Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/02/19
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
919 PM CDT Wed May 1 2019
.UPDATE...
Loss of heating has allowed for convection over the higher terrain
of Mexico to wane this evening along the Rio Grande with attention
for rain chances tonight remaining focused across Central Texas into
the Hill Country. Aircraft soundings out of Austin and San Antonio
showed a gradual weakening/lifting capping inversion late this
afternoon, but latest soundings have shown very little overall change
in the cap the past 1-2 hours across the metro areas. Ongoing
convection across Hamilton/Bosque Counties does indicate the cap is
weaker just north of the Austin metro though. Have maintained a
mention of isolated to scattered thunderstorms through the remainder
of the evening across the Central Texas counties as a broad vorticity
maxima evident on SPC Mesoanalysis continues to lift across the
Edwards Plateau.
Farther north, a mesoscale convective system (MCS) draped roughly
along the Interstate 20 corridor has produced a series of outflow
boundaries evident on both the KDYX and KFWS radars. Simple
extrapolation of these boundaries` current movements would place them
into the Hill Country/Central Texas between 3-5 AM (but modification
of their associated cold pools may result in a slower arrival... or
keep these boundaries from reaching the forecast area entirely). Will
have to watch the southward progress of these features as they may
serve as a potential focus for additional rain development overnight
and possibly result in a brief wind shift/slightly cooler
temperatures than presently forecast across Central Texas.
Regardless, strong southerly flow will mean a few streamer type
showers develop east of the Interstate 35 corridor ahead of these
boundaries overnight tonight. High resolution guidance has
intermittently shown the outflow or possibly the MCS reaching the
Central Texas counties before sunrise and should this solution pan
out, another round of isolated to scattered showers and
thunderstorms may clip areas generally north of a Mason to San Marcos
to Eagle Lake line during the pre-dawn hours. Have kept a mention of
scattered showers and thunderstorms in the forecast for these areas
overnight with generally dry conditions expected farther west.
Forecast soundings indicate that the cap persists overnight across
the region and expect this to temper the intensity of any activity
that is able to move into the region from North Texas, but stronger
cells may still be capable of a brief hail or gusty wind threat with
observed mid-level lapse rates on both the FWD and DRT 00Z soundings
in excess of 8 C/km.
Persistent southerly flow will also allow lower clouds to fill in
across the region, keeping evening and overnight temperatures warm.
Austin Bergstrom, Austin Mabry, and San Antonio all have the
potential to set or tie record high minimums for May 1 should their
temperatures not fall below 74 degrees through the remainder of today.
Overnight temperatures are only expected to fall into the upper 60s
to lower 70s.
&&
.PREV DISCUSSION... /ISSUED 627 PM CDT Wed May 1 2019/
AVIATION...
Overcast clouds are currently bisecting the area with SCT/BKN VFR
ceilings at AUS and OVC VFR skies at SAT/SSF. DRT has waffled back
and forth between VFR and MVFR through the evening, but generally VFR
skies are forecast into the early evening hours at all terminals.
The greatest chances for precipitation and especially thunderstorms
will be at DRT and AUS through the evening hours with isolated storms
currently ongoing west of DRT. While rain chances should end by 06z
at all terminals ceilings will begin to lower to MVFR and possibly
IFR levels in a few spots. Have kept prevailing MVFR cigs with SCT
IFR mentioned due to uncertainty in how far ceilings will drop and
based on a persistence forecast due to the MVFR ceilings the last
few mornings. Ceilings will be slow to improve during the day
Thursday but VFR should return late in the afternoon. Tomorrow should
only see a few isolated showers and maybe a thunderstorm, not
warranting a mention in the TAFs at this point. Precipitation
chances do begin to increase tomorrow evening so VCTS has been
included in the AUS TAF. Winds will generally be out of the southeast
around 10 knots through this TAF period.
PREV DISCUSSION... /ISSUED 249 PM CDT Wed May 1 2019/
SHORT TERM (Tonight through Thursday Night)...
Forecast this afternoon and evening looks to be drier than expected
with the cap holding on. Most of the convection over the last couple
of hours has initiated well north of the area. CAMs continue to
develop convection over west central Texas into this evening but are
pessimistic on rain chances for our area. The ARW is the outlier
which develops a robust line of storms through the northeastern
parts of the region, but is doubtful with current development. The
last few model runs of the HRRR develops a supercell type complex and
moves it into Val Verde County just after 22Z, but confidence is low
on this actually materializing.
Rain chances hang around for Thursday but remain relatively low for
the period with broad troughing off to the west and in between
pulses of energy that are ejected out over the state from Mexico.
Have kept 30 PoP in for the northern portion of CWA for the day
Thursday. Late Thursday night, the next upper level shortwave
disturbance translates out of Mexico.
LONG TERM (Friday through Wednesday)...
Friday is looking like the best chances for rain in the forecast
period. Persistent southeast flow off the Gulf has primed the region
with elevated moisture and sufficient available energy with forecast
sounding throughout the region holding 2500+ CAPE. The shortwave
disturbance moving over the state Friday looks to put forcing farther
south than previous ones. Timing of convection is highly dependent
on the timing of the shortwave but elevated rain chances exist all
day Friday.
Rain chances push into the eastern CWA and out of the region heading
into Saturday. Shortwave ridging tries to establish itself over south
central Texas late Saturday and into early next week but rain
chances look to make a return Monday as an embedded shortwave moves
over the state once again. Both GFS and ECMWF has this occurring
Monday but may need to reassess PoP chances as this time period gets
closer. Another upper level low approaches from the Pacific toward
the end of the period bringing chances for rain once again.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 72 85 68 80 64 / 30 30 40 70 70
Austin Bergstrom Intl Airport 72 85 67 80 63 / 30 30 40 70 70
New Braunfels Muni Airport 72 85 67 80 63 / 20 20 30 60 60
Burnet Muni Airport 69 82 65 77 61 / 30 30 50 70 60
Del Rio Intl Airport 71 89 68 85 65 / 20 20 50 50 40
Georgetown Muni Airport 70 83 67 79 63 / 40 30 40 70 70
Hondo Muni Airport 72 90 68 83 63 / 10 20 40 50 50
San Marcos Muni Airport 72 85 67 80 63 / 30 20 30 60 70
La Grange - Fayette Regional 73 87 70 83 66 / 30 20 30 60 60
San Antonio Intl Airport 72 87 69 81 65 / 20 20 40 60 60
Stinson Muni Airport 73 87 70 82 66 / 20 20 30 50 60
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Aviation...Treadway
Short-Term/Long-Term...Huffman
Area Forecast Discussion
National Weather Service Hastings NE
620 PM CDT Wed May 1 2019
.SHORT TERM...(This evening through Thursday)
Issued at 344 PM CDT Wed May 1 2019
Aloft: WV imagery and aircraft wind data reveal a longwave trof
over the Wrn USA with a longwave ridge along the E coast. This has
resulted in WSW flow over the Cntrl Plns. A shrtwv trof was over
WY. This trof will lift NE acrs SD into MN tonight. Cyclonic WSW
flow will remain over NEB/KS in its wake tomorrow.
Surface: Wk low pres was over MI with a stationary cold front
extending SW acrs KS to CO. High pres was over the Nrn Plns. This
high will strengthen a bit and drop into NEB tonight. This will
shove the cold front further S and E away from the rgn. The high
will then move NE into MN tomorrow...with a ridge axis still
extending back into NEB/KS.
Tonight: Cldy to start with some light rain mvg thru...primarily
S of I-80. Rainfall amts will be light...probably less than 0.10"
over S-cntrl NEB...and less than 0.20" over N-cntrl KS. Clearing
late as the trof axis passes.
This clearing with light winds/high pres closeby will allow temps
to drop. The prvs fcst had frost acrs the NW 1/3 of the CWA. That
has been removed as conds will be favorable for fog dvlpmt since
temp/dwpt spreads are very low. Even with fog...all guidance fcsts
temps to drop to or a little below frzg (Cambridge-LXN-ODX).
Confidence is high.
Just E of this area (Alma-Kearney-Fullerton/Greeley)...hv
included a mention of patchy frost. Confidence is low. Am not
certain there will be enough time after clearing for deposition/
frost formation. Winds also won`t be quite as low the NW 1/3 of
the CWA. In addition...if fog dvlps (which would be further E
than currently expected)...this would mitigate frost formation.
Thu: Sunny and much warmer...but still a few degs below normal.
Low 60s and light winds will make for a very very nice day.
.LONG TERM...(Thursday night through Wednesday)
Issued at 344 PM CDT Wed May 1 2019
Aloft: The longwave flow is currently dominated by -NAO / -EPO
teleconnections...with blocking ridges over Greenland and the E
Pac. In general...this pattern will not chg much during this time
frame...except a little eastward progression.
One last shrtwv trof will dive into the Nrn Rckys Thu. This trof
will cross the rgn Fri followed by low-amplitude WNW flow Sat-
Sun. Split flow will dvlp as a low (currently btwn HI and CA)
moves E to the CA coast. This should force heights to rise about
60 m over NEB/KS with confluent zonal flow here Mon. Winds should
begin to back to SW Tue as this low slowly inches into the Desert
SW. However...after diminishing for a couple days...the blocking
high over the E Pac will reamplify with tight-clustering among the
global mdls. This suggests that any mdls that try to eject that
low NE acrs the Plns (like the 12Z GFS and GFS-FV3) will probably
be incorrect. SW flow should prevail over NEB/KS into Wed. The Nrn
stream can`t be ignored. A shrtwv trof is fcst to mv E along the
US-Can border Mon night. That will drive a cool front thru here.
Surface: High pres will depart to the E Fri. NEB/KS will be in
the warm sector of low pres mvg acrs Srn Can Fri-Sat. The cool
front associated with that low is fcst to sag into the CWA Sun
AM...and lift back N as a warm front Sun PM. Another push of
chilly air will come out of Canada Sun night and strengthen the
front...which is then fcst to plunge S thru the CWA Mon night.
Chilly Canadian high pres will build in Tue/Wed.
Temps: Back to near normal Fri...then warmer than normal Sat-
Mon...and Mon could be much warmer than normal. If the 00Z/12Z EC
and 06Z GFS are right...our current fcst may be 5-10F too cool.
Widespread 80s will be psbl. Turning much cooler Tue-Wed...and the
fcst may not be nearly cool enough. Can envision highs in the 50s
for parts of the CWA jammed in low stratus.
Precip: An area of stratiform light rain is psbl Fri night as the
trof mvs thru. Then the fcst has multiple time periods of shwrs/
tstms...but this is probably way overdone. Can`t rule out an
isolated shwr/tstm here and there...but most of the CWA will be
dry. The next decent chance for a few tstms will be Mon night.
Some stratiform rain or drzl could occur Wed.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 610 PM CDT Wed May 1 2019
Light rain is showing up on radar and will have minimal impacts
to the TAF sites this evening. MVFR ceilings will scatter out
tonight, which could give EAR some patchy fog/ stratus tomorrow
morning. Right now have a hint BR and stratus in the EAR TAF as
model guidance is suggesting some light fog could occur.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Frost Advisory from 4 AM to 10 AM CDT Thursday for NEZ040-041-
047-062-073-074-083.
Freeze Warning from 4 AM to 10 AM CDT Thursday for NEZ039-046-
060-061-072-082.
KS...None.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Beda
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
819 PM PDT Wed May 1 2019
.SYNOPSIS...01/738 PM.
Marine layer clouds will develop across the coast tonight into
Thursday morning and are expected to clear by the afternoon. High
pressure moves into the area Thursday leading to warming
temperatures through Friday. A low pressure system may arrive over
the weekend with increasing clouds and cooler temperatures.
&&
.SHORT TERM (WED-SAT)...01/819 PM.
Onshore pressure gradients weakened considerably from yesterday
resulting in much better clearing pattern this afternoon and
warmer temperatures. This evening, satellite imagery showing
low clouds beginning to redevelop across the coast. Current ACARS
data showing a marine layer depth around 1500 feet, which is down
considerably from the past few days. As a result, expecting low
clouds to reform across most coastal and valley areas overnight
into Thursday morning for areas south of Point Conception. For
areas north of Point Conception as weak low level offshore wind
component is expected to keep low clouds mostly confined to
the SBA Central Coast. With heights, thicknesses, and boundary
layer temperatures trending upward on Thursday, look for most
inland areas to climb another 3 to 5 degrees, with warmest valley
and desert locations approaching 80 degrees. Little change in
marine layer cloud coverage and temperatures for Friday.
*** From previous discussion ***
The ridge finally starts to shift east Saturday as the low gets
closer and onshore flow increases. The coastal cooling trend will
spread inland and low clouds will as well with later clearing
expected.
.LONG TERM (SUN-WED)...01/136 PM.
Models in better agreement with the track of the cutoff low early
next week with the operational ECMWF trending closer to the last
few GFS runs. Both their ensemble mean solutions are fairly close
as well, though a little slower with the ECMWF. Oddly enough the
GFS actually trended a little drier with this system while the
ECMWF trended wetter, but still very light. Best chances for
light showers appear to be Monday and Tuesday though the track of
the low will have a lot to say about that. Not seeing enough
instability to generate any convection so mainly just either
drizzle or light showers.
Both models now showing a second upper low dropping out of Canada
Tuesday into early Wednesday but differ in the details. Have kept
in shower chances into Wednesday and may have to include Thu as
well if the slower EC solution verifies. Looks like a pretty cool
week with the various cutoff lows around and possible showers.
&&
.AVIATION...02/0017Z.
At 0010Z, there was no marine inversion at KLAX.
Satellite imagery showing mostly clear skies across the forecast
area late this afternoon as onshore flow has weakened considerably
since yesterday. Expect fairly widespread low clouds in coastal
and valley areas later tonight into Thursday morning, with mostly
MVFR conditions.
KLAX...Moderate to high confidence in the 00Z TAF. There is a 20%
chance of MVFR cigs arriving between 03z-06z.
KBUR...Moderate to high confidence in the 00Z TAF. There is a 20%
chance of MVFR cigs arriving between 06z-09z.
&&
.MARINE...01/807 PM.
For the most part, wind and sea conditions are expected to remain
below Small Craft Advisory levels through Sun. However, there is
a 40% chance of SCA level winds across the outer waters Thursday
afternoon and evening, and again Sat into Sun.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
.HAZARD POTENTIAL OUTLOOK (SAT-WED).
No significant hazards expected.
&&
$$
PUBLIC...Gomberg/MW
AVIATION...Gomberg
MARINE...Sweet
SYNOPSIS...Stewart
weather.gov/losangeles