Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/13/21
Area Forecast Discussion
National Weather Service Amarillo TX
629 PM CDT Sat Jun 12 2021
There is still some uncertainty about the potential for some
thunderstorms to make it into the Oklahoma and Texas Panhandle
from New Mexico. Main timing will be from about 02Z for KDHT, 04Z
for KGUY, and 06Z for KAMA if they are to be impacted. Have VCTS
in the TAF as confidence is still not very high if these storms
will maintain themselves or how wide spread they will be. If
thunderstorms do make it into the area this could create concern
for LLWS even if they are up to 5 miles away. Surface winds will
be out of the east to south around 5 to 15 kts, without
interference from outflows. CIGs should also remain above 9k ft
outside of any active thunderstorm.
.PREV DISCUSSION... /Issued 349 PM CDT Sat Jun 12 2021/
SHORT TERM...Tonight through Sunday Night...
H5 ridge axis extends from NRN Mexico into W Texas. Two subtle
ridge riding S/WVs can be seen in WV imagery in NRN NM and ERN AZ
and these are forecast to cross the region through the overnight
hours. The low level flow has returned to a more easterly
direction behind yesterdays front which is now located near a
Hereford Wichita Falls line, but will slowly lift and become more
diffuse through the night allowing winds to turn more SE.
Abundant low level moisture remains near and north of the boundary
and Tds are in the 60s with even some low 70s. Models agree that
H7 moisture advection has been occurring through the day with an
H7 theta-e ridge setting up near the WRN Panhandles. MLCAPE is
around 2500-3500 J/KG and the SPC RAP shows an impressive
3000-4000 MLCAPE by 01 UTC. While this seems high, it should be
noted that the 12Z sounding showed observed MLCAPE of just over
4000 J/KG which might be a record for the station! Effective bulk
shear is forecast to the be 30-35 tonight while the 0-3km helicity
increases to 200-300 with the help of a 30 kt LLJ. This all seems
to be setting the stage for a TSTM event and assoc severe chcs
with discrete cells possible early in the evening possibly
congealing into an MCS, HOWEVER there is one major caveat - there
is a cap.
While all the momentum was towards the more agressive models 18-24
hours ago, that has come to a screeching halt since then and
models have reverted to extremely different solutions regarding
how tonight will play out. Although the GFS remains extremely
agressive (and persistent), am somewhat dubious of this solution
given what appears to be convective feedback that significantly
strengthens the S/WV over the WRN Panhandles before it crosses to
the east. The FV3 Hi-res is one of the more agressive CAMs (GFS
influence?) and SPC HREF is relatively excited as well with
developing an MCS, but HRRR, NAM and others are not (HRRR not at
all). SPC has expanded the SLT risk through the day and it now
includes the entire WRN Panhandles (including a hatched area for
wind west), but there is still significant uncertainty given huge
spread in model guidance that ranges from an MCS impacting much of
the area to nothing holding together vs the cap and very little
or nothing happening. Current forecast is closest to the TTU WRF
which is a nice compromise solution. Forecsat is showing SCT
TSTMs in the west this evening (40-50% coverage) and lesser
coverage in the east as things weaken (20-30%). There would be a
threat for large hail and damaging wind and and a very low tornado
potential in this case. If the most aggressive CAMs verify, a
significant MCS would provide even higher wind and heavy rainfall
threat which is why SPC is also highlighting a significant wind
threat (hatched area) in the SWODY1.
H5 ridge builds north towards the Four Corners with mid level
flow becoming more NNW on Sunday. This flow regime does not favor
NM mountain convection crossing the border, but CAPE remains very
high and wind shear is sufficient that we can not rule out
influence from mountain generated storms further north than normal.
S/WVs riding this ridge also could cause cap to break allowing
isolated storms to form locally. Without presence of a boundary to
provide low level forcing, POPs have been limited to SLT CHC
tomorrow and tomorrow night but are above the NBM forecast POPs
which are less than 15 across the board.
Even though we are not seeing heat advisory level temps or heat
index, we have received word regarding heat related issues
occurring in the Canyon (heat index near 102 there). These
dewpoints are extremely high for the area and it is apparent, we
are not used to it.
LONG TERM (Monday through Friday)...
Overall, pretty quiet forecast in the extended. Seasonable
temperatures are forecast with mostly dry conditions. Friday is
our next best shot at seeing rainfall. High temperatures will be
mostly in the 90s next week with a few locations flirting around
On Monday, the H5 high will be centered over the Four Corners
region, and will sit over in this general area for several days
before eventually flattening out by the end of the work week.
This will result in a northwest flow pattern aloft. This pattern
is pretty typical for summer time convection here in the
Panhandles, and there will be a chance for thunderstorms to come
off the higher terrain to the west. There is also a chance for a
cold front to makes its way into the region, but models differ a
lot on the southward progression. The GFS is pretty aggressive
bringing it all the way into the Panhandles. If this comes to
fruition, we will have small perturbations within the northwest
flow which may interact with the cold front. This could result in
widespread rainfall. However, the GFS seems to be the outlier here
with several other models holding the front up in Kansas. We will
have to watch how this trends going forward. Otherwise, the long
term is pretty quiet with lots of sunshine and relatively light
Area Forecast Discussion
National Weather Service Cleveland OH
1001 PM EDT Sat Jun 12 2021
Weak low pressure and an associated cold front will slowly move
east across the area tonight through Sunday. High pressure will
briefly build across the region Sunday night before another low
and a cold front moves southeast across the region Monday.
.NEAR TERM /THROUGH SUNDAY NIGHT/...
1000 pm update... No significant changes were needed to the
ongoing near term forecast this evening and overnight.
The cumulus field south of the lake breeze remained benign
through the afternoon. Regional radars showed isolated
thunderstorm complex over northern Indiana and just northwest of
Detroit. HRRR show more convection moving across Michigan and
northern Ohio after midnight. Afternoon package captures this
feature with some weakening after midnight.
The activity over northern Indiana is worth watching. As this
activity and upstream cold front progresses east overnight,
activity should continue to weaken and become more
isolated/scattered, with slight chance pops progressing eastward
across the area overnight.
The cold front will push through the area on Sunday.
Destabilization ahead of the front will support another round of
showers/storms developing by the afternoon hours, and the impact
on the local area will be contingent on the speed of the front.
Model consensus shows the bulk of any destabilization and
associated convection occurring just east or on the eastern
periphery of the forecast area tomorrow afternoon. Upwards of
2000 j/kg SBCAPE may build into the far eastern part of the area
before the front moves through, but currently thinking the bulk
of the severe threat and convective activity will be just east
of the area. High pressure will briefly build across the area
late Sunday through Sunday night, although rain chances may
sneak back into the northwest part of the area late Sunday night
as a stronger wave quickly pushes southeast through the Great
Lakes. Highs on Sunday will again be in the low to mid 80s
across the area.
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
An upper-level trough will deepen as it moves east across the
Great Lakes Monday and Tuesday and a steep ridge begins to
build east into the Plains. Lingering moisture will provide
sufficient instability for shower and thunderstorm development
across the area late Monday morning through early Monday evening
and any precip chances should quickly diminish Monday night as
dry air begins to build east over the area. Temps will be in
the 70s across NW PA/NE OH and the upper 70s to low 80s across
NW OH. Although drier air will manage to seep in from the west
by Tuesday, there may be just enough moisture and instability to
support a slight chance of isolated diurnal showers and
thunderstorms during peak heating Tuesday afternoon. Otherwise,
Tuesday will be quiet with highs in the 70s to near 80 degrees
in the northwestern reaches of the CWA.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The start of the long term period will be characterized by dry
weather as weak cold air advection develops over the area on
Wednesday. Temperatures in the 70s with dew points in the 40s
will provide some relief from the recent heat and humidity
through Thursday, although temps may creep into the 80s in NW OH
Thursday as a ridge builds over the area from the southwest.
Temps will briefly increase Friday, with highs climbing back
into the 80s. The next significant chance of rain will arrive as
a shortwave moves across the area Friday and a cold front may
skirt across the area Saturday. Depending on the timing of the
cold front, temperatures may fall back into the 70s on Saturday.
.AVIATION /00Z Sunday THROUGH Thursday/...
VFR conditions are expected through most of the forecast period.
There is an outside chance of SHRA/TSRA after 00Z due to
approaching convection over northern Indiana. Otherwise, conditions
will be dry through the period. Some MVFR to potentially IFR
cigs/vsby may develop at KCAK, KYNG, and KERI after 06Z tonight
before weak cold front cross the area near the end of the
period. Light/variable winds are expected overnight becoming
northwesterly on Sunday.
Outlook...Non-VFR possible in thunderstorms Sunday morning into
mid afternoon, mainly at eastern terminals. Non-VFR also
possible Monday afternoon/evening in showers/thunderstorms.
Northeasterly winds will persist over the lake through tonight, but
should remain below 12 knots. Flow will become northwesterly Sunday
as a trough crosses the area and onshore flow should persist
through the first half of the week. Winds may increase to 15 to
20 knots Tuesday evening through Wednesday morning, and a Small
Craft Advisory may be needed if onshore wind speeds trend higher
than the current forecast. Otherwise, no marine headlines are
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
638 PM CDT Sat Jun 12 2021
.DISCUSSION...(This evening through Saturday)
Issued at 310 PM CDT Sat Jun 12 2021
Overall...a fairly nice day across the local area with sunny
skies, seasonably warm temperatures and low dew points.
In the upper levels of the atmosphere...high pressure across the
the desert southwest is expected to expand northeastward over the
next few days...with southerly flow at the surface gradually
increasing dew points across the area. This will result in a rapid
return well above normal temperatures...with lower 90s returning
tomorrow...gradually increasing to mid and upper 90s by the middle
of next week. A weak cold front could then bring a slight cool
down late next week.
At the same time...multiple disturbances are expected to round the
top of the ridge and clip the local area...bringing multiple
small chances for thunderstorms to the region.
The overall best chance for thunderstorms appears to be with an
MCS rounding the ridge Sunday night...bringing a fair chance for
thunderstorms to areas west of Highway 281...with the main focus
expected to be just west of the outlook area where a marginal
risk for severe weather exists Sunday night. Given that the
forecast was dry for this time period just 24 hours
ago...confidence isn`t the highest in precip locally...and capped
chances at 40 percent across our western counties. That
said...more and more models are capturing this MCS...with the
NAMnest, NAM and HRRR all clipping the western half of the local
area Sunday night. If strong or severe thunderstorms do impact our
area...winds appear to be the primary concern Sunday night...with
a lesser threat of hail...although that threat is non-zero given
the elevated instability in place across the local area.
Thereafter...additional multiple disturbances will round the ridge
and bring small chances for thunderstorms again Monday night,
Thursday night and Friday night. These chances appear a bit more
spotty than Sunday night...and are much less confident. So
overall...expect warm temperatures to return with multiple small
chances for thunderstorms...although it is very possible parts of
the local area will not receive any precip over the course of the
next 7 days.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 636 PM CDT Sat Jun 12 2021
No significant weather.
VFR conditions will prevail through the period with hardly a cloud
in the sky. Winds will gradually veer from ESE to S and generally
remain between 5-10kt. Confidence: High.
Area Forecast Discussion
National Weather Service Goodland KS
952 PM MDT Sat Jun 12 2021
.SHORT TERM...(This evening through Monday night)
Issued at 231 PM MDT Sat Jun 12 2021
500mb RAP analysis and satellite imagery showed west to southwest
flow over the High Plains, with a broad ridge spread over the CONUS.
An area of high pressure could be seen over west Texas and southern
New Mexico. Sunny to mostly sunny skies were observed across the
region this afternoon, with fields of cumulus clouds along and south
of Interstate 70. At 2 PM MT, southerly winds were at 10 to 15 mph,
gusting around 20 mph, and temperatures were mainly in the 80s.
For tonight, the upper ridge begins to amplify along the Rockies as
upper high pressure moves further into the Desert Southwest.
Temperatures fall into the low/mid 60s under mostly clear to partly
cloudy skies. A disturbance rotates around the ridge overnight,
generating storm chances south of the area. There will be a brief
window between roughly 3 AM and 7 AM MT that a few storms could
develop in the southeastern portion of the region (generally Logan
and Gove counties), but severe weather is not expected.
On Sunday, the ridge builds along the Rockies and Plains as a trough
deepens along the west coast. This results in the start of a warming
trend, with highs in the upper 80s and low 90s. Meanwhile at the
surface, high pressure gradually pushes eastward. While the ridge
axis straightens along the Rockies midday, moisture increases and a
few storms could fire off the Front Range by the late afternoon. As
this activity progresses southeast, additional storms may develop
along a cold front situated in northern Nebraska. This second area
of thunderstorms is shown to track east southeast through western
Nebraska, forming a cluster, and crossing the region late Sunday
night into early Monday. At this time, confidence in storms
occurring is low. However, shear of 20-35 knots, as well as moderate
lapse rates and instability, suggest that a few strong to severe
storms are possible if storms do in fact occur. The favored area for
severe weather is generally west of a line from McCook, NE to Gove
City, KS. Damaging winds are the primary threat, with a lesser
threat of large hail. With PWATS in the 1 to 1.5 inch range, would
need to monitor for heavy rainfall as well if storms develop. Again,
confidence is low. Otherwise, temperatures fall into the low to mid
60s once again.
Storms may linger into Monday morning, followed by decreasing cloud
cover and sunny skies. Northwest flow prevails on the eastern side
of the upper ridge which remains centered along the Rockies.
Temperatures continue to warm, reaching the low 90s region-wide.
Another disturbance rotates around the ridge Monday night,
generating precipitation chances just to the northeast of the
region. Have kept the forecast dry for now thinking the ridge will
suppress activity, but will monitor for the potential that chances
need to be brought south. Lows range in the 60s.
.LONG TERM...(Tuesday night through Saturday)
Issued at 234 PM MDT Sat Jun 12 2021
Hot, warmer than average temperatures around the century mark,
will dominate the Long Term period from Tuesday through Thursday
prior to the passage of a cold front on Friday that brings
temperatures back closer to normal for this time of year on
The high amplitude upper ridge over High Plains region on Tuesday
moves into the central U.S. on Wednesday as it begins to flatten
in response to the upper low center moving eastward across
southern Canada. While the upper ridge may flatten, the large
upper high over the western U.S. remains centered over the
4-corners region through Thursday. As the low continues across
Canada with a series of individual short waves circulating through
the Upper Midwest and Great Lakes region, a weaker ridge
reamplifies briefly further west over the U.S. Weakly northwest
flow aloft over the central High Plains will usher in a series of
short waves aloft that move east of the Rockies and across the
High Plains late each day as well as a cold front that moves
through the region early Friday to help bring down the hot
temperatures by next weekend.
With the upper ridge and high center over the region, temperatures
will remain hot with highs in the mid 90s to the century mark on
Tuesday through Thursday with some relief to come on Friday behind
a cold front. Highs Friday will range from the mid 80s to lower
90s with mid to upper 80s on Saturday. Relative Humidity values
are not expected to be as high as they have been over the last
week, so the Heat Index values will stay close to the ambient air
temperatures through the hottest days.
Dry conditions are expected through the day on Thursday with a
slight chance of thunderstorms showing up late Thursday as a weak
short wave trough moves through the upper flow ahead of the cold
front expected early Friday. There is a slightly better chance of
thunderstorms on Friday and Saturday afternoon and evening as
slightly stronger short wave troughs move across the region.
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 950 PM MDT Sat Jun 12 2021
From a pattern recognition standpoint.. increasing moisture and
SE-SSE low-level flow would suggest some potential for sub-VFR
ceilings AOA sunrise Sunday morning (mainly at the GLD terminal)..
though confidence is low. Otherwise, VFR conditions are
anticipated to prevail through the TAF period.. with SSE to SE
winds at 10-15 knots.. increasing to 15-20 knots Sunday afternoon.
Thunderstorms.. perhaps severe.. may approach the region from the
north near the end of the TAF period (~06Z Monday).
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
851 PM CDT Sat Jun 12 2021
Updated for evening discussion.
The potential for any severe weather has ended. However, an outflow
boundary in western Alabama pushed convection into east central
Mississippi. Have increased pops and cloud cover over our eastern
most counties the next several hours to account for this activity
which is not expected to push much farther west before
dissipating. Satellite imagery shows only a few high thin cirrus
elsewhere over of our CWA. /22/
Prior discussion below:
Tonight and Sunday: Convection has been slow to develop in the south
as low level inversion has yet to be overcome in most places. To
the north, strong subsidence in the wake of morning MCV passage
has suppressed the CU field through much of the day with visible
imagery only now beginning to show some. Based on latest satellite
trends, the best convective potential going into the evening will
be over the southeast.
With the ridging continuing in the west and northerly mid level
flow over the area, not much airmass change will occur through
Sunday. While the low level inversion will drastically limit
convective potential in the west, ridging aloft over the mid MS
valley may begin to limit shortwaves/convection dropping south in
the flow. The HRRR seems to indicate this with little convection
in recent simulated runs. /GG/
Monday through Saturday:
Starting off the new work week, the flow aloft will become northerly
as a stout ridge over the Rockies amplifies and tilts eastward. A
sequence of shortwave troughs rounding the ridge axis and diving
south will reinforce a generally drier pattern, while at the surface
a weak "cold" front will be marked by lower dew points and higher
surface pressure. POPs will be focused along the Gulf Coast in the
first half of the week, trending to below mentionable values by
Wednesday and Thursday. Guidance remains in fairly decent agreement
with this overall pattern, and a consensus blend of forecast
elements looked reasonable. Before the front arrives, daytime max
temps in the lower to mid-90s can be expected on Monday and Tuesday.
Combined with lingering humidity, dangerous heat conditions are
possible mainly south of I-20 on Monday and could develop again on
Tuesday. For the back half of the work week, the upper-level flow
looks to break down some as the axis continues to shear and tilt to
the east and a deeper trough dives into the Upper Midwest region.
While all this is going on in the westerlies, a broad area of
showers and storms over the Bay of Campeche in the southwestern Gulf
of Mexico should continue to wobble in that vicinity for a few days
before slowly advancing northward. These broad systems are hard to
predict in fine detail, but the environment will generally support
some organization over the next few days. A Tropical Depression is
possible to develop within the circulation, and that potential will
have to be monitored. It is still too early to pin down any
potential impacts around the central Gulf Coast region, but some
increased chance for heavy rain and stronger winds will exist along
the Gulf Coast near the tail end of the current 7-day forecast. Stay
tuned for updates throughout the week, especially if traveling along
the Gulf Coast late this week and early next week. /NF/
00Z TAF discussion:
Radar showed a band of TSRA in western Alabama that may spread
west and come in vcty of MEI by 02Z. This activity is expected to
remain se of GTR and dissipate before reaching PIB-HBG. Otherwise,
VFR conditions are expected to prevail through Sunday afternoon.
There is the potential for TSRA to come in vcty of the eastern
and cntrl TAF sites by 21Z Sun. /22
.PRELIMINARY POINT TEMPS/POPS...
Jackson 74 92 74 93 / 8 45 15 21
Meridian 72 92 72 92 / 75 42 14 24
Vicksburg 75 93 75 93 / 8 38 15 19
Hattiesburg 74 93 74 93 / 14 43 19 44
Natchez 75 92 74 92 / 9 38 19 29
Greenville 74 93 74 91 / 9 33 14 13
Greenwood 73 92 73 92 / 12 48 14 13
Area Forecast Discussion
National Weather Service North Platte NE
653 PM CDT Sat Jun 12 2021
.SHORT TERM...(This evening through Sunday night)
Issued at 320 PM CDT Sat Jun 12 2021
Moisture across wrn KS this afternoon is progged to return north
into wrn Nebraska late tonight and Sunday afternoon. This is the
result of sfc high pressure across ern SD/ern Neb moving south and
east into Missouri by Sunday afternoon. The models are in good
agreement showing sfc dew points across wrn Nebraska rising into the
low to mid 60s Sunday afternoon. The short term model blend backed
by the HREF, NAM12 and NAMnest all show a fairly robust area of
outflow dominant thunderstorms forming early Sunday evening. The
resultant cold pool from the outflow and moist southerly inflow
would appear to drive storm development south and east through swrn
and scntl Nebraska.
POPs for Sunday evening are set at 40 percent. This is less than the
short term model blend which suggested likely POPS of 60-70 percent.
There a few factors which could limit convection. One limiting
factor is the lack of synoptic scale forcing. A weak subtropical
disturbance across nrn AZ this afternoon should lift north through
Colorado/WY tonight and then move east Sunday as it rounds the top
of a building upper level ridge centered over NM this afternoon. The
forcing from the disturbance appears to be very modest. Another
potential problem is the models may be too strong and too fast with
moisture return. Lastly, the GFS, ECM and RAP models which are
different from the convection allowing models listed above, generate
much less convective coverage.
On the other hand, there is an excellent focus for storm
development. A Pacific high pressure system and associated sfc
cold front should drift through SD late tonight and be located
near or just north of the SD/Neb border Sunday afternoon.
Temperatures aloft at h700mb are also fairly cool, near 11C,
suggesting a weak cap will be present. Given the weak winds aloft,
20kts at h500mb, the threat of supercell development is low. The
bulk effective shear, the result of strong inflow, is 35 to 40 kts
and BUFkit suggested briefly severe storms which would quickly
evolve into a multicell system. SPC suggested a marginal or 5%
severe weather risk Sunday evening.
.LONG TERM...(Monday through Saturday)
Issued at 320 PM CDT Sat Jun 12 2021
Northwest flow aloft develops tonight and continues through Wednesday.
The GFS suggests the potential for storms to develop off the
Black Hills or the Big Horns Monday which would certainly be
steered through ncntl Nebraska Monday night. Chance POPs are in
place for this event. The ECM and NAM are mostly silent with storm
development so forecast confidence is on the low side.
The rest of the forecast contains isolated thunderstorm chances at
times. The notable feature of the extended forecast is
temperatures in the mid and upper 90s Wednesday and Thursday. The
models are in good agreement warming h700mb temperatures to around
17C both days. Although mixing heights would probably remain
below that level, temperatures should rise well into the 90s
Wednesday- the warmest day. A Pacific cold front moves part way
through wrn and ncntl Nebraska Thursday and just srn Nebraska
heats up. A check on heat indices indicates Wednesday will be a
potential Heat Advisory day but only marginally so with dew points
in the lower 60s.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 648 PM CDT Sat Jun 12 2021
VFR conditions will prevail across western and north central
Nebraska tonight into Sunday. Winds will generally be around 10
kts or so from the south to southeast. Some chance for
thunderstorm development late Sunday afternoon across northwest
Nebraska. Those storms would then move southeast across western
Nebraska Sunday evening.
Area Forecast Discussion
National Weather Service Pueblo CO
639 PM MDT Sat Jun 12 2021
Issued at 616 PM MDT Sat Jun 12 2021
...TORNADO WARNING CURRENTLY IN EFFECT FOR NORTHERN CENTRAL LAS
ANIMAS COUNTY, DOPPLER RADAR INDICATED ROTATION WITHIN THIS STORM,
WHICH IS NEARLY STATIONARY AND SLOWLY MOVING SOUTH. THIS STORM IS
CAPABLE OF PRODUCING A TORNADO, ALONG WITH 2.5 INCH HAIL, AND
WINDS IN EXCESS OF 70MPH. SEVERE THUNDERSTORM WARNING IS ALSO IN
EFFECT FOR NORTHWESTERN LAS ANIMAS COUNTY, SOUTHWESTERN OTERO
COUNTY, AND SOUTHEASTERN PUEBLO COUNTY...THIS STORM IS CAPABLE FOR
PRODUCING HAIL OF 1.5 INCHES IN DIAMETER IN WIND GUSTS OF 70MPH.
PoPs and QPFs have been updated to account for newly developed
areas of convection.
.SHORT TERM...(This evening through Sunday)
Issued at 254 PM MDT Sat Jun 12 2021
Some cumulus clouds are forming over the Raton and Southern Sangres.
meanwhile, the far southeast plains are seeing dewpoints in the mid-
60s. Latest HRRR runs seem to be drying things out but strengthening
southeast winds and high dewpoints suggest otherwise...
Rest of Today and Tonight...
The upper ridge will continue to build in over the region through
the rest of today and tonight, keeping flow west-southwest aloft and
advecting more dry air into our mid-levels. Along with that, surface
flow over the southeast plains will be from the southeast, which
means the lower levels will be getting more moisture, which will
assist with instability; dewpoints in the low-mid 60s are already
present in Baca County.
The moist southeast surface flow will be enhanced orographically,
and with the dry mid-levels supporting near-dry adiabatic lapse
rates, most of the models are in agreement of convection initiating
over the Raton Mesa and southern Sangre de Cristo Mountains by 3-4PM
this afternoon. CAPE will be sitting between 1000-1500 J/kg as well,
and storms will likely have few problems breaking any cap. Given
pretty potent-looking inverted-V soundings, and considering the
lapse rates, strong wind gusts of over 60 mph and hail up to 1
inch in diameter will be possible with these initial storms.
As storms head further east towards the Kim area between 4-6PM, the
environment will start looking a bit more favorable the further east
the storms move. CAPE around Las Animas County is expected to sit
between 1500-2000 J/kg, with bulk shear topping off over 30 knots.
Overall, shear and instability will be more supportive of stronger
storms, and hazards in this area will likely increase to 70 mph wind
gusts and 1.5 inch hail as possible threats. Hodographs appear to
still be pretty straight, and although there is some SRH present in
the environment, the tornado threat is relatively low, although
still non-zero given the shear profile.
Finally, storms will head towards Baca County after 6-7PM, where
there will be higher CAPE (2000+) along with better shear and
increased environmental helicity. The wind and hail threats will
continue, but with the increased parameters there is the chance for
an isolated tornado to form. Severe thunderstorm chances diminish
greatly after 8PM or so, but a few weaker residual storms could
stick around for a few extra hours.
Confidence in storms reaching Baca county has fluctuated over the
last several hours, with some short-term models (looking at the HRRR
specifically here) have been coming in dry for the last few runs,
suggesting that storms may have a problem breaking the cap out there
and accessing the stores of instability available. Will monitor
going forward. While the ingredients for stronger storms are still
present in Baca County (CAPE, shear, helicity, etc.) there is rising
confidence that storms may unable to break that cap. So overall,
while confidence in longer lived storms out east has decreased, if
storms do manage to persist out there, they will likely be strong to
severe in nature.
Other than the main severe threat, there is a low-end chance for
some weaker storms to form near Pueblo and the highway 50 corridor,
where the main concerns would be gusty winds. Temperatures are
expected to be above average once again, with high-80s to low-90s
forecasted over most of the area. Lows tonight will dip into the 40s
over the valleys, but over the plains things should stick around the
On Sunday, a disturbance to the flow will pass through the upper
high over our area, bringing some increased ascent to the I-25
corridor and adjacent areas, increasing chances for more widespread
thunderstorms during the afternoon hours. The wind shear setup will
be similar to today`s with moist southeast flow at the surface
contributing to higher moisture content, while at mid levels more
westerly flow will advect in dry air and assist in steepening mid-
level lapse rates. Bulk wind will also increase from today, hitting
30-45 knots in places over the southern I-25 corridor. CAPE should
be more widespread thanks to the influx of 50s-60s dewpoints
expected at the surface, so most of I-25 will be sitting near 1500
J/kg by Sunday afternoon. However, a surface inversion and decent
amounts of CIN could limit not only thunderstorm extent but also the
potential strength, so these conditions will have to be watched
going forwards. Should a thunderstorm overcome these two factors and
reach its full potential, it would likely become a supercell,
capable of producing large hail, severe outflow winds, and a tornado
.LONG TERM...(Sunday night through Saturday)
Issued at 254 PM MDT Sat Jun 12 2021
...Heating up with another uptick in thunderstorms late week into
Thunderstorms will continue into the evening hours across the
southeast plains as one or more convective clusters develop across
the plains as the low level jet intensifies. With MlCAPE around
2000 J/kg and deep layer shears around 30-40 kts, one or two severe
storms will be possible into the evening hours. LCLs look a little
higher than the previous day, so still think primary risks will be
large hail and damaging winds into the evening hours. However with
such stout CAPE aloft, and decent low level shear can`t rule out
a brief tornado. The Palmer Divide and Raton Ridges tend to be the
higher probability locations due to terrain induced boundaries
where resident surface vorticity can get stretched. So although a
low probability event, it will still bear close watching. Best low
level moisture looks to be across the Palmer Divide right now, so
that may be the higher probability location. High res models
drive a westward propagating outflow boundary into southeast CO
overnight originating from convection in KS and have maintained
some isolated pops across far eastern areas to account for the
potential of thunderstorms to linger past midnight.
Monday...the upper high will continue to build northward over the
Rocky Mountain region and temperatures will heat up once
more...particularly out west. Nam12 maintains some higher dew
points across the plains vs other models which do not appear to
resolve the Sunday night convection/outflow boundary. Deep layer
shear weakens with the upper high overhead but with upslope flow
can`t rule out an isolated thunderstorm across the southeast
mountains/adjacent plains on Monday. Almost due southerly storm
motions should keep any isolated activity tied to the mountains, as
the southeast plains appear capped for now. GFS is more robust
with mixing out the surface dew point in spite of southeast low
level flow and therefore keeps all of southern CO dry. Plan to
keep some isolated pops in and near the southeast mountains for
now and will need to watch how this evolves. With high LCLs,
around H6, gusty winds and lightning would be the primary storm
Upper high stays locked in over the 4 corners region through mid to
late week, gradually moistening in the mid and high levels as
recycled moisture from thunderstorms across the western U.S. get
entrained within the upper high. Southeast plains may see periodic
intrusions of low level moisture from westward propagating
boundaries originating from central plains MCSs...with GFS
advertising the next one for Monday night. However low level
moisture is advertised to mix out each afternoon with temperatures
soaring to around 100 across the plains again through mid week.
Overall, will keep isolated thunderstorms in the forecast each
day mainly for the mountains, with an uptick towards mid to late
week as mid and high level moisture increases.
An upper trough to the north will clip through the the northern high
plains, shifting the upper high westward and allowing a cold front
to drop through the southeast plains late in the week. This will
bring a cool down for Friday and another potential uptick in
thunderstorms across the southeast mountains and adjacent plains
into next weekend. With northwest flow over the region, we could see
another round of strong to severe thunderstorms along the I-25
corridor if low level moisture return is sufficient Friday and
Saturday...as southeast surface winds beneath northwest flow aloft
is a classic severe weather pattern for southeast CO. -KT
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 254 PM MDT Sat Jun 12 2021
VFR conditions are expected at KALS, KCOS, and KPUB over the next 24
hours. There is a low chance that a thunderstorm could develop near
KPUB around 00-02Z tonight, but confidence is low enough to not
include it in the TAFs. If a storm were to form nearby, gusty,
erratic winds and MVFR conditions from heavy rain would be possible.
Overnight tonight KCOS could get some low clouds that could lower
flight category from cigs, but it will largely depend on how strong
the southeasterly flow gets later tonight, so left things at VFR for
now. Winds at KCOS and KALS will be gusty, up to around 25 mph, this
afternoon through around 03Z tonight.
Area Forecast Discussion
National Weather Service Blacksburg VA
720 PM EDT Sat Jun 12 2021
Expect one front to move south of the area tonight, while
another front sinks southeast to region by Monday morning. This
front will bring a return of less humid weather as high
pressure builds in to the Mid Atlantic region for the middle of
.NEAR TERM /THROUGH SUNDAY/...
As of 715 PM EDT Saturday...
Big decrease in rain and thunderstorm activity within the last
hour or so as instability wanes. Only a few remaining showers
along the western slopes of West Virginia, extending down to
northwest North Carolina. Expect most of this to continue to
diminish through the evening. Fog and low clouds still expected
to develop overnight and into the early morning hours.
As of 230 PM EDT Saturday...
Expect bands of showers/few storms across the west through this
evening then foggy overnight, followed by a few more storms Sunday...
High-res convective allowing models handling setup this afternoon
fairly well with corridor of deep moisture convergence and some
upper difluence from the Greenbrier Valley/Alleghanys south through
the New River Valley, into the NC mountains/foothills. The HRRR has
been so far doing the best with this, and hangs onto showers/few
storms into this evening in the same location. Downpours are limited
to shorts amount of time due to speed and size of cells, so at the
moment do not see a need for flash flood watch, but not out of the
question to have localized flooding, especially if storms train or
move slower over an urban area like Galax/Radford/Wilkesboro.
Convection wanes fast this evening to just showers then limited
coverage by 10pm, to nothing overnight.
Fog and low clouds are likely overnight as drier air aloft works in
while boundary layer/surface stay moist. Could see a dense fog
advisory for the mountains, but will let the next shift examine
parameters and see how we clear out if at all overnight.
Sunday, we will be a northwest flow aloft with upper divergence, and
limited upper forcing per models. At the surface a cold front works
from Ohio/KY Sunday morning slowly into the central Appalachians
mid afternoon. By late in the afternoon, models develop convective
induced vorticity across the Alleghanys. With a little more wind
speed aloft, a marginal risk for severe storms exists mainly
along/north of I-64 with best threat for severe storms further
north. Limiting factor could be the low clouds/fog early but models
showing more sunshine by midday, though the Nam is a little higher
on cloud cover.
Lows tonight will be slightly lower than this morning with lower to
mid 60s most places. Warmer Sunday with more sunshine, with 80s
areawide, except 70s higher elevations.
Forecast confidence in temperatures and wind are high, pops through
this evening high, but average on threat and coverage of storms
Sunday with best chance along/north of BKW-LWB-ROA.
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 230 PM EDT Saturday...
Chances of rain Sunday night...Monday and Tuesday drier...
A cold front passes overhead late Sunday and brings chances of rain
showers for the whole area, but showers are more likely for those
west of the Blue Ridge towards eastern WV. A cutoff upper low forms
over eastern Canada turning our upper flow to the northwest. This
advects cooler, dry, continental air into the Mid-Atlantic.
Temperatures will drop marginally, to near normal for mid-
June, but humidity will be less. More impactfully, chances for
showers on Monday and Tuesday will be low as there is no deep
moisture to tap into as there was last week. Any showers that
form up will be light and likely short lived.
With the drier air aloft, skies will clear up. Monday and Tuesday
will be sunny with highs in the 70s west of the Blue Ridge, 80s
east. It will feel more comfortable outside as dewpoints also drop
and relative humidities in the afternoons will be in the 40-50%
range. Lows will be in the 50s and low 60s both nights.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 230 PM EDT Sunday...
Quieter weather through the week, with a front approaching over
Drier air from northwest flow as well as surface high pressure will
keep the skies inactive for the second half of the week. The nights
could get rather cool, with lows on Wednesday and Thursday in the
mountains reaching down into the 40s. On Saturday another upper low
makes its way into eastern Canada, and brings with it an associated
surface low and trailing cold front. PoPs start to come back up
again on Saturday with the chance for some pre-frontal showers. Next
weekend will be the most active weather we`ll have seen since the
start of the week.
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
As of 715 PM EDT Saturday...
VFR this evening with most shower/storm activity beginning to
Cigs and vsbys get lower overnight thanks to a stable but moist
low level airmass. Could see dense fog at LWB/BCB/BLF, but
perhaps even LYH, but confidence is not high enough for LYH yet.
So looking at IFR or worse at all taf sites overnight.
Will see cigs/vsbys improve to VFR between 12-15z.
Another front pushes south for Sunday. Any storms on Sunday
will likely hold off til after 18z, and mainly northwest of a
line from BLF-BCB-LYH. Confidence is not high enough to mention
in the TAFs yet.
High confidence on poor cigs late tonight. Otherwise average
confidence for ceiling, visibility and wind.
Extended Aviation Discussion...
Mainly VFR into Thursday outside of any late night fog in the
mountains with high pressure settling in over the region.