Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/03/17
Area Forecast Discussion
National Weather Service Cleveland OH
948 PM EDT Sat Sep 2 2017
An area of weak low pressure will pass to the north of Lake Erie
later tonight. High pressure will build across the region
Sunday afternoon through Monday evening before a cold front
drops across the southern Great Lakes on Tuesday. Cool Canadian
high pressure will build over the region the second half of the
.NEAR TERM /THROUGH SUNDAY NIGHT/...
Latest HRRR model shows showers will arrive around 05z to 06z in
the morning across Toledo and Findlay. Line will move east and
still looks like a pre trough line will develop over Cleveland
and Mansfield and also move east. Still may hear a rumble or two
of thunder but not enough to mention in the forecast at this
time since lightning has decreased over the last hour or so with
the line. No major changes with this update.
Scattered showers continue to float around the area. The models
still show an area of weak low pressure developing north of the
lake this evening as an upper trough crosses the region. At the
surface...a cold front will cross the area the second half of
the night. There is currently showers and even a few
thunderstorms along this front over WI. The NAM...HRRR...SREF
and a bunch of other guidance show showers blossoming over the
eastern half of the area this evening as the low develops. They
also show some showers with the front...even in the west. With
that said...will go with likely wording in the east and chance
in the west. Just not comfortable keeping things completely dry.
The front itself will be east of the area by 12z. The precip is
expected to cut off quickly behind the front and by daybreak
most of the showers that are left will be downwind of the lake.
Even those areas should dry out by early afternoon as ridging
occurs at the surface. Skies should clear from west to east as
well starting along the I-75 corridor late tonight and reaching
NW PA late tomorrow. Sunday night will be quiet as the local
area remains between systems.
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
High pressure over the Appalachians Monday will slide off the coast
as the day progresses. This will mean warm temperatures and dry
conditions through the first half of the day for everyone. As we
head into the late afternoon and evening hours a cold front will be
approaching northwest Ohio. This could bring a few showers to the
Toledo area before sunset. The chance for showers and storms will
increase rapidly Monday night as the front moves southeast across
The front should stall out off to our southeast Tuesday into
Wednesday, but with a large trough over the area, expect a continued
shot at some off and on showers Tuesday and Wednesday. The more
widespread precipitation should remain to the southeast of the
Temperatures Monday will rise into the 80s for just about everyone,
but will fall sharply behind the cold front. Highs Tuesday will be
in the low 70s with highs on Wednesday not making it out of the
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Several nice short waves should round the bottom of the trough on
Thursday and probably into Friday. H8 temperatures are progged to be
about 5-8C depending on the model. Will have a chance for showers
and given the chance for some lake enhancement, will have somewhat
higher pops in the snowbelt of northeast OH and northwest PA.
Temperatures should be well below normal with highs mostly in the
60s Thursday and Friday and lows inland mostly in the upper 40s.
High pressure will build across the Great Lakes by Saturday and the
trough aloft should lift out and heights could rise quickly. Will
forecast dry weather on Saturday with temperatures recovering into
the 70s but still a couple of degrees short of normal.
.AVIATION /00Z Sunday THROUGH Thursday/...
Most models suggest timing of the upper level shortwave trough
and reflected surface trough will move east across the area
tonight. This will place the line of showers and possibly a
rumble of thunder at Toledo and Findlay around 06z this evening.
The activity appears it will weaken as it moves east while yet
another line of showers develops from Cleveland and Mansfield
moving east. Added mention of the vicinity showers for tonight
in the west but will leave mention of any thunder out of the
forecast at this time due to loss of heating of the day and
weakening trend expected. Expecting mostly VFR conditions
during the latter half of the night. First half of the night
will see lower ceilings ahead of the trough axis moving through
improving to VFR through the rest of the forecast period. Winds
will gradually shift around to the west tomorrow at around 10
OUTLOOK...Non-VFR possible in showers on Tuesday.
Breezy southeast winds will continue across the eastern portion of
the lake this evening. Winds will veer around to the southwest
tonight and eventually to the west by Sunday morning. These west
winds will be brisk, especially across the eastern half and waves
will likely build to 3 to 5 feet and a small craft advisory will
be needed. Winds back to the southwest at around 20 knots for
Monday and increase as a cold front approaches, crossing the
lake early Tuesday morning. Winds do not appear to be too strong
after the cold front with an expansive area of high pressure
encompassing the Great Lakes and much of the central U.S.
OH...Beach Hazards Statement from Sunday morning through Sunday
evening for OHZ012-089.
PA...Beach Hazards Statement from Sunday morning through Sunday
evening for PAZ001.
MARINE...Small Craft Advisory from 10 AM to 9 PM EDT Sunday for
Area Forecast Discussion
National Weather Service Fort Worth TX
954 PM CDT Sat Sep 2 2017
A cluster of storms continues to move south-southeast just beyond
our western counties this evening. The outflow boundary associated
with the complex continues a few miles ahead of most of the rain,
but new development has been regenerating immediately behind the
outflow boundary. Will retain about a 40% chance for rain in our
southwestern counties tonight with lower rain chances across the
remainder of our western and northern counties through the night.
An upper level disturbance currently located near the Abilene area
will provide lift for additional showers and isolated storms
through the night. In addition, hi-res guidance continues to
develop new convection in our northeast counties where a diffuse
surface boundary can be seen in surface observations. With a weak
low-level jet, this area may see some showers or isolated storms
in the overnight hours and have increased PoPs to 30% in our
northeast. Gusty winds of 25-35 mph will be the main hazard with
any convection through the overnight hours.
Otherwise, the remainder of the forecast is in good shape and no
significant changes were needed.
.AVIATION... /Issued 637 PM CDT Sat Sep 2 2017/
An upper level disturbance currently located north of Abilene will
continue sliding south tonight and Sunday, bringing low rain
chances to North and Central Texas. The main concern during the
next 24-30 hours is showers near the DFW airports this evening.
One shower is now occurring in the Arlington/Grand Prairie area,
and other isolated convection will remain possible through 02Z.
However, most of the showers and storms are expected to remain
west of the DFW area. This activity is slowly growing towards the
KACT area and will monitor trends in case an amendment for
convection is needed at KACT. However, most of the activity may
diminish with the loss of daytime heating before reaching the
airport. During the overnight hours and on Sunday afternoon, a low
chance for showers and perhaps and isolated thunderstorm exists,
but potential is too low to mention at any of the TAF sites.
Otherwise, VFR conditions will prevail with mainly light south
winds less than 10 kts, and a mix of cumulus with bases between
5-7 kft and mid and high level clouds.
.SHORT TERM... /Issued 240 PM CDT Sat Sep 2 2017/
The main vort max associated with the shortwave trough axis to our
north appears to be situated near Lawton per water-vapor loops
this afternoon, and is slowly moving southward. With the core of
the parent upper low and associated cooler mid-level air
overspreading the region, we`re seeing an uptick in (agitated)
cumulus across our western counties at this time where surface
temperatures have warmed into the mid 90s, and low-level
confluence is maximized. Hi-res guidance continues to indicate
initial thunderstorm development will be most likely across the
region this afternoon and evening--roughly south and west of
US-287/81 and near and just north of I-20. Fairly deep inverted-V
profiles are noted across this region, which is resulting in DCAPE
values locally exceeding 1000 J/kg. As a result, while there is a
paucity of deep layer shear (15-25 kts), evaporative cooling
beneath the more robust updrafts may result in some strong to
perhaps marginally severe wind gusts (50-60 mph) before more
substantial gains in nocturnal inhibition are realized late this
With such an abundance of DCAPE/dry sub-cloud air, there may be
a potential for some degree of cold pool development this evening
as activity starts to dive southward. Recent runs of the
operational HRRR seem a bit too aggressive in this regard, but a
compromise between the more muted HRRRx and TTWRF seem reasonable,
and will paint a small swatch of 40% PoPs across our far
western/southwestern counties this evening.
We`ll hold onto low shower/isolated storm chances overnight across
roughly the northwestern 2/3rds of the CWA as additional subtle
bouts of isentropic ascent sink southward out of Oklahoma behind
the departing shortwave.
.LONG TERM... /Issued 240 PM CDT Sat Sep 2 2017/
/Sunday Through Next Weekend/
A strong upper disturbance will be dropping south through the Low
Rolling Plains and toward West-Central Texas and The Texas Hill
country. Shortwave energy, though more sheared and weak, will also
be transversing south across the Ark-La-Tex and down through East
Texas Sunday morning. Better moisture will be across the eastern
counties however and will have slightly higher convective chances
there for the morning hours. By afternoon, have continued slight
chances for the afternoon across Central Texas, as the upper
disturbance continues its track southward. With Sunday afternoon
highs expected to rise between 90 and 95 degrees, this will allow
for some steep lower adiabatic lapse rates below cloud base for
gusty winds. Mid level lapse rates look to be 6 deg C/km or less,
so do not expect any threat for even small hail, though brief
heavy downpours will certainly be possible.
A brief, mainly dry period will occur Monday and Monday Night, as
weak subsidence continues in behind the stalled upper disturbance
across Central and South Texas. I cannot rule out isolated, mostly
diurnal convective activity, mainly across the Southwest counties
as temperatures heat up back into the 90s with weak ascent
overhead. Once again, the same intensity rules apply on Monday
versus Sunday, as instability and shear values aren`t really
conducive for any severe weather. A strong cold front will push
south from the Central High Plains and into the Southern Plains of
Oklahoma Monday night and Tuesday morning. The cold front will be
supported by upper level energy diving southward from the Great
Lakes to across the Mississippi Valley and Ozarks during the day
Tuesday. The model solutions aren`t quite as strong or amplified
as yesterday, but there will still be plenty of support for the
cold front to enter our Red River areas by early afternoon, then
exit our Central Texas counties and southern CWA border later
Tuesday evening. Low level CAA will be strong enough along with
the surface pressure gradient for gusty north-northeast winds 15
to 20 mph behind the cold front with vastly cooler temperatures.
In addition, surface convergence along the cold front will combine
with increasing lift aloft and moisture/instability ahead of the
front for scattered showers and storms, a few of which could be
strong with gusty winds, small hail, brief heavy downpours, and
frequent lightning. Though a brief severe storm with damaging
winds can`t be ruled out, the coverage of such a storm would be
isolated at best.
Wednesday will start off brisk and much cooler as temperatures
start off in mid 50s north to mid 60s south. However, clouds will
be moving out early in the morning and the early September
insolation will allow for highs to rebound into the upper 70s and
lower 80s. Winds look to decouple under mostly clear skies
Wednesday with another cool morning Thursday in the 50s to lower
60s, but without the wind. However, surface high pressure will
build in with dry northwest flow overhead for another pleasant day
in the lower to mid 80s. One last cool morning in the 50s/60s
will occur on Friday morning, before the surface high shifts east
with the Eastern CONUS upper trough exiting east away from us as
well. Southeast winds will return with upper ridge filling back in
over the region for a gradual warm up back into the mid-upper 80s
across the area. Despite the south winds, the upper ridge will
keep the skies mostly cloud-free with dry weather throughout next
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 74 93 75 93 76 / 20 20 10 5 5
Waco 72 93 72 93 72 / 10 20 10 5 5
Paris 69 90 71 90 71 / 30 30 5 10 10
Denton 70 92 72 92 73 / 20 10 5 5 5
McKinney 69 92 71 91 71 / 30 20 5 10 5
Dallas 75 93 75 93 76 / 20 20 10 5 5
Terrell 71 92 73 92 73 / 20 30 10 10 5
Corsicana 72 92 73 92 73 / 10 20 10 10 5
Temple 70 92 70 92 71 / 10 20 20 5 5
Mineral Wells 69 93 70 92 70 / 20 10 10 5 5
Area Forecast Discussion
National Weather Service Gray ME
1054 PM EDT Sat Sep 2 2017
Low pressure will approach from the southwest tonight and will
lift northeast through the region Sunday and Sunday night. A
shallow ridge of high pressure will build east through the area
on Monday. A cold front will approach from the northwest Monday
night and will gradually stall over the area on Tuesday. Low
pressure will track northeast along the front Wednesday through
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1045 PM...Despite solid area of rain to our S and W, latest
runs of the HRRR show little more than sprinkles to a couple
hundredths of an inch of rain through southern and western
zones through 16Z, with it being dry elsewhere. For now have
backed off pops a bit overnight by just a bit, but still worth
watching, as best WAA shifts offshore in the morning, and best
deformation associated with developing doesn`t get going in wrn
zones until the afternoon. Otherwise, just a few tweaks to temps
625 PM...Made some adjustments to temps to show faster fall
thru the evening, and then slower falls or steady temps in the
SW two thirds of he CWA, where clouds will be moving in. Also
tweaked pops a bit, and pushed back likely pops until daybreak
or so, as well as the steadier rain, with just some sct SHRA
falling out of the mid level WAA deck possible in the SW after
Previously...Remnants of Harvey will approach from the
southwest overnight bringing increasing clouds and rain toward
daybreak in southwest New Hampshire. Should see a warmer night
with lows generally ranging through the 40s to near 50.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Rain will gradually overspread the forecast area on Sunday and
will last into Sunday night before tapering to showers after
midnight. Rainfall amounts will range from a half to one inch.
Highs on Sunday will range from the mid 50s to lower 60s. Lows
Sunday night will bottom out in the upper 40s to mid 50s.
.LONG TERM /MONDAY THROUGH SATURDAY/...
Mon looks to be the quiet day of the extended...as the remnants
of Harvey race off to the NE and we break into warmer air behind
the occlusion. The mtns may see some straggling clouds and maybe
a sprinkle...but overall a dry day. H8 temps will be increasing
thru the day...especially towards 00z Tue...with gusty WSW
flow...so we may make a late run at the 80s across Srn zones.
The next s/wv trof and attendant front drops in Tue. With H8
temps near 15C...some mid 80s possible in the typically warmer
spots especially if clouds and precip stay W. The problem moving
towards midweek however will be a building ridge across the Wrn
Atlantic. This will halt the frontal progression...and lead to
it stalling over or very nearby the forecast area. This
complicates the forecast because it will be a focus for
precip...but not always steady precip. Some of it may be tied to
diurnal convective processes...while at other times weak waves
moving thru the trof may result in more widespread rainfall. The
timing of these smaller waves has been jumping around the model
guidance in recent runs...so exact timing is highly uncertain.
That being said...a wave around midweek...Wed/Thu and another to
end the week looks possible before the front moves far enough E
to drop PoP to chance or lower. With deep...moist flow along the
East Coast some of the precip may be on the heavier side.
The afternoon Hurricane Irma update has changed little from
yesterday. Any potential impacts are still a week or more away
and it being nearly 1500 miles from the nearest land. To put it
in perspective...Irma is closer to Africa than it is to the
U.S. Its current position in the Atlantic Basin continues to
suggest the likelihood of impacts to the East Coast are
low...however a SW push over the next couple of days will bring
Irma into a more favorable location. Ensemble guidance
continues to show a wide range of solutions...so any forecast
you see is low confidence at this time. Continue to follow the
National Hurricane Center for the most up to date
information...and regardless of eventual impacts or lack thereof
from Irma it is always a good idea to review your hurricane
preparedness and emergency kits.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Short Term...VFR tonight. IFR/LIFR ceilings developing Sunday
and persisting through Sunday night.
Long Term...Forecast area should break into the warm sector
Mon...allowing for VFR conditions to return to all terminals.
This will be followed quickly by the next frontal system Mon
night into Tue. HIE and LEB will see MVFR or lower conditions
first...as clouds and SHRA move into the region from the W.
Eventually MVFR or lower conditions will overspread the entire
area Wed. There may end up being variable conditions as a series
of waves moves along the stalled front...but overall I expect
a large part of the middle of the week to be less than VFR
Short Term...Winds will be on the increase Sunday and will reach
SCA levels by Sunday afternoon.
Long Term...Winds and seas will remain near marginal SCA
thresholds...especially outside of the bays thru Mon. Winds will
diminish towards midweek...but seas look to remain near 5 ft
thru the end of the week.
MARINE...Small Craft Advisory from 8 AM Sunday to 6 AM EDT Monday for
Area Forecast Discussion
National Weather Service Lincoln IL
901 PM CDT Sat Sep 2 2017
Issued at 900 PM CDT Sat Sep 2 2017
A weak surface trough/front progressing south through Illinois is
creating a band of lift and showers in NE IL and west-central IL.
So far, the middle portion of the line (over our forecast area) has
not developed enough lift for showers, or even weak radar
returns/sprinkles. Many of our high resolution models are
depicting the line of showers filling in across our counties in
the next couple hours, and progressing south the rest of the
night. The 00z ILX sounding indicated an increase in moisture in
the 850-750mb layer, supporting increasing potential for isolated
showers. Will continue with progressing a band of slight chance
PoPs from N to S through our area tonight.
Areas without much cloud cover in eastern IL have seen temps drop
quickly toward forecast lows, with 58 already in Champaign, 57
in Danville, and 54 in Robinson. Farther west under the mid
clouds, temps have remained warmer in the mid 60s. Have adjusted
low temps down a degree or two, but do expect advancing clouds to
slow the temp falls in the eastern areas, stabilizing the diurnal
Updates this evening included the weather/PoPs, sky, and low
temps/hourly temps. The latest forecast info is already available.
.SHORT TERM...(This evening through Sunday)
ISSUED AT 245 PM CDT Sat Sep 2 2017
Latest surface map shows upstream frontal boundary extending from
near the Minnesota Arrowhead into southeast Nebraska. Clouds head
of this feature have been struggling to make much headway into
central Illinois, with dry low levels seen in GOES-16 water vapor
imagery and surface temp-dewpoint spreads on the order of 20-25
So far, the associated shower and thunderstorm activity has been
ahead of the boundary in Wisconsin, as a shortwave pushes through
that area. However, the lower levels will begin moistening as the
southwest flow gets more established over the next several hours.
While not a great amount, a few showers continue to be indicated
on high-resolution models, as well as the NAM and ECMWF to an
extent. 20% evening PoP`s were added across the northern CWA
earlier, and will go ahead and add some to the south half after
midnight. Any lingering rain should be out of the far southeast
CWA early Sunday, with sunshine prevailing the rest of the day.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 245 PM CDT Sat Sep 2 2017
Still looking like a toasty Labor Day. With 850 mb temperatures
near +21C and good mixing from southwest winds gusting to near 25
mph, have gone with highs at or above 90 over most of the CWA.
Some small variations in the morning model guidance regarding the
speed of the strong cold front, but in general the front should be
through most of the CWA by midnight. Currently looks like the front
should be through the northwest CWA before the rain really gets
going, so will only go with slight chance PoP`s there. Elsewhere,
have continued with the 40-50% PoP`s Monday night, with just a few
showers lingering in the far southeast Tuesday.
Evolution of the colder, long-wave pattern continues to be the
main focus from Tuesday onward. 850 mb temperatures progged to be
down to around +4C by midday Wednesday, and MOS guidance and
blends are starting to latch on to a downward trend in lows
midweek. May not be cold enough though, given dew points in the
mid 40s early Wednesday morning, so this remains the concern
going forward. Regarding rain chances, steep mid level lapse rates
and the deep trough overhead will be conducive to a few showers,
though most of them will be downwind of Lake Michigan.
The trough will slowly lift out late week, but temperatures should
remain below normal through the end of the week.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 704 PM CDT Sat Sep 2 2017
The approaching warm front/surface trough will continue to drift
E-SE across our forecast area tonight. At this point, there is
plenty of dry air in place ahead of the front, so precip will be
limited by that. However, a majority of the high resolution models
depict a band of radar returns developing from west to east across
central Illinois this evening. The band is projected to slowly
progress south of I-72 after midnight, with a few sprinkles even
possible toward Lawrenceville at sunrise on Sunday.
The MVFR BKN050 clouds and VCSH were left in several hours of the
evening portion of the 00z TAFS at all sites. Most areas will
remain dry, and even the locations that see rain will probably
just get trace amounts.
The next concern is IFR/LIFR fog and IFR clouds late tonight
mainly NW of the Illinois river, but possibly as far south as SPI.
The HRRR is most pessimistic with fog and low clouds around PIA,
with IFR clouds also at SPI. Have introduced a tempo for IFR
VIS at PIA and MVFR vis at BMI and SPI.
Winds will start out SW to W at less than 10kt tonight, then
become northwest tomorrow at 7-9kt.
Area Forecast Discussion
National Weather Service Melbourne FL
944 PM EDT Sat Sep 2 2017
Tonight...Cluster of convection has pushed offshore with lingering
light rain just exiting the north coast. The MAV MOS doesn`t show
any POPs after 06z, but currently there`s an upstream cluster of
convection off the southwest Florida coast. The HRRR model shows
it falling apart, but it does show that some light rain might
affect the south. Will carry small shower chances there until
around midnight Considerable debris cloudiness may linger due to
the diminishing convection in the Gulf. Noticed MOS had quite a few
min temps of 71 or 72 degrees, but this looks a little too low and
will stay our current forecast of mid 70s, except for a pocket of
lower 70s over the interior south. Overall, very little change to
the previous forecast.
.AVIATION...Conditions look VFR overnight and past sunrise Sunday.
the GFS and ECMWF MOS POPs came in lower for tomorrow, so coverage
of afternoon storms shouldn`t be nearly as high as today.
Tonight-Sunday...Weak high pressure ridge over the waters will
provide a light south-southwest wind tonight, then the models show
variable winds less than 10 knots on Sunday. Seas near shore are
1-2 feet and around 3 feet offshore and don`t see much change
tomorrow. The models are indicating less coverage of afternoon
storms over land, so the prospects for offshore moving storms will
be lower than today.
The Melbourne Airport had a 4.62 inch deluge on Saturday, which
easily broke the daily rainfall record. The previous record
rainfall for Sep. 2 in Melbourne was 2.35 inches set in 1977.
Area Forecast Discussion
National Weather Service Norman OK
936 PM CDT Sat Sep 2 2017
Updated the the chance of rain for this evening/tonight. Also
updated temperatures/cloud cover/wind forecast based on current
Showers/storms have dissipated across Oklahoma this evening as
surface temperatures cool and convective inhibition increases.
GOES-16 mid-level water vapor imagery and RAP analysis indicates a
mesoscale convective vortex (MCV) is currently centered across
western north Texas. Ascent from the MCV will result in a
continued chance showers/storms across parts of western north
Texas--primarily across Wichita, Clay, Archer, and Baylor
counties--this evening. Do not expect any severe weather due to
Short-term models indicate that this MCV is forecast to slowly
shift southward through tonight. Therefore, with the lack of any
mid/upper-level ascent and no forecast low-level jet tonight,
kept a dry forecast after 06Z for now.
.PREV DISCUSSION... /issued 558 PM CDT Sat Sep 2 2017/
Light east and southeast winds will continue with some mid clouds
early this evening across the south. Otherwise, mainly clear skies
expected through remainder of forecast. Isolated storms possible
across southern Oklahoma south into north Texas next few hours, but
chances remain too low to mention in the TAFs at this point.
PREV DISCUSSION... /ISSUED 158 PM CDT Sat Sep 2 2017/
Latest loop of GOES-R water vapor channels shows a mid-level
circulation at the base of a shortwave trough over western north
Texas. Weak low-level convergence and diabatic heating of a
fairly moist environment may lead to at least isolated convection
from mid-afternoon through early evening. This would be confined
mostly to north Texas and far southern Oklahoma. Instability and
shear are not supportive of organized/severe thunderstorms, but
a deeply mixed boundary layer could support microburst potential
with brief strong to severe gusts, especially over far
southwestern portions of our area where mid-level dry air is most
extensive. Any activity should diminish and/or shift south later
Deep subsidence is evident in the water vapor imagery behind
this shortwave upstream across Kansas and northern Oklahoma, and
this will support clear and dry conditions through Sunday. The
only exception will be perhaps some diurnal cumulus development
Sunday afternoon. Most locations will reach the low 90s for high
temperatures Sunday which would be one of the few days of the last
several that we`ve been above normal.
On Monday, slight veering of low level flow may support temperatures
that are a few degrees warmer than Sunday. We will transition
quickly into a much more amplified large scale pattern early next
week. A fairly potent mid-upper trough will emerge from the Canadian
prairies region into the northern Plains and quickly move
southeast late Monday. This will force a fairly substantial cP
cold surge through the Plains into our area Tuesday morning.
Surface pressure rises of around 15 hPa are indicated in the
models across the Colorado plains and although this will lessen
some with equatorward extent Tuesday, it should still support
breezy conditions. Increasingly deep mixing late Tuesday morning
into Tuesday afternoon could support wind gusts to 35 mph,
particularly across western Oklahoma, before pressure gradient
weakens late in the day. We increased winds above model consensus
and much closer to raw guidance.
These progressive frontal regimes tend to underwhelm us with regards
to precipitation production, and this case will probably be no
exception. Band of stronger mid-level flow and ascent will be
confined to the cold side of the boundary. It seems that our best
chances for convection will be 1.) if any anafrontal convective
development across east and central Kansas can make it into
northeast portions of our area in the predawn hours Tuesday morning,
and 2.) if diurnal convection can form Tuesday afternoon along
the slower segment of the front to the east near the southern
extent of the Ouachita mountains where deeper moisture will
reside, and possibly further west into our far southeast counties.
Scenario #2 seems unlikely to impact our area given the trend in
model guidance for a faster frontal progression. Thermodynamic
profiles north of the front will be unfavorable for convection
given sharp frontal inversion and resultant stable boundary layer
seen in model forecast soundings.
We weighted temperatures Tuesday toward the cooler raw guidance and
away from statistical and bias corrected guidance. This may not be
cool enough, particularly if mid-level clouds are more extensive
and further limit diabatic heating. Temperatures should be around
10 degrees below normal for at least the northern 2/3rds of the
area. Little moderation is expected until Thursday when low level
flow veers to easterly/southerly and mid-level heights increase.
Differences in medium range deterministic guidance and large
ensemble spread develops by late week. Smaller-scale shortwave
troughs that show up in deterministic guidance were washed out in
the EPS and GEFS ensemble mean. Nevertheless, the larger scale
pattern of eastern CONUS troughing/low height anomalies and high
amplitude ridging in the west is apparent. Trends in ensemble mean
guidance suggests perhaps a slower eastward progression of eastern
trough and overall shorter wavelength of the flow pattern. This
generally means mean northwesterly flow for us and below climo
PWATs, and generally and unfavorable pattern for impactful
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 68 91 69 94 / 0 0 0 0
Hobart OK 67 92 69 96 / 0 0 0 0
Wichita Falls TX 70 93 71 96 / 10 10 0 0
Gage OK 64 92 64 96 / 0 0 0 0
Ponca City OK 67 93 68 96 / 0 0 0 0
Durant OK 71 90 70 92 / 10 10 10 0
Area Forecast Discussion
National Weather Service Seattle WA
259 PM PDT Sat Sep 2 2017
.SYNOPSIS...A strong upper ridge will be over the region through
Wednesday. High temperatures will be well above average. A weak
upper trough will bring cooler weather Thursday and Friday.
.SHORT TERM...Sunny warm weather will continue through Tuesday.
Some night and morning low clouds and fog is possible for the
coast and through the Strait and some areas between Everett
and about Mt. Vernon--but any fog or low clouds that do form
will burn off pretty quick Sunday morning. The marine air will
be even shallower Monday morning for just some patches of fog.
The warm thermal trough over the western U.S. will bulge north
toward Western Washington through early next week and temps
should peak Tuesday. Some smoke will arrive as well as winds
turn southerly aloft and light low level offshore flow develops
early next week.
.LONG TERM...A weak upper trough and southerly flow aloft could
bring a chance of showers or thunderstorms around the middle of
the week. Onshore flow will develop and cooler temps are in the
forecast as marine air moves back into Western Washington--and
the chance of showers might continue into the end of the week.
The GFS and ECMWF differ quite a bit in the timing and details.
.FIRE WEATHER...Fuels are already about as dry as they get around
here, and now we have a prolonged stretch of hot and dry weather
ahead. Monday and Tuesday will be the most critical fire weather
days due to low-level offshore wind flow.
Wind: Northeast gradients will develop early Monday morning. Over
the northwest Olympic Peninsula near Forks, northeasterly downslope
breezes will lead to critically low RH with a moderate breeze on
Monday and possibly Tuesday morning.
On Tuesday morning, the Seattle-Wenatchee pressure gradient will
strengthen to -4 to -7 mb. This will support east winds on Tuesday
morning between the Cascade Crest and the lowlands gusting around 20
to 30 mph. When combined with RH less than 35%, this will be another
area of critical fire weather.
The mid-level Haines Index will rise to its highest value of 6 on
Monday, in combination with ground-level relative humidity below 25
percent over the mountains. Mid-level Haines 6 indicates a dry and
unstable mid-level air mass (850-700 mb). It is associated with
active fire behavior on new and existing fires, especially above
1500-2000 feet elevation, i.e. the Olympic and Cascade Mountains.
Mid-Level Haines 6 will last until Wednesday morning over the
Olympics, and it will last until Wednesday evening over the
For all of these reasons, have issued Fire Weather Watches this
afternoon for the mountain zones, and for the northwest Olympic
Peninsula. Even where Fire Weather Watches are not in effect, fuels
are impressively dry. Even a little wind will cause rapid rates of
spread through tall grass and volatile Scotch Broom fuel types.
Please do your part to avoid starting new wildfires. Haner
.AVIATION...A broad and strong upper ridge over the area will give
westerly flow aloft through this evening. The flow aloft will
become more southwesterly late tonight through Sunday as the ridge
moves off to the east. At the surface, a ridge of high pressure
extends west from southern British Columbia across northern
Vancouver Island then southward through the offshore waters. A
thermal trough sits from Western Oregon into eastern Washington.
The air mass is stable and dry with shallow moisture off the
Expect very good VFR conditions to continue through this evening.
Smoke from forest fires in the Cascades is expected to remain east
of the Cascade crest. Visible satellite imagery shows an area of
stratus and fog extending from about Cape Flattery southwestward
over the coastal waters. This low level moisture will move just
onshore over the Pacific coastal zones this evening and persist
through midday Sunday before burning off over land areas. Some of
this stratus and fog will get pulled eastward through the Strait
of Juan de Fuca to the western portions of Whidbey Island late
tonight and will burn off by midday Sunday. Stratus and fog is
not expected to affect any of the terminals except for KHQM and
As the flow aloft becomes more southwesterly late tonight through
early Sunday morning, an extensive area of elevated smoke from
wildfires over southwestern portions of Oregon is expected to clip
the southern half of Western Washington. The HRRR model`s smoke
depictions take the elevated smoke east of the area by midday
KSEA...Clear skies. Northerly wind 5-10 knots. Elevated smoke
moving by to the southeast of the terminal may reduce visibility
aloft to the south and east of the terminal between 09Z and 16Z.
.MARINE...A ridge of high pressure extends west and southwest from
Southern British Columbia into the Oregon offshore waters. A weak
thermal trough extends from the interior of Western Oregon into
eastern Washington. The combination of ridging to the north and
some troughing to the south and east of the area will result in
north to northwest flow over the waters through Sunday. Small
craft advisories are in effect for the coastal waters from James
Island southward and for the eastern two thirds of the Strait of
Juan de Fuca through midnight tonight. Little change in the
weather pattern is expected on Sunday. Another round of small
craft advisories is likely from midday Sunday through Sunday
evening for the same locations.
A stronger thermal trough will develop northward into the coastal
waters Monday and Tuesday as offshore flow increases. The thermal
trough will shift inland midweek giving a marine push starting
late Tuesday night or Wednesday with timing uncertain at this
WA...Fire Weather Watch from Monday morning through Tuesday afternoon
for North Coastal Lowlands.
Fire Weather Watch from Monday afternoon through Wednesday
evening for West Slopes of the Central Cascades Generally
above 1500 Feet.
Fire Weather Watch from Monday afternoon through Wednesday
evening for West Slopes of the North Cascades Generally
above 1500 Feet.
Fire Weather Watch from Monday morning through Wednesday morning
for East Portion of the Olympic Mountains-West Portion of
the Olympic Mountains.
Red Flag Warning from noon to 8 PM PDT Sunday for East Portion
of North Cascades National Park/Lake Chelan National
PZ...Small Craft Advisory until 1 AM PDT Sunday for Central U.S.
Waters Strait Of Juan De Fuca-Coastal Waters From James
Island To Point Grenville 10 To 60 Nm-Coastal Waters From
James Island To Point Grenville Out 10 Nm-Coastal Waters
From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal
Waters From Point Grenville To Cape Shoalwater Out 10 Nm-
East Entrance U.S. Waters Strait Of Juan De Fuca.
You can see an illustrated version of this discussion at
Area Forecast Discussion
National Weather Service Shreveport LA
1014 PM CDT Sat Sep 2 2017
To wx/pops/sky for many of our counties and parishes.
Water vapor shows a really vigorous vort S of the Red in TX. It is
going where is does not want to go like Peter. Is being forced S
by the upper ridge, but should shear Eastward. Then new Nam is on
it and so are we with neighbors too. It will not be much and
mostly middecky to start with showers, but any mature cells will
progate SE with NW flow aloft. Spell check got my 1013. /24/
.PREV DISCUSSION... /issued 633 PM CDT Sat Sep 2 2017/
VFR conditions will continue through the 03/00Z TAF period. Areas
of AC and cirrus will expand this evening and overnight across NE
TX/SW AR/N LA, along and ahead of a weak E to E shortwave trough
over the Red River Valley of Srn OK/N TX that will drift S into
the region late. Can`t rule out patchy FG developing late tonight,
but this may be negated by the elevated cloud cover expected to
expand over the region. Isolated -SHRA may also develop overnight
through Sunday across portions of extreme NE TX/SE OK/SW AR near
the trough, but low confidence precludes mention in the TXK/ELD
terminals attm. Another sct cu field should develop over the
region by 16-17Z, with areas of AC/cirrus expected to persist as
well. Lt/Vrb or calm winds tonight will remain Vrb 5kts or less
PREV DISCUSSION... /issued 355 PM CDT Sat Sep 2 2017/
A weak shortwave trough is moving south out of Southwest Oklahoma
and into Western North Texas. An enlongated area of ascent and
vorticity with this trough has supported the development of some
isolated showers along and north of Interstate 30. The better
upper support and better chances for rain will be far to the west
tonight into Texas. Several of the models keep isolated showers in
the forecast through the overnight hours across Northeast Texas,
Southeast Oklahoma, and adjacent portions of Southwest Arkansas.
It is also worth noting that the latest HRRR completely dissipates
any shower activity early this evening with the loss of daytime
instability. I will stay conservative and maintain slight chance
PoPs through the overnight hours. Rain chances may be slightly
better Sunday morning as daytime heating results in some more
instability, but rain chances will be decreasing through the day
as the shortwave drifts southwest and farther away from the area.
After a quiet and dry Monday, our attention will turn to the next
major cold front due to arrive on Tuesday. A strong upper trough
will move southeast from Canada and dig into the eastern half of
the country. Combined with the front, this will provide more than
enough large scale forcing for scattered showers and thunderstorms
across most of the area on Tuesday and into early Wednesday. A
widespread severe weather threat is not anticipated at this time.
In fact, much of the rain may be post-frontal. Rain chances should
end by the daytime hours of Wednesday as the cold front quickly
A drier and significantly cooler airmass will filter into the
region behind the departing front on Wednesday. Daytime high
temperatures will likely only warm into the upper 70s and low 80s
through the remainder of the extended periods. Overnight low
temperatures should fall into the 50s areawide Wednesday
night/Thursday morning and Thursday night/Friday morning. I would
not be surprised to see temperatures Thursday morning in the upper
40s in a few locations in the terrain of Southeast Oklahoma and
Southwest Arkansas. A building upper ridge over Mexico and Texas
combined with a strong surface high pressure should keep the
weekend rain free.
.PRELIMINARY POINT TEMPS/POPS...
SHV 70 91 72 91 / 10 20 10 10
MLU 66 90 68 92 / 10 10 0 10
DEQ 68 90 69 91 / 30 20 0 10
TXK 69 90 70 90 / 20 20 0 10
ELD 66 89 69 90 / 10 20 0 10
TYR 70 89 71 90 / 20 30 10 10
GGG 70 90 70 91 / 10 20 10 10
LFK 70 92 71 92 / 10 20 10 10
Area Forecast Discussion...UPDATED
National Weather Service San Angelo TX
639 PM CDT Sat Sep 2 2017
The main aviation forecast concern is with thunderstorms this
evening and early tonight. Scattered showers and thunderstorms
across the Big Country and Concho Valley areas will continue
to move/develop to the south-southeast through this evening and
into early tonight. Most of the convection should dissipate by or
shortly after Midnight. The main efects should be at the KABI,
KSJT and KBBD terminals. Temporary reductions in ceilings and
visibilities are expected in locally heavy rain accompanying the
convection, and localized wind gusts over 35 knots are possible.
Following dissipation of the showers/thunderstorms, gradually
clearing skies and VFR conditions are expected overnight into
Sunday. A few showers and thunderstorms will be possible by
Sunday afternoon along/south of a San Angelo to Brownwood line,
but low confidence in placement precludes a mention in our TAFs
at this time. Outside of convective activity, wind speeds will
be mostly less than 10 knots.
.PREV DISCUSSION... /issued 324 PM CDT Sat Sep 2 2017/
(Tonight and Sunday)
Scattered showers and storms developing across the Big Country as
expected this afternoon, as a potent shortwave dives south across
the South Plains. High resolution models like the TTU WRF and the
HRRR allow this convection to blossom and sag south this evening
into the Concho Valley and Heartland as well. Increased rain chances
for this evening across much of the area. Upper level support fades
across the area for Sunday, but afternoon heating and adequate low
level moisture will remain. Will keep the isolated storms in the
forecast for Sunday, roughly along and south of a Brownwood to San
Angelo line. As for temperatures, temperatures have returned to
seasonal normals after a few days of relatively cool readings.
(Sunday night through Monday)
Isolated to scattered showers and thunderstorms will be possible
Sunday evening, mainly for areas south of Interstate 20. Overnight
lows will be close to seasonal normals, in the mid to upper 60s.
Highs on Monday will remain near normal, in the low to mid 90s, with
south winds of 5 to 10 mph.
A large upper level trough is forecast to swing across the northern
Plains late Monday, then toward the Great Lakes Tuesday. This will
send a cold front into the northern Big Country Tuesday afternoon,
then through the rest of the area Tuesday evening. Isolated to
scattered showers and thunderstorms will be possible along and just
behind the front, with rain chances decreasing from north to south
late Tuesday into early Wednesday. Cooler temperatures are
anticipated behind the front along with gusty north winds. Highs
Wednesday and Thursday will mainly be in the 80s, with overnight
lows in the mid 50s to near 60 degrees. A slow warm up is then
forecast for the end of the week.
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 91 69 93 / 40 10 10 5
San Angelo 68 93 67 93 / 50 20 20 5
Junction 68 91 66 92 / 20 20 20 5
Brownwood 69 90 68 91 / 50 20 20 5
Sweetwater 68 91 69 91 / 30 5 5 5
Ozona 67 91 66 90 / 20 20 20 5
Area Forecast Discussion
National Weather Service Tucson AZ
300 PM MST Sat Sep 2 2017
.SYNOPSIS...A chance of showers and thunderstorms continues mainly
west of Tucson into Sunday. We`ll then keep enough moisture for
isolated to scattered afternoon and evening thunderstorms during the
.DISCUSSION...Fairly thick cloud shield has limited shower and
thunderstorm development across southeast Arizona during the past
several hours. KEMX WSR-88D depicted an isolated cell near Picacho
Peak moving rapidly northwestward as of this writing. Isolated to
scattered areas of virga or perhaps sprinkles extended from near the
Tucson metro area westward into central Pima County. Meanwhile,
stronger showers/tstms were just north of western Pima County but
outside of this forecast area.
The official forecast continues with scattered showers/tstms from
western Pima County southeastward into Santa Cruz County this
evening. Isolated showers/tstms may yet occur across the Tucson
metro area northwestward into southern Pinal County early this
evening. There is the potential for blowing dust northwest of Tucson
into south central Arizona if strong thunderstorms develop. Various
HRRR solutions as well as the Univ of AZ WRF-GFS suggest that the
bulk of showers/tstms will be west of this forecast area later
The PoPs were reduced to depict a slight chance of showers/tstms
west of Tucson late tonight into Sunday. If the high resolution
solutions are reality, dry conditions will occur Sunday morning,
then another round of showers/tstms west of Tucson Sunday afternoon.
Perhaps more detail than is necessary, but am trying to refine the
Thereafter, there were only very minor modifications made to the
gridded data PoPs and temps Labor Day into next Saturday. The 02/12Z
GFS/ECMWF/CMC deterministic solutions continued to depict strong
high pressure aloft to remain over the western CONUS Monday into
next Saturday. A fairly low grade shower/tstm potential exists daily
Monday through Friday. However, a cold front moving westward across
southern New Mexico and encroaching upon eastern sections, as well
as enhanced northeasterly mid-level steering flow, may provide
increased shower/tstm coverage area-wide Tuesday afternoon/evening.
High temperatures this forecast period will mainly be quite close to
seasonal normals of a few degrees above normal depending upon
.AVIATION...Valid thru 04/00Z.
Scattered -TSRA/-SHRA mainly west to south of KTUS this evening,
then isolated -TSRA/-SHRA west of KTUS late tonight into Sunday
afternoon. Otherwise, VFR conditions into Sunday afternoon. Surface
wind diminishing to less than 12 kts early this evening and
continuing variable in direction into Sunday afternoon. Aviation
discussion not updated for TAF amendments.
.FIRE WEATHER...Scattered showers and thunderstorms west to south of
Tucson this evening, then isolated showers and thunderstorms west of
Tucson late tonight into Sunday. Isolated to scattered afternoon and
evening thunderstorms area wide Monday into next Saturday. 20-foot
winds will generally be terrain driven less than 15 mph Sunday and
Monday. A return to an east to southeast component for the 20-foot
winds is forecast to occur Tuesday and continue into the latter part
of the upcoming week.
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Las Vegas NV
850 PM PDT Sat Sep 2 2017
.SYNOPSIS...Isolated shower and thunderstorm activity is expected
to weaken late this evening over the Mojave National Preserve and
the Colorado River Valley. Chances for storms will spread to the
rest of the region Sunday as moisture overspreads the area. Storm
chances will decrease in most areas Monday as high pressure begins
to build. However, storms may continue each afternoon as low-grade
monsoon moisture is recycled each day.
.UPDATE...Line of strong thunderstorms that produced gusty
winds/heavy rainfall between Dolan Springs and Kingman is starting
to weaken over far southern Nevada and the Mojave National Preserve.
Center of Tropical Depression Lidia was located just northeast of
the Baja Spur. Satellite indicates outer band of high clouds as far
north as Lake Havasu City. Outflow boundary has pushed deeper
moisture northward as far as Las Vegas. Can not rule out a stray
thunderstorm or shower popping up overnight. No update this evening.
.PREV DISCUSSION...201 PM PDT Sat Sep 2 2017
.SHORT TERM...Through Monday.
The Gulf Surge that came up the Colorado River Valley earlier
today has all but stopped between Lake Mohave and Lake Mead this
afternoon. To the south, dew points in the 60`s were present along
the river, with upper 40s and 50s elsewhere south of I-15. This
low-level moisture will provide a decent environment for storms to
propagate west into the area from the Mogollon Rim. Though the
latest HRRR runs have decreased in strength, there are still
indications that a cold-pool driven complex could push into Mohave
County to the Colorado River Valley late this afternoon and this
evening. If this does occur, gusty (potentially severe) winds
will be the primary concern. Additional showers (possibly virga)
will then be possible overnight in an arch from Kingman to the
Spring Mountains, to Owens Lake overnight as the leading edge of
the moisture boundary (associated with remnants from TS Lidia)
pushes north across the region.
For Sunday, ample moisture will be in place for isolated to
scattered storms. Storms will be most likely over the high terrain
across the region, with little more than diurnal heating creating
Moisture will be to wane on Monday as high pressure begins to
build over the region. However, storm chances will continue
across the high terrain of the southern Great Basin and Mojave
Desert with moisture trapped under the ridge.
.LONG TERM...Tuesday through Friday.
The medium range models indicate a possible transition to a fairly
deep trough by next weekend, especially the ECMWF solution.
Meanwhile, an amplified ridge is forecast to be over the western
states Tuesday while a closed slow spins off the central California
Coast. This will provide hot conditions with temperatures several
degrees above normal. In addition, the east to southeast flow
between the two circulations will persist through Wednesday over our
forecast area and allow some moisture to be drawn up from Arizona
leading to chances for afternoon and evening thunderstorms,
particularly over the higher terrain. A deep trough extending from
the Pacific Northwest to central California then comes into the
picture Thursday and is forecast to progress inland late Thursday
through Saturday. The ECMWF digs it down over southern California
Saturday as a closed low while the GFS keeps it over northern Nevada
and Utah as a more open wave. Confidence in the details is low for
next weekend and we will need to watch for increasing shear Thursday
and Friday combined with any lingering moisture which can lead to
more organized thunderstorms. Temperatures will be on the decline
and will be almost cool (at night) next weekend if the ECMWF comes
close to verifying.
.AVIATION...For McCarran...Outflow wind gusts to 30 kts from
the S-SE expected thru 05z, with southerly winds around 10 kts
overnight. Light and variable winds Sunday morning will tend to
favor an easterly direction less than 10 kts Sunday afternoon. SCT
to BKN above 14kft through the forecast period.
For the rest of southern Nevada, northwest Arizona and southeast
California... Isolated showers and thunderstorms are possible across
northwest Arizona, far southern Nevada, and eastern San Bernardino
County overnight. Gusty winds associated with an outflow boundary
will continue moving westward across San Bernardino County tonight.
SCT to BKN above 14kft through the forecast period with cigs down to
10kft at times. The rest of the region will see generally light
diurnal winds with FEW to SCT above 14kft.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
For more forecast information...see us on our webpage:
http://weather.gov/lasvegas or follow us on Facebook and Twitter