Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/11/21
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
638 PM CDT Sun Oct 10 2021
The cold front/dryline is currently along a line from near Abilene to
San Angelo to near Dryden. High-res model guidance is in fairly good
agreement that the front will move into the Hill Country around 9 PM
continuing to move southeast into the I35 corridor around midnight
and into the eastern counties by 2 AM. As of now, convection along
the boundary to our north continues to struggle as strong capping
looks to be winning out. As the large scale forcing increases later,
this cap may erode to allow for some surface based convection and the
latest runs of the HRRR show this to occur in the Hill Country with
the activity possibly weakening as it moves east and nears the I35
corridor as CIN likely increases once again. However, the
thermodynamic environment could allow for a strong to severe storm or
two when storms initially develop and possible for 2-4 hours beyond
that before the atmosphere stabilizes. The main risk for this
activity will be hail and damaging winds, but can`t rule out an
isolated tornado especially in the northern Hill Country where storms
initialize before things go more linear given some expected curvature
on forecast hodographs.
Cold front/dryline remains northwest of DRT and AUS at the present
time. The boundary will arrive to AUS and SAT around 4-5z and the
best chances for any showers or thunderstorms will be at AUS. Will
mention a TEMPO group there for thunder, and a VCSH for SAT where the
activity is expected to be weaker and more scattered. Northwest winds
will quickly move in behind the boundary with VFR conditions expected
for the rest of the night and tomorrow.
.PREV DISCUSSION... /ISSUED 301 PM CDT Sun Oct 10 2021/
SHORT TERM (Tonight through Monday Night)...
Warm, humid and breezy conditions prevail across South Central Texas
this afternoon. A cold front was dropping southward across Northwest
Texas. As the associated mid and upper level shortwave races east
out of the the Panhandle and into Oklahoma and Kansas this evening,
the cold front will drop south, reaching the southern Edwards
Plateau, northern Rio Grande, and Hill Country mid to late evening
and into the I-35 corridor around or after midnight.
AMDAR data early this afternoon out of AUS and SAT confirms a cap
around 850mb is in place. However, forecast soundings indicate the
inversion will try to erode away roughly near and north of I-10 just
ahead of the front later this evening. As this happens convective
allowing models are in general agreement with a development of a
line of showers and embedded thunderstorms as the front reaches
deeper moisture across the Hill Country and the I-35 corridor, again
primarily near and north of I-10. The farther southwest of I-10 the
stronger the convective inhibition will remain intact.
Instability and deep layer shear parameters will be sufficient for
the potential of a few of these storms to become strong to severe,
conditional on where the cap erodes. The main threats will be hail
and damaging straight-line wind gusts. HREF guidance indicates as
you get farther east of I-35 and south of I-10, towards the Coastal
Plains, that the instability and shear parameters will weaken
overnight. Convective allowing models do show a weakening trend into
the early morning hours across this region. SPC currently has a
Marginal Risk for severe storms roughly near and north of a
Vanderpool to New Braunfels to La Grange line, and a Slight Risk for
severe storms clipping northern Burnet, Llano, and Williamson
counties. But as has been advertised, the better dynamical forcing
and severe weather parameters will remain well to the north of the
CWA. Rainfall amounts near and north of I-10 are generally forecast
to be less than 1/2 inch, with isolated amounts of up to about an
A few showers could linger across the Coastal Plains after sunrise
Monday morning, however the majority of the area should see drier
and slightly cooler conditions and clearing skies Monday. This will
be temporary as a low level return quickly sets back up Monday
night, along with the possibility of a few showers developing
overnight and into Tuesday morning.
LONG TERM (Tuesday through Sunday)...
A very wet pattern is taking shape for the periods from late Tuesday
through late Friday. An upper low that deepens over the 4 corners
region Tuesday will enhance onshore low level winds and begin to
generate some streamer convection as Pwat values climb to near 2.0 in
some locations. Conditions should continue to deteriorate Tuesday
night into Wednesday morning with an axis of elevated Pwat values in
the 2.0 to 2.3 inch range taking shape over I-35 by 12Z Wednesday.
A tropical connection is made with what should be Tropical Storm or
possibly Hurricane Pamela by this time, and the tropical cyclone will
likely be making an approach toward the mountainous coast of Mexico
by this time as well.
By 00Z Thursday a broad, nearly stationary upper trough draws in the
moisture and dynamics from the tropical system steadily, with the
pattern not easing up until a cold front makes its way into Central
TX by midday Friday. Model consensus of QPF values project the
period of heaviest rainfall to occur from 06Z Thursday through 12Z
Friday, but as we`ve often seen with this type of heavy rainfall
pattern, the emergence of stronger lift may occur early as the
moisture interacts with the entrance region of an upper jet. Thus
there could be a steady training of convection over the I-35 corridor
from 06Z Wednesday through 18Z Friday. Storm totals currently depict
around 3 to 4.5 inches over this area, but as we get closer to the
actual event, finer resolution models may begin showing pocket of
enhanced precipitation areas in excess of 8 inches.
The tropical depression 16-E, is still not fully developed yet so
there remains some uncertainty over how much dynamics will be pulled
across TX. However the general track of the dynamics is coming into
good alignment among the deterministic runs. This increases the
confidence of a significant rain event over the I-35 corridor as a
general location, and later updates can be tailored to how much water
is expected. MEX guidance for San Antonio is now showing 100 percent
for Thursday night.
In the wake of the heavy rain threat late Friday, the first fall
front to bring drastic temperature changes finally arrives for a
chilly weekend. Little to no overrunning of moisture over the front
is projected at this time. Weekend high temperatures are expected to
be held to mainly 70s.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 65 86 71 90 75 / 80 0 10 40 20
Austin Bergstrom Intl Airport 64 86 70 90 73 / 70 0 10 30 20
New Braunfels Muni Airport 65 87 71 92 74 / 70 0 20 30 20
Burnet Muni Airport 60 84 69 87 73 / 80 0 10 40 20
Del Rio Intl Airport 64 90 73 93 75 / 10 0 - 20 40
Georgetown Muni Airport 61 85 69 88 73 / 80 0 - 40 20
Hondo Muni Airport 65 88 72 93 74 / 20 0 20 30 30
San Marcos Muni Airport 65 86 70 91 73 / 70 0 10 30 20
La Grange - Fayette Regional 68 87 73 92 75 / 70 10 10 20 10
San Antonio Intl Airport 67 86 73 91 75 / 60 - 20 30 30
Stinson Muni Airport 70 88 75 94 77 / 50 - 20 30 20
Area Forecast Discussion
National Weather Service Grand Forks ND
1023 PM CDT Sun Oct 10 2021
Issued at 1010 PM CDT Sun Oct 10 2021
Updated sky cover just a bit for a tad faster clearing eastward
trend. Clearing is near Langdon-Lakota-Valley City and Forman
moving steadily east albeit slowly. By 12z clearing is expected to
be near a Hallock-Thief River Falls-Wadena line. The deformation
zone rain band on west side of upper low is diminishing as
anticipated and the scattered showers dissipated too over MN,
exception over Lake of the Woods where rain showers continue on
west side of t-storm area in Ontario.
UPDATE Issued at 735 PM CDT Sun Oct 10 2021
500 mb low is moving slowly east thru northern MN and was near
Bemidji at 00z. Backedge of clouds was just west of Cando-Devils
Lake-Jamestown and moving slowly east and is progged to be just
east of the Red River at 12z. The showers in NW MN are reducing in
number but there is still a def zone band of light rain moving
back east as the upper low departs. It is forecast to slowly
weaken the next few hours as it moves slowly east.
.SHORT TERM...(This evening through Monday night)
Issued at 311 PM CDT Sun Oct 10 2021
Short range concerns remain focused on the brief window for severe
thunderstorms in north central MN through 6PM and lingering
rainfall into the evening/overnight.
Vertically stacked/occluded upper low remains over our CWA, with
deformation zone rain band in our west, clusters of showers still
rotating around the center, and more organized convection to our
east. Better lapse rates/instability and effective shear have also
remained east of our forecast area so far today where more robust
CU/updrafts have formed. However, RAP still shows the axis of
instability and better shear wrapping into our far northeastern
counties over the next 3hr and there is at least some TCU developing
into northwest MN where breaks in stratus have been occurring. Due
to the potential for higher shear even modest instabilty will be
enough to support low top supercells. The threat may remain more
isolated though in our northeast counties (Beltrami/Lake of the
Woods) and the window narrow (basically 3-6PM). Potential low top
supercells in the expected environment raises the potential for hail
to 1", winds to 60 mph, and brief tornadoes.
The upper low should start to pick up its motion eastward and
showers should slowly exit west to east through the evening, with
further reductions in coverage/intensity with sunset and loss of
daytime heating. Any lingering rain overnight would be associated
with remnants of deformation band, but amounts would be much lower
after the afternoon/evening period. Where showers train or
thunderstorms track this afternoon/evening additional rainfall as
high as 1" can`t be ruled out, though current means/consensus are
generally remain under 0.25".
Monday-Monday night: Shortwave ridging and west-northwest BL flow
should result in clearing skies, along with, mild and dry conditions.
Expect seasonal highs in the 60s for most locations (possibly a
little lower further west (upper 50s). Cloud cover should limit
diurnal cooling some, so while a few locations may reach the mid
30s, most should remain around 40 or a bit warmer despite cooler
.LONG TERM...(Tuesday through Sunday)
Issued at 311 PM CDT Sun Oct 10 2021
Main challenge for this period is a developing system and potential
impacts for the latter half of the work week.
Return flow at the surface on Tuesday will moderate temperatures a
bit but no significant warming is expected. Otherwise, the upper
level trof over the intermountain west digs in and deepens as a
series of disturbances rotate into the base of the trof.
Wednesday through Thursday...the system becomes much more organized
and has a good influx of moisture to feed it. The system is
projected to lift north with rain spreading out ahead of it, as is
typical of a fall type regime. The cold upper low will bring more
seasonal temperatures, and the relatively slow movement of the
system will result in precipitation continuing into Thursday night
or early Friday. As the trough departs east, colder air lingers and
there is the potential for widespread frost across the region as
high pressure settles across the region. Otherwise, the upper
pattern shifts and the upper trof moves a little more quickly
towards the Great Lakes, with the ridge rebounding over the area
bringing warmer temperatures to end the forecast period.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 735 PM CDT Sun Oct 10 2021
IFR ceilings over most of the RRV and into MN on the backside of
the departing upper low. Expect gradual improvement over E ND as
clearing works east with IFR going to MVFR/VFR overnight. IFR
likely most of the night if not all TVF and BJI.
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1007 PM EDT Sun Oct 10 2021
Low pressure just off the coast will stall just off Cape Lookout
through tonight, and then meander just offshore tomorrow.
Troughing offshore will persist Tuesday before high pressure
regains control by mid week.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1005 PM Sun...Main surface low continues to meander
roughly 40 nm east of Cape Lookout although a weak mesolow is
attempting to form south of Cape Hatteras with heavier rain on
its north side as convergence is maximized. Adjusted winds and
sky cover based on observational trends, but forecast otherwise
remains in good shape.
Prev disc...An area of low pressure remains stalled about 20
miles off of Cape Lookout this afternoon. Most of the deep
convection has dissipated from the circulation but several areas
of shallow topped showers continue, and periods of rain showers
will persist across coastal areas through tonight. Strong winds
continue across the coast at 20-30 mph, and even farther inland
this afternoon in the form of gusts. Expect winds to remain
strong and even strengthen some as the low continues to slide
towards Cape Lookout overnight.
Widespread cloudiness and rain showers have kept temps fairly
cool so far today, but some breaks of sun this afternoon will
allow temps to climb into the upper 70s especially over the
coastal plain. Tonight, mild temps will continue with lows
ranging from the mid 60s inland to the low 70s across the
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 400 PM Sun...Low pressure will begin to weaken tomorrow
but remain just off the NC coast. This will lead to continued
northerly flow and a decent coverage of showers through the day
as the low levels remain nearly saturated, with the best chances
along the coast. Considerable cloudiness will continue, though
there will be some peaks of sun in the afternoon, and have highs
reaching the mid to upper 70s across the area.
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 240 PM Sunday...A return to benign conditions is expected
by Tuesday persisting through late week into Saturday.
Ridging at the surface and aloft is expected to build over
Eastern NC. Trends remain towards drier and warmer conditions as
high pressure persists over the area lasting through late week.
Highs in the low 80s through most of the week. Overnight temps
will fall into the 60s.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHORT TERM /through Monday Night/...
As of 745 PM Sun...Low to moderate confidence forecast
overnight as surface low continues to swirl offshore and band of
MVFR cigs persist mainly east of EWN, with IFR conditions over
OBX terminals. Expecting cigs to continue lowering tonight with
all sites descending to at least MVFR by 02-03Z. Trickier part
of the forecast is whether IFR will develop. Confidence is
highest at EWN which will be closest to the surface low and axis
of lower cigs, but remains very questionable for more western
terminals. LAMP guidance is very aggressive with IFR
probabilities, but is an outlier with more muted NAM and HRRR
soundings which show cigs flirting around 1 kft. Kept
predominantly MVFR cigs with respect to the well-performing
HRRR, but it is likely to be another night where flight
restrictions fluctuate between MVFR and IFR between
Cigs expected to slowly rise to MVFR tomorrow but remain there
as low-level inversion refuses to break for much of the day.
Resurgence of north-northeasterly winds with gusts to 15-20 kt
LONG TERM /Tomorrow Night through Friday/...
As of 305 PM Sunday...Conditions should improve to VFR late
Monday into Tuesday as the low moves out to sea and high
pressure builds into the region.
SHORT TERM /through Tomorrow/...
As of 1005 PM Sun...All headlines remain intact late tonight.
Gale force gusts have been observed just in the past hour or so
across the Pamlico Sound. Offshore buoys have been close to 35
kt and ASCAT scatterometer data suggests winds of 30-35 kt
continue across the central and southern waters.
Prev disc...A stalled area of low pressure will remain spinning
just off of Cape Lookout through tonight, with strong winds
continuing. There are some indications that winds will briefly
strengthen this evening and into tonight in the immediate area
of the low, and because of this threat, have issued a short
duration Gale Warning for the coastal waters south of Cape
Hatteras as well as the Pamlico Sound. Elsewhere SCAs have been
extended through the night, with conditions improving by
NNEasterly winds on the backside of the low should strengthen to
25-30 kts with gusts 35-40 kts across the southern coastal
waters and Pamlico Sound this evening, while winds remain 20-25
kts with gusts to 30 kts farther north. Overnight the low will
begin to weaken, and winds will become mostly 15-25 kts, and
then subside to NNE 10-20 kts by tomorrow afternoon. Seas will
be slowly subsiding through the period, remaining 6-8 ft through
tonight, and then by tomorrow afternoon will be 5-7 ft north of
Cape Hatteras, and 3-6 ft to the south.
LONG TERM /Monday Night through Friday/...
As of 345 PM Sun...The surface low along the NC coast moves
farther offshore by Monday night, allowing the pressure
gradient to weaken with SCA conditions lingering due to waves
rather than winds. Winds shift northwesterly Tuesday and
diminish to 10-15 kts with seas subsiding from south to north.
Southern waters subside 2-4 ft early Monday, but 4-6 ft lingers
north of Ocracoke Inlet through Monday night. For Wednesday into
Thursday, winds remain northerly to northwesterly at 10-15 kt
with seas subsiding to 2-5 ft, highest north of Diamond Shoals
and farther offshore.
As of 345 PM Sunday...A coastal flood advisory continues for
expected impacts soundside along the southern Pamlico Sound,
Core Sound, and tidal Neuse and Pamlico Rivers and smaller
Strong NNE winds will continue this afternoon and through the
first half of tonight. This will lead to a secondary rise in
water as levels have subsided some from early today. Expected
rises remain in the 1-2 ft above ground level (AGL) range.
Additionally, a few areas of ocean overwash will again be
possible on the Outer Banks with tomorrow morning`s high tide,
with residual strong onshore winds, large waves, and continuing
Kings Tides. A new Coastal Flood Advisory may be issued
overnight for this area of concern.
NC...Coastal Flood Advisory until 7 AM EDT Monday for NCZ094-194-
Beach Hazards Statement from 8 AM EDT Monday through Monday
evening for NCZ203-205.
Coastal Flood Advisory until 3 AM EDT Monday for NCZ080.
MARINE...Small Craft Advisory until 6 AM EDT Monday for AMZ131-136-230-
Small Craft Advisory until 10 AM EDT Monday for AMZ137.
Gale Warning until 3 AM EDT Monday for AMZ135-154-156-158.
Small Craft Advisory until 8 AM EDT Tuesday for AMZ150.
Small Craft Advisory until noon EDT Tuesday for AMZ152.
Area Forecast Discussion
National Weather Service Paducah KY
829 PM CDT Sun Oct 10 2021
Issued at 828 PM CDT Sun Oct 10 2021
Timing of precipitation still appears to be on track into the WFO
PAH CWA toward daybreak. The high resolution deterministic and
ensemble guidance (.e.g, NAMNest, FV3SAR, HRRR, and HREF) still
seem to be doing good on spatial/temporal orientation of the
convection currently in OK.
Leaned closer to GFS based guidance, NAMNest, and HRRR for winds
and temperatures overnight, keeping temperatures slightly
elevated. Adjusted dewpoints slightly toward NBM HRRR guidance to
reflect slower change in dewpoint values.
Overall, forecast appears to be on track from dayshift forecast
.SHORT TERM...(Tonight through Tuesday)
Issued at 300 PM CDT Sun Oct 10 2021
The main concern in the short term is the potential for showers
and thunderstorms on Monday, including some risk for strong to
severe thunderstorms, in addition to strong gusty winds.
Dry and unseasonably warm conditions will persist through much of
tonight as shower and thunderstorm activity develops and largely
remains west of the area. While winds should subside to around 10
mph this evening, southerly winds will increase substantially on
Monday. Sustained winds of 15 to 25 mph will occasionally gust as
high as 30 to 40 mph.
A potent shortwave trough currently over the southern Plains is
forecast to become negatively tilted as it swings northeast into
the lower Missouri and middle Mississippi Valleys on Monday. The
approach and passage of this feature will result in a round or two
of showers and isolated/scattered thunderstorms on Monday.
The potential remains for strong to severe storms on Monday, as
evidenced by model forecasts of strong deep layer shear and at
least marginal surface based instability. However, the brunt of
the strongest activity may remain just north of the immediate area
in closer proximity to the strongest forcing. The midday SPC Day 2
Outlook update has trimmed back the slight risk to northern parts
of southern Illinois and southwest Indiana, with a marginal risk
Expect one more warm night with low temperatures near 70 across
much of the area. Highs both Monday and Tuesday should range from
the upper 70s to lower 80s, with lows Monday night dropping back
into the 50s.
.LONG TERM...(Tuesday night through Sunday)
Issued at 300 PM CDT Sun Oct 10 2021
An active weather pattern is in store for the extended portion of
the forecast. Good agreement continues among the deterministic and
ensemble guidance. By Tuesday night, a highly amplified synoptic
configuration will be in place over the CONUS. A deep longwave
trough will dig into the Four Corners and quickly eject to the
northeast, becoming centered over the Red River Valley by 0z Friday.
At the same time, surface cyclogenesis will commence over the
central Rockies. The surface low will rapidly deepen and move over
the Red River Valley by Friday. A warm front associated with this
low pressure system will lift into the western portions of the
forecast area by early Wednesday morning, kicking off isolated to
scattered light showers or thunderstorms across southeast MO into
southwest IL. This pattern will continue into Thursday, with
occasional light rain showers spreading across southeast MO into
southern IL. PoPs and the potential for locally heavy rain will
increase Thursday night through Friday night as a secondary trough
sweeps through the Midwest, dragging a surface cold front through
the forecast area with it. A moist air mass is progged to surge into
the region ahead of the cold front, with precipitable water values
progged to reach 150-200% of normal values. With precipitation
moving parallel to the front, the potential for training rain
showers and thunderstorms and locally heavy rain will need to be
watched closely. We dry out and cool down for the weekend as
cool/dry high pressure builds into the region.
Temperatures will begin quite warm, with highs in the lower to
middle 80s on Wednesday. As clouds and precipitation increase in
coverage, high temperatures will fall for Thursday and Friday,
reaching the upper 70s/lower 80s and lower to middle 70s,
respectively. A refreshing taste of autumn weather will arrive for
next weekend, with high temperatures in the lower to middle 60s and
plenty of sunshine. For low temperatures, values will fall into the
upper 50s to middle 60s Wednesday through Friday. For the weekend,
low temperatures will fall into the middle 40s to lower 50s.
Issued at 557 PM CDT Sun Oct 10 2021
With the 00z Monday WFO PAH TAF issuance, introduce lower VFR
ceilings and VFR visibility restrictions associated with expected
precipitation with northeast lifting zone of convection Monday
Main focus of the forecast groups was to account for significant
wind gusts after 12z-14z Monday. The exception is for KMVN were
gusts may occur as early as 07z Monday. There is also a marginal
potential for low level wind shear at KMVN. Although confidence is
marginal, kept a mention in the 07z-10z time frame.
Given the uncertainty regarding direct thunderstorms over each
TAF location, kept the mention out with this forecast issuance.
The same applies to lowering visibility below VFR category.