Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/26/18
Area Forecast Discussion
National Weather Service Charleston SC
917 PM EDT Sat Aug 25 2018
.SYNOPSIS...
High pressure north of the area will shift over the Atlantic
early next week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
No major changes were made for the late evening update. Did
nudge hourly temperatures down a few degrees per 26/01z
observations. The rest of the forecast is in good shape.
The inland wedge is showing no signs of breaking down and will
remain in tact through the night with a pronounced coastal
trough offshore. Lingering showers the interior will quickly
dissipate as sunset approaches, but guidance suggests isolated-
scattered showers/tstms will redevelop over the Atlantic waters
later tonight as convergence increases along the northwestern
head of the coastal trough off the lower South Carolina coast.
It appears the bulk of this activity will remain offshore, but
will be close enough justify some low-end mentionable pops from
the Beaufort/Hilton Head area into the coastal areas of
Charleston County for much of the overnight period. Inland areas
will remain dry once evening convection diminishes.
Fog and stratus will become a concern inland early Sunday as
skies clear and temperatures drop to cross-over values. RAP and
H3R 1000mb condensation pressure deficits (CPD) drop to less
than 10mb just before sunrise and with the inland wind field
expected to go calm with the decoupling of the boundary layer,
the fog could become locally dense at times. The risk for dense
fog looks to be the greatest from roughly Reidsville northeast
to Allendale and Hampton where CPDs are forecast to be the
lowest, so will hit the fog forecast a bit harder in this area
by introducing an "areas of" qualifier into the gridded and text
forecasts. The Hazardous Weather Outlook will also be updated
to include the potential for a Dense Fog Advisory. Fog is not
expected to be a major issue at the coast.
Lows will range from the upper 60s well inland to the mid-upper
70s at the beaches.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
A weak coastal trough off the coast associated with a
stalled front will dissipate Sunday as surface high pressure
extending from offshore continues. Ridging aloft will remain over
the area through the period. Generally, prospects for convection
through the period are not terribly great, with a diurnal Cu cloud
field each day possibly supporting isolated showers/thunderstorms
where moisture and convergence are greatest, implicating the
seabreeze as the main driver for deeper convection. A weakness in
the ridge with some embedded vorticity enhancement could ripple
around near the forecast area Tuesday, in a Ring of Fire type
scenario. Plenty of variation exists in model prognoses of favored
locations for convection, creating a source of uncertainty in the
forecast. Otherwise, temperatures are expected to be within a degree
or two of normal values.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A deep layered ridge will prevail for much of next week,
minimizing overall convective coverage and maintaining high
temps in the low 90s most areas. The ridge may begin to break
down next Friday or Saturday, allowing for a bit more coverage
of mainly afternoon showers and tstms.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
VFR at the terminals, although fog/stratus is poised to develop
inland. Right now, it appears any fog/stratus will remain west
of the terminals. This will have to be watched carefully through
the night. Isolated/scattered showers/tstms are expected to
develop just off the lower South Carolina coast later tonight.
Most of this activity looks to remain offshore, so no mention
will be included in either the KCHS or KSAV terminals.
Extended Aviation Outlook: VFR conditions are expected to prevail at
both terminals.
&&
.MARINE...
Tonight: The coastal waters will remain situated between inland
high pressure and a stationary front mainly just east of the
area. East winds will shift back to the northeast overnight,
mainly 15 kt or less. Seas will be mainly 3 feet or less,
diminishing to 2 feet or less across the nearshore waters.
Sunday through Tuesday: Expansive high pressure will be the dominant
feature driving local weather, resulting in winds averaging 10-15
knots and seas mainly 1-2 feet, up to 3 feet farther offshore.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
1018 PM CDT Sat Aug 25 2018
...UPDATE TO SYNOPSIS...
.SYNOPSIS...
Issued at 1017 PM CDT Sat Aug 25 2018
WV imagery indicates a weak upper level shortwave trough of low
pressure moving east-northeast across the Western High Plains. Near
the surface, a lee side trough of low pressure is anchored across
eastern Colorado.
&&
.SHORT TERM...(This afternoon through Sunday)
Issued at 1135 AM CDT Sat Aug 25 2018
Passing high clouds over SW KS as of midday, embedded in gentle
SW flow aloft, around a strong upper high centered over East
Texas. Several weak vorticity maxima in this flow will arrive
through this evening, helping to encourage isolated convective
development. 12z NAM develops strong instability by 7 pm, with CAPE
in excess of 3000 J/kg and lifted indices to -8. Models also depict
a significant moisture surge at 850 mb and surface dewpoints, but
also show strong capping at 700 mb (up to 14C). All of this to say,
feel there will be at least isolated convection across the SW zones
by 4 pm, spreading NE this evening, as the latest iterations of the
HRRR suggest. Severe weather is unlikely, but with sufficient
CAPE/moisture, and several active CAM solutions, some stronger
storms can`t be ruled out. A low level jet will establish around
midnight, with 00z NAM increasing 850 mb winds to near 50 kts,
keeping surface winds elevated and the boundary layer well mixed. As
such, temperatures tonight will remain warm and elevated, struggling
to fall below 70 degrees through Sunday morning (upper 60s west,
lower 70s east).
Sunday...Hot and windy. Perhaps some convective remnants/debris
across the NE zones early as NAM depicts, otherwise pressure
gradients will tighten sharply south of a surface low in western
South Dakota. 12z GFS/MAV guidance is notably stronger (up to
28 mph sustained) versus 12z NAM/MET, and opted for the stronger
solution for the wind grids. A typical Kansas windy day, with
gusts of 38-40 mph expected. The strong downslope component along
with 850 mb temperatures in the upper 20s C will send temperatures
soaring into the upper 90s, with a few locales near the Oklahoma
border eclipsing 100 degrees. Summer is still alive and well.
.LONG TERM...(Sunday night through Saturday)
Issued at 145 PM CDT Sat Aug 25 2018
Dry weather will prevail through the long term, with little
opportunity for rainfall. As such, the forecast will focus on a
cold frontal passage, and resultant wind shifts and temperature
flucuations.
Monday appears quite hot, and will be the hottest day of the week.
SWly downslope winds along with prefrontal compression, along with
850 mb temperatures spiking to near 30 C, will send afternoon
temperatures soaring toward 100 degrees. Most locations will
achieve highs in the 97-99 range, with 100-103 expected along the
Oklahoma border. SW winds will be strongest across the SE zones,
where gusts of 30-40 mph are expected.
Model consensus including the 12z ECMWF show the dry cold front
entering the NW zones around sunrise Tuesday. Winds will veer
northerly and increase through midday, with gusts over 30 mph.
Cool advection will knock about 10 C off 850 mb temperatures,
allowing for milder afternoon temperatures in the 80s. Frontal
and parent wave timing/position is not expected to be favorable
for showers and thunderstorms in SW KS. The only zones with a
chance will be the far SE (Barber county) which will be nearest
the front at peak heating Tuesday afternoon/evening. Any activity
in these region would be isolated at best, with the majority of
convection favoring NE Kansas.
Models do hint at some elevated convection potential north of the
frontal boundary Tuesday night/Wednesday morning, with 12z ECMWF
favoring southern zones for this activity. Low pops from the model
blend were retained. Afternoon temperatures will remain in the 80s
on Wednesday, as the frontal boundary resides south of SW KS. The
front will return north as a warm front Wednesday night/early
Thursday, and will likely initiate at least isolated convection as
it does. Much hotter afternoon temperatures will follow on
Thursday, but especially Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 626 PM CDT Sat Aug 25 2018
Isolated to widely scattered thunderstorms will be possible early
this evening north of a warm front and ahead of an upper level
disturbance that will be crossing southwest Kansas between 00z and
06z Sunday. Based on the latest radar trends and the widely scattered
nature of these storms am leaning towards not mentioning thunder
in the 00z TAFS for DDC. For GCK and LBL will mention a period of
VCTS between 00z and 03z Sunday. HYS may also have an slim
opportunity for convection, small as it may be, between 03z and
06z. Gusty southeast winds will subside by sunset but continue at
10 to 15 knots. The southeasterly winds will become more southerly
overnight as the warm front lifts north across western Kansas.
BUFR soundings indicating should we have ceilings early tonight
the bases will be in mainly the 5000 to 9000 ft AGL level.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 71 98 73 99 / 10 10 10 0
GCK 69 96 69 98 / 40 10 10 0
EHA 69 97 68 99 / 60 10 10 0
LBL 72 99 71 102 / 20 10 10 0
HYS 71 96 72 97 / 30 20 10 0
P28 73 97 75 98 / 10 10 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJohnson
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Burgert
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
248 PM PDT Sat Aug 25 2018
.SYNOPSIS...Near seasonable temperatures are expected to continue
through next week as a series of upper-level disturbances impact
the West Coast. Additionally, smoke and haze will linger across
most of the area through the rest of the weekend.
&&
.DISCUSSION...Upper-level troughiness is expected to continue
through early next week, with another upper-level disturbance
forecast to dig across the Pacific Northwest and northern
California late in the week. These features will aid in keeping
temperatures near normal across northwestern California through
next week. In addition, a slight chance of rain will accompany the
late week trough, but confidence is low in that scenario.
Meanwhile, Saturday afternoon visible satellite imagery shows
marine stratus has dissipated over most of the coastal waters.
The lone exceptions are portions of Humboldt and Del Norte
counties, and south of Cape Mendocino, which continue to see
stratus offshore and along the immediate coast. In general,
filtered sunshine from smoke aloft and locally hazy conditions are
expected across much of the region through at least tomorrow.
This is supported by recent HRRR guidance, which depicts interior
areas of smoke remaining stationary, and smoke from fires in
Oregon drifting south across the coast through the weekend.
&&
.AVIATION...Conditions observed yesterday are occurring again
today, with stratus clearing the coast earlier this morning.
Smoke from the fires in SW Oregon continues to drift south across
Del Norte county. This may lead to some lower visibilities and or
opaque smoke layers. However overall impacts are expected to be
low. Across the rest of the interior smoke continues to stick
around however only minimal impacts have been reported. Otherwise
VFR conditions will prevail through this evening. Tonight coastal
stratus will redevelop along the Humboldt coastline leading to
MVFR to IFR ceilings with reduced visibilities. Del Norte is
expected to have elevated offshore flow which may limit stratus
redevelopment. /WCI
&&
.MARINE...A Small Craft Advisory over the outer coastal waters for
north winds from 20-30 kt and 8 to 10 foot seas remains in effect
through Monday evening. Meanwhile, a small craft advisory for
steep seas will expire over the inner waters this evening.
However, gusts from 20-30 kt will be possible near Point Saint
George and Cape Mendocino through Sunday night. Marginal low end
gale force gusts will be possible over the outer waters during the
next day or two, but the areal extent is expected to be too small
for a gale warning at this time. Otherwise, a small west-northwest
swell near 10 seconds will persist through much of the forecast
period. Another northwest swell train is forecast to arrive by
the middle of the coming week. /SEC/JMG
&&
.FIRE WEATHER...Locally gusty northeast winds will be possible
tonight and Sunday night across the ridge tops of interior Del
Norte county as a weak upper-level trough moves out of the western
U.S. RH recoveries have been pretty good the past few days and
this trend is expected to continue through early next week.
Otherwise, onshore flow will yield near normal temperatures area-
wide through next week.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until
3 AM PDT Sunday for PZZ450.
Small Craft Advisory until 9 PM PDT Monday for PZZ470-475.
Small Craft Advisory until 6 PM PDT this evening for PZZ455.
&&
$$
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Area Forecast Discussion
National Weather Service Glasgow MT
857 PM MDT Sat Aug 25 2018
.DISCUSSION...
HRRR Smoke model surface visiblity has done a decent job with the
smoke forecasts the last few days. It`s showing things moving
southward out of our CWA for a few hours tonight before returning
again tomorrow with the SE flow ahead of the cold front coming
through. So, have added haze at this time (I wish we could just
call smoke smoke, but visibility restrictions give firm
definitions in our forecast grids) because I`m a bit uncertain
how dense the smoke will be at the surface when there is also rain
happening.
When it comes to the fine details of the rain event coming into
the area there is some big differences. When you look at the big
picture, a 30-40 mile difference isn`t a big deal but in a drought
stricken region some people will be seeing moisture by noon and
others won`t. Most models were keeping things mostly in the
northern portion of our CWA with areas south of Fort Peck lake
having better chances of moisture on Monday. So, if you don`t see
it on Sunday there`s still a shot on Monday!
fransen
The deep upper level trough digs into the region on Monday. This
system will bring better chances for showers and thunderstorms
through Monday night. After the passage of this feature, a cooler
air mass is forecast to encompass the region.
For mid next week, a more seasonable weather pattern is expected
with high in the mid to upper 80s and lows in the mid 50s. FGC
&&
.AVIATION...
FLIGHT CAT: mostly VFR tonight with periods of MVFR conditions
possible on Sunday.
DISCUSSION: Smoke continues across the area,reducing the
visibilities between 7 to 9 miles from time to time. No
improvement in these conditions are expected as latest visible
images depicted smoke moving from west to east across the area.
However, P6SM visibilities should prevail through the forecast
period.
An increase in cloudiness with showers are expected late tonight
into Sunday morning with occasional MVFR conditions.
WIND: Light and variable the rest of this afternoon and turning
east at 5 to 10 knots tonight.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Hastings NE
627 PM CDT Sat Aug 25 2018
.SHORT TERM...(This evening through Sunday)
Issued at 237 PM CDT Sat Aug 25 2018
Aloft: Animations of RAP dynamic tropopause...12Z RAOBs and
aircraft data showed a large subtropical high over TX. A large
trof encompassed Cntrl/SW Canada back into the Pac NW...with svrl
embedded shortwave trofs. The ridge axis associated with the ST
high moved E of the rgn this AM. So thru 00Z/Mon...SW flow will
prevail over the Cntrl Plns as svrl shortwave trofs deepen the
mean trof over the Pac NW/Nrn Rckys. WV imagery showed a
disturbance near the AZ/NM border. It will skirt the NW periphery
of the ST high and cross Neb/KS tomorrow.
Surface: Weak high pres was near MSP while a Canadian cool front
extended from low pres near Lk Winnipeg across the Dakota`s into
WY. The high will merge with a larger high over the Ern USA
tonight. The front will become stationary along the SD-Neb border
with cyclogenesis occurring over SD tomorrow. This will keep the
CWA in the warm sector thru tomorrow.
Rest of this afternoon: Gradually increasing mid-high clds. Hot
as temps will peak in the low-mid 90s. Humid SE of HSI. Could see
the Heat Index touch 100F at HJH.
Tonight: There will be quite a bit of tstm development this
afternoon well to the SW with the trof over the Desert SW heading
this way. That will maintain incrsg clds and skies will become
m/cldy. It should also maintain some of these sct shwrs/tstms thru
the night. They should cross the CWA from SW-NE mainly after
midnight.
Because of the sct nature (i.e. some areas will remain dry) kept
POPs low. But where it does rain...POPs will be too low. Mdl
consensus has the "best" chance S and E of the Tri-Cities.
MUCAPE will be sufficient for strong updrafts (1000-1500 J/kg)
...but weak effective shear will offset as the wind profile
becomes unidirectional in the cloud-bearing layer.
It will be a warm/muggy night.
Sun: Starts m/cldy with sct shwrs and a few tstms...primarily E
of Hwy 281. Should be E of the CWA by midday. Decreasing clds from
SW-NE as the trof departs. Breezy S winds will gust 25-30 kt...
espcly E of Hwy 183.
Can`t rule out an isolated tstm or two redeveloping after 4 PM...
S of a line from MCK-EAR-OLU. It is entirely possible nothing
happens due to lack of help aloft and most likely there will be
subsidence in the wake of the trof. "If" something goes...it could
be svr with MLCAPE 1500-2500 J/kg and 0-6 km shear around 25 kt.
SPC currently has no risk of svr tstms...but that is most likely
due to very low prob of anything occurring at all.
Another hot day with widespread 90s. The one exception could be N
and E of GRI...where lingering clds could keep temps from reach
90F.
.LONG TERM...(Sunday night through Saturday)
Issued at 237 PM CDT Sat Aug 25 2018
Aloft: Looking at spaghetti plots of the last 2 runs of the
EC/GFS/GEM/UKMET...the longwave pattern that develops this wknd
will be with us thru next wknd. A strong ST high will be parked
between AK and HI. The Nrn Rckys trof will head E...crossing the
Nrn/Cntrl Plns Tue. Heights will then rise over the Plns Wed with
the trof reforming over the Pac NW/Nrn Rckys Thu-Fri. Confidence
is high thru Thu given tight mdl clustering...but substantial
spread dvlps Fri- Sat with how deep the Wrn trof is fcst. The 12Z
GFS which keeps the trof progressive is an outlier against its own
ensemble mean. The 06Z run looks like the other mdls with
potential for a closed low (possibly a cut-off?) to form. Lots of
spread on when and where. Overall this pattern means the flow will
be WSW or SW over the Cntrl Plns.
Surface: Due to the SW flow aloft...the cool front fcst to be
stalled along the SD-Neb border will take its sweet time dropping
thru the CWA. FROPA is currently fcst 12A-12P Tue. High pres will
cross the CWA Wed. Then it`s back to the warm sector of low pres
that will be over Cntrl Canada Thu-Fri. Uncertainty then develops
regarding when the next cool front will move thru.
Temps: Hot again Mon but it will be the last day in this string
of very warm/hot days. A refreshing break from the heat Tue-Wed
with highs in the 70s to low 80s. Then back to at least normal
(80s-low 90s) Thu-Fri and possibly Sat.
Rain: Not looking good. Next wk looks mainly dry. Thu night and
Fri night currently hold some promise potential for sct tstms
associated with the low-lvl jet...but not everyone will see rain.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 625 PM CDT Sat Aug 25 2018
Clouds will be moving into the terminals during the night. Expect
there to be VFR conditions. There could be isolated showers and
thunderstorms but the chance is low enough at this time that will
leave them out.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...JCB
Area Forecast Discussion
National Weather Service Goodland KS
945 PM MDT Sat Aug 25 2018
.SHORT TERM...(This evening through Tuesday)
Issued at 315 PM MDT Sat Aug 25 2018
Forecast concerns will be chance of thunderstorms into Sunday, how
hot does it get through Monday, Fire Weather on Monday, and how much
does it cool off Tuesday. Satellite showing an amplified flow over
the Pacific. This flow flattens out and is more progressive over the
country. Subtropical moisture is streaming into the area from the
southwest.
For Tonight/Sunday...Very unorganized/weak forcing expected through
the night. Currently earlier storms have weakened and moved north of
the area. These storms appear to be result of right rear quadrant of
jet. Expect that activity to move north as that right rear quadrant
moves north and then stays to the north and west of the area through
the night. Little to no height falls also do not occur through the
night with the largest happening late in the night.
Still despite the loss of the jet, the main shortwave and height
falls are near/over northwest corner with also a subtle surface
convergence boundary. Earlier models were not developing much
precipitation in the northwest portion. However they now appear
to be missing this with the 18Z Nam and the most recent run of the
Hrrr catching the persistent linear storms near/over Yuma county.
So raised pops in the northwest corner.
A second area of development looks to be in the southern third of
the area. This is where the best mid level moisture resides plus
this is where the least cap and most instability resides. So will
also have chance pops in this area as well. With precipitable
water values near 1.5 inches, locally heavy rainfall will be
possible and Cams would support that as well. In addition to the
locally heavy rainfall, damaging winds will be the other main
threat due to steep low level lapse rates/high Dcape values.
For Sunday, right rear quadrant stays near the northwest portion
of the area through the afternoon. Also it looks like shortwave
ridging will be in place during the day. So will keep the day dry.
Models have not been too bad on maxes recently and see no reason
to deviate significantly from any blend. That means temperatures
in the 90s once again.
For Sunday night/Monday...Right rear quadrant of jet is near the
northern portion of the area through the evening. This moves
across the forecast area during the overnight hours. Next
shortwave trough moves through during the evening. Right now the
blend only gives me a slight chance in the evening. Can see this
activity needing to be extended into the overnight hours. At this
time, I can live with what is in there.
Main change for this period was to make the high temperatures
warmer. On Monday, look to have plenty of sun with downslope
winds through mid levels. Also should have prefrontal warming. So
warmed maxes above what the blend gave me. For the fire weather
concern please refer to that section below.
For Monday night/Tuesday...Front moves through during the night.
However it looks dry due to deep dry air mass with 700 mb
temperatures of +15 or higher. So we stay capped. Models are cooler
on Tuesday from previous run. Blend does look reasonable at this
time, and see no reason to change it.
.LONG TERM...(Tuesday night through Saturday)
Issued at 131 PM MDT Sat Aug 25 2018
After the cold front passes through Tuesday, a warm front moves
through the Tri-State region Wednesday into Thursday raising temperatures
back into the 90s through the end of the week. High pressure
rebuilds over the southwest U.S. from the East coast by Thursday.
A series of shortwaves will move through the Tri-State region
Wednesday night through Saturday leading to precipitation chances,
though chances remain low at this time. Temperatures cool off
slightly Saturday as a trough extends south across the central
Plains and moves eastward during the day. By Saturday night, a
ridge begins shifting east over the southern Plains.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 945 PM MDT Sat Aug 25 2018
KGLD, vfr conditions through the period. A south wind around 10kts
is expected at taf issuance which will continue through sunrise
Sunday morning before veering to the southwest at similar speeds
around 14z. After 00z winds expected to back to the south near
10kts.
KMCK, vfr conditions expected after 07z. For the first hour of the
taf period there is a possibility of showers and thunderstorms
moving through which could produce sub vfr visibilities in
moderate to heavy rain. Gusty and erratic outflow winds also
possible. Otherwise after about 07z winds generally from the
southeast to south at speeds under 10kts.
&&
.FIRE WEATHER...
Issued at 315 PM MDT Sat Aug 25 2018
For Monday...For counties along the Colorado border, relative
humidities will drop to near 15 percent. However, at this time winds
look to stay below 25 mph. Will continue to watch this day closely.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...NEWMAN
AVIATION...99
FIRE WEATHER...BULLER
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
806 PM EDT Sat Aug 25 2018
.UPDATE...
Issued at 757 PM EDT SAT AUG 25 2018
Some mid and high level clouds continue to move southeast across
the region this evening. Convection upstream over southeast IN and
southwest OH continues to approach northern KY. This convection
should diminish over the next couple of hours and should not make
it into the area as sunset is quickly approaching. Otherwise,
overnight low should be seasonably mild with valley fog forming a
little after midnight near the larger creeks, lakes, and rivers.
Hourly grids were updated to account for recent observation and
satellite trends. This, however, led to no substantial changes at
this time.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 427 PM EDT SAT AUG 25 2018
Current surface analysis shows high pressure to the east of
Kentucky. An upper level shortwave trough is exiting the Ohio
Valley today and ridging will build in overnight and into Sunday
afternoon. This will lead to warmer conditions for the weekend and
into the start of the work week. Due to return flow, there is
warm, moist air available to help bring the possibility of showers
and storms through the weekend, mainly during the afternoon and
evening hours. Current radar trends show some shower activity in
the northern portion of the Bluegrass, but is expected to diminish
this evening with the sunset as reflected by the HRRR and the
NAM. Chances of showers and storms are possible again tomorrow
afternoon/evening with this pattern as well, with the best chances
north of the Mountain Parkway and to the far east. Another area
of concern for the short term will be fog, but it should mainly be
concentrated in the river valleys Sunday and Monday mornings.
Utilized the CONSShort for PoPs for the majority of the period.
Did opt for the Superblend for Sunday afternoon, which looks to
favor the ECMWF solution as opposed to the GFS or NAM. Followed
the lead of GFS/NAM Guidance and the CONSShort with respect to
temperatures for the short term. However, included a ridge/valley
temperature difference Sunday and Monday mornings due to clearing
skies and southerly flow. High temperatures Sunday afternoon will
be in the mid to upper 80s. Lows Sunday and Monday mornings will
range from low 60s in the valleys to upper 60s on the ridgetops,
with some areas seeing around 70 degrees Monday morning.
.LONG TERM...(Monday through Saturday)
Issued at 513 PM EDT SAT AUG 25 2018
The work week is expected to start off with a dirty upper level
ridge over the Mid Atlantic and southeast CONUS. Surface high
pressure centered to our southeast will allow for a continued weak
flow of warm and humid air into the region. Diurnal
destabilization coupled with weak ripples in the upper level flow
may be enough to get poorly organized thunderstorms bubbling on
Monday and Tuesday.
The upper level ridge is expected to weaken and get suppressed to
the south at mid week, as a large portion of the current northwest
CONUS trough migrates eastward through the flow across the
continent. This will support a surface cold front to move
southeast across the Midwest early in the workweek, reaching the
Ohio Valley Wednesday. At this point there are some minor
differences between the GFS and ECMWF, but it just happens to be
over our area. The GFS is a bit strong with the passing upper
level trough and allows the front to drop to near the TN border
before it stalls and washes out, while the ECMWF is weaker and
appears to hold it closer to the Ohio River. It`s too early to say
exactly where it will stall, but probably somewhere in our area.
Our best chance at rain will come during this time. However, the
best upper level support remains to our north with the passing
upper trough, and at this point our POPs are held no higher than
chance category in any given period.
By the weekend, the upper level ridge is expected to begin build
over the southeast CONUS again. This would send whatever is left
of the fading front northward, and plant us back more solidly in
the warm and humid air, with a continuing small potential for
deep convection.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 806 PM EDT SAT AUG 25 2018
Upper level ridging will build into the area through the period.
Convection upstream of the region should dissipate over the next
couple of hours with only some debris clouds passing over the
northern counties. The main concern for the overnight will be
valley fog that could affect a couple of the TAF sites. At this
time, have kept the previous forecast of MVFR conditions for SME
and LOZ due to their proximity to valleys, and for SYM due to
clearing skies and sufficient moisture from southerly flow and
the proximity to Cave Run Lake. Some non TAF sites could
experience IFR fog between 6Z and 13Z. All the fog should
dissipate by around 13Z. Winds will generally be light and out of
the south/southwest, but toward 16Z, winds should increase to between
5 and 10 KT for more western and northern locations.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...CGAL
LONG TERM...HAL
AVIATION...JP
Area Forecast Discussion
National Weather Service Elko NV
204 PM PDT Sat Aug 25 2018
.SYNOPSIS...A cold front brings gusty winds to northern and
central Nevada on Sunday afternoon. Cooler weather is expected
with local frost possible Tuesday morning for the northern
Nevada valleys. High pressure returns by Wednesday with seasonably
warm daytime weather but cool nights.
&&
.SHORT TERM...Tonight through Monday.
The HRRR smoke model continues to show waves of smoke moving
across northern Nevada this afternoon and tonight. At least for
the next couple of days, do not think we will see any improvement.
Digging energy on the backside of Pacific Northwest trough will
drive a cold front into northern Nevada by Sunday night. A thin
ribbon of moisture is associated with upstream energy, but not
much dynamical lift to squeeze out any moisture. Breezy
conditions will develop ahead of the front with gusts in the
30-35 mph range. Front pushes southward toward southern Nevada
Sunday night, resulting in cooler weather for Monday with highs in
the 70s toward the northern border but rising to the mid to upper
80s across northern Nye county.
.LONG TERM...Monday night through next Saturday.
The far northern valleys such as Wildhorse could drop below
freezing Tuesday morning. With plenty of sunshine, afternoon highs
will be near the norm for late August. Subtropical high core
expands over the desert southwest on Wednesday and Thursday, but
without the July intensity. Daytime temperatures rebound but 80s
will be the general rule with cool nights. The next trough
clipping Nevada will be Friday with limited moisture, but an
isolated shower/storm is not out of the question over the Jarbidge
wilderness. Models show some spread later this week resulting in
low confidence on any rainfall chances. Afternoon temps stay
seasonably warm, but not hot.
&&
.AVIATION...Local wind gusts to 25 knots will possible through
early evening. Gusty winds will be higher Sunday afternoon,
reaching 30-35 kts. Visibility dropping as low as 5SM in haze will
be possible at KWMC, KBAM, and KEKO.
&&
.FIRE WEATHER...With high confidence, the watch has been upgraded
to a Red Flag warning for winds and low humidity. Widespread wind
gusts of 30-35 mph are expected Sunday afternoon. Gusty winds
will be less prominent across fire zone 457, but think that gusty
winds will exceed the red flag wind threshold as front is expected
to push over central Nevada.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 11 PM PDT Sunday for Central
Lander and Eureka Counties-Central and Western Humboldt County-
Eastern Elko County-Eastern Humboldt County and Northwestern
Elko County-Northern Nye County/Lander and Eureka Counties South
of Highway 50-Southwestern and Central Elko County-White Pine
County.
&&
$$
88/88/88/88
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
840 PM CDT Sat Aug 25 2018
.UPDATE...
840 PM CDT
The conditional severe threat has ended in the CWA, with isolated
storms having struggled to reach sustained levels. A few showers
and possibly a storm or two will continue east of I-55 through 11
pm or so.
Otherwise attention is on fog overnight into early Sunday morning
with a moist low-level air mass in place. Dew points are in the
70s across much of the area, with temperature-dew point spreads of
only a few degrees at several places and already some haze. Often
with these very moist air masses during summer it is mainly a
haze, except for favored low-lying locations and near river
valleys that see the true dense fog. Nights are a bit longer
though and winds are calm in many locations, so the setup may be a
little better. High-resolution guidance favors along/north of
I-80 more so for potential dense fog, but there has been a lot of
variability in solutions (such as the HRRR this evening). Have
generally continued forecast as is.
Looking at Sunday forecast heat index readings, there is potential
to be a tad higher in some spots, possibly closing in on 105,
given isolated upper 70s dew points were seen today and could
materialize again Sunday. We should be mainly cloud free, so
going highs of 90-93 in most areas look good.
MTF
&&
.SHORT TERM...
300 PM CDT
Through Tonight...
No big changes in thinking from previous AFD update. Continue to
have concern for a conditional severe risk mid afternoon into this
evening. Lack of synoptic forcing with h5 height rises continues
to call into question convective coverage. However, lower level
convergence could be aided by differential heating boundaries left
over from eroding stratus. In addition, mesoanalysis does show a
weak h7 trough that will remain over the area into early evening
and short range guidance indicates weak 700 mb PVA spreading
across area.
It`s tough to say for sure, but latest W/V imagery may show a
weak wave approaching from IA related to aforementioned 700 mb
PVA. With better insolation now occurring and advection of steeper
lapse rates, 70s dew points (76 at VYS and 79 at PNT) and temps
into 80s over IL has yield large instability already up to
2500-3500 j/kg of MLCAPE, which should further increase a bit over
next few hours with continued heating. With convective temp on
12z RAOBs in upper 80s to around 90, despite mesoanalysis showing
no CINH, there`s probably some minimal capping, so we`ll be
needing the weak forcing and any boundary convergence for CI.
There`s currently a few areas of slightly enhanced Cu south of
I-88 in IL and will need to watch satellite trends closely for
further agitation of Cu field over next few hours.
There is a decent signal on CAMs for CI occurring sometime in 21
to 00z timeframe, however still too early to call where it will
occur at this time and TSRA coverage will likely remain low for
reasons above. Based off latest trends, have focused somewhat broad
brushed low-mid chance PoPs up to I-88 or so southward to IL and
Kankakee river valleys, though in reality actual area affected
will likely be smaller than this. Regarding the severe risk,
conditionally speaking, the environmental parameters look that
they will be favorable for isolated supercells given 30-40 kt of
effective bulk shear and good turning of winds from south-
southwest at surface to southwest at 850 mb (~25 kt) to northwest
at 500 mb. In presence of large CAPE, including in 0-3 km layer,
have concern that any thunderstorm that can take advantage of this
environment could get quite intense and capable of localized more
noteworthy severe.
SPC maintained the marginal risk south of I-88 and remain
in general agreement with this, though again the actual hazards
from intense storms could be higher end than would normally be in
a level 1 risk. With relatively weak southerly surface flow, still
think main threat from any isolated severe storm would be large to
very large hail and downburst winds. However, the very rich
boundary layer moisture will certainly yield very low LCL heights
and there will be high 0-3 km instability as mentioned. Both of
these could overcome weak sfc flow with otherwise decent low level
shear for a very isolated tornado risk. SPC still did not include
marginal/2% tor probs in updated 20z outlook, but this will be
something to watch. Finally, locally torrential rain will be
likely in any intense t-storms with very moist air mass and thus
could also yield a localized flash flooding risk. The strong-
severe t-storm and flooding risk should shift east with time and
end by mid evening or so.
Shifting gears to the overnight into Sunday morning, winds will
drop to light/variable to calm overnight and very moist air mass
will remain in place. This will likely set the stage for fog
development, some of which could become dense, especially outside
of Chicago. Some of the guidance is hitting the fog pretty hard,
so wouldn`t be surprised if portions of area need a dense fog
advisory. Added patchy to areas of fog mention in grids, though
for now precluded any mention of dense fog. It will be a warm,
muggy night with lows in the mid 60s to lower 70s.
Castro
&&
.LONG TERM...
311 PM CDT
Sunday through Saturday...
The warming trend with humid conditions and periodic chances for
thunderstorms should persist through the middle of next week.
Sunday through Tuesday should be the warmest days of the long range
forecast period with max temperatures in the upper 80s to low 90s
and dewpoints in the middle 70s. Heat Index values should reach or
slightly exceed 100 F during this period. There should also be
periodic chances for thunderstorms as a series of shortwaves ride
over the apex of the upper ridging. Much of the day on Sunday will
be dry, but anticipate thunderstorm chances to increase in the
afternoon and evening. At this time, these increased chances will be
for primarily the northern half of the CWA. Some of the high res
guidance is suggesting the possibility of thunderstorms developing
over Iowa and then and then develop upscale to a bowing line which
could impact at least the northern portions of the CWA, posing a
threat for strong, damaging wind gusts for the afternoon and into
the evening hours. The warm/humid conditions will likely persist
through the day on Tuesday. The longer range guidance remains
relatively consistent on a cold front pushing through the area
Tuesday night, ushering in cooler air, with max temps dropping back
into the 70s for Wednesday and Thursday. There may be some lingering
showers or thunderstorms over the far eastern portions of the CWA
Wednesday morning, but dry conditions are expected for the remainder
of Wednesday and through Thursday night.
&&
.AVIATION...
For the 00Z TAFs...
634 pm...Forecast concerns include isolated thunderstorms south
of terminals this evening...fog overnight/Sunday morning and a
chance of thunderstorms Sunday evening.
Isolated showers have festered along a c75/ikk/vpz line late this
afternoon and this is the favored corridor for any additional
activity including isolated thunderstorms this evening. Thus will
remove vcts mention at mdw/gyy. Confidence for thunderstorms late
Sunday afternoon into Sunday night is low and have stayed dry with
this forecast. There is some potential for isolated activity near
the terminals late Sunday afternoon and then a more broken line of
thunderstorms from eastern IA/northwest IL into southern WI later
Sunday evening. There remains too much uncertainty both for timing
and for coverage to include any mention at this time with better
chances north of the terminals.
There is already a light haze late this afternoon and guidance is
suggesting widespread fog tonight...especially north of I-80.
Current tafs have fog handled well but its possible prevailing vis
ends up lower in some locations. Added a tempo for 1/2sm at dpa
and its possible some areas will have dense fog. With the very
moist low levels...vis improvement Sunday morning will likely be
slow with mvfr vis through early afternoon possible in some areas.
Light southwesterly winds will become light southerly or light
southeasterly this evening then calm/variable overnight. Winds
will return to southwesterly late Sunday morning with speeds
increasing to 10-12kts Sunday afternoon. Forecast soundings
suggest southwesterly winds may increase further Sunday evening
with some gusts developing. cms
&&
.MARINE...
311 PM CDT
A series of weak lows will track across the Upper Great Lakes region
over the next couple days, keeping generally southerly to south-
southwesterly winds across the lake through Tuesday. Speeds will be
relatively light through Sunday, but the pressure gradient across
the lake will strengthen Monday and Tuesday with speeds up to 25 to
30 kt. A cold front is expected to push across the lake Tuesday
night with winds shifting through westerly to northwesterly by
Wednesday morning. Brisk northwest winds will set up for a short
time Wednesday and then diminish again Thursday as high pressure
builds across the lakes behind the exiting cold front.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Newport/Morehead City NC
920 PM EDT Sat Aug 25 2018
.SYNOPSIS...
A coastal trough will remain near or just offshore into Monday.
An offshore high and inland trough pattern will return through
the middle of next week. A cold front will approach from the north
Thursday into Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 920 PM Saturday...The isolated showers have persisted
despite the loss of heating. The HRRR model seems to have a good
handle on this and dissipates them around midnight, so will
extend mention in the forecast through the evening hours. High
pressure will continue to build over the area from the north
overnight producing mostly clear skies and light winds.
Resulting radiational cooling will lead to the development of
patchy fog and low clouds after midnight. Overnight lows will
range from the low to mid 60s inland to the low 70s beaches.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
As of 3 PM Saturday...With surface high pressure re-establishing
itself along the Delmarva region and ridging south into the
Coastal Carolinas on Sunday, expect a decent amount of
subsidence to develop across our region and will go with a dry
forecast for Sunday. Temperatures should respond with highs
Sunday warming to the mid/upper 80s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
As of 300 AM Sat...Seasonable weather to start next week will
give way to warmer and more humid conditions by mid week with
highs temps returning to the low 90s. A mostly dry pattern is
expected with high pressure influencing the region, however a
cold front will approach from the north by late week, and bring
a bit more unsettled conditions to Eastern NC.
Sunday...Another beautiful late August day is expected Sunday,
with "low" humidity and highs in the mid to upper 80s. High
pressure will be located both well offshore and over the
southern Appalachians, with a weak trough in the middle just
off the coast. There will be showers associated with this
boundary, and most of the activity should remain offshore.
However, will keep a slight chance PoP along the immediate coast
for the morning hours, and then expand the area a bit inland in
the afternoon, with an isolated sea breeze shower or
thunderstorm possible. Low temps overnight Sunday will be near
normal, with lows ranging from the upper 60s inland to the low
70s near the coast.
Monday through Wednesday...Broad area of high pressure will
strengthen over the western Atlantic and stretch westward to
the southeast US early next week. As winds become
south/southwest, humidity will increase, as well as high
temperatures. Highs will climb into the low 90s inland, and mid
to upper 80s near the coast during this period. The increased
heat and humidity will also produce some hazardous heat indices
ranging from 100-105 during the mid to late afternoons. Mostly
dry conditions are expected, with the exception of Wednesday
afternoon, when some sea breeze showers and thunderstorms are
possible. Will keep a slight chance PoP for the area generally
south of US 264. Low temps will be milder, ranging from the low
70s inland, to the mid to upper 70s near the coast.
Thursday and Friday...High pressure will retreat slightly
offshore, as a broad upper level trough pushes east across the
northern Mid-Atlantic states. As the associated cold front
approaches scattered showers and storms will break out ahead of
it, as well as along the front. There remains some sizable
timing differences between the models, so have chance PoPs in
the forecast for the better part of this period. High temps will
likely be in the upper 80s to low 90s Thursday, and slightly
cooler on Friday. Low temps will again be mild, ranging from
the low to upper 70s across the region.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Short Term /through Sunday/...
As of 655 PM Saturday...High pressure will prevail over Eastern
NC through the weekend producing clear skies, light winds and
mostly VFR conditions. Radiational cooling late tonight will
result in the development of IFR conditions in patchy fog and
low clouds which will dissipate early Sunday morning.
Long Term /Sunday Night through Thu/...
As of 320 AM Sat...VFR conditions are expected through the long
term with high pressure offshore. There will be a very small
chance for rain both Sunday Night and Wednesday, but this
shouldn`t cause any issues at the terminals.
&&
.MARINE...
Short Term /Tonight and Sunday/...
As of 920 PM Saturday...Light NE-N winds, mainly 10 kt or less
will become SE-S Sunday as high pressure remains over the
waters. Seas 3 to 4 ft this evening will subside to around 2
feet Sunday.
Long Term /Sunday Night through Thursday/...
As of 320 AM Sat...Winds will be turning to the south 5-10 kts
Sunday night. Winds will then be mostly SW/SSW 5-10 kts through
Wednesday, with some diurnal increases to 10-15 kts during the
afternoons. Seas will be mostly 1-2 ft Sunday Night though
Tuesday, and then increase slightly to 2-3 ft Tuesday and
Wednesday.
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...JME/CTC
NEAR TERM...CTC
SHORT TERM...JME/CTC
LONG TERM...SGK
AVIATION...JME/SGK/MS
MARINE...JME/CTC/SGK
Area Forecast Discussion
National Weather Service San Francisco Bay Area
852 PM PDT Sat Aug 25 2018
.SYNOPSIS...A persistent trough of low pressure near the West
Coast will maintain a deep marine layer and slightly cooler than
normal temperatures through the weekend and well into next week.
&&
.DISCUSSION...As of 8:50 PM PDT Saturday...A slight reduction in
the depth of the marine layer since yesterday resulted in
slightly warmer temperatures today across the North and East Bay.
However, persistent low clouds near the ocean meant slight
cooling for most coastal locations. But temperatures regionwide
remained slightly cooler than seasonal averages, as has been the
case for the past several days. Hazy conditions persisted across
the region today due to smoke drift. However, smoke concentrations
were generally lower today compared to two days ago. HRRR smoke
model output indicates continued improvement in air quality
through Sunday except for the North Bay.
Latest models maintain a weak upper trough along the West Coast
through at least the middle of next week. This will result in
continued cooler than normal temperatures as well as a relatively
deep and persistent marine layer. Model temperature guidance
indicates little change on Sunday, followed by slight cooling
inland during the early part of the work week as a weak upper low
develops near the northern California coast. The GFS then
indicates warming late next week, especially inland, as an upper
ridge over the Desert Southwest builds westward across northern
and central California. However, the ECMWF maintains a weak trough
over California through the end of the week and therefore does not
show much in the way of late week warming like the GFS.
&&
.AVIATION...as of 4:31 PM PDT Saturday...for 00Z TAFs. Moderate
marine layer and onshore wind will usher low clouds and patchy fog
inland overnight. Expect clearing by late morning or early afternoon
again on Sunday. Hazy conditions lingering with reduced slant wise
visibilities mainly away from the bays and well inland.
Vicinity of KSFO...VFR, afternoon and evening west winds 15-20 knots.
MVFR cig 07z-18z.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Early stratus return 01z-03z, cigs transitioning
to IFR/LIFR tonight. IFR/LIFR Sunday morning, VFR returning Sunday
afternoon.
&&
.MARINE...as of 4:25 PM PDT Saturday...A 1036 mb high is centered
1100 miles west of Cape Blanco. A thermal trough is over the
interior. Northwest winds will continue to be stronger in the
northern outer waters through Sunday with lighter winds elsewhere.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: Canepa/W Pi
MARINE: W Pi
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Area Forecast Discussion
National Weather Service Paducah KY
636 PM CDT Sat Aug 25 2018
.UPDATE...
Issued at 636 PM CDT Sat Aug 25 2018
Updated aviation discussion.
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 325 PM CDT Sat Aug 25 2018
A few areas of enhanced cu have developed this afternoon, most
notably over the higher terrain of southeast Missouri. All
indications from radar and the latest HRRR output are that any
convection will remain shallow and should not result in tangible
precipitation or thunder.
A good consensus exists amongst the 12Z models in a return to
more hot and humid conditions through Monday. High pressure aloft
will keep the area dry, while gusty southerly surface winds will
bring increased heat and humidity back across the region.
The southern fringe of the westerlies will be just north of our
area, and most guidance streams some convection eastward to our
north late tonight and early Sunday. The 12Z GFS is an outlier in
producing QPF over most of our area. The GFS has had a notable wet
bias of late, so will ignore it and keep the area dry.
High temperatures will climb into the lower 90s throughout the
region Sunday and Monday while lows will generally be in the lower
70s each night. Add in the humidity and heat indices will climb
to near 100 throughout the area each afternoon. Winds will
occasionally gust into the teens each afternoon.
.LONG TERM...(Tuesday through Saturday)
Issued at 325 PM CDT Sat Aug 25 2018
The forecast confidence for the Day 4 through 8 time period remains
high for Tuesday through early Thursday. However, confidence from
late Thursday through next Saturday is quite low.
For the time period, both the short and medium range guidance is
quite consistent in progressing a shortwave from the northern Plains
to the east of the Great Lakes Wednesday into Thursday. The
Canadian, ECWMF, and NAM guidance were consistent in timing of the
associated cold frontal passage through the WFO PAH forecast area.
Beyond Thursday, the numerical model guidance solutions diverge with
the Canadian model the driest, followed by the ECMWF, then the GFS
model suite. Given the strength of the cold air advection behind the
frontal passage on Thursday, as well as the degree of ridge building
(albeit low amplitude) behind the cold front, have difficulty
keeping any significant measurable PoPs/Weather in place from
Thursday through next Saturday.
There appears to be some discrepancy between relative position of
the surface frontal zone and the upper level shear zone left by the
trailing upper level trough in the eastern seaboard late in the
week. Would not be surprised if PoPs/Weather get dropped late next
week, but for now a smaller mention of rain is left in for
collaborative purposes.
The zonal and northwesterly flow should keep temperatures at or
below normal through most of next week.
&&
.AVIATION...
Issued at 636 PM CDT Sat Aug 25 2018
Through the 24 hour TAF period, winds are forecast to remain pretty
steady, out of the south to west-southwest and generally under 10
knots. VFR conditions can be expected, with only some mid/high
cloudiness from time to time.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...DRS
LONG TERM...Smith
AVIATION...DB
Area Forecast Discussion
National Weather Service Reno NV
549 PM PDT Sat Aug 25 2018
.UPDATE...
Mid and high clouds are a little thicker associated with the
incoming trough of low pressure as noted on satellite imagery this
evening. These are increasing from the north. The increased
clouds could affect temperatures overnight over northern parts of
the forecast areas while increasing winds late keep some mid
slope areas a little warmer. We will make a few minor adjustments
to sky cover and a few temperatures to account for that
eventuality. Updates out soon.
&&
.SYNOPSIS...
Near average temperatures continue with a few degrees of cooling
for the early part of next week. Dry conditions and typical breezes
are expected through this evening. Breezy winds and critical fire
weather concerns increase for Sunday as a dry trough approaches the
region. No precipitation is expected for the next week.
&&
.PREVIOUS DISCUSSION... /Issued 259 PM PDT Sat Aug 25 2018/
SYNOPSIS...
Near average temperatures continue with a few degrees of cooling
for the early part of next week. Dry conditions and typical breezes
are expected through this evening. Breezy winds and critical fire
weather concerns increase for Sunday as a dry trough approaches
the region. No precipitation is expected for the next week.
SHORT TERM...
A trough moving through the northwestern portion of the CONUS will
brush across northern Nevada on Sunday. With this comes an increased
surface gradient, but little in the way of upper level support to
further increase wind speeds. Peak wind gusts of 30-35 mph
(locally up to 40 mph) can be expected across most areas Sunday
afternoon and early evening which will bring an increased fire
weather risk, choppy conditions to area lakes, and possible
turbulence for aviation. Please see the fire weather section below
for additional details on the increased fire danger. We have also
issued Lake Wind Advisories for western Nevada lakes. The other
concern is blowing dust across the Black Rock Desert. The dust
source region there has been activating the past few afternoons
with lesser wind speeds, so we expect greater coverage to the dust
on Sunday.
General troughiness remains over the region into next week with
temperatures near to a few degrees below normal and dry conditions
continuing. This translates to 70s and 80s for highs in valley
locations and lows in the 40s and 50s, however, colder mountain
valleys could easily drop into the 20s and 30s due to the very dry
air mass in place.
Smoke from ongoing wildfires continue to bring hazy conditions to
the region. Based on the latest satellite observations and HRRR
smoke model trends, thicker smoke is present across northern CA/NV,
with lighter haze elsewhere and this is likely to continue. -Dawn
LONG TERM...Wednesday through next weekend...
Very few changes were made to the forecast since the last update.
A strong ridge over the Aleutian Islands will allow a shortwave
trough to sit off the west coast of the United States, which will
lead to continual southwesterly flow over our region through next
weekend. This will keep temperatures near normal and will also
keep us dry. Typical afternoon breezes can also be expected. By
late next weekend, the operational GFS/ECMWF and their respective
ensembles show the ridge over the Aleutian Islands weakening and
moving westward. However, beyond the breakdown of this ridge,
there is quite a bit of spread in the operational/ensemble
solutions. What does this mean for us? Either a typical late
summer pattern where temperatures remain near normal or a brief
trough could move through during the first week of September
providing windier and slightly cooler conditions. -Johnston
AVIATION...
Hazy conditions will continue as westerly winds transport smoke
downwind of fires in northern California. Slant-wise and flight
level visibility will likely be reduced for areas north of Interstate
80, which includes KSVE and the Black Rock Desert. These conditions
are also likely Sunday. Typical afternoon winds are expected today
with peak gusts around 20 kts, increasing to 25-30 kts for area
terminals Sunday. The strongest gusts will likely occur at KLOL,
KRNO, and KMMH. Blowing dust is also possible across the Black Rock
Desert due to these stronger gusts. -Johnston
FIRE WEATHER...
The base of a broad upper-level trough will provide an increase in
winds Sunday afternoon and evening. The combination of increased
winds and low RH will result in areas of critical fire weather
conditions. As such, Red Flag Warnings have been issued for Sunday.
The favored locations to see gusty afternoon winds (30-35 mph)
are roughly areas along and east of the Highway 395 corridor from
Lassen County into western Nevada. Most zones that were in a Fire
Weather Watch have been upgraded to Red Flag Warnings with the
exception of Zones 271/272/273 (western Lassen/Tahoe/Mono) and
459 (Mineral/southern Lyon counties). These areas remain too far
removed from the strongest winds aloft and as a result will only
see short periods of critical fire weather conditions with gusts
mainly 25-30 mph. Nonetheless, dry conditions are expected
areawide with min RH 5-10% in the deserts and 10-15% through the
Sierra. Fuentes
&&
.REV Watches/Warnings/Advisories...
NV...Red Flag Warning from 2 PM to 11 PM PDT Sunday NVZ450-453-458.
Lake Wind Advisory from 1 PM to 11 PM PDT Sunday NVZ001.
Lake Wind Advisory from 11 AM to 11 PM PDT Sunday for Washoe
Lake in NVZ003.
Lake Wind Advisory from 11 AM to 11 PM PDT Sunday NVZ004.
CA...Red Flag Warning from 2 PM to 11 PM PDT Sunday CAZ270-278.
Lake Wind Advisory from 1 PM to 11 PM PDT Sunday CAZ073.
&&
$$
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