Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/12/21
Area Forecast Discussion
National Weather Service Dodge City KS
1103 PM CDT Wed Aug 11 2021
...UPDATE TO AVIATION...
.SYNOPSIS...
Issued at 1044 PM CDT Wed Aug 11 2021
WV imagery indicates a broad scale upper level trough of low pressure
stretched across the Northern Plains into the Upper Midwest and the
Great Lakes. Near the surface, a stationary frontal boundary extends
from west central Kansas into central Kansas.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 259 PM CDT Wed Aug 11 2021
An area of very subtle 850 mb cold air advection was over northwest
Kansas , behind a surface trough that was located from roughly west
of Hays ans west of DDC, near GCK. Slighlty drier dew points in the
upper 50s are noted to the west of this trough with much more rich
surface dew points in the mid 60s pooling out ahead of the trough.
The location of the trough may be off by a number of the CAMS which
had been initiating convection father north and more in and east to
west orientation through the day. The more recent HRRR runs seem to
be an outlier, by developing the storms in the moisture gradient in
the father southwest reaches of the forecast area with proliferation
with time to the northeast. However the initiation pans out the risk
period should be between and 4 and 10 pm with higher based storms
and overall lower shear values. A downburst wind environment with
potential for multiple cells creating cold pool surge anywhere along
the initiation zone.
Once the convective threat ends this evening, another mild night is
expected with most model guidance showing low 70s for overnight lows
over the higher moisture air southeast sections. A gradual shift to
temperatures as cool as round 60 degrees is likely in the far west
where the drier air will more efficiently radiate out.
The cold front now extending from northeast Nebraska into extreme
northeast Kansas is likely to be somewhere across the DDC forecast
area on Thursday, and as such, probably the focus for another round
of convection. With a sharper airmass discontinuity, the storms may
develop a little earlier - the eastern 2/3rds of so the the area is
under a Marginal risk for severe weather Thursday afternoon. The CAMS
at t hits time as one might expect are all over the place on
placement, however timing appears fairly reasonably assumed again in
the mid afternoon onward, and perhaps lingering on in the southeast
sections even longer ~beyond midnight. With increased shear/EHI
parameters there should be risk for hail and wind both Thursday.
.LONG TERM...(Thursday night through Wednesday)
Issued at 259 PM CDT Wed Aug 11 2021
In the extended the skill in determining convection becomes more
muddled, however it`s clear the temperatures will be nowhere near as
hot as the last week or so. The national model blend comes in with
fairly impressive precipitation probabilities on Friday again. The
gfs/EC/canadian models generally show a sort of post frontal moist,
still high CAPE and surface upslope environment that could easily
support convective initiation or high MCS maintenance. This
pattern may extend itself into the first part of the weekend as
temperatures moderate significantly into the low 90s or even 80s
with the loss of the hot downslope.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1101 PM CDT Wed Aug 11 2021
VFR conditions will prevail in the vicinity of all TAF sites through
late Thursday afternoon. Southerly winds around 5 to 15kt will
persist across much of southwest and south central Kansas overnight
into mid/late Thursday morning as a weak frontal boundary remains
quasi-stationary from west central Kansas into central Kansas. Light
and variable winds are likely in vicinity of KHYS due to proximity
to the boundary.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 70 95 66 90 / 10 20 30 50
GCK 67 95 63 90 / 20 20 30 40
EHA 67 93 63 88 / 0 20 30 40
LBL 68 94 64 90 / 0 20 30 40
HYS 70 98 66 87 / 20 30 40 50
P28 74 98 70 91 / 10 20 30 50
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJohnson
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Grand Junction CO
524 PM MDT Wed Aug 11 2021
.SHORT TERM...(Tonight through Thursday night)
Issued at 236 PM MDT Wed Aug 11 2021
CAM guidance has nailed the convection today as a few storms have
just fired over the San Juans and a few are now popping near Wolf
Creek Pass. Daytime heating, some minor midlevel instability, and
a slight increase in moisture has allowed these storms to fire.
Upper level winds are light so storms that are firing aren`t
moving too much but with limited moisture, briefly heavy
downpours are expected with some gusty outflow winds possible.
Convection will die down towards sunset as daytime heating begins
to wane. Smoke will remain across the area but HRRR guidance does
show concentrations lowering some as the smoke plume from Cali
shifts southward and afternoon gusts across the area provide
decent mixing. Would still expect plenty of haze, however.
CAM guidance also continues to highlight a shift of convection to
include the San Juans but also areas north to include the central
amounts and from about Vail Pass southward down to the San Juans.
Confidence is high as the HRRR/NAMNest have initialized and
performed well over the last few days. Forecast PWATs are also
expected to climb over those areas so it follows that convection
will do so as well. Steering level winds remain light under the
high so the convection won`t be moving all that much but again,
high based storms will allow some virga as gusty winds and brief,
heavy showers reach the surface.
.LONG TERM...(Friday through Wednesday)
Issued at 236 PM MDT Wed Aug 11 2021
Strong mid-level ridging located over the Great Basin will continue
to dominate the forecast through the weekend. Under this regime, the
deepest and richest monsoonal moisture will be largely kept at bay
and only encroach upon the far fringes of the forecast area,
particularly in southwest Colorado. As a result, expect most shower
and thunderstorm activity to be confined to the San Juans and
perhaps along the Continental Divide where instability and moisture
will be greatest. Elsewhere, hot and dry weather will be the rule
with only minimal chances for rain. Daytime high temperatures will
run 5 to 10 degrees above normal with the lower and desert valleys
climbing into the upper 90s to near 100 each day.
More significant changes begin to take place starting on Monday.
Ensemble guidance continues to advertise a large, broad trough
digging into the Pacific Northwest and forcing a suppression of the
ridge stuck over the Great Basin farther south towards Mexico. This
trough/ridge configuration will lead to a gradual influx of deeper
monsoonal moisture into eastern Utah and western Colorado. In fact,
the 12Z/11 EC ensemble guidance has PWATs progged to climb to ~150%
of normal across most of the forecast area through midweek -- values
that are certainly supportive of more robust and widespread shower
and thunderstorm development. Thus, after a relatively dry and quiet
stretch, confidence is increasing that another active monsoonal
surge is on the way. As has been the case for most of the summer,
flood prone areas and our most recent burn scars (especially Grizzly
Creek, Pine Gulch, Pack Creek, etc) will be particularly at risk for
heavy rain and potential flash flooding. Given increasing moisture
and cloudiness, temperatures will be trending cooler during the
first half of next week.
As was previously mentioned, how long this upcoming monsoon episode
lasts is still uncertain. Looking at the latest WPC 500mb height
cluster guidance, there are two distinct camps depicting the
evolution of the trough over the Pacific Northwest within the 3
major ensemble systems (EPS, GEFS and CMCE). One camp results in a
more progressive (and thus a drier solution); the other results in
unsettled weather persisting through the end of next week. At this
point the odds for either solution are about 50/50, but there`s
still plenty of time to sort out the details in the 7-10 day
timeframe.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 518 PM MDT Wed Aug 11 2021
Convection along the southwest San Juans will diminish within the
next hour with mainly clearing conditions and relaxed winds
overnight. Inversions may trap smoke over lower valleys tonight
with some MVFR conditions possible due to reduced visibility by
sunrise. Otherwise, high pressure overhead will support decent
diurnal mixing, and thus, breezy afternoon conditions for most
TAF sites. A few isolated to scattered thunderstorms are expected
to develop over higher terrain along the central and southern
ranges Thursday afternoon possibly impacting DRO, TEX, GUC, and
ASE. Gusty outflow winds will be the primary threat.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...TGR
LONG TERM...MDM
AVIATION...ERW
Area Forecast Discussion
National Weather Service Lincoln IL
902 PM CDT Wed Aug 11 2021
.SYNOPSIS...
Issued at 203 PM CDT Wed Aug 11 2021
Wet and unsettled weather will remain possible through Friday
ahead of a sagging cold front. Cooler and drier conditions will
return this weekend in wake of frontal passage. Nevertheless, hot
and humid conditions will return by the middle of next week, and
will accompany thunderstorm chances.
&&
.UPDATE...
Issued at 902 PM CDT Wed Aug 11 2021
Updates have been made to increase PoPs mainly Knox, Stark, and
Marshall Counties as thunderstorms have been developing along a
boundary from northeast IL into southeast IA, well ahead of an
earlier zone of convection earlier in the evening. Strong
instability of 3000-3500 J/kg MLCAPE in this zone could produce
strong storms, although higher potential for severe storms resides
more in northern/northeast IL where shear is stronger and
satellite imagery indicates more lift from a shortwave. Overnight,
CAM models have been fairly consistent in depicting more
widespread thunderstorm activity developing and sinking southward
across central IL aided by a low level jet. Timing in intensity of
the feature has varied widely.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 203 PM CDT Wed Aug 11 2021
Deep convection has developed across central Wisconsin this afternoon
along and ahead of a surface cold front. As this front drifts
southeastward into northern Illinois this evening, some questions
remain as to whether this activity will be sustained. The main
limiting factor will be insufficient deep-layer shear as mid-
level flow begins to weaken.
Any renewed convective activity this evening will likely be
triggered by a subtle mid-level shortwave impulse that rides
above an intensifying LLJ. The magnitude and direction of the
shear vectors will play a key role in determining convective mode
this evening across central Illinois. The latest RAP analysis
(19z) suggests bulk shear vectors will be oriented roughly
parallel to the line of forcing, meaning that convection should
grow upscale into a linear MCS. However, relatively weak 0-3km
shear magnitudes (< 25 kts) means that the cold pool from this
linear MCS would struggle to stay balanced, and would ultimately
become outflow dominant. This all adds us to a raggedy line of
storms north of I-72 later this evening. Still, bouyancy will
likely be sufficient enough to yield an isolated severe wind
threat, as a few downdrafts along the line punch down to the
surface.
A lot of forecast uncertainty remains for Thursday as convective
debris likely keeps central Illinois capped through late morning.
If clouds can break by afternoon, there will likely be enough
bouyancy ahead of the cold front to support strong-to-severe
thunderstorms. If clouds linger, the capping inversion will likely
remain in place and suppress convective initiation as the front
slowly sags southward across the outlook area.
Despite mid 70s dewpoints pooling ahead of the front Thursday
afternoon, clouds will likely hold temperatures down into the
upper 80s. This should keep heat index values below advisory
criteria on Thursday, but they will still be in the mid 90s.
The cold front will begin to push south of I-70 by Friday. With
similar CAPE/Shear profiles in place as Today and Thursday, the
threat for isolated severe storms remains possible Friday ahead of
the front. A temperature gradient will be present across the
region on Friday afternoon, with low 80s behind the front, and
upper 80s ahead of it. At this time, we do not anticipate a heat
advisory for Friday either.
.LONG TERM...(Saturday through Wednesday)
ISSUED AT 203 PM CDT Wed Aug 11 2021
Cooler and drier weather conditions will work into the Midwest
this weekend in wake of frontal passage. Surface high pressure
will then continue to build across the region through early next
week, suppressing the weather pattern. By Tuesday, winds will veer
southerly as surface high pressure departs toward the
Appalachians. This will allow temperatures and humidity to surge
upward once again, and will mark the return of thunderstorm
chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 659 PM CDT Wed Aug 11 2021
Potential thunderstorm activity overnight is the main focus for
TAFs at this time. Significant uncertainty remains for
development of a squall line that propagates southeastward into
central IL late in the evening or overnight, so have included VCTS
in TAFs starting 03Z-06Z, however amendments may be needed for the
evolution of this feature. By morning, scattered SHRA/TSRA over
the area should begin to dissipate, with precipitation likely to
end by 15Z-18Z. Any thunderstorms could have MVFR cigs and IFR-
MVFR vsby. Wind shear is anticipated from 05Z-12Z mainly KSPI-
KBMI-KPIA area due to 40 kt SW wind at the 2000 foot level AGL.
Otherwise, surface winds from the SW should predominate through
the period, diminishing to 08-12 kts this evening, then increasing
to 10-12 kts with higher gusts expected again by 18Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SYNOPSIS...MJA
SHORT TERM...MJA
LONG TERM...MJA
AVIATION...37
Area Forecast Discussion
National Weather Service Northern Indiana
820 PM EDT Wed Aug 11 2021
.SYNOPSIS...
Issued at 820 PM EDT Wed Aug 11 2021
More storms are likely at times tonight through Friday before
cooler and dry conditions prevail this weekend. High temperatures
will be around 90 Thursday with heat indices around 100.
&&
.SHORT TERM...(This Evening through Thursday night)
Issued at 255 PM EDT Wed Aug 11 2021
Convective complex currently moving exiting eastern CWA and will
to move east of the area shortly. HRRR seems to be best among the
HREF members in handling this early afternoon convection so will
lean that way for potential redevelopment tonight where ongoing
convection in WI still expected to intensify this afternoon in the
presence of highly sheared environment ahead of approaching mid-
level short wave. Still anticipate organization into a more linear
complex as it moves down into SE WI...NE IL...SW lwr MI...with
plenty of uncertainty in severe threat for our area after being
worked over this afternoon. In the wake of whats left of nocturnal
complex tonight will once again see very warm...humid airmass in
place and with decreasing clouds expect ample destabilization in
the daytime hours leading to convective initiation to our west and
tracking E/SE along baroclinic zone to potentially impact our
area late Thursday/Thursday night. Hot and humid conditions
expected again on Thursday with highs near 90 and dewpoints in the
low to mid 70s will have heat indices approaching 100 in SE CWA
so will consider having advisory in effect during the afternoon-
early evening.
&&
.LONG TERM...(Friday through Wednesday)
Issued at 255 PM EDT Wed Aug 11 2021
Forecast period to begin with final push of frontal boundary through
our area on Friday. Timing will dictate if any diurnal instability
can develop in SE CWA before front moves through. Latest trends from
deterministic models in line with SREF in early arrival for frontal
passage that should preclude any threat for strong to severe storms.
Canadian high pressure building in behind this front will bring much
less humid conditions to the region as dewpoints drop into the 50s
Saturday. Pleasant...dry weather continues into the beginning of
next week with precip chances arriving toward the end of the period
as remnants of TS Fred drift northward through the Appalacians.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 815 PM EDT Wed Aug 11 2021
Next shortwave and associated weak frontal boundary will cross the
area tonight with another round of storms. Timing is becoming a
bit clearer but there is still some uncertainty based on
inconsistencies among latest CAM`s. Also low confidence on
coverage and severity of any thunderstorms...particularly at KFWA
given late arrival and overall weak forcing. Will therefore
continue with just a VCTS mention. Slightly higher confidence at
KSBN and may introduce a TEMPO TSRA later. Some MVFR ceilings may
be possible behind the rain Thu morning but confidence is too low
to include with this package.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 2 AM EDT Thursday for LMZ043-046.
&&
$$
SYNOPSIS...AGD
SHORT TERM...JAL
LONG TERM...JAL
AVIATION...AGD
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Area Forecast Discussion
National Weather Service Marquette MI
752 PM EDT Wed Aug 11 2021
.SHORT TERM...(This evening through Thursday)
Issued at 408 PM EDT WED AUG 11 2021
GOES imagery and RAP analysis show a cold front moving through Upper
Michigan right now with ongoing convection south and east. While CAM
solns are a bit scattered, add`l clearing and heating across the
west and central should aid in some more development after 4. Latest
RAP suggest MLCAPE values between 500 and 1000 J/kg, with 150 SRH
and up to 50kts of 0 to 6km bulk shear. Latest HRRR does suggest
some isolated development as well across the central with GOES-vis
showing some agitated cu, but no reflectivity yet.
Tonight, cold front will move through Upper Michigan bringing some
relief to the humidity values. Upstream in MN, Tds have quickly
fallen into the 40s, with GOES WV imagery showing broad subsidence
as well. Pressure rises and CAA will bring some gusty winds,
especially across the Keweenaw, where some values late
tonight/tomorrow morning will approach 30mph.
Tomorrow, it will be a breezy day behind the fropa tonight with
gusts to around 25 mph across the central, closer to 30mph possible
for the Keweenaw. Waves will increase through the day, leading to
some beach hazards concerns east of Marquette by the evening. Temps
may initially climb through the early aftn, but continued CAA will
begin to cool things off by the evening.
.LONG TERM...(Thursday night through Wednesday)
Issued at 128 PM EDT WED AUG 11 2021
A persistent upper level low will continue to slowly meander over
the Hudson Bay, and eventually move to th east over the north
Atlantic this coming weekend. As this does so, upper level ridging
will become appartent over the central CONUS, ecompassing the Great
Lakes in the process with warmer temperatures. Temperatures will
start off slightly below seasonal average on Friday before gradually
warming to above season normals from the late weekend toward the
middle of next week. Due to the persistent upper level ridge, we can
expect mostly dry conditions for the medium to extended forecast
period as well.
The extended forecast will begin with a cold FROPA exiting the area
by Thursday night across our eastern zones in the cwa, and CAA
beginning to swing down from the north. This will bring much needed
relief with regard to the persistent warm and humid conditions the
Upper Michigan area has observed the last several days. By Friday,
strong CAA aloft via nw flow will keep temperatures very
comfortable. 850mb temperatures will bottom out near 5C over the
Keweenaw, and warm gradually through the day to near 10C. Despite
the cool temperature aloft, the surface high pressure and mostly
sunny conditions will allow surface temperatures to warm into the
60s to lower 70s by late afternoon. This would make the daytime
highs for Upper Michigan on Friday on par with what several areas
have had as overnight lows for the past several days. This will make
it a great start to the weekend as conditions look to remain
tranquil and dry.
Gradual warming because of a building upper level ridge over the
central CONUS will spread to the east to include Upper Michigan, and
the surface high pressure will continue to keep the area dry. Expect
surface temperatures to increase daily through the middle of next
week with daytime highs reaching the upper 70s to middle 80s, and
little to no precipitation to occur.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 752 PM EDT WED AUG 11 2021
With drier air flowing into the Upper Great Lakes, VFR conditions
will prevail at KIWD/KCMX/KSAW thru this fcst period. Westerly winds
will generally be gusty at KCMX throughout, but particularly during
the day on Thu when gusts up to 30kt are expected. Winds at
KIWD/KSAW should gust to around 20kt during the day.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 408 PM EDT WED AUG 11 2021
A cold front passing over Lake Superior tonight will bring some CAA
and pressure rises with gusty westerly winds. While there is some
question as to the stability of the air mass over the lake, there is
a chance for some gale force gusts to around 35 knots along the
Keweenaw Peninsula in north-central Lake Superior late tonight, and
then again tomorrow afternoon. The best chance for this will at the
higher observation platforms. With the cooler airmass aloft,
unstable conditions will help support winds near 20 knots across the
lake through Friday afternoon. From there, high pressure building
into the region is expected to keep winds calm and under 20 knots
into next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 10 PM EDT this evening for MIZ014.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...BW
AVIATION...Rolfson
MARINE...JAW
Area Forecast Discussion
National Weather Service Portland OR
342 PM PDT Wed Aug 11 2021
.SYNOPSIS...High pressure will continue across the region through
Friday leading to hot and dry weather. An excessive heat warning is
in effect from noon Wednesday to Saturday evening. The upper ridge
will shift east this weekend with a slight cooling trend starting
Saturday and continuing into early next week.
&&
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...The weather remains quiet
but hot under the influence of a 594 dam 500hPa ridge building into
the area from the eastern Pacific. As of 2p.m. this afternoon,
temperatures have already climbed well into the 90s. With surface
heating continuing over the course of the next few hours, we would
not be surprised if many Willamette Valley locations reach/surpass
100F today. In addition, the overnight recovery is expected to be
less tonight, with temperatures in densely-populated, urbanized areas
struggling to fall below 70 degrees (rural locations still only
dipping into the middle to upper 60s) by daybreak. This positive
feedback cycle continues tomorrow, with temperatures potentially
warming more than today (given the higher overnight lows) provided
smoke and haze advected into our area from fires to our north and
east doesn`t trim them back a bit. Confidence is low in the exact
magnitude and duration of the heat, but the models continue to depict
a strong signal that temperatures will be significantly warmer (15+
degrees F) than normal. The ECMWF and GFS still agree that 850mb
temperatures will warm to ~25C by tomorrow afternoon, and the NBM
continues to suggest the probability of exceeding 100F tomorrow at
PDX is around 70%. Friday looks very similar, though perhaps a degree
or two cooler according to both MOS and NBM guidance. Still, the heat
will be oppressive, especially for vulnerable populations such as the
elderly, the very young, and those without air conditioning. In fact,
heat stress is forecast to peak during the Thursday night into Friday
timeframe since we`ll be multiple days into the event.
Friday, the mention of thunder in eastern Lane and Linn counties
stands to cover the potential for a few elevated cells that will form
from orographic effects along the spine of the Cascades. This mention
is only slight, since (1) instability doesn`t look overly impressive
on this side of the crest, (2) the bottom of the unstable layer
(known as the level of free convection, or LFC) is forecast to be
right around the top of the Cascades, and (3) the mid to upper-level
steering flow has a westerly component that will drive convection
quickly east of the crest (the edge of our area of responsibility).
Still, we believe the mention is warranted given the weak 1.5PV
tropopause fold forecast by the NAM, along with the NBM and SREF`s
15-25% forecast chance for thunder in the area. Some concern even
exists in elevated, nocturnal convection tomorrow (Thursday) night in
the Lane County Cascades and foothills, but most high resolution
models - with exception to the more-aggressive HRRR - suggest that
anything moving NW into Lane County overnight will be fizzling, and
hence only capable of dropping a few sprinkles through the dry
boundary layer. -Bumgardner
&&
.LONG TERM...Saturday through Tuesday night...After a few days of
very hot weather, Saturday will initiate a pattern shift that will
bring some relief to the area. On Saturday, vertically stacked
onshore flow will become dominant, which will bring in cooler air
from the North Pacific. The change to onshore flow stems from the
shift of the upper level high to the east, and a weak low forming
aloft over the Pacific. This low is accompanied by elevated
southwesterly winds in the jet stream aloft around 35,000 ft. Because
of the onshore flow, relief from smoke may occur as it may be pushed
out of the area from nearby fires. This of course depends on whether
or not there are new starts that may occur in the previous days. By
Sunday, a broad low that currently sits over the northern Gulf of
Alaska will widen and begin its slow advance southward along the B.C.
coast. As the low aloft moves southeast, a shortwave within the flow
will move over the area beginning Sunday morning. This shortwave will
bring more cool air to the area and even a slight chance for some
rain showers along the northern portions of the forecast area.
Models have varied quite a bit in regards to the timing and location
of the precipitation so confidence is low. There is a chance that if
the parent low stays further north, that the rain could miss our
area completely. In contrast, if the low dips further south,
potentially more of the area could experience rain. Have decided to
keep PoPs and accumulation low to represent the uncertainty. Long
term models show a pretty consistent pattern in regards to the
overall synoptic pattern with the main differences lying in the
intensity of the system. The GFS is currently the stronger and more
southerly pattern, while the ECMWF and Canadian keep a bit more
conservative strength and trends to the north over interior Canada.
Even with these differences, a similar overall outcome is
expected...cooler temperatures, stronger onshore flow, and a slight
chance for rain in the north on Sunday and Monday. -Muessle
&&
.FIRE WEATHER...Strong high pressure over the northeastern Pacific
will gradually drift eastward through Saturday. A subsidence
inversion will lower to 2500-3000 feet Thursday and Friday bringing
poor humidity recovery for the Cascades and Coast Range ridges.
Additionally, cut-off low pressure moves north Thursday and Friday
bringing significant instability and strong ventilation potential.
Friday also brings an elevated thunderstorm threat for the Central
Cascades.
&&
.AVIATION...High pressure over the region will result in
predominantly VFR conditions areawide through 00z Friday. The
main exception to this will be along the coast where a southerly
wind reversal and accompanying fog and low clouds will spread
northward up the coast. This will likely result in a mix of IFR
and LIFR conditions pushing into KONP between 06-12z Thursday.
There is a chance it could push all the way northward and impact
KAST between 12-18z Thursday, but nearly all model guidance
suggests it will fall short and this does not seem unreasonable
given the strength of the current high pressure ridge overhead.
Smoke from the wildfires burning in the Oregon Cascades will
continue to primarily impact eastern Lane, Linn and Marion
Counties over the next 24 hours. The latest HRRR smoke model
does suggest some smoke from BC/WA wildfires will drop
southwestward through the Columbia River Basin and begin to
impact the Columbia River Gorge and northern Willamette Valley
between 18z Thursday and 00z Friday. Do not expect this to bring
IFR visibilities at this point based on limited smoke upstream,
but we might see surface visibilities drop into the 5-9 mile
range in a worst case scenario. Confidence is not terribly high
that these visibilities will come to fruition, though given
smoke coverage is still somewhat limited across eastern
Washington and southern British Columbia.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...High pressure aloft will result in light
winds and VFR conditions through 00z Friday. Some smoke from
BC/WA wildfires will begin to spread westward through the
Columbia River Gorge between 18z Thursday and 00z Friday and may
result in surface visibilities falling into the 5-9 mile range.
Do not expect this to bring IFR visibilities at this point based
on limited smoke upstream, but we might see surface visibilities
drop into the 5-9 mile range in a worst case scenario. Confidence
is not terribly high that these visibilities will come to
fruition, though given smoke coverage is still somewhat limited
across eastern Washington and southern British Columbia. /Neuman
&&
.MARINE...High pressure over the northeast Pacific and thermally
induced lower pressure shifting inland today will result in
breezy northerly winds decreasing over the next 24 hours. There
could be a few isolated spots with gusts to 21 kt during the
remainder of this afternoon and early evening, but not expecting
wind gusts this strong to be widespread enough to necessitate a
Small Craft Advisory.
A southerly wind reversal will move northward up the coast
overnight and bring areas of fog and a brief burst of 10 to 20
kt southerly wind gusts, primarily to the waters within 10 to 20
NM of the Oregon coast. It remains unclear if these gustier
southerly winds will make it all the way to the south
Washington coast overnight. Light southerly winds should then
more or less develop across all of the waters Thursday into
Friday and persist through the weekend. These southerly winds
are expected to remain well below Small Craft Advisory wind gust
thresholds of 21-33 kt. Expect seas to climb into the 8 to 10 ft
range over the next 24 hours as an incoming northwesterly swell
pushes into the waters. Seas should then gradually decrease
thereafter and drop below 5 ft for the weekend. Seas may increase
slightly early next week after a weak front drops southeastward
across the waters late Sunday into early Monday. /Neuman
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 10 PM PDT Saturday for Cascade
Foothills in Lane County-Cascades in Lane County-Central
Coast Range of Western Oregon-Central Columbia River Gorge-
Central Willamette Valley-Coast Range of Northwest Oregon-
Greater Portland Metro Area-Lower Columbia-Northern Oregon
Cascade Foothills-Northern Oregon Cascades-South
Willamette Valley-Upper Hood River Valley-Western Columbia
River Gorge.
Red Flag Warning from 11 AM to 10 PM PDT Friday for Mt. Hood
National Forest West of Cascade Crest.
Red Flag Warning from 11 AM Thursday to 10 PM PDT Friday for
Central Oregon Cascade Foothills-East Slopes of the
Central Oregon Coast Range-Willamette National Forest.
WA...Excessive Heat Warning until 10 PM PDT Saturday for Central
Columbia River Gorge-Greater Vancouver Area-I-5 Corridor
in Cowlitz County-South Washington Cascade Foothills-South
Washington Cascades-Western Columbia River Gorge.
Red Flag Warning from 11 AM to 10 PM PDT Friday for Eastern
Gifford Pinchot National Forest Mt Adams Ranger District-
Extreme South Washington Cascades and Foothills.
PZ...Small Craft Advisory from 6 AM to 10 AM PDT Thursday for
Columbia River Bar.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
308 PM MDT Wed Aug 11 2021
.SHORT TERM...(This evening through Thursday)
Issued at 239 PM MDT Wed Aug 11 2021
Currently...Isolated thunderstorms have formed over the eastern San
Juans and srn Sangres, as mid level moisture has begun to increase
in these areas this afternoon. Various CAMs suggest additional
convection may develop eastward along the NM border in Las Animas
County by 22z, spreading eastward into Baca County 22z-02z, as low
level convergence strengthens near the old frontal boundary
stretching from nern NM into sern CO.
Tonight... Most convection should end fairly quickly this evening,
as better moisture and mid level forcing remain to our south through
the night. Should see clouds decrease enough overnight for
seasonably cool min temps, though drier air over the nrn half of the
area may allow high mountain valleys in the central mountains to
drop into the 30s by early Thu morning.
Thursday...Weak upper wave drifts eastward across CO, while new
surface cold front drops south through the plains, becoming nearly
stationary near the Arkansas River by late afternoon. Old cold
front/surface trough will also still lie somewhere near the srn CO
border as well. In general, felt the 18z HRRR solution was fairly
reasonable, suggesting convection will fire on the plains near/just
behind the cold front by mid-afternoon, with additional activity
along the surface trough over the far se by late day. Still some
spread in model solutions though, as NAM is generally along/north of
the Palmer Dvd with the main convective area, while the GFS is
farther south in NM. Deepest moisture/instability forecast to be
over the far sern plains, where CAPE in the 1-2k j/kg range could
lead to some stronger storms, despite the absence of much in the way
of 0-6km shear. Farther west over the mountains, mainly isolated
activity, though areas near the Continental Divide will see slightly
better storm coverage. Max temps north of the front will cool
slightly versus Wed numbers, while the remainder of the area sees
very little change.
.LONG TERM...(Thursday night through Wednesday)
Issued at 239 PM MDT Wed Aug 11 2021
Friday...
As an upper-level trough moves off far to the northeast, an upper-
level high pressure system will begin to build in from our
southwest. This will cause some disturbance to the flow aloft,
allowing vorticity maxima to propagate over our area and assist in
the development of showers and thunderstorms. Scattered to likely
thunderstorms will form over the mountains in the afternoon, mainly
over parts of the Continental Divide, with scattered storms expected
over the rest of the area throughout the rest of the day. Models are
resolving 700-900 J/kg of CAPE over most of the mountains, and over
1300, on average, over the Palmer Divide and further east. Surface
flow is also expected to have a consistent upslope component over
most of the eastern plains, which will further assist in providing
lift. The vast majority of storms will stay over the higher terrain,
but as the upper-system tracks east conditions could allow for a few
storms to form and/or propagate over the eastern plains later in the
day. Shear is not expected to be very strong, so the current severe
threat is on the low side, with the main concern being for flash
flooding conditions, especially over burn scars.
Saturday-Wednesday...
Starting into the weekend, as the closed upper high sits near the
Great Basin, and mid-level low pressure center will form to our
southwest as well, funneling in much more moisture to the area. This
gives us a more typical monsoon moisture set up, and precipitation
coverage is expected to increase on Saturday and Sunday. Moisture
will continue to funnel in through the beginning of next week as the
low begins to shift the upper-high to the west, which could create
more widespread showers and thunderstorms. Overall, the forcing is
mainly centered over the mountains. With a distinct lack of forcing
over the eastern plains, they should remain largely free of storms.
However, should things play out as the long-term guidance suggest,
the first half of next week could be busy with heightened flash
flooding concerns.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 239 PM MDT Wed Aug 11 2021
VFR conditions expected at all taf sites the next 24 hrs, as smoke
layer across the region continues to gradually thin. Isolated
afternoon/early evening convection across the srn mts and along the
NM border will slowly diminish this evening, and any impacts at taf
sites should be limited to briefly gusty outflow winds at KALS and
KPUB. On Thursday, cold front drops south through the plains,
bringing enhanced chances for thunderstorms at both KCOS and KPUB
after 20z.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...GARBEROGLIO
AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Reno NV
305 PM PDT Wed Aug 11 2021
.SYNOPSIS...
Above-average temperatures will peak this week as high pressure
builds into western Nevada through Saturday. Moisture and
instability will continue to expand across the Sierra and western
Nevada this week as well. These ingredients will usher in the
return of thunderstorms across the region through the end of the
week into the weekend. Variable smoke and haze will persist as
wildfires continue across the West.
&&
.SHORT TERM...
A broad area of high pressure aloft extends from a close high
offshore the Pacific Northwest southwest into the Four-Corners
region and northern Mexico. During the course of this week, a
closed upper high will strengthen over the Great Basin as a nearly
stationary upper low lingers over the Eastern Pacific west of the
CA coast. The resulting interaction of these two systems will
allow monsoonal moisture to permeate further northwest and north
across the Sierra and into western Nevada through the shorter-term
period. As the upper high builds and spreads west into CA through
tomorrow, area temperatures will continue to heat up to around
5-8 degrees above seasonal normals through this week. The rising
temps will allow the return of sufficient instability to increase
the risk of thunderstorms each day mostly over the Sierra and far
western NV. Outside the gusty outflows from these developing
storms, winds will remain generally light over the region. A
short-lived zephyr wind will still make its summertime appearance
late each day before pushing east off the Sierra into far western
NV basin areas.
* THUNDERSTORMS: Coverage is going to favor the Sierra crest this
evening (south of Lake Tahoe) and the Sierra/Lassen County
convergence into northwest NV tomorrow as an upper wave moves
northwest along the CA coast through Thursday evening. Mid-
level storm flow will be east-southeast and tend to push storms
to the west side of the crest with weak forcing aloft to enhance
a few more energetic storm cells. However, low- level outflows
could instigate a few storms close to the Hwy 395 corridor in
Mono County into the far western NV. As the upper wave moves
further into northwest CA, sufficient moisture and CAPE will be
present to spread the risk of isolated storms into northeast
CA/northwest NV tomorrow into Friday morning. By Friday into
Saturday, warmer air infiltrating the mid-levels, with no
dynamic forcing to trigger storm development other than the
interaction with the complex terrain, will keep storm coverage
mostly isolated across the region. PWATs will range between
0.75"-0.85" Friday and Saturday with some hybrid storms becoming
more capable of producing locally heavy rains with possible
debris flow impacts to area burn scars. Gusty outflow winds to
40 mph remain a real possibility with high storm bases and
enhanced DCAPE values reaching mostly above 1000j/kg.
* HEAT AND SMOKE: Temperatures will be pushing 100 degrees for
warmer lower valleys and close to 90 in the Sierra valleys.
ECMWF Shift of Tails guidance revealed that Minimum Temps
overnight tomorrow could reach the 0.8 to 0.9 percentile for
most areas over the northern Sierra and Washoe County. While the
above-average temperatures are not a new thing for this time of
the year, ongoing smoke and depressed air quality can
exacerbate the potential for heat health symptoms over those
areas affected by higher temperatures and denser smoke. There
will be a potential for additional smoke transport into areas
east of the Sierra as late-day zephyr breezes develop to the lee
of the northern Sierra ridges. -Amanda
.LONG TERM... (Saturday and beyond)
Ensemble simulations continue to show a weakened area of high
pressure withdrawing eastward after Sunday. An upper short wave
that will advance into and lift northeast across the Pacific
Northwest and northern Rockies early next week should increase a
dry-stable southwest upper flow over CA/NV. The same long-range
model/ensemble guidance still points to an upper short wave of
some form entering the forecast picture early next week. Some
uncertainty surrounds the general depth and timing of the incoming
upper wave as ensemble cluster predictions show differing
scenarios. European ensemble guidance favors a more split flow
aloft while increasing shares of the GFS ensemble members lean
towards a more symmetric structure of forcing and momentum needed
to boost gusty afternoon winds that could reach more critical
levels. The increasing and drier southwest upper wind flow will
bring a decrease in thunderstorm coverage going into next week.
The change in the large-scale winds and the daily storm outflow
potential will only bring an increased uncertainty to any
predictions of smoke and haze coverage and AQI impacts in the
coming days. -Amanda
&&
.AVIATION...
Periods of smoke and haze at the surface and aloft will impact
terminals in the Sierra and western NV for the next couple days (and
likely well beyond) as the Dixie wildfire remains active.
Terminals across western Nevada and eastern CA could range between
VFR and MVFR through Thursday as smoke transport/mixing varies; the
possible exception is south and west of KSVE closer to the Dixie
Fire where periods of IFR conditions are on the table. HRRR smoke
simulations keep most of the smoke out of the Tahoe Basin and
eastern Sierra again through Thursday although slantwise visibility
will likely be degraded.
Low afternoon-evening thunderstorm potential (10-20% chance) will
spread from the Sierra south of Hwy 50 near/west of the crest today
to northeast CA and far western/northwestern NV Thursday through
Saturday. Thunderstorms are most likely to be rather garden variety
with localized moderate-heavy rain, pea-size hail, and wind gusts up
to 30-40 kts. -Snyder
&&
.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 Seattle WA
853 PM PDT Wed Aug 11 2021
.SYNOPSIS...An upper level ridge will continue to build and
strengthen over Western Washington through the rest of this week,
resulting in very hot temperatures. Offshore flow develops but
eases by Friday, with cooler marine air returning to the coast. A
weak weather system is still expected to move into the region over
the weekend, with cooler conditions and possibly some light rain
chances for the start of next week.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...Forecast remains on track
this evening. Previous short term discussion follows.
The heatwave is off to strong start with temperatures as of 2PM
in the low 90s for areas in the Interior. With overnight lows in
the mid 60s not much relief is expected to occur. High
temperatures Thursday and Friday are expected to be even higher
with highs in the mid to upper 90s likely for the Interior. There
could be some slightly stronger onshore flow by Friday that will
keep the coastal areas significantly cooler. With the hot
temperatures and little recovery during the overnight an Excessive
Heat Warning remains in effect through Friday for much of the
area. While Saturday will still be hot we are expecting better
night time recoveries due to increased onshore flow. While sky
conditions will remain mostly cloud free, hazy skies are likely,
especially along and near the Cascades. This haze will be mostly
due to smoke moving into the area from fires to our north and
east. This smoke is expected to stay mostly aloft. While models
such as the HRRR smoke are showing noticeable concentrations at
the surface, it is believed that these concentrations are over
forecasted due to the model over mixing the entire atmosphere.
That said, areas of Whatcom County and Lewis Counties could see
smoke concentrations that would bring the AQ down to Sensitive for
Unhealthy Groups, there is high uncertainty with that. And we
will be consulting with our AQ partners if trends appear to
change.
Butwin
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...A return to cooler and
moister weather is expected through much of the long term forecast
period. With the upper level ridge being forced out of the area by
a weak weather system and then by a series of little shortwaves
moving through the area. While there is a chance of some rain
Sunday into Monday it is expected to be very light, with areas
receiving only a few hundredths of an inch. Areas at the higher
elevations of the Cascades and Olympics could see up to a couple
tenths but this will do little to lessen the fire weather dangers.
Butwin
&&
.AVIATION....Northwesterly upper level flow overnight, with
weakening onshore flow becoming offshore late tonight. Low level
winds through much of the interior will remain northerly at 10 kt
this evening, easing to around 6 kt by 08z. The atmosphere
remains dry with generally clear skies, though some elevated
smoke/haze may pass overhead at times. VFR conditions will
generally prevail, though some brief IFR marine stratus may
redevelop into KHQM for a few hours toward daybreak Thursday
morning.
KSEA...Clear skies and VFR conditions will persist through
Thursday. Northerly winds continue, with any gusts tapering and
winds easing after 08z. Expect another round of northerly winds
increasing to around 10 kt with Thursday afternoon and evening.
&&
.MARINE...Persistent northerly winds at small craft advisory
levels and building swell over the outer coastal waters through
early Thursday morning, with the small craft advisory remaining in
effect for the outer waters through 11 AM. The weak onshore flow
will transition to easterly flow late tonight and persist through
much of the day Thursday. Models have been consistently showing
weak onshore flow through the Strait of Juan de Fuca redeveloping
late Thursday evening. This will become more established Friday,
with southerly flow returning to the coastal waters. Seas this
weekend remain 4 to 5 ft, dominated by a west swell.
&&
.FIRE WEATHER...Red Flag Warning remains in effect for Thursday
and Friday for the Cascade zones (658 and 659) due to dry and very
unstable conditions. Expect light offshore flow to develop tonight
and take hold into Thursday across most of the region and daytime
humidities to dip close to critical values during the afternoon.
Modest recoveries are expected Thursday night for many locations,
but a strengthening subsidence inversion that is expected to lower
to around 2500 or 3000 ft will likely yield very poor recoveries
for elevations above this. Elsewhere, while hot and dry conditions
are expected, it is not anticipated that conditions will be severe
enough to warrant a westward expansion of the warning at this
time. Cooler and more humid air arrives late in the weekend.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Excessive Heat Warning until 7 PM PDT Saturday for Bellevue and
Vicinity-Cascades of Pierce and Lewis Counties-Cascades of
Snohomish and King Counties-Cascades of Whatcom and Skagit
Counties-East Puget Sound Lowlands-Seattle and Vicinity-
Southwest Interior-Tacoma Area.
Red Flag Warning from 11 AM Thursday to 10 PM PDT Friday for
West Slopes of the Central Cascades Generally above 1500
Feet-West Slopes of the North Cascades Generally above 1500
Feet.
Heat Advisory until 8 PM PDT Friday for Olympics.
Excessive Heat Warning until 8 PM PDT Friday for Bremerton and
Vicinity-Everett and Vicinity-Hood Canal Area-Lower
Chehalis Valley Area-Western Skagit County-Western Whatcom
County.
Heat Advisory until 8 PM PDT Thursday for North Coast.
PZ...Small Craft Advisory until 11 AM PDT Thursday for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater 10
To 60 Nm.
&&
$$
www.weather.gov/seattle
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
523 PM MDT Wed Aug 11 2021
.DISCUSSION...(This Evening Through Wednesday)
Issued at 206 PM MDT Wed Aug 11 2021
Upper air analysis shows an upper low over Manitoba, with the
upper ridge over the west coast, and northwest flow aloft over our
region. A weak frontal boundary is expected to move through the
forecast area late tonight. This will lead to slightly cooler
temperatures Thursday and a higher relative humidities. Expect
highs to reach into the upper 70s and low 80s for Thurs/Fri,
before rebounding back to the 90s through the weekend. The added
post frontal moisture and slight increase in instability Thursday
night may be enough to generate an isolated storm or two over the
blackhills region, though overall chances are low, and mostly dry
conditions are expected through Monday. Fires in SE Montana
continue to generate areas of smoke over the forecast area. HRRR
near surface smoke model shows an increase in reduced visibility
this evening as winds transition from westerly to out of the
north.
Over the weekend, the upper ridge slides eastward over the rockies
and eventually the plains region, helping to bring back the
warmer temperatures. We also may see near critical fire conditions
Sun/Mon as RH`s drop into the upper teens, with breezy conditions
possible. Chances for precipitation increase by Tuesday, as the
ridge moves east of the forecast area and southwest flow aloft
develops.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening)
Issued At 522 PM MDT Wed Aug 11 2021
VFR conditions are expected through the TAF forecast period,
although areas of MVFR visibility due to smoke may occur this
evening, especially over northeastern Wyoming and around the
Black Hills area.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Dye
AVIATION...Bunkers
Area Forecast Discussion
National Weather Service Las Vegas NV
755 PM PDT Wed Aug 11 2021
.SYNOPSIS...Northwest Arizona will see scattered afternoon and
evening thunderstorms through Thursday. Elsewhere, storms will be
more isolated over the mountains of southern Nevada and southeast
California. Thunderstorm activity should be minimal Friday through
the weekend followed by increasing monsoonal moisture leading to
an upswing in storms early next week.
&&
.UPDATE...With the setting sun, the limited amount of convection
which did manage to form today is quickly dying, with the only
remaining area of concern across northern Mohave County. A small
cluster of storms which formed near the Mt Trumbull loop continues
to develop southward towards Peach Springs, but is showing signs of
gradual waning as well.
Convective inhibition was too great across most of the lower desert
terrain today to initiate any notable storm activity, which isn`t
too surprising given the scale of the MCS that developed in northern
Arizona last evening. This complex tracked all the way to the
Pacific coast, leaving a broad pool of rain cooled air in it`s wake.
The atmosphere may begin to recover slightly tomorrow, though the
general synoptic flow and magnitude of instability will be quite
similar, with storm chances favored mainly in Mohave County.
Will be making some adjustments mainly to the PoP forecast this
evening to better align with current trends.
-Outler-
.AVIATION...For McCarran...Expect typical south-
southwest winds around 8KT this evening. Quiet weather is expected
with occasional clouds around 15kft through the TAF period.
Thunderstorms are possible Thursday afternoon, but mainly east of
Las Vegas in the Peach Springs corridor.
For the rest of southern Nevada, northwest Arizona and southeast
California...Conditions will be VFR with typical light diurnal
winds. A few thunderstorms may develop, mainly in northwest Arizona,
Thursday afternoon with gusty surface winds and convective
turbulence possible.
&&
.SHORT TERM...through Friday night.
The main area to watch this evening will again be central and
southern Mohave County and the lower Colorado River Valley. Though
the pattern setup is similar to Monday evening, the potential for
organized thunderstorms does not look quite as high. The stalled mid
level circulation over southern Arizona will continue to be a factor
in aiding convection this afternoon, but considerable cloud cover
extending across much of central and southern Mohave County was
limiting surface heating and leading to a later start. Recent runs
of the HRRR indicate thunderstorms developing just east of the
Mohave county border in Coconino and Yavapai counties will work
their way down over Peach Springs toward Kingman and Wikieup late
this afternoon and evening, but may not be able to stay together
west of the Hualapai mountains. Elsewhere over southern Nevada and
southeast California, isolated pulse thunderstorms will be possible
over the mountains this afternoon but should dissipate fairly
quickly in a limited moisture environment as they slowly drift to
the west or northwest off the mountains. Gusty winds will be
possible near any of these storms.
Only very subtle changes in the overall pattern are expected
Thursday with moisture lingering over the same areas. Mohave County
will again see the best potential for scattered afternoon
thunderstorms with a continued tendency to propagate toward the
southwest. Light flow aloft and lingering moisture will remain over
the area Friday and it appears the circulation over southern Arizona
will have moved southward and the limited thunderstorm potential
should be driven by surface heating with isolated storms over the
mountains.
.LONG TERM...Saturday through Wednesday.
While Saturday and Sunday once looked favorable for an upswing in
thunderstorm activity, the latest NBM and model ensembles now
indicate Monday though Wednesday should be the period with
increasing chances for thunderstorms. This is due to a strong area
of high pressure over the northwest states that is forecast to
migrate southward and set up over central Nevada which will shunt
the easterly wave over southern Arizona a little more southward. The
high is then forecast to migrate toward the Four Corners which will
turn the flow more southerly across our region by Monday and the
easterly wave stalls around Yuma then slowly lifts northward and
brings an influx of moisture into our region which begins to
interact with a weak broad trough digging from the Pacific northwest
into northern Californian and Nevada. This pattern would support the
higher chances for thunderstorms indicated by the latest NBM PoP
grids though confidence is fairly low on how the various synoptic
features will come together.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM/LONG TERM...Adair
AVIATION...Outler/Nickerson
For more forecast information...see us on our webpage:
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