Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/24/19
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1013 PM CDT Fri Aug 23 2019
Finally had enough clarity to update the forecast for the rest of the
night through 12Z Saturday. A combined sea-breeze and outflow from
storms on the coastal plains pushed all the way to the Edwards
Plateau and Rio Grande Plains late this evening. This has re-
invigorated convection, but already the bump seems to be past the
peak and we expect convection to decrease over the next few hours.
That said, areas with storms in the vicinity now can expect a bit
more rain before midnight, then a fairly quick tapering off.
Otherwise, the rest of the forecast is in good shape, but we still
re-trended hourly variables through 12Z.
.PREV DISCUSSION... /ISSUED 653 PM CDT Fri Aug 23 2019/
00Z Aviation forecast below.
Isolated to scattered SHRAs and TSRAs ongoing across portions of
South Central Texas this evening. Activity near and east of the I-35
corridor should diminish after sunset. Convection across portions of
the Hill Country and near the Rio Grande could persist longer into
the evening, before diminishing overnight. A few storms could produce
gusty winds. In addition, outflow from earlier storms, combined with
the sea-breeze boundary, is racing inland and producing strong wind
gusts at AUS, HYI, and BAZ and should arrive at SAT very shortly.
Wind gusts between 25-40 kts have been recorded with this boundary.
Outside of convection VFR conditions will prevail through the evening
and most of the overnight. A small area of MVFR ceilings may occur
between 09Z-15Z near the I-35 corridor.
PREV DISCUSSION... /ISSUED 250 PM CDT Fri Aug 23 2019/
SHORT TERM (Tonight through Saturday Night)...
Early afternoon water vapor imagery showed a few larger scale
features around the continental US with a compact upper low spinning
over Montana, Wyoming, and Idaho and a shortwave trough axis located
over the northwestern Gulf of Mexico. Additionally, regional VAD
wind profilers indicate that the mid-level trough that was evident
over West Central Texas on this morning`s radiosonde observations is
still lingering over West Central Texas. Visible satellite imagery
has shown an enhancement in the cumulus field in the vicinity of this
feature. Continued heating combined with weak lift from this trough
and residual surface boundaries from last night`s thunderstorms will
allow for deeper updrafts to develop through the remainder of the
afternoon hours and into the early evening. This will result in rain
chances focusing in two areas this afternoon: the Hill Country and
parts of the Rio Grande Plains, which are closer to the trough, as
well as the Coastal Plains as the sea breeze moves inland. Surface
dew point depressions around the region are close to 25 to 30 degrees
this afternoon and this relatively dry sub-cloud airmass will mean
that any strong thunderstorm will be capable of a gusty wind threat.
GOES Total Precipitable Water satellite imagery shows that
precipitable water values range from 1.6 to 1.9 inches across the
region this afternoon in a weakly sheared environment and
thunderstorms will also be slow-moving and capable of locally heavy
Regional radars shows a southward-moving outflow boundary nearing
the Interstate 20 corridor as well, which a few HRRR runs have
indicated may reach Central Texas before midnight tonight. Only
carrying a silent 10 percent chance of rain for this feature, but a
mid-evening update to increase rain chances for the Central Texas
counties may be needed should it hold together. Otherwise, storms
may linger into the the early morning hours across Val Verde County
given the proximity of the mid-level trough with a few streamer type
showers edging into the Coastal Plains by dawn. Redevelopment of
nocturnal stratus will again keep overnight lows elevated in the low
to mid 70s.
Broad mid/upper-level ridging spreads across California into the
Desert Southwest tonight as the weak mid-level trough axis remains
centered over Texas. As the closed low near Montana opens up and
crosses the Central Plains during the day Saturday, the weakness over
Texas gets pushed east of the region and and allows for ridging to
begin spreading back into the state Saturday night. This will mean
that isolated to scattered showers and thunderstorms will be possible
across most of the region during the late morning through early
evening hours on Saturday as convective temperatures are reached,
with greatest coverage along mesoscale boundaries either leftover
from storm`s today or the sea breeze. Forecast soundings continue to
indicate an inverted-V profile, indicating stronger cells on Saturday
will once again be capable of gusty winds. While a few storms may
linger into the evening hours Saturday across the Rio Grande Plains,
loss of heating will allow for most activity to dissipate with lows
again in the low to mid 70s.
LONG TERM (Sunday through Friday)...
With mid-level ridging building back into the region on Sunday,
temperatures will gradually get hotter Sunday through the mid-week
period. This will also suppress rain chances across most of the
region save for the sea breeze as it reaches the Coastal Plains. A
series of troughs crossing the Central Plains late week may attempt
to send a cold front into North Texas by late in the forecast, but
inconsistencies amongst medium range guidance precludes introducing
any kind of significant changes to the temperature or rain forecast
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 77 97 78 99 78 / 20 20 10 20 10
Austin Bergstrom Intl Airport 75 95 77 98 78 / 20 20 10 20 10
New Braunfels Muni Airport 75 95 76 98 77 / 20 20 10 20 10
Burnet Muni Airport 74 95 75 98 76 / 20 20 10 20 10
Del Rio Intl Airport 78 98 78 102 79 / 30 30 20 10 0
Georgetown Muni Airport 76 97 77 99 78 / 20 20 10 20 10
Hondo Muni Airport 76 99 76 100 77 / 10 30 20 20 10
San Marcos Muni Airport 75 96 76 98 77 / 20 20 10 20 10
La Grange - Fayette Regional 76 97 77 98 78 / 20 30 10 30 10
San Antonio Intl Airport 77 97 78 98 79 / 20 20 10 20 10
Stinson Muni Airport 77 97 78 98 79 / 20 20 10 20 10
Area Forecast Discussion
National Weather Service Memphis TN
729 PM CDT Fri Aug 23 2019
Updated to lower rain chances across the north tonight.
Radar trends are showing a gradual decrease in storm coverage
this hour...with no activity currently across the northern two
thirds of the County Warning Area. Have lowered rain chances this
evening and later tonight in this region...with the southwest
delta counties favored for continued overnight activity.
.PREV DISCUSSION... /issued 648 PM CDT Fri Aug 23 2019/
DISCUSSION... /issued 301 PM CDT Fri Aug 23 2019/
Main story this forecast is the continued unsettled pattern
across the Mid-South, with periods of showers/storms. Pinpointing
timing and location of most concentrated precip will be
challenging given generally weak flow and features. Diffuse
surface front should move south into our southern counties today.
Guidance is consistent in bringing a weak upper system across the
area tonight and Saturday. With moist airmass and fairly light
winds, will add patchy fog toward daybreak Saturday. Lift from
upper system and focusing of surface front should result in
greatest precip coverage south of I-40 corridor tonight and
Saturday. System should move east of CWA Saturday evening, with
lower precip chances Saturday night.
Another weak system to move across the Mid-South Sunday. A somewhat
stronger disturbance associated with upper low over MO/IA should
move across the area by Sunday evening, bringing another round of
precipitation late Sunday and Sunday night.
Monday-Wednesday, Mid-South will be under generally broad WNW flow
aloft. The series of weak upper systems will continue, with GFS and
ECMWF showing disturbances moving across the area every 18 hours or
so. By Thu-Fri, both ECMWF and GFS amplify the NW flow aloft and
bring a cold front through the area with drier air moving in.
00Z TAF Set
An outflow boundary from convection occurring across N MS may
move through KMEM around 01Z. Some convection has developed behind
the boundary. The HRRR continues convection through 06-7Z. For
now will just continue with VCSH wording through 07Z. Models still
show some IFR conditions spreading into the Mid-South between
09-12Z. New convection will then start developing around 18-19Z
with the HRRR focusing development near the MS/TN border. For now
will continue VCTS wording at KMEM, KMKL, and KTUP. Winds will
remain out of the NE at 5-10 KTS through period. Although, speeds
may diminish during the overnight hours.
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
936 PM EDT Fri Aug 23 2019
A cold front will approach the area tonight and slowly cross
the region Saturday. The front will stall well offshore Sunday
with low pressure moving along it Monday. Another cold front
will approach the area mid to late week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 930 PM Friday...Convection has focused across the nrn tier
just ahead of front as expected. Instab is diminishing and this
shld end severe threat...however locally very heavy rain will
cont for at least next few hrs with flood threat. Did signif
lower pops srn tier for next few hrs as will only see some
sprinkles from mid lvl debris clouds. Convection may spread S
late tonight with front however HRRR show little remaining late.
Prev disc...Immediate next few hours are expected to be mainly
dry with a few afternoon showers and storms possibly sneaking
into the coastal plain. Main event is later tonight as the front
sinks south and storm coverage increases in an axis of 30-35
knot 0-6 km bulk shear across the NC/VA border and MLCAPEs
approaching 2500 J/kg. All the hi-res guidance indicates a
squall line developing and stalling along the VA border before
progressing south after sunset as the convective system becomes
gradually cold-pool dominant. Main concern is minor/urban
flooding with PWATs of 2-2.25 inches, but current thinking is
line will be moving fast enough to preclude more widespread
flash flooding. A risk for gusty to severe winds with the squall
line is possible mainly for our northern tier of counties.
Overall precipitation chances drop to the south with much weaker
shear and lack of daytime heating. Have categorical PoPs
northern tier to high chance along the Crystal Coast.
Highs remainder of today top out in the low 90s with cloud cover
keeping lows in the mid 70s along the coast, to low 70s inland
with the aid of cooling rainfall.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
As of 300 PM Friday...Front continues to push south towards the
coast on Saturday with plenty of cloud cover lingering in its
wake. Behind the front, high pressure to the north will shift
east and set up a weak wedge/cold-air dam to our west, aiding in
cooler and more stable air. A thin axis of instability is
possible along the coast as hinted by hi-res guidance, but given
the expected considerable cloud cover I have my doubts if there
will be enough instability to sustain as aggressive of coverage
as advertised. If more sustained activity is realized storm
motions will be slow in an axis of 2-2.25 inch PWATs suggesting
a localized flooding threat, especially considering the recent
substantial rainfall these areas have received. Due to
uncertainty in storm evolution, nudged PoPs down from
categorical to likely. With the wedge and plenty of cloud cover
lows tomorrow will be considerably cooler with low to mid 80s
along the coast, upper 70s in the northern coastal plain.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
As of 345 PM Fri... Periods of unsettled weather continues
Sunday and possibly into Monday. Another cold front will
approach the area from the west by midweek.
Saturday Night...Cold front will push offshore by Sat night. As
the front pushes south, a weak/shallow high pressure wedge
builds in to the Carolinas. Fairly widespread showers will
continue through the evening, as decent overrunning regime sets
up with H85 mb flow still srly. PW values are above 2.00" and
deep warm cloud layer with the best convergence near the
low/mid level frontal across srn half of the FA.
Sunday through Monday...Continued following the more consistent
ECMWF, as has support from the UKMET/CMC with a more developed,
albeit further offshore, tropical system. The GFS appears to
remain an outlier with a near-coast and much weaker tropical or
subtropical system. With expected further offshore track,
impacts would be relegated to the waters in the forms of high
surf and strong rip currents. Gusty winds will be felt along the
coast due to high pres ridging into the Carolinas and low pres
gathering to the south. More unsettled weather possible for
Sunday, though coverage and intensity does not appear too
impressive, so rain amounts do not look too high, even along
coastal areas. Will retain likely pops for coastal zones with
chc pops interior as ocnl showers will be a threat at any time
during the day. The low will pass well east of the NC coast on
Monday, keeping only chc showers in the fcst, and breezy
conditions on the coast due to gradient between high pres
ridging in from the west and the low well offshore.
Tuesday through Thursday...High pressure should build back in Tue
with more drier conditions, then an approaching cold front by
midweek resulting in sct showers and thunderstorms. Expect
highs to climb back towards climo, in the mid/upr 80s. Lows
continue in the 60s interior to low 70s coast.
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Short Term /through Saturday/...
As of 645 PM Friday...VFR conts and shld thru evening outside
poss brief sub VFR if shra/tsra impact a terminal. Later tonight
as front pushes thru most of guidance suggests IFR cigs develop
N to S after 06Z that will cont thru Sat Morn. Later Sat have
cigs lifting a bit to MVFR but confidence low as IFR could
persist in the moist NE flow. Numerous shra and a few tsra
expected to develop again Sat as well.
Long Term /Saturday night through Tuesday/...
As of 345 PM Fri...The frontal boundary will remain close to
the NC coast and continue bring unsettled weather Sat night and
into Sun, with ocnl sub VFR expected. Some drier air moves in by
the beginning of the week leading to improved flying conditions.
Short Term /Tonight and Saturday/...
As of 930 PM Friday...Strong SW winds ahead of front over
mainly Pamlico Sound are finally showing signs of diminishing.
This trend shld cont as front slowly pushes S into the area
Prev disc...Seas this hour 2 to 3 feet except for more
persistent 4 foot seas in the outer waters with SW winds at
around 10 to 20 knots. A cold front will approach the northern
waters tonight with SW winds at around 15-20 knots with a few
gusts to 25 knots, although nothing widespread enough to warrant
SCA. Winds gradually shift to the N and then NE through
Saturday as the front slowly pushes offshore. A weak surge of
N/NNE winds mainly for the northern waters and sounds at around
15 knots is expected Saturday afternoon and evening.
Long Term /Saturday night through Tuesday/...
As of 345 PM Fri...A cold front will be south of the waters by
Sat night. Winds increase out of the NE on Sunday and should
reach SCA conditions with sustained 20-25 kt NE winds due to
high pres from the west and developing low pres well offshore.
The gusty NE winds continue on Monday as potential tropical or
subtropical storm moves NE well off of the NC coast. Seas and
swell will build to greater than 6 ft by Sunday and remain that
way through Monday as the system tracks NE. WWIV much too low
with the waves so relied more on the ECM waves and NWPS. Winds
and seas start to subside later Monday through Tuesday as the
system moves well away from the waters.