Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/16/22
Area Forecast Discussion
National Weather Service Charleston SC
1044 PM EDT Mon Aug 15 2022
A cold front will move into the region tonight and Tuesday,
lingering in the vicinity through late week.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Late evening SPS mesoanalysis indicates that the forecast area
is covered in at least 50 J/kg of CIN. MLCAPE generally ranged
around 500 J/kg. Based on the latest run the HRRR and regional
radar trends, convection will likely continue to weaken as it
pushes towards the coast. The forecast will continue to feature
mentionable PoPs, with values as high as likely across Berkeley
County. However, the intensity will be lowered below moderate.
Most activity will have diminished or exited the area by
daybreak, but a few showers will remain possible with the front
still in the vicinity. Low temperatures tonight will mainly be
in the lower 70s, except in the mid 70s closer to the coast.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday through Thursday: A weak front is poised to drift into the
forecast area Tuesday morning and help serve as a triggering
mechanism for showers and thunderstorms into the afternoon. Model
consensus favors the coastal corridor for the best coverage and that
is where the highest rain chances have been placed, including a
small area of 50-60 across eastern Berkeley and Charleston counties.
Wednesday is a trickier day as some model solutions show the
boundary shifting offshore and further south. If this were to occur
the focusing mechanism could actually be aligned across south
Georgia and be displaced southward of the forecast area. Looking
ahead to Thursday, it appears the boundary will drift back northward
and become aligned across the forecast area. As this occurs, the
trough aloft should start to amplify in response to an upper low
developing and shifting southward out of Canada and into the Upper
Midwest and Northern Plains. Precipitable water values are progged
to surge in excess of 2 inches, setting the table for more
widespread thunderstorm coverage and the potential for locally heavy
rainfall. The highest rainfall chances are advertised in the
Thursday period, with 60-80 percent across the forecast area
(highest for southeast Georgia).
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The late week and weekend period continues to look active across
southeast Georgia and southeast South Carolina. The subtle boundary
is expected to remain in the vicinity with ample available moisture.
Rain chances in the 50-60 percent range are in place each afternoon
and evening. There are some indications that as we progress into the
late weekend and early next week the boundary will wash out and we
could return to a more typical scattered diurnal thunderstorm
coverage regime. Temperatures should run a few degrees below normal
for mid to late August.
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
The main challenge with the 0Z TAFs will be the timing and
placement of showers and thunderstorms later this evening. Based
on the latest run of the HRRR, showers and thunderstorm coverage
appears the greatest near KCHS and KJZI between 3-6Z. The TAFs
will highlight the potential for convection with a TEMPO,
featuring a TSRA. In addition, KCHS, KJZI, and KSAV TAFs will
indicate VCSH from late this evening until close to daybreak
Tuesday morning. During the daylight hours Tuesday, winds will
veer through the day, turning from the NW by late afternoon.
Extended Aviation Outlook: Mainly VFR conditions expected. Brief
periods of flight restrictions will be possible in showers and
thunderstorms through the weekend.
Tonight: South to southwest winds will continue overnight ahead
of a weak area of low pressure and associated front moving into
the area. Speeds will increase a bit to become a solid 15 knots
with higher gusts, but conditions will stay below small craft
advisory criteria. Seas will mainly be 2-3 feet.
Tuesday through Saturday: South to southwest flow in the 10-15 knot
range will prevail Tuesday before turning lighter and northerly to
northeasterly Wednesday. Through the rest of the week and early in
the weekend winds should no more than 10-15 knots with southerly
flow returning Friday. Overall conditions should remain well below
Small Craft Advisory thresholds.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
647 PM CDT Mon Aug 15 2022
(Tonight through Tuesday night)
Issued at 231 PM CDT Mon Aug 15 2022
Increased organization occurred on the low pressure system that
developed some tropical characteristics after the center made
landfall, and this made for an active pattern over our western half
of the forecast area this afternoon. A sharp contrast between the
cool outflow and outer band allowed for a few tropical circulations
to develop within the stronger cells, but no wind damage reports
have been collected thus far.
Radar loop over the outer banding region has since trended toward a
much reduced threat for rotational cells closer to the Highway 281
corridor. However, a slow intensifying trend appears to be taking
shape over the Rio Grande generally near and to the south of Eagle
Pass where some insolation has destabilized the air closer to the low
pressure center. This could be a brief focus for a tropical funnel
cloud threat through around 00Z, with lowering temperatures likely to
allow for a weakening trend to begin in that region. A local minima
of activity is generally what we expect to see in the hours 00Z
through 05Z based on a good consensus of the Convective Allowing
Models; however, recent runs of the HRRR might signal some
overreaction of a potential flash flood outbreak over the Eagle Pass
area in the early evening. We think this might be a slight
overreaction of the afternoon HRRR runs and will stick with the
previous runs for that activity minima. It is only mentioned here to
acknowledge that not all models show the same signals. What is more
in harmony is the model depictions of a redeveloping trend of feeder
cells in the overnight and early morning hours over Val Verde County,
especially the western portions. While it`s somewhat unusual for
offices to issue a Flood Watch for one county, Val Verde is a large
county and the impacts of a 2 to 6 inch rain will have greater
impacts than over an area where canyons and dry washes in a very
rural environment could make for a lot of low water crossing that
could be quite dangerous. This is also a region where tropical
features sometimes interact with the local terrain and nocturnal
onshore winds to overachieve in their ability to generate a deep
swath of early morning training of heavy rain cells. The parent low
should continue to pull northwest, and we think this threat should
abate in the late morning hours.
Rain chances in the late morning may still be elevated through the
afternoon over the watch area and parts of the Rio Grande plains;
however, there is no support from the Convective Allowing Models to
carry the threat that far out in time. A few showers and storms could
perk up from residual moisture pooling in the late morning Wednesday
along the Rio Grande, but for the most part, high pressure will
Meanwhile the parched areas of Central Texas will continue to see
above normal levels of heat and humidity, leaving a stark contrast
for the high temperature for Tuesday between western and eastern
counties. Humidities will remain elevated for all areas, keeping the
nighttime temps warm and muggy.
(Wednesday through Monday)
Issued at 231 PM CDT Mon Aug 15 2022
Wednesday is a transition day on temperatures out west due to all the
rain that has fallen. Central TX continues to see near triple digit
heat and elevated heat indices of 102 to 107 degrees. The pattern
will change yet again Thursday, as increased troughing over the
eastern CONUS brings unstable northerly flow aloft and pooled mid
level moisture south into Central TX. Thursday max temps are trending
cooler over northern counties to signal some possible cool storm
outflows pushing into the Hill Country and Central TX early in the
day. The pattern of instability, wind, and moisture will be more
similar to the pattern seen last week where storms take on more of a
hit-and-miss nature. Hopefully Central TX counties do miss on this
pattern which should begin to wane Friday evening.
By the weekend, broad ridging develops over TX, but models keep above
normal levels of moisture over the area and thus a small chance for
isolated air-mass storms going into early next week. This might not
be unreasonable, but seeing how the previous cycle of pattern have
operated in this very dry summer, the more probable scenario is that
these rain chances decrease as we get closer in time to those days.
Issued at 647 PM CDT Mon Aug 15 2022
MVFR to possibly IFR conditions will prevail at KDRT through at least
the first half of the TAF period, with a period of MVFR cigs expected
at the remaining terminals during the early morning hours on Tuesday.
Showers with embedded thunderstorms will continue through the evening
at KDRT as a low originating from the Gulf continues to move further
inland. Precipitation coverage is expected to diminish later
tonight, though the cloud cover will linger with ceilings
potentially dropping below 1 kft AGL. The nearby moisture will aid
MVFR cig development at the remaining terminals during the early
morning hours, with the greatest confidence at KSAT and KSSF. For
the most part, light southeasterly winds are expected through the
period. The exception is KDRT where frequent gusts to 20-25 kts are
expected, especially with any thunderstorms.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 76 101 77 101 / 0 0 0 0
Austin Bergstrom Intl Airport 74 99 75 101 / 0 10 0 0
New Braunfels Muni Airport 74 98 75 101 / 0 10 0 10
Burnet Muni Airport 74 98 74 100 / 0 0 0 0
Del Rio Intl Airport 75 91 76 94 / 70 40 10 20
Georgetown Muni Airport 75 100 76 102 / 0 0 0 0
Hondo Muni Airport 74 96 75 97 / 10 10 0 0
San Marcos Muni Airport 74 99 73 101 / 0 10 0 0
La Grange - Fayette Regional 75 100 75 102 / 0 10 0 0
San Antonio Intl Airport 75 96 76 97 / 10 10 0 10
Stinson Muni Airport 76 97 76 98 / 10 10 0 10
Flood Watch through Tuesday morning for Val Verde.
Area Forecast Discussion
National Weather Service Goodland KS
523 PM MDT Mon Aug 15 2022
Issued at 458 PM MDT Mon Aug 15 2022
With the potential for strong, slow moving storms across
northeast Colorado into this evening, have issued a Flood Watch
for potential for flash flooding through 09z Tuesday. Storms over
the Denver metro area have already produced flooding with 1-3"
rainfall amounts. Flash Flood 1hr/3hr guidance is showing 1 to 2
inches of rain to cause potential flooding in localized areas.
.SHORT TERM...(This evening through Thursday)
Issued at 215 PM MDT Mon Aug 15 2022
Concerns remain the same as previous forecast, namely, low end
risk for landspout/thunderstorm development this afternoon across
southern portion of the forecast area along old outflow boundary
from last night, and second a risk for locally heavy rainfall
tonight north of Interstate 70/west of Highway 25. Visible
satellite imagery this afternoon is showing little development
along the outflow boundary, with all of the cumulus south of it
where intense surface heating is occurring. SPC non-supercell
parameter not picking up anything either. Nonetheless, pattern
suggests a non-zero risk given the boundary, but confidence in
development there is low. Meanwhile further north, cumulus
developing across northeast Colorado and western Nebraska may be
more indicative of things to come. MLCAPE has increased to around
1500 j/kg in a very moist airmass with dew points in the lower
60s. Latest run of the HRRR suggesting convection will develop in
southwest Nebraska later this afternoon and early evening, then
merge with large cluster of storms coming out of northeast
Colorado associated with the synoptic scale forcing. May see a few
severe storms early in the evening, with wind being the primary
hazard, and perhaps an isolated hail threat with stronger
updrafts, though deep layer shear is on the lower end and will
limit the potential for hail. Storm intensity will begin to wane
towards 06z with loss of heating, but showers/isolated storms
will linger well into the overnight. Low temperatures will be in
For Tuesday, scattered showers/isolated storms will continue into
the morning hours, with a general southward trend through the
afternoon. Clouds will be slow to erode, especially in eastern
areas, and have lowered temperatures across the board, with highs
mainly in the 70s. The next round of storms for Tuesday afternoon
and evening will develop south of the Palmer Divide and along the
Front Range in southern Colorado, moving east into the adjacent
plains mainly south of the area Tuesday night. Cannot rule out a
stray shower or storm further north, but chances will be low.
Temperatures Tuesday night will fall into the low to mid 50s.
For Wednesday and Thursday, upper flow will be very weak out of
the northwest as ridge amplifies over the western CONUS and a
trough develops near the Great Lakes. Temperatures will slowly
rebound, with highs on Wednesday in the lower 80s and highs on
Thursday in the upper 80s to around 90. Precipitation chances
will be relatively low given the lack of upper forcing, although
there is another weak cold front/wind shift Thursday night which
may serve as a focus for isolated shower/thunderstorm development.
Low temperatures will be in the 50s both days.
.LONG TERM...(Friday through Monday)
Issued at 1249 PM MDT Mon Aug 15 2022
At the start of the long term, we`re situated between two upper-
level lows - one to our north-northeast and another over the western
CONUS. Early in the period a surface low sweeps a boundary across
the area with surface winds shifting northerly. Afternoon highs will
be near normal on Friday, in the 80s. We remain under northwesterly
flow aloft, gradually becoming more westerly into the weekend as
the trough progresses eastward and upper-level ridging builds in.
Embedded disturbances keep chances for showers and storms with
PWAT values increasing above an inch Saturday afternoon onward.
Slightly below normal high temperatures Saturday through Monday,
in the upper-70s to mid-80s. Overnight lows will be in the mid-50s
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 523 PM MDT Mon Aug 15 2022
With the region lying near a couple frontal boundaries, there
will be the potential for mixed flying conditions through much of
the forecast period. Currently VFR will prevail then shift to a
MVFR/IFR mix as ceilings lower, especially from 06z Tuesday
onward. BKN-OVC007-020 expected. VCTS/-TSRA possible after
04-05z. Locally heavy rainfall is possible that may help to
Winds for KGLD, north-northeast around 10-20kts w/ gusts
approaching 30kts after 04z Tuesday. Winds for KMCK, north-
northeast 10-15kts. Gusts up to 25kts 17z-22z Tuesday.
CO...Flood Watch until 3 AM MDT Tuesday for COZ090>092.
Area Forecast Discussion
National Weather Service Grand Rapids MI
736 PM EDT Mon Aug 15 2022
Issued at 736 PM EDT Mon Aug 15 2022
I added showers to Tuesday afternoon`s forecast too. Looking at
tomorrow, both the NAMNEST and HRRR have significantly more
precipitation forecast tomorrow than today over the GRR CWA.
Tomorrow there is not a thermal inversion near 700 mb like there
is today. That results in equilibrium level for convection is
significantly deeper tomorrow than today. I will admit there is
more dry air aloft above 600 mb than today, even so the air is
fairly moist to about 15000 ft so I would think with an upper low
near by, deep northeast winds and some surface heating, we would
see showers again tomorrow, so I put 20 to 30% POP in the forecast
for Tuesday and increased the clouds over some.
UPDATE Issued at 526 PM EDT Mon Aug 15 2022
I have updated the forecast to allow for rain showers over the
I-69 area early this evening. There is just enough instability
for scattered rain showers on the lake breeze convergence
boundary. At 520 pm there is a line showers from north of Lansing
to near Jackson. The showers are shallow since there is an
inversion near 12000 ft capping the convective cells. The showers
may be briefly heavy but total precipitation will likely be less
than a tenth of an inch since the showers will be brier. Once the
sun sets the convection should come to an end.
.DISCUSSION...(This evening through next Monday)
Issued at 256 PM EDT Mon Aug 15 2022
Diurnal showers across the eastern half of Lower Michigan should
be decreasing and ending by this evening.
Quiet weather this week under surface ridging and dry northeast
low level flow. The upper pattern transitions to an Omega block by
the end of the week as an upper low dives south from northern
Canada and becomes vertically stacked to our west with a moist
southerly flow developing. Showers should move in from the west
by Saturday as the deeper moisture and lift arrives and the slow
movement of the low will keep showers lingering through Sunday and
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 736 PM EDT Mon Aug 15 2022
Overall VFR with northeast winds through Tuesday. The evening
showers from today will be gone by 03z for sure, by then skies
should become clear or nearly so.
On Tuesday, it will be similar to today. Day time heating will
cause convection to develop over eastern Lower Michigan by early
afternoon then that will spread west into our CWA by mid
afternoon. The shower may have slightly higher coverage than
today. Even so, showers will be widely scattered so I put VCSH in
most of our TAF forecasts for Tuesday.
Issued at 256 PM EDT Mon Aug 15 2022
Winds and waves will continue to be from the northeast through
Wednesday and the offshore component will keep waves fairly light
along the coast. There could be some choppy 2 to 4 foot waves near
Big and Little Sable Points Tuesday afternoon as winds gust to 20
Area Forecast Discussion
National Weather Service Lincoln IL
831 PM CDT Mon Aug 15 2022
Issued at 309 PM CDT Mon Aug 15 2022
Portions of central Illinois may receive some light rain on
Tuesday morning. Otherwise, near to below normal high
temperatures and cool low temperatures for mid-August are forecast
for this week. Shower and thunderstorm chances return this
Issued at 821 PM CDT Mon Aug 15 2022
A seasonably strong and deep corridor of FGen stretches from
western IA into SW Illinois this hour per latest RAP and this
forcing will remain fairly persistent and mostly stationary
overnight. Meanwhile, 00Z KILX sounding continued to show a deep
layer of dry air below roughly 500 mb (18kft) which is resulting
in erosion of the leading edge of precip and plenty of virga where
returns are noted on radar. Precipitation will continue on the
cold side of the FGen band overnight with gradual top-down
saturation allowing precip to reach the surface eventually, mainly
west of a Galesburg to Effingham line. Precip amounts should
remain light within the central Illinois forecast area, with up to
around a quarter inch possible near portions of the lower
Illinois River Valley.
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 309 PM CDT Mon Aug 15 2022
A surface ridge extending from Ontario southwestward into the
upper Midwest is leading to northeast winds around 10 mph or so
this afternoon. Visible satellite shows an extensive scattered-
broken low cloud field over central Illinois, with higher clouds
moving in from the northwest associated with the next approaching
HRRR forecasts show a developing northwest-southeast band of
strong warm advection at 850 mb from southeast NE into central MO
from late tonight into early Tuesday morning. In addition,
frontogenesis will be occurring along this band as a warm front
strengthens. Associated perhaps with both frontogenetic and
isentropic lift, an area of showers and thunderstorms is
anticipated to develop on Tuesday morning. 12z CAMs have mostly
shown this precipitation to be farther south than previous runs,
with 24 hr HREF LPMM QPF in the 0.1-0.25" range over Morgan and
Scott counties, lower to the northeast. NBM 90th percentile
rainfall amounts in the southwest corner of the ILX CWA remain
around 0.75", so though the probability of a more northward track
has decreased it is still within the realm of possibility.
Forecast soundings show minimal instability with thunder
probabilities low (~5%).
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 309 PM CDT Mon Aug 15 2022
The main forecast concern for the Tuesday night through Monday
period centers around rain and thunderstorm chances for Friday
through the weekend.
Late in the week, ensemble member forecasts show a strong ridge
persisting over the Pacific Northwest with a closed low developing
within northerly flow somewhere over the upper Midwest. Ensemble
clustering reveals some spread regarding the depth of this low,
with about 80% of solutions on the shallower side and about 20% on
the deeper side. Should a solution falling in the deeper cluster
verify, instability may be a bit lower as drier air works in.
Either way, shower and thunderstorm chances are anticipated to
return to some degree from Friday into the weekend with 30-40%
PoPs primarily in the afternoon/evening. Heavy rainfall and severe
probabilities appear low at this time.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 624 PM CDT Mon Aug 15 2022
A warm front will be in place from NW to SE Missouri this evening
and overnight and will serve as the focus for thunderstorms. While
some light showers may reach as far east as SPI, dry air and lack
of instability will keep impacts from precip minimal and no
thunder is expected this far east. NE winds will prevail most of
the period but may become light and variable at times overnight.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
750 PM PDT Mon Aug 15 2022
...Significant Heat Far Inland Areas for Tomorrow...
.SYNOPSIS...Gradual warming and drying continues as high pressure
builds into the area from the east. Excessive heat concerns for the
more interior locations expected tomorrow. Cooler conditions
expected into next weekend.
.DISCUSSION...as of 02:30 PM PDT Monday...Temperatures across the
area are currently in the 60s near the water with a compressed
marine layer holding tight near the coast. Temperatures increase
quickly further inland, with temps in the upper 80s and then 90s
further inland. Temperatures will continue to rise through the
afternoon with highs today reaching mid 90s for interior valleys
and upper 90s further inland. Our usual hot spots in the interior
East Bay could see temps reach low triple digits this afternoon.
Hazy conditions and small concentrations of smoke from the Six
Rivers Lightning Complex fire to advect southward into the Bay
Area possible, as indicated per the High Resolution Rapid Refresh
smoke model. Small concentrations of near surface smoke could
create hazy conditions and impact air quality. This risk will be
more concentrated towards the North Bay.
Temperatures are still on track to be the warmest tomorrow
afternoon. As such, the Heat Advisory is in effect from 11 AM to
8 PM Tuesday. An update from the previous discussion is that the
southern portion of the Salinas Valley and interior Monterey
County (including the Santa Lucia Mountains) were included in the
Heat Advisory. Temperatures in the interior will likely reach
triple digits with some areas in the farther interior near the Sac
Valley reaching or exceeding 105 degF. The area most likely to
see temps reach 105 are the interior portions of Contra Costa and
Alameda counties as well as southern Monterey and San Benito
This results in a moderate HeatRisk for much of our area, with a
high HeatRisk for locations bordering the Central Valley, including
eastern portions of Contra Costa, Alameda, Santa Clara, and San
Benito Counties. Higher elevations in the Santa Lucia mountain
range are also highlighted as a high HeatRisk. This means there
is a risk for heat- related illnesses to those who are sensitive
to heat (in the moderate risk area), with this risk extending to
most of the population in the high risk area. This concern is
greatest for those without effective cooling and/or adequate
hydration so be sure to check on your friends, neighbors, and
outside workers during this heat event. Please use caution as
temperatures will be dangerously hot in areas that are under High
HeatRisk (such as interior East Bay). If planning to partake in
outdoor activities, hydrate and take breaks often. If possible,
seek AC and cooler conditions if further inland. For more specific
information regarding where you are in terms of HeatRisk, check
out wrh.noaa.gov/wrh/heatrisk/ or weather.gov/heat.
Looking beyond Tuesday, temperatures will continue to be toasty
but start to gradually decrease. Subsequently, the HeatRisk on
Wednesday has less aerial coverage in the "High" HeatRisk
category, but a majority of our cwa remains under the "Moderate"
risk. For now, the Heat Advisory is only in effect during the day
and evening tomorrow, but stay tuned for upcoming forecasts to
see if the Heat Advisory will be extended. However at this time,
the Heat Advisory is only in effect for Tuesday. In addition,
conditions will be hazy in the Bay Area and North Bay as small
concentrations of smoke meander southward.
A surge of monsoonal moisture in the midlevels of the atmosphere is
expected to arrive tonight as well. There is some slight
instability associated with this surge of moisture (100 to 200
J/kg of MUCAPE) but at this time stays confined to over the
waters and near the coast. A slight chance for rain (15% PoPs)
was added to the forecast over the waters Wednesday overnight.
Confidence remains low on thunder chances Wednesday night, so not
included in the forecast. We will continue to monitor for this
Into the longer term, heat concerns begin to diminish by
Thursday and temperatures cool off to more seasonable
temperatures by the weekend.
.AVIATION...As of 7:50 PM Monday... For the 00Z TAFs. The marine
layer depth varies from 300 feet at Bodega Bay to 1,100 feet at
Fort Ord per recent profiler data. It`s VFR across the cwa except
for coastal stratus and fog /VLIFR-IFR/ which is patchy along San
Mateo County to a more continuous coverage from southern Santa Cruz
County southward along coastal Monterey County. The ACV-SFO pressure
gradient has strengthened to 7.8 mb. Downsloping and drier northerly
winds along with a compressed marine layer is resulting in a full
erosion of stratus and fog along the coastal North Bay. HREF output
shows a slow recovery in coastal stratus and fog /VLIFR-IFR/ tonight
and Tuesday morning. Since the ACV-SFO pressure gradient and wind
outweighs the onshore (2.3 mb) SFO-SAC pressure gradient and wind
and the marine layer is forecast to stay compressed, expect very
little if any stratus and fog intrusion into the Bay Area tonight
and Tuesday morning.
Wildfire smoke from the Six Rivers Lightning Complex over far
northern California continues to arrive in our cwa on northwest
winds. The HRRR vertically integrated smoke forecasts continue to
show smoke arriving through most of Tuesday, then by late Tuesday
and Wednesday winds shift to a southerly direction which should
help disperse smoke layers.
Vicinity of KSFO...VFR, west wind 15 to 25 knots decreasing to less
than 10 knots late tonight and Tuesday morning. West wind returning
and gusty to 20 knots Tuesday afternoon and evening.
KSFO Bridge Approach...Similar to SFO.
Monterey Bay...Stratus and fog /VLIFR-IFR/ tonight and Tuesday
morning. Conditions lifting to VFR by late Tuesday morning and
afternoon. Onshore winds 10 to 15 knots to mid to late evening,
decreasing to around 5 knots overnight and Tuesday morning. Winds
increasing to 10 to 15 knots Tuesday afternoon and evening.
.MARINE...as of 01:42 PM PDT Monday...Strong northwesterly winds
continuing across the coastal waters, with near-gale-force gusts
possible in the northern outer waters. Steep, hazardous short
period seas will build as a result. Winds diminish Tuesday
afternoon through mid week. Light southwest swell from 14 to 16
seconds continues through the week.
.Tngt...SCA...SF Bay until 9 PM
SCA...Mry Bay until 9 PM
SCA...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM
SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM
PUBLIC FORECAST: McCorkle/SPM
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
930 PM EDT Mon Aug 15 2022
Low pressure will track southeast across the Carolinas through early
Tuesday, then offshore later Tuesday and Tuesday night.
.NEAR TERM /THROUGH TONIGHT/...
As of 930 PM Monday...
Surface low pressure has situated itself over upstate SC as of 00z
surface analysis creating predominately northeasterly low-level flow
over central NC. Regional radar imagery shows all of the deeper
convection over the NC/SC border while some lighter more isolated
showers have developed over the Sandhills and Coastal Plain. Some
isolated/scattered showers will remain possible through tonight as
the H8 low, currently located over western NC based on recent RAP
analysis, will slowly shift east-southeast tonight providing
isentropic lift and WAA over a majority of central NC. Recent CAM
guidance shows this solution as light showers begin to blossom over
the area, however, overall coverage is still in question with the
NAM showing the most widespread showers. In addition, this regime
will promote low overcast across the area tonight which should
linger through a majority of the day Tuesday. Lows, inherently, will
be moderated by the cloud cover and only drop into the mid/upper 60s.
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 340 PM Monday...
A mid-level cyclone developing over the nrn Mid-Atlantic today will
remain in place through 12Z Wed, with associated low amplitude/
weakly-perturbed wly to wnwly flow directed across cntl NC.
In the low levels and at the surface, an 850 mb low will track
slowly east and across s-cntl and sern NC with a related band of
frontogenesis through Tue evening, then offshore. The flow around
that cyclone will also promote WAA/isentropic upglide across a wavy
surface frontal zone that will sag sewd across the coastal Carolinas
and atop high pressure that will ridge swwd across the Mid-Atlantic
and interior Carolinas.
Moist nely low level flow, and a thick saturated/overcast layer up
through 700 mb, will result in cloudy conditions through the
forecast period, along with mixed character light/rain showers that
will focus along and north of the 850 mb low (ie. directly across
cntl and ern NC) through Tue afternoon-evening. While additional
rainfall amounts are expected to be light, generally a tenth to a
third of an inch, the clouds and occasional rain will result in warm
season CAD and minimal diurnal range in temperatures: well below
normal (10-15 F) high temperatures in the 70s and lows in the 60s.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 210 PM Monday...
An upper low over will sit over the Northeast Wed/Wed night, with
the longwave trough extending south-southwest toward the Gulf Coast.
The aforementioned low will lift to the north on Thu/Thu night as
another northern stream low dives south from central Canada into the
northern Plains/Western Great Lakes, where it will sit through
Friday before gradually migrating eastward into the OH Valley over
the weekend. The upper trough axis may fluctuate in its
amplification Thu/Fri, before becoming anchored with the low over
northern Plains/Western Great Lakes. By Monday, the low should be
over the central/eastern Great Lakes, while the trough axis extends
south-southwest, roughly along the Appalachians.
At the surface, while a deepening low will drift northeast off the
East Coast Wed/Thu, an area of low pressure will linger off the NC
coast, while relatively high pressure dominates over central NC.
Beyond Thu the surface pattern becomes a bit more variable and
uncertain, but an inverted trough or relative area of low pressure
is expected either along the Southeast/Carolina coast or inland over
the Southeast and Carolinas.
The driest days should be Wed/Thu while the low lingers over the
Northeast, with increasing chances for showers/storms with the
trough to the west. As for temperatures, highs could remain below
normal through the weekend, while lows may creep up from below
normal to just above normal.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 800 PM Monday...
Numerous showers and storms continue to move along the NC/SC border
and are expected to drift southeast, but some isolated storms may
still impact FAY over the next couple hours. Otherwise widespread
MVFR/IFR ceilings are expected to develop along with some showers
possible at all TAF sites within the northeasterly low level surface
flow. Conditions will be slow to improve to MVFR Tuesday morning
with locations across the south, including FAY, having the potential
to remain IFR through the remainder of the TAF period. Locations
across southwest VA into northwest NC have a chance to fall to LIFR
early Tuesday morning, but confidence was too low to introduce it at
this time. -Swiggett
Looking beyond 00z Wednesday, rain chances will decrease by Tue
night-Wednesday, with mainly diurnal showers and a few thunderstorms
as the front stalls south and east of the area. The continued moist
NELY low-level flow associated with a weak warm season CAD event
will result in high chances of sub-VFR ceilings Tuesday night and
Wednesday night, that could be very slow to lift throughout the day,
particularly at KINT and KGSO. Rain chances could increase late in
the week as some upper disturbances move through the southern Mid-
Area Forecast Discussion
National Weather Service Blacksburg VA
734 PM EDT Mon Aug 15 2022
Low pressure aloft will build toward the Mid-Atlantic through
the week. This will result in a very unsettled weather pattern
across the Mid- Atlantic and Appalachians. Rain and a few
thunderstorms can be expected nearly every day. Temperatures
will remain below normal all week.
.NEAR TERM /THROUGH TUESDAY/...
As of 725 PM EDT Monday...
Convection has diminished somewhat early this evening but still
area of deep moisture flux convergence exists along wedge
boundary from southeast WV into the NC Blue Ridge. With the
upper low over the northern Mid-Atlantic, will likely see a few
more vorts rotate across into the mountains overnight with
showers scattered about. However with surface instability
dwindling, showers should not be as excessive, so will let the
flood watch expire at 8pm.
Overnight looks to be cloudy and drizzly in the wedged areas
similar to our cool season set up, with a few showers here and
there. Fog will likely be patchy but seen area wide. Higher
elevations could be stuck in dense fog so will monitor this.
Currently, weak surface low is centered over eastern Kentucky/far
southwest Virginia with a stationary front roughly located from far
southern West Virginia stretching across southern Virginia. This
boundary is mainly evident by visible satellite where a thick
stratus cloud deck is in place. Areas south of the stationary front
have seen some breaks in cloud cover and have in turn warmed into
the 70s, thus seeing RAP analyzed SBCAPE values of 1000-2000 J/kg as
destabilization continues. Have already seen a few heavier rain
clusters and embedded storms form within the last hour in the warm
sector over northwest North Carolina. These newly formed clusters
are within a zone where 25-45 kt effective bulk shear, marginally
lapse rates and modest MLCAPE overlap. This area should (i.e.
southwest Virginia into North Carolina) continue to promote at least
a few storm clusters through the afternoon/evening, capable of
producing strong winds, heavy rainfall, and some localized instances
of hail. It is also worth mentioning that while still very low, the
tornado threat is not zero, especially since we are dealing with a
Severe threat likely to subside by this evening with maybe some
lingering thunderstorms in the far southern portions of the CWA.
Rain showers and drizzle will continue overnight and fairly
widespread fog settles in as the wedge strengthens and builds south.
Cool air wedge likely to remain solidly in place for Tuesday, thus
the cloudy, cool, and rainy conditions will continue. Went a bit
lower on guidance for tomorrow for high temperatures with upper 60s
to low 70s the general theme. With less instability, thinking
thunderstorm threat will remain much lower so only kept mention of
storms along and south of the VA/NC for an isolated chance.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 110 PM EDT Monday...
Cooler than normal temperatures expected...
The short term portion of the forecast will be dominated by a
surface wedge of high pressure. Aloft, an anomalously deep upper
level trof (1-2 standard deviations stronger than normal will reside
over the northeast U.S. on Wednesday before lifting on Thursday.
While there is high confidence that temperatures will be below
normal, there is considerable spread in the NBM regarding the
temperature values Wednesday and Thursday, leading to lower than
average confidence. Went a couple of degrees lower than the NBM
guidance considering the magnitude of the upper level trof and
associated sfc wedge, but the amount of cloud cover will be key in
On Wednesday, an impressive 100+ kt upper level jet max sweeps over
our region and the southern portion of our forecast area will reside
under the RR quad of this jet coincident with increasing upper level
divergence. Despite the deeper moisture remaining well south of our
area, forecast soundings showing saturation below 10K ft combined
with this forcing should generate scattered showers, especially
across the NC mountains.
As the upper level trof and jet max lift, chances for precipitation
diminish on Thursday. The exception may be across the east facing
slopes of the Blue Ridge, and especially the southern Blue Ridge,
where a weak upslope flow and lingering moisture below 600mb will
continue to spawn scattered showers/areas of rain.
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 1215 PM EDT Monday...
Chances for showers and storms increases for the weekend into
early next week...
The long range deterministic models are in general agreement that a
the long term period begins with a broad upper level trof covering
the eastern U.S. with an upper level low digging south into the
Upper Mississippi Valley, with the trof axis shifting east by
The WPC cluster analysis output shows decreasing confidence with
time with regard to the magnitude and timing of this trof late in
the weekend into Monday, with the ensemble mean suggesting the trof
weakens similar to the 00Z/15 GFS or Canadian runs.
As this upper trof approaches the low level wedge in place weakens
with the GEFS 31-member ensemble output showing the probabilities of
CAPES exceeding 1000 j/kg increasing each day from Saturday through
Monday. With PWAT values also increasing, increased POPS
Temperatures will moderate as the NCEP Ensemble mean shows a fairly
strong signal of below normal 850mb temps on Friday, gradually
warming to above normal by the weekend. The potential for mostly
cloudy to cloudy skies, however, will likely keep temps near normal
late in the period.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 730 PM EDT Monday...
Poor flying conditions expected for most of the taf period, as
wedge and scattered showers hold in low level moisture. Shower
chances higher in the LWB/BLF/BCB areas this evening and perhaps
ROA but overnight expect showers to be widely scattered, with
drizzle anticipated in the wedged areas at times, along with
cigs below 1kft and vsbys in the 1-4sm range, sinking to less
than 1sm higher elevations, so BLF could see this.
Should see low cigs/vsbys improve slowly Tuesday though may
have sub-VFR into early afternoon across the ROA-LYH corridor.
More shower scattered about in the afternoon but not enough to
mention in the tafs.
.Extended Aviation Discussion...
As the upper low retrogrades to the west through the week,
precipitation will tend to become more convective in nature.
This will result in increased periods of VFR during the daytime
into the evening with overnight potential for dense fog at
LWB/BCB and other areas that may have rain. Bottom line is that
the entire week will remain unsettled with shower and
thunderstorm chances all week.
VA...Flood Watch until 8 PM EDT this evening for VAZ007-010-011-018-
WV...Flood Watch until 8 PM EDT this evening for WVZ042>044-507-508.
Area Forecast Discussion
National Weather Service Topeka KS
937 PM CDT Mon Aug 15 2022
Issued at 937 PM CDT Mon Aug 15 2022
Showers and thunderstorms have developed across southern NEB a few
hours sooner than the models have and it looks like the HRRR is
still trying to catch up with reality. So have increased POPs and
bring precip into the northern parts of the forecast area over
the next hour or two. Models show surface based instability
continuing to diminish as the boundary layer cools, and forecast
soundings from the RAP suggest only a few hundred J/kg of elevated
instability across the northern counties. Effective shear
analysis from SPC shows 40KT to 50KT are still available so there
may be an isolated intense updraft that could produce some
damaging winds. Freezing levels around 14KFT imply the updraft
would have to be really intense with 50dBz levels approaching
40KFT for hail. So with the marginal instability, large hail
appears to be a low probability.
Issued at 254 PM CDT Mon Aug 15 2022
- Cold front moves through tonight, chance of showers/storms into
- Much cooler weather arrives for tomorrow, sticks around through
A current look at surface observations across the area shows the key
players in our much awaited transition to cooler weather. A nearly
stationary front is in place across eastern Kansas, stretching
eastward from a 1009 mb low over the southern Kansas/Colorado
border. High pressure to the north is keeping easterly flow in place
to the north of the boundary, with widespread clouds and
precipitation developing just across the state line into Nebraska.
So there is quite a contrast in temperatures on either side of the
front. Temperatures near the Nebraska border are in the upper 70s
and low 80s, while along and south of I-70 temperatures have climbed
into the 90s and even low 100s amidst southerly winds and strong
This afternoon and evening, will still need to watch out for an
isolated storm or two developing along the front this afternoon and
evening, along a line from Concordia to Burlington. Shear 30-40 kts
and 2000-3000 J/kg of MUCAPE could support a strong to severe storms
if any develop. However despite a lack of significant CIN, it
remains more likely that nothing develops in this area as the better
upper support from the main shortwave will remain to the north. The
better chance for showers and a few thunderstorms will occur late
this evening and tomorrow morning as the surface low to the west
shifts southeast, dragging the cold front south through the
remainder of the area. The axis of heaviest precipitation does look
likely to stay north and east of the area, given the track of the
stronger mid-level vorticity to the north. So total rainfall should
be highest in far northeast Kansas, at perhaps around a half inch,
decreasing with southwestward extent. Clouds and occasional showers
will stick around for much of the day tomorrow, keeping temperatures
well below average. Highs should stay in the 70s for most, perhaps
even 60s in a few spots if thick cloud cover can stick around
through the afternoon.
Wednesday through the weekend, the cooler than average weather
sticks around. An additional upper low drops south into the main
longwave trough late week, reinforcing the mean trough and keeping
the overall pattern in place. So highs should generally stay in the
80s with lows in the low/mid 60s, with just some minor variations
depending on the timing of individual shortwaves. High pressure
initially keeps things dry Wednesday and Thursday, with rain chances
increasing Friday into Saturday as the upper low moves in.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday)
Issued at 547 PM CDT Mon Aug 15 2022
Models show the main synoptic scale forcing for showers and storms
moving across northeast KS after 06Z. Think the convection near
KCNK is more diurnally driven. So it may still be some time
before precip impacts the terminals. The models are in agreement
that at least MVFR CIGS will move in behind the front and could
last through much if not all day Tuesday. There could even be a
period of IFR CIGS as the front passes. For now will use the model
consensus for timing the lower clouds and the CAMs for a VCSH at
the terminals. Coverage of storms from the CAMs appears to remain
scattered enough to limit confidence in a prevailing SHRA. And
instability looks to be fairly limited for widespread TS.