Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/25/18
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Tue Jul 24 2018
.UPDATE...
Issued at 925 PM CDT Tue Jul 24 2018
Monitoring the evolution of two alto-cumulus fields which
continue to show deeper elevated convection per radar trends
through 0240 UTC. The broader field was located from along US-
Highway 2 through Lake Sakakawea, with a second field from near
Beach through Dickinson. Do expect convection to continue to
slowly intensify over the next 2 to 3 hours with increasing
forcing. The 00 UTC Hi-Res ARW/NMM and NAM NEST are in, as well as
the HRRR through the 01 UTC iteration, and continue to signal the
potential for a line of organized convection. This is most
notable within the rather high updraft helicity tracks. Based on
observed and CAM trends, confidence has increased somewhat to
enhance expected threats to damaging winds to near 70 mph and
large hail to half dollar size.
UPDATE Issued at 702 PM CDT Tue Jul 24 2018
Severe convective potential overnight, beginning around the 05-06 UTC
timeframe, highlights the near term forecast.
The operational and the ESRL experimental HRRR through their 21-23
UTC iterations consistently depict a line of elevated convection
potentially developing around the 05-06 UTC timeframe around
North Dakota Highway 200. This general depiction is also seen in
the 18 UTC NAM NEST, and the 12 UTC Hi-Res Window ARW and NMM runs
from 12 UTC. This initiation would be in response to
strengthening low level warm air advection with a low level jet
with convergence along a stalling warm front. Additional forcing
would be added by the mid level jet, which would also lead to
strong effective deep layer shear around 45-50kts. Overall,
elevated instability is modest, around 600-1200 j/kg. A high
shear/modest CAPE parameter space with shear vectors with a large
component parallel to the elevated boundary would support the
potential for a quick upscale growth into a few organized line
segments that would propagate southeast through the overnight.
Regarding threats, despite the strong deep layer shear, rather
low moisture levels may limit the hail threat to not much more
than a marginal severe threat. Damaging wind is a bit more
uncertain, and could conditionally pose a higher risk. Storms that
form would be high based above a deep low level dry layer that
would be favorable for damaging winds to the surface, especially
with any bowing segments. What adds uncertainty though is the
stabilization of the boundary layer quickly after sunset with the
dry air, and how that will impact momentum transfer to the
surface. Again, the damaging wind threat is higher than the hail
threat, although somewhat conditional. This has been coordinated
with SPC as input into their upcoming Day 1 update.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 316 PM CDT Tue Jul 24 2018
The main forecast concern for the short term is the potential for
strong to severe thunderstorms this evening and tonight.
Scattered showers and isolated thunderstorms have developed along an
area of weak low-level convergence across northwest North Dakota
this afternoon. This activity is not expected to become severe, as
it is moving over a fairly stable air mass. A lack of strong forcing
mechanisms and a subtle cap will likely prevent convective
initiation over a modestly unstable airmass across central and
southern North Dakota through the afternoon.
Later this evening, low to mid-level frontogenesis will increase in
response to a shortwave trough moving down from Saskatchewan.
Convection is forecast to develop along the strengthening boundary
later this evening, and may hold off until closer to midnight as
recent runs of the HRRR have been suggesting. MUCAPE will be limited
to 500-1500 J/kg, but bulk effective shear exceeding 50 kts will be
sufficient for strong to severe storms. Shear vectors oriented
parallel to the boundary should promote quick, upscale growth into
multicell linear clusters. This, combined with a relatively dry
moisture profile, means damaging wind gusts will be the primary
threat, though marginally severe hail cannot be ruled out. Despite
the overall lack of atmospheric moisture, will need to watch for
training storms along the boundary.
Thunderstorms will move off to the south and east Wednesday morning
as the upper-level shortwave moves through the state. Cyclonic flow
aloft combined with steep low-level lapse rates may produce isolated
showers and storms Wednesday afternoon, though moisture will be
limited. This potential is not high enough to include a slight
chance PoP at this time. Look for breezy conditions Wednesday
afternoon, with north-northwesterly winds around 15-25 mph, possibly
gusting to 35 mph across the north.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 316 PM CDT Tue Jul 24 2018
Cool and dry Canadian high pressure will then build into the
Northern Plains Wednesday night through Friday. Under this air mass,
expect temperatures 5 to 15 degrees below normal, with highs in the
70s and lows in the upper 40s to mid 50s.
A return to a more active pattern is suggested by model guidance for
the weekend into early next week. The general synoptic pattern calls
for an upper-level high over the Desert Southwest and longwave
troughing across the Great Lakes region. In between the ridge and
trough, various disturbances are forecast to move across the
Northern Plains. The influence of height rises from the upper-level
high should return temperatures to near normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 925 PM CDT Tue Jul 24 2018
A line of thunderstorms developing as of 0240 UTC south of
KISN/KMOT will continue to intensify and increase in coverage as
they move southeast through the overnight. The greatest impacts
are expected to KBIS/KJMS. Damaging winds and large hail are
possible. See TAFs for expected timing and impacts.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PA
SHORT TERM...Hollan
LONG TERM...Hollan
AVIATION...PA
Area Forecast Discussion
National Weather Service Cheyenne WY
629 PM MDT Tue Jul 24 2018
.UPDATE...
Issued at 626 PM MDT Tue Jul 24 2018
Isolated thunderstorms and shower activity ongoing near the
Wyoming/Nebraska border this evening. Increased POP across the
southern Nebraska panhandle since the activity has been a bit more
pronounced just west of this area. Expected thunderstorms to
continue over the next few hours before ending prior to 10 PM.
Stronger thunderstorms may linger across the far northern NE
panhandle past midnight tonight.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM MDT Tue Jul 24 2018
Currently...Surface front analyzed over southern Montana this
afternoon. Has not shown much southerly movement over the past 6
hours. Surface high pressure over central Colorado. Latest radar
imagery showing some light cells developing over the Laramie
Range, just south of Douglas drifting southeasterly and dying once
they come off the Laramie Range. SPC mesoanalysis surface based
CAPES ranging from 2500 J/KG down here near Cheyenne to 4000 J/KG
across northern Niobrara County. Shear almost non existent over
southeast Wyoming with 45-50kts from Lusk into most of the
Panhandle.
Using the latest HRRR guidance as the main tool on this afternoons
forecast. Shows a few cells developing over the Laramie Range and
drifting off to the east southeast after 22Z. Guidance shows these
storms intensifying as they get into the better CAPE and shear
across extreme southeastern Wyoming and into the Panhandle. Pretty
strong to severe cell forecast just north of Cheyenne at 23Z that
bows out over Kimball County around 01Z. So kept severe wording
in the forecast for this afternoon and early evening.
Front continues to drift south into the CWFA this evening into
tomorrow. By 09Z tonight, front forecast to be over Lusk and
Douglas. By 18Z, this front is forecast to be laying along the
east slopes of the Laramie Range. Do think the Thunderbirds
flight in the morning will be ok as low level winds will still be
out of the northwest before turning northeast during the
afternoon.
By afternoon though, low level winds shift northeast and am
expecting an increase in low level cloudiness. All PoP guidance
showing widespread precipitation developing late afternoon into
the evening hours. Afternoon CAPE expected near 1800 to 2000 J/KG
tomorrow afternoon with PWATs of 1 to 1.25 inches. Heavy rain
looking likely for the Cheyenne area during the afternoon and
evening hours and have increased PoPs to around 80 percent.
Fortunately, storm motions are still fairly fast from northwest to
southeast at 20-25kts. If storm motions come in slower, we will be
dealing with Flash Flood concerns. Later shifts may want to
consider a Flash Flood Watch for Wednesday afternoon and evening.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 230 PM MDT Tue Jul 24 2018
A rather wet forecast expected through Sunday as that stalled out
front interacts with the monsoonal moisture. Have maintained high
PoPs each afternoon/evening through Sunday. Will be dealing with
heavy rain potential and potential for flash flooding for areas
east of the Laramie Range each day.
Finally see a drying out after Sunday night as Four Corners high
builds northwest into northern Nevada and northern Utah.
&&
.AVIATION...(For the 00Z TAFS through Wednesday afternoon)
Thunderstorms will continue over far eastern Wyoming and western
Nebraska through 05z late this evening. Kept VCTS over the western
NE terminals, but generally expect VFR conditions to prevail with
gusty outflow winds from thunderstorms. Will also keep an eye on
possible fog development tonight where significant rain does fall in
addition to a cool front moving southward across the eastern plains.
As of right now, confidence is too low on where/when any fog will
form.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Tue Jul 24 2018
Minimal fire weather concerns through Sunday as monsoonal moisture
remains over the area. Looking at above critical afternoon
humidity with good to excellent humidity recoveries overnight.
Also looking at fairly widespread wetting rains beginning
Wednesday as a slow moving cold front moves into the area from the
north and stalls along the Laramie Range. This front and the
mountains will serve as a focusing mechanism for showers and
thunderstorms. Bigger hazard will be flash flooding on the Badger
Creek burn scar that we will need to watch closely.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...TJT
SHORT TERM...GCC
LONG TERM...GCC
AVIATION...TJT
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Grand Forks ND
1006 PM CDT Tue Jul 24 2018
.UPDATE...
Issued at 1005 PM CDT Tue Jul 24 2018
Additional adjustments made to near term PoP/Wx to account for
current trends with activity developing across north central ND.
This is generally matching HRRR (though a touch early and more
extensive to the north than HRRR originally had). Expecting
cluster of storms to increase in coverage and transition
southeast into our western CWA late this evening and continue
thorugh the early morning Wed (matching previous trends). Severe
threat still appears to be possible with strong shear and elevated
CAPE 1500-3000 J/KG. I`m keeping messaging at 60 mph/1" hail for
now for stronger activity late tonight, though I could see a
potential for stronger wind if stable low levels are too much of a
hindrance.
UPDATE Issued at 558 PM CDT Tue Jul 24 2018
Adjusted near term PoPs/Sky to match radar/satellite trends
showing isolated to scattered showers over our northwest CWA ahead
of weak mid level impulse. Most activity is probably just
sprinkles, but there are a few pockets of 40dbz. There may be
enough instabiility for a few weak thunderstorms as well, but so
far trends seem to favor showers early on.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 248 PM CDT Tue Jul 24 2018
Afternoon satellite imagery shows an upper level low positioned
across south central Canada with a secondary lobe of vorticity
just to its west. With the passage of the main upper level trough
over the region this morning and day time heating allowing for low
level adiabatic lapse rates, strong mid level winds have been
mixing down to the surface and allowing for wind gusts up to the
20 to 25 knot range across far northeast ND and northwest MN.
These winds will continue through sun down before gradually
diminishing.
The secondary lobe of vorticity is expected to push southeastward
into the north central CONUS overnight tonight. Ahead of this,
differential vorticity advection will allow for a few showers and
thunderstorms across central ND. Most CAMs suggest low to moderate
elevated instability will be in place across the region overnight
tonight, and coupled with strong bulk wind shear, will allow for
thunderstorm chances, a few of which may be strong to severe,
though widespread severe coverage is not expected. Storms may also
be focused along a weak surface boundary draped east to west just
north of the I-94 corridor later this evening, though surface
forcing will likely be weak.
Showers and storms that do develop will propagate southeastward
into the southern Red River Valley by Wednesday morning. Strong
mid level cold air advection on the back side of the surface low
associated with the vort lobe/upper level low may allow for some
shallow instability tomorrow afternoon (granted cloud cover does
not prevent adequate daytime heating). This instability may be
realized in the form of shallow convective showers scattered
across the region. However, confidence in this scenario is low at
this time.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 248 PM CDT Tue Jul 24 2018
The FA remains in northwest flow at 500mb for Wednesday into
Thursday, as the 500mb low tracks through southern Ontario. Some
lingering showers are possible Wednesday night, but mainly over
northwest Minnesota. A cold pool aloft may lead to some instability
showers on Thursday, and again mainly over northwest Minnesota.
Highs Thursday remain cool, then begin a slight warming trend by
Friday.
Highs look to get back closer to normal for the Saturday through
Tuesday time frame. There is some short wave energy over the FA for
the weekend, so there could be some scattered showers and storms
around. At this point, it looks pretty minimal, but will have to
keep an eye on it. Ridging pushes back in by Monday and Tuesday,
which would favor a dry period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 635 PM CDT Tue Jul 24 2018
VFR conditions should prevail, with main concern focused on
possible shower/thunderstorms development across ND which could
move into NW MN. Currently best chance will be across southeast ND
with impacts expected at KFAR. There is less confidence further
north and east, but VCTS still appeared warranted at KDVL and
KGFK based on current model trends. Wed morning MVFR stratus may
develop into NW MN, but this appears to remain north of KTVF/KBJI,
but will need to be monitored. Winds should become light and
variable increasing from the northwest late in the TAF period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...DJR
SHORT TERM...AM
LONG TERM...Godon
AVIATION...DJR
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1050 PM EDT Tue Jul 24 2018
.UPDATE...
Issued at 1050 PM EDT TUE JUL 24 2018
Did a quick update to drop the thunder from the grids, zones,
and HWO. Also added in the latest T/Td obs and trends. The updated
grids have been sent to the NDFD and web servers.
UPDATE Issued at 730 PM EDT TUE JUL 24 2018
23z sfc analysis shows a broad area of low pressure over eastern
Kentucky beneath a filling and slowly departing upper level low.
This has sprung up convection mainly just east of the JKL CWA with
a few pin prick showers showing up across the CWA leaving little
more than a trace of rain behind. The CAMs and HRRR suggest that
the far eastern part of the area still may see some showers and
thunderstorms through the rest of the evening. Will continue this
idea in the grids. Have also beefed up the fog in a hybrid
situation of stratus build down in the east and radiational
cooling in the west could result in patchy dense fog for a time in
the valleys west and mainly on the ridges east. Will update the
HWO to add that concern in for the overnight and also run a new
set of zones to not limit the fog to the valleys. An SPS may be
needed later this evening or early overnight - similar to last
night. Currently under partly to mostly cloudy skies temperatures
generally in the mid to upper 70s while dewpoints run in the mid
60s to lower 70s across eastern Kentucky. Winds remain mainly
light from the north. Did also add in the latest obs and trends
for the T/Td grids with this updated. The freshened grids have
been sent to the NDFD and web servers. Look for an updated set of
zones and HWO to follow shortly.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 346 PM EDT TUE JUL 24 2018
Showers have been sparse thus far as extensive low stratus has put a
damper on instability across eastern Kentucky. Local lift has also
been somewhat dampened as an upper low spins across the southern
Appalachians, placing the brunt of its associated lift east of the
Commonwealth. Water vapor continues to show a tight mid-upper
level moisture gradient across central into portions of eastern
Kentucky, with drier air attempting to nose eastward on the
backside of the upper circulation. Light northwest surface winds
and the nearby presence of cyclonic flow are enough to warrant
isolated to scattered showers across the higher terrain of eastern
and southeastern Kentucky with the lack of lift and drier air,
evidenced by dewpoints in the low-mid 60s, winning out across
much of the Bluegrass and Lake Cumberland regions. Have confined
thunder to a slight chance mention given the dampened instability
and more cellular convection embedded in the greater/deeper
moisture and more appreciable forcing across the Virginias and
Carolinas.
What precipitation can develop will diminish this evening with
sunset, leading to mostly cloudy conditions overnight. Stratus build-
down will impact local ridges, while areas of river valley fog
materialize underneath any breaks in the clouds. This again will be
more prevalent east of the Bluegrass region and Interstate 75
corridor where enhanced moisture resides. Fog will mix out as cloud
ceilings gradually lift by mid Wednesday morning ahead of an
approaching cool front. This front will help to spark afternoon
convection across the higher terrain as upslope flow interacts with
lingering moisture. Drier and somewhat cooler air will move in by
Wednesday evening behind the front as surface ridging builds in. A
ridge/valley temperature split will be in the offing as ridges cool
into the mid 60s with valleys dipping into the low 60s Thursday
morning.
.LONG TERM...(Thursday through Tuesday)
Issued at 346 PM EDT TUE JUL 24 2018
A series of weather systems will bring chances of showers and storms
to eastern Kentucky on Friday, and again from Saturday night through
Monday night. The best chance for rain on each of these days should
be during the afternoon and early evening hours. Temperatures should
run generally below normal, with daily highs in the low to mid 80s
and nightly lows in the low to mid 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 750 PM EDT TUE JUL 24 2018
SHRA/TSRA chances continue to be mainly east of the Commonwealth,
with only isolated to perhaps scattered coverage toward KSJS/KPBX
and along the West Virginia/Virginia state borders. Look for low
ceilings and reduced visibilities taking place again tonight into
Wednesday morning - particularly over the eastern TAF sites.
Confidence is slightly better regarding low ceilings and stratus
build-down, with fog and visibility reductions more susceptible to
any clearing that can occur. Have portrayed a stratus build-down
scenario in the eastern TAFs while going with a radiational
cooling valley fog situation further west. Both these results
should be IFR and LIFR CIG/VIS for the TAF sites late tonight and
into dawn Wednesday. This will all mix out by mid morning with
just a small chance for a shower at SJS around midday. Calm to
light winds will increase to around 5 knots out of the northwest
with arrival of a cool front on Wednesday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GUSEMAN
LONG TERM...AR
AVIATION...GUSEMAN/GREIF
Area Forecast Discussion
National Weather Service Midland/Odessa TX
646 PM CDT Tue Jul 24 2018
.DISCUSSION...
&&
.AVIATION...
VFR with a swath of mid level clouds currently sagging south
across the area. Otherwise E/NE wind will become more SE
Wednesday.
&&
.PREV DISCUSSION... /issued 219 PM CDT Tue Jul 24 2018/
DISCUSSION...As of 2:00 pm CDT Tuesday...Hey what do you know!!
It`s "cooler" out there...95 at MAF instead of the oppressive
100-105 we have been seeing for the past five days. Normal for
today is 95.
Sfc obs show the "cold" front has made it across the Rio Grande. A
band of clouds seen on vis imagery...based on cloud top temps
probably relatively flat cu are moving south thru the northern
PB. Based on earlier vis imagery it`s partially associated with a
MCV that moved south thru eastern NM this morning.
Ridge centered smack dab on the NM/AZ border will continue to
slowly retrograde thru the end of the week and become centered
over SOCAL by Friday aftn. This will allow weak impulses to drop
south thru the CWA and keep temps in relative check (near normal
which is 95 for MAF).
As for rain chances...the NAM and ECMWF are a little more bullish
than the GFS. The hi-res RAP13 and HRRR are not enthusiastic
about pop chances for tonight so they have been trimmed a bit
farther west. The best chances remain along the NM Guadalupe/TX
Davis mtns and adjacent plains. The impulse dropping south
Thursday night could spread storm activity as far east as the
central PB.
The ridge expands a bit east over the weekend before moving north
and becoming centered over the NV/UT/AZ triple point on Sunday.
H85 temps increase and with dry weather expected temps will warm
to near the century mark once again across the area with temps up
to 105 in the Trans Pecos/Rio Grande. Yay (not really).
As the ridge edges to the northwest early next week a trof will
deepen as it drops southeast out of southern Canada. This will
drag a cold front across the CWA early next week (Mon/Tue) with
the GFS a bit faster. Storm chances will increase with temps
cooling off to the mid 80s to lower 90s (per the GFS)...or the mid
to upper 90s per the ECMWF. Let`s hope the GFS pans out as it
would be nice to get some rain and cooler temps. Stay tuned!
Strobin
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 75 96 76 96 / 0 0 0 10
Carlsbad 75 98 75 98 / 20 10 20 20
Dryden 81 98 77 97 / 20 10 0 10
Fort Stockton 77 96 76 95 / 10 10 10 20
Guadalupe Pass 71 89 70 88 / 30 10 20 20
Hobbs 72 93 72 93 / 20 10 20 40
Marfa 68 88 67 88 / 30 30 20 30
Midland Intl Airport 74 96 75 96 / 10 0 10 10
Odessa 74 96 75 96 / 10 10 10 10
Wink 77 98 76 97 / 10 10 20 20
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1020 PM CDT Tue Jul 24 2018
.UPDATE...
Issued at 1020 PM Tue Jul 24 2018
Updated to include 06Z aviation discussion below.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 300 PM CDT Tue Jul 24 2018
Another pleasant day today with dry air and seasonably normal
temperatures. The clear skies will continue for much of the night,
but a sharpening mid level trough will be entering the northern
Rockies late tonight while a LLJ strengthens over the Plains.
Showers and thunderstorms will develop after midnight in the
vicinity of Bismarck and then build southward along a cold front
into South Dakota. The northern main cluster of thunderstorms will
track down I-94 for the rest of the night and push into central
and western Minnesota near dawn, reaching eastern Minnesota by mid
morning in a weakening state. It seems unlikely this activity will
be severe, but certainly some gusty winds and heavy rainfall may
accompany the leading edge of this decaying MCS.
There is rather low confidence how the rest of the day will play
out. A sharpening mid level trough will be entering western
Minnesota during the middle afternoon which will lead to strengthening
500 mb flow around 50 kts near the base of the trough. Given
enough instability in the presence of 40 to 50 kt effective shear
and sufficient convergence on the approaching cold front, a mix of
supercells and clusters would be expected with all severe weather
hazards possible. However, considerable cloud cover from earlier
convection may prevent appreciable instability from developing in
the afternoon and outflows/cold pool from said earlier day
convection could leave low level flow too weak for tornadoes. HREF
does indicate about a 50 percent chance for 1500 J/kg of SBCAPE.
This may be enough, but given the shear would prefer to see at
least 2000 J/kg. Far southern Minnesota southwestward stands the
best chance for missing the morning round, which is where SPC has
introduced a Slight Risk. CAMs seem just as unenthused about
redevelopment in the afternoon, but there are a few stronger cores
in the HRRR and the ARW along the cold front. The potential is
there for severe weather, but it will take some work that very few
days this year have been able to achieve.
The cold front will clear the CWA quickly during the evening with
the risk for storms dropping off shortly after sunset across
southern MN and western WI.
.LONG TERM...(Thursday through Tuesday)
Issued at 315 PM CDT Tue Jul 24 2018
Thursday will be the coolest in the next 7 days as the core of the
cool air mass moves overhead. The anomalous upper low that is
responsible for the cooler conditions will continue to slowly
rotate east-southeast across the Great Lakes late this week, and
begin to modify and lift over southeast Canada this weekend, and
into next week. Some instability showers or storms will be
possible Thursday afternoon over west central Wisconsin as the
system begins to modify and move eastward into southeast Canada.
Overall, it should be a dry and comfortable this weekend with
little wind as high pressure dominates.
Weather models continue to support a quasi-zonal flow aloft
next week. Some differences are noted with the next frontal
boundary by midweek, but generally, temperatures will recover to
80s, with humidity levels slowly building.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1020 PM CDT Tue Jul 24 2018
Didn`t make any significant changes from 00Z forecast package,
with reasoning similar to before. Some convection has started to
develop upstream over North Dakota, so tweaked timing with morning
convection in our area based on extrapolation of that activity and
latest guidance from the HRRR and HopWRF solutions. Otherwise,
stuck fairly close to previous timing and ceiling/visibility
values.
KMSP...Main uncertainties are with timing of activity on Thursday,
and the degree to which ceilings and visibilities will be
impacted.
/OUTLOOK FOR KMSP/
Wednesday night...VFR. Northwest wind 5 to 10 kt.
Thursday...VFR. Northwest wind 5 to 15 kt.
Thursday night...VFR. Northwest wind 5 kt or less.
Friday...VFR. Northwest wind around 5 kt.
Friday night...VFR. Variable wind less than 5 kt.
Saturday...VFR. Variable wind 5 kt or less.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
UPDATE...
SHORT TERM...BORGHOFF
LONG TERM...JLT
AVIATION...
Area Forecast Discussion
National Weather Service Pittsburgh PA
952 PM EDT Tue Jul 24 2018
.SYNOPSIS...
Showers and thunderstorms chances continue through Wednesday,
until a weak front passes. A mostly dry Thursday is expected,
while another front provides another rain chance the following
night and Friday. Near normal temperatures are expected.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 9pm, coverage of showers has actually increased over the
last hour, particularly across eastern Ohio. This was the
forecast of the HRRR several hours ago, although curiously the
latest runs of the HRRR does not show as much precipitation
anymore. Expanded coverage of likely pops, although backed off
on coverage of thunderstorms as lightning observations have
become quite isolated. Previous discussion follows.
The upper low over the Deep South is in the process of filling
and being absorbed into the mean eastern U.S. trough. Moisture
continues to flow in from the south. Instability was sufficient
to allow scattered showers to fire starting just before noon,
but lightning has been quite scarce thus far, with overall CAPE
profiles looking fairly skinny.
A shortwave and surface boundary will approach from the west,
lending support to continued showers and thunderstorms through
the night. Models are focusing the more numerous showers/higher
QPF across southwest PA and northern WV, and this is where the
bulk of the likely PoPs reside. HRRR and NAM runs have suggested
the potential for focused bands of higher QPF. While the actual
numbers in these models are likely overdone, the pattern of
isolated training heavy showers and storms is a reasonable one, and
an isolated water issue or two is possible. Severe weather will
likewise be very isolated at best, with colliding boundaries
perhaps allowing for a stronger storm. The overall lack of
instability and wind flow, plus insufficient dry air aloft, will
prevent more widespread issues. Coverage will decrease late as
instability starts to wane, albeit a bit later than typically
seen.
Low temperatures will end up a few degrees above climatology.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
The shortwave and its associated cold front will cross on
Wednesday. Showers and storms will flare up once again along and
ahead of the boundary as it crosses, with likely PoPs along and
east of a FKL/HLG line. Locally heavy downpours will remain
possible with PWAT values still above 1.5 inches, although
severe weather is not expected to be a threat. Rain chances will
linger into Wednesday night as the front exits.
Surface ridging will keep most of Thursday dry, although a
shower or two could sneak into the northwest counties by sunset.
Low pressure on the southern end of Hudson Bay will swing a cold
front our way later Thursday night. Have kept PoPs in the chance
range as moisture with this boundary will be somewhat more
limited.
Temperatures should average near or just above seasonal levels.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
The cold front will cross on Friday, with a continued chance of
scattered showers and storms. We should be able to keep Friday
night and Saturday mostly dry, although showers may eventually
need to be added north of Pittsburgh as a weak wave rotates
around the upper low, which will drift into Quebec. A general
upper troughing pattern will then remain in place into early
next week, with precipitation chances from Sunday on.
Temperatures will generally run a few degrees below climatology
through the period.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Scattered convection overnight...primarily showers after
midnight. Overall went a little more optimistic then guidance
regarding cig/vis restrictions overnight...but may need to
amend some sites to include IFR after midnight depending on how
remaining convection plays out.
Wind will veer from the ese to the wnw through the period with
the passage of the front progged for tomorrow afternoon.
OUTLOOK...
Brief sub VFR weather is possible through Wednesday with an
upper level low nearby.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
Area Forecast Discussion
National Weather Service Pendleton OR
723 PM PDT Tue Jul 24 2018
.SHORT TERM...Water vapor imagery showing a weak short wave moving
northward into the region this evening. Scattered thunderstorms
have developed over southern Oregon. Currently the storms are just
on the southern edge of our forecast area. The short wave is
expected to continue to move northeast and may push the storms
into our area for several hours this evening. At this point think
the storms would be east of Bend across the John Day highlands.
Mid and high level clouds streaming northeast across the Blues
through the evening with mostly cloudy skies then clearing
overnight. Further north across the Columbia basin and Yakima
valley skies will remain clear through the night. The weather
pattern remains similar Wednesday. Mainly clear skies in the
morning then becoming partly cloudy across the south in the
afternoon with some instability once again. Temperatures profiles
support highs within 1-2 degrees of today readings. 94
&&
.PREV DISCUSSION... /issued 336 PM PDT Tue Jul 24 2018/
SHORT TERM...Tonight through Friday...Westerly flow will generally
persist across south-central and southeast Washington through this
period. Thus conditions will be fair and dry with above seasonal
temps. A weak wave in the upper flow looks to sag into southwest
British Columbia and western Washington late Thursday and Friday.
There may be an increase in instability and mid level moisture due
to this wave, which could result in stray showers/storms over
western Kittitas county Friday afternoon. At this time, confidence
in this outcome is low and will not mention with this package.
The flow over eastern Oregon is more southwesterly, and this pattern
is expected to hold into Wednesday morning. This flow will continue
to allow mid and high level moisture to work into central, east-
central and northeast Oregon. Expect to mainly see high based
cumulus clouds and cirrus over these areas. Instability still looks
to be strong enough to cause a few thunderstorms over the Ochoco-
John Day Highlands late this afternoon and tonight. The flow over
eastern Oregon is still expected to become more westerly Wednesday
afternoon. Thus look for the deeper moisture and instability to be
pushed south of our area by late Wednesday. Will therefore continue
a fair and dry forecast across our Oregon zones Wednesday through
Friday. Temps will continue to run above seasonal through this
entire period across eastern Oregon. 90
LONG TERM...Friday night through Tuesday...An upper ridge will
shift east as it builds over WA and OR Friday night through Monday.
The ridge will keep conditions hot and dry. There will be some
limited instability each afternoon but the moisture probably will be
too limited for convection to develop. The GFS increases the
moisture Monday and indicates a few storms may develop along the
Cascades and over the northern Blue Mountains. However the ECMWF
moves the ridge more slowly and keeps eastern OR and WA dry Monday
and Tuesday. Due to lack of confidence I went with persistence and
left the forecast dry. Both models show a marine push Tuesday. This
will develop breezy winds in the typical Cascade gaps, including the
Columbia River Gorge and Kittitas Valley, and allow temperatures to
cool down. Coonfield
AVIATION...00Z TAFs...VFR conditions with variable high clouds
mainly in OR for the next 24 hours. Winds will be light and under 15
kts through the period. Winds will be strongest during the afternoon
and evenings, especially along the gaps through the Cascades and the
eastern Columbia River Gorge. 76
FIRE WEATHER...All zones will continue to observe hot conditions
and low humidity--both daytime and nighttime--for the next five
days. The westerly flow over WA and the northern half of OR is
keeping any thunderstorms suppressed to the south. However, the
southwest flow over the southern half of eastern OR has brought
enough moisture for isolated to scattered thunderstorms the past
couple of days. The biggest challenge has been where thunderstorms
will develop and how many strikes will occur. Looking at the 12Z
model runs, it was decided to issue a Red Flag Warning for Oregon
fire zone 642 which covers Grant County south of John Day and
northern Harney County. Even an isolated thunderstorm could bring a
rate of 10-15 strikes per 15 mins, similar to what was observed in
southeast OR last night. The HRRR is backing off on the thunderstorm
potential in this zone, but visible satellite loops are showing
cumulus building throughout southeast OR.
The next focus for fire weather after today will be the shortwave
trough tracking across northern WA Thursday and Friday. Any
thunderstorms will be over the WA Cascades north of Snoqualmie Pass
but will need to keep an eye if the trough digs farther south on
Friday that it will need to be added to our WA Cascade zones. Wister
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 63 98 63 98 / 0 0 0 0
ALW 68 98 67 99 / 0 0 0 0
PSC 59 100 61 101 / 0 0 0 0
YKM 59 100 61 100 / 0 0 0 0
HRI 59 102 61 102 / 0 0 0 0
ELN 59 99 61 99 / 0 0 0 0
RDM 51 97 51 97 / 0 0 0 0
LGD 55 94 54 95 / 0 0 0 0
GCD 56 96 53 97 / 10 10 0 0
DLS 63 101 64 100 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 11 PM PDT this evening for ORZ642.
WA...None.
&&
$$
94
Area Forecast Discussion
National Weather Service Reno NV
844 PM PDT Tue Jul 24 2018
.UPDATE...
Convection has decreased over all but the Western Nevada Basin
and Range this evening. Thunderstorms over the basin and range
country are producing gusty winds to near 45 mph and may be
capable of producing blowing dust. Any blowing dust may briefly
reduce the visibility along I-80 this evening east of Fernley.
The storms should dissipate after 11 pm.
Flooding is no longer a threat...although a few stronger storms
may produce brief moderate to heavy to rain along with the gusty
winds. With the flood threat waning...the Flash Flood Watch has
been allowed to expire.
&&
.PREVIOUS DISCUSSION... /Issued 211 PM PDT Tue Jul 24 2018/
SYNOPSIS...
Thunderstorms remain possible Wednesday and Thursday afternoons but
will be more isolated than previous days. A prolonged period of hot
but not record breaking temperatures is expected into next week.
Nearby fires will keep skies somewhat hazy into at least Thursday.
DISCUSSION...
Typical late July issues for the region. Here`s what we`re watching
this afternoon:
* Thunderstorms: Even with fairly favorable environment seen on
19z special sounding, storms have been slow to start. But we`re
finally getting cells with a general northeast progression. SPC
HREF guidance has storms winding down by 2100 PDT or so. Risk of
severe and localized flash flooding remains so will continue
flash flood watch with combined messaging on those hazards.
Storms have more motion, so new fire starts perhaps an increased
risk today. Have expanded storm chances Wed/Thurs northward
closer to RNO as latest guidance has a little better environment
for some isolated cells. Friday and through the weekend airmass
trends decidedly drier and more stable to storm risk will be
confined to the usual Eastern Sierra spots.
* Heat: With large ridge holding over the region through at least
mid next week, we`re looking at a prolonged period of hot
temperatures and potential heat health impacts. Each day by
itself likely won`t be record breaking but the accumulated heat
could yield issues for sensitive populations. Guidance shows 7+
consecutive days of 100+ at RNO which is quite rare. Current
record is 10 days in July 2005. One mitigating factor will be
overnight lows not being excessively warm, especially this
weekend with drier air and slightly longer nights at end of
July.
* Haze: Main fires we`re watching for smoke are near Yosemite and
southern Oregon. Latest HRRR smoke model has haze over the region
into at least Wednesday (and probably Thurs/Fri) with W/SW
transport flow. Areas of thicker smoke will depend on fire
activity, but if that happens Eastern Sierra south of Markleeville
and NE California north of Susanville are at highest risk.
-Chris
AVIATION...
Thunderstorms are the primary impact with scattered cells around the
region through about 03z/Wed. Strong outflows to 40-50 kts,
lightning, large amounts of small hail, and MVFR rains are
potential impacts. Risk of seeing storms at TVL/TRK/SVE 5-10%,
RNO/CXP 20%, MMH 40%, NFL/HTH/LOL 49%.
Depending on rainfall today, patchy ground fog is possible late
tonight in the usually prone valley spots such as TRK. Smoke and
haze from Yosemite fire will bring reduced visibilities from MEV-MMH
today and likely into Wednesday. Maybe into MVFR range at times.
Some slight visibility reductions possible in NE California near
SVE/AAT as well from fires in southern Oregon.
Airmass projected to dry out slightly Wednesday but enough moisture
may remain for a 10-30% chance of afternoon thunderstorms for
RNO/CXP/MMH and points east.
-Chris
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Blacksburg VA
920 PM EDT Tue Jul 24 2018
.SYNOPSIS...
Upper level low pressure will continue to be the primary weather
concern through Wednesday, bringing cloudy skies and scattered
showers and thunderstorms. This low pressure system will begin
to weaken and move out to provide much improved conditions for
Thursday and Friday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 915 PM EDT Tuesday...
Bands of slow moving convection within the very moist low level
southeast flow have shifted to a lingering moisture convergence
axis just west of the area, and to along an earlier outflow out
east where instability lingers near the residual front. Latest
HRRR model suggests that some of this coverage will linger
espcly east until around midnight and in spots across the
mountains where added bands could pop up and not move much per
so much moisture around. Thus keeping at least likely pops going
across the east/west a bit longer with much less coverage in
between where in between lift sources. Once the showers finally
fade out after midnight, expect to see another round of low
clouds/fog into the early morning hours pending degree of debris
clouds around. Little change to going temps with lows mostly
60s to around 70 overall.
Previous discussion as of 300 PM EDT Tuesday...
Pattern persists regarding deep upper trough that has been in
place over the Eastern CONUS for the past several days. Thus
far, the forecast area has missed the bulk of the heaviest
rainfall associated with this feature. Since the situation for
Tuesday is nearly identical to the past few days, there is not
much justification to stray too far from a persistence forecast.
Therefore, limited coverage of showers and thunderstorms right
now will increase going forward, will begin to drop around
sunset, and should be fairly isolated by midnight. Low stratus
and fog will again be possible during the overnight hours.
The pattern will begin to change some on wednesday as the trough
weakens, however plenty of moisture will still exist to
maintain some isolated coverage of showers through the morning
with again, another increase in coverage during the afternoon
hours, however, at this point, expecting said coverage to be
much less than previous afternoons.
Severe threat is minimal due to insufficient surface heating and
is mirrored by SPC outlooking only for general thunder both
days. Flooding remains the main threat for the forecast area for
today with WPC having a slight chance for excessive rainfall for
the second consecutive day, covering most of the forecast area.
While some areas are likely to see a decent amount of rain,
forecast models are not as impressive as yesterday regarding
large amounts in any particular location which is what prompted
the watch. Therefore, while any very heavy downpours occurring
in a very short period of time could still become problematic
and will be monitored for, watch issuance at this time does not
appear .
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM EDT Tuesday...
Mid/upper-level pattern undergoes transition Wednesday night through
Thursday, as the upper-level low responsible for days of showers and
thunderstorms over the eastern U.S. is expected to deamplify and
lift into the Northeastern CONUS. The mid-Atlantic and Appalachians
and the northern Carolinas then project to be in a broad cyclonic
flow aloft, on the southern periphery of a upper-level low to be
centered over northern Lake Superior. Weak surface high pressure
builds in Thursday affording a brief reprieve from cloudy and wet
conditions, before a weak shortwave trough and associated surface
cool front then progress across the region for Friday.
May still be some leftover showers early Wednesday night mainly from
the WV/VA border eastward as the upper low exits, but should trend
dry by midnight. With high pressure building in, weak to calm
surface winds for the overnight combined with rather damp ground
could prove to be a favorable environment for patchy fog even away
from river valleys. Not currently thinking dense fog but will
include patchy fog for Wednesday night for most locales.
As mentioned, looks like Thursday into Thursday night should be
generally uneventful for many. If there is one area that may see a
renewed chance for showers or thunderstorms, it`s along a lee
trough/wind shift line progged by the GFS from about Fredericksburg
VA southwest into the Reidsville NC area eastward. Prospects for
rain overall are pretty low though and will keep PoPs no higher than
lower end of Chance (25-30%) during the afternoon. Thursday night
looks dry however.
Friday looks the more active of the period, with a cold front
approaching from the west. That being said, there`s still some level
of uncertainty inherent in recent and today`s 12z guidance on timing
the front eastward. In fact today`s guidance has slowed the front
down about 6 hrs, opting for a mid-afternoon through overnight
eastward progression. There`s enough, albeit waning instability
progged between the lower GFS and the higher NAM to support at least
garden variety thunderstorms. Deep-layer wind shear profiles is
mostly unidirectional speed shear with values between 20-30 kts,
though the strongest wind shear lags the frontal zone where the
better 700-500 mb winds should lie. There`s also a considerable
amount of dry air in mid-levels that`s forecast in BUFKIT soundings,
with dry entrainment as another potential limitation. Not quite an
ideal setup for strong/severe thunderstorms given the unfavorable
timing of the frontal lift offset from peak heating and the dry
entrainment, but still enough uncertainty to at least keep that
possibility open. As the front moves into Southside and the upper NC
Piedmont, it`s low-level thermal gradient begins to slow and stall
as it moves into eastern VA, suggesting that at least some chances
for lingering overnight showers in southeastern sections is
warranted.
Temperatures overall are within a few degrees of normal for late
July.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 300 PM EDT Tuesday...
Overall a rather unsettled period for the extended, spanning from
this coming weekend into early next week.
Stalled front from late Friday night will drift eastward into
Saturday, still serving as a focus for some showers or thunderstorms
mainly south of the Roanoke River into the NC counties. On Sunday,
that stalled front then begins to return back northward in response
to a shortwave trough pinwheeling around the broad longwave trough
aloft. Should have increasing PoPs toward solid Chance/low Likely
for Sunday. Monday into Tuesday, digging trough energy into the
Mississippi Valley projects to bring a south-southwesterly tap of
Gulf moisture northeastward across the eastern third of the country.
PoPs were kept at high Chance/low-Likely range for early next week
as we may be looking at daily rain chances again. Temperatures stay
about near normal for the weekend, but then tend near to below
normal for early next week - below normal particularly on the highs
with abundant cloud cover.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 700 PM EDT Tuesday...
The deep trough over the region will continue to be the weather
maker for the forecast period. As has been the case the past
several days, variable ceilings and showers and thunderstorms
will continue to be of concern to aviation interests. Expect
most locations will be at VFR into this evening before showers
fade and low clouds/fog fill back in. This will again result in
areas of MVFR/IFR cigs/vsbys in most locations later tonight
with local sub-VFR in any of the showers this evening. Then
expect a return to VFR conditions by Wednesday afternoon before
the storms begin firing up across parts of the region. Appears
best chances of shra/tsra on Wednesday will again be over
eastern sections but enough to include a vicinity mention
elsewhere as the current axis of moisture over the mountains
pushes east during the afternoon.
Extended Aviation:
Beyond the forecast period on Wednesday, expect much of the same
during the afternoon and evening hours, however by this time
the upper low will have begun to fill and will start to become
absorbed in the prevailing flow. Coverage of showers and storms
will become noticeably reduced and a marked improvement to the
conditions should be apparent by Thursday. VFR conditions should
be fairly prevalent, however, still can not rule out some
typical summertime, isolated showers and thunder during the
afternoon hours espcly later Friday and again on Sunday. Also,
saturated soil conditions could still lead to some low
stratus/fog the next couple of nights.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JR
NEAR TERM...JH/JR
SHORT TERM...AL
LONG TERM...AL
AVIATION...JH/JR
Area Forecast Discussion
National Weather Service Tucson AZ
855 PM MST Tue Jul 24 2018
.SYNOPSIS...Expect very hot daytime temperatures through
tomorrow with record highs likely once again. Isolated to scattered
thunderstorms through midweek will mainly occur near the mountains.
More extensive thunderstorm coverage is then expected late this week
and especially this weekend as temperatures moderate closer to
seasonal normals.
&&
.DISCUSSION...Record high temperatures were handed out to several
locations this afternoon, including KTUS with 112 and KDUG climbing
to 104. A few remaining showers and thunderstorms were ongoing as of
330Z this evening, mainly east and south of the Tucson area. An
outflow boundary was also well-defined via IR satellite imagery
across Graham and Cochise Counties due to earlier thunderstorms
across the higher terrain. It is possible this boundary could
invigorate a few more showers or storms to pop up over the next few
hours as it progresses southwestward. The latest HRRR attempts to
depict this solution, but with it`s poor handling of today`s earlier
convection, confidence is not high on this scenario. Convection on
Wednesday should be just a tad more than today with the best action
again east and south of Tucson and near terrain, especially during
the peak heating of the day. With high pressure quasi-stationary for
the next 12-18 hours, high temperatures will again near record
levels during the afternoon and the Excessive Heat Warning will
remain in effect through Wednesday evening.
No updates at this time. Please see the remaining sections for
additional details.
&&
.AVIATION...Valid through 26/06Z.
SCT-BKN clouds with bases 10-15k ft AGL and isolated to scattered
-TSRA/-SHRA possible mainly E of KTUS into late this evening.
Isolated to scattered -TSRA/-SHRA will occur again Wednesday
afternoon, mainly near terrain. SFC wind variable in direction
mainly less than 12 kts through the period except for in/around
thunderstorms where gusts of 35-40 kts may occur. Aviation
discussion not updated for TAF amendments.
Be advised that very hot daytime temperatures are forecast to occur
through Wednesday. This extreme heat will cause density altitudes to
approach impact thresholds for some aircraft.
&&
.FIRE WEATHER...Isolated to scattered thunderstorms through Wednesday
will mainly be confined to locations east and south of Tucson. A
better flow pattern will allow for an increase of thunderstorm
chances for the latter half of the week into the weekend. Aside from
gusty thunderstorm outflows, 20-foot winds will be terrain driven
and generally under 15 mph. An exception is Wednesday afternoon when
occasional gusts to 25 mph should occur across the Upper Gila River
Valley.
&&
.PREV DISCUSSION...An extremely strong and deep area of high
pressure continues to dominate our weather, with an H5 value of
600dam directly overhead this afternoon. The NAEFS Ensemble shows
maximum percentile climatological values for both 500mb and 700mb
into Thursday. As such, our main short-term story will continue to
be the excessive heat at least through Wednesday.
Some debris with embedded showers west of Tucson earlier today has
slowed heating down a few degrees, but not so from Tucson eastward.
We broke a record at TUS with 110 and still have a little more time
to cook. Meanwhile, moisture is a little below average in eastern
areas, but with the best solar insolation, eastern mountains are
finally getting started with a thunderstorm or two. Limited
convective potential in valleys so storms will likely hang closer to
higher terrain. The rest of the afternoon and evening should favor
areas south of Tucson.
The high should fill a bit and start to slowly shift northwestward
as the larger scale flow loses a little amplitude upstream and
downstream over the next 72 hours. As this happens, temperatures
will fall back closer to climatology, and the enhanced easterly flow
should bring in more moisture and sharpen our thunderstorm chances
by Friday. GEFS plumes show a mean around 1.5 inches precipitable
water returning by late Friday along with a general increase in
surface based CAPE. We will be back to a near normal late July
forecast for both temperatures and thunderstorm chances by Saturday.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM MST Wednesday for AZZ501>509.
&&
$$
Carpenter/Meyer/Pegram
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Las Vegas NV
725 PM PDT Tue Jul 24 2018
.SYNOPSIS...A disturbance moving from southern Nevada toward
southwest Utah will enhance thunderstorm development through this
evening. Storms should be more inhibited across much of the region
Wednesday and Thursday, except the southern Sierra and high
mountains as a strong area of high pressure builds over the
southwest states. This will lead to dangerously hot conditions
across the Mojave Desert and southern Great Basin much of this week.
&&
.UPDATE...Thunderstorm activity appears to be gradually decreasing
this evening as sunset approaches and dynamic support moves out of
the forecast area. Still seeing some isolated to scattered activity
across Lincoln and Northern Mohave counties, and will continue to
monitor trends for any possible westward backbuilding, but at this
time thunderstorm development into far southern Nevada seems
unlikely.
Will continue to monitor trends this evening and adjust the forecast
grids accordingly, but overall the forecast is in good shape.
-Outler-
.AVIATION...For McCarran...A push of northeast winds this evening is
beginning to appear less likely, with generally light winds favoring
diurnal trends expected through Wednesday. Temperatures will be
quite hot again, with temperatures exceeding 110 degrees during the
afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...Thunderstorm activity is on the decrease but a stray
thunderstorm cannot be ruled out completely through 4z. Beyond
thunderstorm influences, generally tranquil weather is expected with
winds less than 15 knots and SCT clouds with bases above 12 kft.
&&
.SHORT TERM...through Thursday night.
Thunderstorm development has been aided today by a disturbance which
could be seen on water vapor imagery lifting from southeast
California up over southern Nevada. Most operational models indicate
this will continue moving over southeast Nevada and southwest Utah.
Convective cell movement will be to the north-northeast around 15
mph though this evening. One thing worth noting, recent runs of the
HRRR model indicate the possibility of storms around southeast Nevada
and southwest Utah producing southwestward propagating cold pool
which could bring storms down the I-15 corridor toward Las Vegas
later this evening... as we have already seen more than a few times
this month. It`s worth watching. The threat of outflow induced
thunderstorms will diminish late this evening and overnight.
The biggest impact through Thursday continues to be the excessive
heat which has been long advertised. The moisture that has provided
fuel for thunderstorms will largely be trapped under the strong area
of high pressure which will be migrating from eastern Arizona
directly over southern Nevada and surrounding states...and likely
becoming anchored the rest of the week. This will help stabilize the
atmosphere...along with boosting temperatures...but will not
completely eliminate the chance of thunderstorms over the mountains
and especially the higher terrain near central Nevada.
.LONG TERM...Friday through Monday.
Models forecast a high pressure ridge holding tough over the western
CONUS Friday through Monday. Confidence in the temperature forecast
is wavering a bit with MOS guidance now extending hot conditions
(110+ in Las Vegas) into Saturday. Although temperatures are
forecast to decrease a degree or three on Friday, some consideration
may be needed in extending the Excessive Heat Warning through Friday
and, if MOS guidance trends continue, possibly Saturday as well. The
reasoning would not be due to near record heat as covered under the
current warning but, factoring in the duration of the event and the
increasing outdoor activity heading into a weekend.
Models show a general increasing trend in moisture with PWAT values
from .75-1.00 inch across the CWA Friday to more than an inch PWATs
over the southern half of the forecast area by Monday. The areas of
forecasted deeper moisture coupled with daytime instability and the
potential for weak uplift provided by disturbances or boundaries
could fuel a few thunderstorms over the far southeastern CWA. This
would be especially true if the high center were to shift a little
bit to the east, presenting a more favorable steering flow. &&
&&
.CLIMATE...Near record temperatures are expected through
Friday this week. The table below shows the record temperatures
this week and the year recorded for McCarran (Las Vegas),
Death Valley, Needles, Barstow/Daggett, Bishop and Kingman.
RECORD HIGH TEMPERATURES (YEAR)
---------------------------------------------
TUE (7/24) WED(7/25) THU(7/26) FRI(7/27)
LOCATION ---------------------------------------------
McCarran | 117 (1942) 115(1942) 116(1943) 115(2016)
Death Valley | 126 (2006) 126(2006) 127(1933) 127(1933)
Needles | 119 (2006) 120(1943) 118(1959) 119(2016)
Barstow/Daggett | 112 (2016) 115(1975) 114(1995) 115(1995)
Bishop | 107 (2016) 107(2016) 108(1975) 108(2016)
Kingman | 107 (1928) 107(1943) 108(1934) 108(1934)
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Adair
LONG TERM...Salmen
AVIATION...Wolf
CLIMATE...Boothe
For more forecast information...see us on our webpage:
http://weather.gov/lasvegas or follow us on Facebook and Twitter