Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/19/21
Area Forecast Discussion
National Weather Service La Crosse WI
1039 PM CDT Wed Aug 18 2021
.SHORT TERM...(This evening through Thursday night)
Issued at 152 PM CDT Wed Aug 18 2021
Another quiet day with area on western side of large surface ridge.
Southerly flow making for gradual warming trend each day and night,
and added moisture allowing for a bit more diurnal cumulus.
Even with gradient flow starting to tighten up a bit, low level flow
remains weak enough for patchy valley fog again tonight, especially
on Wisconsin side closer to ridge axis.
Surface dew points expected to climb a little more again tomorrow so
will start to see some heat indices into the 90s, otherwise
another quiet day on tap.
.LONG TERM...(Friday through Wednesday) Issued at 152 PM CDT Wed
Aug 18 2021
Friday evening into Saturday morning remains the focus of the
forecast as an active weather pattern returns for the weekend into
next week.
A robust, negatively tilted trough moves northeastward from the
Rocky Mountains across the northern plains and arrives in the Upper
Mississippi Valley Friday evening. The 18.00 ECMWF and 18.12 NAM
continue to obtain a slower propagation into the area while the 18.12
GFS trends around 6 hours faster.
An abundance of moisture advection and shear, along with sufficient
instability mainly west of the Mississippi River, could lead to
strong to severe storms in the forecast area. The best environment
for severe storms appears to be a bit further west into central and
western Minnesota where the moisture convergence, deep layer shear,
and CAPE are stronger and more favorably aligned. SPC highlights
this region as well in their Day 3 severe weather outlook with a
slight risk extending into southeastern Minnesota and northeastern
Iowa.
If the slower propagation verifies, severe weather will be less
likely and later Friday night. We will continue to monitor the
timing and model differences with this system as the week
progresses.
Lingering showers and storms will clear out by midday Saturday
leading to a dry period before the passage of the next shortwave
late Sunday into Monday. Periodic rain chances persist through the
rest forecast period but are not well resolved in the models at this
time.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1035 PM CDT Wed Aug 18 2021
Main concern the rest of tonight is potential for valley fog to
creep into LSE towards daybreak. Still a decent overall fog setup
with surface ridge extending into the region and a slight increase
in low level moisture. RAP forecast soundings have also been
trending slightly closer to near saturation at the surface around
daybreak. Current T/Td separation and surface winds at LSE
suggest MVFR fog is possible, but breezy conditions just above
the surface should prove to be a limiting factor for IFR or
worse. Similar to previous nights, expect plenty of valley fog in
the tributaries and likely some in the main Mississippi channel.
Perhaps a slightly better chance this time for some to sneak into
LSE for a few hours. VFR rest of the period with southerly winds
generally around 10 knots or less and some afternoon cumulus.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...TJS
LONG TERM...KAA
AVIATION...Kurz
Area Forecast Discussion
National Weather Service Burlington VT
806 PM EDT Wed Aug 18 2021
.SYNOPSIS...
Remnants of Tropical Storm Fred will produce widespread rainfall
starting late tonight. A Flash Flood Watch is in effect for
portions of the southern Adirondacks along with southern and
central Vermont where 1 to 3 inches of rain with locally higher
amounts is expected. Warm and humid conditions with chances of
showers will continue into the weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 719 PM EDT Wednesday...Overall, no significant changes to
forecast expectations. The Flash Flood Watch remains in place
across Essex County NY and central/southern VT through 03Z
Friday. Seeing a lull in the precipitation this evening, and
steady precipitation won`t redevelop until the pre-dawn hours
across the northern Adirondacks, and tomorrow morning across
central VT. The remnant low center is moving very slowly enewd
across n-central PA this evening. The interaction of this low
and leading band of sely 30kt 850mb flow with a deformation
zone extending ENEWD across the nrn Adirondacks into Central VT
will provide the primary forcing and focus for additional
precipitation. Other environmental factors supportive of
additional heavy rainfall include PW values near 2", low 70s
dewpoints, and warm cloud depths around 13kft across the above
mentioned areas through the day on Thursday. Instability looks
limited, but maintained a slight chance of thunderstorms in the
event surface-based destabilization can occur, especially across
s-central VT during Thursday morning/afternoon. The previous
discussion follows...
Previous Discussion: A flood watch is in effect for Essex
County, New York, and central and southern Vermont until 11 PM
Thursday where 2 to 3 inches and locally higher amounts of rain
will be common. Threat of heavy rainfall during the day on
Thursday has expanded further north with the most recent
forecast, with portions of northern Vermont now expected to
receive 1 to 2 inches of rainfall.
Today tropical moisture has been riding northward out ahead of
the main storm system with dew points in the 70 - 75 degree
range producing muggy conditions. A mix of high clouds and thin
stratus has limited convective activity this afternoon. Enough
instability is in place for scattered showers to drop some heavy
rainfall this evening, but the threat of thunder and lightning
remains low due to limited wind shear and poor lapse rates with
warm air aloft remaining overhead.
Visible satellite imagery this afternoon shows feeder bands
producing strong to severe thunderstorms off of the South Carolina
coast lifting into the circulation of the former tropical storm
spinning northeastward over western Pennsylvania. The latest model
consensus storm track takes the storm into central New York and
then eastward while its 700 millibar reflection passes right over
central Vermont. This forecast track and associated impacts on our
area has increased confidence in heavy rainfall. We`ll need to
monitor s-central VT for possible surface-based destabilization
given period of strong low-level shear and strongly curved
hodographs during the mid-late morning hours per HRRR and NAM
forecast profiles. At this time, appears instability is limited
northward into s-central VT. However, given shear profiles and
70s dewpoints, surface-based instability would bring the
potential for short-lived tornadoes, and that will be monitored
closely Thursday morning. Otherwise, briefly gusty winds will
be possible, especially in the western slopes of the Green
Mountains, with any convection. With the tropical conditions, we
should continue to see little range in temperatures over the
next 36 hours with temperatures mainly in the 70s, coolest when
steady rain is falling.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 350 PM EDT Wednesday...Friday should be a transition day as the
low pressure system associated with the remnants of Fred moves away
from the region through downeast Maine into the Canadian maritimes.
No cold air advection on the backside of Fred as under northerly
flow 850 temps actually increase to 17-18C. Ordinarily this would
put BTV around 90, but held it a little short based on lingering
cloud cover in the morning and wet ground, but still close to 90
with dewpoints in the upper 60s. Some instability around, but
expecting weak large scale subsidence to effectively cap anything so
just expecting some cumulus by afternoon. Should be partly cloudy to
clear Friday night under weak ridging surface and aloft.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 350 PM EDT Wednesday...Lots of possible solutions in the long
term as a good portion of the forecast hinges on what happens with
Henri. At this point, the office forecast track is off the east
coast with a large cone of possibilities from near eastern MA to
well offshore. The mostly likely solution right now is well
offshore with little impact to our forecast area. So it means some
weak surface and upper level features to deal with. A close upper
low/trof will move slowly across PA to southern New England through
Monday or Tuesday before finally we get back into the westerlies by
Wed. While we are on the east side of the upper low under deep
southerly flow we are pretty much guaranteed a return to warm and
very humid conditions with daily chances of showers with a few
thunderstorms right through the long term. High temps mainly in the
80s with lows in the 60s to around 70 here at BTV. There may be a
little cooler push of maritime air from the gulf of ME in
eastern/southern VT on Sunday/Monday if Henri can build the surface
ridge in the maritimes with an easterly flow but that is all
uncertain at this time. Stay tuned.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Through 00Z Thursday...Starting off with widespread VFR
conditions, however expecting rapid deterioration through the
evening and into tonight as the remnants of Tropical Storm Fred
move into the area. Precipitation will begin tonight as bands of
showers (some heavy) move through, becoming steadier moderate to
heavy rain during the morning Thursday. Ceilings will lower to
IFR/MVFR generally after 06Z, with some periodic showers and
areas of BR expected through 12Z. Rainfall becomes steady after
12Z, resulting in visibilities between 2SM and 4SM between 12Z
and 21Z. After 21Z, will see some improvement as the steadiest
rain exits to our east.
Winds will be of variable directions as the system moves
through, but will generally stay below 6 knots through 12Z.
After 12Z, will see easterly/northeasterly winds between 5 and
10 knots. There will be some weak low level wind shear over
southern and central Vermont after 12Z with easterly winds 20 to
30 knots expected between 1000 and 2000 ft AGL.
Outlook...
Thursday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Chance SHRA, Chance TSRA.
Saturday Night: VFR. Slight chance SHRA, Slight chance TSRA.
Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA, Slight
chance TSRA.
Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Monday: Mainly MVFR, with areas VFR possible. Chance SHRA, Slight
chance TSRA.
&&
.HYDROLOGY...
A Flash Flood Watch continues in effect for Essex County NY, as
well as central and southern VT through late Thursday evening.
Tropical environment (low 70s dewpoints, and PW values near 2")
associated with the remnants of Tropical Storm Fred is expected
to bring heavy rainfall on Thursday to central and southern
Vermont, and portions of the northern Adirondacks in NY. In
particular, southern portions of Essex County, New York has seen
as much as 3 inches of rain early Wednesday, which leads to an
elevated threat of flash flooding in that area as next round of
rainfall begins early Thursday morning. Current flash flood
guidance across the Flash Flood Watch area is about 2 to 4
inches over 6 hours and 1.5 to 2.5 inches over 3 hours. The
expected storm track suggests these areas may see sufficiently
heavy rain that could produce flash flooding.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Flash Flood Watch from 11 PM EDT this evening through Thursday
evening for VTZ008>012-018-019.
NY...Flash Flood Watch through Thursday evening for NYZ034-035.
&&
$$
SYNOPSIS...Duell
NEAR TERM...Banacos/Kutikoff
SHORT TERM...Sisson
LONG TERM...Sisson
AVIATION...Duell
HYDROLOGY...Kutikoff
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
610 PM MDT Wed Aug 18 2021
.UPDATE...
Issued at 554 PM MDT Wed Aug 18 2021
Scattered showers a few thunderstorms are occurring across SE
Wyoming into the Panhandle of Nebraska. Brief localized downpours
will be possible with this activity. Anticipate activity along and
east of I-25 to slowly diminish through late evening hours while
light to moderate showers persist across Carbon and Albany
Counties longer, being closer to the better dynamic lift from the
slowly approaching trough. Will continue to monitor the Mullen
Burn Scar through the evening and overnight as some training of
moderate rain showers will remain possible. Another round of
storms near the burn scar will occur thursday afternoon so will
again remain vigilant for any local flash flooding or debris flow
possibilities tomorrow. See below for more details and an updated
aviation discussion.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 300 PM MDT Wed Aug 18 2021
Forecast concerns deal with severe thunderstorms Thursday...then
strong winds Thursday night into Friday morning.
Currently...WPC surface analysis showing a cold front draped over
the central CWA from Chadron to Rawlins...westward to northern
Utah this afternoon. Main boundary though may be further west
across western Wyoming this afternoon. We are seeing increased
convection on radar moving north northeast out of western
Colorado. Latest IR imagery showing upper low currently along the
Idaho/Utah state line.
Short term guidance shows widespread coverage of showers and
storms across Carbon and Albany Counties this evening that backs
west after 06Z this evening as upper low tracks into eastern Utah.
Precip becomes widespread across entire CWA Thursday with upper
level divergence north of the low. Negatively tilted trough to our
southwest and west Thursday afternoon with a 90kt jet rounding the
base of the trough...moving into northern Colorado and southern
Wyoming during the afternoon.
Surface to 6km shear Thursday is prime for severe thunderstorms
with 45-50kts during the afternoon hours. Surface based CAPE 1000
to 1500 J/KG...so may not have enough instability to overcome the
shear. SPC does have a Slight Risk area identified over much of
the CWA for Thursday afternoon/evening. HRRR and NAMNEST simulated
radar both showing initial discreet supercells developing into
squall lines as they move into the Panhandle.
Strong gradient behind the trough passage Thursday night into
Friday morning. Local high wind height gradients showing Craig to
Casper height gradients surpass 60mtrs at 850/700mb after 06Z
through 15Z Friday. GFS 700mb winds increase to 60kts behind the
trough during this time. Decided to go ahead with a High WInd
Watch for that timeframe.
.LONG TERM...(Saturday through Wednesday)
Issued at 300 PM MDT Wed Aug 18 2021
Quieter weather ahead as we move into the early part of the weekend
with a ridge developing overhead bringing much drier conditions
across southeastern Wyoming and the Nebraska Panhandle. Temperatures
will remain slightly below normal on Saturday in the mid-70s and low
80s across the CWA. Next round of precipitation is expected to
return on Sunday with a minor upper level trough pushing eastward.
Confidence is fairly low at this time with any precipitation
chances, as moisture advection into the region remains low across
the whole domain and mostly confined to the western portions of the
Carbon County. Nevertheless, should see some gusty conditions from
this feature with greater than 25 knots wind gust west of the
Laramie Range. After the trough axis clears the CWA and continues
its eastward trek, the upper level pattern begins to trend towards a
zonal flow with brief periods of embedded shortwaves. Could see some
slight chances for showers and thunderstorms with these shortwave
energies Tuesday afternoon through Wednesday. However, the lack of
moisture advection will limit any strong storms at this time with
precipitable water values remaining low. High temperatures are
expected to make a rebound to near-normal and even above normal
early next week, with a few days spike to the low to mid-90s before
cooling back down on Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 554 PM MDT Wed Aug 18 2021
Scattered SHRA/TSRA this evening and also low MVFR to IFR
ceilings overnight followed by a potent round of TSRA Thursday
afternoon from CYS to DGW and east will be the main aviation
hazards next 24 hours. SHRA with some TSRA in SE WY and TSRA in
west NE is ongoing. TSRA activity win nebraska will slowly
diminish through 05Z tonight with KCDR and KBFF most likely near
TSRA activity. SHRA activity will continue neat KRWL and KLAR
through much of the overnight. Post cold front, and with north
winds, lower MVFR ceilings should develop across most terminals
but have lower confidence at KLAR and KRWL that should stay more
mixed. VFR will return by 18Z Thursday but MVFR could persist in
heavier rain showers. A more potent line of showers and storms is
likely tomorrow afternoon from 19Z through 06Z west to east from
KLAR to KAIA/KSNY. Storms will start near KLAR and form a line
north and progress east through the afternoon and evening hours.
Direct +TSRA will likely be needed in KCYS and points east on
subsequent updates.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Wed Aug 18 2021
Minimal fire weather conditions over the next several days as a
low pressure system tracks into the area from the west. Looking at
widespread wetting rains and much cooler temperatures. Even the
possibility of high elevation mountain snow. Strong winds expected
Thursday night into Friday morning behind the surface cold front
that is expected to move through the area during the day Thursday.
Stays cool and humid through the weekend before we begin to warm
up Monday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Watch from late Thursday night through Friday morning
for WYZ110-116.
High Wind Watch from late Thursday night through Friday morning
for WYZ106-117.
NE...None.
&&
$$
UPDATE...JSA
SHORT TERM...GCC
LONG TERM...MD
AVIATION...JSA
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
559 PM MDT Wed Aug 18 2021
.AVIATION...00Z TAF CYCLE
VFR conditions are expected across all the TAF sites with CIG
FEW060-110 SCT070-120 BKN110 SKC with VIS P6SM before 06z. The
winds will be southwesterly and generally above 12KTS with gust
up 25KT. Currently, there is a band of showers and thunderstorms
across the Socorro County with its tail end skirting through the
edge of the northern Sierra County that may impact KTCS. However,
it does appear to remain north of this terminal; thus, I have not
mentioned any thunderstorms in the TAF. I will continue to
monitor and amend if needed be should this move towards KTCS. For
tonight, conditions will settle and the CIG should become FEW-
SCT250 SKC. The winds will be between the west and southwest BLO
12KTS. For Thursday, quiet conditions are in store with no
significant changes expected. There will be no reduced visibility
across the runways.
&&
.PREV DISCUSSION...137 PM MDT Wed Aug 18 2021...
.SYNOPSIS...
Besides some isolated to widely scattered storms the next couple
of days, generally dry and warmer conditions will prevail. Some
monsoonal moisture will start to return Saturday over the east and
across the area for early next week. Temperatures will be warming
back to near or slightly above normal for most of the next week.
&&
.DISCUSSION...
.SHORT TERM...Tonight and Thursday
Current mid-level water vapor imagery overlaid with 500-mb RAP
analysis, shows a strong upper-level low over the Great Basin. The
trough axis is currently neutral, transitioning to negatively
tilted. As it does so, a shortwave trough over Baja California will
be the focus for shower/storm activity this afternoon. As the
shortwave trough lifts northeast into the desert SW, it will
continue sparking off showers/storms, greatest chance will be west
of the divide and in the Gila Mtns. Isolated storms can be
expected elsewhere. Conditions quiet down during the late evening
and overnight hours. Winds will become light and overnight low
temperatures will be right around the seasonal average.
The area will begin drying out heading into Thursday. The negatively
tilted trough will be over the northern Wasatch Range of UT/WY/ID
area. The trough axis will be off to the east, leaving the desert
SW under a large area of subsidence and west/southwest winds
aloft. The combination will give the area a dry day, compared to
what we have been experiencing. Most of the model guidance is
showing dew point temperatures falling back into the lower 50s
with precipitable water (PW) values right around an inch. The
outlier is with the ECMWF. This particular model still has dew
points right around 60 degrees, hence the slight PoPs for the
Sacs/Gila Mtns and far SE parts of Hudspeth County within the
grids. High temperatures for tomorrow will hover right around the
90 degree mark under mostly sunny skies.
&&
.LONG TERM...
Models remain consistent with the overall pattern for the next
week. Period starts Thursday night with plenty of dry air in place
with just enough moisture possibly lingering over far southeast
Hudspeth county. Otherwise mostly clear skies are expected and
overnight lows in the 60s to lower 70s. No change for Friday as
west to southwest flow continues over most of the area with that
same area in Hudspeth county having only precip chances.
Temperatures with the dry, westerly flow will warm into the lower
to mid 90s.
Going into the weekend, a typical monsoon pattern starts to setup
across the area with upper high over east TX/west LA and a
southeast flow out of the Gulf of Mexico gets established. Looks
like just far eastern areas will have enough moisture return
Saturday to see some storms, but going into Sunday and Monday,
chances spread west. The westward progression of the high may be
so far as to push the moisture plume almost out of the CWA early
next week. For now did keep in some 10-20 pops east, but if
current model forecast holds up, may have to take out mention of
thunderstorms east of the Rio Grande. Temperatures will remain
near to slightly above normal with mild overnight lows in the mid
60s to mid 70s.
&&
.FIRE WEATHER...
After an extended duration of very deep and plentiful monsoon
moisture across the fire zones, the region will begin transitioning
into a relatively short-lived drying and warming period starting
tomorrow. For today, the Gila and areas west of the Divide, shower
and storm chances continue. Lingering moisture and a sharp
disturbance tracking across eastern AZ and western NM will keep
good rain chances for the area. The rest of the region should see
reduced storm coverage with just a few isolated showers and
storms. Temperatures will be on the rise, but excessive heat is
not expected, with daily highs warming back to near seasonal
normals.
With the passage of a large trough axis on Thursday, winds will
shift to southwest and westerly to import drier air, as this flow
also flushes the monsoon moisture channel to our east. Through at
least Saturday, daily chances for rain and storms will be sharply
reduced, as temperatures warm and RH values gradually lower. Fire
weather concerns will continue to be low as neither of these
elements will even approach elevated or critical levels.
Sunday and into next week, high pressure builds across the gulf
states to our east. This will shift our winds back to southeast and
southerly to reestablish a monsoon pattern. These southerly winds
will tap moisture and pull it back over the region. You can expect
this will result in more afternoon and evening cloud development
with better rain and storm chances beginning Saturday.
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 70 91 72 94 / 20 0 0 0
Sierra Blanca 65 85 68 86 / 20 20 20 30
Las Cruces 65 88 64 92 / 10 0 0 0
Alamogordo 66 90 65 90 / 10 0 0 0
Cloudcroft 50 69 49 69 / 20 10 0 0
Truth or Consequences 65 90 66 91 / 30 0 0 0
Silver City 58 81 56 84 / 40 0 0 0
Deming 62 90 61 92 / 10 0 0 0
Lordsburg 63 87 62 88 / 30 0 0 0
West El Paso Metro 70 92 70 94 / 10 0 0 0
Dell City 67 92 65 91 / 10 0 0 10
Fort Hancock 69 93 68 93 / 20 10 20 20
Loma Linda 63 84 64 87 / 10 0 0 10
Fabens 69 92 70 94 / 10 0 0 0
Santa Teresa 66 91 65 92 / 10 0 0 0
White Sands HQ 68 90 68 93 / 10 0 0 0
Jornada Range 65 88 64 92 / 10 0 0 0
Hatch 64 91 66 94 / 20 0 0 0
Columbus 65 90 64 93 / 10 0 0 0
Orogrande 65 89 64 93 / 10 0 0 0
Mayhill 57 80 56 80 / 20 10 0 0
Mescalero 55 79 52 80 / 30 10 0 0
Timberon 54 76 51 78 / 20 10 0 0
Winston 53 83 51 84 / 40 10 0 0
Hillsboro 60 87 60 88 / 30 0 0 0
Spaceport 62 88 62 92 / 20 0 0 0
Lake Roberts 53 82 47 82 / 40 10 0 0
Hurley 58 83 58 86 / 30 0 0 0
Cliff 57 87 53 89 / 40 0 0 0
Mule Creek 59 82 51 86 / 40 0 0 0
Faywood 60 85 60 85 / 30 0 0 0
Animas 62 88 61 90 / 20 0 0 0
Hachita 62 88 61 90 / 20 0 0 0
Antelope Wells 62 88 60 89 / 10 0 0 0
Cloverdale 60 83 59 84 / 20 0 0 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
38-Rogers/26/36
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
708 PM CDT Wed Aug 18 2021
.AVIATION... /00Z TAFS/
Despite some weak dynamics aloft and surface dew points in the mid to
upper 70s along I-35 and at DRT, precipitation coverage has dropped
to near zero coverage around all the TAF sites. A weak boundary
collision 20 miles east of SSF will probably spawn a brief shower or
storm, but this is not enough reason to add any convective features
in the TAFs. The convection chances should remain near or below 20
percent through early Thursday, and the upper ridge becomes dominant
late in the TAF periods. Steady SE breezes should lead to more MVFR
cigs forming at thier typical diurnal times of 08Z to 16Z with the
onset at DRT being about 3 hours delayed to start the cigs period.
&&
.PREV DISCUSSION... /ISSUED 232 PM CDT Wed Aug 18 2021/
SHORT TERM (Tonight through Thursday Night)...
Area radars are showing light shower activity across the Hill
Country with stronger activity affecting areas east of Highway 183.
HiRes models are in good agreement on showing showers and
thunderstorms over the Hill Country and areas along and east of
Interstate 35 for the rest of this afternoon into the early evening
hours thanks to the passage of a mid level short wave. The HRRR and
RAP solutions keep shower and thunderstorm activity across the Hill
Country and over some areas between Highway 281 and I-35 through
late tonight as couple of fast moving perturbations move overhead.
Otherwise, a drying trend is expected across most locations after
midnight tonight and continuing through Thursday morning. An area to
watch tonight will be the northeast part of Mexico as ongoing storm
activity across the Serranias del Burro Mountains near the
international border could come closer to Del Rio area. For this
package, opted to go with a slight chance for showers and storms as
confidence is low.
For Thursday, expect cloudy skies over most places to begin the
morning commute. However, clouds will burn off by mid to late
morning, leading to mostly sunny skies for the afternoon period.
Highs are expected to reach the low to mid 90s across most areas and
closer to the 100 degree mark across the southwest. As far as
precipitation go, limited activity is anticipated as subtropical
ridge begins to take control of the area. However, there is a chance
for an upper level short wave to develop across the Big Bend and the
northern part of Mexico on Thursday afternoon. With southwest flow
aloft, some of the convection is expected to make it to the Val
Verde and Edwards Plateau areas. Once the daytime heating goes away,
expect for the showers and storms to diminish in the evening with a
rain-free period afterward.
LONG TERM (Friday through Wednesday)...
Two more days of rain and storm chances before Subtropical Ridging
takes a firm grasp over the CWA for the back half of the weekend.
Hurricane Grace is expected to move inland over eastern Mexico this
weekend, but the bulk of the tropical moisture will remain well to
our south. Nevertheless, some of that moisture may be pulled
northward to bring a chance for isolated to scattered showers and
thunderstorms on Friday/Saturday afternoon/evening for the Coastal
Plains and points generally along and east of I-35/I-37. PWATs have
backed off over the last few runs, and are now less than 2.0" for the
entire area on Friday afternoon through Saturday. Expect a slight
uptick in moisture both days, but chances remain quite low. Ridging
will begin its takeover on Sunday, sliding in from the east and
settling over north-central Texas. Expect temperatures to climb into
the 90s, but triple digits are likely to be less common, as recent
rainfall has helped to keep soil moisture above normal. This in turn
should keep temperatures down a degree or two from average through
the middle of next week. With the added moisture though, it will feel
like 105-110 and heat advisories may be needed early next week,
especially for areas east of I-35.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 78 95 77 95 76 / 20 10 0 10 0
Austin Bergstrom Intl Airport 77 95 76 95 75 / 20 10 0 10 0
New Braunfels Muni Airport 77 96 77 96 75 / 20 10 - 10 0
Burnet Muni Airport 77 93 75 93 75 / 30 10 - 10 0
Del Rio Intl Airport 78 98 78 98 78 / 20 20 - 10 -
Georgetown Muni Airport 77 94 76 94 75 / 20 10 0 10 0
Hondo Muni Airport 77 96 76 95 75 / 20 10 - 10 0
San Marcos Muni Airport 77 95 75 96 75 / 20 10 0 10 0
La Grange - Fayette Regional 79 95 78 96 78 / 20 20 0 20 0
San Antonio Intl Airport 77 95 77 95 77 / 20 10 - 10 0
Stinson Muni Airport 79 98 79 97 78 / 20 10 - 10 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Oaks
Long-Term...Treadway
Area Forecast Discussion
National Weather Service Grand Forks ND
956 PM CDT Wed Aug 18 2021
.UPDATE...
Issued at 955 PM CDT Wed Aug 18 2021
No changes since last update to thinking for tonight as evening
temperatures remain warm (upper 70s to lower 80s) and overnight
lows are still expected to remain around 70.
UPDATE Issued at 655 PM CDT Wed Aug 18 2021
Thinner smoke aloft allowed better daytime heating that previous
days, and early evening temps will start off around or higher than
90F. Front remains northwest and there should be enough low level
mixing to limit diurnal cooling tonight, so expect another mild
night (lows upper 60s to lower 70s). No major changes needed, only
minor near term adjustments.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 339 PM CDT Wed Aug 18 2021
An H5 ridge has moved just east of the FA this afternoon, with a
deep H5 trof continuing to dig into the western NOAM. A southwest
flow aloft pattern is steadily shifting eastward...into the
western Dakotas through this evening, and into eastern ND and
northwest MN late on Thursday. With deep convection expected into
eastern ND Thursday night through Friday.
For the rest of today... Expect fair skies and gusty south winds
through the remainder of the afternoon and early evening. Surface
low pressure now digging into central ND should stall this evening
and maintain a seasonably warm and moist southerly blayer flow
into the FA.
Overnight tonight... The 18z NAM guidance shows a 30kt H5 low-
level-jet over the area from 03 through 09z, but with little to no
near surface forcing indicated and marginal deep layer sheer,
mainly over central ND into far northeast ND. Have kept the
forecast dry tonight, in sticking with the consensus blend of the
18z HRRR and NAM features... though an isolated shower is
possible. Overnight lows will again settle into the upper 60s and
lower 70s, with the influence of that warm southerly flow.
Thursday and Thursday Night... The surface low should re-energize
into central ND through midafternoon, with increasing low level
flow and low level moist advection. Daytime highs should climb
into the 90s for most locations, and under generally fair skies
as smoke aloft is shunted northward. Mid to upper level clouds
will increase into the Devils Lake Basin, through the late
afternoon. A few showers may trigger west of the FA late in the
afternoon as well, but expect the main frontal push and deep
convection to coincide with the timing of an initial shortwave
trof, expected into eastern ND around midnight and across the FA
through Friday morning.
.LONG TERM...(Friday through Wednesday)
Issued at 339 PM CDT Wed Aug 18 2021
Cooler and wetter weather is likely from Fri onward as our upper
level flow turns southwesterly. Impacts would be due to the
influence of strong to severe thunderstorms later on Fri afternoon
into the evening in association with a strong cold front.
Ensemble members across the ECMWF, NAEFS, and GEFS model suites are
coming into very solid agreement regarding the passage of a rather
strong cold front later this week. Some timing differences exist,
but overall, the consensus brings a very good chance for showers and
thunderstorms into the CWA later Fri. CAPE and 0 to 6 km bulk shear
will be stout, with the former in the 1500 to 2500 J/Kg range, and
the latter between 45 and 55 knots. The focus for development will
be the pre-frontal trough, then the front itself Fri mid to late
afternoon. Following the convective activity Fri afternoon, showers
are expected to remain in the region in the post-frontal environment
through midday Sat.
A brief period of quiet weather should occur from Sat afternoon
through early Sun before another wave approaches the area. This
shortwave should be weaker than the Fri/Sat system, but will bring
another chance for showers and storms into the area starting late
Sun. Ensemble spread is somewhat large as we approach this point in
the forecast period, thus confidence is low, especially regarding
the timing. Precipitation chances remain spread across the forecast
area through Wed in association with another upper low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 655 PM CDT Wed Aug 18 2021
VFR conditions should prevail through the TAF period, with gusty
southerly winds diminishing some during the nighttime period
tonight before increasing again Thursday (after sunrise). While
not as thick, smoke lingers aloft generally above 15000 FT AGL.
Surface low pressure and an associated front slides southeast
Thursday morning and winds shift to the west at KDVL and decrease.
Eventually this front will bring increasing shower and
thunderstorm chances, however best chances remain late Thursday
night into Friday.
&&
.FIRE WEATHER...
Updated at 339 PM CDT Wed Aug 18 2021
Expect south to southeast winds gusting at 25 to 30 mph along and
west of the Red River corridor, and at 15 to 25 mph into northwest
MN throughout the afternoon and early evening. Winds will settle
into a light southerly flow overnight and pick up to similar level
on Thursday afternoon.
Another warm day is on tap for Thursday, with highs reaching into
the lower 90s in many locations. The exception being the Devils Lake
Basin, where increasing clouds ahead of an approaching cold front
will limit daytime heating. The main rain event should move into and
across the area from Thursday evening through Friday, with a
widespread wetting to soaking rain expected.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...Gust
LONG TERM...WJB
AVIATION...DJR
FIRE WEATHER...Gust
Area Forecast Discussion
National Weather Service Flagstaff AZ
832 PM MST Wed Aug 18 2021
.SYNOPSIS...Showers and thunderstorms will continue to gradually
diminish through the overnight hours. Drier conditions are
forecast to develop Thursday, and will continue through the
weekend. Cooler temperatures are also expected through the rest of
the week.
&&
.DISCUSSION...Convection from earlier today is slowly coming to an
end across much of northern Arizona this evening. Residual water
from very heavy rainfall earlier this afternoon and evening is
still flowing through creeks and washes into the larger river
systems so avoid these areas overnight. Hi-res guidance continues
to indicate the potential for additional storm development across
northwest Coconino County overnight, but the rest of the area
should be mainly dry.
Drier air will push into the region on Thursday as a trough passes
to our north. Outside of a lingering storm threat along the Utah-
Arizona border, expect dry conditions. The pressure gradient will
tighten in response to the trough with breezy southwest winds
developing in the afternoon as a result.
Minor updates were made to the forecast this evening to account
for radar trends. Otherwise, everything is on track.
&&
.PREV DISCUSSION /305 PM MST/...A flash flood watch remains in
effect for Gila, Yavapai, and Coconino County until 11pm MST.
Numerous showers and thunderstorms will continue to develop across
northern Arizona through the late afternoon and early evening
hours. So far the main hazard has been flash flooding, with no
reports of hail or damaging winds received so far.
The latest HRRR indicates lingering thunderstorm activity
areawide through at least 8pm MST this evening, with mainly dry
conditions developing from south to north through the overnight
hours as drier air moves in ahead of an upper trough digging into
the Idaho/Nevada/Utah region.
By Thursday, the aforementioned trough should be centered east of
the Great Salt Lake, resulting in mostly dry and breezy conditions
across central and northern Arizona. Low chances for afternoon
thunderstorms will exist near the AZ/UT border where the greatest
upper level support will reside.
By Friday, dry conditions are forecast areawide as a baggy trough
sets up off the California coast producing dry southwesterly flow
aloft. This feature should keep dry conditions over northern
Arizona through the weekend, with a gradual warming trend.
Monday through Wednesday, another monsoonal pattern begins to
develop. Low chances for thunderstorms will develop each afternoon
along the higher terrain, with a gradual increase in afternoon
thunderstorm chances through mid-week.
&&
.AVIATION...For the 06Z package...Shower and thunderstorm coverage
will continue to gradually diminish overnight. TEMPO MVFR/IFR
conditions will remain possible in stronger storms especially west
of KGCN. Much drier conditions are then forecast to develop Thursday.
Breezy southwesterly winds are forecast by Thursday afternoon.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Much drier conditions are forecast over northern
Arizona Thursday and Friday. Breezy southwesterly winds will
develop Thursday afternoon, with lower wind speeds expected
Friday.
Saturday through Monday...Dry weather will continue through the
weekend. By Monday, low chances for afternoon thunderstorms will
return to the forecast for the Apache-Sitgreaves National Forest.
Dry conditions are expected elsewhere.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch until 11 PM
MST this evening FOR AZZ004>009-012-015-016-018-037-038.
&&
$$
PUBLIC...TPS/TM
AVIATION...TPS
FIRE WEATHER...TM
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Green Bay WI
1027 PM CDT Wed Aug 18 2021
Updated aviation portion for 06Z TAF issuance
.SYNOPSIS...
Issued at 325 AM CDT Wed Aug 18 2021
Generally quiet late-summer weather will continue for the
remainder of the work week as temperatures and humidities
continue to edge upward.
The main westerlies will amplify a bit more the next couple days
as a seasonably strong trough finishes deepening into the
Intermountain West, and downstream ridging consolidates/sharpens
over the upper Mississippi Valley. The longwave trough position
will initially remain out west even as the bulk of the energy lifts
out toward James Bay this weekend. The remnants of the trough
will eventually become progressive next week, likely reaching the
area near the end of the forecast period.
Temperatures will top out about 8-12F degrees above normal the
next few days, drop back a bit during the weekend, then remain
at least somewhat close to normal next week.
There is little chance for widespread/significant precipitation
the next few days, with the first substantial chance being tied to
the passage of a cold front this weekend. A better opportunity
for precipitation may occur if a frontal boundary lingers near
the area early next week as the remnants of the upper trough
approach from the west. But thats pretty far into the forecast and
highly uncertain, so the most likely situation is that we`ll end
up with AOB normal precip amounts for the period.
&&
.SHORT TERM...Today...Tonight...and Thursday
Issued at 325 AM CDT Wed Aug 18 2021
Quiet late-summer weather will continue through the short-term
portion of the forecast. Once again, bumped up the NBM mid-
day/early afternoon skycon after reviewing yesterday`s vis stlt
loop. In addition, used the HRRR smoke forecast to reflect the
smoke layer aloft. The smoke aloft should affect mainly the north
and far west today, and then get driven down into the northeast
part of the forecast area Thursday.
Some of the guidance continued to suggest isold/widely sct SHRA
could develop in the lake breeze convergence zone this afternoon
and again tomorrow. That area may get brushed with a little QG
forcing for ascent early today, but the forcing will probably have
pulled away to the NE before the atmosphere destabilizes and the
low-level convergence fully sets up. And there will be weak QG
support for subsidence on Thursday. So while a few sprinkles or
showers can`t be ruled out, the support for them just didn`t seem
sufficient to warrant adding them to the forecast. We`re in a
pattern that is changing very slowly, and the nearest air mass
showers that developed yesterday were south of Kankakee IL, which
is pretty far to our south.
Stayed close to a broad-based blend of recent top performing
guidance products for high temperatures. Opted to lean toward some
of the cooler guidance for mins based on readings the past couple
nights.
.LONG TERM...Thursday Night Through Tuesday
Issued at 325 AM CDT Wed Aug 18 2021
The latest NWP models indicate the approaching low pressure system
headed for the western Great Lakes region will be delayed a bit
from previous forecasts as the low develops across the Red River
Valley on Friday with a fairly dry airmass in the mid and upper
levels of the atmosphere along with a substantial capping
inversion between 700 and 750 mb. Therefore, will remove POPs on
Friday as it appears the best chance for rain will be late Friday
night into Saturday with the arrival of the cold front. Showers
and thunderstorms are expected as the cold front tracks through
the region; however, the severe and heavy rain potential appear
low as the cold front tracks through the area. Instability is not
all that high, generally less than 1000 J/kg of MLCAPE, upper
level dynamics are not all that impressive as the main mid level
trough and shortwave track through Canada, along with the fast
movement of the front, which should help limit flooding potential.
The passage of the front will bring an end to the hot and humid
weather across northeast Wisconsin late in the weekend and into
early next week as temperatures return to near normal levels for
this time of year. A few mid level disturbances embedded in the
zonal flow will bring the chance for showers and thunderstorms at
times through early next week as the track through the region.
Given the weak nature of these disturbances, exact timing of wet
and dry periods is difficult to determine at this time.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1022 PM CDT Wed Aug 18 2021
Clear skies and light winds will result in another night of patchy
ground fog (with mainly MVFR/IFR vsbys) over much of the forecast
area. The fog has started a bit earlier in north central WI than
previous nights, so will adjust the timing for the RHI TAF. Otherwise,
have followed the trends of the past few nights for the timing of
TEMPO groups and VSBYs at the other TAF sites.
Scattered Cumulus clouds will develop again by late morning Thursday,
then dissipate by sunset.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Kurimski
AVIATION.......Kieckbusch
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1010 PM EDT Wed Aug 18 2021
.SYNOPSIS...
Warm and humid conditions will continue through the remainder
of the week. The remnants of Tropical Storm Fred will move into
the area on Thursday bringing increased chances for heavy
rainfall, which may result in areas of flooding. Drier weather
is expected to return on Friday, although the humidity will
remain elevated. Tropical Storm Henri may approach New England
early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Update...Adjusted PoP to reflect latest radar trends and model
forecasts. We are definitely going to see a break from
significant shower activity and will await the remnants of Fred
to move in after sunrise for likely PoP to return.
Previous discussion...An upper level trough is currently
crossing through southern Quebec as a semi-stationary front is
draped across southern New England and NY State. Temperatures
this afternoon have warmed into the lower 80s while surface
dewpoints have climbed into the lower 70s. This has allowed for
some convective instability to develop over the region with the
latest SPC mesoanalysis indicating that between 1500-2000 J/KG
of SBCAPE is located across portions of central NH and
southwestern ME with mid-level lapse rates of around 5C/KM. This
aligns rather nicely with the 18Z KGYX sounding, which
indicated SBCAPE of around 2100 J/KG with a DCAPE of nearly 500
J/KG. There is also around 25 kts of effective bulk shear
located near the International Border, but this region of higher
shear coincides poorly with the highest CAPE. The latest few
high resolution forecast guidance runs such as the HRRR indicate
that a few strong thunderstorms may develop through early this
evening, especially from roughly the International Border south
through the Capitol Region of ME. While am not expecting
widespread severe weather, there will be a non-zero threat for a
locally strong to severe thunderstorm through the remainder of
the afternoon and evening with locally strong winds the primary
concern.
Later tonight the threat for strong thunderstorms will gradually
diminish but there could be few lingering showers and isolated
rumbles of thunder overnight as we remain very warm and humid.
There will also likely be areas of fog overnight, especially
across the valleys and while widespread dense fog is not
currently expected, some localized dense fog cannot be ruled
out. ALl eyes will then turn towards the remnants of once
Tropical Storm Fred, which will begin to approach western NH
towards daybreak on Thursday.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The remnants of once Tropical Storm Fred will begin to move into
our area early Thursday morning bringing areas of heavy rainfall
to the region through Thursday evening. Rain will begin first
across southwestern NH before quickly advancing northeastward
into western ME through the mid to late morning hours. Forecast
PWATS of around 2.00" combined with upshear corfidi vectors of
between 10-15kts will cause concern for heavy rainfall, which
may result in areas of flash flooding. A Flash Flood Watch was
therefore issued for central and southern NH as well as for
portions of southwestern ME from 8am Thursday through 2am
Friday. There still remains some differences in model guidance
as to exact rainfall amounts and the placement of the heaviest
rain axis but generally expecting between 1 to 3 inches of rain
across the southern two thirds of NH and southwestern ME with
lighter amounts towards the International Border and along the
Mid-Coast. The primary areas of concern for flooding issues
would be across the White Mountains where upslope flow may
result in enhanced rainfall rates as well as across the hilly
and urban areas of southwestern NH. Lastly, as with most
tropical or post tropical systems there will be quite a bit of
low to mid level helicity, which will introduce the possibility
for a few rotating cells. Rain will gradually end from
southwest to northeast tomorrow evening with showers becoming
more isolated in nature overnight.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Warm Start, with Henri Poised to Track North...
Remaining showers associated from Freds remnants should be
waning come Friday morning. Only expect a few sprinkles across
mostly the ME coastal plain and SE NH, with the ECMWF the
slowest of among the GFS and GEM trio. The NAM dries out
quickly, and have edged toward this solution. Friday will also
be the warmest day of the foreseeable forecast as a backdoor
cold front approaches from the north ahead of high pres. Forcing
and instability ahead of the fronts passage may result in a
few showers or storms developing late in the day across the
western ME mtns and northern NH. Elevated instability remains
for much of the area south and west, allowing the chance for
showers or thunder into the overnight hours. With low shear and
moderate PWAT values overhead, can expect some of these to
contain decent downpours.
Saturday, the cold front will continue to creep south, focusing
the chance for showers or thunder across NH. Daytime highs cool
the greatest across southern Maine, rising into the mid 70s vs
low to mid 80s on Fri.
NHC forecasts Henri to hook north and interact with the
dropping cold front, with added influence by a building ridge
over Atlantic Canada. With guidance still displaying a wide
envelop of solutions, there remains larger than usual
uncertainty. While some guidance makes waves with potential
landfall locations, waves and swell may be the more confident
part of coastal ME/NHs forecast. The potential exists for
long period swell and increasing wave heights into early next
week that may result in high surf conditions.
Henris track and interaction with the front/ridge will be
crucial in its track and precip chances across New England. With
lower than average confidence, have mirrored similar chances of
rain through Mon and Tues of next week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Short Term...Fog is expected tonight, especially across valley
terminals which will likely lead to MVFR/IFR conditions for a
few hours. Fog will gradually lift by around 12Z Thursday but
MVFR ceilings may linger for much of the day as RA begins to
move in from southwest to northeast. Additional valley fog is
possible Thursday night as RA gradually ends from southwest to
northeast during the evening.
Long Term...MVFR conditions improve during the afternoon, but
may return overnight as Fred`s remnants pull out to the Gulf of
Maine. Showers and thunderstorms will be possible overnight,
mainly in the western mtns, potentially making it to KHIE and
KAUG. MVFR/IFR conditions are possible later into the weekend.
&&
.MARINE...
Short Term...Winds and seas to remain below SCA through
Thursday. Southeast winds will increase Thursday night and gust
to around 20-25 kts as seas build to 3-4 feet.
Long Term...Conditions are expected to be below SCA through Sat
night. Waves and period along the outer coastal waters begin to
increase Sun afternoon in association with Henri moving north,
with SCA conditions possible Sun night. Long period swell and
wave heights will build, but there remains uncertainty in
Henris path. This track will play a larger role in where
stronger winds may build, whether along the coastal waters or in
the Gulf of Maine/Open Atlantic. Moisture and moderated temps
may keep patchy fog on the waters through Saturday.
&&
.HYDROLOGY...
The remnants of once Tropical Storm Fred will
interact with a warm and humid airmass and result in areas of
heavy rainfall on Thursday. Rainfall amounts of 1 to 3 inches are
expected with locally higher amounts possible where storms move
over the same location multiple times as well as across the
upslope regions of the White Mountains. There will be the
potential for flash flooding, especially across the White
Mountains as well as in the hilly and urban areas of
southwestern NH.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flash Flood Watch from 8 AM EDT Thursday through late Thursday
night for MEZ012-018>020-033.
NH...Flash Flood Watch from 8 AM EDT Thursday through late Thursday
night for NHZ003>013-015.
MARINE...None.
&&
$$
NEAR TERM...Legro
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
910 PM EDT Wed Aug 18 2021
.SYNOPSIS...
A developing frontal boundary will be the focus for showers and
thunderstorms tonight and Thursday. The threat for showers and
thunderstorms is expected to diminish Friday under weak high
pressure. A couple of disturbances will interact with an
unstable airmass to keep the chance for precipitation through
the weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Low-end PoPs have been continued through the overnight hours
for most of the ILN CWA, as widely isolated showers continue to
develop here and there -- with recent HRRR runs suggesting this
may continue. Otherwise, there has been no appreciable change to
the forecast. The main concern heading into the morning hours is
with the potential for some heavy rain to set up south of the
Ohio River after 10Z. The last few hours of HRRR/RAP runs have
been focusing this activity just south of the ILN CWA, which
means that the previous forecast -- a low probability of heavy
rain and minor flooding in the southern ILN counties -- remains
valid. Obviously, it will be important to monitor trends and see
if this activity will end up setting up any further to the
north.
No changes to the previous forecast on fog potential or
temperatures. Given that dewpoints are still generally in the
lower 70s, and that winds are very light, some patchy dense fog
is not out of the question if any persistent clear spots develop
in the cloud cover.
Previous discussion >
Scattered showers forming in a humid and unstable airmass are
forecast to persist into this evening. We may experience a few
rumbles of thunder, though the chance for organized convection
appears to be limited early tonight by a lack of strong
forcing.
After this initial precip diminishes with loss of daytime
heating, models indicate an uptick in convection later tonight
due to a band of frontogenetic convergence developing near the
Ohio River in conjunction with a weak but deepening upper
trough. Showers and thunderstorms will become likely in
southwest counties in the early morning hours with chance pops
farther north, and some heavy downpours will be possible. Slow
moving cells and PWAT ~1.9 inches could lead to localized
flooding as noted in the HWO. Look for temperatures to fall to
around 70 by 6 am, and patchy fog should develop as well as
temps fall close to dewpoints.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Band of showers/storms is forecast to spread northeast
Thursday, while staying mainly across the southern portion of
the FA. Localized high water will continue to be a threat into
Thursday afternoon until frontogenetic forcing and the upper
trough translate east. A decreasing trend in precipitation
should be observed Thursday evening through Thursday night.
Highs temperatures are expected to reach the low 80s in most
locations, though southeastern sites could be limited to the
upper 70s by precip and clouds. Lows Thursday night should drop
to the mid and upper 60s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Friday, low pressure will deepen across the Great Lakes region,
developing into a weak closed mid-level low Friday night. This low
will linger and start to weaken on Saturday as TS Henri spins over
the Atlantic and halts the normal flow progression. By the end of
the weekend, the next frontal system moves east across the region
and ushers the initial low out of the forecast area. These
disturbances will govern the weather across the region for the
beginning of the period. Chance for mainly diurnally driven showers
and thunderstorms are expected Friday and Saturday afternoon before
the first low is ushered out, along with near normal temperatures.
With the next trough axis approaching from the west Saturday night,
kept pops higher than model guidance heading into Sunday. Pops stick
around through Sunday with the passage of a cold front, then a
drying trend is expected early next week as the models indicate
better ridging over the Ohio Valley. Ridging will help support
temperatures a bit above normal. Disturbances may start to impact
the area Tuesday into Wednesday, but confidence is low on presence
and timing this far out.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR conditions will start the TAF period, with just a few
showers still floating around the area tonight, and unlikely to
create any additional restrictions to aviation conditions.
Early tomorrow morning, chances for rain will begin to increase
again, particularly for KCVG/KLUK/KILN. It appears very likely
that a period of rain will occur at each of these airports,
though the exact timing is still somewhat in question. The most
likely timing has been included with an -SHRA period in the
TAFs, with VCSH at other times, and for the other TAF sites
where rain is not quite as certain to occur. Although not
explicitly in the TAFs, some brief periods of heavy rain may be
possible, which could lead to IFR conditions.
MVFR ceilings are also expected for a few hours at all TAF
sites, though at this point it appears IFR ceilings are not
likely to occur. There is also a chance of some fog in the
early morning, but this has been limited in the forecast to the
MVFR category, either in a prevailing group or a TEMPO group.
Winds will remain light through the forecast period.
OUTLOOK...Thunderstorms are possible on Friday, Saturday, and
Sunday, mainly in the afternoon.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/Hatzos
SHORT TERM...Coniglio
LONG TERM...Cornelissen/BPP
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Lake Charles LA
1000 PM CDT Wed Aug 18 2021
.UPDATE...
Evening update.
&&
.DISCUSSION...
Showers and thunderstorms from earlier in the day have moved
northward out of the area and mostly dissipated. Partly cloudy to
mostly cloudy skies will be expected for the first part of the
overnight hours with the possibility of showers and thunderstorms
forming in the early morning hours for southern areas. This
activity will be expected to move northward as the morning
progresses. Although models show patchy fog for parts of Central
LA and there will be light onshore flow to support it, the
additional cloud cover overnight and possible storm activity in
the morning may prevent fog from forming.
Shower and thunderstorm activity in the morning (with the
additional cloud cover) may help to inhibit storm development
later in the day. Regardless, scattered thunderstorms will be
expected tomorrow with the may concern being the timing and
magnitude of the storm formation in the morning hours. The latest
run of the HRRR (01Z) shows significant development starting
around 07-08Z and focusing primarily on the western side of our
area. This aligns fairly well with the current forecast.
Therefore, no changes were made.
55
&&
.PREV DISCUSSION... /issued 705 PM CDT Wed Aug 18 2021/
DISCUSSION...
00Z TAFS
AVIATION...
The vast majority of convection has lifted north of the region
this evening. However, a weak upper level trof extending into the
region may provide enough support to maintain scattered showers
and thunderstorms over the coastal waters overnight which will
have the potential to move onshore impacting the coastal
terminals through the night. This idea is depicted in a few of the
high resolution short range models so felt it prudent to maintain
the included VCTS at the coastal terminals early Thursday
morning. By late morning, the more typical, diurnally driven,
convection will become more widespread.
Outside of convection, VFR conditions will prevail. High pressure
centered over the northeastern gulf of Mexico will maintain light
southerly winds through the taf period.
Jones
PREV DISCUSSION... /issued 405 PM CDT Wed Aug 18 2021/
SYNOPSIS...
The region remains beneath southwesterly flow aloft between a
trough over the southern plains and high pres off the east coast
ridging acrs the northern Gulf per the latest UA analysis and WV
imagery. Weak disturbances emanating through the southwesterly
flow were supporting a little better coverage of showers and
storms this aftn, especially acrs SE TX where deeper moisture is
noted. Precip water on the 12Z KLCH sounding was 2.25 inches, and
recent LAPS analysis and GOES TPW indicate that PWATS remain
considerably high, from around 2 inches acrs S Cntl LA to 2.3+
inches acrs SE TX. These values are well abv average for this time
of year per SPC sounding climatology, near and even exceeding the
90th percentile acrs much of the area.
Southerly winds around the western side of sfc high pres are
keeping moisture entrenched in the lower levels, with dewpoints in
the middle and upper 70s. Outside of any cooling effects of
showers, temperatures are in the lower 90s and, combined with the
higher dewpoints, heat index values are running mostly between
100 and 108 degrees.
24
SHORT TERM [Tonight through Friday night]...
Showers and storms should diminish this evening with the loss of
daytime heating. However, upper level support from the nearby
trough will keep at least a low chc for convection over parts of
the area tonight, especially along and south of I-10 as nocturnal
showers and storms develop over the nearshore waters and spread
inland. Showers and storms will again begin to increase in
coverage by midmorning Thursday as convective temps in the
middle 80s are met. The airmass over the region will again be
characterized by deep moisture and instability, with PWATs well
above normal (ranging from 2 to nearly 2.4 inches), and
potentially approaching the max moving average per climo. This
will allow for efficient rain processes, resulting in heavy
rainfall and intense rainfall rates at times in some of the
storms.
The last of the upper disturbances associated with the trough
should pass the region on Thursday, with the trough lifting
northeast Thursday night into Friday, as the upper ridge acrs
the northern Gulf builds further west. This will be accompanied by
lower PWATs, and consequently lower rain chcs for the end of the
week. Unfortunately, as rain chcs decrease, temperatures will warm
back into the middle 90s during the day Friday.
On Friday, there could be some coastal effects from what is likely
to be Hurricane Grace passing well south of the region, over the
Bay of Campeche. Thanks to an extended fetch of southerly winds,
tides levels are expected to be elevated, and fcst tide heights
could reach 1.5 feet mean higher high water (MHHW) during
astronomical high tide times. This is about 1 to 1 1/2 feet abv
typical predicted values, and could result in minor flooding along
portions of the SE TX and SW LA coast.
24
LONG TERM [Saturday through Wednesday]...
By the beginning of the weekend, the upper level ridge over the Gulf
of Mexico will be right over the region. Afternoon PoPs over the
weekend will be limited because of the ridge, however sufficient low
level moisture keeps the PoPs in the 10-30% range.
Afternoon max temperatures will gradually increase over the extended
period, with a few areas reaching the triple digits late this
weekend and into early next week. Afternoon heat indices will be in
the 100 - 115 degree range. Some areas will meet the criteria
necessary for the issuance of a Heat Advisory so please be safe
while working outdoors.
On Monday and into early next week the upper level ridge will
drift off to our west allowing for higher PoPs for areas along the
coast and the Atchafalaya Basin. Unfortunately we are still
looking at high heat indices in the same range mentioned
previously.
Stigger/87
MARINE...
Light to moderate onshore flow will prevail into the weekend as
sfc high pres builds acrs the northern Gulf of Mexico. The
combination of an upper level trough over TX and an abnormally
moist airmass will result in increasing showers and tstms over the
coastal waters this evening and overnight. Locally higher winds
and seas and occasional cloud to water lightning can be expected
near the storms.
A high pres ridge aloft building west acrs the Gulf coast will
help steer what is expected to be Hurricane Grace westward into
the southern Gulf/Bay of Campeche Thursday night into Friday.
While the main impacts of Grace are expected to remain well south
of the area, the increasing southerly fetch during this time will
bring increasing swells, which will produce elevated wave heights
especially over the coastal waters beyond 20 NM. Exercise caution
or advisory flags may be required at times, especially from Friday
into early Saturday. Conditions should begin to improve by Sunday.
24
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 77 92 76 95 / 50 70 20 30
LCH 78 91 78 92 / 30 50 10 30
LFT 78 93 76 94 / 30 70 10 30
BPT 77 91 77 93 / 50 50 10 30
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
734 PM EDT Wed Aug 18 2021
.SHORT TERM...(This evening through Thursday)
Issued at 306 PM EDT WED AUG 18 2021
The short term period is overwhelmingly quiet with surface ridging
dominating our weather and resulting in mostly clear skies and light
southerly winds. A widespread field of diurnal cumulus developed
this afternoon, especially across the west. However, a capping
inversion and dry air aloft is limiting vertical development with
cumulus likely to clear quickly after sunset.
Clear skies and light winds should result in good radiational
cooling across the interior tonight. The same general pattern was in
place last night and areas of dense fog developed across the east
this morning. That seems plausible again tonight so I put widespread
mentions of patchy fog near the Lake MI shoreline through Thursday
morning. Haze is ubiquitous across the CWA this afternoon and HRRR
smoke guidance indicates that will persist throughout the short term
period. The good news is near surface smoke is minimal.
Thursday`s weather pattern won`t be much different than today, but
model soundings are less excited about the potential for diurnal
cumulus. If that`s the case then high temperatures may be a degree
or two warmer than today. Southerly winds off Lake MI should hold
temperatures down near those lakeshores. Similar to this afternoon,
a lake breeze may push onshore around the Keweenaw Bay to take the
edge off the heat of the day.
.LONG TERM...(Thursday night through Wednesday)
Issued at 351 PM EDT WED AUG 18 2021
Models indicate the amplified mid-upper level pattern breaking down
by late week with a progressive, quasi-zonal flow setting up over
the northern CONUS and Upper Great Lakes region late this weekend
into the middle part of next week. As a result, dry weather on
Friday will give way to a series of shortwaves which will bring
periodic chances for light showers this weekend into the middle of
next week. With generally limited moisture for these shortwaves to
tap into, expect only light rainfall. At the same time, temperatures
will trend from well above normal on Friday to normal or slightly
above normal late this weekend into the middle of next week.
Beginning Thu night into Fri, with the amplified H500 ridge (587-588
dam) axis over the area, dry and very warm conditions are expected.
Look for min temps generally in the lower to mid 60s Thu night and
inland max temps Friday well into the 80s and even low 90s as 850 mb
temps of 18-20C mix to the sfc during the day. Onshore southerly
flow will keep max temps a bit cooler near the Lake Michigan shore,
in the mid to upper 70s.
Saturday, central/northern Plains shortwave approaches late Fri
night and then moves across the cwa along with its associated cold
front on Saturday. Although PWATs approach 1.5 to 2 inches ahead of
the front, models indicate the best dynamics staying well north into
Canada so model qpf fields depict more of a broken line of showers
moving across the cwa Saturday into Saturday evening. With CAPE
values approaching 1000 j/kg there should be some thunderstorms as
well, although expect better instability and shear for strong to
severe storms to stay southwest or west of the area closer to the
track of the vort max with the shortwave. Under more clouds, expect
max temps generally in the lower to mid 80s.
Saturday night into Sunday, ended showers a bit quicker than the NBM
blend over the eastern counties of the U.P late Sat night into
Sunday as sfc high pressure looks like it builds in quickly from the
west behind the shortwave/cold front. Definitely, cooler and less
humid behind the front Sat night into Sunday with more comfortable
conditions. Max temps will fall back closer to seasonal normals with
highs generally in the mid 70s most locations.
Models show reasonable agreement with another shortwave and frontal
system moving in late Sunday night into Monday and then perhaps a
stronger shortwave/cold front moving in by midweek (Wed-Thu time
frame). Limited moisture will probably only yield scattered light
showers for the early week system, but stronger dynamics could yield
more widespread showers with the midweek system. Cooler h850 temps
in the single digits Celsius in wake of the midweek system could
even bring some scattered lake effect rain showers to some locations
near Lake Superior late next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 728 PM EDT WED AUG 18 2021
VFR conditions will continue to prevail at all three terminals as
high pressure remains in control. Winds will generally have a
southerly component through the TAF period, with some variability,
particularly overnight at KCMX and then again tomorrow afternoon
near the lakeshores with the formation of the lake breeze. Expect
diurnally-driven fair wx CU to pop back up tomorrow as well.
Although some smoke has returned to the region, it remains on the
light side and aloft, with no impacts to visbys at the surface.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 306 PM EDT WED AUG 18 2021
Surface high pressure persists through Friday with winds of 15 knots
or less across the lake. Southerly winds with gusts around 20-25
knots possible Friday night into Saturday ahead of an approaching
cold front. A cold front moves through Saturday night with winds
becoming northwesterly and gusting to around 20 knots behind the
front. Winds weaken below 20 kts on Sunday and stay light through
the end of the extended period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...EK
LONG TERM...Voss
AVIATION...lg
MARINE...EK
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
946 PM EDT Wed Aug 18 2021
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
A line of showers and storms is currently approaching out of
middle TN. The HRRR continues to suggest that this line weakens
as it moves into our area. However, the southern Cumberland
Plateau and southern TN valley may see a strong storm or two
before the storms fall apart. Then, expect scattered showers and
a few storms to move further eastward into the central/southern
TN Valley, approaching I-75. This is where I have POPs dropping
off, east of 75. This may be to hopeful though as the HRRR
suggests scattered showers push further east of 75. Will monitor
the trends and adjust as needed.
Otherwise, forecast on track tonight with no changes. Will send
out new zones for POP adjustment.
SR
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions for all sites until early tomorrow morning when
MVFR fog is possible. Then, MVFR conditions expected through much
of the day at all sites as scattered showers and storms move
through the area. Flight conditions may briefly drop below MVFR if
a heavy shower or storm passes directly over a terminal.
There is a low chance that a line of showers and storms could
move across CHA around midnight but not enough confidence to go
more than VCTS at this time.
SR
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 73 85 71 86 71 / 50 70 40 70 40
Knoxville McGhee Tyson Airport, TN 71 83 70 86 70 / 30 70 50 60 30
Oak Ridge, TN 71 81 68 86 69 / 40 70 50 60 30
Tri Cities Airport, TN 67 83 68 84 66 / 20 70 50 70 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
858 PM PDT Wed Aug 18 2021
.SYNOPSIS...Northerly, offshore winds will increase later tonight
over dry conditions in the North Bay Mountains of Napa County.
Smoke and haze continue to move southward from Northern California
as fire concerns remain high around the state. Temperatures will
remain seasonable into the weekend.
&&
.DISCUSSION...as of 08:56 PM PDT Wednesday...The Cache Fire is
starting to dwindle on satellite imagery, but in reality is only 20
percent contained at this hour. Meanwhile, another a new fire has
popped up on satellite in Kern county being called the French Fire.
As if it needs to be said, conditions around California are
incredibly dry where fires can be easily started and those burning
like the Dixie and Caldor are burning with extreme growth.
While the coastal areas have been helped by the marine layer,
conditions at interior and higher elevations of the Bay Area are
just as dry. Winds today have been mostly around 20 mph keeping the
daytime risk fairly low. Dry conditions continue into tonight as
northerly winds will increase tonight once again for a second push
from the upper level low. It has been forecasted that it would
increase again tonight over the North Bay Mountains, but with weaker
conditions than last night. Recent HRRR and NAM runs, keep that
trend continuing into tonight. Models are continually keeping
stronger gusts over 30 mph in Lake, Colusa, and Yolo counties,
keeping Napa in the 20 to 25 mph, with localized 30 mph gusts for a
short duration. While counties to the north have red flag warnings,
Napa, Sonoma, and Contra Costa Counties were kept out of a red flag
on account of the short duration of the strongest winds. That being
said, winds are still expected to increase tonight under dry
conditions.
Thursday after is forecast to have the winds rotate to more onshore
and begin to slowly push the smoke away from the Bay Area and into
the Central Valley. By Saturday, the next trough will develop in
British Columbia and sink toward Southern Idaho. This could bring
the next round of northerly, offshore winds, but the latest Euro and
GEFS ensemble models are depicting a much weaker gradient at 500
mb that does not appear to sink as farther south into Northern
California as in previous runs. The GFS deterministic even
characterizes a weak mid level low develop off the Central Coast
keeping onshore and southwesterly winds in place. This is not to
say that offshore winds will not return this weekend, in fact this
past red flag had a low located in Idaho. But it does merit the
need to be monitored. The remainder of the extended forecast
remains on track.
&&
.PREV DISCUSSION...as of 01:42 PM PDT Wednesday...An upper level low
centered over southwestern Idaho continues its gradual movement
east over the Rocky Mountains. This low was the driving force
behind the critical fire conditions that were present last evening
which brought dry conditions and gusty offshore winds. Winds have
generally subsided, but are still out of the north-northeast with
gusts between 15 to 20 mph, with highest elevations occasionally
gusting up to 30 mph. With winds that have weakened and humidity
levels from 20 to 40 percent, it was determined that the Red Flag
Warning over the North Bay Mountains and the East Bay Hills could
be cancelled early. However, dry conditions still prevail. Even
though winds have weakened, a new fire, the Cache Fire, near
Clearlake in Lake County outside has started recently. Even though
a Red Flag is not valid in our county warning area, caution is
urged so that no one becomes the spark that the critically dry
fuels could use to start another fire.
Higher resolution HRRR, NAM and WRF models are all depicting an
increase in winds later tonight, mainly over Napa County. Winds
will likely increase between 20 to 25 mph, with isolated gusts
around 30 to 35 mph along the highest peaks and ridgetops with
relative humidity levels down in the 20 percent range with brief
periods of time in the upper teens. While the increase in
offshore winds and dry conditions make for elevated fire concerns,
the short temporal range and minimal land area covered is the
main reason there is no valid red flag warning specifically issued
for this event. But this event will be monitored through the
night.
The upper level trough has also provided an influx in smoke to the
region. The northerly winds are pushing smoke from the River Fire,
the Dixie Fire, and other fires in Northern California and Oregon
southward. Many ASOS sites around the Bay Area are recording a
ceiling between 4000 and 5000 feet. But that ceiling is not from
clouds, it is from the smoke.
Additionally to the fire concerns and increase in smoke, the
northerly winds are pulling a cooler air mass southward toward the
Central Coast. Many stations are reporting temperatures in the 70s
with isolated low 80s for far interior areas expected. While much
of the cooler temperature is brought to the area from the cooler
air mass, the previously mentioned smoke will also act to prevent
more daytime heating to occur Wednesday afternoon.
By Thursday, the trough starts to move far enough away eastward to
providing more zonal westerly flow in its wake. The westerly winds
aloft will help to push some of the smoke toward the Central
Valley on Thursday afternoon. With onshore winds, expect
temperatures to be fairly similar tomorrow.
Another upper level trough looks to develop over southwestern
British Columbia Friday afternoon, sinking down over the Pacific
Northwest on Saturday. It looks to drop southward, tightening the
pressure gradient and bringing offshore winds back to the North
Bay. Exact timing and magnitude of the winds are still to be
determined. For now it will be closely monitored. If the track of
the trough remains where models currently project it to go, it
should remain far enough away to have conditions be similar to
tonight, where an increase in an occasional higher gust at higher
elevations may be possible keeping fire concerns high.
The long range forecast shows a 594 dm high at 500 mb develop over
Texas early next week, and slowly retrograde back towards the
state of California. A stationary short wave trough looks to
develop along the coast extending down past the Mexican border. If
it remains in place, it will keep southwesterly onshore winds in
place, but how it interacts with the high will be watched closely.
Temperatures will likely increase next week as a result, but not
resulting in a heat wave at this time.
&&
.AVIATION...as of 05:35 PM PDT Wednesday...For the 00z TAFs.
Skies over the district are free of clouds but filled with
widespread smoke and haze. A weak marine layer lid is evident at
about 1200 feet in the new 00Z KOAK sounding, and at around 2000
feet in the latest Bodega Bay and Fort Ord profilers.
Near surface smoke remains the primary aviation concern tonight,
though marine stratus ceiling onset is expected later this
evening at both KMRY and KSNS. Bay Area terminal visibilities
will continue to vary between MVFR and VFR, and slant range
visibilities will be reduced.
Vicinity of KSFO...VFR first part of the evening, then low
confidence forecast of visibility reduction into the MVFR range
beginning around mid-evening due to wildfire smoke. Marine
stratus ceiling development is not expected either overnight or
Thursday morning. Onshore winds to around 15 kt, diminishing later
in the evening.
KSFO Bridge Approach...similar to KSFO.
Monterey Bay...VFR through mid-evening, then low-to-moderate
confidence in forecast of MVFR stratus ceiling development late
evening. Hazy aloft due to smoke, with some reduction in both
slant range and surface visibilities possible at times. Onshore
winds 10 to 15 kt into the first part of the evening then
diminishing.
&&
.MARINE...as of 08:56 PM PDT Wednesday...Moderately strong
northwest winds prevail over the northernmost outer waters.
Associated locally steep waves will result in locally hazardous
seas conditions. Mixed seas continue with a longer period
southerly swell and short period northwest waves at 8 to 10
seconds.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm
&&
$$
PUBLIC FORECAST: DK
AVIATION: Blier
MARINE: Blier
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Area Forecast Discussion
National Weather Service Nashville TN
907 PM CDT Wed Aug 18 2021
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Current channel of moisture now moving toward the Plateau. A slow
weakening trend is expected but will bump the near term pops up
just a bit across that area. Otherwise, still looking at a second
wave late tonight. Latest Hrrr focuses on southern middle TN as we
approach dawn, in terms of a return of showers and tstms. Current
weather and pop grids look to be on track. Only other change will
be to add some patchy late night fog, however.
&&
.AVIATION...
00Z TAF DISCUSSION.
Unsettled weather pattern is upcoming for the taf sites over the
next 12 to 18 hours. Moist southwesterly flow will continue to
channel waves of moisture across the area. wave number 1 will
effect the mid state between 00Z and 04Z. Br vsby restrictions and
some low cigs will prevail from 04Z thru 12z. Wave number 2 will
traverse middle TN in the morning, between 12Z and 18Z. Midday on
Thursday, the upper trough axis will begin pulling east of the
area and we will see a reduction in convective coverage and
intensity. Vcts inclusion will be all, at that time.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......21
AVIATION........21
Area Forecast Discussion
National Weather Service Pocatello ID
246 PM MDT Wed Aug 18 2021
.SHORT TERM...Today through Friday night. An upper level low is
centered currently over southwestern Idaho. It is bringing
widespread showers and isolated thunderstorms over our eastern
areas currently. Expect additional isolated to scattered showers
and isolated thunderstorms this afternoon, mainly in the northern
Central mountains. Look for an additional 0.25 to 0.50 inch of
rain in the these areas. However, the Bear lake area and Island
park area may see locally heavier amounts. Models show this upper
level low to move south and east over the Utah/Idaho line by
Thursday afternoon before moving north and east over western
Wyoming by Friday. This will lend well for the Island Park area
and Eastern Highlands to continue to get rain on Thursday. An
additional 0.25 to 0.50 inch of rain with locally higher amounts
is possible for Thursday. Some light precipitation is also
possible over the rest of the area, especially for the mountains
near Mackay extending back along the Montana Divide on Thursday.
Models show northwest flow setting up by Friday bringing overall
dry conditions, though some light precipitation is possible for
the Island Park area. Temperatures will be cold through the
period. Expect 20 degrees below normal today before warming
slightly by Friday becoming only around 10 degrees below normal.
Wyatt
.LONG TERM...Saturday through Wednesday. Our next storm will be
moving through Saturday into Sunday. Trends continue to show a
slower push across Idaho, keeping showers and storms going into
Sunday evening. This also means we will remain slightly cooler on
Sunday as well. This should end up being another decent rain maker
especially over the southern and eastern highlands. For Monday, the
trends in all of the models and cluster forecasts show a deep low
over southern Canada, and a lingering trough over the Pacific
Northwest and northern Rockies. This will kick off isolated showers
and storms along the Montana border and south along the Wyoming
border. We will begin drying out and warming heading toward the
middle of next week. How quickly depends on when low and trough
across our region shifts north and east. Like the last 2 systems,
there are signs it could be about 24 hours slower than the current
forecast.
Keyes
&&
.AVIATION...Due to an upper level low centered over western Idaho,
showers and thunderstorms are currently occurring and look to
continue mainly along our Eastern Highlands along the Wyoming
border. Additional showers and thunderstorms are expected later
this afternoon for mainly the northern Central mountains, though
they cannot be ruled out for anywhere. Expect MVFR VIS/CIGS for
DIJ through the afternoon into tomorrow morning during heavier
showers on station. IDA has lingering MVFR CIGS. CIGS should
improve this afternoon into the early evening. IDA could drop
lower back to MVFR later this evening into tomorrow morning but
not that likely at the moment. VCTS is possible for all sites
this afternoon until early this evening. Current air
quality/visibility due to smoke is worse over the Eastern
Highlands, though air quality is getting better due to showers.
HRRR smoke model shows better air quality/visibility remaining
through tomorrow before indicating that more smoke is possible to
move back in over the area late Thursday night into Friday. This
will be highly dependent on renewed fire activity over eastern
Washington and northern Idaho.
Wyatt
&&
.FIRE WEATHER...The low over our will persist through early Friday.
An area of more steady rain with embedded storms will eventually s
shift into Wyoming tonight. Behind that, showers and storms should
redevelop, mainly across the central mountains where there has been
plenty of clearing. Isolated showers and storms are possible
elsewhere, but a lot these areas are very cool this afternoon, or
under the dry slot. Heading into tomorrow, showers and storms will
continue...with the low right over us, meaning more coverage
tomorrow. Wetting rains remain likely with most of these showers and
storms, with the lowest potential across portions of 422, 425 and
427. Light snow on the highest peaks is still possible, but it won`t
be that much at all. We will be in between storms Friday, but enough
moisture for showers and isolated storms over the mountains. The
highest potential will remain closer to the Montana border. The
storm for the weekend will be moving through slower, so showers and
storms will linger across eastern areas on Sunday. Beyond that, we
will be drying out and warming up. A low will be moving across
southern Canada with a lingering trough extending back into the
northern Rockies and Pacific Northwest. This keeps the possibility
for showers and storms Monday. If current trends continue, this
pattern may be slow to shift east and allow for the ridge to build
for the middle of next week.
Keyes
&&
.AIR STAGNATION...Overall we have seen improving air quality over
the area due to precipitation and a change in wind direction
aloft. Current air quality is still worse over the Eastern
Highlands. But again, this should improve today because of
precipitation and a gradual change of wind direction aloft. HRRR
smoke model shows this better air quality to remain through
tomorrow before indicating that more smoke is possible to move
back in over the area late Thursday night into Friday. This will
be highly dependent on renewed fire activity over eastern
Washington and northern Idaho.
Wyatt
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Reno NV
232 PM PDT Wed Aug 18 2021
.SYNOPSIS...
As a cold front continues across eastern Nevada, a northerly flow
will spread cooler temperatures into the region overnight into
Thursday. These cooler temperatures will gradually rebound to
warmer more seasonal values Friday. An upper trough moving across
eastern California and western Nevada Saturday could bring
another round of gusty winds and increased fire weather concerns.
Temperatures should remain mostly seasonal. Next week will remain
warm and dry with only light prevailing winds.
&&
.SHORT TERM (through Friday)...
An anomalous upper trough will continue to push east across
northeast NV through Thursday. The gusty north/northeast winds will
gradually diminish going into the evening. The exception will be the
higher valley areas of the Sierra where gusty conditions should
continue overnight. A direct result will be cooler temperatures
spreading over the Sierra and western NV. Lighter winds and
gradually warmer temperatures will accompany higher pressure
moving into the region.
Smoke and wind will continue to be the immediate topic of discussion
through the remainder of the workweek. The expected northerly
wind flow has mixed down and taken hold this afternoon. As
momentum continues into the evening, thicker smoke layers will
spread south and disperse more quickly over western NV going into
the evening. Some Sierra locations will gradually see improving
visibility and air quality overnight but a return to lower quality
air is inevitable as the wind lightens with a decreasing pressure
going into Thursday. Current HRRR Hi-Res simulations show
indications that smoke will gradually spread east back over
eastern Sierra locations later Thursday afternoon and evening.
Hence, smoke from the Dixie and Caldor fires could back into our
region largely west of Highway 395 from NE California to the Tahoe
basin. But with model-derived smoke guidance comes increased
uncertainty to any possible outcome 24-48 hours out.
Temperatures locally were significantly cooler this afternoon as
cooler air extends further south across the Sierra and western NV.
This anomalous but very welcome cool-down will continue into
tomorrow with highs some 10-15 degrees below seasonal values. The
real sensible change happens overnight with low temps that will be
a tease of Fall. So you may have to break out a sweater or
sweatshirt if you venture out later this evening. Enjoy this brief
taste of autumn because next week the more summertime temps will
return to the region. Little change was applied to this portion of
the short-term NBM guidance. Low in the 40s in cooler western NV
valleys such as Minden, Spanish Springs, Stead, and Smith Valley,
and hovering close to freezing for most mountain communities.
-Amanda
.LONG TERM (Saturday onward)...
Gusty winds will increase across northeast CA and western NV
Saturday as an upper short wave drops into the Pacific Northwest
that will drag a trough across the region. Ensemble guidance
seems to favor a wind gust potential up to 30-35 mph over the
northern Sierra which could create another period of localized
elevated fire weather concerns. These same winds may bring an
increased chance of blowing dust north of I-80 and east of US 95
in Churchill and Mineral Counties. The increased risk of a few
showers and maybe an isolated thunderstorm or two along our common
border with NE CA and Oregon should be the only signal of the
passage of the weak frontal boundary escorting its upper-level
cousin. A slight risk of an isolated late afternoon thunderstorm
or two east of US-95 in Churchill and Mineral County is a real
possibility as well.
Highs on Saturday and Sunday look to be at or slightly below normal,
mainly in the mid to upper 80s for lower valleys except closer to 80
for areas north of Susanville-Gerlach, and mid-70s for higher Sierra
valleys. Overnight lows will hover mostly around seasonal normal
in the 50s for western NV valleys, mostly 40s in higher valley
areas, with 30s for most higher Sierra valleys
An upper trough digging in over the eastern Pacific and upper
ridging building back over the Four-Corners into the Great Basin
region will increase a stable southwest upper flow over western NV
the first half of next week. This means a gradual warming trend will
return daytime highs into the more seasonal low-mid 90s for lower
valley and 80s for higher Sierra valleys. A weak late-day zephyr
will continue into the weekend with ensemble guidance showing a
reduced potential for enhanced breezes. -Amanda
&&
.AVIATION...
* Smoke will continue to bring periods of MVFR to IFR conditions
to area terminals today through 00Z. TVL, TRK, CXP, and MEV
will be most affected and warrant extra scrutiny. Even SVE
should see a brief period of VFR conditions. As flow turns more
northerly surface conditions should see a gradual improvement in
both VIS/CIG going into the evening. Some periods of MVFR in
smoke are still possible for MMH going into the evening as
thicker smoke layers converge in that area of the central
Sierra.
Improved flying weather and VFR conditions area-wide for tomorrow
and possibly into Friday morning as forecast winds remain mostly
E-NE. Upper winds are expected to shift from the west and
southwest going into Friday afternoon. Wind shear issues are still
possible at MMH into the evening as winds across area ridges
continue to gust into the 30-40kts range. -Amanda
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
950 PM CDT Wed Aug 18 2021
.UPDATE...
The latest round of showers and thunderstorms have largely exited
the area, but a couple of areas of light to moderate rain are
still moving through portions of Southeast Oklahoma and
Southwest/Southern Arkansas. Similar to the last couple of nights,
redevelopment is likely across Southeast Oklahoma, Southwest
Arkansas, and Northeast Texas as another mid-level disturbance
approaches the ArkLaTex and combines with a southwesterly
nocturnal low-level jet, with additional development possible
south of Interstate 20 near or just after daybreak.
PoPs were updated to reflect current thinking. Some edits were
also made to the low temperatures and hourly temperature grids
based on the latest observations. Updated text products will be
sent shortly.
CN
&&
.PREV DISCUSSION... /issued 700 PM CDT Wed Aug 18 2021/
AVIATION...
For the 19/00z TAFs, a band of strong showers and thunderstorms
will continue to move north through Northeast Texas, Southeast
Oklahoma, and Southwest/Southern Arkansas during the first few
hours of the period. Farther south, additional showers and
isolated thunderstorms are also ongoing, but this activity is
already starting to decrease in coverage and intensity. There
should be a relative minimum in the precip for most locations
beginning around midnight. However, redevelopment is expected
across SE Oklahoma, SW Arkansas, and NE Texas just before sunrise,
followed by more scattered strong thunderstorms after 19/18z
during peak daytime heating.
During the break in the precip, MVFR/IFR ceilings and visibilities
developing during the early morning hours. Any patchy fog that
occurs should dissipate after sunrise, and ceilings should slowly
improve back into the VFR range by early afternoon.
CN
PREV DISCUSSION... /issued 238 PM CDT Wed Aug 18 2021/
SHORT TERM.../Tonight through Tomorrow Night/
An unsettled weather pattern, characterized by increased rain
chances, to persist through the short term period. This is the
result of a series of upper-level disturbances progressing
northeast within weak southwest flow aloft. Based on the HRRR
model, another round of convection is forecast to sweep northeast
across the region during the late afternoon into the early
evening hours. May take much of the evening into the overnight
hours for the atmosphere to fully recover resulting in lingering
rain and convection to continue through daybreak. Diurnally driven
convection to again initiate on Thursday afternoon as a mid-level
disturbance and weak surface boundary drift northeast across east
Texas. High precipitable water values will result in locally heavy
rainfall with most storms through the period.
Rain chances to diminish on Thursday night as upper-level ridge
becomes better established areawide.
Otherwise, low temperatures tonight and Thursday night to average
in the low to mid 70s with highs on Thursday in the upper 80s to
lower 90s. /05/
LONG TERM.../Thursday through Tuesday Night/
By Friday morning, any lingering rainfall rainfall chances
associated with the departing trough will be limited to our
northernmost counties. As the upper level ridge over the northern
Gulf moves closer to the ArkLaTex Friday, southerly flow will funnel
sufficient moisture into the area, which coupled with the heat, will
create a setup favorable for diurnally driven convection across most
of the area Friday afternoon, with only east Texas looking to remain
dry.
Consensus among long term models (GFS, ECMWF, Canadian) continue to
show the ridge overtaking our area and parking itself over the Four
State Region by this weekend. This pronounced high pressure will
significantly limit rainfall chances Saturday and Sunday afternoons.
Some lower-end PoPs do make a return early next week, consistent
with diurnally driven sea breeze convection, but the strong ridging
effects will restrict these to our southernmost counties of Texas
and parishes of Louisiana. By next Wednesday, the ridge looks to
retrograde far enough to allow for more northward intrusion of the
sea breeze, with convection south of the I-20 corridor.
Overnight lows will remain in the mid to upper 70s throughout the
coming week. Following NBM guidance, highs will climb into the mid
90s Friday and higher still Saturday, settling in the upper 90s
areawide through the rest of the forecast period. Some sites will be
making a close approach to triple digits early next week. Ultimately
trended 1-2 degrees lower than NBM next Tue/Wed. All the same, heat
indices are on track to be approaching heat advisory criteria.
/26/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 92 76 94 / 40 70 10 20
MLU 75 91 75 92 / 40 80 10 30
DEQ 72 88 74 91 / 50 70 40 20
TXK 74 90 76 93 / 40 70 20 20
ELD 72 89 73 91 / 40 80 20 30
TYR 75 91 77 93 / 40 50 10 10
GGG 75 91 75 93 / 30 60 10 10
LFK 75 93 75 96 / 30 50 0 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
09/20