Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/22
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
521 PM MDT Sun Aug 14 2022
.AVIATION...
00Z TAF CYCLE
Upper high center over the TX Panhandle. Sct showers and tstms over
wrn NM with isold cells over nw and north central NM at 23Z to
diminish aft 03Z. Brief mt obscurations and heavy rain along with
gusty outflow winds associated with the stronger storms. With the
upper high shifting slightly swd by 15/21Z, convection to become sct
over wrn and nrn NM as cells move more to the ne.
&&
.PREV DISCUSSION...240 PM MDT Sun Aug 14 2022...
.SYNOPSIS...
The relative break in the monsoon action that we`ve been experiencing
over the past several days will come to an end as we transition into
a new week. As monsoonal moisture returns to New Mexico and a
backdoor front arrives, this will allow for the increase in storm
coverage areawide, especially starting Tuesday and Wednesday. This
also means that the threat for heavy rainfall and flash flooding
ramps back up, especially on the northern burn scars which have
largely been spared over the past several days. With the increasing
moisture and storm coverage, also look for temperatures to trend
cooler this upcoming week.
&&
.DISCUSSION...
SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)...
Afternoon convection is slightly farther east than forecast with
storms firing as far east as eastern Cibola county. Despite the dry
upper levels, enough low level moisture in the RGV to combine with a
mid-level moisture gradient, helping to destabilize things further,
to result in scattered convection. Showers and storms are forecast
to dissipate shortly after sunset.
Main change to the short-term forecast was to lower precipitation
chances for portions of the middle RGV Monday afternoon. NBM PoPs
are quite overcooked when compared with other trustworthy hi-res
models including the HREF, HRRR and NAM. Monsoon high (centroid over
the Southern Plains) is forecast to sag southwestward to near
Tucumcari by midday Monday. South and southwest winds aloft are
forecast to strengthen somewhat, helping to pull up mid level
monsoon moisture from far southwest NM and into the RGV as well as
over the crest of the central mountain chain Monday. Models continue
with the idea that a relatively robust backdoor front will drop into
northeast NM Monday night. This front is expected to result in
nocturnal convection over the northern quarter or so of the state
Monday night. Overnight heavy rainfall is a possibility for the HPCC
burn scar Monday night due to the front. Storm motion for
thunderstorms over the Sangre de Cristo mountains Monday night will
be to the northeast around 15 mph.
33
LONG TERM...(TUESDAY THROUGH SUNDAY)...
By Tuesday, the main H5 high is centered near the Four Corners area
while a secondary high is centered over west TX. Meanwhile, an
easterly wave tracks westward along the International Border, blocked
from any northward progress by the TX high. The presence of this high
and drier air will likely lead to a downtrend in storm coverage
across the south on Tuesday. The best monsoonal moisture will reside
across northern NM (aided by the arrival of a backdoor front) which
will likely be the hot spot for thunderstorm coverage, increasing
the flash flooding risk in areas that have largely been spared for
several days, including the HPCC burn scar. The backdoor front makes
progress Tuesday night potentially all the way to the AZ border,
which may generate a moderate east canyon wind in Tijeras Canyon and
on the east side of ABQ Tuesday night and into Wednesday morning.
That easterly wave along NM`s southern border stays within that area,
but moisture advection behind the front will be more than enough to
see an uptick in storm coverage areawide Wednesday and Thursday with
the greatest coverage across the north which should benefit from
upslope flow as well.
Model differences exist in the late week period and into next weekend
as a closed low dives southward into the Midwest while another
disturbance perhaps tracks into the western CONUS. The H5 high which
is squeezed between these features perhaps becomes more amplified
over the Rockies, but despite this, the monsoonal moisture looks to
remain in place across New Mexico. A very active pattern continues.
15
&&
.FIRE WEATHER...
Despite the drier weather for much of central and eastern NM over
the past couple of days, the monsoon remains in full swing with no
critical fire weather condtions expected during the next 7 days. A
backdoor cold front is forecast to ramp up thunderstorm activity for
much of the forecast area Tuesday, continuing through the remainder
of the work week.
33
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 PM MDT this evening for the following zones...
NMZ208.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Sun Aug 14 2022
.SHORT TERM...(This evening through Tuesday night)
Issued at 220 PM MDT Sun Aug 14 2022
Forecast concerns with this afternoon package deal with heavy
rain chances this afternoon through Monday.
Currently...Upper ridge axis positioned near the Nebraska/Wyoming
state line this afternoon. Layered PWATs from GFS showing 1.5
inches along and east of the Laramie Range...with near 1 inch
west. Advertised upper shortwave now located in southwestern
Wyoming...moving east northeast out of northern Utah from this
morning. Convection on radar beginning to blossom across southern
Albany and southeastern Carbon Counties...as well as north central
Colorado. Storms are moving a lot more than yesterday...so that
may be a good thing for this afternoon.
Severe storms still a possibility this afternoon as SB CAPE climbs
to 1500 to 2000J/Kg. Southern Panhandle showing slightly higher
CAPE near 3000J/Kg. Very little in the way of shear though and
with long/skinny CAPE profiles...still think the primary hazards
will be heavy rain and flash flood potential.
HRRR and RAP13 simulated radar shows convection becoming
widespread around 23Z across Laramie and southern Albany
Counties...shifting northeast into Platte and Goshen Counties
around 01Z. Probably the best area for severe storms will be the
central and southern panhandle with those higher CAPES forecast.
This mesoscale guidance keeps storms going well into the evening
hours in the Panhandle...not clearing our eastern CWA until after
07Z tonight.
Upper shortwave finally moves east into western South Dakota after
15Z Monday with trough axis clearing the Panhandle after roughly
21Z Monday.See a substantial decrease in PWATS behind the
shortwave...with .5 inch west of the Laramie Range and 1 inch in
the Panhandle. Given possibility of widespread rainfall tonight
and recycling of this moisture for Monday...still kept fairly high
PoPs for Monday afternoon.
Much drier Tuesday afternoon as monsoonal moisture gets forced
south into Colorado through the morning hours. Would think most
areas will be dry Tuesday afternoon.
.LONG TERM...(Wednesday through Sunday)
Issued at 220 PM MDT Sun Aug 14 2022
Long term forecast remains on track through the end of the week. The
plume of monsoonal moisture starts to break down across the area
Monday night as the upper-level ridge sitting over the High Plains
begins to broaden and shift further west. As a result, PWATs across
the CWA drop down to about climatological normal with minimal storm
chances expected through Thursday. Cannot rule out daily isolated
thunderstorms during the afternoon hours as subtle disturbances
within the ridge may trigger some development. However, storms
should mainly stick to the high terrain and immediate adjacent
plains. Another result of this pattern change are cooler
temperatures. Many places across the CWA will see their temperatures
drop to normal or even slightly below normal for this time of year.
For the most part, high will be in the 70s and 80s through the end
of the week.
Things could get interesting again next weekend with the potential
for another surge of monsoon moisture. Both the GFS and ECMWF have a
similar set-up, but differ on where the better moisture sets up. GFS
has the moisture plume west of the CWA due to an upper-level low
sitting over the South Dakota/Iowa border. ECMWF puts the moisture
plume over the western part of the CWA as it places this low further
east over the Great Lakes. Fortunately, there is still plenty of
time for the models to iron out a solution for next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 521 PM MDT Sun Aug 14 2022
Wyoming TAFS...VFR, except for occasional MVFR and wind gusts to
30 knots in thunderstorms until 02Z at Laramie and Cheyenne.
Thunderstorms in the vicinity and wind gusts to 25 knots at
Rawlins until 02Z. Wind gusts to 25 knots at Cheyenne after 15Z
Monday.
Nebraska TAFS...VFR, except for MVFR and wind gusts to 30 knots in
thunderstorms until 06Z, and IFR at Chadron and Alliance from 09Z
to 15Z.
&&
.FIRE WEATHER...
Issued at 220 PM MDT Sun Aug 14 2022
Monsoon moisture in place through Monday will keep fire weather
concerns at bay. Good chances for showers...storms and wetting
rains. Begin to dry out from north to south Monday with monsoon
moisture getting forced south...as upper high pressure builds
across western and central Wyoming. Afternoon humidity stays above
critical levels through Wednesday before we begin to flirt at
critical afternoon humidity Thursday.
&&
.HYDROLOGY...
Issued at 221 AM MDT Sun Aug 14 2022
Plentiful monsoonal moisture will continue to impact the CWA through
Monday. Ensemble members prog precipitable water values between 1"
and 1.5" along and east of the Laramie Range today and tonight, and
western Nebraska Monday. Showers and thunderstorms will continue to
be efficient rain producers. 0.5-0.75" in 30-45 minutes over the
Mullen burn scar may result in flash flooding and debris flows.
Excessive rainfall Saturday afternoon in Laramie caused flash
flooding, with the Laramie River at Laramie rising 4 feet in less
than an hour. Heavy rain over and upstream may result in additional
rises this afternoon and evening. The Areal Flood Watch remains in
effect through late Sunday evening.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Flood Watch until midnight MDT tonight for WYZ103>107-109>118.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...SF
AVIATION...RUBIN
FIRE WEATHER...GCC
HYDROLOGY...MJ
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
945 PM CDT Sun Aug 14 2022
...New UPDATE...
.UPDATE...
Issued at 931 PM CDT Sun Aug 14 2022
The surface low is now located just south of Laredo and moving slowly
west. Mesoanalysis reveals strengthening low level winds along the
Mid Texas Coast and an area of increasing deep layer moisture flux
convergence has developed in this region. An intense band of
convection has developed from Aransas County inland into Bee and
Goliad Counties. The latest HRRR runs have picked up on this and are
moving this band northwest into portions of Karnes, Atascosa, and
Wilson Counties over the next 1-3 hours where favorable thermodynamic
profiles still reside. Overnight, as the low drifts into Mexico, the
HRRR suggests additional strengthening of bands into portions of the
Winter Garden region (Frio, Zavala, and Dimmit Counties), before
potentially expanding up the Rio Grande into Maverick, Kinney, and
Val Verde Counties Monday morning.
There is the potential for some locally heavy rainfall across these
areas of the CWA overnight and Monday. The most immediate concern
will be Karnes and Atascosa Counties, where WPC has recently
highlighted this area for the potential for some rainfall rates up to
3" per hour should the heavier band making it this far inland.
&&
.SHORT TERM...
(Tonight through Monday night)
Issued at 239 PM CDT Sun Aug 14 2022
The upper air pattern across the U.S. shows a large upper level
ridge over the Rockies and Central/Northern Plains while a fairly
deep upper trough is over the NE United States. The low pressure
area that was over the western Gulf yesterday and overnight has
moved ashore in south Texas and the surface observations and radar
show the circulation center near Alice. Because of the counter
clockwise flow around this system, deep 2+ inch PW moisture has
moved into South Central Texas. A few bands of showers and isolated
storms have been moving west during the day today giving some folks
some brief heavy downpours. Most rain totals so far have been a 1/4
inch or less although a few totals are approaching 0.50 inches. Much
heavier convection and significant banding is occurring off the
BRO/CRP coast. This is creating a fairly large mid and high level
cloud deck which has helped to keep afternoon temps down several
degrees especially over the southern CWA. Out west near DRT has been
the only area that has been in full sun today, and thus has the
warmest temps. Have lowered temps already across the north and east
for the rest of the afternoon, but might have to do it one more time
based on the latest metars.
As the sun goes down, most of the convection will decrease across
our cwa. CAMs show little to no POP across the northern half of the
cwa overnight. However, with some night time development likely
closer to the circulation overnight, keeping chance pop (30-50
percent) basically along and south of Highway 90...to include the
SAT area. QPF overnight could be in that 0.25-0.50 inch range
across the far southern areas into the Rio Grande Plains. Clouds
should be fairly prevalent overnight into Monday morning with lows
in the 70s.
The highest pop follows the low pressure area as it heads west into
Mexico by Monday morning. As we see with many lows that head into
northern Mexico this time of year, it will likely pull moisture up
the Rio Grande and result in some scattered to numerous SH/TS over
our SW zones and along the Rio Grande...into Monday night. QPF on
Monday from Eagle Pass up to DRT could result in rains over 1
inch...isolated higher totals due to the high PW values over 2
inches. Not out the question that some spots could easily see a
couple inches of much needed rainfall. Monday will see temps rebound
especially over the north where POP will remain very low and more
sun is expected.
&&
.LONG TERM...
(Tuesday through Sunday)
Issued at 239 PM CDT Sun Aug 14 2022
The long term begins as the remnants of what was Invest 98-L vacate
to West Texas and northern Mexico. A high-amplitude synoptic pattern
will prevail in its wake, with mean troughing across the eastern half
of the CONUS and well-defined ridging in the Mountain West. Both
features should become most pronounced by the Wednesday- Thursday
timeframe as a closed mid-level low develops over the northeastern
US. Stuck between the two features locally, winds will become
predominantly northwesterly in the 700-300 mb layer as this occurs,
helping to drive a surface cold front into the state through early
Thursday morning. Said boundary will begin to return north as a warm
front from Friday afternoon through next weekend.
With the early week inverted trough continuing to distance itself
from the region, expectation is that the vast majority of the
measurable rainfall will have concluded by the beginning of the
period. Have thus gone with a largely dry forecast across most of
the area on Tuesday, with the exception of the Rio Grande Plains
where straggling isolated to scattered convection could hold on
through the afternoon hours. Don`t anticipate much in the way of
additional accumulation, but any activity could produce an
additional several hundredths to one tenth of an inch of new
rainfall on top of the totals seen through the conclusion of the
short term. Given this potential, anticipate that the coolest high
temperatures will be found along the Rio Grande Tuesday afternoon,
where readings in the low 90s are likely. This will be in stark
contrast to areas along and east of the I-35 corridor, where dry
conditions and a lack of residual cloud cover should allow temps to
top out in the upper 90s to low 100s.
Wednesday should be the driest and warmest day of the forecast
period, particularly in spots along the I-35 corridor and within the
Coastal Plains. Widespread high temperatures in the 99-103 range,
along with heat index values spanning from 103 to 108, could create
potentially hazardous conditions for those planning to spend
prolonged periods of time outdoors across this portion of the CWA.
Will continue to monitor trends for any potential heat headlines
that may become necessary. Expect slightly lower temps and heat
indices across the southern Edwards Plateau where greater cloud
cover will be in place.
The southernmost progress of the cold front mentioned above
continues to be a source of uncertainty as of this forecast package.
Progs continue to point to the possibility of the boundary reaching
the Edwards Plateau prior to stalling out during the day on
Thursday. Regardless of where it ultimately ends up, the front
should be in close enough proximity to the region to trigger
scattered showers and thunderstorms by the afternoon hours on
Thursday. Chances should continue on Friday, with activity being
strongly influenced by daytime heating. While too early to speak to
precise QPF amounts, heavy downpours could bring pockets of
beneficial rainfall to portions of the region. Isolated storm
chances will continue through next weekend as the front returns
north from the area.
&&
.AVIATION...
(00Z TAFS)
Issued at 621 PM CDT Sun Aug 14 2022
At 23Z the surface low was located roughly between LRD and HBV. The
low will continue W tonight and then more NW in Mexico Monday. A
decrease in coverage of SHRA away from the center of the low is
expected initially after sunset. Guidance then suggests nocturnal
expansion in coverage 06Z-12Z SW of SAT and just S of DRT. Latest
HRRR runs indicate the precipitation expanding into DRT after 12Z and
continuing into the early afternoon. A few SHRAs could potentially
be in the vicinity of SAT/SSF as well. There is a high degree of
confidence that MVFR ceilings will also develop overnight and into
Monday morning along and west of a AQO-SAT-PEZ line, with a potential
for pockets of IFR ceilings, especially in precipitation SW of SAT
to the Rio Grande. Confidence is lower in the MVFR ceilings into
AUS, but for now we have included this in their TAF.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 75 97 75 102 / 10 10 0 0
Austin Bergstrom Intl Airport 75 97 73 101 / 10 10 0 0
New Braunfels Muni Airport 75 97 73 99 / 20 20 0 10
Burnet Muni Airport 74 96 75 100 / 0 10 0 0
Del Rio Intl Airport 77 87 76 93 / 30 70 50 40
Georgetown Muni Airport 75 99 76 101 / 0 10 0 0
Hondo Muni Airport 75 92 74 97 / 40 50 10 10
San Marcos Muni Airport 73 97 73 99 / 20 20 0 10
La Grange - Fayette Regional 74 98 74 99 / 10 10 0 10
San Antonio Intl Airport 76 93 75 98 / 30 40 10 10
Stinson Muni Airport 76 94 76 99 / 40 40 10 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...09
Long-Term...Quigley
Aviation...76
Area Forecast Discussion
National Weather Service Flagstaff AZ
737 PM MST Sun Aug 14 2022
.SYNOPSIS...An active monsoonal pattern will continue across
northern and central Arizona through the upcoming week. Heavy
rainfall leading to flash flooding will continue to remain a
threat as a result. As a reminder, be sure to avoid flood prone
areas. If you come across flooded roadways...make the smart choice
and turn around, don`t drown.
&&
.UPDATE...Things have calmed quite a bit from earlier today, however,
there are still Flash Flood Warnings out there in some areas.
Rainfall continues, as well, with the threat of nighttime flooding
a harsh reality again tonight. Do not enter floodwaters!
&&
.PREV DISCUSSION /112 PM MST/...Today and tonight...Showers and
thunderstorms have developed across much of the high terrain this
afternoon. RAP Mesoanalysis shows the greatest PWAT and MLCAPE
values over west-central Arizona, as earlier cloud cover from a
decaying MCV has limited instability over the eastern Mogollon
Rim. Storms are expected to continue to increase in coverage
through the remainder of the afternoon into this evening. Deep
monsoonal moisture (PWATs around 1-1.5") and slow storm motions
(~5 kts) this afternoon will result in flash flooding being the
primary hazard with these storms, especially over flood prone
areas (recent burn scars, slot canyons, and low-water crossings).
However, small hail and gusty winds can not be ruled out with any
of the stronger thunderstorms.
Coverage and intensity should begin to decrease after sunset with
the loss of daytime heating. Hi-Res guidance does point towards
lingering stratiform rain with embedded heavier downpours
developing into another MCV overnight across northwestern Arizona
late this evening. Overnight impacts from this system should be
minimal. Any remaining showers and cloud cover Monday morning may
result in delayed or hampered convection during the afternoon.
Monday through Wednesday...Monsoonal moisture gradually begins to
lessen slightly each day over the High Country through mid-week.
Daily shower and thunderstorm chances are expected to remain,
though with slightly decreased coverage each day. Nevertheless,
flash flooding will remain a concern with areas of heavy rainfall.
Thursday through next weekend...A disturbance over the western
Gulf of Mexico tracks westward through northern Mexico through
the upcoming week. As it draws closer, passing over Sonora, deep
monsoonal moisture is pushed northward into Arizona. Ensemble mean
PWAT values from the GEFS and EPS show around 1.5-2" across the
lower deserts of Arizona with 1-1.5" across the High Country. As
a result, an active period in the monsoon, and thus an increased
flash flood risk, look to return for the later half of next week.
&&
AVIATION...For the 06Z TAF package...Isolated shower and storm
activity becoming more widespread Monday after 18Z. Gusty and
erratic winds and MVFR/IFR conditions in and around storms with
light winds/VFR away from storms. Aviation discussion not updated
for TAF amendments.
&&
FIRE WEATHER...Widespread showers and storms will continue through
Tuesday with peak activity in the afternoons. Expect gusty and
erratic winds near any storms. Flash flooding remains possible.
Otherwise, light winds away from storms with little change in high
and low temperatures.
Tuesday through Thursday...Little change. Monsoon moisture will
remain in place with showers and thunderstorms each day.
&&
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 11 PM MST this evening for AZZ004-006>008-
015>018-037-038-104-106>108-115>118-137-138.
&&
$$
PUBLIC...Kobold/Humphreys
AVIATION...Kobold
FIRE WEATHER...McCollum
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Lake Charles LA
1014 PM CDT Sun Aug 14 2022
.UPDATE...
The isolated convection that developed through the afternoon
dissipated early this evening. As has been the case the last
couple of nights, trapped low level moisture below a dry mid
layer may allow for some low cloud or patchy fog development near
sunrise. However, this isn`t expected to be widespread enough to
warrant explicit mention in the forecast as of now.
Upper level ridging will continue to build back across the region
Monday which, combined with the drier mid level air, will keep a
lid on convection although a few isolated storms will be possible
during max heating through the afternoon. The lower cloud cover
will allow afternoon highs to climb into the low to mid 90s along
the I-10 corridor with upper 90s expected across interior
southeast Texas and central Louisiana. The inherited forecast is
in good shape and no significant changes were required.
Jones
&&
.PREV DISCUSSION... /issued 545 PM CDT Sun Aug 14 2022/
DISCUSSION...
For the 08/15/2022 0000 UTC TAF package.
AVIATION...
Radar only showing a couple of showers, none near the terminals.
Not expecting any significant precipitation this evening, and less
than 20% for Monday. Southerly winds around 8-10 kts now expected
to become variable at 5 kts or less this evening and overnight. May
see intermittent MVFR visibility from 09-13z at AEX, otherwise,
VFR expected.
08
PREV DISCUSSION... /issued 401 PM CDT Sun Aug 14 2022/
SYNOPSIS...
The latest WV imagery and UA analysis shows upper ridging beginning
to build back over the area in the wake of the low pressure
system that is now just inland of the TX coast south of CRP. In
addition, some drier air is attempting to infiltrate the region,
but this has not been enough to overcome moisture/instability in
the lower levels, with KLCH radar showing what has mostly been
some scattered showers across SE TX into W LA, and more isolated
convection across SW/S central LA.
Surface analysis shows high pressure has resumed across the northern
Gulf coast, yielding a modest onshore flow over the area. With cloud
and shower coverage a little less than the last several days,
temperatures have warmed to around 90 across the southern zones with
lower 90s across interior SE TX into central LA.
24
SHORT TERM [Tonight through Tuesday Night]...
Minimal changes to the forecast for the next few days as ridging
aloft remains over the region, and surface high pressure prevails
across the northern Gulf. Precipitable water values are expected to
continue falling through Monday, possibly as low as 1.3-1.4 inches
across portions of the area per NAM12 and HRRR PWAT progs. This
should help to inhibit convection across the area on Monday, with
the best, albeit low, chances for any showers or storms across S
central LA during the afternoon.
By Tuesday, slightly better moisture will begin to expand across
SE LA into central and S central LA, and with it, a slight uptick
in PoPs across these areas. Despite this, convective coverage should
66
&&
.DISCUSSION...stay isolated to widely scattered, and mainly east
of a Leesville to Lake Charles line.
As heights build aloft and cloud and shower coverage decrease,
daytime temperatures are expected to climb back to above normal.
High temps are expected to range from the lower 90s across the
southern zones to the upper 90s/near 100 across the northern
zones, with Tuesday a little warmer than Monday. Slightly drier
air mixing down during the day will yield dewpoints in the upper
60s to lower/middle 70s, resulting in max heat index values
between 100 and 108 degrees. At this time, do not anticipate
issuance of any heat advisories for the area, although a few
isolated spots across central LA or the Lakes region of SE TX
could reach criteria for an hour or two either afternoon.
24
LONG TERM [Wednesday through Sunday]...
Global models continue to be in good agreement for the long range
period, showing the break down of deep layer ridging by mid week via
shortwave energy digging through the Plains/Mid MS River Valley.
Rain chances will start to increase on WED, but are still progged at
just below seasonal normals while highs are forecast to remain quite
warm, reaching into the mid/upper 90s and near triple digits across
interior SE TX into Central LA, with more seasonal lower to mid 90s
along the I-10 corridor.
A more robust upstream trof is forecast to dig into the Central
CONUS THU and FRI, nudging a weak frontal boundary to our doorstep
or perhaps just far enough to sneak into northern zones, where it is
progged to meander until retreating back north and/or washing out on
SAT. Copious MSTR pooled along/south of the boundary coupled with
perturbations translating through the W/NW flow aloft will yield
multiple periods of widespread showers and thunderstorms THU and
FRI. The trof is progged to lift out on SAT, and the resulting weak
ridging along with the intrusion of some relatively drier air will
start to bring rain chances back down for the weekend.
13
MARINE...
Surface high pressure will continue to ridge across the northern
Gulf of Mexico through the week. This will produce a mainly light
onshore flow, along with low seas, for the next several days. Rain
chances will remain limited until late in the week when a surface
front is expected to move south into the area.
24
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service New Orleans LA
700 PM CDT Sun Aug 14 2022
...EVENING UPDATE...
Performed a brief gridded update this evening to reflect
radar/short-range guidance thru tonight and into early Monday. Few
decaying showers around the Southshore and over coastal MS/AL caused
by earlier outflow/seabreeze boundary interactions will continue
to dissipate thru sunset. Did add small isolated coverage in these
areas, but we`ll clear out nicely going into tonight.
No major changes in the thinking for Monday with continued less
overall afternoon shower/storm coverage thanks to slightly drier
air in the profile aloft. Focus for shower (and some storm)
coverage Monday will be primarily along lake/seabreeze boundaries
and where they intersect with remnant outflow boundaries from
showers so generally hit-or-miss and limited in coverage. Not
seeing any distinct severe weather parameters jumping out per
latest HRRR soundings, but a slight uptick in the low to mid-level
dry air could help with entrainment in any rogue stronger updraft
to deliver brief, gusty downdraft winds in excess of 30 to 40 mph
but will not be a widespread issue.
Additionally, did notice short-range guidance hinting at
convective development across central AL/GA in response to a
southward drifting cold front, which becomes deep enough to ride
the SSE mean flow into the northern Gulf. Consensus along HREF
members are to keep this potential activity east of our area, but
will have to watch subsequent CAM runs if it can clip parts of
coastal MS Monday evening but, not including that risk in the
forecast for now. KLG
&&
PREV DISCUSSION... /issued 359 PM CDT Sun Aug 14 2022/
SHORT TERM...
Not really much in the way of anything unexpected across the area
today. Weak ridging over the area has brought in slightly drier
air and kept rain coverage down for the most part today.
Model sounding PW values are down below 1.9 inches across most of
the area. While that normally would not sound all that
impressive, given the events of the last few weeks, we will take
it. Any shower activity should begin to wane as the afternoon and
evening progresses.
As we begin the new work week, rain chances will continue on the
lower side, especially compared to the recent norms as ridging
tries to hold in place. Lower rain chances does mean temperatures
will rise into the lower 90s in most locations with enough
moisture still around to make heat index values noticeable.
Generally should see values in the 102-106 range tomorrow and
Tuesday which keeps us below heat advisory criteria.
LONG TERM...
By mid-week a series of disturbances riding across the central
Plains and with riding sliding east over Florida and the Atlantic,
will allow for a slight increase in rain chances. That said, the
front will not likely make much headway towards our area Wednesday
and will allow for at least one more day of more typical summer
rain chances. As the boundary shifts slightly south and
disturbances make their way closer to the forecast area, rain
chances are likely to be on the rise again by Thursday and Friday
as well as the weekend. Did not stray much from the NBM with rain
chances increasing again after Wednesday.
AVIATION (00Z TAF DISCUSSION)...
Only activity on radar this evening remains to be a few isolated
showers in the vicinity of MSY, but will dissipate by 01-02Z this
evening. Otherwise, expect VFR flight conditions overnight
tonight into early Monday for all area terminals. Can`t rule out
some light ground fog in and around KMCB between 11-12Z, but
chances will be lower than previous days and not anticipating
widespread dense fog or impacts to follow. KLG
MARINE...
A weak frontal boundary will continue to move closer to our
region before stalling and eventually dissipating early in the
week. This feature will likely weaken pressure gradient just
enough to help provide overall favorable marine conditions. That
said, diurnally driven convection will still be possible...albeit
a bit more limited in terms of coverage. Still cannot rule out
locally higher winds and seas with the stronger showers and
storms, but, it`ll probably be about Wednesday before areal
coverage of storms gets anywhere near as widespread as the past
week. 35
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 72 93 73 93 / 10 30 10 40
BTR 74 94 75 95 / 10 30 10 40
ASD 75 94 75 94 / 10 30 10 40
MSY 77 93 77 92 / 10 30 10 40
GPT 76 93 76 93 / 20 40 20 40
PQL 75 93 75 93 / 20 40 20 40
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Las Vegas NV
147 PM PDT Sun Aug 14 2022
.SYNOPSIS...Flash Flood Watch continues today for scattered
thunderstorm activity in southern Nevada and northwestern Arizona.
Anomalous moisture in place continues to aid thunderstorms in
producing heavy rainfall and widespread flash flooding, particularly
in areas of higher terrain. Thunderstorm chances persist each
afternoon through the forecast period, with best chances late-week
as we gear up for a possible tropical influence.
&&
.DISCUSSION...Today through the week.
Anomalous moisture persists for the Desert Southwest, with over an
inch and a half of PWAT in the 12Z Las Vegas sounding. Yesterday,
convection was slow to start, and experienced a bit of inhibition
due to early-morning cloud cover across the region. This morning,
skies cleared early, allowing the surface to sufficiently heat, with
the first Flash Flood Warning issuance of the day at 12:27pm PDT. As
expected, isolated thunderstorms with frequent lightning and locally
heavy rainfall favored the high terrain so far this afternoon, but
as valleys reach their convective temperatures, we expect areal
coverage to greatly increase through the afternoon. There remain a
number of vulnerable locations across our forecast area due to
repetitive monsoonal flooding. The majority of roads through Death
Valley National Park remain closed due to flood damage. The Mojave
National Preserve was able to open the majority of theirs on Friday,
but North Kelbaker Road and Zzyzx Road remain closed. Golden Valley
and Kingman have had numerous flood events so far this season as
well, with widespread flood and heavy rain impacts observed
yesterday. Due to heavy rainfall continuing to target similar areas
each day, soil moisture content has increased, which provides
antecedent conditions prime for additional flash flooding. In
general, isolated thunderstorm activity will wane after sunset.
However, models, including the 18Z run of the HRRR continue to hint
at a northeasterly storm prorogation tonight from southwestern Utah
through Lincoln, then northern Mohave and eastern Clark counties
between sunset and midnight. This storm direction is favorable for
heavy rain in the Las Vegas Valley. Confidence is low at this time
in it coming to fruition... hi-resolution models have hinted at
similar set ups each evening over the last few days, with minimal-to-
no experienced impacts.
That said, the signal for a northeasterly event returns Monday
night, but there are a number of questions about how Monday
convection will materialize, in general. Ongoing convection
overnight tonight has the potential to keep the area socked in with
cloud cover Monday morning. WPC has shifted their SLIGHT risk
eastward, and out of our forecast area entirely for Monday... a
solution that the HREF 3 hour PMM supports. With no clear forcing
signal and in coordination with our neighbors, opted out of
extending the Flash Flood Watch into Monday at this time. The 18Z
HRRR shows +40 dBZ convection across northern Inyo, Esmeralda, and
central Nye counties Monday, but due to PWAT regression, these
storms are not as likely to produce the same magnitude of rainfall
that we have experienced the last few days across the Mojave Desert.
Confidence will increase either for or against a Monday watch
tonight with the 00Z HREF run, but at the moment, WPC, HREF, nor NBM
are enthused with rain totals tomorrow. An area of high pressure
will build over northeastern Nevada and southern Utah tomorrow... a
pattern that often results in vorticity ejections southwestward
through Clark County, producing heavy rain in the Las Vegas Valley.
Stay tuned as we work to resolve some of the finer details of the
forecast.
Regardless, we`re in the midst of an active monsoon with anomalous
PWATs stretched across the Desert Southwest. Mountain zones can
expect daily afternoon thunderstorms with greatest chances the
further east you move through our CWA - additionally, any areas
along outflows from the previous day`s MCS activity. Late week, a
potential tropical influence may work to drastically increase PoPs
and QPF across our forecast area. According to the NHC, the
disturbance in question is currently positioned over Corpus Christi,
where 12Z soundings read over 2.5 inches of PWAT. This system is
expected to move westward across northern Mexico this week, which
could influence late-week monsoon activity across the Desert
Southwest.
&&
.AVIATION...For Harry Reid...Light winds this afternoon, generally
favoring an easterly direction. Speeds around 5-8 knots.
Thunderstorm development expected this afternoon on the mountains
south and west of the valley. These could send outflow winds to the
terminal, but the prospect of storms in the valley appears to be
fairly low at the moment. Winds should turn southerly in the late
afternoon and evening, with speeds around 8-10 knots. There is a low
possibility of northeasterly outflow winds, and potentially storms,
reaching the valley this evening, but confidence is not high enough
to include in the TAF at this time. Otherwise, expect light
southwest winds overnight, turning to the east tomorrow morning.
SCT-BKN mid and upper-level clouds throughout the TAF period.
For the rest of southern Nevada, northwest Arizona and southeast
California...Light winds expected across the area with scattered mid
and upper-level clouds. Afternoon thunderstorms are expected to
develop in the vicinity of the Las Vegas Valley and Colorado River
Valley sites. Outflow winds, and possibly TSRA, could impact these
airports, with the best chances at KHND, KIFP, and KEED. Thunderstorm
activity is expected to wane in the evening, though there is a
low possibility of storms/outflow moving southwest into the Las Vegas
Valley this evening. There remains a fair amount of uncertainty in
this scenario, thus opted to not include in the respective TAFs.
Should confidence increase, amendments will be needed.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Varian
AVIATION...Woods
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