Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/21/21
Area Forecast Discussion
National Weather Service Phoenix AZ
506 PM MST Thu May 20 2021
.UPDATE...00Z Aviation Discussion.
An approaching weather system will lead to breezy to locally windy
conditions through Friday and cooler temperatures into the weekend.
The weather system will also bring increased cloudiness this
afternoon into early Friday morning and likely some lower desert
sprinkles and mostly light high elevation rainfall tonight. Lower
elevation high temperatures will fall well below normal into the
80s for Friday and Saturday before warming back to or just above
normal readings starting early next week.
Current METSAT and upper air RAP H5 analysis shows the large low
pressure system pushing well through the Pacific NW along with its
strong jet streak and PVA anomalies. Semi-moist W-SW flow was
noted aloft as a swath of high clouds and elevated WV was
advancing into the region from the W-SW in advance of a EPAC
shortwave disturbance south of the main low. Current ACARs
soundings exhibit the W-SW flow aloft with indications of upper-
mid level moisture advection near 600 mb. Light radar returns were
seen moving across N Baja. The column was stable and PW was on
the rise and passing through 0.5". Today expect a degree or 2
cooler than yesterday with a highs in the upper 90s to 100.
The upstream, strong closed low pressure system will continue to dig
towards the region through the Western US through Saturday with the
base of the trough settling over N Baja. The system will usher in
cooler temperatures and breezy to windy conditions, especially
out west where patchy and lofted blowing dust is a concern through
tomorrow. As a result a wind advisory remains in effect for parts
of SE CA including Imperial Cty, in the west CWA. There is also a
Red Flag warning for this afternoon and evening for the Lower
Colorado River valley for critical fire weather conditions
A pre-system weak PVA disturbance with a moderate IVT moisture plume
slips in around the base of the system tonight and provides our
slight chance of rain late tonight and the first part of Friday
morning. As far as QPF goes the GFS and GEFS now features a
modest amount of QPF for the E CWA as they get a better handle on
that moderate IVT moisture plume.
HREF family members agree on mostly light rain with the next
system from this evening to the first half of Friday morning. No
real outliers today, although the HRRR became the most bullish on
some embedded heavier showers late tonight in and around the NE
Phx valley. Forecast soundings and HREF CAPE forecasts indicate
stable conditions and almost no CAPE due to the offset position of
the low and colder air displaced well to the NW. Also theres a
bit more moisture in the lower mid levels now extending down to
near H7 and fairly dry below that. The result now is at least for
some low QPF for some models and WPC. For most of Friday and into
the weekend the system will feed drier air into the region as
POPs quickly and substantially diminish west to east.
Highs for the weekend will fall to near 10 degrees below normal in
the low 80s out west to the mid to upper 80s around Phoenix. The
clusters and ensembles analysis/forecast agree that the low will
begin to eject by mid weekend and into early next week towards the
northeast into Montana in all scenarios. As it does heights will
recover and high temperatures will warm back up to near normal in
the upper 90s by Mon-Tue. Some weak dry cyclonic troughing will then
dominate the region well into next week.
.AVIATION...Updated at 0005Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
West-southwest winds will increase in speed through this evening.
Gusts will peak between 23-06Z potentially exceeding 30 kts at
KPHX & KDVT, while only reaching the mid-upper 20s at KIWA & KSDL.
Gusts are anticipated to taper after 06Z but winds will stay
elevated through the overnight hours and likely not transition to
an easterly wind but be more southerly. Gusty day again tomorrow
afternoon but wind gusts should remain slightly below today`s
levels. Clouds will continue to increase in coverage and lower
through the period as we are likely to see a BKN deck around 100
by 06Z. Around this time, there could also be a layer of clouds
near 7 kft. Cloud cover will start to improve as we head into the
morning and afternoon hours tomorrow. Low chances (10-20 percent)
for isolated showers and virga across the valley from 07-12Z
before drier air pushes in. Due to lower confidence on coverage,
leaving out of TAF package at this time.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will be the primary aviation weather concern through the TAF
period. Wind gusts as high as 35 kts at KIPL and closer to 40 kts
at KBLH through 04/05Z. At KIPL, gusty conditions will be present
for the remainder of the TAF period, with gusts dropping closer to
25-30 kts overnight before increasing close to 30-35 again
tomorrow afternoon. At KBLH, gustiness will subside after
midnight, but increase again tomorrow afternoon with gusts close
to 30 kts. These gusty winds will cause periods of blowing dust
and reduced visibilities. Lofted dust may also cause slantwise
Sunday through Thursday:
Very dry conditions with periods of breezy winds are expected
through the period. A dry, weakening weather system departs on
Sunday leaving lighter winds, but with some afternoon gusts to 20
mph still possible Sunday through Wednesday. Min RH levels will
stay near 4-8% through the period, while overnight Max RHs will
mostly fall within 15-30%.
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
AZ...Red Flag Warning until 8 PM MST this evening for AZZ131.
CA...Red Flag Warning until 8 PM PDT this evening for CAZ231.
Wind Advisory until midnight PDT tonight for CAZ563>567.
Wind Advisory until 9 AM PDT Friday for CAZ562.
Area Forecast Discussion
National Weather Service Blacksburg VA
721 PM EDT Thu May 20 2021
High pressure will dominate the weather pattern over the eastern
part of the country for the next several days. This will bring
a stretch of generally dry weather and summerlike warmth to the
region through the weekend. Afternoon showers and thunderstorms
may return early next week as a cold front sags in from the
.NEAR TERM /THROUGH FRIDAY/...
As of 720 PM EDT Thursday...
Big Bubble = No Trouble.
A large dome (bubble) of high pressure will be the dominant
weather feature through Friday. Friday`s weather will be almost
identical to Thursday. Aside for some thin cirrus clouds
blanketing the area, it will remain rain-free. Current 850 MB
temperatures range between 13C-16C and will increase a degree
warmer tomorrow. This will translate to surface temperatures in
the mid 70s to lower 80sF across the mountains and mid 80s to
upper 80s east for daytime highs. Lows for the time being (due
to the low dewpoints) will cool off quite nicely for the
overnight period with minimums in the 50s... upper 40s in the
colder mountain valleys.
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 140 PM EDT Thursday...
Summery weather through the weekend.
Ensemble guidance is consistent in showing the large upper ridge over the
eastern US gradually retrograding a bit and starting to deamplify as we head
into the weekend. This will allow short wave energy to spill down and as the
surface high follows the ridge, and front will start to sink in our direction
from the north. However it appears the influence of the ridge will be strong
enough across the Appalachians and central mid Atlantic region to keep the
front at bay for a while longer. The net result will be continued summerlike
warmth and generally dry weather, though humidity will be steadily on the
increase and an isolated shower may pop up as we head into the back half of the
Expect highs this weekend to be in the middle 80s to around 90 degrees east of
the Blue Ridge with low/mid 80s to the west. Over night lows will be mild as
readings trend from generally in the 50s Friday night to generally in the 60s
by Sunday night.
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 140 PM EDT Thursday...
Remaining warm with a chance for showers and thunderstorms returning for
the first part of next week.
A more progressive pattern is taking shape as ensemble guidance remains
consistent in the extended showing overall deamplification of the blocky
pattern over the lower 48. While there are no signals for significant
widespread precipitation, as the ridge flattens a better supply of short wave
energy will bring more in the way of scattered showers and thunderstorms to the
region through the first part of next week.
Temperatures will remain well above normal through the period.
.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
As of 720 PM EDT Thursday...
High pressure dominates surface and aloft so a high confidence
aviation forecast through the remainder of the week with VFR
conditions prevailing. Any patchy fog/stratus that develops
during the early morning hours will be mainly confined to the
deeper river valleys and burn off quickly after sunrise. Winds
will be light with little impact to aircraft operations through
Extended Aviation Discussion...
High pressure and VFR conditions prevail for the remainder of
the week and into the weekend. Patchy fog may develop in
mountain river valleys most mornings, but the overall trend is
for drying with little to no rain until next week.