Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/12/21
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
741 PM EDT Tue May 11 2021
.SYNOPSIS...
A weak front drops across the region tonight. High pressure
builds north of the region through midweek...as low pressure
tracks across the southeast states. High pressure builds over
the area Thursday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 740 PM EDT Tuesday...
Weak cold front continues to make southward progress this
evening. Radar has been rather quiet for our area so far but CAM
guidance continues to show the potential for light showers along
and ahead of the frontal boundary. Clouds are increasing across
the north early this evening.
Increasing clouds trend continues tonight, as weak front drops
across the local area. HRRR time-lagged/ARW is showing about the
worst case scenario of some isolated to widely sct showers
dropping (mainly) across the northern neck and eastern shore
through the course of this evening. Cannot rule out a quick
sprinkle most anywhere over the area this evening, so will throw
in a slight chc PoP for most zones north of the NC/VA border by
midnight. Temps look to drop off quickly initially, but
stabilize with increasing cloud cover late and overnight. Lows
in the low to mid 40s NW...mid 40s to near 50 central VA/MD
eastern shore and upper 40s to low 50s Hampton Roads/NE NC and
VA eastern shore.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 225 PM EDT Tuesday...
Cool (modifying) Canadian high pressure builds across the
region from the Ohio Valley on Wed, as several weak shortwaves
track along the slow moving frontal boundary along and south of
our southern CWA. Mostly cloudy/overcast to start the day, with
some light overrunning rainfall over the US-58 corridor along
and south of the VA/NC border. Overrunning light rain
overspreads the southern one-third of the area tomorrow morning,
as slow clearing ensues across the north. There will be a
gradual trend toward clearing for central and southern tier of
counties from midday into the afternoon. Cool again w/ NNE winds
and highs from the l-m60s N to the u50s- l60s S.
High pressure continues to build into the area Wed night-Thu,
and will result in a clearing sky and cool/dry wx. Meanwhile,
weak low pressure will move along the stalled front across the
Gulf coast region. Early morning lows Thu morning in the l-m40s
u40s- around 50F right along the coast. Mainly sunny Thu w/
highs from the m60s to around 70F. Lows Thu night/Friday in the
l-m 40s inland, upper 40s to low 50s along the coast.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 200 PM EDT Tuesday...
Aforementioned low pressure crossing the deep south toward the
SE coast will bring some lingering clouds, especially central
and south to begin the day on Friday, and ECMWF does paint in
some low QPF...but with the remainder of guidance and NBM nearly
dry will keep PoP in silent range for now. Sfc high then builds
over the region late Fri through this weekend, eventually
sliding offshore into early next weekend. This should translate
to slowly moderating temperatures throughout the medium range
forecast period. Friday`s highs start out in the upper 60s to
lower 70s and by the time we reach the weekend, highs will be in
the mid to upper 70s. Early morning low temperatures start out
in the upper 40s to lower 50s over the weekend, and then lower
to mid 50s as we turn to early next week.
Looking ahead, strengthening Bermuda high looks to portend a
continuation of the warming trend into the middle of next week,
with more typical diurnally-driven convection by the middle of
next week.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 740 PM EDT Tuesday...
Weak cold front is still progged to drop south this evening and
tonight with at least some potential for light showers along and
ahead of the front. Clouds are increasing across the northern
terminals and these clouds will filter southward with time
tonight into Wednesday. Left VCSH at SBY tonight where
confidence in seeing some showers is highest. Winds are
generally from the south or west ahead of the front but will
quickly swing around to the north behind the boundary. Will show
northerly winds increasing to ~10 kt with gusts 15-20 kt for a
period overnight. Clouds hang on across the south for at least
the first half of the daylight hours across the southern
terminals with more clearing expected for the northern half of
the area.
Outlook: Expecting mostly VFR conditions Wednesday into the
late week period. Northerly flow continues through Thursday
before high pressure builds near the region.
&&
.MARINE...
As of 230 PM EDT Tuesday...
Front is well south of the area this afternoon with weak surface
high pressure right off the coast. Calm marine conditions currently
with a light onshore flow. Waves in the bay around a foot and seas 2-
3 ft.
A weak boundary moves across the area late tonight and strong high
pressure builds in from the NW. Winds become northerly and increase
to 15-25 kts with gusts around 30 kts over the Bay, rivers, southern
coastal waters, and Currituck Sound. SCA`s go into effect late
tonight for these areas and run through Wednesday morning. Winds in
the middle and northern coastal waters are expected to remain below
SCA criteria. There may be a narrow window of 2-3 hours early
Wednesday morning where wind gusts approach 25 kts, but can more
than likely be handled with a Marine Wx Statement rather than a SCA.
Waves in the bay and seas will increase to 2-4 ft overnight, with
some 5 ft seas possible over the southern coastal waters.
Winds diminish to 5-15 kts by Wednesday afternoon along with waves
subsiding to 1-2 ft and seas 2-3 ft as the pressure gradient
relaxes. High pressure and sub-SCA conditions expected from
Wednesday afternoon through the remainder of the week and the
weekend.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 1 AM to 10 AM EDT Wednesday for
ANZ632-634-636>638-658.
Small Craft Advisory until 10 AM EDT Wednesday for ANZ630-631-
635.
Small Craft Advisory from 1 AM to 1 PM EDT Wednesday for
ANZ633.
Small Craft Advisory from 1 AM to 7 AM EDT Wednesday for
ANZ656.
&&
$$
SYNOPSIS...MAM
NEAR TERM...MAM/RHR
SHORT TERM...ALB/MAM
LONG TERM...MAM
AVIATION...MAM/RHR
MARINE...CMF
AREA FORECAST DISCUSSION
National Weather Service Albany NY
921 PM EDT Tue May 11 2021
.SYNOPSIS...
After a chilly and breezy day with hit and miss
showers, chances for showers increase later tonight, especially in
the higher terrain where rain may even change to snow showers
in parts of the Adirondacks and southern Greens. The cool and
breezy conditions continue tomorrow with additional scattered
showers possible, especially in southern Vermont. High pressure
builds in for Thursday providing us with plenty of sunshine and
warmer weather.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
UPDATE...00Z sounding was well mixed this evening which kept the
wind speeds up through this early evening. A few showers
extending from central New York was attempting to make it into
the Schoharie Valley. Otherwise, south of the Dacks, skies are
mainly clear. This should aid with the boundary layer to
decouple before the approach of the upstream cold front.
Regional radar depicts the leading edge of the precipitation was
dissipating, likely thanks to the dry column per our 00Z
sounding. However, trends toward a more moist environment should
commence overnight as the threat of showers increases with the
frontal movement from the north overnight. As temperatures are
rather cool already across the higher terrain per the NY
Mesonet, the rain/snow mixture still looks good at this time. So
main update was to sky coverage and tweaks to the PoP/Wx grids.
Overnight lows look good at the moment and closely resembles the
LAV/LAMP guidance.
Prev Disc...Once we past peak heating and approach sunset,
convectively driven clouds should dissipate and we could see a
few hours this evening with mainly clear skies. However, our
main trough axis, as depicted on the latest GOES16 water vapor
imagery, will swing southeastward from Ontario into the
Northeast tonight with cloud coverage and showers increasing in
response to the enhance mid- level convergence overlapped with
sufficient moisture. Latest high res NAM and HRRR both suggest
that the higher terrain areas in the southern Adirondacks,
Taconics, southern Greens and Berkshires will likely have the
greatest potential of experiencing a period of showers tonight,
mainly after 03 UTC through 12 UTC, due to enhanced orographic
lift within the continued northwest flow regime. Even still,
overall precipitation amounts should only range from a few
hundredths up to a tenth of an inch. The trough axis will also
enhance cold air advection and temperature profiles in the
higher terrain areas look to cool enough to support a mix with
or even brief changeover to snow showers. Total accumulations
will be minimal and reserved to the higher peaks of the southern
Adirondacks and southern Greens less than 1 inch.
Otherwise, temperatures tonight fall to mid to upper 30s with
low 30s in the higher terrain. Increasing clouds overnight and
breezy winds will likely mitigate any frost formation.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Breezy west - northwest flow continues tomorrow in the wake of
the trough axis so temperatures will once again be cooler than
normal. However, a closed high in the Midwest will be building
eastward and northwest flow actually will start to advect in
warmer air that will rotating around the periphery of the high.
Therefore, temperatures should be a bit milder tomorrow compared
to today with highs in the upper 50s to low 60s. Despite strong
area of high pressure upstream, we will still will be under the
influence of the broad trough which will be gradually exiting
in the Canadian Maritimes. Therefore, still expecting partly to
mostly sunny morning skies to mix with afternoon clouds as we
reach our convective temperature. In addition, high res guidance
continues to suggest that some scattered showers develop in
response to a secondary trough axis swinging through northern
New England but these showers look to impacts areas mainly
north/east of Albany including Lake George, Washington County,
the northern Taconics, and southern Vermont. BUFKIT profiles
show mid-level lapse rates steepen ahead of the approaching
trough with some weak instability developing (MUCAPE < 250
J/kg). Therefore, we followed suite with WFO Boston and added in
isolated thunderstorms possible for these areas.
Skies clear Wednesday night as upstream high pressure gradually
builds eastward, allowing the pressure gradient to relax. Winds
after midnight should weaken below 5 kts which should promote
radiational cooling. With temperatures falling into the low to
mid 30s in the higher terrain areas of the southern Adirondacks,
eastern Catskills, southern Greens, Taconics and Helderbergs, we
introduced patchy frost to the forecast. If confidence increases
that frost will develop in areas where the growing season has
started, we will issue a frost advisory. Our Hazardous Weather
Outlook continues to discuss this potential.
Thursday will be a beautiful day. Temperatures finally warm
into the mid to upper 60s under plenty of sunshine as the strong
area of high pressure upstream continues to track eastward
towards our area. Northwest winds will also be lighter,
sustained generally only between 5 and 10 kts. Mostly clear
skies stay in place overnight as high pressure moves overhead
resulting in a seasonably chilly night. Overnight lows drop
into the low to mid 40s.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
A broad, but weak upper level trough will be located over the region
for Friday into the weekend. Although forcing will be somewhat
limited, there will be a threat for showers each day, mainly during
the afternoon and early evening hours. Activity looks fairly
scattered in coverage, so not all locations will see rainfall. There
may be some minor amounts of instability in place, so can`t rule out
a few rumbles of thunder, but coverage looks too low to include this
far out. With a partly to mostly cloudy sky in place, daytime temps
should reach near 70 for Friday through Sunday in valley areas. High
terrain areas look to reach the low to mid 60s. Overnight lows
should mainly be in the 40s, so no threat for any frost/freeze
conditions at this time.
For early next week, there may be a brief period of some ridging for
Sunday night into Monday before the next system approach form the
Midwest. The timing/exact track of this next storm is still
uncertain, but a period of rain or widespread showers is possible
closer to mid-week. Temps will continue to be close to seasonal
normals for mid May.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Clouds are dissipating this evening with the loss of diurnal
heating, but they will expand into the area again from north to
south at and shortly after midnight as another disturbance
rotates in from the north. VFR to high end MVFR levels for a
time roughly 09-13Z (slightly longer at KPSF with upslope
conditions). A couple of showers cannot be ruled out either as
we will place VCSH for KGFL-KPSF-KALB. Cloud bases will rise
again to VFR levels after 13-14Z as diurnal heating commences,
with SCT-BKN coverage returning once again.
Winds will remain around 10 kt tonight from the west-northwest.
Winds will shift more to the north/northwest after sunrise
Wednesday at around 10-15 kts with gusts near 20kts.
Outlook...
Tuesday Night: Low Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Breezy. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Moderate Operational Impact. Scattered SHRA.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Moderate Operational Impact. Scattered SHRA.
&&
.FIRE WEATHER...
West to northwest winds will gust to around 25 mph tomorrow...
After a chilly and breezy day with hit and miss showers,
chances for showers increase later tonight, especially in the
higher terrain where rain may even change to snow showers in
parts of the Adirondacks and southern Greens. The cool and
breezy conditions continue tomorrow with additional scattered
showers possible, especially in southern Vermont. High pressure
builds in for Thursday providing us with plenty of sunshine and
warmer weather.
Maximum relative humidity values tonight rise to 80 to 100
percent. Then, relative humidity values drop tomorrow afternoon
to a minimum between 35 to 50 percent. Overnight maximum
relative humidity values Wednesday night then reach to 85 to 100
percent.
Winds tomorrow will be west-northwest once again and rise to 8
to 18 mph with gusts up to 25 mph. Winds then gradually weaken
Thursday night and drop below 5 kts.
&&
.HYDROLOGY...
Without any appreciable rainfall expected through the end of the
work week, river levels are expected to remain steady or
gradually fall.
For details on specific area rivers and lakes,
including observed and forecast river stages and lake
elevations, please visit the Advanced Hydrologic Prediction
Service /AHPS/ graphs on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Speciale
NEAR TERM...BGM/Speciale
SHORT TERM...Speciale
LONG TERM...Frugis
AVIATION...BGM/Thompson
FIRE WEATHER...Speciale
HYDROLOGY...Speciale
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
654 PM CDT Tue May 11 2021
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...The conv coverage to the north of the RGV is on the
increase as the cold front continues sagging southwards toward the
region. The latest CAMS guidance continues to crank up the conv
over the western counties several hours from now with this conv
complex pushing SE through the RGV as the cold front moves slowly
into the region increasing the surface convergence. SPC is
maintaining a slgt risk for svr conv throughout the night into Wed
morning and will continue to reflect this in the 00Z TAF issuance
for the RGV. Although the next few hours will likely see VFR
conditions prevailing for the area, the aviation conditions will
degrade pretty steadily later tonight through Wed morning as the
conv moves into the region. Expect MVFR conditions to prevail
later tonight with periods of IFR conditions as the stronger conv
moves closer to the RGV airports.
&&
.PREV DISCUSSION... /issued 239 PM CDT Tue May 11 2021/
SHORT TERM (Now through Wednesday Night): Heres what we know.
There will be a cold front dropping into the CWFA overnight
tonight, which will likely bring strong to severe thunderstorms
and subsequent beneficial rainfall for much of the area through
Wednesday evening. The strongest storms will be capable of
producing strong to severe wind gusts, severe hail, as well as
torrential rainfall and gusty winds. Most of that stronger
activity should clear the area by Wednesday afternoon with any
lingering precipitation coming in the form of showers, with
perhaps a rumble of thunder or two through Wednesday evening. The
shower and storm activity expected through the short term will
ultimately keep high temperatures Wednesday afternoon and low
temperatures late Wednesday night several degrees below seasonal
normals.
Heres what we are still pinning down. The timing/onset of
convection in the BRO CWFA continues to be a source of uncertainty
that is causing this forecaster to have a less than ideal time.
Storms could potentially enter the northern edge of Zapata and Jim
Hogg counties as early as 9-10 PM per latest HRRR and GFS
guidance, around midnight per the NAM 3km and ECMWF solutions, or
some time closer to 4-5 AM per the NAM 12km solution. Have
targeted the later solutions for this forecast package given
recent performances between the models. Regardless, a nocturnal
convection event appears likely, which will then spill over into a
more prolonged rain event for Wednesday. Pay close attention to
updates from your friendly neighborhood Warning and Forecast
Office this evening!
LONG TERM (Thursday through Tuesday): Rain chances will diminish
across deep south Texas Thursday into Thurs night as drier air
filters into south Texas in the wake of the 500mb trough across
the east-central United States moving eastward. Isolated showers
and thunderstorms are progged to develop across portions of the
Rio Grande Valley Friday as a weak disturbance in the westerly
flow aloft approaches the CWA from the west Fri afternoon. A
better chance of showers and thunderstorms is expected across the
Rio Grande Valley and northern ranchlands on Saturday as a 500mb
shortwave trough across southwest Texas moves eastward and low to
mid level moisture increases ahead of the upper level feature.
Rain chances are expected to linger through the rest of the
weekend before a 500mb shortwave ridge develops across southwest
Texas Monday providing subsidence in general across the area.
MARINE (Now through Wednesday Night): Generally moderate winds
and seas prevail in advance of the overnight front. Showers and
thunderstorms can be expected across much of the lower Texas
coastal waters for Wednesday which may create localized hazardous
conditions. Northeasterly winds then increase behind the front,
which will likely push winds into Small Craft Exercise Caution
criteria across much of the waters to cap off the short term
marine forecast.
Thursday through Sunday: Moderate to strong northeast winds will
develop across the coastal waters Thursday as high pressure across
the eastern United States and low pressure across the western
Gulf of Mexico increases the pressure gradient across the
northwest Gulf. Winds will veer to the east-northeast and
diminish Friday as the surface ridge begins to move eastward and
the pressure gradient weakens across the western Gulf. Light to
moderate east-northeast winds will veer to the east-southeast and
increase slightly Saturday as low pressure develops on the lee
side of the Rockies. Winds will veer to the southeast on Sunday
with low pressure across New Mexico and a surface ridge across the
southeast U.S. extending into the Gulf of Mexico.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 77 78 70 79 / 40 60 20 30
BROWNSVILLE 77 80 69 81 / 40 70 20 40
HARLINGEN 77 79 67 80 / 40 70 20 30
MCALLEN 76 77 67 81 / 60 80 20 30
RIO GRANDE CITY 74 76 66 82 / 70 80 20 30
SOUTH PADRE ISLAND 76 77 72 75 / 40 60 20 30
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
Short Term/Aviation...60-Speece
Long Term/Upper Air...69-Farris/65-Soria
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1006 PM CDT Tue May 11 2021
.UPDATE...
Storms have weakened across our CWA and we have allowed the Severe
Thunderstorm Watch to expire.
&&
.PREV DISCUSSION... /ISSUED 917 PM CDT Tue May 11 2021/
UPDATE...
The severe threat has ended north and west of I-35 and we have
canceled the Severe Thunderstorm Watch across this area. There is
still a chance for isolated severe thunderstorms east of I-35 and we
will allow the watch to continue. Most remaining convection has
weakened and this trend will continue over the next few hours.
PREV DISCUSSION... /ISSUED 656 PM CDT Tue May 11 2021/
AVIATION...
Short term concern is the ongoing convection across the region.
Currently storms in the vicinity of SAT and SSF. Storms will be
possible for the next several hours in the San Antonio and Austin
areas. Strong gusty winds will be the biggest impact from storms with
gusts up to 25 kts possible. Ceilings will also lower to MVFR in
storms. Otherwise ceilings will be VFR until later this evening when
they will lower to MVFR and later to IFR. Ceilings will stay IFR
through the morning Wednesday and lift only to MVFR during the
afternoon.
At DRT, there may be showers for the next few hours, but otherwise
will be VFR. Ceilings will drop to MVFR overnight. There is a chance
for TS overnight which could drop conditions to LIFR, but
probability is low.
PREV DISCUSSION... /ISSUED 347 PM CDT Tue May 11 2021/
UPDATE...
We have issued a Severe Thunderstorm Watch most of South Central
Texas. Conditions are favorable for the formation of severe
thunderstorms capable of producing hail up to two inches, wind gusts
up to 70 mph, and a tornado or two. The watch is in effect until 10
pm this evening.
PREV DISCUSSION... /ISSUED 251 PM CDT Tue May 11 2021/
SHORT TERM (Tonight through Wednesday Night)...
A diffuse frontal boundary from west to east across south-central
Texas will eventually push south this evening, likely aided by
storms that are expected to increase in coverage and move eastward
across the region later this afternoon through the evening hours. At
19z, areas south of the front were mostly sunny with temperatures in
the 80s to near 90 and dew points in the 70s, while north of it
temperatures were in the 60s and low 70s with some light fog and low
stratus. Temperature gradient from La Grange to burnet is nearly 30
degrees!
An approaching shortwave is already setting off convective
development over the SDB mountain range in Mexico, and some WAA
forced elevated storms continue from just east of Sonora
northeastward into the DFW metroplex, with some of that activity now
into our region from Kerr to Burnet counties although with little
thunder until you cross into Lampasas. In addition, a weak
convergence axis stretches from north of Bryan, TX to near Gonzales
although convective development in our area has been minimal at best.
Even in the cool sector, elevated CAPE in excess of 2000 J/kg exists
above the inversion with steep lapse rates at mid-levels on the
order of 7.8-8C/km. And SBCAPE has been able to build to 2500-4000
J/KG in the warm sector today. Deep layer shear is a little weaker
today, but still decent west, with the special DRT sounding this
afternoon showing 34 knots 0-6km. As the storms in Mexico slowly
enter the area this evening, they will pose the greatest risk for
large to very large hail and a very low chance for an isolated
tornado south of the front where SRH could briefly increase. Any
supercells will likely quickly grow upscale though.
HRRR still hones in on some storms east of I-35 along the existing
convergence axis this afternoon and isolated severe hail or a brief
downburst could be possible there if storms are able to develop
which appears 50/50 at best. Storms are likely to grow into a SW/NE
oriented quasi-complex through the evening hours and pose a marginal
to slight risk of large hail or damaging winds. There is also a low
chance for isolated flash flood impacts with rainfall amounts of up
to three inches in spots which could occur over already saturated
ground. Flash flood guidance is lowest today from San Antonio west
and southwest to the Rio Grande so those will be the areas to watch.
Severe threat should mostly end by midnight at the latest. Some
lingering showers and storms may remain behind the front but
coverage should decrease quite a bit after midnight.
We have kept some low chances of showers and a few thunderstorms in
the forecast through much of Wednesday as some weak isentropic lift
in conjunction with weak elevated instability could lead to isolated
activity at times, especially near the Rio Grande in the AM.
Coverage will be low, and impacts are generally not expected. Skies
will remain cloudy through the day, and it will be quite cool for
this time of year with highs in the low to mid 60s north and low to
perhaps mid 70s south. In fact, Bergstrom will likely flirt with
record low maxT tomorrow. Wednesday night lows should fall into the
50s and lower 60s with any remaining shower chances relegated to far
southwestern portions of the region overnight, if at all.
LONG TERM (Thursday through Tuesday)...
A northwest to west flow aloft is forecast to prevail Thursday and
Friday. Surface winds are expected to turn from northeast to east
on Thursday for most areas with southerly winds returning across the
entire area by midday on Friday. A warming trend is on the way with
highs in the 70s on Thursday and upper 70s to mid 80s on Friday.
Clouds are expected to linger for most of the morning period and
scattered mid to late afternoon both Thursday and Friday.
Showers and storms return across south central Texas on Saturday as
several mid to upper level short waves move from west Texas into
central Texas. The activity diminishes late Saturday night through
early Sunday morning, however, picks up on Sunday as another short
wave traverses across the Southern Plains.
The wet period continues into early next week as the parade of
short waves continue to push over the area. Better chances for rain
come on Tuesday areawide as an upper level system travels across the
four corners region and opens as it moves over the Southern Plains.
The GFS solution pushes a cold front across the area during that time
frame while the ECMWF and CMC models keep a surface southerly flow
through the extended forecast. Time will tell.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 62 67 58 75 57 / 70 30 - - 0
Austin Bergstrom Intl Airport 62 68 57 75 56 / 70 30 - - 0
New Braunfels Muni Airport 63 69 59 77 58 / 60 40 - - 0
Burnet Muni Airport 58 65 55 73 56 / 50 20 - 0 0
Del Rio Intl Airport 66 70 63 77 64 / 60 50 20 - -
Georgetown Muni Airport 60 66 57 74 56 / 70 30 - 0 0
Hondo Muni Airport 65 71 59 77 59 / 50 30 10 - 0
San Marcos Muni Airport 62 68 57 76 56 / 60 30 - - 0
La Grange - Fayette Regional 65 70 60 77 59 / 60 40 10 - 0
San Antonio Intl Airport 64 70 60 75 59 / 70 30 - - 0
Stinson Muni Airport 64 72 61 77 61 / 60 30 - - 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Platt
Long-Term...05
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
620 PM MDT Tue May 11 2021
.DISCUSSION...(This Evening Through Tuesday)
Issued at 133 PM MDT Tue May 11 2021
19z surface analysis had weak high over the upper Midwest with
weak trough from central MT into central WY. Modest return flow
over the CWA per southeast winds. Water vapour had weak mean
trough from central AB into CO. Multiple embedded shortwave
disturbances noted over southeast MT, southern AB, and southern
WY/northern CO. 100-400J/kg MLCAPE noted over northeast WY into
the Black Hills with well-defined CU field in steep low level
lapse rate regime. Best showers currently on the convergence zone
just north of the Black Hills, but latest 0.5km visible satellite
trends suggest expansion of shra/isolated ts will continue this
afternoon, persisting into the early evening hours per HRRR
guidance. Wouldn`t be surprised to see some small hail with the
strongest cells as well as peppy SHSN over the highest elevations.
Activity will wane later this evening as diurnal insolation
ceases and boundary layer stabilizes. Lows tonight will be near
guidance.
Wednesday, mean upper trough shifts slowly eastward in response to
upper ridge building into the western CONUS. Better piece of
energy over southern AB will slide southeast into the northern
plains pushing the surface trough through the CWA. This will be
the focus for shra/ts activity given convergence along front and
interaction with Black Hills terrain. Generally less than 500J/kg
MLCAPE will be available, but small hail still possible. Modestly
gusty southerly winds expected ahead of the trough. Temperatures
Wednesday will be near guidance.
Thursday/Friday, western CONUS upper ridge shifts east and flattens
leading to west/northwest flow aloft with embedded shortwaves and
weak instability. Diurnally driven shra/ts expected with peak hours
diurnally driven during the late afternoon/early evening hours.
Temperatures will slowly warm given thermal ridge expansion.
The weekend in early next week, upper low will probably break off
in the west and then spin into the southwest CONUS. A series of
disturbances will affect the CWA with daily chances for
showers/storms. Temperatures will be near/slightly above normal.
Typical mid-May weather.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 620 PM MDT Tue May 11 2021
Showers and isolated thunderstorms will continue this evening,
mainly across the northern Black Hills. Areas of MVFR conditions
(and localized IFR in the Black Hills) are possible with the
heavier precipitation. Precipitation will wane early this
evening. Otherwise, VFR conditions are expected through the
forecast period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Helgeson
AVIATION...13