Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/01/21
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
852 PM CDT Mon May 31 2021
.UPDATE...
Issued at 843 PM CDT Mon May 31 2021
Been watching an area of showers and thunderstorms developing the
past couple hours across southwest ND into extreme northwest SD
as shortwave energy moves into the Dakotas. A fair amount of
coverage noted across southwest ND and will monitor progress into
the nighttime hours. There is a weak low-level jet that develops
into north central SD later tonight, which could help maintain
some of this activity even after sunset. The latest run of the
HRRR does show a bit more areal coverage in the next 4 to 6 hours
across north central SD compared to previous runs. May have to
increase POPs a bit over this area if activity maintains itself.
Instability is weak over the region, so looking at general shower
and storm activity. Will watch trends after sunset and make
changes as needed. Currently have slight chances in the forecast
already.
As for overnight lows, temps look good for the time being. Pretty
low dewpoints across the eastern CWA could lead to coolish temps
tonight, potentially dropping a few degrees below forecast. Will
leave things alone for now though as mid and high clouds with the
approaching shortwave may squash that idea.
UPDATE Issued at 641 PM CDT Mon May 31 2021
Aviation discussion updated below for the 00Z TAFs.
&&
.DISCUSSION...
Issued at 242 PM CDT Mon May 31 2021
Presently, high pressure sits over the region leading to calm winds
and sunny skies. While light winds and a lack of mixing have made
it difficult for diurnal cu to form in the forecast area overall,
some has begun to develop in central South Dakota and should
continue to gradually expand this afternoon. Shortwave energy
supported by a 90 kt jet streak will gradually work its way through
the region Tuesday. Though there isn`t a ton of moisture available,
this will lead to the potential for isolated to scattered showers
through the day Tuesday and into Tuesday night. In addition,
though limited, enough instability looks to exist to where a few
thunderstorms during the afternoon and early evening hours are
possible.
A gradual warming trend takes place through the period as a west
CONUS ridge, along with southerly flow in the lower levels,
gradually works its way eastward through the week. The gradual
warming in temperatures will reach its crescendo Saturday when most
of the region will be in the mid to upper 90s. The one good thing
is that dewpoints have trended down a bit since yesterday and are
now progged to remain mostly in the 50s. If this remains the case,
while it will still be quite warm, apparent Ts won`t be quite as
stifling as they otherwise would have been.
Finally, models have backed off a bit on precipitation for the
upcoming weekend as model consensus tends to keep the ridge in
place longer than prior runs. Not to mention that 700 mb
temperatures of 12 to 15 degrees will likely prevent most
convection from initiating through Saturday night. NBM throws in
PoPs for Sunday night and Monday, however, as would be expected
for days 6 and 7, models diverge quite a bit at that point. The EC
never removes the ridge while the GFS and canadian bring a cold
frontal boundary through.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 641 PM CDT Mon May 31 2021
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are forecast to prevail during the TAF forecast
period. There may be a couple showers floating around KMBG around
sunrise, then near KABR and KPIR by late afternoon Tues. Coverage
is expected to remain isolated at best, so will just do a VCSH
mention at this time.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TMT
DISCUSSION...Telken
AVIATION...TMT
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1044 PM CDT Mon May 31 2021
.DISCUSSION...The 02Z HRRR run takes the conv complex up in the
Big Bend area south and southeast towards Deep South TX around the
early morning hours crossing mainly the central and western
portions of the area. This model appears to be initializing on the
ongoing conv pretty well and has shown pretty good run to run
consistency in moving it into Deep South TX/RGV. So have updated
the forecast wording to account for a little more potential conv
coverage over the central and western Counties.
&&
.PREV DISCUSSION... /issued 640 PM CDT Mon May 31 2021/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...The afternoon convection has remain confined to the
west of the RGV over the higher terrain of NE Mex. So far this
conv appears pretty stationary and does not pose an immediate
threat to the area airports. The HRRR and NAM12 guidance keep the
RGV free of conv overnight as the latest LAPS data shows
relatively more stable conditions over the eastern half of the
region with the highest CAPE values located over the far western
counties. Around or just after sunrise Tues, the HRRR/NAM12 then
want to pull some conv in over the region from the north. But
there remains big diffences in timing of the potential conv
initiation. For now will hold off on including any conv chcs for
the HRL and BRO airports throughout the upcoming 24 hours, but
will maintain some PROB30 groups for the MFE airport due to MFE
being a little bit close to the better conv chcs in the short
term. For aviation conditions will go with a blend of VFR/MVFR
conditions for all three RGV airports.
PREV DISCUSSION... /issued 253 PM CDT Mon May 31 2021/
SHORT TERM (Now through Tuesday Night): The short-term forecast
is a very complicated and challenging one to say the least. The
main focus in this forecast package has been the chances of
precipitation/thunderstorm development through the period.
As 500mb ridging continues to sit over central/northern Mexico
today, a longwave trough will dig southward out of the
Rockies/Plains and over Texas by this evening. An extension of the
trough will break away from the main mid/upper-level flow,
creating a cutoff Baja low by late tonight. As the trough
continues to dig into northern & central Texas this evening, the
ridging overhead will weaken/flatten out and help generate a
series of shortwave troughs upstream from Deep South Texas in the
process. The most difficult part of the forecast has been
analyzing how all of these interactions will evolve over the next
24 to 36 hours, which will play a key role in determining
precipitation chances. Seems like each deterministic & hi-res
model, although having a similar synoptic setup, has subtle
differences that in turn, have very different solutions.
Latest and current thinking is the rest of the afternoon and
evening will be dry under partly to mostly cloudy skies. A
Mesoscale Convective System (MCS) is expected to develop in
Coahuila, MX/Western Texas this evening as a result of a mid-level
shortwave trough. Hard to determine the exact path this MCS will
take, but the southern extent of it may sideswipe or clip portions
of the western CWFA overnight tonight or early-mid Tuesday
morning. The Storm Prediction Center has a Marginal Risk of severe
thunderstorms for Zapata and portions of western Starr Counties
in their D2 outlook to account for this scenario. The primary
threat with these storms that go severe will be gusty/damaging
wind gusts. The storms may spread into the middle part of the CWA
by mid-late morning, but less likely to be severe by that time. A
moist and unstable atmosphere will keep the threat of isolated to
scattered showers and thunderstorms possible through the day on
Tuesday across the region, though storm development will be very
conditional and highly dependent on what happens earlier in the
morning tomorrow. By Tuesday evening/night, another shortwave
trough is expected to develop over Mexico and push over Southern
Texas, likely developing another storm complex across northern
Mexico and/or southwest Texas that will move southeastward,
possibly impacting Deep South Texas. Even less is known about this
system, but most forecast models are at least acknowledging it at
this time. Will continue to monitor and update the forecast as
necessary.
LONG TERM (Wednesday through Monday): Unsettled (wetter) weather
will be the rule for much of the long term, especially up front
and into the early part of the weekend. Isolated stronger activity
on Tuesday night will wind down by the beginning of the long
term, i.e. Wednesday. The lower RGV initially will still be
looking at a mid level cut off low over Baja California extending
southwest from a larger scale trough over the Plains, with broad
surface high pressure over the Northwest Gulf. The influx of low
level Gulf moisture on southeast winds, coupled with instability
over the Sierra Madre Oriental Range to the west, will support
scattered shower and general thunderstorm activity Wednesday
night. As always, attention to eastward propagating cells will be
required.
The Plains trough will start to edge eastward into the Midwest on
Thursday, while the Baja low will also shift east into a slightly
more compact area over West Texas. Another round of Sierra Madre
convection will be possible Thursday night as energy aloft moves
over the mountains. The long range models are broadbrushing the
CWA with precip on Wednesday, Thursday, and Friday, with WPC
forecasting modest amounts below an inch each of those days. It
will be difficult to pinpoint which areas will see the best rain
chances and the most rain. However, it is June and pockets of
locally heavy rain will be possible. Saturday may be the best day
for rain as the remnant Baja low, still well defined aloft, will
move east across Central Texas. An inch or two of rain may fall on
Saturday with the low in close proximity. Though H5 solutions are
similar, the ECMWF appears to be a bit more aggressive than the
GFS with QPF on Saturday.
Consensus temperatures for the period are near normal; 70s for
overnight lows and 90s for daytime highs with some lower bias due to
higher rain chances.
Upstream ridging will edge closer on Sunday and Monday, with rain
chances trending lower as a result. Slightly drier air will work
into the area from the west on Monday and Tuesday, but this will not
last long before upper ridging shifts northeast and Gulf moisture
regains the upper hand.
MARINE:
Now through Tuesday Night...Mostly favorable and tranquil marine
conditions will prevail on the Laguna Madre and Gulf waters
through Tuesday night as broad high pressure sits over the
northern Gulf of Mexico. Light to moderate southeast winds and low
to moderate seas will prevail through the period. Isolated to
scattered showers and thunderstorms will be possible from time to
time.
Wednesday through Saturday Night: Light to moderate southeast
winds and low to moderate seas will prevail through the period.
Isolated to scattered showers and thunderstorms will be possible
from time to time.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 77 89 76 86 / 10 30 20 30
BROWNSVILLE 77 90 77 89 / 10 30 20 30
HARLINGEN 75 91 74 88 / 10 30 20 30
MCALLEN 77 92 75 91 / 10 40 40 40
RIO GRANDE CITY 76 94 73 92 / 30 40 60 50
SOUTH PADRE ISLAND 79 82 78 82 / 10 20 20 30
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
Short Term/Aviation...60-Speece
Long Term/Upper Air...55-Adams
Area Forecast Discussion
National Weather Service Dodge City KS
1035 PM CDT Mon May 31 2021
...Updated Aviation...
.SHORT TERM...(This evening through Tuesday)
Issued at 1232 PM CDT Mon May 31 2021
Early afternoon radar observations show light rain is exiting our
eastern zones, marking the end of the measurable precipitation in
our area for the day. In the wake of the overnight rain,
widespread thick stratus is in place over southwest KS with spotty
drizzle. Guidance agrees this cloud cover and drizzle are not
going anywhere anytime soon, leaving the entirety of southwest KS
with a cold, gloomy Memorial Day. Light north to northeast winds
will do nothing to help the cause, and afternoon high temperatures
will struggle to breach 60. Later tonight, guidance and various
CAMs suggest drizzle will become more widespread, and with
continued overcast skies, overnight lows will drop only slightly
into the low 50s.
An upper level shortwave trough over the northern plains Tuesday
morning will dig southeast during the day, likely maintaining the
overcast skies/drizzle over southwest KS and continued below
average temperatures. Despite these factors, NAM/GFS/ECMWF all
agree that a few degrees of warming at 850-mb will translate to
afternoon highs in the upper 60s across southwest KS. However,
given the amount of recent precipitation, overcast skies, and
north/northeast winds, this may be overdone.
.LONG TERM...(Tuesday night through Monday)
Issued at 243 PM CDT Mon May 31 2021
The much advertised Rex Block upper level pattern will be emerging
at the beginning of the long term period as a ridge builds over
the Pacific Northwest/Great Basin and a weak cut-off low sits over
far northwest Mexico. The amplifying upper trough over the High
Plains/Midwest will shift east, and weather conditions over
southwest KS will begin to improve. Skies will still be mostly
cloudy Wednesday morning, but should clear out by afternoon, and
highs will warm into the mid to upper 70s. The upper level pattern
will slide eastward on Thursday/Friday, but only slightly, leading
to very similar weather conditions in our area both days. Expect
partly cloudy skies, light southwest to southeast winds, and
afternoon highs increasing from the low 80s Thursday to the
mid/upper 80s Friday.
By this weekend, the upper level pattern will be dominated by a
longwave ridge over essentially the entire CONUS, with the
aforementioned weak cut-off low drifting northeast into the
southern plains, and the strongest mid/upper level flow confined
to near the US/Canada border. This kind of pattern is consistent
with continued quiet, warm weather, and afternoon highs
Saturday/Sunday will be in the mid to upper 80s under partly
cloudy skies.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1035 PM CDT Mon May 31 2021
Stratus is expected to reestablish across SW KS over the next few
hours, with IFR/LIFR ceilings expected at all airports through 12z
Tue. Areas of drizzle/mist/BR are expected during this time as
well, limiting visibility. Consensus of short term models shows
stratus ceilings gradually lifting to a VFR broken stratocumulus
deck during the daylight hours Tuesday. HRRR suggests isolated
rain showers near DDC/HYS by 22z Tue, with some modest
instability. With coverage limited, kept mention out of the TAFs
for now. Winds will be very light, and at times variable in
direction, during this TAF cycle.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 67 51 75 / 10 20 10 20
GCK 50 68 49 75 / 10 20 10 10
EHA 50 70 50 78 / 10 20 20 10
LBL 53 69 49 77 / 10 20 10 20
HYS 53 67 50 75 / 10 20 10 20
P28 55 69 53 75 / 10 20 10 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Turner
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
640 PM CDT Mon May 31 2021
.AVIATION...
Scattered showers are popping up near the I35 sites with stronger
activity west of DRT. This activity is expected to grow in areal
coverage as it moves southeast overnight. Have timed the TAFs with
tempo groups for the most likely period of thunderstorms for each
terminal. In addition to the rain chances, another period of MVFR/IFR
conditions are expected overnight as ceilings lower once again. The
threat for additional storms tomorrow depends on how the overnight
period evolves. Have left the forecast for tomorrow dry for now in
the TAFs, but will reassess once tonight`s evolution becomes more
apparent.
&&
.PREV DISCUSSION... /ISSUED 600 PM CDT Mon May 31 2021/
UPDATE...
A boundary can be seen on area radars moving near the northern border
of the CWA in the Hill Country and Edwards Plateau. Shower and storm
activity is on the increase along and north of the boundary. To the
west, severe storms remain west of Val Verde County and are slowly
moving east. To our north, a complex of strong to severe storms are
remaining north of the Waco area. Think the biggest threat in the
near-term for severe weather chances will be out in Val Verde County.
The latest meso-analysis shows a CAPE axis along the Rio Grande
where these storms should move along. If they do maintain their
intensity think they will move into western Val Verde County around
00z.
Depending on how the boundary in the Hill Country evolves, this
complex could grow upscale into a cluster that moves through much of
the CWA like the past several runs of the HRRR has shown. Have
increased PoPs substantially for the tonight period to account for
increasing trends on radar and in the latest hi-res model guidance.
PREV DISCUSSION... /ISSUED 248 PM CDT Mon May 31 2021/
SHORT TERM (Today through Tuesday)...
Latest radar imagery depicts isolated showers and thunderstorms over
our eastern row of counties this afternoon. Meanwhile, aloft and to
the west, an H5 trough will attempt to slide eastward before cutting
off an upper low over the northern Baja of California. This cutoff
low will be the main player in terms of our rain and storm chances
over the next 24-36 hours.
We should see partly to mostly cloudy skies through the afternoon
and early evening hours as we await our next round of thunderstorms.
SPC currently has areas along and west of a Rocksprings to Spofford
line within a Slight Risk (2/5) and areas generally along and west
of the I-35 corridor within a Marginal Risk (1/5) for severe storms
late this evening into early Tuesday morning. The latest SPC
Mesoanalysis shows some good instability already in place despite
residual cloud cover from earlier convection out west. With MLCAPE
forecast to be between 2000-3000 J/kg, 0-6km bulk shear of 40-50 kts
over Val Verde, Edwards, and Kinney Counties, and modest elevated
lapse rates of 7 to 7.5 C/km, expect the primary concern to be large
hail, along with some isolated damaging wind gusts. As storms grow
upscale into a complex or several different clusters, they will move
into the Hill Country and then the I-35 corridor before weakening by
early morning. Even with a weakening trend, the heavy rain/flooding
threat will once again rear its ugly head, with PWATs nearing 2" for
most early Tuesday morning, along with a very moist column on
forecast soundings, rainfall rates of 1-2" per hour are very much
within reach with any storms that move through the region. With
already saturated soils, in addition to swollen rivers and creeks,
it won`t take long to see the threat for localized flooding to
materialize.
Tuesday will present the greatest challenge in terms of timing and
coverage of storms. As of the latest run of CAMs, most indicate this
complex will move out by Tuesday morning, with the 12Z NAM the most
bullish, keeping storms around through at least 18Z then pushing
things out of the region by mid afternoon. If this scenario unfolds,
believe that the atmosphere will be mostly worked over and have
trouble destabilizing in time for afternoon convection to form out
west. However, if storms exit before midday, that should give the
atmosphere enough time to recharge the batteries and fire up storms
along the Rio Grande by mid to late afternoon. For the most part,
the shortwave responsible for storms earlier in the day will be too
far east for any sort of decent synoptic forcing for redevelopment.
At this time, will keep PoPs in play as mesoscale/storm interaction
is difficult to pin down at this distance. Ultimately, believe that
storms will probably develop along the dryline boundary out west and
move in by late Tuesday evening, with a few of them being on the
strong side.
LONG TERM (Tuesday Night through Sunday)...
Synoptically the trough across Arizona in the short term will deepen
and cut off by Tuesday night and Wednesday morning. The low will
spin over Baja California through Thursday then begin to move east
towards Texas. The GFS and ECMWF both bring the upper low directly
over our area by mid-day on Saturday before the models diverge for
Sunday and Monday. The trough gets drown into the broad southwest
flow aloft by Monday in the GFS, while the ECMWF has the system
lingering across north Texas. The Canadian differs completely with a
broad ridge developing across the West and the large trough cutting
off over the Mississippi Valley on Saturday. Within this broad
pattern shortwaves will continue to be ejected across Texas for
Wednesday and Thursday.
This overall pattern will continue to lead to a messy forecast. There
is general consensus in the rainy pattern lasting through at least
Saturday, but the details of timing and placement of storms remain
low confidence with isolated storms and MCS complexes being driven
by mesoscale features (like outflows and upstream convection) that
the synoptic models struggle to resolve at times.
What will follow is a general consensus of what the models stay for
each day. For Wednesday the 3 longer term models (GFS/ECMWF/Canadian)
have a stalled front through our area with possibly a decaying MCS
moving across our Edwards Plateau counties. The outlier for Wednesday
is the NAM which also shows the front, but keeps the area mostly dry
Wednesday (behind the large MCS on Tuesday) other than an isolated
storm or two across the Edwards Plateau by late in the day on
Wednesday. Thursday could see the next shortwave moving across South
Central Texas, with most models continuing to show QPF spread across
much of the area. By Friday the pesky (yup, I used that term the last
time we had this setup and here it is again!) upper low should
finally begin its eastward movement, being centered around the Texas
Big Bend by mid-day on Friday. Ahead of the upper low Precipitable
water values increase to 1.8 to over 2 inches east of the I-35
corridor. The GFS and ECMWF pick up on the moist environment and the
lift that upper low passing overhead will provide and peg Saturday
and Saturday night as very rainy across much of the area with locally
heavy rainfall likely.
Looking at the QPF values as a whole the quartet of models
(NAM/GFS/ECMWF/Canadian) all have widespread 1-3 inch totals
(including rains from the short term) with a few bullseye of higher
4-5 inch totals. Adding in the weekend those totals balloon up to 3
to 6 inches from the GFS and ECMWF signifying the heavier rain event
on Saturday may be our main show through the long term. The Canadian
is the outlier in the long term as it weakens our upper low to the
west leading to lower rainfall totals overall.
With the ongoing clouds and rainfall high temperatures each afternoon
will be warm (in the low 80s to low 90s), but will run below
climatological normals for the beginning of June.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 69 85 69 82 66 / 70 50 60 70 40
Austin Bergstrom Intl Airport 70 85 69 83 65 / 70 50 60 70 40
New Braunfels Muni Airport 70 87 70 85 67 / 60 40 60 70 30
Burnet Muni Airport 67 81 66 81 64 / 80 50 60 70 40
Del Rio Intl Airport 69 85 70 86 69 / 80 50 70 60 40
Georgetown Muni Airport 69 84 67 81 64 / 80 50 60 70 40
Hondo Muni Airport 69 85 68 85 67 / 50 50 70 70 40
San Marcos Muni Airport 70 86 70 83 65 / 70 40 60 70 30
La Grange - Fayette Regional 72 87 72 85 69 / 50 40 50 70 30
San Antonio Intl Airport 70 86 70 83 69 / 60 40 60 80 30
Stinson Muni Airport 71 88 71 86 69 / 50 40 60 70 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Hampshire
Long-Term...Brady
Decision Support...Oaks
Area Forecast Discussion
National Weather Service Fort Worth TX
831 PM CDT Mon May 31 2021
...New Short Term, Aviation...
.SHORT TERM... /NEW/
/Now through Tuesday/
A complex of showers and thunderstorms continues to move through
North and Central Texas at this hour. Latest RAP objective
analysis indicates around 1500 J/kg of MLCAPE across our far
southeast counties, so a strong wind gust still can`t be ruled out
with the strongest storms in that area. Elsewhere, a very moist
airmass remains in place and efficient rainfall production has
led to heavy rainfall and flash flooding across the region. As the
main shortwave responsible for this activity continues to move
east, most of the showers and thunderstorms should push out of our
area later tonight. At the surface, a weak area of low pressure is
centered just north of Wichita Falls with a cold front draped
across central Oklahoma into West Texas. This front will slide
southward overnight and could be a source for additional
convective development, however, instability is waning in the wake
of this afternoon`s complex and chances appear to be diminishing.
We`ve lowered PoPs overnight across the region, although we`ll
keep some 30-40% PoPs along the front through the overnight hours.
Any additional rainfall will result in continued flooding issues.
Latest guidance continues to suggest that the front will push
through our area early tomorrow and despite weak large scale
ascent, we`ll remain generally precipitation free. While it should
be noticeably less active, we`ll keep some low rain/storm chances
along the front across our southern counties. Rain chances should
increase again late tomorrow night as another surge of moisture
spreads northward.
Dunn
&&
.LONG TERM... /Issued 303 PM CDT Mon May 31 2021/
/Tuesday night through next Monday/
The main story of the extended portion of the forecast continues to
be the daily precipitation chances across North and Central TX
through the next weekend. The combination of the rain and clouds
will keep the temperatures below average with highs in the upper 70s
to mid 80s and lows generally in the mid/upper 60s to near 70
degrees.
The highest precipitation chances will slowly shift to East and
Central TX Tuesday night into Wednesday as the weak cold front
settle over this area. For the rest of us, expect spotty showers and
storms with a coverage between 20-30% throughout the day on
Wednesday. There`s a chance that our region remains precipitation-
free during the day due to some subsidence in the wake of the front.
A couple of disturbances will travel across our region late week and
into the weekend, as the upper level trough continues its way to
the east and another mid-level low pressure settle over the
southwest CONUS and northern Mexico. This will keep PoPs in the
forecast through his weekend, with best chances across Central TX.
At this time, flooding rainfall will be the main concerns throughout
the week with heavy rain possible each day. However, we can`t
rule out some brief gusty winds with some of the stronger storms.
Flash flooding issues will likely increase each across those
locations that see multiple rounds of heavy rain throughout the
next several days.
Sanchez
&&
.AVIATION... /NEW/
/00Z TAFs/
VFR prevails across the Metroplex at this hour in the wake of
heavier rainfall, and the 00Z Fort Worth sounding shows quite a
bit of dry air below 10,000 ft. Given all of the rainfall and
diminishing winds, we should see reductions in cig/vis during the
overnight hours. We`ll continue with IFR cigs after midnight and
assess this through the late evening as vis restrictions may be
the bigger issue toward morning. Wind fields were northerly
earlier but have recovered in the wake of convection and are
primarily easterly now. We should see a gradual shift to northerly
winds as the front moves through late tonight.
Cigs/vis will improve during the day Tuesday with VFR prevailing
by afternoon.
Dunn
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 68 80 65 83 66 / 100 20 30 30 20
Waco 68 80 66 80 65 / 100 30 50 60 30
Paris 66 78 63 79 62 / 100 30 20 30 20
Denton 64 76 60 81 62 / 90 20 20 30 20
McKinney 66 78 62 81 63 / 100 30 20 30 20
Dallas 68 81 67 83 67 / 100 30 30 40 20
Terrell 66 79 64 81 64 / 100 30 30 40 30
Corsicana 69 81 66 81 66 / 100 30 50 50 30
Temple 67 80 65 80 65 / 100 20 50 60 30
Mineral Wells 64 76 60 81 63 / 80 10 30 40 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT Tuesday for TXZ091>094-100>104-
115>120-129>134-141.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
620 PM CDT Mon May 31 2021
.DISCUSSION...(This evening through Monday)
Issued at 438 PM CDT Mon May 31 2021
General overview of the entire 7-day forecast:
Very basically, this next week as a whole will be decidedly-drier
and noticeably warmer than the past several days have been. In
fact, Thursday should kick off a multiple-day stretch of
prevailing ABOVE normal high temps in the 80s, making for solidly
more "summery" feel out there. In the very short term (next 12-18
hours) our main hazardous weather focus is on the potential for
perhaps fairly widespread fog late tonight into Tues AM (although
the likelihood/coverage of truly dense fog is still a bit in
question).
Precipitation/thunderstorm overview:
After having several rounds of at least light measurable rain over
the past week, confidence is high that these next 7 days as a
whole will allow most places to dry out sufficiently to make
outdoor and field work a more promising bet. That being said, the
forecast is not 100 percent/guaranteed dry all areas either. Right
off the bat tonight into tomorrow, mainly parts of our KS zones
remain prone to some pesky, fairly hit-and-miss shower activity.
Then Wednesday brings a slight chance of showers/a few non-severe
storms to mainly western zones. Beyond that though, our official
forecast goes completely dry across our entire coverage area (CWA)
for several days (been a while since we`ve seen that!) as
predominant upper level ridging/lack of forcing takes over.
Finally, at the very end of the forecast period, some highly
uncertain (and thus smallish) rain/thunderstorm chances (PoPs)
make a return for Sunday night-Monday. Even if these chances do
come to fruition late this weekend into Monday, early indications
suggest that seasonably-weak wind shear should keep an organized
severe storm threat at bay. However, and although FAR from a sure
thing, peeking just beyond the current forecast perhaps our next
low-confidence prospects for severe storms in or at least near our
CWA perhaps arriving around Tuesday the 8th as both the ECMWF/GFS
hint at a disturbance brushing the region downstream from a large
scale western CONUS trough. Again, this is over a week out, so far
too soon to put much stock it. And in the meantime, the bottom
line is that at least the first full week of June will surely be
unusually quiet in the severe storm department.
Temperature overview:
As mentioned, those lovers of more summer-like temperatures are
really going to enjoy Thursday and beyond, as we look to enter a
consistently warmer (some would say hotter) weather pattern, as we
look to really kick our recent/still-ongoing cooler stretch into
the rearview mirror. See below for more details specifically for
Tues-Wed, but these are clearly the two coolest of the next 7 days
with highs in the 70s (and lows the next 2 nights a few degrees
either side of 50). Then starting Thursday, at least low 80s look
like a good bet all areas, with better potential for mid-upper 80s
arriving for Friday and into this weekend, although this warming
will also be accompanied by a return to breezy southerly winds.
With the big-picture stuff covered above, will transition to a
closer look at current/very recent weather and more detailed
breakdown solely of the next 48 hours/4 forecast periods:
Current/recent weather scene as of 330 PM:
As expected for a few days now, today has truly been the "pick"
weather of the 3-day holiday weekend, and if anything it has
probably been a bit warmer/less rainy/more pleasant than expected
(especially versus expectations of a few days ago). That being
said, conditions do vary somewhat across our CWA. Most notably,
while the vast majority of our Neb zones are enjoying no worse
than partly cloudy skies (under varying degrees of shallow/fair
weather stratocumulus), most of our KS zones have endured a
considerably-cloudier day, although most spotty rain showers from
earlier in the day have long since faded/moved out. As a result of
the varying sky cover, high temps are on track to top out 70-73 in
most of our Neb zones, but with most of our KS zones only reaching
low-mid 60s (perhaps some upper 60s near the state line). In the
mid-upper levels, water vapor satellite and short term model data
reveals that our region resides within a broad, positively-tilted
trough axis bisecting the CONUS from northeast-southwest, but
with a lack of meaningful forcing/instability keeping us dry at
this time in the wake of last night`s/this morning`s latest round
of rain that mainly affected our southern zones. At the surface, a
weak pressure gradient is in place locally, but enough between
weak high pressure east and lower pressure west to promote
generally easterly breezes sustained 5-10 MPH (with only
occasional higher gusts to around 15 MPH).
This evening-tonight:
Potential fog issues are the main thing. The vast majority of the
CWA should see a dry /precip- free night. Have continued to trend
down/remove PoPs versus previous forecasts, with have lingered
some very small chances for spotty showers/sprinkles within our KS
zones within a zone of mid level saturation/weak forcing (although
latest models suggest the bulk of any such activity should remain
just south of our domain). At the surface tonight, light wind
speeds mainly around 5 MPH or less will prevail, with direction
gradually shifting from more easterly to more westerly with time.
Am starting to think that going forecast probably has a bit too
much sky cover (especially north of the state line) with mainly
clear skies probably prevailing over most Neb zones especially if
transient high cirrus does not drift overhead as suggested by some
12Z models. Obviously the light winds and mainly no worse than
partly cloudy skies should be a decent cooling setup, and kept
lows similar to previous forecast mainly in the 47-51 range. Given
a lingering, fairly moist boundary layer (especially south of I-80
down into KS), at least widespread light-moderate fog is looking
like a decent bet post-midnight, and there remain concerns (as
relayed by previous shift) that we could be looking at a several-
county area of moderate-to-dense fog, probably focused 40 miles
either side of the state line per latest HRRR visibility progs.
That being said, confidence is only medium at this time regarding
whether dense fog will end up widespread enough to warrant a
formal Advisory, as any passing high level clouds could
delay/disrupt its development...not to mention that SREF
percentages for visibility under 3 miles is unusually low at this
time. In the end, have continued to hit "areas/widespread fog" in
the forecast itself mainly in the southern half of the CWA and
have continue to highlight potentially-dense fog potential in our
HWO, but confidence just not there at this 9-12+ hour range to
hoist a formal Advisory.
Tuesday daytime:
See above for any early morning fog/dense fog potential, but any
fog that does materialize should largely improve/dissipate by 9-10
AM (typical of late spring/early summer fog situations). In other
departments, it`s looking like a warmer and somewhere between
mostly sunny and partly cloudy day for the vast majority of the
CWA. The latest RAP hints that KS zones could be most subject to
more widespread/stubborn lower clouds, while most Neb zones should
see only limited/passing mid-high clouds. Precip-wise, have
lowered but still maintained some slight Pops/sprinkle potential
mainly in our KS zones and far southeast Neb zones, but latest
HRRR and especially NAMNest really don`t show this amounting to
much. Our string of fairly light wind days will continue, with
very light morning speeds giving way to only sustained 10
MPH/gusts around 15 MPH) out of the southeast in the afternoon.
Assuming that sky cover is not greater than expected, high temps
should have little problem reaching the low-mid 70s (overall-
warmest northeast half).
Tuesday evening/night:
Extended-hour high-res solutions from HRRR/RAP suggest we may have
another "fog problem" on our hands, but with plenty of uncertainty
in the shorter-term fog situation and with SREF low-visibility
percentages remaining almost surprisingly-low, have opted against
a formal 3rd-period fog introduction at this time. Otherwise,
other than lingering a slight chance of spotty showers/sprinkles
in south-southeast zones right away in the evening, confidence is
fairly high in a dry night. In the presence of light southerly
breezes, low temps are aimed similar to tonight...within a few
degrees either side of 50.
Wednesday daytime:
Despite the official forecast maintaining a formal slight chance
(20 percent) of showers and/or thunderstorms for all areas in the
afternoon, raw model data (particularly form the 18Z NAM/NAMnest)
strongly suggest that the majority of the CWA will likely remain
dry, with any mid-late afternoon showers/storms most favored
within/near our far west-central/northwestern Neb zones (Ord-
Lexington area), where a broken line of fairly weak convection
could develop along a subtle surface trough axis, and under a low
amplitude disturbance passing overhead in north-northwest flow
aloft. Latest NAM suggests perhaps as much as 500-800 J/kg mixed
layer CAPE in our western zones, so although severe storms appear
fairly unlikely, probably cannot rule out some gusty winds/small
hail should storms materialize. Obviously some uncertainty given
this is 48 hours out (not to mention that SPC doesn`t even
officially have "general thunder" in our west on the current Day 3
outlook), but at least for now felt it was worth introducing a
slight chance of thunderstorms west (as opposed to just showers).
In other departments, temps should continue a slow climb, with
highs aimed into the mid-upper 70s, in the presence of fairly
light southerly breezes.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 611 PM CDT Mon May 31 2021
Overall...quiet conditions are expected at the terminal sites for
this TAF period, with the main concern being with the potential
for fog. A weaker sfc pattern in place is expected to keep winds
light and at time variable this evening through the
overnight/early Tues AM hours, turning more SSErly for the mid-
morning/aftn hours Tues. Not a whole lot of cloud cover is
expected overnight, and with the light winds, models continue to
show the potential for fog, with some differences with just how
widespread it is. Some focus the worst conditions near the state
line, others saying it perhaps could creep further north closer to
HWY 6/I80. At this point kept things bottomed out in the MVFR
category, but worse conditions are not out of the question, just
not confident enough at this point to have it in the TAF.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...ADP
Area Forecast Discussion
National Weather Service Marquette MI
649 PM EDT Mon May 31 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 649 PM EDT MON MAY 31 2021
WV imagery and RAP analysis indicated a mid/upper level trough from
Hudson Bay to the Upper Mississippi Valley. A compact shortwave/vort
moving through western Upper Michigan along with MLCAPE into the 500-
1000 J/Kg range supported sct/nmrs shra/tsra from central Upper
Michigan into northern Wisconsin. Mainly pea-sized hail was reported
and gusty winds were reported with the stronger storms.
Rest of today and Tonight, the remaining convection should diminish
and end this evening with the loss of daytime heating and as the
shrtwv moves off to the east. Any stronger storms will be mainly
over the southeast half of Upper Michigan. Lingering low level
moisture after the rainfall followed by clearing skies and favorable
radiaional cooling conditions will result in some patchy fog
development.
Tuesday, mid level and surface ridging will bring mostly sunny skies
which will push temps into the mid 70s inland. Even with dewpoints
into the lower 40s over the west half and RH values from 25-30 pct,
the recent rainfall, light winds will limit fire weather concerns. A
few CAMs still suggest some -shra may develop, but model trends
along with with the expected low level mixing and drying, continued
to leave out mention in the forecast.
.LONG TERM...(Tuesday night through Monday)
Issued at 434 PM EDT MON MAY 31 2021
Broad troughing will be in place across the Great Lakes region to
start the extended period with building ridging across the Pacific
NW. A series of low ampltiude shortwave troughs move through
Wednesday morning through Thursday night. Boundary layer moisture
appears limited, but a few lake breeze showers and thunderstorms
should be expected on Thursday. The Pacific NW riding shifts east
late this week bringing much warmer temperatures and muggy
conditions back into Upper Michigan through the end of the extended
period.
Warm and dry is the primary weather pattern, but some lake breeze
thunderstorms can`t be ruled out as moisture increases late this
week. If precipitation occurs then the greatest probability will be
during the afternoons/evenings along any lake breeze boundary that
manages to push inland. It`s difficult to determine where lake
breeze boundaries will set up, but light southerly winds suggests
the Lake Michigan boundary will be dominant on Wednesday and
Thursday. More importantly, moisture increases each day with model
soundings indicating near zero CAPE on Wednesday, up to 1000 J/kg on
Thursday, and up to 2000 J/kg on Friday.
Active weather limited the amount of time I had to dig into the
particulars of the long-range forecast. However, NAEFS guidance
indicates 850 mb temperatures warming above the 90th percentile on
Friday and lingering there through the end of the extended period.
Additionally, precipitable water values increase above average on
Thursday and perhaps above the 90th percentile by Monday or Tuesday
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 649 PM EDT MON MAY 31 2021
VFR conditions are expected through the forecast period. Some fog
may also be possible late tonight into Tue morning at KSAW as low
level moisture lingers and skies clear.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 649 PM EDT MON MAY 31 2021
No real marine concerns as weak pressure gradients will lead to
winds of 20 knots or less through the period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...EK
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Phoenix AZ
513 PM MST Mon May 31 2021
.UPDATE...
Updated Aviation discussion.
&&
.SYNOPSIS...
Seasonably dry and warm conditions will persist under mostly clear
skies through tomorrow. High temperatures will warm slightly by the
middle of the week but a persistent weak upper level low and a
slight uptick in cloud cover and moisture may be enough for isolated
showers and thunderstorms in Arizona most afternoons. Showers and
storms are most favored over the higher terrain north and east of
Phoenix but an isolated shower or thunderstorm can not be entirely
ruled out for the Phoenix area the second half of the week.
&&
.DISCUSSION...
Today`s upper level analysis shows a high-amplitude wave pattern
with a strong high pressure ridge axis over the PAC NW into W Canada
and a large, weak longwave trough from offshore Baja to the 4-
Corners and S/central Rockies. UL RAP analysis also shows an H5 low
pressure circulation beginning to develop into a cut-off low near-S
of Phoenix with upstream N flow across the Intermountain W on the
E flank of the ridge.
METSAT showed clear skies across the region with convective CU and
isolated mostly light showers/sprinkles radar returns forming across
N and E AZ. Mid level WV imagery showing slightly elevated moisture
in those same areas. Various UL vort max anomalies were also noted N
and S of the area. Local ACARs soundings evolution showed several
degrees of cooling aloft from 650 mb and upwards, with midday PW
increased from ~0.35" yesterday to almost 0.70" today.
On this sunny Memorial day expect yesterday`s near normal trend to
continue today with highs topping out in Phoenix and the lower
deserts at 99-101 degrees, and a couple of degrees warmer out west.
Models now agree on the upper low cutting off and retrograding
towards the SW over Central Baja by tomorrow as the strong high
pressure ridge shifts east and builds over the W US States to create
somewhat of a rex block pattern. The cut-off low is expected to
remain mostly stationary through Thu as the ridge maintains strength
over the West US while only shifting slightly east also through
Thu. As a result there is good confidence of a warming through Wed
with moderate heat risk and highs of 103-105 degrees in Phoenix
and the lower deserts, and 104-108 out west. Highs are then
expected stay close to this range through Sat.
The lingering low pressure system will also make for low-end
shower/storm chances each afternoon and evening for much of the
week. The HREF family and the NMM6Km are in good agreement on very
isolated, weak high-terrain/Mogollon Rim showers/storms today-
tomorrow, afternoon-evening. These would be high-based storms
with dry lightning and gusty outflow wind potential with little
to no rainfall. Although the low will be in position to rotate
small vort disturbances across the area for a few days, it is
still fairly weak and unable to attract more pronounced mid level
(and BL) moisture with the GEFs plume showing PW spiking near
0.85" late this week. In addition there are no IVT moisture plumes
currently depicted in ensembles with this system.
The Clusters analysis for Thu favor the stationary closed low over
Central Baja with the massive ridge still parked over the W US. For
Friday they favor a flattening ridge to the N and the ridge axis
shifting into the NE Plains with flattened lingering high pressure
and weak flow over the Desert SW. For QPF a minority of clusters
still favor very isolated showers/storms including the lower
deserts. This is where the NBM picks up on an uptick on POPs for
Thu evening and night from less than 10% to near 15% through very
early Fri morning.
However the much more likely and bullish solution favored by the
Clusters is dry conditions associated with the strong mid-late
week high pressure building and the maintenance to near 104
degree high temps through Saturday and a few degrees warmer out
west.
&&
.AVIATION...Updated at 0013Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
A weak upper trough over the Desert Southwest and far northwest
Mexico is aiding the development of isolated thunderstorms over
the higher terrain of Arizona. Storms currently over southeast
Yavapai and northwest Gila Counties are slowly drifting toward
metro Phoenix. However, they are expected to dissipate before
reaching the Valley floor. But, some modest outflow from those
storms may enter northern and eastern portions of the metro area.
For the TAF sites, KDVT would most likely be affected - if at all.
Otherwise, surface winds will follow familiar warm season diurnal
patterns with relatively long lived upvalley/westerly winds this
evening before trending to downvalley/easterly directions.
Anticipate redevelopment of upvalley/westerly flow by midday.
There will be isolated thunderstorms over the higher terrain
Tuesday afternoon. At this time, it is anticipated that there will
be more storm coverage over southern Gila County which could make
for a little better potential for outflow winds reaching the
Valley floor in the evening. Skies will be mostly clear except for
minor amounts of debris cloudiness this evening AOA FL120 followed
by distant storm development over the mountains Tuesday
afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
There is a weak upper trough over the Desert Southwest and far
northwest Mexico. But, skies will be clear except for minor
amounts of mid and high clouds. Surface winds will favor
southeasterly at KIPL through the day Tuesday with little to no
downvalley/westerly winds tonight. Southerly winds will be favored
at KBLH through Tuesday with afternoon and early evening gustiness
(20-25kts).
&&
.FIRE WEATHER...
Thursday through Monday:
Expect max temps to remain slightly above normal through Saturday.
A gradual increase in moisture is likely to bring some isolated
thunderstorms mainly over the AZ high terrain, with lower desert
storms not entirely out of the question, though much less likely.
However, wetting rains are not anticipated, so these isolated
storms may pose a dry lightning threat. Min RH values will remain
quite low, mostly staying between 7-12% each day. Daily max RHs
will mostly range from 20-30% with higher readings across the
western deserts. Winds will remain light to moderate through the
bulk of the period, but with typical afternoon breeziness most
days. Outflow winds, even from distant thunderstorms, cannot be
ruled out for any particular day either.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...Hodges/Benedict
FIRE WEATHER...Sawtelle/Hodges
Area Forecast Discussion
National Weather Service Pueblo CO
546 PM MDT Mon May 31 2021
.UPDATE...
Issued at 544 PM MDT Mon May 31 2021
Updated POPs to reflect more recent precip trends.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 323 PM MDT Mon May 31 2021
Main wave of showers, with some weak tsra embedded, was rolling
through the eastern mountains and into the I-25 corridor as of 21z,
while more isolated convection persisted farther west toward the
Continental Divide. Have seen some small hail and gusty winds with a
few of the stronger storms moving across the San Luis Valley, though
activity has remained mainly sub-severe as instability and shear are
fairly marginal given weakening wind field aloft under the upper
trough and rather extensive cloud cover limiting heating. While
threat of heavy/flooding rains on area burn scars seems to be
decreasing this afternoon, radar shows some stronger cells still
west of the Spring scar, while HRRR suggests a risk of a couple
stronger cells back toward Hayden Pass until 00z-01z, so will keep
the current flash flood watch in place. Showers and a brief rumble
of thunder will continue into the evening, as wave of enhanced
upward motion moves through, and nudged pops higher on the plains
east of I-25 to account for more aggressive HRRR dragging convection
eastward through 04z. Most activity then fades away by midnight,
with perhaps some lingering light rain near the NM border into Tue
morning. Snow level falls to around 10k feet this evening (currently
snowing near the summit of La Veta Pass), with some 1-3 inch
accumulations over the higher peaks of the Sangres/Pikes Peak this
evening.
On Tuesday, upper low shifts eastward, with flow aloft become n-nw
over Colorado. Some drying in the mid and lower levels should lead
to more sun and warmer temps at many locations, before secondary
wave and strengthening upper level jet drop into the state in the
afternoon. Should be enough forcing plus residual moisture to
generate scattered tsra over the mountains and interior valleys by
mid-afternoon, with activity slipping into the I-25 corridor by late
day. Not expecting any severe storms, but will again have to watch
burns scars for a brief heavier cell and potential for some higher
flows.
.LONG TERM...(Tuesday night through Monday)
Issued at 323 PM MDT Mon May 31 2021
...Afternoon and evening thunderstorms possible over the mountains
throughout the next week, and possible over the plains on Tuesday,
Thursday, and later in the upcoming weekend...
Tuesday evening through Wednesday...
The trough axis will finally begin to push south of the area later in
the day on Tuesday with just some remaining showers and
thunderstorms that have developed earlier in the day to be moving
towards the southeast and out over the plains later in the
evening. The U/L low over northern Mexico will eventually detach
itself and become cut off from the trough, which will subsequently
allow it to begin to fill and shift further eastward on
Wednesday. A jet maxima upstream over the Dakotas, and a sharply
positive tilted axis, will put southeastern Colorado in the
divergent quadrant, so thunderstorms look to develop over the
mountains during the afternoon on Wednesday as well. Models do
also show the CWA being in the convergent quadrant later in the
evening as the jet maxima shifts further south, and therefore this
should help to hinder further thunderstorm development over the
mountains towards the evening hours on Wednesday, with all other
locations in the CWA remaining dry. Thunderstorm development with
little upper level shear being relatively weak will keep many of
the storms remaining nearly stationary and this could bring about
a flash flooding concern for burn scars. It will be quite warmer
on Wednesday as well, with temperatures returning to right around
the seasonal average for most locations, especially over the
plains where it will be mostly clear throughout the day. Some low
80s will return to the lower Arkansas River Valley by Wednesday
afternoon.
Thursday through Friday...
The deterministic models and ensembles have been consistent with the
development of a well amplified ridge building back back in over the
entire western region with much warmer temperatures returning,
slightly above the seasonal average for many locations. The U/L
cutoff low off the coast of Baja California will begin to propagate
eastward over northern Mexico, and this will help to feed up a
substantial amount of mid level moisture from the south over the
region due to this and keep the instability around for this reason.
Coupled with this, there will be some U/L diffluence aloft moving
over the region, therefore, there will still exist the chance of
afternoon and evening thunderstorm development over the mountains
and a slight chance over the plains as well on Thursday. For Friday,
the cutoff U/L low remaining on place to the southwest and still
continuing to influence the CWA with some mid level moisture
advection from the south and afternoon instability providing the
lift needed for some storms over the mountains again, and a slight
chance over the most southern plains in the CWA as the lower level
flow switches back to southeasterly and brings back in higher
dewpoints. Temperatures will continue to warm as the ridge becomes
more amplified, with most locations being above the seasonal average
temperature for highs by Friday.
Saturday through Monday...
The ridge will begin to break down on Saturday, as all models allude
to a long wave trough upstream over the northwestern US beginning to
deepen slightly and progress eastward and towards the region, this
will allow for the mid level flow to return back to southwesterly
and also cause more U/L diffluence aloft to be present over the
region for both days as the long wave trough becomes nearly
stationary and only slightly deepens. Due to this, thunderstorms
developing over the mountains in the afternoon could move out over
the plains later in the evening. Surface winds will also pick up out
of the southwest and become rather strong and gusty for most
locations, especially out over the southeastern plains. The
troughing to the northwest will also allow for temperatures to cool
back down to right around the seasonal average for most locations by
Sunday, although with the adiabatically downsloping and drying
winds, the plains will still be very warm on Saturday through
Monday, with high temperatures reaching into the low 90s over much
of the plains, and even low 80s for parts of the San Luis Valley.
There are going to be two upper level lows associated with the large
longwave trough over the northwestern US by Sunday, and the
deterministic models do slightly differ on the location of these, as
well as the amplification of the trough, with the GFS showing the
secondary low causing the trough to deepen more significantly than
what the ECMWF is displaying for Sunday. The models also differ with
the displacement of cut off U/L low as it gets absorbed back into
the subtropical jet, with the ECMWF having the position of this
being further to the south. Therefore, there could either be
increased southwesterly flow for Sunday and on into Monday with a
better chance of thunderstorms over the mountains and over the
plains into the evening hours, as shear values will be stronger, and
more moisture flow from the southeast will be present with the
troughing over Texas to the south being further north as the GFS
model suggests. Or if the troughing over the northwest does remain
further to the north and the U/L trough in the subtropical jet over
Texas remains further to the south, only the mountains will be a
slight chance of afternoon thunderstorms and the plains will remain
fairly dry. The strong troughing with the GFS also has much of the
mid levels drying out by Monday with strong and gusty surface winds,
whereas the ECMWF keeps the southeasterly flow around on Monday with
a better chance of afternoon thunderstorms, mainly over the
mountains. It is still too far out to know which model is going to
prove to be more accurate, but it is worth taking note at how much
they begin to differ at this point in the latest runs, and will be
something worth checking for consistency between the two over the
upcoming days ahead.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 323 PM MDT Mon May 31 2021
At KALS, still a risk of chance of showers and thunderstorms into
the evening, with some brief periods of MVFR cigs/vis possible under
any heavier showers. Clouds slowly clear overnight, with a low risk
of some patchy/short-lived ground fog around sunrise. On Tuesday,
VFR with a chance of afternoon tsra after 20z.
At KPUB and KCOS, cigs becoming MVFR again into this evening, with
rain showers persisting until 03z. Rain chances decrease after 03z,
with some clearing possible after 09z as drier nw flow develops. If
we clear quick enough, there may be some areas of ground fog and IFR
vis around sunrise as low levels stay moist with recent rainfall,
though won`t include in either taf at this point. On Tues, VFR with
a chance of afternoon tsra, especially at KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 10 PM MDT this evening for COZ072>075-
077>080-087.
&&
$$
UPDATE...GARBEROGLIO
SHORT TERM...PETERSEN
LONG TERM...STEWARD
AVIATION...PETERSEN