Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/30/21
Area Forecast Discussion
National Weather Service State College PA
950 PM EDT Tue Jun 29 2021
.SYNOPSIS...
An anomalous upper level ridge will remain centered off of the
Mid Atlantic coast through the middle of this week. A slow
moving cold front will then likely push southeast across the
state Wednesday night and Thursday, with upper troughing
remaining over the region into next weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Strong upper level subsidence associated with subtropical ridge
has largely suppressed convection across central Pa late today.
Isolated pulse type convection over the central part of the
state should diminish with loss of heating this evening.
However, a weak mid level vort max is progged by latest RAP to
lift northeast across Lk Erie, bringing a chance of showers/tstorms
across Warren/Mckean counties through late evening. Will
maintain just a slight chance of lingering showers after
midnight across the northwest corner of the forecast area,
along plume of higher pwat preceding approaching upper trough.
As occurred last night, mostly clear skies, calm wind and
abundant low level moisture should promote patchy fog across the
central mountains, mainly in the deep river/stream valleys of
north central Pa. The latest HREFV3 and NAMNest both target this
area for the best chance of fog.
Latest GEFS plumes indicate low temperatures should be very
close to those of last night, ranging from the upper 60s across
the Alleghenies, to the mid 70s over the Lower Susq Valley.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
Wednesday is still targeted as an active day as falling heights
ahead of approaching cold front over the Great Lakes leads to
building clouds and convection during the afternoon, especially
across the NW Mtns. Increasing mid level flow and associated
deep layer shear with fairly straight line hodographs in the
lowest several KM AGL will support a chance of organized line
segments with a Slight Risk for severe wx across most of our
CWA, except for the southern tier that will be under a MRGL Risk
for more isolated severe convection. Instability and high pwats
suggest any tstorms will be accompanied by brief torrential
downpours. However, the wettest members of the latest HREF
only support isolated amounts to 2 inches and a limited threat
of flash flooding.
Cloud cover and convection should result in high temps a couple
degrees lower across northern PA Wednesday, while the heat
continues unabated across the southeast part of the forecast
area with heat indices reaching around 100F once again.
Wednesday will be the last day this week of uncomfortable heat
indices.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Wednesday night convection may continue during the evening into
the night as series of shortwaves move eastward through the base
of a deepening upper level trough.
The upper through will continue to progress and deepen Thursday
into Friday, with more rounds of showers and thunderstorms
likely. A weak surface cold front will begin to cross the
region Thursday. The front will likely reach our southeast
areas by Thursday afternoon at peak heating, which may result in
more storms Thursday afternoon. Both the GFS and EC have a
closed upper low over the Ohio Valley for the weekend, but the
evolution of this feature differs between models. In either
case, the closed low will bring gulf moisture into our area so
storms that fire may produce heavy rain. Due to uncertainty,
kept chances of showers and afternoon storms to continue
through Sunday.
The cold front passage Thursday coupled by persistent cloud
cover and rounds of showers and storms will keep temperatures
below average for the end of the week into the weekend.
Monday and Tuesday look warmer and drier as the closed low
slides off the Atlantic coast, but this may change depending on
what happens with the low over the weekend.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Latest radar trends support continuing/adding VCSH to all TAF
sites except BUF and LNS, through 00Z.
For now, expect fog to be limited overnight.
Earlier discussion below.
VAD winds and winds on 12Z observed soundings a little more
northwest today, with less CU so far, and still very warm air
aloft, so hard to see much in the way of showers today.
Main change late this morning was to back off storms at BFD
at 00Z this evening, looks like most everything with the cold
front would still be well to the north and west at this time.
Temperatures in the upper 80s to mid 90s will result in higher
density altitudes both today and tomorrow.
Clear skies will prevail overnight and patchy fog will be
possible once again Wednesday morning, especially where rainfall
occurs this afternoon and evening.
Outlook...
Wed...More in the way of showers and storms, especially during
the late afternoon into the evening.
Thu...Showers and storms look to be rather widespread.
Fri-Sun...Still a daily chance of showers and storms, mainly
afternoon into early evening.
&&
.CLIMATE...
Record high minimum temperatures were set at MDT on Monday and
this morning:
The low temperature on Monday 6/28 was 76, breaking the old
record of 74 set in 1901. The low temperature this morning
(6/29) was 79, breaking the old record of 75 set in 1991.
Another daily record low temperature record is in jeopardy
Wednesday at MDT:
Min Temp Fcst Old Record
6/30: 7574 in 2017
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon to 7 PM EDT Wednesday for PAZ046-
049>053-057>059-065-066.
&&
$$
SYNOPSIS...Lambert/DeVoir
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Wagner
AVIATION...Martin/Gartner
CLIMATE...
Area Forecast Discussion
National Weather Service Gray ME
946 PM EDT Tue Jun 29 2021
.SYNOPSIS...
After a very warm and humid night tonight...a cold front
dropping towards New England from Canada will bring scattered
showers and thunderstorms to the region Wednesday afternoon and
evening with severe weather possible. Dangerous heat indices
will again be possible south of the mountains on Wednesday
before somewhat cooler air moves in Wednesday night. A
cooler...and unsettled pattern is expected through the end of
the week and into the Independence Day weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
945 PM UPDATE... Made some very minor adjustments to
temperatures, dew points, winds, and sky cover to better align
with observations and satellite imagery. It will continue to be
a very warm and muggy night with overnight lows only falling
into the 70s in most locations. The rest of the forecast remains
on track.
8PM UPDATE... Most of the highly scattered thunderstorms this
evening have dissipated in our area, although regional radar is
still lit up in other areas. Generally expect convective trend
in the region to continue to decrease and think our area will
likely be dry for the next several hours at least. Made only
minor adjustments to precipitation chances and
temperature/dewpoint trends based on latest observations.
ORIGINAL DISCUSSION...
High Impact Weather Potential: Some potential for thunderstorms
to near far northern zones after midnight.
Pattern: Sprawling mid level ridge / Bermuda High remains
centered along the US East Coast with cutoff high centered over
the Pacific northwest responsible for the record shattering heat
in that region. between these features is a shortwave trough
that is moving into the western Great Lakes region. Ahead of
this feature is a plume of deeper moisture that originates in
the western Gulf of Mexico... arcing around the East Coast high.
The evolution of convection firing ahead of this trough and
whether it will make a run at our forecast area tonight is the
primary forecast challenge.
Through this Evening: Another hot and humid evening is in store
as temperatures slowly retreat from afternoon highs. Outside of
an isolated shower...should be predominately partly cloudy and
dry across the region with 8pm temperatures in the upper 70s in
the mountains with mid 80s to the south and east.
Tonight: Outside of having eyes on convection...another
warm/humid night is expected with a very similar outcome to last
night. Boosted overnight lows some for southern areas with some
mid and upper 70s possible in the warmest locations. As for
precipitation potential...developing shower/thunderstorm
activity north of Lake Ontario will struggle to survive as it
lifts north and east into a lower dewpoint airmass and the CAMs
have been pretty consistent in this activity not surviving. More
interesting is possibly the convection over lower Michigan
which some of the morning/early afternoon HRRR runs maintains
some organization as it makes a run at northern New England
after midnight. Will include chance PoPs over the northern zones
to account for some potential though expect any convection to
be in a decaying mode and therefore see little severe threat.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
High Impact Weather Potential:
* Severe thunderstorms possible Wednesday afternoon and evening.
* Heat indices reach advisory levels again for SE NH / SW ME.
Wednesday: Mid level shortwave centered over the Great Lakes
will move east through the day with a very weak wave of low
pressure taking shape to it/s east over northern Maine during
the morning as height falls associated with the upstream wave
move overhead. By noon...surface cold front will be aligned west
to east still north of New England with a pre-frontal trough
along the coastal plain. Height falls and right entrance region
of 100kt jet at H2 align well with a ribbon of 50+kt winds
arriving at H5 suggesting organized storm modes are possible as
cooling temps aloft and our hot/humid airmass allowing MLCAPEs
to reach 1000-1500J/kg. Surface forcing with the associated
front/trough is not well aligned with the llevel instability
axis so am not surprised that today/s CAMs are offering a
variety of potential outcomes. Single/multi cell clusters
evolving into small lines as cold pools combine appears likely
with confidence still not high on overall extent given
disjointed surface forcing. Feel confident that we/ll see some
severe weather...with damaging winds likely the greatest threat
with rotating updraft potential also suggesting a hail threat
despite the warm airmass. The tornado threat is lower...with
somewhat elevated LCL heights and unidirectional wind profile
with the overall orientation of the forcing mechanisms largely
parallel to the 0-3km shear. If more of a N/S oriented
convective structure can develop along the line of storms...an
isolated tornado would not be out of the question. Given this
shear orientation to the line...a flash flood threat exists as
some training would be possible...but confidence in this is also
lower given uncertainty in overall convective coverage.
Temperatures: T8s/T9s will be no cooler than today on Wednesday
morning with our primary limiting factor being cloud cover which
will certainly keep temperatures lower over the mountains. With
some sun through at least the morning over southern zones...will be
reaching heat advisory criteria by late morning for
southeastern NH into far southwestern ME with mid 90s likely
given current sky cover expectations. Have issued a heat
advisory for a slightly smaller area tomorrow...leaving out
portions of the mid coast ME and SW NH...but otherwise similar
to today.
Wednesday Night: Cold frontal boundary slowly sags south across the
forecast area overnight. While the pre-frontal trough responsible
for our Wednesday convection will be south of the region...expect
that we may still see some convective development along the front
itself during the evening depending on how much afternoon /early eve
convection is realized on Wednesday. Beyond this...dry advection
pushes deep moisture south of the region overnight with any shower
activity coming to an end. The night will still be rather warm...
particularly over the southern half of the area where the front
will not really arrive until daybreak. Here...lows in the 70s
will again be common...will values falling towards 60 in the
mountains.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Canadian troughing will push southeastward into New England
late this week, which will bring an end to the ongoing heat wave
over our forecast area. The boundary separating the hot and
humid air mass to the south and a cooler, somewhat drier air
mass to the north will gradually drop south of the area
Thursday into Friday... before stalling over southern New
England. Cut off low pressure to the west keeps conditions
unsettled through the weekend. A blocky pattern leads to fairly
low confidence this weekend and beyond, but overall we`re looking
at a fairly showery period, though not a washout, with
temperatures moderating back to around normal... or even a
little below in some scenarios.
Long range models are coming into better agreement with the
progression of a surface trough and associated cold and dry
advection over New England through the end of the week. By
Thursday, cold advection in westerly to northwesterly flow will
be underway in the wake of the surface trough crossing into the
Gulf of Maine. This doesn`t quite give us the air mass change
we`re desperately seeking with dew points remaining elevated in
the 60s... although ambient temperatures will only warm into the
70s to low-80s, which is a welcome improvement regardless.
Showers can be expected near the frontal zone as it stalls near
the coast, extending back roughly along the Mass border... and
over the higher terrain where cyclonic flow associated with the
trough aloft is present. A few stray showers can`t be ruled out
elsewhere. Diurnal instability may pop a thunderstorm or two
near the frontal zone over the southern zones.
Later Thursday into Friday, troughing over the Great Lakes
amplifies and lurches toward the east coast... spurring
cyclogensis along the primary frontal zone over the Mid-Atlantic
into southern New Hampshire. This accomplishes a couple
things... first, shower activity is renewed along the front with
a steadier, stratiform rain possible for southern and some
coastal areas late Thursday into Friday morning. Second,
cyclogenesis pulls around a northeasterly ageostrophic wind in
the form of a back door cold front. This feature should knock
temperatures and dew points back by several degrees each with
the first comfortable, open-window overnight of the week
Thursday night. On Friday, highs will generally land around 70
degrees, although onshore flow and low clouds could keep some
locations in the mid- 60s... and more sunshine could allow a few
extra degrees of warmth. The front may not make it all the way
south to the Mass border, but showers and clouds should keep
those areas similarly cool though more humid. This entire
scenario may shift N/S by a couple hundred miles depending on
where the primary frontal zone stalls and then amplifies.
For the coming holiday weekend, attention turns to the
progression of our upper level trough which closes off over
Central Appalachia and spins up and over the northeast by the
start of next week - a general progression the long range models
have surprising consensus over. This pattern lends itself well
to continued shower activity, especially as the closed low moves
overhead, but we`ll likely see a break with brief ridging
before this occurs... sometime in the Sat PM/Sun AM time frame
as consensus solutions time out at this stage. The notable
exception to this consensus is the 12Z GFS... which brings a
Nor`easter of sorts through the Gulf on Saturday... but this is
nearshore track is generally an outlier. Regardless of consensus
the blocky pattern leaves a requisite uncertainty when it comes
to timing out these features. This leaves a slight chance to
chance of showers throughout the weekend with greatest
likelihood of showers over the higher terrain where elevated
heating offers a little more in the way of forcing, and along
the coast closer to the low pressure track. Temperatures will
likely settle right around normal for the year, with greater
southerly flow ahead of the approaching low leading to a modest
warming trend to start the next week.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Short Term...
Summary: High pressure will remain in control through early
Wednesday before a cold front dropping towards the region will
bring showers and thunderstorms Wednesday afternoon and evening
before pushing south of the region by early Thursday morning.
Restrictions: VFR across the region early this afternoon are
expected to dominate the TAF period through 18Z Wednesday.
Beyond this...showers and thunderstorms primarily in the 18Z
Wednesday through 02Z Thursday timeframe will bring the
potential for scattered MVFR/IFR restrictions with some storms
having the potential to be severe with hail and strong winds.
Behind these storms haze/fog have the potential to bring
additional restrictions Wednesday night throughout the
region...but especially HIE/LEB.
Winds: Westerly winds 10G15kts will diminish to less than 5kts
tonight before strengthening again from the west around 10kts
for the day on Wednesday. Winds will again diminish to 5kts or
less Wednesday night.
Lightning: As mentioned above...primary threat of lightning is in
the 18Z Wednesday through 02Z Thursday timeframe. There is much
lower potential for an isolated thunderstorm near HIE after midnight
tonight through daybreak Wednesday.
LLWS: No LLWS is expected through Wednesday night outside of
thunderstorm areas.
Long Term...An unsettled pattern continues throughout the long
range portion of the forecast with areas of low pressure
delivering rounds of showers to terminals Thursday and through
the weekend. While periods of MVFR/local IFR in SHRA/RA will be
possible everywhere, chances for restrictions are greatest for
the coast and southern areas... especially late this week.
Specifically, Thursday into Friday could see a prolonged period
of low ceilings for southern and eastern terminals depending on
storm track. For winds, northwest winds on Thursday will veer
northeasterly by Friday, munitioning that general direction
through the weekend.
&&
.MARINE...
Short Term...Winds and waves are expected to remain below SCA
levels through Wednesday night. There is the potential for
strong to severe thunderstorms over the waters Wednesday
afternoon and evening.
Long Term...A trough of low pressure settles over the waters
late this week with light offshore winds. More organized low
pressure centers will form and move along this zone with winds
turning northeasterly through the weekend, delivering
occasional rounds of rain showers. These passing systems may
briefly bring seas to around 5 ft over the outer waters, however
wind fields should remain fairly weak.
&&
.CLIMATE...
Here are some high temperature records for today (6/29):
KCON 97 in 1944
KPWM 96 in 1944
KAUG 90 in 1997 - Broken
Here are some high temperature records for Wednesday (6/30):
KCON 97 in 1964
KPWM 96 in 1971
KAUG 97 in 1971
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory from 11 AM to 8 PM EDT Wednesday for MEZ018>021-
023>025-033.
NH...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NHZ006-
008>015.
MARINE...None.
&&
$$
NEAR TERM...Kimble/Tubbs
SHORT TERM...Arnott
LONG TERM...Casey
Area Forecast Discussion
National Weather Service Wichita KS
935 PM CDT Tue Jun 29 2021
.UPDATE...
Issued at 932 PM CDT Tue Jun 29 2021
A weak meso induced vort center (MCV) swung north and produced some
low popped showers, just to the east of Wichita this evening,
Otherwise, showers have waned somewhat as the afternoon heating
ends. But as the late evening continues, latest RAP model shows low
level moisture transport ramping up again after midnight, which will
lead to the showers redeveloping or moving back into the area from
the south and increasing for areas along and east of the KS turnpike
overnight through early Wed morning. Pockets of heavy rainfall will
remain possible, so will keep the flood watch going even with the
diminished showers for the evening hours.
The 850-700h low level moisture transport will continue for areas
east of the KS Turnpike into Wed morning, but the moisture transport
wanes some for the daylight hours on Wed. Current pops look on track
but may need to be cut back some if showers become widely scattered.
200 percent of normal precipitable water values will lead to very
efficient rainfall producers with any shower that develops, even
from low the topped convection. As Wed morning continues, could even
see a few thunderstorms, as instability increases to 500-1000 j/kg
during peak heating on Wed.
Ketcham
&&
.SHORT TERM...(This evening through Friday night)
Issued at 322 PM CDT Tue Jun 29 2021
While the axis of most numerous showers and pockets of heavy
rainfall has panned out along the turnpike corridor today, so far
rainfall rates and amounts have only result in minor urban street
flooding in the Wichita area. Isolated, diurnally driven, deeper
convection was noted over central Kansas. There appears to be a
vorticity center over Oklahoma which will move northward into
southern/eastern Kansas later this evening and overnight which
may increase coverage of showers and heavy rainfall along and east
of the turnpike. The high PWAT airmass will remain in place
through Wednesday with the better coverage of showers again
expected across portions of south central and southeast Kansas.
Therefore after collaboration with WFO TOP/EAX, have decided to
expand the Flood Watch through Wednesday afternoon. As an upper
trof drops southward across thew Great Lakes Thursday into Friday,
the effective low level/surface boundary and higher PWAT air will
be shunted south of the area. So, will continue to carry some
PoPs on Thursday with drier conditions by Friday, as well as
warmer, yet still below climo temperatures.
Darmofal
.LONG TERM...(Saturday through Tuesday)
Issued at 322 PM CDT Tue Jun 29 2021
As the previous forecaster alluded to, the holiday weekend is
shaping up to be relatively pleasant with temperatures a bit below
seasonal climo and only small chances for showers and storms by
Monday. This will be thanks to a drier area of surface high
pressure settling across the Midwest thru Saturday on the back
side of the eastern conus upper trof. It is possible by Monday on
the observed holiday, that a subtle upper shortwave in the weak
northerly flow could affect the area resulting in slight precip
chances. Otherwise, Sunday the 4th looks dry.
KED
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 655 PM CDT Tue Jun 29 2021
Lots of low level moisture (tropical type airmass) continues to
linger across most of the area this evening, as pattern remains
stagnant. As the evening progresses, latest short range model
solutions suggest that low level moisture transport will linger
across the area at least until midnight, before waning for the early
morning hours on Wed. So expect widely scattered SHRA to linger for
the evening hours, mainly along and east of the KS Turnpike. Will
keep a VCSH in for most locations, for the evening hours.
Low level moisture transport isnt that impressive going into the
daytime hours on Wed, but latest short term model solutions suggest
the higher levels of moisture will linger over the area, with a
slight increase in instability for the afternoon hours on Wed. So
with an uncapped airmass expected for Wed afternoon, think scattered
to widely scattered SHRA and even a few TSRA will develop during max
heating on Wed. So will go with VCTS for the KICT and KCNU for Wed
afternoon.
MVFR and some IFR cigs will be likely under the showers, but
predominately MVFR cigs will prevail, except for central KS where
VFR are expected.
Ketcham
&&
.HYDROLOGY...
Issued at 322 PM CDT Tue Jun 29 2021
Showers with locally heavy rainfall will remain most numerous this
evening along the Kansas turnpike corridor with isolated heavy
rainfall across central Kansas. Later in the evening and overnight
showers are expected to become more numerous across southeast
Kansas once again, with scattered to numerous showers and storms
across south central and southeast Kansas on Wednesday. Additional
rainfall amounts in excess of 1.50" to 2" will be possible. If
this falls over recent over-saturated ground, then flooding will
be likely with rises on creeks and rivers as well.
KED
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 69 82 68 85 / 70 60 50 40
Hutchinson 68 83 66 85 / 40 50 40 30
Newton 68 82 67 85 / 70 60 40 40
ElDorado 68 82 68 84 / 70 70 50 40
Winfield-KWLD 69 82 69 84 / 70 70 60 50
Russell 65 85 64 86 / 20 30 30 30
Great Bend 66 84 66 85 / 30 40 30 30
Salina 68 84 66 86 / 40 40 30 30
McPherson 68 83 66 85 / 40 50 40 30
Coffeyville 70 83 69 85 / 70 70 70 70
Chanute 70 83 69 85 / 70 70 60 60
Iola 70 82 69 84 / 70 70 60 50
Parsons-KPPF 70 82 69 85 / 60 70 70 60
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Wednesday evening for KSZ052-053-068>072-083-
091>096-098>100.
&&
$$
UPDATE...Ketcham
SHORT TERM...KED
LONG TERM...KED
AVIATION...Ketcham
HYDROLOGY...KED
Area Forecast Discussion
National Weather Service Indianapolis IN
1143 PM EDT Tue Jun 29 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 930 PM EDT Tue Jun 29 2021
Diurnal convection continues to wane this evening. outflow boundary
now stretches from NW of Greensburg to to South of BMG...keeping the
bulk of ongoing diminishing storms in the SE part of the forecast
area. Elsewhere rain cooled air has allowed temps to fall into the
lower 80s...but dew point temps remain quite high in the lower 70s.
Looking at the bigger picture a plume of tropical moisture was still
in place over TX/NM streaming across the plains to the Ohio Valley.
This warm and humid air mass will continue to remain in place
tonight and into Thursday. HRRR suggests some convection developing
overnight...after 06Z perhaps triggered by a weak wave moving within
the tropical flow aloft. However radar and satellite upstream do not
clearly reveal this. Thus confidence is low. For now will trend
toward low pops for the next 6 hours as the outflow ushers ongoing
TSRA SE and out of the area and while diurnal heat loss continues.
Have trended pops back into the Chance category overnight due to the
development suggested by the HRRR.
Given the very high dew point temps...lows in the lower 70s appear
quite reasonable. Ongoing forecast on track here.
&&
.Short Term...(This evening through Wednesday night)
Issued at 258 PM EDT Tue Jun 29 2021
Another day of heat, humidity, and scattered convective development
across central Indiana today, with the bulk of thunderstorm
development currently ongoing along a weak prefrontal convergence
zone from southern Michigan back into central Illinois and central
Missouri.
Expect convective activity to continue to develop through the late
afternoon driven largely by diurnal processes and outflow boundary
interactions before weakening later this evening yet again. However,
as the broad upper level ridge weakens overnight, weak height falls
should overspread the area and the effective front may finally begin
to make progress toward the area. Subtle disturbances accompanying
the main upper level trough to the north may allow convection to
redevelop over the area late tonight and continue into Wednesday,
becoming more widespread during the day Wednesday and into Wednesday
night as the front moves into the area and the upper level trough is
finally able to sag into the area.
While the presence of the boundary and additional upper level
support will improve shear slightly, the improvement will be modest
at best, and continue to expect little more than a marginal severe
threat at any one time, with localized flooding the much more
significant threat as the profile will be quite moist with
precipitable water values approaching two inches.
The front and somewhat more widespread precip, along with lowered
heights, suggest cooler (if still oppressively humid) conditions
after today and tonight, and the blend handles this well.
&&
.Long Term...(Thursday through Tuesday)
Issued at 258 PM EDT Tue Jun 29 2021
Primary focus through the long term will be on the emergence of a
deep, upper level trough over the Mid-Atlantic, of which will result
in dry and sub-seasonal temperatures for the holiday weekend.
The continuous warm and humid surface conditions over the last week
will come to an end throughout the day on Thursday. This is
ultimately due to the amplification of the western CONUS ridge
altering the direction of CVA in a positively tilted trough;
Therefore creating a southerly push of pressure depression into the
eastern Great Lakes region. With deep low pressure to the east, the
overall flow will become predominately out of the north, advecting
much cooler and drier Canadian air into the western Ohio Valley.
Prior to its arrival, numerous showers are expected to develop along
a frontal zone, providing a high likelihood of rainfall for most of
central Indiana Thursday morning and afternoon. Rain chances will
diminish from north to south throughout the day, as the cP airmass
arrives. Thursday`s temperatures are likely to be curtailed by the
expected widespread cloud cover and rain, leaving afternoon
temperatures in the low 80s, but still with relatively high
humidity. Surface dew points will quickly drop following frontal
passage late on Thursday, with subsequent Friday morning lows
expected to be in the low 60s.
In the presence of strong CAA in the low to mid levels, pressure at
the surface is expected to slowly rise, resulting in a localized
area of higher pressure Friday and into the weekend. This will help
keep conditions dry and maintain the cool airmass for the entire
weekend. Expect highs in the upper 70s and low 80s Friday through
Sunday.
The pattern will begin to change once again early next week, as the
subsidence from the high weakens with its eastward progression. SW
flow in the wake of the high pressure departure will push higher
levels of moisture into central Indiana, with chances of rain next
Tuesday. Expect temperatures to return towards seasonal with early
next week as well.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1142 PM EDT Tue Jun 29 2021
IMPACTS:
* Mainly VFR conditions are expected this Taf Period.
* Isolated Thunderstorms producing MVFR conditions will be possible
after 300900Z.
DISCUSSION: HRRR suggests convective development across central
Indiana...but confidence in this is low with little in the way of
forcing available. Thus for now have included VCTS mention should
storms develop.
The tropical plume of moisture will remain in place over Indiana
through the Taf period...as upper forcing is expected to sag
southward into the plume along a weak cold front on Wednesday. This
should result in period of rain showers and storms on
Wednesday...starting by late morning. However confidence for precise
timing remains low. Mainly VFR Cigs will be expected but MVFR
conditions could be produced with any TSRA that strikes a TAF site.
Forecast soundings through the day remain saturated and favorable
for convective development.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...Nield
Long Term...Updike
Aviation...Puma
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1101 PM CDT Tue Jun 29 2021
.SHORT TERM... (Through Late Wednesday Night)
Issued at 248 PM CDT Tue Jun 29 2021
Scattered thunderstorms are forecast to continue late this afternoon
and evening. Locally heavy rainfall will remain the primary concern,
though isolated damaging wind gusts are also possible. Slightly
less deep-layer shear compared to yesterday suggests storms being
even more outflow dominant, effectively cutting off their own
updraft. In addition, the lack of steep midlevel lapse rates (near
5.0-5.5 C/km) suggests most storms will not be sufficiently tall
enough to produce either small hail or microbursts after they
weaken/collapse.
At least some waning in activity is anticipated this evening as
instability lessens nocturnally. Thereafter, precipitation trends
are difficult to discern as we move forward late tonight into
Wednesday. The latest 1200 UTC HREF paintball plots show a lot of
spread in the more focused activity, but the general agreement is
for convection to orient itself more west to east as mid/upper level
ridging weakens and slides east. A shortwave trough is expected to
move across the Mississippi River Valley on Wednesday helping to
provide forcing for ascent, but the magnitude and track of this
feature varies considerably amongst CAMs and global guidance. The
extended 12Z HRRR suggests the possibility even of an MCV from late
tonight`s activity being a focusing mechanism to re-generate
thunderstorms heading into the afternoon.
There likely will be a bit of a lull behind the departing shortwave
trough/MCV Wednesday evening. However, a seasonably strong cold
front is forecast to move into the CWA Wednesday night ahead of an
amplifying longwave trough. Strong synoptic forcing for ascent aided
by the aforementioned trough and divergence beneath a jet streak
over the Great Lakes should lead to widespread showers and
thunderstorms with the frontal passage. Most of this activity should
occur late Wednesday night into Thursday morning from east-central
and southeast Missouri into southwest Illinois. Assuming this does
indeed occur, the rain would occur in many areas that have not
received too much rain over the past week. Portions of southeast
Missouri and southwest Illinois in fact have had little to no
precipitation so this rain would be very beneficial.
Gosselin
.LONG TERM... (Thursday through Next Tuesday)
Issued at 248 PM CDT Tue Jun 29 2021
The well-advertised pattern change is still on schedule for later
this week into the weekend. The strong cold front bringing another
round of showers and thunderstorms should exit the area on Thursday.
Behind this front, much cooler and drier (less humid) air will
infiltrate the mid-Mississippi Valley. The air mass looks fairly
impressive for early July, with 850-hPa temperatures dropping to
near +10C or nearing 2 sigma below normal. High temperatures are
forecast to be in the upper 70s to low 80s on Friday and Saturday,
with lows Friday and Saturday night below 60 degrees in most
locations. These values would be about 10 degrees below normal.
Some moderation in temperatures is favored beginning Sunday into
early next week, but there is quite a bit of uncertainty with
specifics. Cluster analysis of the 500-hPa height pattern shows a
large spread in the strength of the mid/upper level trough moving
out of the Great Lakes in this time frame, and the progress eastward
of the upstream ridge axis. The deterministic ECMWF and EPS mean
remain on the cooler side compared to the GFS/GEFS mean. Regardless,
dry weather remains favored through Monday with temperatures warming
back to at least closer to normal by Monday. Therefore, the holiday
weekend all things considered looks to be quite comfortable with
seasonably cool temperatures, low humidity, and little/no chance of
thunderstorms.
Gosselin
&&
.AVIATION... (For the 06z TAFs through 06z Wednesday Night)
Issued at 1051 PM CDT Tue Jun 29 2021
For KUIN/KCOU/KJEF: After a lull in precipitation this evening
there should be a gradual uptick in the coverage of scattered
showers overnight. I think for the most part that if these impact
the terminals, flight conditions will still remain VFR. The
coverage of showers and storms will increase on Wednesday morning
with showers and storms periodically impacting the terminals
through the day. Flight conditions with the greater periods of
precipitation should lower to at least MVFR.
For the St. Louis metro terminals: Present indications are
precipitation should largely remain north and west of the
terminals overnight. I have retained the TEMPO group for a
potential for a period of MVFR fog overnight at KSUS and KCPS. I
am still thinking the cloud cover will inhibit significant fog.
Scattered showers and storms should ramp up again on Wednesday
afternoon, especially mid-late afternoon, impacting the terminals
at times into the early evening.
Glass
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
916 PM CDT Tue Jun 29 2021
.UPDATE...
Showers had dissipated over the Midsouth early this evening.
Several CAMs depict additional scattered showers forming
over north MS into southwest TN overnight, in association with an
inverted midlevel trof. Current forecast has this scenario
covered well.
PWB
&&
.PREV DISCUSSION... /issued 625 PM CDT Tue Jun 29 2021/
UPDATE...
Updated for the 00Z Aviation Discussion
PREV DISCUSSION... /issued 304 PM CDT Tue Jun 29 2021/
DISCUSSION...
The remnants of Tropical Storm Danny continue to move west across
the West Tennessee and Northeast Mississippi at this time. Looks
like the line may hold together to reach the Memphis Metro in the
next 2-3 hours. Still uncertain as how far west it will go. The
HRRR continues to struggle with what is occurring now. The 12Z
NSSL-WRF, which had the best handle, had it dissipating once it
got to the Mississippi River, thus based evening POPS on this
scenario. However, would not be surprised to see it move further
west.
Leftover boundaries from the convection will be the trigger point
for convection during the overnight hours into the morning hours
on Wednesday. By the afternoon, scattered convection could just
occur about anywhere in the CWA. Coverage should diminish after
sunset due from the loss of daytime heating.
Better chances for showers and thunderstorms will occur on
Thursday into Friday as a cold front drops south from Missouri
into the Mid-South. Any of the storms will have the potential to
become strong or possibly severe from this afternoon through the
frontal passage on Friday. Gusty winds and locally heavy rainfall
being the main threats.
Beautiful weather is expected for the Independence Day holiday as
cooler and drier air filters into the region behind the front.
Highs will be in the 80s with low humidity.
Forecast confidence dwindles by early next week as models diverge
on solutions. The GFS and Canadian builds an upper ridge over the
area bringing hot and humid conditions back to the area. However,
the ECMWF has a weak disturbance getting stuck within the ridge
which could bring rain chances to the Mid-South. Stay tuned.
KRM
&&
.AVIATION...
00Z TAF cycle
VFR conditions should continue through the entire forecast period.
The thunderstorm activity that moved into the region earlier today
is rapidly diminishing. Another round of thunderstorms is expected
to move into northeast sections of the Mid-South Wednesday morning
and spread across the remainder of the region in the afternoon.
Winds will be mainly from the south at 5 to 10 knots for much of
the forecast period.
ARS
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 329 PM CDT Tue Jun 29 2021
...Today & Tonight...
500 hPa RAP analysis continues to show the axis of a positively
tilted trough extending from the central high plains into the Great
Lakes region. This in conjunction with subtle convergence along a
weakening stationary front will provide sufficient support for
isolated to widely scattered convection across southeast Nebraska
and southwest Iowa through the evening hours. This activity is
expected to be confined to the I-80 corridor and south. Drier
weather is expected north of I-80 as convergence aloft and strong
mid-level subsidence will act to suppress any possible convection.
Calm winds, and RH values near or at 100% across much of
southeast Nebraska and southwest Iowa will bring the possibility of
patchy fog for tonight. This is expected to impact locations along
and south of US-30. Variable upper level clouds, however, should
mitigate the risk of widespread dense fog across the region.
Nonetheless, any areas that can see a clearing in upper level
clouds, particularly in the Missouri river valley south of the Omaha
metro and in parts of southwest Iowa, will have the possibility
of seeing isolated patches of dense fog with visibilities as low
as a 1/4 of a mile. Fog is expected to start developing after
midnight with some places seeing fog remain until an hour or two
after sunrise.
...Tomorrow through next Tuesday...
Tomorrow afternoon, a remnant shower or thunderstorm is possible
in far southeast Nebraska/southwest Iowa as the upper level trough
currently over our region deamplifies and propagates to the
northeast. Dry weather and seasonal temperatures are expected to
prevail across our region Thursday and into the weekend as a
longwave ridge builds in from the northwest. By the beginning of
next week, medium range guidance is suggesting a flattening of the
ridge over the central CONUS with subtle shortwave troughs ejecting
into the central and northern Plains. This in conjunction with
moisture return from the Gulf will increase our rain chances by the
end of the forecast period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 642 PM CDT Tue Jun 29 2021
Isolated showers will persist across the KOMA for the first few
hours of this TAF cycle. Although they have produced little to no
lightning, we have received a handful of funnel cloud reports. If
funnels do form with these showers, it is very unlikely that they
would be able to reach the ground. Otherwise, patchy fog will be
possible across KOMA and perhaps KLNK early Wednesday morning,
followed by continued light winds and VFR conditions.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Mead
AVIATION...KG
Area Forecast Discussion
National Weather Service Pendleton OR
902 PM PDT Tue Jun 29 2021
.UPDATE...The strong upper high pressure system that brought the
very hot temperatures to the region is weakening and beginning to
move off to the northeast. In the mean time, a low pressure system
along the coast will spread mid level moisture northeast into the
forecast area beginning on Wednesday afternoon and evening. This
combined with the continued hot (through not as hot) temperatures
will create enough instability for isolated late afternoon/evening
thunderstorms to develop from central OR northeast to the Wallowa
and Elkhorn mountains, and the John Day Highlands. Most areas will
just have some afternoon cumulus development with some buildups.
Then on Thursday, the flow aloft will become more southwesterly
and will pull more mid level moisture and instability into the
forecast area, resulting in a better chance of afternoon and
evening thunderstorms on Thursday, again from central OR to the
northeast Mountains, and also with greater coverage. Temperatures
on Thursday will be cooler than Wednesday with increasing
humidity, especially from central OR to the northeast mountains.
Winds will shift and become mostly westerly beginning Wednesday
and continuing into Thursday as a thermal surface low moves to the
east. Though they will be cooler, temperatures will still be well
above normal...and in the 100s in the lower elevations, with 80s
and 90s in the mountains through the remainder of the week and
through the weekend. The Excessive Heat Warning will remain in
effect until 8 PM Sunday as a result. 88
&&
.AVIATION...06Z TAFs...VFR conditions will prevail during the
next 24 hours. There will be some cumulus development in the
afternoon at all terminals on Wednesday. These cumulus could
develop into an isolated thunderstorm or two just south of KBDN in
the evening Wednesday. Winds will shift to the west to northwest
at all terminals with speeds of mostly 10 to 20 kts with possible
gusts to 30 kts at times, especially at KDLS, KBDN, KRDM and
KYKM. 88
&&
.PREV DISCUSSION... /issued 507 PM PDT Tue Jun 29 2021/
Updated aviation discussion
SHORT TERM...Tonight through Thursday night...Record breaking
temperatures have already been observed, including all time records
at the Yakima Airport and the Pendleton Airport. Excessive Heat
Warnings remain in effect through Sunday. It`s possible that the
warnings could be downgraded to advisories in some of the zones
later in the week as heat risk graphics show less concerns compared
to the dangerous heat conditions today. Will keep the warning going
for now. Weather concerns are focusing on the fire weather issues
starting tomorrow. As high pressure shifts eastward and weakens
over the region, instability will increase. A closed low with
moisture dissipating around its periphery is traveling north off the
Oregon coast and forcing the high pressure ridge eastward. The
inverted surface thermal trough is also shifting eastward, and the
onshore flow will strengthen overnight and Wednesday. Winds will
increase tonight through the Columbia River Gorge tonight and will
have winds around 15-20 mph gusting to 30 mph by mid day Wednesday.
Later in the afternoon winds will increase along the I84 corridor as
far east as Boardman but also over north central Oregon and the
Simcoe Highlands. Winds may decrease briefly Wednesday night but
increase again on Thursday where a tight cross Cascade gradient will
be present. Looking at the Hot-Dry-Windy Index, the conditions are
not extreme but still high to warrant Red Flag Warnings.
Isolated to scattered thunderstorms are expected Wednesday
afternoon/evening and again on Thursday. The upper level flow over
the southern half of Oregon will become more southerly, albeit weak.
Diurnally driven thunderstorms will develop over the southeast
zones, and the LALs of 2-3 will pose concerns for new fire starts.
The air mass is very dry, therefore storms will likely bring very
light rain or virga. The HREF would support this, although a
couple of members of the HREF seems a bit overdone on areal
coverage late Wednesday. Moisture will deepen with PWATs around 1
inch by Thursday. The potential for thunderstorms is greater on
Thursday, and mainly in the eastern mountains and valleys. But,
the steering flow should be weak with better chances for wetting
rain with most storms.
The smoke from the Lava Fire near Mt. Shasta is currently confined
to southwest Oregon, but smoke aloft may make its way to central
Oregon by Thursday as the flow increases from the south. The HRRR
vertically integrated smoke would show more smoke aloft than at the
surface. Will keep an eye on the Lava Fire or any other new fires
to determine if smoke is needed for the forecast. Wister
LONG TERM...Friday through Tuesday...Heading into the holiday
weekend, temperatures will start to tick downward a bit as the axis
of the strong overhead ridge moves eastward, however high pressure
will continue to linger. High temps across the area are expected to
remain 10-15 degrees above average through at least early next work
week, with highs at or near triple digits for most areas. On top of
hot conditions, an offshore trough forming off the coast of
California will usher in some weak SW flow over central OR through
the Blues, introducing a chance for thunderstorms Friday, with a
lesser chance Saturday.
Sunday onward, ensembles a bit split on depicting the synoptic
pattern, with some members showing some zonal flow over the PacNW,
which would offer stronger relief from the hot temperatures, while
other members produce a weak offshore trough heading into the
midweek, which would create elevated fire weather concerns with
possible t-storms and breezy conditions. Ensembles, however, leaning
towards some kind of respite from triple-digit heat beyond the
Fourth of July, with most areas possibly seeing a return to near
normal highs in the low to mid 90s across the Basin and central OR.
74
FIRE WEATHER...Red Flag Warnings were issued for the Lower
Columbia Basin south of the Tri-Cities down towards Condon and
just north of Warm Springs for wind and low humidity from
Wednesday through Thursday evening. In addition, Fire Weather
Watches were issued for the John Day Basin and surrounding
mountains, the southern Blue Mountains, and Wallowa County for
thunderstorms producing abundant lightning. Both the wind/RH
threat and the thunderstorm threat were not slam dunk decisions.
The conditions will meet low end red flag criteria, but the latest
heat wave poses major concerns for fire spread and fire behavior.
Not only will winds be a concern, but the instability. Wister
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 76 107 69 100 / 0 0 0 0
ALW 80 110 74 103 / 0 0 0 0
PSC 78 112 75 105 / 0 0 0 0
YKM 77 108 71 102 / 0 0 0 0
HRI 78 110 72 104 / 0 0 0 0
ELN 72 103 68 97 / 0 0 0 0
RDM 64 101 59 98 / 0 0 10 0
LGD 73 103 68 99 / 0 0 20 20
GCD 74 106 67 100 / 0 10 20 20
DLS 74 99 70 96 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 8 PM PDT Sunday for ORZ041-044-049-
050-502-503-505>511.
Red Flag Warning from 11 AM Wednesday to 10 PM PDT Thursday for
ORZ639-641.
Fire Weather Watch from Wednesday afternoon through Thursday
evening for ORZ642-644-645.
WA...Excessive Heat Warning until 8 PM PDT Sunday for WAZ024-026>030-
520-521.
Red Flag Warning from 11 AM Wednesday to 10 PM PDT Thursday for
WAZ639-641.
&&
$$
SHORT TERM...88
LONG TERM....74
AVIATION...88
Area Forecast Discussion
National Weather Service Phoenix AZ
427 PM MST Tue Jun 29 2021
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
Scattered showers and thunderstorms will be common around the region
throughout the week as monsoon moisture steadily increases. Strong
winds and localized blowing dust will be the main impacts for most
lower desert communities. However, a transition to a heavier
rainfall threat may materialize during the latter half of the week,
particularly for wildfire burn areas. Temperature should hover
slightly below normal coincident with the moisture increase.
Thunderstorm activity may wane somewhat early next week while
temperatures increase as the monsoon pattern temporarily realigns.
&&
.DISCUSSION
Latest water vapor imagery and RAP streamline analysis clearly
trace out the flow around a well-defined inverted trough across
southern NM. This is resulting in stronger than normal northerly
winds across Arizona. Within this stronger mid-level speed max, a
complex of showers and thunderstorms developed this morning across
NW Arizona in an area characterized by steep mid-level lapse
rates and colder air aloft. Some of this activity drifted into
northern Maricopa County this afternoon, but subsequently fizzled
out.
Hi-Res CAMs including the HREF have struggled so far today and
generally failed to initialize the placement of the morning
convection. During situations like this, it is generally prudent
to rely more on the HRRR, which has captured the storms currently
along the Mogollon Rim. Latest ACARS from Phoenix indicates PWATs
have increased to near 1.2 inches. Combined with cooler air aloft,
this is yielding MLCAPE between 500 and 1000 J/kg. CIN is only
negligible, which will promote at least isolated thunderstorm
development later today, assuming an outflow boundary from the
aforementioned Rim convection reaches the Valley.
Did not deviate much from the NBM PoP for tonight, which
indicates a widespread 30 percent. Mesoanalysis indicates DCAPE
around 1500 J/kg and consequently, the strongest storms will be
capable of producing wind gusts to 50 mph, and areas of blowing
dust.
&&
.PREVIOUS DISCUSSION...
Outflows, Gulf surges, and the outer influences of Enrique should
begin a marked increase in total column moisture content Wednesday
with forecast soundings indicating 11-12 g/kg mixing ratios in the
lower levels. Still, a persistent dry northerly flow towards the top
of the boundary layer may continue to create a negative influence on
realizing full convective potential at lower elevations. The
moistening will also result in reduced lapse rates and lower overall
instability measures while the inhibition remains. Favorable ascent
will still be present juxtaposed with sufficient DCape to create
another day of multiple outflow boundaries. Given better moisture
profiles and modestly weaker inhibition, convection may be most
expansive Wednesday evening versus other days this week with a flood
threat added to the wind and dust threat. CAMs still do not present
a resounding indication or better confidence of more extensive
storms and forecast soundings don`t depict the telltale signs of
convective overturning suggesting more isold/sct coverage.
The Conus pattern will undergo an adjustment period towards the end
of the week with the strong northern ridging shifting eastward into
the northern plains. During this transition, the inverted trough
along the international border will eject into the East Pacific
while subtropical Gulf of Mexico ridging retrogrades into the
Southwest. The local flow pattern will gradually become more
subsident incorporating some drier westerly winds aloft early next
week. However, lingering moisture will allow terrain forced storms
to percolate most days though the trend will be towards less chance
of maintenance into lower deserts with time. Conceivably, there
could be a certain day with a better defined shortwave or jet streak
to enhance lift and allow storms to persist across a greater
majority of the CWA. Pinpointing any specific day this far in
advance is impossible and POPs mostly resolve back towards a
climatology type forecast by the end of the forecast period.
&&
.AVIATION...Updated at 2330Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
There are uncertainties regarding winds and thunderstorms the
next few hours. While westerly winds have become predominate at
all TAF sites, there is a northerly/northeasterly outflow boundary
moving towards the area. Timing the arrival and potential wind
strength is unclear but the most certain outcome of this boundary
is for a northeasterly wind switch at KSDL and KDVT within the
next hour or so. If speeds are weak, the boundary may wash out
over the metro and not impact any other sites, allowing the
westerly winds to continue. If the boundary is strong, between
15-25 kts, or is reinforced by new convection, expect the boundary
to propagate through all TAF sites between 01/02Z. For later this
evening, if convection forms due east, there could be additional
outflows from that direction. The chances for convection within
the general area is between 30-50% favoring the higher terrain
east of Phoenix, with lower chances (10-15%) for storms over any
given terminal. Easterly winds will prevail through the night with
a few hours of a westerly wind anticipated again tomorrow afternoon.
If trends for isolated convection today continue, conditions for
more widespread thunderstorms may become more ripe Wednesday
afternoon and evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
Southerly to southeasterly winds are anticipated at both sites with
speeds primarily between 8-12 kts. However, there is a low chance
(10-15%) that distant convection could send outflows through the
area, either from the north and/or south, late tonight. Conditions
seem too dry for any storms in the area but occasional dense cloud
cover may pass overhead.
&&
.FIRE WEATHER...
Friday through Tuesday:
Thunderstorms with gusty, erratic winds and localized heavy rainfall
will be common over eastern districts through the weekend with lower
chances in western districts. On most afternoons, there will be at
least a 50% chance of storms with similar chances of wetting rains.
The threat for flash flooding on already burned area will also
exist. Moisture levels will peak during the middle and end of the
week with minimum afternoon humidity values mostly in a 20-40% range
and good overnight recovery in a 30-60% range. Somewhat drier
conditions will return early next week with storm chances lowering,
albeit still present each afternoon over higher terrain of eastern
districts. Aside from the influence of thunderstorms, winds will
follow the typical upslope/drainage diurnal trends.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...MO
AVIATION...AD
FIRE WEATHER...MO/Hirsch
Area Forecast Discussion
National Weather Service Shreveport LA
937 PM CDT Tue Jun 29 2021
.UPDATE...
Overall, the afternoon forecast package still holds valid, and
required only minor adjustments. Increased PoPs to ~20% in our
southern zones from 03-06Z to reflect lingering rainfall across
the area. Beyond 06Z, the dryer pattern indicated in the latest
RAP and HRRR runs looks to hold true through the afternoon
Wednesday. Otherwise, updated temperature grids with the latest
obs and interpolated through the overnight hours to the forecast
morning lows. /26/
&&
.PREV DISCUSSION... /issued 634 PM CDT Tue Jun 29 2021/
AVIATION...
For the 30/00z TAFs, scattered showers and thunderstorms are
expected to continue through the evening, particularly across our
East Texas sites and possibly at KSHV. However, can`t rule out
some isolated convection at our remaining sites. Continued to
Tempo in convection at TYR/GGG/SHV. This convective activity is
expected to start to diminish after sunset, after which VFR
conditions will prevail. However, lower ceilings and slightly
reduced visibilities are expected around 30/12Z, especially in
regions which see precip this evening. VFR conditions will then
return Wednesday afternoon. /26/
PREV DISCUSSION... /issued 256 PM CDT Tue Jun 29 2021/
SHORT TERM.../Tonight through Wednesday Night/
An upper ridge continues to expand westward from the Mid Atlantic
region into the Mid South, and into portions of the Lower
Mississippi Valley. At the same time, low level gulf moisture
continues to stream northward into the region this afternoon on
the backside of an easterly wave along the Gulf Coast near the
Alabama/Florida coastline. Isolated to scattered convection is
on-going across the region this afternoon and will likely expand
in coverage over the next several hours with daytime heating.
Models continue to suggest that greatest coverage will be west of
the I-49 corridor, especially across our East Texas zones, as the
upper ridge should limit coverage across the eastern 2/3rds of
the region. Locally heavy rain and gusty winds will be possible in
the stronger storms, but no widespread severe weather is expected.
Most of this activity should diminish after sunset with the loss
of daytime heating. Lows overnight will drop down into the lower
70s, with some low cigs and patchy fog possible close to daybreak.
On tomorrow, the ridge will continue to build westward across the
Lower Mississippi Valley into the Southern Plains. This will
limit our rain chances, but there should be enough lingering low-
level moisture and diurnal instability for some isolated showers
and thunderstorms during the afternoon hours. However, with less
rain across the region, afternoon temps will likely climb into the
lower 90s areawide. Like today, most of the convection will
diminish by sunset. But, additional rain could develop late
Wednesday night in areas north of the Interstate 30 corridor ahead
of a weak cold front diving down the Plains. /20/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 73 93 75 94 / 20 20 0 30
MLU 72 92 74 94 / 10 20 10 40
DEQ 72 90 73 88 / 20 30 10 60
TXK 74 91 75 91 / 20 20 10 50
ELD 71 92 73 92 / 10 20 10 40
TYR 72 90 74 92 / 30 20 0 30
GGG 72 90 73 91 / 30 20 0 30
LFK 72 90 73 93 / 30 20 10 30
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
26/26/20
Area Forecast Discussion...UPDATED
National Weather Service San Angelo TX
658 PM CDT Tue Jun 29 2021
...New AVIATION...
.SHORT TERM...
(This evening through Wednesday)
Issued at 229 PM CDT Tue Jun 29 2021
Scattered showers and storms that develop this afternoon will
continue into the evening hours. They are expected to taper off not
too long after sunset. An upper level ridge is starting to build
back into the area which will increase subsidence and hurt chances
for storm persistence. Lows tonight will be in the upper 60s to low
70s with winds continuing out of the southeast at generally less
than 10 knots.
There`s a little bit of difference between the hi-res models on the
amount of shower and storm activity for tomorrow. They all show a
substantial decrease in activity compared to the past two days due
to the increase in subsidence from the aforementioned upper level
ridge. The NAM Nest shows little to nothing in the way of activity
with it`s thinking that the subsidence from the ridge will outpace
any lift over the area. The HRRR on the other hand shows a modest
amount of widely scattered showers and storms across the area. If
showers and storms do form, it will be a similar story to the past
few days. HRRR soundings show long skinny CAPE profiles with MLCAPE
values ranging from 500-1500 J/kg and SBCAPE values ranging from
1000-2000 J/kg across the area (likely due to breaks in the clouds
and subsequent surface heating). There will also be virtually no CIN
to prevent development. There will still be ample moisture across
the area with surface dewpoints in the upper 60s to low 70s and
continued south to southeasterly flow bringing in that rich gulf
moisture. HRRR soundings continue to show a very saturated profile
with PWat values ranging from 1.75-2 inches. This high water content
in conjunction with, once again, very little shear will allow for
slow moving showers and storms that could quickly drop a lot of
rain. Heavy rainfall and flooding in already saturated areas will be
the main threats.
&&
.LONG TERM...
(Wednesday night through next Tuesday)
Issued at 229 PM CDT Tue Jun 29 2021
Looks like West Central Texas will remain in an unsettled pattern
through the long term, with a few periods of showers and
thunderstorms. Looks like Thursday through Friday will be mainly
isolated showers and thunderstorms during the afternoon and
evening. However, Thursday looks to be mainly dry as a flat upper
level ridge builds across the area from east to west. Rain
chances increase this weekend as a weak cold front moves south
into west central Texas and abundant tropical moisture will be
over the area. The main impacts will be heavy rainfall and
potential localized flooding. The NBM Pops were reduced some due
no significant lift and only surface heating. Will keep chance
Pops going into early next week. The warmest days will be Thursday
and Friday with highs in the upper 80s to lower 90s, then cooling
off over this weekend, including the 4th of July. Also, expect
humid weather during the long term.
&&
.AVIATION...
(00Z TAFS)
Issued at 642 PM CDT Tue Jun 29 2021
Widely scattered showers and a few thunderstorms are occurring
early this evening across West Central Texas. Carrying VCTS at
our TAF sites at the start of this TAF package (00Z-03Z). This
convective activitiy is expected to dissipate early tonight, by
or shortly after 03Z. Brief reductions in visibilities and
ceilings are possible in locally heavy rain accompanying the
convection. Erratic winds with gusts 30-35 knots are also
possible. Outside of the convective activity, VFR conditions and
partly cloudy skies early tonight will give way to low cloud
development/ expansion overnight with MVFR ceilings. Considerable
low cloud coverage with MVFR ceilings is expected in the early to
mid-morning hours Wednesday. Anticipate that ceilings will persist
into the afternoon, but ceilings should climb above 3000 ft by 16Z.
Widely scattered showers and thunderstorms are possible on Wednesday
afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 69 86 70 88 / 40 30 5 20
San Angelo 69 88 69 91 / 40 30 10 20
Junction 69 88 69 91 / 30 40 10 20
Brownwood 70 88 71 91 / 30 30 5 20
Sweetwater 69 84 69 86 / 40 30 5 20
Ozona 69 85 69 88 / 40 40 20 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...50
LONG TERM....21
AVIATION...19