Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/08/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
843 PM CDT Mon Aug 7 2023
.UPDATE...
Issued at 840 PM CDT Mon Aug 7 2023
Widely scattered shower/thundershower activity from earlier this
evening has been reduced to just a couple showers by Watertown.
Adjusted POPs earlier this evening to better match the activity
across the eastern CWA, but we should see that coming to an end
shortly. Otherwise, the rest of the forecast for the overnight
period is on track and aside from tweaks to sky grids, no other
noteworthy changes are needed.
&&
.SHORT TERM...(This Evening through Tuesday Night)
Issued at 225 PM CDT Mon Aug 7 2023
While most of the forecast area remains dry, we are seeing some
isolated to scattered rain showers pop up west of the Missouri
River this afternoon. These chances continue through the evening
with more chances again Tuesday afternoon/evening timeframe in our
southern area. Otherwise, temperatures will be pleasant at or
below average through the short term. EC/GFS ensembles along with
deterministic models agree on northwest flow at mid-levels this
afternoon into this evening as a weak shortwave moves in from the
west and continues southeast this evening. The high pressure
system that was over the area will push more south as well. This
wave is clipping parts of our western to south central CWA
bringing these rain showers due to weak lift from the wave.
Rap/HREF+CAMs indicate slight to chances of precip continuing
through this evening and decreasing after sunset. NBM had nothing
in the form of pops. So kept with the previous shift and have
15-35% pops around and west of the Mo River through this evening.
MUCape/MLCape remains pretty limited,(900 J/kg at most) and no
shear. So with some Cape, along with daytime heating and dew
points marginal(upper 50s), isolated thunder is possible along
with these chances of rain. HREF z>40 dbz paintballs backs this up
showing some pulse-type storms possible if enough vertical growth
(again this wave is pretty weak). No severe weather anticipated
today, however, mean wind is light so some of these showers/storms
could be slow moving/back building as PWAT values from west
central to south central SD is around an inch to 1.15 with RAP
soundings pretty moist at mid levels. (Quite less than what we saw
this past weekend).
Another mid level wave/sfc low, will push southeast across the
central CONUS Tuesday afternoon through Wednesday morning, with a
ridge building behind the low. Short term models/CAMS indicate
precip chances could clip our southern counties, mainly around and
south of I90, however, recent updates are now keeping pop chances
even further south than previous. Also, due to lack of forcing now
at 850/500mb, this should keep pops from forming well north of I90
as NBM has them further north. So with this and collaboration, I
took out these pops further north and left them around and south of
I90 which range from 15-40% with the highest just south of I90.
Instability remains low (at or under 1000 J/kg CAPE) with the higher
amounts staying well to our south. So with just enough lift, thunder
is possible again and no severe weather anticipated.
Average highs for this time of year range in the mid to upper 80s
and lows in the upper 50s to the lower 60s. With cooler 850mb temps
continuing, temps will remain at or below average as the spread in
the 25-75th percentile, per NBM, is only a few degrees tonight into
Tuesday. Overnight lows will range in the low/mid to upper 50s and
highs for Tuesday will be at or a few degrees warmer than today,
ranging in in the upper 70s to the lower 80s.
.LONG TERM...(Wednesday through Monday)
Issued at 225 PM CDT Mon Aug 7 2023
The main forecast challenge in the extended period revolves around
chances for precipitation, and possibly severe weather. The period
starts off with an upper level shortwave trough exiting the area and
northwest flow setting up. A brief period of ridging will occur
Wednesday night into Thursday morning before another, somewhat more
potent, shortwave trough slides across the area Thursday
afternoon/night. Northwest flow then sets up again and will be
dominant through the remainder of the period.
At the surface, high pressure will keep conditions quiet Wednesday
and Wednesday night before a frontal boundary tracks across the area
Thursday into Thursday night. In association with the aforementioned
shortwave trough, this boundary looks to be the focus for convective
development, possibly strong to severe, Thursday afternoon/evening,
particularly across the eastern CWA where a combination of MUCAPE
values in excess of 3000 J/kg and bulk shear of 30 to 40 knots will
be in place. High pressure settles in over the region Friday and
Saturday. Another frontal boundary will track across the area late
Saturday night and Sunday. Since this is at the tail end of the
forecast, will just continue to monitor for now for the potential
for strong or severe convection during that time period.
High temperatures will generally be in the upper 70s to upper 80s
through the period. Overnight lows will be in the 50s to lower 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 635 PM CDT Mon Aug 7 2023
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are forecast through the TAF period. There are a
few -SHRA across northeast SD currently, so will include VCSH for
KATY right at the start of the period, but expect this activity to
dissipate with the setting sun.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TMT
SHORT TERM...MMM
LONG TERM...Parkin
AVIATION...TMT
Area Forecast Discussion
National Weather Service Boise ID
827 PM MDT Mon Aug 7 2023
.DISCUSSION...A strong cold front (for this time of year) passed
through eastern Oregon late today and western Idaho early this
evening with showers and thunderstorms. Thunderstorms brought
heavy rain and small hail but storm motion was fast enough to
prevent widespread flooding. The Weiser River Basin had some
of the heaviest rains, and brief flooding did occur. At 8 PM
MDT a flash flood warning was in effect on a former burn scar in
the Boise Mountains northeast of Boise. Outflow winds from the
incoming thunderstorms defined the cold front, with peak gusts
around 50 mph. At 8 PM MDT the front was east of Mountain Home
and should reach the Jerome/Twin Falls area between 9 and 10 PM
MDT. Expect gusts from the west around 50 mph there also,
followed by showers and thunderstorms until around midnight.
High-res NAM and HRRR both show up to around .15 inch of
rainfall there after the front passes. Meanwhile, showers and
winds will decrease in western areas through the night. We will
update to add in patchy fog for the valleys Tuesday morning.
Tuesday should also be the coolest day of the week with gradual
warming and drying the rest of the week. Current forecast
already has this.
&&
.AVIATION...MVFR in precipitation, otherwise VFR. Scattered showers
and a few thunderstorms will produce heavy rain, gusty winds,
and locally small hail through through 03Z across the Treasure
Valley and Boise Mountains, and 05Z across the western Magic
Valley. Areas of wildfire smoke and blowing dust near
thunderstorms will locally reduce visibility. Patchy morning
valley fog expected in the Treasure Valley terminals and near
KBKE, KMYL, and KBNO. Surface winds: SW to NW 5-15 kt except NW
20-30 kt sustained near showers. Gusty and erratic winds up to
50 kt will blow out in front of thunderstorms in the Magic
Valley. Winds aloft at 10kft MSL: W-NW 15- 30 kt.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Wednesday night...Thunderstorm
activity will dissipate from west to east tonight as the upper
trough and cold front exit the region. Thunderstorms will bring
heavy rain, gusty winds, and possibly small hail. A flooding
threat does exist through early evening across e-central Oregon
and the w-central idaho mountains, though storms will likely be
short-lived which would limit storm totals. Strong winds are
looking more likely through the late evening as storm activity
over e-central Oregon generates cold outflow. High resolution
models are consistent in pushing gusty winds through Malheur
County and the Snake Plain through the evening with gusts 45-55
mph, though locally stronger winds are possible. Shower and
thunderstorm activity will transfer into the SW Idaho highlands
and western Magic Valley tonight, with the gusty wind threat
continuing. Loss of heating will diminish the threat for hail.
Drier conditions will develop over the region Tuesday and
Wednesday as westerly flow develops. A weak shortwave trough
tracking along the US/Canada border will spark a slight chance
of showers/storms on Wednesday. Otherwise conditions will
remain dry.
LONG TERM...Thursday through Monday...The period will start off
under a dry zonal flow for Thursday and Friday. Forecast models
are showing a weak trough setting up along the CA coast over
the weekend. Circulation around this low will push monsoon
moisture northward, crossing into far SE Oregon and SW Idaho
along the NV border over the weekend. Westerly flow will keep
the moisture confined to southern zones through Monday.
Temperatures near normal to end the week, warming above normal
for the weekend into next week.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
DISCUSSION...LC
AVIATION.....SA
PREV SHORT TERM...DG
PREV LONG TERM....DG
Area Forecast Discussion
National Weather Service Burlington VT
1047 PM EDT Mon Aug 7 2023
.SYNOPSIS...
Showers and embedded thunderstorms will become more widespread
tonight through Tuesday as low pressure tracks northeast of the
region through the St. Lawrence Valley. Heavy rainfall is likely,
and localized flash flooding remains possible. Some isolated showers
are possible Wednesday with drier weather returning for Wednesday
night into Thursday morning. On and off chances for showers is
expected thereafter through the weekend.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 1047 PM EDT Monday...Mesoscale details remain challenging
with regards to timing and placement of heaviest rain as
precipitation remains fairly scattered. Latest radar trends
suggest training showers over the western Adirondacks and a
large slug of rain is pushing northward near the Capital Region
of New York. Have increased QPF mainly in southeastern St.
Lawrence County for the current six hour period ending at 2 AM.
Still questionable flash flooding potential through the
overnight with rainfall rates so far marginal for 3 hour
guidance. However, it will need to be monitored given danger of
nighttime flooding and ingredients for heavy rain including
excellent moisture convergence and axis of maximum precipitable
water over our region on deep southerly flow. At the same time,
have cut back on thunderstorm chances through this period with
most unstable CAPE mainly under 500 J/kg, but this instability
is sufficient for heavy showers. Heaviest rain overnight looks
to set up in an axis extending northeastward from the
Adirondacks to the Northeast Kingdom, fairly well aligned with
the Flood Watch in effect after midnight.
Previous Discussion...
* FLOOD WATCH IN EFFECT FROM MIDNIGHT EDT TONIGHT THROUGH
TUESDAY EVENING *
I dare to say that guidance has finally come into better
agreement for the next 24 hours, as models have struggled over
the past few days to resolve the convective and flash flood
potential over the BTV forecast area. But, the 12Z runs,
especially the NAMnest, HREF, and HRRR really do have a good
handle on what has occurred today, and this forecast will lean
heavily on this model blend output. That said, let`s break it
down...
Current water vapor imagery and surface analysis show a complex,
dynamic, multi-low center, more fall-like system deepening over the
Great Lakes, with convection firing in the warm sector across the
central Appalachians. As the primary low tracks northeastward from
the eastern Great Lakes this afternoon through the St. Lawrence
Valley, models support the development of a meso-low over the
Poconos with origins from the aforementioned convection. With strong
low/mid level flow marked by a 40kt southeasterly 925mb jet and 50kt
south-southwesterly 850mb jet, the expectation is that the meso-low
will funnel northward through the Hudson Valley overnight and
through the Connecticut River Valley on Tuesday. For the rest of
this afternoon, the threat for a few strong storms exists for just
St. Lawrence County in New York where sunshine has broken out and
MUCAPEs are rising. This should be short-lived though as we`re
already progressing past heating. For tonight the focus will be
periods of moderate to locally heavy rain though with the atmosphere
well capped the thunder threat should be limited. Regardless, of the
lack of instability, ensemble probabilities for heavy rain >1" over
a 3-6hr period continue to increase with some areas likely seeing 1-
2" with isolated 3" overnight.
Heading into Tuesday, instability parameters still look better for
the afternoon as a strong mid-level dry slot remains progged to
shift into the region during the mid-morning to early afternoon
hours. This spells additional bad news for the flash flood threat as
significant clearing in an already juiced airmass of 1.5-2" PWATs
will aid in the development of ample surface instability to produce
strong thunderstorms heading into the afternoon hours. While
typically overdone a bit, the latest NAM3km indicates widespread
SBCAPE of 600-1200 J/kg from the Champlain Valley eastward, to as
high as 2000 J/kg. Right now our concerns are focused on all of
Vermont from Rutland/Windsor counties north, and Clinton/Essex
Counties in NY with recent flash flooding and low 1/3hr FFG of only
1-2", as any thunderstorms that develop will easily be able to
produce rainfall rates in excess of 1-2"/hr. After coordination with
WPC and our neighbors, a moderate risk for flash flooding (level
3/4) has been issued for the concerned areas, and locally we`ve
hoisted a flood watch.
Showers and storms will wane going into Tuesday night, but with
cyclonic northwest flow continuing aloft, upslope showers will
likely continue through much of the night.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
As of 1035 PM EDT Monday...Wednesday night should feature generally
dry and tranquil conditions as we get into brief upper level
ridging. Overnight lows generally in the mid 50s to low 60s, except
low 50s in the colder hollows. Patchy fog is also possible where
winds go light, given the antecedent moisture from rainfall earlier
in the week.
Shower and thunderstorm chances increase on Thursday as a southern
stream shortwave zips across the region out ahead of a northern
stream shortwave trough. At this time, it appears that storms that
form will generally be garden variety in nature due to poor mid-
level lapse rates and a lack of shear. Nonetheless, we will get more
clarity once we get into the CAM time range. The progressive nature
of the storms should also mitigate flooding or hydrologic concerns.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 1035 PM EDT Monday...Some lingering showers are possible
overnight Thursday into early Friday. But it looks like most of
Friday into Saturday will feature dry conditions as upper ridging
takes hold across the region. So the first half of the weekend
should be quite pleasant for outdoor activities. A combination of
positive PNA and negative NAO will help keep the general troughiness
in the upper level pattern, precluding any big heat at least through
mid August. Periods of showers and thunderstorms will be punctuated
by a couple of days of dry weather and pleasant conditions in
between.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...Variable flight conditions will be seen
across the BTV airspace over the next 24 hours. MVFR ceilings
have become established from the Champlain Valley and points
east, with some higher ceilings farther west where chances for
thunderstorms is greater through 06Z closer to a warm front. Any
heavier rain in scattered showers and thunderstorms through the
period will be capable of reducing vsby to IFR, but ceilings
will drive prevailing flight conditions.
Areas of LLWS will continue through tonight as a strong low
level jet of 40-50kts around mtn top levels traverses the
region. Some winds will attempt to mix to the surface, but
should only gust upwards of 20kts at terminal locations with
prevailing winds mainly SSE at 8-16kts. At MSS, NE winds should
eventually turn southwesterly around 12Z. Winds areawide will
trend westerly after 18Z as low pressure passes to our north
and east.
Outlook...
Tuesday Night: MVFR/IFR conditions possible. Chance SHRA.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Likely SHRA, Slight chance TSRA.
Thursday Night: Mainly MVFR, with areas VFR possible. Chance
SHRA, Slight chance TSRA.
Friday: MVFR/IFR conditions possible. NO SIG WX.
Friday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Saturday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.
&&
.HYDROLOGY...
As of 328 PM EDT Monday...Moderate to locally heavy rain is
expected to develop tonight, with strong thunderstorms possible
on Tuesday . Localized heavy rainfall is likely, along with the
potential for additional flash flooding, especially on Tuesday
where the Weather Prediction Center has upgraded portions of our
region to a moderate risk for excessive rainfall on Tuesday,
indicating at least a 40% chance of exceeding flash flood
guidance within a 25 miles of a point. Early prediction of
rainfall amounts are 1 to 3 inches, with the potential for
localized heavier amounts in stronger thunderstorms. The primary
impacts could be additional road and culvert washouts, along
with development of new mud/land slides across the steeper
slopes. River rises will need to be monitored closely,
especially on Tuesday into Wednesday.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Flood Watch through Tuesday evening for VTZ002>011-016>021.
NY...Flood Watch through Tuesday evening for NYZ028-031-034-035.
&&
$$
SYNOPSIS...Lahiff
NEAR TERM...Kutikoff/Lahiff
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Kutikoff
HYDROLOGY...WFO BTV
Area Forecast Discussion
National Weather Service Columbia SC
935 PM EDT Mon Aug 7 2023
.SYNOPSIS...
Moisture will continue to increase this afternoon and evening
ahead of a line of thunderstorms which will move through the
region late this afternoon and evening. There is potential for
strong to severe thunderstorms late this afternoon and evening
across the entire area. Diurnally driven convection with near
average temperatures are expected Tuesday and Wednesday with
unsettled conditions possible late in the week.
&&
.NEAR TERM /UNTIL 7 AM TUESDAY MORNING/...
Stronger convection now in the coastal plain. Although
lingering thunderstorms remain in the southeast Midlands and
CSRA, will clear all counties from the severe thunderstorm
watch as instability has weakened considerably and the air mass
has been "worked over". Deep layer shear remains strong as a
short wave approaches from the west. The short wave trough will
be coming through after Midnight, so a few lingering showers
still possible overnight. But lowered pops a bit based on radar
trends and latest HRRR model run. Adjusted temps although little
change in temperatures expected rest of the night. Cold front
should be in the Upstate toward morning. Lows in the low to mid
70s.
&&
.SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Upper trough over the eastern US will shift east of the area
with global models indicating that the surface cold front will
shift into the southern forecast area. Deepest moisture will
likely shift south of the area as HREF mean indicates a fairly
substantial moisture gradient across the area, with PWATs
lowering to around 1.4 inches north to 1.7 inches south.
Destabilization will be strongest south of the area while in our
area. However, model soundings indicate a warm nose, capping
inversion between 700-800 mb during the afternoon. With model
consensus of upper level forcing courtesy of a shortwave
remaining south of the area, severe potential has trended lower
with SPC shifted the marginal mostly south of the area. Still a
chance of showers or thunderstorms in the far southern area but
the severe threat appears to be low. High temperatures generally
near normal in the low to mid 90s, although somewhat breezy
westerly winds should allow dew points to mix out more
efficiently, keeping heat indices lower. Low temperatures in
the upper 60s to low 70s.
Model soundings show a bit more moisture in the column on
Wednesday bit of an increase in deep moisture is possible
Wednesday, although the best forcing remains to the west and to
the north through Wednesday night. Dew points likely mix out
across the northern area keeping it mostly stable with the
highest chance for thunderstorms in the CSRA Wednesday afternoon
into evening with potential for weak to moderate
destabilization. Temperatures similar to Tuesday. A shortwave
moves in Wednesday night which will keep chances for showers and
even an elevated thunderstorm overnight, especially along the
NC/SC border.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
The long term continues to show another good chance for showers
and thunderstorms for Thursday afternoon into Thursday night.
Models show a really good s/w will move from the north/cntrl
Plains and into the OH/TN Valley. At this time the threat is too
low to mention, but another round of widely scattered strong to
severe thunderstorms is possible with this system and associated
surface boundary. Long term continues to favor persistence as
it pertains to temperatures as there has been very little change
in blended guidance from run to run and while models show
subtle changes in the height fields, generally upper heights
remain consistent through the weekend with highs right around
seasonal average. NAEFS continues to indicate anomalously strong
flow with 850mb and 500mb winds near the 99th percentile. The
CSU severe probs are indicating this potential for Thursday.
Beyond Thursday, NAEFS indicates a weakening upper flow pattern
with GEFS mean showing a strengthening upper ridge over the
southern Plains. This would place us in a NW flow regime which
in addition to diurnal showers and storms would lead to the
potential for upstream convection to push into the area.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Gradual Improvement Expected as Showers and Thunderstorms Depart....
Conditions are improving at the terminals with only lingering
showers at CAE/CUB. Showers are ongoing at AGS/DNL with
thunderstorms mostly pass to the south. OGB remains in the worse
shape at this hour with thunderstorms just moving to the east.
The thunderstorm threat ends in the next hour or two for AGS/DNL
and OGB with lingering showers through the remainder of the
evening. Dry conditions and at least partial clearing is
expected later tonight. No restrictions are expected outside of
the ongoing convection. Expecting winds to shift to the west
behind the cold front Tuesday morning with gusty conditions
possible at the terminals.
EXTENDED AVIATION OUTLOOK...Restrictions possible in mainly
afternoon and evening convection Wednesday through Friday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
555 PM MDT Mon Aug 7 2023
.UPDATE...
Issued at 358 PM MDT Mon Aug 7 2023
Strong to severe thunderstorm continue this afternoon with the
possibility of hail and strong winds through early this evening.
Initial storms this afternoon across Laramie Co and the CO/WY
border produced strong winds gusting 50-60 mph along the I-80
corridor from west of Laramie to Cheyenne. Additional storms
developing over Cheyenne and Weld Co moved east but the anvil
plume began to weaken instability over the southern NE Panhandle
as noted with the latest RAP analysis limiting severe potential.
Farther west, storms have continued to develop in central WY
eastward towards the North Laramie Range closer to the passing
shortwave with most storm activity ending shortly after 8 PM MDT.
Overall, seems like the severe threat has been decreasing this
afternoon, but could still see isolated severe storms possible
with elevated instability remaining in place in Goshen/Platte
Counties north of where storm moved over earlier today. A Severe
Thunderstorm Watch continuing this evening. Additionally, latest
satellite imagery appears to show the cap breaking over the
northern NE Panhandle with a few storms developing over Box Butte
Co and farther east that will need to be monitored.
UPDATE Issued at 1203 PM MDT Mon Aug 7 2023
Latest GOES WV imagery shows a leading shortwave moving east
across western WY ahead of the large upper level trough digging
into central OR. Have seen CI this morning over northern CO and
south- central WY where slightly better upper level dynamics are
present associated with the 80-90 kt 250mb jet crossing the
central Rockies. Mainly could see gusty winds with these initial
storms along the I- 80 corridor in Carbon and Albany Co early this
afternoon as the atmosphere continues to destabilize. Numerous
WYDOT mesonet sensors have reported gusts 35-40 mph with these
initial storms.
Will continue to see increasing coverage of storms along the CO/WY
border early this afternoon before spreading east towards the NE
Panhandle. Forecast soundings show fairly dry low-levels along and
west of the Laramie Range supporting high-based storms and the
potential for strong outflow winds. Latest observations have the
dryline positioned near I-25 with KCYS recently turning out of the
NW with dew points dropping 10F degrees to 39F. However, a WYDOT
sensor along I-25 ~20 miles north of Cheyenne still sits at a dew
point of 49F degrees. CAMs continue to show numerous storms
developing over Laramie Co by 2-3 PM MDT moving east towards better
instability east of the dryline. Latest RAP continue to show 1500
J/kg in eastern WY with a well of 2000+ J/kg in the NE Panhandle
making large hail a concern today. Hodographs are also fairly
straight with mostly unidirectional shear, so expecting numerous
storm splits that could lead to a messy setup limiting discrete
cells. Will need to be mindful of any storms initially developing in
northern CO as the Bunkers left-mover motion is towards the
northeast at 30 kt.
In addition to these initial storms along the I-80 corridor, CI has
also begun along the Wind River Range closer to the upper level
shortwave passing through today. CAMs track these storms eastward
across central WY into our CWA as a second wave of storms late in
the afternoon with another threat for strong winds and hail.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 305 AM MDT Mon Aug 7 2023
Current surface analysis depicts the cold front, which dropped the
temperatures across the region, has stalled out across the southern
CONUS, as surface high pressure continues to move into the
Intermountain West from the Pacific Northwest.
Some showers and thunderstorms have continued overnight, with recent
radar imagery indicating showery activity across the I-25 corridor
and into the Nebraska Panhandle. Most of the impactful weather has
continued to subside overnight, with some gusty winds observed near
Bordeaux around 30 mph in the vicinity of shower activity. Another
active day expected for the early afternoon hours, with several
shortwave disturbances propagating within the flow. HiRes model
guidance has been consistent, with MLCAPEs hovering around 1500 to
2000 J/kg, 45 to 55 kts of 0-6 km shear, decent moisture advection
with up to an inch PWATs pushing into the Nebraska Panhandle, 700-
500mb Lapse Rates around 8.0C/km, and increasing SHIP parameters
further eastward into the Panhandle. Confidence for severe weather
is quite a bit higher for the Nebraska Panhandle, where current SPC
Convective Outlooks place Marginal and Slight Risks of Severe
Thunderstorms. However, possibilities still remain for severe
thunderstorms into western Laramie County with the RAP model
guidance placing some stronger cells across the I-25 corridor where
decent shear and lift along the shortwave disturbances will take
place. As a result, kept the chances for large hail and severe winds
in place for Laramie, Goshen, and Platte County. Main threats for
the day will include Large Hail and Damaging Winds, in addition to
fairly straight hodographs which continue to support splitting
storms and an isolated tornado risk in the right movers of the
splitting storms.
Severe weather chances continue into Tuesday, with a Marginal Risk
of severe thunderstorms for the most eastern portion of Wyoming and
a Slight Risk of Severe Thunderstorms for the Nebraska Panhandle.
Low level southeasterly flow will help maintain dewpoints in the
high-50s for the eastern most counties in the Nebraska Panhandle and
mid-50s into Goshen County. All in all, Tuesday appears to be a
repeat for what will occur later this afternoon, with thermodynamic
profiles remaining very similar for both days.
.LONG TERM...(Wednesday through Sunday)
Issued at 305 AM MDT Mon Aug 7 2023
Exiting low pressure system will give way to drier weather for
southeast Wyoming and Nebraska Panhandle Wednesday as a ridge of
high pressure builds back into the area. Cooler than normal with
highs in the 70s for much of southeast Wyoming and near 80 for the
Panhandle.
Could be breezy Thursday as a low pressure system tracks across
Montana...a favorable pattern for breezy winds. The only areas to
see any shower activity would be our western mountains. Associated
cold front looks to drop south into the CWA Thursday evening into
Friday morning with 700mb temperatures falling to 10 to 12C. Not
much in the way of precip with this front. Best chances would be
Carbon and Albany Counties where we have chance PoPs Friday
afternoon/evening.
Fairly warm for next weekend with 700mb temperatures up near +15C.
80s to low 90s pretty common across the CWA. Afternoon convection
with these warmer temperatures and instability.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 554 PM MDT Mon Aug 7 2023
Scattered showers and thunderstorms will continue this evening but
clear out by midnight. Main concerns with these storms include
strong gusty winds, hail, and heavy rain. Any storm passing over a
terminal may reduce visibility down below VFR criteria. Moisture and
calm winds overnight will lead to the development of low stratus and
potentially fog over portions of the Nebraska panhandle. KCDR, KBFF,
and KAIA could see MVFR to IFR conditions by early morning,
continuing through mid-morning.
&&
.FIRE WEATHER...
Issued at 305 AM MDT Mon Aug 7 2023
Little to no fire weather concerns for the start to the work week
with several days of wetting rains leading to fuels remaining in
green up. Could see some elevated fire weather concerns Thursday
onward for Carbon County with minimum RH in the mid-teens and wind
speeds increasing to around 25+ knots.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...MB
SHORT TERM...MRD
LONG TERM...GCC
AVIATION...SF
FIRE WEATHER...MRD
Area Forecast Discussion
National Weather Service Dodge City KS
935 PM CDT Mon Aug 7 2023
...Updated Mesoscale...
.MESOSCALE DISCUSSION...
Issued at 935 PM CDT Mon Aug 7 2023
MCS is clearly weakening as it sags southward into a much less
favorable thermodynamic environment. Instability wanes with
southern extent, but more importantly, convective inhibition is
strong (reference inversion at 700 mb on 00z DDC sounding). As
such, no more severe weather is expected east of about US 83 for
the remainder of this evening. Wind gusts to 50 mph are probable
with combined outflows, but even this will weaken with time.
Storms over western Scott and northern Kearny are still severe as
of 930 pm, closest to the greatest instability at the tail end of
the MCS. This westernmost activity will maintain potential for
severe hail and/or wind for several more hours, as it moves almost
due south.
&&
.UPDATE...
Issued at 745 PM CDT Mon Aug 7 2023
Large MCS was in progress across NW KS as of midevening. Infrared
satellite trends show cloud tops cooling with time with the
initial updrafts/supercells on the southwest flank of the
complex, with two seperate supercells producing 2-3 inch hail
across Gove county as of 740 pm. Issued an update to increase pops
further into the likely category through tonight, as strong NWly
midlevel steering flow will direct the complex into SW KS over the
next few hours. Confidence for severe hail and/or wind is highest
along and especially north of US-50, where severe wording was
included in the grids and forecast. Mesoanalysis continues to show
instability diminishing with S/SE extent, so convective severity
should decline with time across the central CWA. The notable
expection may be the western zones, where an unstable strongly
sheared atmosphere remains in place, that appears capable of
supporting severe weather from the SW flank of the MCS for the next
several hours. The risk for severe outflow and/or hail appears
highest across NW zones including Hamilton, Kearny, Scott and Lane
counties through 10 pm. Other weather elements through tonight were
on track with no other updates needed.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 137 PM CDT Mon Aug 7 2023
Midday water vapor satellite imagery and RAP upper air analysis
indicates west-northwesterly flow is present across the central
plains between a ~600dm ridge over the southern plains/northern
Mexico and weak longwave troughing spread out over the northern
CONUS. Embedded within this flow pattern are several shortwave
impulses, most notable of which are located over the Midwest and
the Pacific Northwest. The Midwest lobe will lift northeast
through the short term while the western lobe digs east-southeast
towards the central plains. At the surface, weak lee cyclogenesis
will unfold this afternoon/evening across eastern CO in response
to the approaching shortwave trough, resulting in light southeast
winds throughout our area. Associated poor WAA and 850-mb
temperatures generally in the upper teens/low 20s Celsius will
only support afternoon highs in the mid to upper 80s.
Focus then shifts to the convective threat this afternoon/evening.
Short range guidance is in agreement suggesting a weak upper
level shortwave trough, currently centered over central WY as per
water vapor satellite imagery, will dig east-southeast during the
afternoon and evening. As this feature approaches, weak surface
southeasterly flow will transport low/mid 60s dewpoints poleward
into eastern CO/western KS beneath steep mid-level lapse rates of
8-8.5 degrees C/km. This will contribute to at least 1000-2000
J/Kg of MLCAPE across western KS amidst strong deep layer shear on
the order of 45-55 kts. Current thinking is convection will
develop over the higher terrain in northeast CO, spreading east-
southeast with time and encountering this favorable environment
for severe thunderstorms that will be focused along and west of
US-83 in the DDC CWA. Hodograph shape will be supportive of
discrete supercells as the initial storm mode that will be capable
of very large hail, as well as some tornado threat centered
around the 00-04Z time range as the low-level jet enhances low-
level hodograph size/curvature. With time, upscale growth into a
severe convective complex is likely as cold pools amalgamate,
fostering a transition to damaging wind gusts as the primary
threat. That said, buoyancy drops off fairly substantially with
eastward extent, which will limit severe potential as storms
continue east through the night, so the window for severe wind
gusts may be brief. Thunderstorm activity will be mostly clear of
southwest KS by sunrise Tuesday morning, with lows ranging from
the upper 50s northwest to mid 60s southeast.
Daytime Tuesday will look very similar to Monday given little to
no change in the upper level pattern. South-southeast winds may
be slightly stronger as the lee cyclone in eastern CO deepens
further ahead of the aforementioned shortwave trough, but this
will have no noticeable impact as afternoon temperatures once
again only reach the mid/upper 80s. Thunderstorms, some
potentially severe, are again possible late Tuesday evening into
the overnight period as forcing associated with the shortwave
overspreads the area, however uncertainty exists surrounding the
impact tonight`s convection will have on the environment as well
as the late timing of the trough ejection not lining up with the
typical diurnal maximum of instability. Any thunderstorm that
does enter our area will be capable of all severe hazards given
the relatively strong kinematics in play, but confidence in a
singular convective evolution is low.
.LONG TERM...(Wednesday through Monday)
Issued at 233 PM CDT Mon Aug 7 2023
Key Messages: cold front on Wednesday will provide one final shot
of cool air before warming trend takes over through the end of the
work week. Thunderstorm potential returns over the weekend, some
potentially severe.
Thunderstorms may be ongoing at the beginning of the long term
period favoring the far eastern zones, however these should exit
quickly as the upper level shortwave trough continues eastward.
Behind this synoptic feature, a cold front will dive south through
the central plains, bringing one last shot of cool air to
southwest KS and keeping afternoon highs in the mid/upper 80s.
This front will also spell the end to widespread precipitation
chances through the end of the work week, and this is supported by
ensemble meteograms showing little to no QPF across the area until
the weekend. During this dry window Thursday and Friday,
increasing 850-mb temperatures and 1000-500-mb thicknesses will
foster a warming trend, with afternoon highs heating up from the
low/mid 90s Thursday to the mid/upper 90s Friday.
Over the weekend, medium range ensembles agree appreciable
precipitation chances will return to southwest KS, as at least 80%
of EPS/GEFS ensemble members show some degree of QPF that will
likely manifest in mesoscale convective systems emerging from CO
and sweeping across the area. Some severe potential will accompany
this activity, however mid-level flow is only progged by ensembles
to be in the 15-25 kt range, which would limit deep-layer shear to
the lower end of the spectrum. Either way, it appears our above
normal precipitation year will continue Saturday through the end
of the period, along with decreasing afternoon highs back down
into the mid/upper 80s by Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 437 PM CDT Mon Aug 7 2023
VFR will continue through this TAF cycle, outside of any
convective influence, with varied amounts of mid and high clouds.
Satellite and radar imagery at 2130z depicted severe convection
over NW KS. These storms are expected to organize into another
MCS and propogate southeast through SW KS 00-12z Tue. Using
12z ARW/18z NAM as a guide, included convective TEMPO groups for
DDC/HYS/GCK 02-07z Tue, but opted to only carry a VCTS/CB mention
at LBL. Primary impact from storms will be strong outflow winds
of 40-50 kts. Convection is expected to be exiting SW KS around
12z Tue. VFR is expected daylight Tuesday with light SE winds.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 62 85 63 85 / 70 20 40 10
GCK 60 85 62 84 / 60 20 40 10
EHA 60 89 61 87 / 30 10 10 0
LBL 61 89 63 87 / 40 10 20 0
HYS 61 87 63 85 / 60 30 60 20
P28 65 86 68 88 / 60 20 50 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Turner
UPDATE...Turner
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Turner
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
550 PM MDT Mon Aug 7 2023
...New AVIATION...
.SYNOPSIS...
Issued at 215 PM MDT Mon Aug 7 2023
After a very hot day today in parts of the area, temperatures will
cool about 5 to 10 degrees but will remain above average. Each
afternoon will feature chances for thunderstorms with the greatest
chances to see rain in the mountains.
&&
.DISCUSSION...
Issued at 215 PM MDT Mon Aug 7 2023
The UL high, which has plagued us with heat all summer, is located
to our south but is shifting to the east. This shift has allowed
moisture to increase, especially across areas west of the Rio
Grande as evidenced by the increase in cloud coverage.
Nevertheless, the high remains close enough to place El Paso in
the oven with temperatures already above 105. Thankfully, today
is expected to be the hottest day of the period.
The HRRR continues to insist showers and thunderstorms will
continue to increase in coverage later this evening and overnight.
This may be associated with a weak vort max moving from northeastern
Sonora into Southeastern AZ plus expected outflow from storms over
Central NM. Regardless, it looks like everyone has at least a low
chance of picking up a little rain tonight. Fingers crossed. These
showers may persist into the morning hours with subsequent lingering
cloud coverage. The HRRR, which has performed very well this summer,
and the RAP both indicate this possibility. The cloud coverage will
help lower temperatures along with the eastward drift of the 500 mb
high. NBM places tomorrow`s high at 105 for El Paso, which is heat
advisory territory, but current thinking is clouds will prevent us
from hitting that target. As we go into the afternoon and evening
hours, more thunderstorms are expected to develop, especially in the
mountains, but coverage will depend on how quickly clouds clear.
The H500 will continue shifting east into the Southern Plains,
which will allow the monsoonal plume to extend across NM and far
West Texas. PW values look to increase to around 1.25", which is
close to the 75th percentile for the year. It should be noted
though, the GFS is running wetter than the Euro. Regardless, the
pattern will support mountain scattered and isolated to scattered
lowland thunderstorms each afternoon. In other words, a fairly
typical monsoonal pattern. Highs will range 95-104 throughout the
period, so we should be done with heat headlines for now. Just
past day 7, the high begins expanding back west.
46 days until Autumn.
&&
.AVIATION...
(00Z TAFS)
Issued at 540 PM MDT Mon Aug 7 2023
Plenty of thunderstorms occurring this afternoon over the area.
Two outflow boundaries are racing towards KLRU, but unsure which
wind direction will win out, but expect wind speeds around
30G40KT. KTCS should generally see showery activity with a
thunderstorm or two nearby. KDMN seems to have calmed down with
showery activity dominating the area and gusty winds lingering.
KELP is the calmest terminal of them all at the moment. One of the
aforementioned outflows will be coming in from the west if it
keeps up the momentum and can flow over the Franklin Mtns, but
confidence is not high enough to mention in the TAF. Otherwise,
winds continue to remain gusty through much of the evening,
especially near thunderstorms. Models continue to keep
thunderstorm activity going through around 04-06Z, but should calm
after 06Z where VCSH may be found. All terminals have the
possibility of seeing additional storms tonight.
&&
.FIRE WEATHER...
Issued at 215 PM MDT Mon Aug 7 2023
Moisture will continue to increase across the area, especially
west of the Rio Grande. For tonight, this increase will lead to
moisture recoveries above 60 percent west of the Rio Grande and
above 50 percent east of Rio Grande. The increased moisture will
also result in an increase in showers and thunderstorms this
evening into the overnight hours. Tomorrow will not be as hot,
which along with the increase in moisture, will lead to min RH
values in the mid and upper teens. Thunderstorm coverage tomorrow
afternoon will depend on morning cloud coverage. Winds outside of
storms will top out around 10 to 15 MPH with higher gusts. We will
remain in a typical albeit hot monsoonal pattern for the remainder
of the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 82 103 79 104 / 40 10 30 10
Sierra Blanca 74 96 70 95 / 50 30 30 20
Las Cruces 77 101 73 102 / 40 10 30 20
Alamogordo 74 97 70 100 / 30 10 30 10
Cloudcroft 57 74 54 76 / 40 20 20 20
Truth or Consequences 73 96 70 97 / 50 30 20 20
Silver City 66 91 64 91 / 40 30 30 50
Deming 74 99 70 100 / 40 20 30 20
Lordsburg 71 96 68 97 / 50 40 50 50
West El Paso Metro 81 101 77 102 / 40 20 30 20
Dell City 76 101 72 102 / 40 20 10 10
Fort Hancock 78 103 74 103 / 50 20 30 20
Loma Linda 74 93 70 94 / 40 20 20 20
Fabens 79 100 75 101 / 40 10 20 10
Santa Teresa 77 99 73 100 / 50 20 30 20
White Sands HQ 79 99 74 100 / 40 20 30 20
Jornada Range 74 98 69 99 / 40 20 30 20
Hatch 73 99 69 101 / 40 20 30 30
Columbus 77 98 73 99 / 50 20 40 30
Orogrande 74 96 69 98 / 40 10 30 20
Mayhill 63 86 60 87 / 30 30 20 30
Mescalero 61 85 57 87 / 40 20 30 20
Timberon 60 83 57 85 / 40 30 20 20
Winston 61 86 58 87 / 40 50 20 50
Hillsboro 68 96 64 97 / 40 30 30 40
Spaceport 70 96 67 98 / 50 30 30 30
Lake Roberts 60 89 57 89 / 50 50 40 50
Hurley 69 95 66 96 / 40 30 20 40
Cliff 61 98 59 98 / 50 40 30 50
Mule Creek 66 92 64 92 / 40 30 30 50
Faywood 70 94 67 95 / 30 30 30 40
Animas 71 96 68 97 / 60 50 60 60
Hachita 71 96 68 97 / 50 40 40 40
Antelope Wells 71 95 67 95 / 60 50 50 60
Cloverdale 67 90 65 90 / 60 60 60 70
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until midnight MDT tonight for TXZ420>422.
Excessive Heat Warning until midnight MDT tonight for TXZ418-419-
423-424.
NM...Heat Advisory until midnight MDT tonight for NMZ401>413-417.
&&
$$
FORECASTER...37-Slusher
Area Forecast Discussion
National Weather Service Grand Forks ND
1032 PM CDT Mon Aug 7 2023
.UPDATE...
Issued at 1024 PM CDT Mon Aug 7 2023
Updated the grids and added patchy smoke for the northern forecast
area through 12z and the entire forecast area 12z through 00z.
Still seeing the high level smoke affect the area, with some of it
making it to the surface. Otherwise, shower activity has
diminished as daytime heating has been lost. Still seeing chances
for thunderstorms tomorrow afternoon and evening as a front shifts
through the region.
UPDATE Issued at 632 PM CDT Mon Aug 7 2023
Updated POPs to take into account the isolated showers and storms
in the northern forecast area. Did this through 03z. Otherwise,
added some smoke into the grids for tomorrow 12z-00z. HRRR and RAP
shows the near surface smoke increasing tomorrow through
Wednesday.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 315 PM CDT Mon Aug 7 2023
Key Points
- Mainly dry across the area tonight into early Tuesday.
- Precipitation chances increase across the area late Tuesday into
Tuesday night.
- Seasonal temperatures tonight through Tuesday night.
A northwest upper level flow pattern will remain in place through
the short term, with an upper level low spinning across northern
MB/ON for much of the period. This upper level system will slowly
wobble eastward dropping a cold front through the forecast area
Tuesday into Tuesday night. Ahead of this front, seasonal
temperatures expected with mainly dry conditions. As the front nears
the forecast area it will be situation from west to east near the
international border by mid/late day Tuesday. Some initial shower
and isolated thunderstorm development possible by mid-day near the
Canadian border. However more widespread activity possible by late
afternoon/early evening as a lobe of energy rotating around the main
low dives southeastward across the area reinforcing the front as it
drop southward across the region. Some potential for the main area
of showers/storms to be situated closer to the main upper low
further to the east/northeast, so stuck with pops in the high chance
(40-50%) for the majority of the forecast area. Did match up to
neighbors into the low likely (60%) category for the far northwest
with that secondary wave approaching the area during peak diurnal
heating. Overall instability expected to be somewhat limited with
moderate bulk layer shear which should limit overall severe
potential. However cloud cover associated with the front and earlier
shower activity could end up limiting the instability further
keeping the activity more showery in nature.
.LONG TERM...(Wednesday through Monday)
Issued at 315 PM CDT Mon Aug 7 2023
Key Messages:
- Potential for widespread precipitation Thursday into Friday with
limited severe potential.
- Slightly below normal temperatures beginning midweek and
persisting through the weekend.
The beginning of the long term period will bring northwest flow
aloft to the area as a strong upper low propagates across southern
Ontario. Several upper waves look to pass through the region
spurring sporadic precipitation chances.
Cluster analysis and ensemble output depict the best chances for
widespread precipitation to be during the Thursday to early Friday
time frame. Variability in rain amounts still exists this far out
but with the degree of synoptic forcing, at least some level of
widespread precipitation appears likely. With that said, ongoing
dry/drought conditions and lack of evapotranspiration effects may
inhibit the amount of available moisture to some degree. Limited
moisture (which is likely overdone in current model guidance) would
also point to limited instability/severe chances at this time.
Overall, NBM probabilities still depict much of the area with a 40-
60 percent chance of 0.50 inch or more and around 20-30 percent
chance of amounts greater than one inch.
No major air mass changes look to occur as the overall synoptic
pattern remains consistent with slightly below normal temperatures
expected (generally highs in the 70s and lows in the 50s).
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1024 PM CDT Mon Aug 7 2023
VFR conditions through the TAF period. High level smoke continues
to affect the region through the TAF period. Some of it may reach
the surface during the day tomorrow, with a few isolated
visibility reductions down to 6-7SM. Otherwise, shower activity
has diminished this evening. Light and VRB winds overnight will
turn toward the west tomorrow afternoon, with gusts near 20kts at
times. A front moves down from Canada, with a few showers and
storms possible along the frontal boundary as it moves SE across
the region. Should begin in DVL, GFK, and TVF first around 18-20z
and exit all sites around 04-05z. As the showers pass through the
area skies will be BKN, and winds will turn toward the north.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Spender
SHORT TERM...MJB
LONG TERM...Lee
AVIATION...Spender
Area Forecast Discussion
National Weather Service Goodland KS
602 PM MDT Mon Aug 7 2023
.UPDATE...
Issued at 413 PM MDT Mon Aug 7 2023
The Severe Thunderstorm Watch has been expanded eastward to
include Red Willow, Decatur, and Sheridan counties due to the
possibility increasing for severe thunderstorms moving farther
eastward than previously anticipated. Billowing clouds are seen on
the visible satellite product as well as buoyancy decreasing
going eastward.
&&
.SHORT TERM...(This evening through Tuesday Night)
Issued at 256 PM MDT Mon Aug 7 2023
At the start of the short term period, the latest upper air RAP
analysis shows the CWA with a west-northwesterly flow aloft with a
shallow upper air trough out to the east and an upper air low moving
just over the coast of WA. Current satellite imagery and surface
observations show dry conditions and mostly southerly surface winds
with clouds starting to bubble up/develop across a good portion of
the CWA particularly in the west. Going forward through the day,
models show an upper air shortwave disturbance developing just to
the west of the CWA around 21Z that becomes stronger and passes
over the CWA at 00Z. This disturbance looks to disappear from
influencing the CWA by 06Z while the WA low moves over southern ID
overnight. At the surface, the main story looks to be the
potential for severe weather expected for this afternoon and
evening. When looking at the current RAP analysis, there looks to
a good amount of temperature advection at the 850mb level near
the CO/KS/NE border area with a good amount of temperature
advection across most of the CWA at the 700mb level. Currently, there
also looks to be a convergence zone out in the northwestern
portion of the CWA that will allow thunderstorms to develop this
afternoon and evening. When looking at model convective
parameters, MLCAPE values along and west of CO border in the CWA
look to be at or above 2 kJ/kg particularly around 21Z-00Z while
there looks to be good 0-6km bulk shear across the CWA as well
during this time potentially reaching the triple digits in some
portions. Also, model forecast 0-3km SRH values around 200 m^2/s^2
are seen within the CWA as well. This lines up pretty well with
the SPC marginal to slight risk of severe weather for today.
Potential hazards today for storms that become severe look to be
large hail up to tennis balls in size, strong wind gusts up to 70
mph, a possible tornado or two (particularly in the northeastern
portion of the CWA), and locally heavy rainfall. Isolated
supercells look to favor more of the large hail and possible
tornado threats, but the strong wind threat will be seen as well
if they form a line this evening. The WPC currently has a marginal
risk for excessive rainfall for a good portion of the CWA which
seems to be well merited with PWAT values over 1 inch to around
1.25 inches seen in the area. There are also some scattered
pockets of 1.5 inch PWATs, so heavy rainfall with these
thunderstorms is possible and the flood threat will be monitored.
Thunderstorms look to develop in the western portions of the CWA
around 20Z-21Z and continue eastward across the CO going through
03Z-04Z. This does not look to be a potential tornado outbreak
day, but some stronger storms could be possible with a wide
variety of hazards so will continue to monitor conditions going
forward. A Severe Thunderstorm Watch which includes the potential
for tornadoes has also been issued for counties along and west of
KS-25 through 03Z. As for tonight after the storms clear the area,
lingering precipitation chances are possible for eastern portions
of the CWA with overnight lows in the middle 50s to lower 60s.
On Tuesday, models show the CWA coming underneath a weak ridge
during the day as the northwestern low moves over southern WY by
the evening hours. Another shortwave disturbance is seen passing
over the CWA during the evening as well. At the surface, models
show the possibility for some patchy fog along and north of the
KS/NE border during the morning hours. But the main story looks to
be the second day of potentially strong to severe thunderstorms
seen within the CWA during the late afternoon and evening hours.
Currently: the SPC has an enhanced risk for severe weather
centered over the northwestern portion of the CWA with most of the
remaining parts of the CWA within a slight risk. Again, potential
hazards include large hail up to a possible 2 to 3 inches in
diameter, strong winds up to 70 mph, locally heavy rainfall
leading to potential flash flooding, as well as possible tornado
or two. Latest CAM runs show storms developing in eastern CO
during 22Z-00Z that will sweep across the northern portions of the
CWA going into the night with a possible cold front moving
through the region overnight. Looking at convective parameters,
model MLCAPE values over 2000 J/kg are seen across the CWA along
with 0-6km bulk shear values around 50 kts. As for the potential
for heavy rainfall, similar PWAT values of 1-1.25 inches are seen
across the CWA though there looks to be a good swath of 1.5 inches
along the KS/NE border which supports the WPC excessive rainfall
slight risk for a good portion of the CWA. Will continue to watch
this storm potential and provide forecast updates as they become
available. Daytime highs for Tuesday expect to be in the lower to
middle 80s with overnight lows in the lower 50s to lower 60s.
.LONG TERM...(Wednesday through Monday)
Issued at 357 PM MDT Mon Aug 7 2023
At the start of the long term period, models show a weak upper air
trough passing over the CWA on Wednesday morning with the GFS
being slightly quicker than the ECMWF in the progression. By
Wednesday evening, the front part of a trailing ridge looks to
move over the CWA. Going into Thursday, models project the CWA
being underneath the ridge through the early afternoon hours
before the upper air flow starts to turn more westerly being in
the peak of a upper ridge over the south-central CONUS during the
evening hours. Models continue to have CWA underneath the peak of
the upper air ridge on Friday while showing an upper air low
moving off the coast of central CA. An upper air shortwave is seen
passing over the CWA during the Friday evening hours as well.
Going through the weekend and Monday, long term forecast guidance
starts to depart from their solutions a bit though continue to
have an upper air high over the TX with the upper air low
meandering around the CA coast. The GFS hints at more evening
shortwave disturbances passing over the CWA at least during the
weekend as well.
At the surface, the forecast calls for dry conditions on Wednesday
and most of Thursday with slight chances for precipitation seen
Thursday night as well as in the latter half of Friday. The best
chances for precipitation currently look to be on the weekend and
also Monday associated with the potential upper air shortwave
disturbances. Will continue to monitor this going forward as
details become more clear in future model runs. Temperatures look
to cool on Wednesday following a cold front passage before
rebounding beginning on Thursday going through the weekend.
Daytime highs on Wednesday range between the upper 70s and middle
80s while Thursday through Saturday with highs a few degrees on
either side of the 90 degree mark. Sunday`s daytime highs are
forecasted to be in the middle 80s to lower 90s followed by highs
in the middle to upper 80s on Monday. Overnight lows on Wednesday
night look to be in the middle 50s to lower 60s while lows in the
upper 50s to middle 60s are seen on Thursday through Saturday
nights. Sunday and Monday nights have overnight lows ranging
between the upper 50s and lower 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 545 PM MDT Mon Aug 7 2023
Adverse aviation conditions associated with thunderstorms are
anticipated at both terminals at the beginning of the TAF period,
mainly in the 00-03Z time frame. A period of fog cannot be ruled
out at either terminal AOA sunrise Tue morning, with the relative
best chance at the MCK terminal. Otherwise, VFR conditions and
light/variable winds are anticipated to predominate through the
TAF period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...076
SHORT TERM...076
LONG TERM...076
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Green Bay WI
1028 PM CDT Mon Aug 7 2023
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 247 PM CDT Mon Aug 7 2023
Synopsis: Low pressure will continue to exit the region over the
eastern Great Lakes through tonight, while a decaying cold front
will sag into northern Wisconsin late this afternoon into tonight.
On Tuesday, weak high pressure will settle across the region as a
weak shortwave (currently over the northern Plains) moves across
southern Wisconsin and northern Illinois.
Sky & Precip: Convective clouds will continue to build over
north-central WI within a weak moisture axis ahead of the decaying
cold front. A few showers have developed over the hour and convective
allowing models continue to generate isolated showers and storms
within this moisture axis into the evening. Both the HRRR and RAP
are under doing surface based instability (currently estimated at over
1000 j/kg). With temps approaching their convective temps early
this afternoon, isolated to scattered showers/storms remain
expected to develop and slowly move southeast before dissipating
prior to reaching the Bayshore and the Fox Valley late this
evening. Thereafter, clearing skies and light winds will promote
ground fog formation, particularly where showers occur.
Tuesday will generally be a quiet and seasonable late summer day
with temps a few degrees above normal. A few convective allowing
models generate light showers in a convergent area of far
northeast WI late in the afternoon. However, forecast soundings
show a significant cap between 10 kft and 15 kft, which will be
hard for any convection to overcome considering the high cloud
heights. Therefore removed precip chances.
Temps & Winds: Used the best performing guidance for temps over
the next 24 hours as the airmass changes little. Temps should
therefore remain slightly above normal. Light north winds today
will back to the northwest on Tuesday.
.LONG TERM...Tuesday Night Through Monday
Issued at 247 PM CDT Mon Aug 7 2023
An elongated upper-level high pressure to extend from FL to TX
into the northwest CONUS by this weekend. A low amplitude flow
across the northern tier of states will bring a series of
shortwave troughs and cold fronts through the Great Lakes region
with an assortment of precipitation chances. Timing of each system
remains a challenge as models differ, thus making for a low
confidence forecast.
Tuesday night and Wednesday...
Quiet conditions are expected Tuesday night with a very weak area
of high pressure drifting through the area. Mostly clear skies
will prevail for most of the night, although some high clouds may
start to arrive toward daybreak over north-central WI from a
system moving into the Upper MS Valley. A light west-southwest
wind will begin to tap warmer air with min temperatures to range
from the middle 50s north-central WI, to the lower 60s east-
central WI. Models continue to advertise two separate shortwave
troughs moving east across the e-central CONUS. One trough is
forecast to move from the central Plains into the mid-MS Valley,
while the second trough moves from the Canadian Prairie into
southern Ontario/northern Great Lakes. Strong mid-level forcing to
stay north or south of northeast WI, however a cold front will be
sagging south through the forecast area through the day. Despite
peak heating, instability is marginal at best with SBCAPES < 200
J/KG. There is pretty strong shear present (35-45 knots), thus any
storms that can develop may become locally strong with gusty
winds. Have kept pops in the chance category for now with higher
values across the north where stronger shear to be present. Max
temperatures to be in the upper 70s to around 80 degrees north,
middle to upper 80s south.
Wednesday night and Thursday...
Chance pops will need to be carried over through at least
Wednesday evening as the cold front and both shortwave troughs to
still be in the process of exiting the area. Skies should then
begin to clear from northwest to southeast with a push of CAA
behind the front. Min temperatures Wednesday night to be in the
lower to middle 50s (a few upper 40s possible in our typically
colder spots), middle 50s to around 60 degrees south. Northeast WI
to reside between systems on Thursday and with little evidence of
any forcing mechanisms, have kept the day dry under partly cloudy
skies. Max temperatures to be a bit cooler behind the cold front
with readings in the middle to upper 70s north/near Lake MI, lower
to middle 80s south.
Thursday night and Friday...
Clouds will be on the increase Thursday night as the next cold
front/shortwave trough move southeast from the Canadian Prairie
into ND/Upper MS Valley. A push of WAA ahead of this system could
already bring a chance of showers/thunderstorms into northeast WI
after midnight. This system will move into the Great Lakes on
Friday with sufficient lift/forcing/moisture present to bring a
good likelihood of showers/thunderstorms to the forecast area.
Severe potential looks limited based on the current timing of rain
late Thursday night into Friday. If this system were to slow
down, then we would need to re-evaluate the situation. Max
temperatures on Friday to be in the upper 60s to lower 70s north,
middle 70s to around 80 degrees south.
Friday night and Saturday...
Precipitation chances could linger through most of Friday night
depending on the exact timing of the system. Anticipate mainly
just showers by this time as better lift/instability to have
shifted east. There is a concern for small precipitation chances
returning to northern WI on Saturday as a cyclonic flow and weak
shortwave to be in the vicinity. Any precipitation appears to be
on the light side. Otherwise, generally partly sunny skies are
expected on Saturday with max temperatures in the upper 60s to
lower 70s north, middle to upper 70s south.
Saturday night through Monday...
Forecast confidence is rather low by the start of next week as
model timing of subsequent systems diverge quite a bit. Some
models bring precipitation chances on Sunday, others say Monday.
Due to this large spread in timing, have deferred to the consensus
solution which brings small chance pops to the forecast area for
both Sunday and Monday. Temperatures would be close to seasonal
normals.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1023 PM CDT Mon Aug 7 2023
An isolated shower is still possible across northern Wisconsin
through 06z, otherwise patchy fog will be the main concern.
The greatest potential for for will be across northern Wisconsin
where CIGS/VSBY`s may fall into the MVFR/IFR or lower category.
Any fog should burn off by 14z Tuesday. Fair weather cumulus will
develop late tomorrow morning and continue into early Tuesday
evening between four and six thousand feet. For the KMTW TAF site,
have the northwest winds veering southeast by 21z with lake
breeze. Northwest winds are expected to gust to 15 knots into
mid afternoon before becoming light and variable around sunset.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kallas
AVIATION.......Eckberg
Area Forecast Discussion
National Weather Service North Platte NE
641 PM CDT Mon Aug 7 2023
...Aviation discussion...
.SYNOPSIS...
Issued at 332 PM CDT Mon Aug 7 2023
Key Messages:
-Strong and severe storms are forecast for portions of SW and North
Central Nebraska both this afternoon/evening and tomorrow
afternoon/evening.
-The atmosphere favors the formation of severe hail /some of which
may be greater than 2"/ across Western/SW Nebraska this afternoon.
-There is an enhancement of low level winds that would promote
supercells capable of all severe weather modes across far
southwestern Nebraska this afternoon, including a low /5%/ tornado
risk.
-Tuesday afternoon, the latest machine learning probability
forecasts indicate a more widespread threat of all severe weather
modes for western and north central Nebraska.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 332 PM CDT Mon Aug 7 2023
12z analysis of the mid and upper levels reveal west northwesterly
flow that prevails across the High Plains with a fairly strong mid-
level jet nosing into the region. At the surface, dew points have
remained in the upper 50s to lower 60s, but have been pooling as of
late along the South Platte River Valley in southwest Nebraska and
far northeast Colorado. Skies have remained mostly cloudy in a warm-
air advection regime with on and off showers and embedded
thunderstorms today, though where clearing has occurred, Cumulus has
sprouted. Initially the clouds have struggled and been broadly
developed, though over the past hour there`s been increasing
evidence of glaciation in the updrafts as support arrives from an
upstream disturbance. The greatest agitation in the CU field has
been along a presumed surface trough that extends from northeast
Colorado into far western Cherry County and along a lifting front
that has been loosely analyzed across far southwest Nebraska.
The CAMs have consistently suggested two main areas of convection
this afternoon. The first is a lone supercell that drops southeast
from northwest Nebraska across much of the Sandhills. RAP
hodographs are elongated in this case with increasing instability.
Large hail and wind are the primary concerns if storms do develop
across our northwest.
More concerning is the potential of severe convection developing off
the High Plains and Eastern Colorado and the Laramie Range and move
into SW Nebraska. The latest analysis suggest more than sufficient
SR wind fields that increase into the evening hours. Supercells with
large hail /greater than 2"/ are a possibility in this regime.
Additionally, brief tornadoes are not out of the question along the
boundary. Based off the forward motion generated by the CAMs, the
storms should be moving at a good clip, so heavy rainfall would only
be brief and a transient concern. There will be some upgrowth to a
complex later this afternoon/evening, which would impact southwest
Nebraska with higher wind threat. ML probabilities are highest
across southwest Nebraska this afternoon and evening, with hail
dominating the threats, though there are indications of a wind
maximum /which is also shown in the CAMs/ across portions of Chase
and Hayes Counties with a 2% tornado risk generally south of I80.
More of the same is forecast Tuesday afternoon and evening, though
ML probabilities have a greater coverage across the forecast area.
This is due to increasing moisture shown in all available guidance.
Once again elongated hodographs and ample instability will promote
supercells with large hail. Tornadic threat will be greatest along
any boundary and early in the evolution as the development of a low
level jet later will help force a convective system. CSU-ML
probabilities have hail as the greatest threat, though I would
expect wind probabilities to increase as the CAMs are fixed on
developing a linear system.
.LONG TERM...(Wednesday through Monday)
Issued at 332 PM CDT Mon Aug 7 2023
The ensembles display good agreement in that a wave dropping into
Kansas overnight Tuesday and early Wednesday. Transient short-term
subsidence will take hold and allow for mainly dry conditions. The
ECMWF ensemble EFI output and machine learning are both muted for
the CWA after the wave moves through Thursday until the next wave
moves in Thursday evening. There appears to be some moisture in
place with the cap breaking late in the afternoon or evening. At
this point the ensembles favor north central Nebraska and points
north, though confidence is low.
The next shot of precipitation comes in during the Saturday
afternoon/evening timeframe with ML probs already highlighting at
least a 15% chance of severe storms.
Overall confidence is low on severe storms in the long term, but
confidence is moderate with the overall pattern which leads to
moderate confidence in periodic unsettled conditions. Probabilistic
output favors below normal to near normal temperatures through the
long term period with better than average confidence of a slight
cool down late week/next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 641 PM CDT Mon Aug 7 2023
A cluster of supercells moving across the sandhills may impact
KLBF between 03Z-05Z with potential heavy rainfall, strong gusty
winds, and hail. Have structured the TAFs for most likely timing
but will amend as needed based on radar trends. Storms upstream
of KVTN are not expected to reach the vicinity of the airfield so
will maintain a dry forecast here. There is a good signal for a
bloom of fog/stratus toward daybreak and will indicate a period of
MVFR/IFR for a few hours past daybreak Tuesday. Expect a return
to VFR across the region by mid Tuesday morning with additional
thunderstorms expected to hold off until after this valid period.
Strong erratic wind gusts can be expected in the vicinity of any
thunderstorms. Outside of thunderstorms, winds will generally be
light at or below 10kt.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Jacobs
SHORT TERM...Jacobs
LONG TERM...Jacobs
AVIATION...MBS
Area Forecast Discussion
National Weather Service Pendleton OR
709 PM PDT Mon Aug 7 2023
.UPDATE...Latest water vapor imagery shows the upper low that was
responsible for the widespread shower and thunderstorm activity
today beginning to shift to the east of the region. All of the
colder cloud tops are now east of the forecast area and have
updated the forecast for less than 15% pops after 8 pm this
evening. Made some other mostly minor adjustments to the cloud
cover and wind grids for this forecast package. Tuesday looks like
a nice day with seasonably warm temperatures and light winds
(except for a bit of a breeze in the Cascade gaps). There will be
some high clouds around but otherwise no major weather concerns
expected. 78
&&
.PREV DISCUSSION... /issued 431 PM PDT Mon Aug 7 2023/
SHORT TERM...Tonight through Wednesday night...The main concerns
in the early short term period will be showers and isolated to
scattered thunderstorms this evening. There is a 60-80% chance of
wetting rains from showers and thunderstorms. And some storms may
produce heavy downpours, which may cause flash flooding, mainly
over recent burn scars (10-30% chance). A closed 500 mb low
pressure area is circulating abundant moisture around it over the
CWA. Heavy rain has been reported at KMEH and KALW and a few other
locations. As of 19Z, KMEH received 0.38 inch of rain since 15Z
this morning. The convection has not been strong, and
thunderstorms have so far been weak. However, the extensive
coverage of rain, some from thunderstorms, has been vastly over
northeast OR and southeast WA. There is still a moderate chance
(40-60%) of flash flooding over burn scars from heavy rain from
thunderstorms in the Wallowa County area. Will therefore leave the
Flash Flood Watch there in effect. There is more time for more
intense thunderstorms to develop during afternoon heating, before
dark, especially if there is any clearing that takes place. Both
the HRRR and NAM Nest ensembles are still showing Wallowa County
to be one of the areas with the greatest thunderstorm potential
this afternoon and evening. Another area is Grant County, in the
Strawberry and southern Blue Mountains. SPC has extended the area
of both MRGL and SLGT chance of excessive rainfall over northeast
OR and southeast WA, especially over Wallowa County.
Further west and south, there has been some clearing that took
place. In the areas, where there has been some clearing,
temperatures have risen into the 80s, while most locations under
the rain shield have had temperatures staying mostly in the 60s to
mid 70s so far today. RHs and dew points have been high area-
wide, resulting in little concern for critical fire conditions.
The upper low over the CWA will slowly move out this evening to
the southeast and it will be replaced by a shortwave ridge. This
will bring drier conditions to the forecast area late tonight and
on Tuesday. High temperatures on Tuesday will be much warmer than
today, with highs in the lower elevations and in central OR in the
80s to lower 90s, and mostly mid 70s to mid 80s in the mountains.
Minimum RHs will be significantly lower, with readings in the mid
teens to mid 20s percent in central and north central OR, and
mostly 20 to 30 percent elsewhere (high forecast confidence
80-90%).
On Wednesday, a shortwave trough will move across the Pacific
Northwest. There will be some weak instability (MUCAPE up to 300
J/kg, and LIs from -1 to -2) over the far eastern and northeast
mountains, mainly from eastern Grant County northeast to Wallowa
County. There will be a low chance (15-20%) chance of isolated
thunderstorms during the afternoon in these areas on Wednesday.
High temperatures on Wednesday will be several degrees cooler than
Tuesday due to increased cloud cover and showers.
Also on Tuesday, it will become breezy to windy, mainly along the
Cascade east slopes, the Cascade gaps, and the valleys just to
the east of the Cascades. This includes the eastern Columbia River
Gorge into the western Lower Columbia Basin of OR, the Kittitas
Valley and in central OR.
A drier and more zonal flow pattern will develop Wednesday night
going into the extended forecast period, with an eventual warming
trend expected. 88
LONG TERM...Thursday through Monday...Outside of a few
disagreements, ensemble guidance generally depicts a dry period for
the long term with the synoptic pattern wavering between that of
zonal flow and ridging with an axis centered just off the Pacific
coast. End result should be clear skies with gradually warming
conditions, but with most of the guidance that depicts ridging
keeping the axis offshore, any upward trend in temperatures would be
more gradual with values only a tad bit above average. As of now,
models are not suggesting a robust heat wave, but temps do look to
climb towards the upper 90s in the lower Basin by the end of the
period. Confidence in this outcome is moderate (40-50%) as it is a
week out, with just a slight repositioning of the ridge needed to
lead to a meaningful change in the temperature forecast.
The only potential source of sensible weather would be from a
glancing blow from a cutoff low lifting to the northeast from SoCal
over the weekend, a feature that is seen across both the
deterministic GFS and ECMWF but is only barely seen across ensemble
clustering. Models largely agree on carrying this system away from
our area of influence, but a slightly more westward track could lead
to some elevated convection across central OR and the eastern
mountains. But with the majority of guidance leaning towards a dry
forecast, will advertise quiet conditions through early next week
for now. Evans/74
AVIATION...00z TAFs...VFR conditions will prevail through the
period. Decreasing cloud cover expected though there will be some
high cloudiness through Tuesday. Winds will be terrain driven mostly
10 kt or less. 78
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 57 87 59 84 / 10 0 10 10
ALW 61 90 64 88 / 10 0 10 10
PSC 63 90 66 90 / 0 0 10 10
YKM 57 89 62 86 / 10 0 10 10
HRI 61 91 65 89 / 10 0 10 10
ELN 60 86 62 82 / 0 0 10 10
RDM 49 88 52 84 / 0 0 0 0
LGD 53 87 56 84 / 10 0 10 10
GCD 51 87 54 86 / 0 0 0 10
DLS 61 90 65 85 / 0 0 10 10
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
SHORT TERM...78
LONG TERM....74
AVIATION...78