Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/30/22
Area Forecast Discussion
National Weather Service Indianapolis IN
1015 PM EDT Wed Jun 29 2022
...Updated Aviation Discussion...
.Forecast Update...
Issued at 954 PM EDT Wed Jun 29 2022
In the immediate short term, the forecast across the central Indiana
remains on track. On the larger scale, a broad high pressure system
is exiting the Ohio River Valley, ushering in weak and generally
southwesterly flow at the surface. The marginal magnitude of these
surface winds plus subsidence aloft due to the location of the upper
ridge are prohibiting any significant moisture advection from
occurring. Speaking of upper levels, northwesterly flow aloft should
become more zonal throughout the night, and ACARS soundings
continue to show dry air through the entire column. Given the light
surface winds and dry PBL, diurnally-driven radiational cooling
should allow temperatures to quickly drop into the mid to lower 60s
overnight. With dewpoints relegated to the mid 50s as a result of
the aforementioned subsidence and lack of moisture advection, it is
evident that the Indianapolis CWA is in for yet another cool, clear
night.
&&
.Short Term...(This evening through Thursday night)
Issued at 245 PM EDT Wed Jun 29 2022
...Increasing fire threat as hot, dry conditions persist...
...Chance of rain and storms returns by the weekend...
While a pattern change is on the horizon, expect hot and dry
conditions to continue for the latter half of the week. Current
surface analysis this afternoon shows high pressure off the East
Coast stretching all the way into the Central Plains while low
pressure develops on the leeside of the Northern rockies. Very dry
airmass in place over the Ohio Valley for this time of year with dew
points struggling to hit the 50 degree mark and RH values this
afternoon down near 30 percent. Little to no return flow off the
Gulf and subsidence directly under the high are responsible for
keeping conditions as dry as they are. Current IND ACARs soundings
show very dry air through the column, so any mixing that does occur
will help to further dry the surface. Light winds and a dry PBL will
make for optimal conditions for radiational cooling tonight as
temperatures quickly fall into the low 60s.
One more dry day on Thursday before a pattern change begins to take
shape across the eastern half of the CONUS. Upper level ridging
shifts eastward over the Northeast while a deep upper low over
Central Canada dives south leading to broad troughing developing
across the Great Lakes region by the end of the week. Surface low in
Western Ontario occludes during this time frame with its trailing
cold front extending southwest towards lower pressure near the Front
Range. This front will be the focus for shower and thunderstorm
development on Friday; however high pressure will continue its
strong influence over the region for one more day.
As the surface high shifts east and the front approaches from the
north, the pressure gradient tightens leading to elevated southwest
flow Thursday with gusts up to 15 to 20 kt. Short term model
soundings depict mixing heights upwards of 5,000+ feet into a layer
of very dry air aloft tomorrow afternoon. Expect gusty winds to help
bring dry air down to the surface keeping dew points and RH low
during peak heating of the day. Continued subsidence under the high
and WAA aloft (850 mb temps rising to around 20C) should lead to
highs in the lower 90s regionwide. Keeping an eye on the heightened
fire risk during the afternoon hours with elevated winds and
potentially very low RH values under 30 percent. Fuels and soil
moisture are already very dry for this time of year as much of the
region is 2.5 to 3.5 inches below normal for rainfall just this
month. The fire threat will be something to monitor tomorrow;
however do not think it will persist as rain and storms return to
the forecast for this weekend and next week.
Gulf moisture streaming northward ahead of the approaching front
will make conditions feel significantly more humid overnight. Once
mixing shuts off around sunset, southwesterly surface flow will pump
in moist air leading to dew points rising from the lower 50s to near
70 by sunrise Friday. Increasing high level clouds and overall
moisture content will prevent temperatures from significantly
falling overnight as well with lows bottoming out around 70 degrees
across Central Indiana.
&&
.Long Term...(Friday through Wednesday)
Issued at 245 PM EDT Wed Jun 29 2022
...Quiet weather pattern comes to an end...
...Storm chances increase on Friday...
...Unsettled weather into next week...
Friday
A large upper-level ridge currently over the region will gradually
begin to break down Thursday night as a strong but fast-moving
surface low skirts across the US Canadian border. A cold front
associated with the low will then sag southward into Friday. While
the ridge is suppressed a bit, faster zonal flow aloft will remain
mostly across the northern half of our CWA. As the front drops
south, it should slow and then stall as the parent low occludes then
departs to the east. Convective potential with the front depends on
timing and how strong this boundary is when it arrives.
The overall set up appears to be a bit disjointed, with the best
upper-level support in the northern half of the CWA and the best
instability further to the south. This slight misalignment of
dynamics and instability may have some implications on resulting
convection, including storm organization and severe potential. As of
right now, the greatest chance of storm activity will be across our
northern counties. Here, fast upper-level flow aligns best with the
warm unstable air ahead of the front. Guidance characterizes this
environment with effective along-boundary shear over 35 kts, MLCAPE
over 2000 J/kg, and modest lapse rates. Additionally, a very dry
layer of air around 600 mb is shown. Should thunderstorms initiate
along the front, rapid upscale growth into cold-pool dominant
clusters is favored with damaging winds being the primary hazard.
Though some isolated large hail would be possible early on before
storms consolidate.
Any storm clusters should then propagate southward into greater
instability and low-level flow, but generally weaken as diurnal
heating is lost. Long-track MCS propagation is not expected due to
weakening mid to upper-level flow. The front itself, however, will
continue to track southward while gradually slowing down.
Saturday and Sunday
The nearly-stalled front should be most of the way through our CWA
by saturday morning. Showers and thunderstorms may persist into
Saturday, maintaining the continued weakening trend from Friday
night. Ensembles have the front reaching our southern border, near
Vincennes, before stalling completely. At the same time, the western
portions of the front should begin to return north as a warm front.
Surface high pressure north of the boundary will act to keep things
fairly quiet across most of northern Indiana late Saturday into
Sunday. Best chance of showers remains along the front. The GFS
wants to bring a wave along the boundary, enhancing precip potential
into Saturday, though this is an outlier. Will keep PoPs in slight
to chance category through Sunday, with greatest chances in the
south since the front will be nearby.
Monday through Wednesday
By Monday, some additional shower and storm development is possible
as weak isentropic lift develops along the now advancing warm front.
In the upper-levels, northwesterly flow begins to take shape as the
upper-level ridge redevelops and amplifies along the front range of
the Rockies. Northwesterly flow should allow the advancing warm
front to slow while taking on a northwest to southeast orientation.
Such an upper-level pattern directs shortwaves up and over the ridge
then southeastward towards the Ohio River Valley. A set up favorable
for southeasterly propagating mesoscale convective systems. In fact,
a multitude of model guidance hint at this possibility, though
details and timing differ. Regardless, rain and thunderstorm chances
will remain elevated through the end of the long range.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1015 PM EDT Wed Jun 29 2022
IMPACTS:
* None.
Discussion:
High pressure over the region will keep near ideal flying conditions
in place across central Indiana airfields. Winds will generally be
south or southwesterly although they will likely be variable at
times. Speeds will be below 10KT throughout the period with only a
few passing high clouds and unrestricted visibilities.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Update...Marcus/Nield
Short Term...CM
Long Term...Eckhoff
Aviation...Nield
Area Forecast Discussion
National Weather Service Phoenix AZ
418 PM MST Wed Jun 29 2022
.UPDATE...UPDATED 00Z AVIATION DISCUSSION.
&&
.SYNOPSIS...
During the latter half of the week, thunderstorm coverage will
gradually shift towards higher terrain locations north and east of
Phoenix. Then, a drying trend will become increasingly likely across
the entire area during at least the first half of next week with
little to no thunderstorm activity. Slightly above normal
temperatures should retreat closer to the seasonal average through
the holiday weekend before warming again into the middle of next
week.
&&
.DISCUSSION...
Early afternoon WV satellite imagery shows the anti-cyclone center
has shifted along the CO-NM border with deep southeast flow becoming
established across the forecast area. While the primary inverted low
pressure system has stalled over NE Mexico, a smaller, more subtle
shortwave was embedded in the SE flow over northern Sonora creating
convectively favorable upper level divergence over the southern half
of Arizona. Objective analysis and in situ ACARS soundings indicate
MLCape has increased to near 1000 J/kg, albeit with notable
inhibition still relevant around the top of the boundary layer.
However, robust thunderstorm development began in parts of the state
as early as 17Z in the face of this rather large CinH suggesting
enhanced forced ascent capable of breaching this inhibition.
With DCape increasing near 1500 J/kg, any thunderstorms in this
environment will be capable of producing strong downburst wind gusts
and organized outflow which will rapidly help invigorate additional
storm development (especially given the surrounding good synoptic
scale lift). The culmination of multiple large outflow boundaries
will support areas of blowing dust across the dust prone areas of
Pinal, Maricopa, La Paz, and Yuma counties. Accumulating rainfall
will be more difficult to come by with NBM probabilities of
accumulations exceeding 0.10" just under 35%. Therefore, the flood
threat appears low at this time, although cannot be totally ruled
out, especially if there are training or consolidation of storms
behind an outflow boundary.
Even though HREF ensemble has not been particularly aggressive
with storm coverage this afternoon, the aforementioned parameters
may argue for better convergence and clustering of numerous storms
through western Maricopa County this evening. A period of greater
foreast uncertainty exists Thursday morning as a handful of CAMs
(including several HRRR iterations) have produced expansive
midlevel accas showers/embedded storms over (or around) the
Phoenix metro. These type of scenarios are forecast by CAMs
frequently in the monsoon, however only come to fruition a
fraction of the time though remains a 20% chance of occurring
based on analysis of forecast details. Aside from this
possibility, activity Thursday afternoon should begin the retreat
to high elevations with a more hostile environment for deep
convection developing in the lower deserts. Long traveling outflow
winds will still be possible into lower elevation communities
with NBM POPs dropping below 15%.
The hemispheric synoptic pattern towards the end of the week will
feature a deepening trough situated off the west coast. This will
result in increased southwesterly flow impinging into the SW Conus
and resulting in a gradual shift of better quality moisture
eastward. As a result, the better chances of storms Friday will be
confined mainly to the higher elevations zones located north and
east of Phoenix, where NBM PoPs fall in a 30-40% range while lower
elevations fail to even register 10%. The aforementioned west coast
trough deepens even further during the weekend through early next
week, and the moisture plume will likely be pushed further east into
extreme eastern Arizona and New Mexico. The vast majority of the
CWA, including higher terrain areas, should expect little to no
storm activity with NBM POPs barely registering 20% anywhere within
the forecast area starting Sunday.
Temperatures through the end of the week and holiday weekend will
slightly cool into a seasonally normal range as 500 mb heights dip
slightly due to the influence from the developing west coast trough.
This trough will eventually lift away from the region during the
middle of next week, and the preponderance of model evidence points
towards subtropical ridge retrogression and intensification over
the area during the latter half of next week potentially resulting
in a period of excessive heat before the wetter portion of
the monsoon pattern reloads.
&&
.AVIATION...Updated at 2315Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
A strong outflow boundary is currently moving out of the metro
area with all sites now observing southerly wind. Dense blowing
dust is occurring with this boundary, but visibilities should
begin to recover over the next hour. Scattered thunderstorms
resulting in erratic wind shifts will continue to be possible for
the next few hours. Cloud bases should remain near or above 10
kft. Overnight, winds will favor the southeast but may be variable
at times. An additional uptick in shower activity is possible
after 10Z on Thursday morning but any showers should diminish by
late morning. Winds will shift to southwest by Thursday early
afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds at KIPL will favor the west this evening with some gustiness
this evening and again Thursday evening. Winds may shift to
southeast on Thursday morning for a few hours. At KBLH winds will
mostly favor the southwest with some gustiness developing Thursday
afternoon. A few clouds are expected, but mostly above 10kft.
&&
.FIRE WEATHER...
Thunderstorm activity for the remainder of the week will be mostly
confined to higher terrain locations north and east of Phoenix.
Mainly dry conditions, even across the higher terrain, is becoming
increasingly likely during at least first part of next week as drier
air overtakes the area. Afternoon humidity values will range between
15-30% through the rest of the week, then decrease closer to the 10-
25% range early next week. Overnight recovery will generally be 25-
50% over lower elevations and 50-80% over the higher terrain of
eastern districts. Increased southwest winds will begin to become
more common over western districts this weekend, but remain well
below critical thresholds. Otherwise aside from thunderstorm
outflows, winds in eastern districts should not pose problems.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...18/Lojero
AVIATION...Hodges
FIRE WEATHER...Lojero/18