Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/09/23
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
947 PM CDT Sat Apr 8 2023
.UPDATE...
Issued at 944 PM CDT Sat Apr 8 2023
Satellite picture this evening features streams of mid-level
clouds and stratus through the Turtle Mountains. Some fog still
looks possible tonight, with high-res models showing just patchy
to areas of fog in coverage after 05Z. No changes needed with
this update.
UPDATE Issued at 623 PM CDT Sat Apr 8 2023
Forecast issue tonight continues to be stratus and fog. Modestly
high dew points this evening should allow for some fog to develop
as winds become light overnight, especially to the central and
east ahead of the pressure trough. Can`t rule out stratus
returning as well, though confidence hasn`t really increased from
the previous shift. With this update the sky forecast was bumped
up a bit as mesoscale models do continue to hint at fog or cloud
cover expansion, but further details will need to wait until
observational trends develop.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 150 PM CDT Sat Apr 8 2023
The main forecast issue in the short term period will be
fog/stratus and temperatures.
Latest surface analysis shows a warm front from northeast Montana
into northwest Montana. Surface high pressure was over the Great
Lakes with low pressure in the lee of the Northern and Canadian
Rockies. Latest satellite imagery showed high clouds propagating
from central into eastern North Dakota, with thinner cirrus/ more
sunshine across the west. A pesky area of stratus over the
southwest looks to be diminishing as it lifts northeast.
For late this afternoon through tonight. The far southwest should
warm into the lower 60s this afternoon, but most of the area,
especially north and east of the Missouri River will remain in the
30s. Tonight, uncertainty remains in the potential for low
stratus/fog. Mesoscale models show the stratus over the southwest
lifting north northeast and RAP shows possible stratus/fog moving
into Minot this evening, with more widespread stratus/fog over
eastern ND. Not certain at all with this and have leaned more
towards a partly cloudy sky. With that said, the pressure
gradient does relax tonight and with mainly thin high clouds this
evening, can not rule out some patchy fog. Previous shift had
added some patchy fog and see no reason to pull it at this time.
Sunday looks like another warm day in the far southwest and
westtratuscentral, with cooler temperatures as you go north and
east (but warmer than today). Like today, expect that there will
be a sharp transition zone between the warmer temperatures with
bare ground and colder temperatures under the deep snowpack. As we
go forward into the extended period think this sharp gradient in
the transition zone will slowly weaken as we lose our snowpack.
But with the melting snowpack comes the threat of flooding of low-
lying areas. See the current Hydrologic Outlook (ESF) for further
details. This transition zone could also be a focus for fog
stratus issues as well.
.LONG TERM...(Sunday Night through Saturday)
Issued at 150 PM CDT Sat Apr 8 2023
The main forecast issue in the long term period will be temperatures
through mid week, then precipitation chances later in the week.
For what seems to be ages, we have a spell of unseasonably warm
temperatures to deal with early next week. Except for portions of
the far west central and southwest, snowpack remains substantial.
Looking at the trend of the NBM 4.1 ensemble temperatures Sunday
through Tuesday, the ensemble spread has increased the last couple
of days, especially over central ND, including Bismarck and Minot,
while spreads in the west are much more reasonable, even a bit too
tight. For instance on Monday and Tuesday the ensemble spread at
Dickinson is 6 and 5 degrees, respectively. At Bismarck the spread
is 23 and 29 degrees, for the same days. As you go east, the spread
is also high, but is delayed a day or so. Perhaps there may be a
target of opportunity in the west, or spreading into the central
later in the period, but as long as the snowpack remains and
ensemble spreads are wide, will stick with our given guidance. In
addition to the temperatures, we see building upper level ridging
through mid week. At the surface, the pressure gradient does not
seem overly tight throughout the period. There are periods when it
tightens a bit but also periods when you see it relax. Therefore, we
would not be surprised to see occasions with stratus/fog issues,
especially near the boundary between bare soils and the
snowpack.
Beyond Wednesday, we transition to more of a southwest upper flow
and will see periodic chances of rain/snow as we head through the
latter portions of the work week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 623 PM CDT Sat Apr 8 2023
Return of IFR stratus or some fog is possible tonight, but
certainty is low for any one location. It does seem the south
central to southeast, KBIS-KJMS, looks to have a bit of a higher
potential for some sort of impact. So the TAFs were kept VFR with
this forecast due to uncertainty, but included SCT IFR cigs at
both sites with VCFG. Winds generally become westerly during the
day Sunday after becoming light tonight.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...AE
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...AE
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
604 PM CDT Sat Apr 8 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Sunday night)
Issued at 249 PM CDT Sat Apr 8 2023
Plenty of clouds remain intact across most of south central Texas
early this afternoon. We are seeing some breaks in the clouds across
portions of the Hill Country and I-35 corridor near San Antonio.
These areas will see a little extra heating and some re-development
of low clouds as the afternoon progresses.
For tonight, cool and moist air in the boundary layer will persist,
allowing for widespread low cloudiness, patchy fog and overnight
lows in the lower 50s to near 60. Some of the hi-res models show
some weak shower activity is possible out west across the Rio Grande
plains as southeasterly flow in the low-levels begins to strengthen.
Confidence in this is low, so we will not mention in the forecast at
this time.
Mostly cloudy skies along with afternoon highs in the upper 60s to
upper 70s are expected on Sunday. We will see some weak disturbances
embedded in the west-northwest flow aloft move into the region
beginning late Sunday afternoon and continuing through Sunday night.
We will keep a low chance for showers and thunderstorms limited to
northwestern Val Verde county during the mid to late afternoon
hours, then slowly spread rain chances farther east into the Rio
Grande plains during the evening Hill Country, with the Hill Country
seeing some activity during the overnight hours. Coverage will
likely not be much more than isolated to widely scattered, so we
will keep rain chances limited to 20% for now.
&&
.LONG TERM...
(Monday through Saturday)
Issued at 249 PM CDT Sat Apr 8 2023
A shortwave trough advances across the state on Monday before
evolving into a cutoff upper level low near the northwestern to
northern Gulf Coast into midweek. The shortwave will help to
initiate a region of convection across the Texas panhandle late
Sunday. The north-northwesterly flow behind this shortwave should
help to propel the convection southward toward our region into
Monday. The main question that remains, however, is if this
convection is able to hold together during the overnight on that
journey? The global models, especially the GFS, are optimistic
whereas the hi-res guidance coming into range (NAM12, the HRRR
through 12Z Monday) are less optimistic on the activity holding
together and approaching from the north. Will keep the chance of
rain/storms in the forecast but will lower PoPs from the NBM
guidance. Tuesday may also potentially offer a slight chance for
rain across our eastern zones but this will all depend on the
proximity of where the low pressure system wraps up. The farther
east it wraps up, the drier the forecast would be. Expect for
afternoon highs in the 70s and overnight lows in the 50s through
midweek with the northerly flow on the western side of the low.
Afternoon temperatures return to the 80s and dew points will be
climbing back into the 60s by late this week as the winds become
southeasterly with the gulf system moving away to the east-
northeast. In addition, a shortwave ridge builds over the state
during Thursday into Friday ahead of a trough moving through the
Desert Southwest. The approaching trough may be a catalyst for
returning rain/storm chances from Friday night through Saturday,
including perhaps the chance for some organized convection as
instability builds and shear increases with a stronger southwest
flow aloft.
&&
.AVIATION...
(00Z TAFS)
Issued at 546 PM CDT Sat Apr 8 2023
The San Antonio airports are enjoying VFR conditions as clouds spread
and continue to lift late this afternoon. However, for KAUS, overcast
skies around 1 to 2 Kft are expected to remain through the overnight
hours. For KDRT, mostly sunny skies are in place and expected to
stay for the next few hours with partly cloudy skies this evening.
Increased moisture arrives this evening for the San Antonio terminals
with MVFR cigs forecast for the tonight into Sunday morning period.
There is a chance for IFR cigs to affect the San Antonio and KDRT airports
around 10 to 12z and last for several hours. VFR conditions are
forecast to show around 20z. Light northeast winds are forecast
for area airports for most of the forecast period with a moderate southeast
wind flow for KDRT.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 57 75 58 74 / 0 0 10 30
Austin Bergstrom Intl Airport 55 73 57 73 / 0 0 10 30
New Braunfels Muni Airport 55 75 58 74 / 0 0 10 30
Burnet Muni Airport 54 73 55 72 / 0 0 10 30
Del Rio Intl Airport 61 79 63 80 / 0 10 20 40
Georgetown Muni Airport 55 72 55 72 / 0 0 10 30
Hondo Muni Airport 55 75 58 76 / 0 10 10 40
San Marcos Muni Airport 55 74 57 74 / 0 0 10 30
La Grange - Fayette Regional 57 73 58 72 / 0 0 10 30
San Antonio Intl Airport 56 74 59 74 / 0 10 10 40
Stinson Muni Airport 57 75 60 75 / 0 10 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...17
Long-Term...27
Aviation...17
Area Forecast Discussion
National Weather Service San Diego CA
1241 PM PDT Sat Apr 8 2023
.SYNOPSIS...
Fair and mild weather today will turn even warmer tomorrow and
Monday as a ridge builds over the Southwest. Weak onshore flow and a
shallow marine layer could lead to areas of dense fog along the
higher coastal terrain, and even along the coast for the next few
nights. Cooling begins on Tuesday as the ridge drifts to the east,
and is replaced by a trough. This sets up much cooler weather for
the latter half of next week, along with a limited shower threat
Thursday or Friday. The weather looks dry and a bit warmer again by
next weekend.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Satellite imagery at midday showed patchy high clouds drifting SE,
and a large area of low, marine clouds just offshore. Weak onshore
sfc pressure gradients were holding and supporting some westerly
wind gusts over 30 MPH near the passes. Surface dewpoints were in
the 50s F along the coast and over the near-shore islands. As these
are maintained by sea breezes this afternoon, there should be
sufficient moisture for fog development overnight, provided the
skies remain mostly clear. In the meantime, skies will be fair as
temperatures approach the 70 degree mark this afternoon.
A weak trough along the West Coast has kept the weather over SoCal
on the cool side for the past few days, but that is about to change
as a ridge begins to build tonight. By tomorrow, the warming will be
noticeable, especially inland, peaking on Monday under sunny skies.
Weak sea breezes will temper the warming along the coastal strip, to
just a few degrees Fahrenheit in the afternoons, but inland, highs
will be 6-10F above average. A shallow marine layer is likely to
persist as well, raising the prospects of fog. Based on the latest
HREF and HRRR model runs, the best chance for dense fog (60-70%)
will be along the higher coastal terrain tonight, and then closer to
sea-level Sun night/Mon morning. The greatest potential for
widespread, dense fog, appears to be Sunday night/Mon morning, but
some fog is likely each night through Monday night.
The ridge aloft peaks over AZ on Monday, but continues to be the
main feature controlling the weather over SoCal through Tuesday. The
onshore sfc pressure gradient will begin to accelerate then, but
this will mainly be felt west of the mountains in the afternoon. The
lower deserts will remain quite warm. By Wednesday, our weather
pattern flips completely as a trough digs down the West Coast and
the ridge fizzles. This will result in noticeably windy and colder
conditions over over SoCal, that will continue through Thursday.
Track, intensity, and outcome of the energy moving through our next
digging West Coast trough remains elusive, as evidenced by the
spread in outcomes on the last few control runs of the global
models. The problem centers around the energy cutting off a low
pressure center somewhere near SoCal....Tis the season. Therefore,
confidence in our weather for the middle of next week is quite low,
especially for precipitation. For now, we can be quantify it with
the trend in the ensemble output. At this point it still suggests
some light precipitation is likely around the Thursday timeframe,
but exact timing is difficult to gauge. Strong and gusty westerly
winds, and cooling look more certain, peaking on Thursday.
Count on some warming as the system exits to the east next weekend,
but even that looks somewhat muted as the global models try to
adjust to the potential development of a blocking pattern over
the West. Blocks are difficult, especially around the edges where
cut-off lows frequent.
&&
.AVIATION...
081930Z...SCT conditions expected for much of the afternoon, with
BKN-OVC low clouds redeveloping after 00Z Sun. Bases are expected to
start at 1000-1500 ft MSL, with the potential to lower to 600-800 ft
MSL. 12Z ensemble guidance has 70-80% of cigs under 1000 ft after
10Z Sun at coastal TAF sites. Vis reductions of 1-3SM expected near
areas of higher coastal terrain. Cigs and vis restrictions should
clear by 17Z Sun.
&&
.MARINE...
West-northwest wind gusts could briefly reach 20 kt in the outer
coastal waters through early this evening. Areas of fog and reduced
visibility possible over the waters tonight. Low confidence in
widespread dense fog. Better chances of more widespread, potentially
dense fog Sunday night into Monday. For the middle to end of next
week, gusty northwest winds near 25-30 kt expected along with seas
of 9-11 feet.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
PUBLIC...10
AVIATION/MARINE...CO