021
...updated aviation section...
.SHORT TERM...(This evening through Monday)
Issued at 235 PM CDT Sun Jul 18 2021
A chance of thunderstorms will continue this afternoon as an MCS
moves through the area. Precipitation chances will then be
confined to central Kansas overnight with partly cloudy skies
elsewhere. Any thunderstorms that do develop across central Kansas
should move out of the area by tomorrow afternoon with decreasing
cloudiness. Winds will generally be light and form the southeast
through tomorrow with the exception of when thunderstorms move
through. As for temperatures, lows tonight look to dip into the
mid 60s with highs tomorrow in the mid to upper 80s.
.LONG TERM...(Monday night through Sunday)
Issued at 235 PM CDT Sun Jul 18 2021
Dry conditions are expected through the majority of the long term
forecast as an upper level high slides east and over the Plains
with high pressure being the dominate feature at the surface. A
few models suggest a slight chance of precipitation as we head
into the weekend but this is many days out and will need to be
monitored through future model runs. As for temperatures, highs
will start out in the upper 80s Tuesday with 90s expected through
the remainder of the long term forecast. Lows will generally be in
the 60s with a few low 70s entering central Kansas mid to late
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 646 PM CDT Sun Jul 18 2021
A severe MCS has exited the area into western Oklahoma, while
leftover stratiform precipitation from decaying convection continues
over the far southwest counties. Based on most recent convective
allowing models and latest mesoscale trends, we`ll discount the NSSL
WRF`s overnight and monday convection as the HRRR took the MCS much
farther east than did the aforementioned model. Therefore a light
easterly surface wind and overall clear/VFR category forecast for
the local terminals. Given the additional earlier rains and upslope
flow Tonight, there might be some favored area of ground fog
development, but not enough confidence exists to support adding to
any terminals at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 66 86 63 87 / 0 10 10 0
GCK 64 85 62 86 / 0 10 10 0
EHA 64 88 63 86 / 80 20 10 0
LBL 65 86 63 85 / 10 20 10 0
HYS 66 86 61 88 / 0 10 10 0
P28 68 88 63 89 / 0 20 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Hovorka_42
LONG TERM...Hovorka_42
AVIATION...Russell
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
956 PM CDT Sun Jul 18 2021
...Short Term Update...
.UPDATE...
Issued at 956 PM CDT Sun Jul 18 2021
- Follow-up to earlier comments about overnight fog potential:
Although still do not think truly widespread dense/impactful fog
is likely for the Monday AM commute, have changed course a bit
from last discussion a few hours ago and opted to blanket the
entire CWA with generic "patchy fog" wording for the majority of
the 4-10 AM time frame on latest update. For one thing, last few
HRRR visibility runs are now starting to hint more at at least
limited fog potential especially in our far eastern zones.
Secondly, have some concern that models may be under-doing the
contribution to boundary layer moisture/RH from the decent
coverage of generally 0.25-1.50" (localized higher) rain that fell
across much of our southwest 1/2 this morning. Last but not
least, we admittedly got caught off guard a little bit this
morning with at least brief dense fog in parts of the area
(including the Tri Cities) and would rather at least get basic fog
potential into the forecast this time around (especially for a
weekday morning/commute). While patchy/limited dense cannot be
ruled out, will defer to incoming night shift to better pinpoint
any areas where the "fog throttle" might need to be hit a little
harder, but for now at least the basic fog potential is in there.
UPDATE Issued at 809 PM CDT Sun Jul 18 2021
Some comments solely focused on the next 12-16 hours (through
mid-late morning Monday), largely echoing the same sentiments as
preceding day shifter discussion...
- Rain/thunderstorm chances:
The main forecast change/update so far this evening was to delay
the onset of low-end thunderstorm chances/PoPs until the post-
midnight hours, but still keeping them focused mainly within the
southwestern 1/3 or so of the CWA (mainly SW of a Kearney-Osborne
line). Honestly, did consider removing all mentionable chances
completely based on the consensus of most of the latest model data
(including past several HRRR runs) and just going with "silent
Pops" (less than 15 percent) in official products. However,
considering that earlier model runs today (including 12Z HRRR/HRW
NSSL/HRW ARW and even the ECMWF) suggested that at least spotty
activity could flare up mainly sometime between 2am-sunrise, not
to mention the fact that convective coverage has "overachieved"
the past couple of mornings in terms of likelihood/coverage, felt
it would be prudent to hang onto some smallish 20-30 PoPs for now.
For sure though, support for early Monday morning convection does
NOT look as favorable as it did for Sunday morning, as for one
thing, the presence of any subtle mid level disturbance and
resultant narrow corridor of low-mid level moistening/convergence
diving down from the north looks even more nebulous and/or non-
existent this time around. That being said, IF any convection does
form (again a huge "if"), it could persist for at least a few
hours past sunrise as it gradually departs to the south-
southwest, so hung onto 20 Pops through mid-late morning for our
extreme southwest CWA. Last but not least, even IF convection does
manage to form early Monday morning in our west-southwest zones,
odds strongly favor it being non-severe given fairly weak
instability (generally no more than several hundred J/KG of
elevated CAPE) and only modest deep-layer shear around 25-30KT).
&&
.DISCUSSION...(This evening through Sunday)
Issued at 301 PM CDT Sun Jul 18 2021
Convection this morning has pushed south of the local area, and as
skies cleared this afternoon, a bit of cumulus has filled in
across the local area. Expect this cloud cover to thin by early
evening...with another potential round of thunderstorms possible
late tonight through early Monday morning.
Overall...the confidence for storms tonight has decreased a bit
with the latest runs of the HRRR/RAP/NAM all coming in mostly dry
overnight...but previous runs hinting at some isolated convection
mainly west of Highway 281 late tonight through early Monday
morning where there is forecast to be an area of weak convergence
and potentially another weak upper wave to help spark convection.
Despite the trends of latest models towards less activity...wanted
to keep in some isolated convection based on what has occurred
the past few nights along with the subtle hints for something
forming after midnight. That said...anything that does form is not
expected to be severe and continued with non-severe thunderstorm
wording in the HWO. The other concern overnight was the potential
for fog...which we saw across much of the local area this morning.
With elevated dew points and light winds with a southeasterly
component...this is not completely out of the question...although
downplayed the potential due to low probs in the SREF guidance and
no indication across our local area in the HRRR...although this
potential may need to be revisited later this evening.
As we then transition into the work week, warmer and drier weather
appears to be in store for the local area as the upper level ridge
to our west begins to tilt and transition eastward. This should
shift storm chances away from the local area and result in a
gradual warming trend as heights aloft build across the local
area. While there could be a few weak disturbances brush the
fringes of the local area late in the period...confidence of
timing and location is low...and opted to remove the small pops
that were given by the blend of models this afternoon...keeping
conditions dry through the end of the work week and into next
weekend. As we dry out...also expect temperatures to rise...with
highs climbing well above normal towards the end of the work
week...with some models hinting at highs near 100 with the
potential for heat index values climbing above 100. In
fact...looking at some of the long range guidance...this could be
the beginning of a prolonged warm stretch across the local area,
which we will continue to monitor as it unfolds.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 809 PM CDT Sun Jul 18 2021
Ceiling/visibility/precipitation:
Have maintained a VFR ceiling/visibility forecast, and with at
least medium-high confidence that this should verify through the
vast majority of the period. However, cannot rule out at least a
brief period of sub-VFR conditions regarding both elements: 1) For
ceiling: time-height relative humidity progs clearly show that a
low-end VFR ceiling is quite possible at times later tonight into
part of Monday daytime, and it wouldn`t take much for any ceiling
to at least briefly dip into MVFR territory...2) For visibility:
Although not currently expecting a repeat of the dense fog issues
that briefly impacted both KGRI/KEAR this morning, at least a
little haze/light fog seems plausible a few hours either side of
sunrise. As a result, have introduced a low-end VFR "6SM BR" to
the TAFS 09-15Z to hint that VFR visibility may not be a slam
dunk. Precipitation-wise, although there is still a very small
chance of showers/weak storms perhaps affecting especially KEAR
within a few hours either side of sunrise, this chance is now
considered so low that even a basic "vicinity"/VCTS can no longer
be justified and has been removed.
Winds:
Another low-impact period here, as sustained speeds should average
under 10KT throughout, with direction prevailing somewhere between
easterly and southerly (in other words, generally southeasterly).
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Pfannkuch
DISCUSSION...Rossi
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Lake Charles LA
945 PM CDT Sun Jul 18 2021
.UPDATE...
Evening update.
&&
.DISCUSSION...
Showers and thunderstorms have dissipated over the area. Skies
will be partly cloudy to mostly clear overnight. A few nocturnal
showers and thunderstorms could develop along the coast into the
early morning hours. However, chances will be low. Chances will
increase after the sun rises. The 00Z HRRR is indicating a
possible convective system making its way into our area from the
north late Monday into Tuesday. There does appear to be model
consensus regarding this, as the GFS and NAM are indicating
significant development in this timeframe as well. Thunderstorms
will be expected Monday into Tuesday as an upper-level trough
continues to dig south into our area. This aligns with the current
forecast, therefore no changes were made.
55
&&
.PREV DISCUSSION... /issued 647 PM CDT Sun Jul 18 2021/
DISCUSSION...
19/00Z TAF Issuance.
AVIATION...
Widely sctd aftn SHRA/TSRA are ongoing at this time, and
AEX/LFT/ARA could see brief impacts from SH or TS over the next
hour or two before convection finally dissipates with loss of
daytime heat. Conditions are currently VFR with a mix of SCT
CU/CB/CI per recent vis satellite. VFR expected to prevail
overnight with lower clouds diminishing. Another day of active
weather is expected on Monday, with a little better coverage once
storms develop by mid to late morning. Not only is convection
expected along an inland-moving seabreeze boundary acrs southern
areas but also acrs cntl LA where outflow driven convection
(associated with a front north of the area) is expected to be
sliding southward. Locally reduced cigs/vsbys and gusty winds can
be expected with SHRA/TSRA, but otherwise expect VFR conditions
amid SCT-BKN cloud cover. Winds will be light and vrbl, bcmg
southwesterly during the day Monday.
24
PREV DISCUSSION... /issued 252 PM CDT Sun Jul 18 2021/
SHORT TERM [Today through Tuesday Night]...The overall pattern
across the Conus has not changed much over the past week with a
large upper ridge out west and an upper trough located over the
east half. The only change lately is the pattern has been getting
slightly more amplified today and this will continue into early
this week. As the ridge builds in the west and the trough digs
south across the east, a cold front will advance into the deep
south. Ahead of the boundary moisture will pool which will
increase rain chances Monday. This front is expected to stall
across the East Texas Lakes Region and CenLA by Tuesday/early
Wednesday while the base of the upper trough cuts off. Widespread
rain and storms can be expected Monday evening through Tuesday as
the front moves in and the forming upper low moves over the region.
05
LONG TERM [Wednesday through Sunday]...
By Wednesday, an extension of the E CONUS trough aloft is stretched
towards the Southern Plains, cutting off over the Gulf states and
retrograding westward. At the surface, a weak frontal boundary is
progged to stall just north of the forecast area and begin to wash
out. Airmass south of the boundary will remain quite moist with
PWATS around 2.00", so combined with the aforementioned forecast
elements, PoPs remain quite elevated to start the long term. While
activity will be diurnally enhanced, the upper level weakness will
allow PoPs to remain Wednesday night into Thursday, before once
again becoming fairly high through Thursday afternoon.
Forecast diverges a bit on Friday with GFS/ECMWF handling the upper
low differently. GFS continues retrograding the ULL into W TX while
the ECMWF slowly nudges it eastward from the ArkLaTex towards the E
CONUS trough. As a result, ECMWF comes in a little wetter than the
GFS, but in both cases enough weakness/moisture to result in at
least diurnally enhanced PoPs. In the forecast, stuck with the NBM
which yielded higher than climo diurnal activity.
For some good news, there may finally be some signs of relief on the
horizon from the persistent wet pattern... By the weekend, ridging
slowly starts to increase leading to more convective suppression and
more typical low-end/isolated PoPs. While still some uncertainty,
could see this last into the following week as well. To that end,
the CPC 6-10 and 8-14 day outlook both indicate higher probabilities
(~40% chance) of conditions drier than climatological normals.
50
MARINE...The subtropical ridge will remain stretched from the
Atlantic into the northern gulf coast through the period. This
will keep a generally light and onshore flow in place through the
period. Gusty winds may occur in showers and storms that are
forecast through the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 76 90 72 88 / 30 80 80 70
LCH 77 91 74 88 / 10 80 90 90
LFT 76 90 74 87 / 20 90 90 90
BPT 76 92 73 88 / 10 60 90 90
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
615 PM CDT Sun Jul 18 2021
.SHORT TERM... (Through Late Monday Night)
Issued at 241 PM CDT Sun Jul 18 2021
Currently, the MCV responsible for last night`s rain is
approaching the confluence of the Mississippi and Ohio Rivers, and
the front from late last week is roughly along the Missouri-
Arkansas line. Isolated to scattered convection this afternoon
will be associated with the MCV and residual surface moisture
behind the front mainly across southeastern Missouri where SBCAPE
is around 1,500 J/kg per SPC mesoanalysis. A shortwave noted in
water vapor imagery over the Middle Mississippi Valley will
continue its southward movement, bringing the low chance for
isolated convection over our Illinois counties this afternoon.
Lapse rates remain very poor area wide, and there is a subtle warm
nose around 600 mb per RAP sounding analysis, so convection will
be limited to mostly showers, though I can`t rule out a rumble of
thunder. Convection will die off as instability wanes near sunset,
and tonight looks dry across the CWA.
Tomorrow, the shortwave will continue its path southward and phase
with another shortwave currently over the Plains. These upper-level
features and their associated upper-level support will be moving out
of the CWA during peak heating, limiting any convective potential to
far southwestern and southern portions of the CWA. Here, CAMs have
widely scattered convection where moisture is deeper and roughly
1,500 J/kg of MUCAPE is forecast, so I have enough confidence to
maintain a slight chance of isolated showers during peak heating in
this area. Lapse rates continue to look poor, and some model
soundings show a bit of a warm nose around 600 mb, so I expect
updrafts to remain weak, but I can`t rule out a shower or two
overachieving and producing a couple lightning strikes.
Elmore
.LONG TERM... (Tuesday through Next Sunday)
Issued at 241 PM CDT Sun Jul 18 2021
EXTENDED
Our relatively calm weather will continue through the first
portion of the extended period, as the CWA remains under
northwesterly flow aloft and a surface high sits over the Midwest.
On Wednesday, the ridge over the western U.S. will begin to build
eastward, and in response, the surface high will begin to shift
eastward as well. This eastward shift in the surface high will allow
for southerly low-level flow to return to the Middle Mississippi
Valley late Wednesday into Thursday, allowing for warm, moist air to
begin advecting into the CWA. This transition will be marked by
temperatures climbing above climatological normals through the end
of the extended period and a return of higher humidity.
Ensemble guidance still differs in the extent of eastward progress
the ridge makes later this week. More eastward movement would lead
to temperatures warming a couple of degrees more and a decrease in
rain chances, while a less eastward extent would lead to
temperatures not getting quite as warm and greater rain chances due
to shortwaves riding the eastern periphery of the ridge. Currently,
3 of the 4 ensemble clusters per WPC guidance support the second
solution to some degree, and the current forecast represents
somewhat of an upper-bounds to that solution. All that being said,
the end of this upcoming week and next weekend will still likely be
hot and humid - a notable difference from this current weekend.
Elmore
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 615 PM CDT Sun Jul 18 2021
VFR conditions are expected through much of the period at all
terminals. The exception to this will be at COU and JEF where a
brief period of MVFR stratus is expected early Monday morning.
Confidence in the MVFR stratus materializing has decreased some
from the previous forecast, but will maintain it for now and will
re-evaluate with the 06Z issuance. Otherwise, VFR conditions are
expected at all sites through the period. Cannot rule out some
light fog at KSUS Monday morning or even a light shower at any
site tonight, but these threats are too low to include any mention
at this time.
Deitsch
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
739 PM EDT Sun Jul 18 2021
.SHORT TERM...(This evening through Monday)
Issued at 340 PM EDT SUN JUL 18 2021
Widespread smoke associated with the wildfires in Ontario and
Manitoba has been the most exciting thing over our region today.
This is producing haze over much of the region. So far
observation sites haven`t registered any visibility reductions, so
its been hard to say how much dinural mixing may be creating some
smokey smells at the surface. HRRR Smoke product continues to
suggest some smoke could mix down this afternoon, mainly in the
interior west. Daytime highs so far have climbed into the 80s for
most. The exceptions are along Lake Superior, mainly east of
Marquette and up in the northern tip of the Keweenaw. Given the lake
breeze off Superior didn`t result in much of a temperature change, I
expect even the lakeside communities could experience rising
temperatures for the next few hours.
The reason today has been warm and relatively uneventful is a
surface high positioned over Lake Michigan/Wisconsin and upper
level ridge emanating out Rockies extending into Ontario/Quebec. As
we move through tonight and into tomorrow, expect the
high to sink south as a cold front approaches the region late
tomorrow evening. Light gradient flow in the eastern UP will allow
for lake breezes to push well inland. MLCAPE looks to climb to
near 1000 j/kg near the boundary, which would be enough for
shower and thunderstorms to pop up, mainly in Delta and
Schoolcraft. Shear looks weak so strong to severe storms are not
expected at this time.
Southwest winds over the western parts of Lake Superior and in the
Keweenaw are expected to increase soon after sunrise tomorrow. Some
models suggest 925 mb winds could approach 25 to 30mph in some
places. Given mixing during the day tomorrow, the Keweenaw may have
some gusty winds reach the surface. Its also going to be warm
tomorrow. I`m a little uncertain how much shortwave radiation will
be prevented from warming the lower atmosphere due to the continued
smoke aloft, but generally upper 80s with some low 90s are possible,
particularly away from the lakeshores. Coupled with the dry airmass
and the lack of rain in recent memory, some elevated fire weather
conditions may be possible from northern Houghton County northward.
.LONG TERM...(Monday night through Sunday)
Issued at 357 PM EDT SUN JUL 18 2021
The overall large-scale pattern for next week will feature
anomalously strong ridging centered over the Rockies and downstream
troughing into eastern Canada and the northeast U.S. The Upper Great
Lakes will remain on the northeastern edge of the ridge beneath
persistent NW flow aloft between these large scale features. A few
waves digging southeastward through the flow this week will lead to
lowering heights and temps cooling into midweek behind Mon night`s
cold fropa, but then it appears ridging and warmer temps will tend
to dominate late week.
Monday night, a strong cold front will be approaching our area from
the north. With the models trending slower with the fropa and given
that dewpoints Monday afternoon will likely mix out ahead of the
front, it would appear instability may be limited for thunderstorms.
Even the previously more bullish moisture-biased NAM soundings now
show very limited instability even for showers, let alone
thunderstorms Mon night. Suspect more isolated to scattered coverage
of showers along the front and will trend PoPs accordingly.
Tuesday, behind the front, cloud cover may be slow to clear in the
morning. Many models hold on to low stratus in the typical north
wind upslope areas in Marquette County. This cloud cover along with
a steady north wind and 850 mb temps dropping to around 10-12 C
behind the front should hold temps down in the mid 60s to low 70s
for highs. Could even see temps struggle to get out of the low 60s
for highs in parts of Marquette County if cloud cover hangs on
longer than models suggest - which it often does under northerly
winds.
Still a decent amount of uncertainty with regards to temps on
Wednesday, although other than the 12Z NAM, models generally have
trended cooler for Wednesday. So, did follow the lead of mid shift
and lowered max temps a bit blo NBM guidance...generally in the
lower to mid 70s. The 12Z NAM also indicates quicker advancement of
the warm front and associated light rain into the area on Wednesday,
but this solution too seems to be an outlier compared to the drier
GFS and Canadian solutions.
Looks like the next best chance of rain will be Wednesday night when
the next shortwave drops down in the NW flow aloft and its
associated surface cold front drop southeastward across the Upper
Great Lakes. The 12Z GFS and Canadian and 00Z EMCWF show a distinct
precip signal late Wednesday night. Therefore, will maintain the
likely PoPs for Wednesday night. Similar to Monday night,
thunderstorm chances may be limited by questionable moisture return
and instability ahead of the wave. However, models do show stronger
shear with this wave, which could perhaps end up bolstering
thunderstorm chances. Showers and a few storms will probably linger
into Thursday as the frontal boundary continues to sag through the
area.
By the end of the week, the warm Western CONUS ridge starts to nose
into the area, leading to another warm-up. Although there is still
some spread in the ensemble guidance, the lion`s share of members
take 850 mb temps back up into the 15-18 C range which means more
highs in the 80s for most of the area Friday into the weekend.
12Z operational models do hint at a few ridge-runner shortwaves
moving through the Upper Lakes which could maybe produce a few
rounds of convection over the area next weekend, so this will be
something to watch on subsequent model runs.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 739 PM EDT SUN JUL 18 2021
VFR conditions will prevail at all sites as the region remains under
the influence of high pressure and a dry airmass. Winds will
increase at KCMX ahead of an approaching cold front.
A fairly thick layer of smoke associated with wildfires upstream is
expected to remain over the region through this period. However,
vsby is expected to remain VFR with only a low probability of brief
MVFR conditions.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 340 PM EDT SUN JUL 18 2021
Light winds are expected to continue tonight across the lake as
surface high continues to dominate the region. This high will sink
south tomorrow as a 925mb 25 to 30 knot LLJ moves into the western
part of the lake. I`m skeptical about how much of these
southwest winds will mix to the surface given the stable lower
atmosphere, but high reporting platforms could end up observing some
gustier conditions. Cold front will move through tomorrow night.
Thunderstorms will be possible ahead of and along this boundary.
Afterwards tomorrow night, north to northeast winds are expected to
be 20 to 25 knots. By late Tuesday, winds look to return to 20
knots or less across the lake and remain there through the rest
of the week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JP
LONG TERM...Voss
AVIATION...JLB
MARINE...JP
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 250 PM CDT Sun Jul 18 2021
From the comings and goings of co-workers, the undersized window
and ObsMonitor3.3.1, it seems like it`s a pleasant day outside.
Current temps show numbers within a couple of degrees on either
side of 80 and wind speeds running mostly under 10 knots out of
the southeast. The sun is being filtered out by two distinct cloud
decks... a broken set of cumulus at about 3000 feet caught up in
the low level SE winds and some stratus blowing off the top of the
convection in north central Kansas that`s working in the opposite
direction.
Some significant haze from western wildfire smoke across most of
Nebraska today, but generally west of this CWA. This gradient of
vertically integrated smoke will continue for Monday with bluest
skies east of the Missouri River. The 12Z run of the HRRR reveals
a denser plume of smoke pushing overhead on Tuesday afternoon.
Expect some patchy fog development overnight tonight as a nose of
surface high pressure helps bring the winds to a near standstill.
Best chances of this fog will be along the Kansas state line,
western Iowa, the easternmost tier of counties in the state of
Nebraska, and generally where there`s plenty of corn.
Monday morning convection has been progressively further west on
latest guidance and have removed isolated POPs as a result. This
makes the spotty heavy rain on Saturday all the more important as
the forecast will be dry through the work week... with only slight
chances of thundershowers Friday night and perhaps the weekend.
Under the 500HPa ridge, southerly winds will help temps slowly
rise over the course of the week. Tuesday will be relegated to
the mid-80s. Expect the entirety of the area to manage 90F+ by
Thursday with mid-90s to near 100F by Friday. Heat indices on
both Friday and Saturday may push 105 and trigger a heat advisory.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 601 PM CDT Sun Jul 18 2021
Light southeasterly winds are expected to prevail through the
forecast period. A diurnally driven cumulus field may also develop
by midday tomorrow and bring CIGs down to around 4 kft.
During the overnight hours, subsidence aloft should reinforce the
nocturnal BL inversion. This coupled with weak moisture advection
out of the southeast and radiational cooling will help bring the
boundary layer to near saturation by early morning. As such,
patchy fog is possible across parts of east central Nebraska and
west central Iowa. This may result in a brief period of MVFR
conditions tomorrow morning at KOMA, but should return to VFR by
a couple hours after sunrise.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Nicolaisen
AVIATION...Mead
Area Forecast Discussion
National Weather Service Spokane WA
428 PM PDT Sun Jul 18 2021
.SYNOPSIS...
Wildfire smoke will likely continue to plague the region with
areas of degraded air quality especially around the Methow Valley
and Lewiston area. There will be an increasing chance for
thunderstorms over the eastern third of Washington and North Idaho
Monday Night through Wednesday. Breezy and dry conditions next
week will also contribute to elevated fire concerns for ongoing
fires or any new ignitions that occur.
&&
.DISCUSSION...
...Critical Fire Weather Conditions possible Monday Night through
Wednesday...
Tonight through Wednesday: Models continue to show a broad
southwest flow over the region between a closed low off the
central BC coast and a ridge over the southwest US. Increased
monsoonal moisture and a pair of mid level waves tracking through
will provide two opportunities for thunderstorms over the eastern
third of Washington into the Idaho Panhandle...mainly east of a
line from Ritzville to Colville. The first wave arrives late
Monday Night into Tuesday morning. Several of the CAM`s models
show some elevated convection developing but lightning should be
isolated in coverage with 700-500mb MU CAPE of only 100-300 J/KG.
Still given the very dry fuels any lightning is a concern for new
fire starts. The second wave arrives Tuesday Night into Wednesday
morning. This one has a bit more instability to work with, and
stronger forcing as the upper low off the Central BC coast begins
to push inland. This raises concerns for more lightning with
scattered coverage possible over SE Washington into the ID
Panhandle. Despite the increased monsoon moisture, storms that
develop are expected to be elevated and fast moving, only putting
down brief rain. Thus new fire starts are a big concern and a
Fire Weather Watch has been issued from the Spokane area down to
the Palouse east into the Idaho Panhandle where confidence is
highest of thunderstorm development.
Besides thunderstorms starting new fires, also keeping a close eye
on winds and low relative humidity. A tight cross-Cascade pressure
gradient will promote breezy winds through the Cascade gaps Monday
evening. Tuesday gradients tighten a little further with breezy
winds expanding to include the Columbia Basin and Okanogan Valley.
Wednesday as the trough pushes in winds may increase a bit more.
Confidence is not high enough at this time of critical wind/rh
thresholds being met for a Fire Weather Watch, but conditions will
be elevated and could affect any new or existing fires.
Lastly, smoke will continue to impact air quality at times near
fires especially the Methow Valley and around Lewiston. Higher
level smoke from fires over Oregon will continue to track into
Eastern WA and North Idaho producing hazy skies. JW
Thursday through Saturday: After the cold front passage
Wednesday, a notably drier air mass with a dirty ridge moves into
the area. Minimum RH values will get down into the lower teens
with locally lower values, and combined with somewhat breezy
afternoons from diurnal mixing, fire concerns will stay elevated
Thursday and Friday. Temperatures Thursday will be slightly cooler
than Wednesday, only reaching the mid 80s for much of the area.
Things warm back up to the upper 80s and low 90s Friday. The rest
of the weekend, RH values are expected to increase slightly, with
temperatures remaining in the upper 80s and low 90s. RC
&&
.AVIATION...
00Z TAFS: High elevation smoke and haze will be found across the
northern mountains, Idaho Panhandle, and southeast Washington due
to ongoing fires. HRRR smoke models show this to persist through
the period. Areas of low level smoke may limit visibilities with
marginal VFR conditions near Lewiston as well as Winthrop under
light winds. Scattered high clouds start to move north Monday
morning. Some convection is possible across north central ID
Monday afternoon which could lead to occasional southeast gusts
to 15 mph near Lewiston and Pullman. rfox
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 97 66 91 61 88 / 0 0 10 20 20 20
Coeur d`Alene 65 96 64 90 59 87 / 0 0 10 20 20 30
Pullman 60 91 62 86 56 83 / 0 0 20 20 30 30
Lewiston 68 100 72 96 67 92 / 0 0 20 20 30 30
Colville 55 98 58 93 53 89 / 0 0 0 10 20 20
Sandpoint 55 94 62 88 58 86 / 0 0 10 20 20 30
Kellogg 59 93 67 86 64 86 / 0 10 10 20 30 30
Moses Lake 60 97 62 93 57 89 / 0 0 0 0 0 0
Wenatchee 66 97 67 91 62 87 / 0 0 0 0 0 0
Omak 66 100 66 96 61 91 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Fire Weather Watch from late Monday night through Wednesday
morning for Northern and Central Idaho Panhandle (Zone
101).
WA...Fire Weather Watch from late Monday night through Wednesday
morning for East Washington Palouse and Spokane Area (Zone
674).
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Sun Jul 18 2021
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Abundant monsoon moisture will continue to bring daily chances for
at least isolated to scattered showers and thunderstorms across
south-central and eastern Arizona with a tendency to favor the
higher terrain of eastern Arizona, especially for the first half of
the week. Isolated storms are also possible over southwest Arizona
and southeast California. Near to below normal highs expected for
the first half of the week, then below normal by late in the week.
More scattered to widespread storms are possible for the second half
of next week and into the weekend. Storms will be capable of
producing both locally heavy rain, strong winds, and blowing dust.
&&
.DISCUSSION...
The H5 RAP and SPC mesoscale analysis shows the UL high centered
near the NV-CO border, barely just N of 4-Corners area. Fairly deep
and moist S-SE-E flow aloft was present from below H7 to H5 to H3. A
large zone of elevated H7-H5 mean RH>=70 (& 80-90)% extended from N
MX, SE-S-Cent AZ into W-NW AZ. SPC mesoscale analysis showed
elevated PW ranging from 1.7-1.8 S and W of Phoenix to near 1.5
near Phoenix which was ~0.4 too low compared to the 12Z Phx
sounding which had over 1.85. The 12Z Phx sounding also showed
small caps in the mid levels and fcst sfc CAPE of 1389 j/kg. The
Phx 12Z also featured above normal mean W of 12.5 g/kg, up from 11.6
gm/kg shown on the 00Z sounding. SPC confirmed fairly widespread
elevated CAPE (& CIN) from the upper 100s to low thousands j/kg with
more elevated forecast values into the 2-3K j/kg forecast for the
afternoon along the outskirts and surrounding the CWA. 8 mid to late
morning ACARS showed mean MUCAPE up to 1276 j/kg.
Sunday GOES imagery showed abundant mid-upper blow-off clouds
associated with a weak PVA disturbance and and an area of associated
modest thundershowers SE of Phx earlier today. These thundershowers
moved into N Pinal and the SSE CWA including far SE Phx outskirts
this morning with spotty modest rainfall. By midday METSAT showed
cloudy-mostly cloudy conditions and an MCV in the W-central CWA and
W half of the Phx valley with an area of light rain returns, while
mostly clear skies, and stronger heating, dominated the E half of
Phoenix and much of the E CWA. The expanding UL ridge was driving
small disturbances and supporting the very moist and unstable
conditions across the high country, while igniting early afternoon
Mogollon Rim convection/thunderstorms.
The HREF and later runs of the HRRR support E AZ isolated to
occasionally scattered convection moving into S. Gila Cty for the
late afternoon and early evening for a few hours before decaying as
they edge west. Then a second late night round of convection is
depicted that could give Phx or the N-E Valley a glancing blow of
late night storms tonight. It is also very bullish on a very
pronounced E-NE outflow moving through Phoenix late tonight and even
possibly holding together through La Paz county early this morning.
For the first half of the week the UL high moves very little. As a
result very moist and unstable conditions and diurnal convection
will persist through the region, especially for the higher terrain
with its orographic and upslope advantages. As a result the
preferred NBM POPs remain significant through the period near 30-40%
around Phoenix with slightly lower POPs even supported out W across
SW AZ and SE CA. Storms will be capable of producing both locally
heavy rain, strong winds, and blowing dust.
Clusters and ensembles are still signaling possible upticks in
moisture for the second half of the week and into the weekend. This
may be the result of a larger easterly wave disturbance moving in
from Texas into N-NW MX. Higher end WPC QPF has emerged along with
increased chances for scattered flash flooding. Max temperatures
appear to become quite moderated in and around Phoenix as below
normal highs look to favor the upper 90s by late this week and
possibly even the weekend.
&&
.AVIATION...Updated at 2320Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds should become more solidly SW across the metro early this
evening with storms building over mountains. Although NBM shows 30%
chance of storms and HREF output indicates a 40% chance of outflow
winds in excess of 30 kt, in situ observations show an environment
not very good for thunderstorm maintenance. Recent HRRR model runs
have backed off the forecast of storms in the metro while also
dialing back outflows and wind speeds. Kept a mention of an outflow
boundary and VCSH in this TAF package, though with low confidence.
While stronger wind gusts are more uncertain, some measure of
easterly winds should take hold by late evening. There is even a
chance that storms in far SW AZ push a reinforcing SE outflow into
the metro well after midnight. It is also possible (20% chance) a
few elevated showers develop into the metro early Monday morning.
Otherwise, winds should switch to west by early Monday afternoon
with the potential for a SE outflow Monday evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
Under occasional passing mid/high clouds, southerly winds will be
favored at KBLH while E/SE directions at KIPL. Speeds will remain
fairly steady around 10kt with a few higher gusts. Some enhanced
winds due to long traveling outflows may be possible Monday morning
along with localized haze resulting from thick moisture increases.
NBM output shows 30% chance of morning showers at KBLH and 20% at
KIPL, but have not included any mention in this TAF package.
&&
.FIRE WEATHER...
Wednesday through Sunday:
Temperatures will generally be near to slightly below seasonal
averages through the period as monsoonal moisture remains in place
over the region. Storm activity is anticipated to spread as far west
as southeast California with most storms having good potential for
wetting rain (0.10" or more). Threats from storms will continue to
involve locally heavy rainfall and flash flooding along with strong
outflow winds and localized downbursts within storms. Significant
flooding may be experienced on previously burned areas of Gila
County, particularly during the second half of the week. Min RH
levels are expected to remain in the 20-30% range most areas (30-50%
higher terrain of south- central AZ). Max RH levels will be 35-60%
most places (60-90% higher terrain of south- central AZ). Apart from
thunderstorms, winds will favor familiar diurnal patterns.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...18
FIRE WEATHER...Sawtelle/Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
253 PM MDT Sun Jul 18 2021
.SHORT TERM...(This evening through Monday)
Issued at 249 PM MDT Sun Jul 18 2021
Area of strong to severe t-storms moving southward along the KS
border this afternoon, as MCV drops into central KS and associated
outflow boundary pushes southwestward into CO. CAPE values running
in the 2000-3000 j/kg range ahead of these storms, while 0-6km shear
has increased into the 30-35 kt range as low level winds turn more
sely under the wrn edge of the upper level jet streak over nwrn KS.
Expect severe storms to continue to move s-sw over
Kiowa/Baca/Prowers counties through 00z given amount of instability
and developing gust front, with most CAMs, especially the HRRR and
RAP, not helping the forecast much, as they have poorly modeled both
the instability and extent/strength of convection so far today.
Farther west, weak subsidence has limited convection to mostly
weak/isolated activity over the mountains, and as a result, cut back
pops to mainly isolated into the evening hrs given rather un-
impressive satellite/radar trends so far. Expect eastern plains
storms to slide south and east of the area by late evening, leaving
much of the region free of convection by midnight.
On Monday, drying mid-levels and continued subsidence suggest very
sparse afternoon convection over the mountains and valleys once
again, while n-ne steering currents should keep any activity away
from the I-25 corridor. Plains slightly more questionable, as
plentiful surface instability lingers near the KS border, with
potential for left-over outflows to force some very isolated
activity late in the day. Not enough confidence in this scenario to
include any pops yet, but mesoscale details need to be monitored
overnight and Mon morning for potential changes. Little change
expected in high temps, as typical mid-July heat continues.
.LONG TERM...(Monday night through Sunday)
Issued at 249 PM MDT Sun Jul 18 2021
...Forecast Key Points...
- Pattern shift shunts moisture westward.
- Warming trend east of Continental Divide.
- Recycling the moisture under the heat dome.
Well well well, how the turntables have turned. Going from a non-
soon the past couple of summers to a monsoon out west is fantastic
and the upcoming week, or next two, prove this the case. Areas east
of the Continental Divide will see fewer chances for showers and
storms, though not an entirely dry forecast.
Tuesday...A few isolated to scattered showers and storms around,
mostly the higher terrain, east of the Divide. West of the Divide, a
good dousing of moisture expected for sure.
Wednesday...Probably the most widespread active day in this period.
Remember the game `ring around the rosey`? This is like `ring around
the ridge-y` where in this case the rain comes falling down and
likely heavy at times, especially from I-25 westward. Upper level
flow will be more north to south so expect slow moving storms to pop
and then drift southward during the afternoon and evening hours as
we get a brief boost in monsoonal moisture from the west.
Temperatures look to top out a few degrees above mid-July averages
as well.
Thursday - Saturday...General trend is more active west and less
active east, with building heat. It really is hard to discern a
totally dry day across the region, except for maybe the far eastern
plains the later half of the work week. Moisture is around, though
not a lot east of the Divide (again), and the expanding ridge back
to the west would keep a lot of us on the drier side, and yet we`re
still carrying what would equate to a coin-flip for storm chances.
Confidence is just not there in this pattern to say yay or nay for
storms, or not. Temperatures again a few degrees above averages.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 249 PM MDT Sun Jul 18 2021
VFR conditions at all taf sites the next 24 hrs. Low risk of a
vcsh or vcts at KALS until 02z, while activity will likely stay
over the higher terrain west of KPUB and KCOS. Main impact from
any storms will be brief rainfall and gusty outflow winds. On
Monday, thunderstorm chances will continue to trend downward, with
only isolated convection over the mountains.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...HEAVENER
AVIATION...PETERSEN