Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/01/21

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 806 PM MDT Wed Jun 30 2021

.UPDATE...
Issued at 752 PM MDT Wed Jun 30 2021

N/S oriented boundary moving west of US 85 toward I-25, with a
surface cyclonic circulation just west of DIA. Boundary along with
surface based CAPE 500-1000 j/kg along the I-25 corridor & along
the Palmer divide this evening supporting widely scattered
convection. Persistent slow moving cluster of thunderstorms in
northwest Weld county, and raised pops in that area for a few more
hours. Other showers in the vicinity of KDEN popping up and
dissipating, not even making thunder. Lowered pops through
midnight northeast plains where nothing is going on yet. HRRR
remains bullish on bringing showers out of the foothills and along
Palmer Divide, and left chances down there overnight spreading
onto the eastern plains after midnight. Tweaked the POPs with this
update, blended in current temperatures, and left the overnight
lows alone.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 240 PM MDT Wed Jun 30 2021

Scattered showers and thunderstorms have begun to form across the
higher mountains and east slopes early this afternoon. So far,
instability is marginal with CAPE VALUES 400-800J/KG while  storm
motions around 10kt. There has been just enough motion to keeping
storms moving to prevent any major flooding across higher
terrain. Across lower elevations, outflow boundaries may spark
storms later this afternoon and evening which most models are
picking on best focus for storms east and south of Denver and
across Palmer Divide. Confidence is low on how far east the
convection develops this evening, but certainly coverage more
isolated out on the plains. The 50kt jet streak across southeast
Colorado does slowly sag further south and east but still may have
some interaction in shower development overnight and will keep in
some low pops. The southeast low level flow also appears to drag
in additional moisture from Kansas. Will also have chances of
showers across the plains in the morning as well.

The main concern for Thursday is a higher threat of flash flooding
across the burn scars and adjacent areas in the mountains and
adjacent plains. The weak upper trof remains across Utah with a
continued light southwest flow aloft over Colorado. There is a
definite upswing of moisture across the area with precipitable
water values up over an inch across all the plains. The model
forecast instability increases with SFC based CAPES increasing
upwards of 1500j/kg. However with increased cloud cover,
wondering if will come up a bit short and actual CAPES remaining
under 1000j/kg. It also appears storm motions may end up being
similar to today with 10kt storm motion from the west and
southwest. The latest HRRR reflectivity of storms has actually
surprisingly decent storm motions which would reduce the flash
flood threat. Regardless, the threat will be higher on Thursday
afternoon then today, but confidence not high enough to issue a
flash flood watch. Temperatures will be a bit cooler with more
cloud cover than today. Will still go with likely pops in most
areas Thursday afternoon given the moisture uptick, so overall not
many changes in forecast.

.LONG TERM...(Thursday night through Wednesday)
Issued at 240 PM MDT Wed Jun 30 2021

Isolated areas of heavy rainfall will likely continue into the
early overnight hours Thursday night. Activity should decrease
fairly quickly after sunset surface stability increases, with just
a few overnight showers after midnight.

Friday`s pattern is largely the same as Thursday, with a few
subtle differences. Temperatures are likely to be just a little
warmer, with surface dew points a couple degrees drier. GFS/ECM
both suggest that CAPE across the area will be almost identical to
Thursday. Forecast soundings show mean-cloud layer flow of about
10kt during the afternoon, with a fairly shallow warm cloud layer.
Still, the current thought is that heavy rainfall will continue
to be a concern over most of the high country. PWATs will still be
near an inch across the Foothills and near 3/4 of an inch west of
the divide. Guidance does try to keep the convective focus across
our higher terrain unlike Thursday, and the primary concern for
the day will be for burn area flash flooding.

The pattern does slowly get warmer and drier this weekend, with
chances for afternoon thunderstorms both Saturday and Sunday. The
flow aloft does strengthen a touch both days, which should lead to
slightly faster storm motions, but there will likely be some
flash flooding concerns again over our burn areas. Highs across
the plains will reach the upper 80s to low 90s. Monday will
perhaps be the driest day of the week, with scattered storms for
the mountains and an isolated storm or two along I-25. A shortwave
should bring a push of slightly cooler air and increased
thunderstorm coverage, with more uncertainty Wednesday and beyond.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 543 PM MDT Wed Jun 30 2021

VFR, with scattered showers and maybe a rumble of thunder this
evening. We left VCTS in for Denver through 02z in lingering
instability and colliding outflow boundaries, then VCSH for a few
more hours. Hi resolution models showing a band of convection
moving out of the foothills and through the TAF sites 03-05z so
left VCSH through then. Boundary/Denver Convergence Zone has set
up NNE/SSW oriented, just west of KDEN and KAPA and just east of
KBJC. Forecast it to remain stationary through the evening. Toward
morning a Denver Cyclone will set up again, but details on where
are elusive. For the TAF went with HRRR model solution, with SSW
wind becoming east in the afternoon, then Thursday afternoon
convection after 20z.


&&

.HYDROLOGY...
Issued at 240 PM MDT Wed Jun 30 2021

Thunderstorms so far have been on the weaker side in the mountains
this afternoon given the marginal instability while storm motions
are moving storms enough to limit the threat for flooding. There
will be an increasing threat of flash flooding over the burn scars
on Thursday afternoon with higher moisture levels. However storm
motions again maybe quick enough to prevent any major flooding.
For now confidence too low to issue a flash flood watch.

Elevated flash flooding threat will continue on Friday with slow
moving thunderstorms likely again across the burn areas. There is
some uncertainty regarding the amount of moisture and instability
available Friday afternoon, but conditions will generally be
similar to Thursday. The flash flooding threat should decrease
through the weekend as the pattern gradually turns warmer and
drier, but heavy rainfall will still be possible each day with
scattered thunderstorms likely.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...Hanson
SHORT TERM...Entrekin
LONG TERM...Hiris
AVIATION...Hanson
HYDROLOGY...Entrekin/Hiris



Area Forecast Discussion

National Weather Service Louisville KY

 844 PM EDT Wed Jun 30 2021

.Forecast Update...
Issued at 840 PM EDT Wed Jun 30 2021

Radar continues to show isolated convection across our CWA this
evening. Brief heavy downpours and wind gust of near 25 mph seem to
be the main impacts from these cells. Expect more of the same as we
go through the rest of the evening and into the first half of the
overnight. Few clusters of rain/storms have been trying to work out
of far southwestern Indiana into our CWA but have weakened as they
move eastward, and with the loss of daytime heating expect more
weakening to occur. Hi-res models haven`t initialized well with much
of the ongoing convection this evening but continue to advertised a
brief lull in activity until about 06z to 07z. Have adjusted our PoP
grids to reflect this lull and isolated nature of convection.

As the upper level trough pushes southward overnight, expect
possible redevelopment of shower and possible storms between 06z-12z
in southern Indiana and northern Kentucky. Forecast soundings
continues to maintain SBCAPE values around 2000 J/kg as well as a
nice saturated column, so some thunder is possible with any
activity. Heavy rain will also be an issues as PWAT values remain
near 2.00" and dew points in the low/mid 70s. Localized flooding
would be the main concern from any early morning showers and storms,
especially for the morning commute along the I-64 corridor. No other
changes have been made to the forecast grids.

&&

.Short Term...(This evening through Thursday)
Issued at 315 PM EDT Wed Jun 30 2021

KLVX began showing pop up showers initiate along the I-64 corridor
around 18z. SPC Mesoanalysis reveals MLCAPE of 1500-2000 J/kg and
steep low level lapse rates of 7.5C/km in a very moist airmass with
PWATs greater than 1.9". Sfc temperatures have remained in the mid
80s under an increased mix of clouds. Despite temps staying below
90F, dewpoints have remained in the low 70s, making for quite a
muggy day across the region. Expect to see showers and storms
continue this afternoon and evening, primarily across southern IN
and north central KY as the sfc cold front currently stretching
across northern IL/IN continues to sag southward tonight and
interacts with our moist airmass.

Upper level shortwave will be digging southward overnight helping to
push the slow moving sfc boundary further south and provide
additional lift to our region. Hi-res guidance suggests a brief lull
in precip activity this evening, but renewed development looks to
take place late tonight or during the overnight hours, focused over
southern IN and expected to spread southward through the region as
the front approaches. RAP soundings suggest we`ll hold on to sfc
based instability tonight and a saturated column, so expect to have
at least some thunder mixed in with numerous showers. Weak flow
aloft will help limit any recognizable shear, so no severe wx is
expected.

By tomorrow morning, widespread showers and storms are expected
across the region within a continued moist environment. CAPE values
will be meager with overcast skies, so continue to think storms will
remain sub-severe for tomorrow. Precip chances continue into the
afternoon hours. Main hazards will be intense rainfall rates and
slow storm motions, leading to localized flooding concerns. OHRFC 1
hour FFG is around 2 inches, and 3 and 6 hour FFG is roughly 3-4
inches. Think we`ll have a chance of meeting or exceeding the 1 or 3
hour FFG with a slow moving storm that puts down impressive rainfall
rates.

Temperatures for tomorrow will remain in the upper 70s to near 80F,
but should be another muggy day with dewpoints once again around 70.

.Long Term...(Thursday night through Wednesday)
Issued at 230 PM EDT Wed Jun 30 2021

As we head into Thursday night, expect showers and storms to taper
off from northwest to southeast as the surface cold front finally
pushes through the area. With the upper trough and cold front
exiting off to the east by Friday, we will transition to a drier and
somewhat cooler pattern as surface high pressure along with ridging
aloft begin to build over the area. Under northerly flow behind the
front, low temperatures Thursday night into Friday morning will
generally be in the lower to mid 60s. Low temperatures will then
trend even cooler as we head into the weekend, with overnight lows
in the mid 50s to lower 60s. High temperatures are also expected to
remain below climatological normals Friday and Saturday, topping out
in the upper 70s to lower 80s.

By the start of next week, the upper pattern will begin to flatten
out a bit while southerly flow starts to take hold in the lower
levels as high pressure drifts to the east. This will result in
temperatures warming near/slightly above normals once again with
highs in the upper 80s to lower 90s through the end of the period
and overnight lows in the upper 60s to lower 70s. May begin to see
some diurnally driven precip chances in the afternoon and evening
hours next week; however, will maintain just slight chance PoPs at
this time with lower confidence in any finer details.

&&

.Aviation...(00Z TAF Issuance)
Issued at 715 PM EDT Wed Jun 30 2021

Main concern this evening is impact of convection.  Best coverage is
currently around HNB, but enough dying CBs near SDF and LEX that all
are worth initializing VCTS. Will also include a TEMPO for IFR vis
in heavy rain at HNB, and perhaps later this evening at SDF.  The
latter will be a last-minute call at issuance time.

Much of the overnight will be dry with light winds and a mid-level
ceiling. Precip coverage increases again just before daybreak with
the slow approach of the front. Look for low-end MVFR cig and vis
for a good chunk of the day under widespread showers. Best chances
for embedded thunder will be farther south and east in BWG and LEX,
so we`ll include VCTS there. Lowest ceilings expected at HNB and LEX
where we could go IFR at times. Will see breaks at times in the
rain, but not expecting improvement in ceilings until the last few
hrs of the TAF in HNB and SDF, and beyond that in BWG and LEX.


&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...BTN
Short Term...CJP
Long Term...JML
Aviation...RAS



Area Forecast Discussion...UPDATED

National Weather Service Memphis TN

 951 PM CDT Wed Jun 30 2021

.UPDATE...
Showers and thunderstorms dissipated over the Midsouth with the
loss of surface heating, and the extent of stabilizing outflow
from afternoon convection. At midevening, GOES IR imagery showed
showers and thunderstorms extending from the Ozarks into the Ohio
River valley. As midlevel heights slowly fall, some of this
activity will affect portions of the Midsouth, from northeast AR
through northwest TN. Overnight rain chances will be more limited,
but not out of the question, prior to 7 AM.

PWB

&&

.PREV DISCUSSION... /issued 709 PM CDT Wed Jun 30 2021/

UPDATE...

See the 00Z aviation discussion below.

PREV DISCUSSION... /issued 252 PM CDT Wed Jun 30 2021/

DISCUSSION...

Convection continues to develop across the Mid-South this
afternoon along the many outflow boundaries that are located
across the area. The latest run of the HRRR is still struggling
to initialize with what is occurring. Expect the numerous showers
and thunderstorms to continue into the early evening, but should
gradually dwindle near sunset due to the loss of daytime heating.
Locally heavy rainfall will be the main threat from the storms as
the storms are not moving much. Chances for convection will
continue especially across Northeast Arkansas, the Missouri
Bootheel, and Northwest Tennessee for the remainder of the night
as convection that is occurring across Missouri near the vicinity
of the approaching cold front begins to sink south into the
Mid-South.

The cold front will sink south into the Mid-South Thursday into
Thursday Night. Expect a repeat of today with numerous showers and
thunderstorms occurring across the area. Storms could become
strong during peak heating. Gusty winds and locally heavy rainfall
will be the main threats.

Drier air will begin to filter into the region on Friday behind
the front. Although, chances for showers and thunderstorms will
still occur across North Mississippi on Friday.

By Friday Night, SFC high pressure will begin to build into the
region. The high pressure will provide a beautiful Independence
Day weekend across the region. Expect low humidity with highs in
the 80s.

Humidity levels will begin to creep back up by Tuesday next week
as an upper ridge builds over the region. A weak disturbance may
get caught underneath the ridge which will bring rain chances back
to the Mid-South Tuesday into Wednesday.

KRM

&&

.AVIATION...
00Z TAFs

All showers and storms have died out in the past hour. Storms
currently over southeast Missouri may move into JBR around
midnight and weaken, while all other sites will remain dry
overnight. A cold front will approach from the northwest tomorrow
afternoon. SHRAs and TSRAs will begin scattered in the afternoon
hours and increase in coverage by early evening along a frontal
boundary. Lower CIGs and VSBYs will accompany the front as well as
prevailing SHRAs and TSRAs.

AC3

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$



Area Forecast Discussion

National Weather Service Phoenix AZ

 441 PM MST Wed Jun 30 2021

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Scattered showers and thunderstorms will be common over the
higher terrain and more isolated on the lower elevations the rest
of the week. Strong windS, localized blowing dust, and localized
heavy rain/flooding will be the main impacts. A slow decline in
storm activity begins by early next week. Temperatures will be
near, to slightly below, normal the rest of this week before
increasing a bit early next week.

&&

.DISCUSSION...
Strong convection developed early today, before 18Z, over the
northern AZ high terrain, with the strongest activity in the
Prescott area. An MCV also developed in southern San Bernadino
county CA and moved east through La Paz county this morning with
some embedded strong storms and moderate rain. The MCV is still
pushing east into portions of Maricopa county early this
afternoon, with an outflow pushing out ahead of it, but the
convection with it has mostly dissipated. Going forward through
the rest of the afternoon, the atmospheric flow pattern, dynamics,
and outflows may play a significant role in how convection
evolves.

Water vapor satellite shows a prominent upper level circulation
over the Great Basin and weak anticyclonic circulation over
northern Baja California. An enhanced gradient between the two
features may have aided the MCV this morning. A general divergent
flow pattern is seen over the central and eastern AZ with very
week steering flow. 850-300mb mean flow from RAP mesoanalysis is
around 5-10 kts out of the west to southwest. With the week
steering flow, storm motion will be slow and likely driven mostly
by outflows. With slow storm motions and non-existent shear,
ordinary storm modes are expected. With SBCAPE values upwards of
1000-1500 J/kg and PWATS around 1.2-1.5" analyzed over central AZ,
intense saturated updrafts are expected. As has already been seen
along the Rim and in Yavapai county. Strong storms may be brief,
suffering from waterloading, but still could produce significant
impacts. DCAPE is high, around 1000-1300 J/kg, over south-central,
so strong outflows will be a threat through the afternoon. 12Z HREF
probability of >35 mph is around 50-60% with max wind gusts around
45-55 mph, which seems a little low, but could be attributed more
to the moist environment. With the elevated moisture, slow storm
motions, and high instability, localized flooding impacts may be
the biggest concern this afternoon, especially with any storms
that become anchored to mountain peaks and ridgelines and/or
develop over burn scars. Rain rates may be a little tricky at
lower elevations, with HREF showing upwards of 0.5-1.0"/hr. A
gage near Crown King in Yavapai county measured ~1.0" in 10
minutes. So there is evidence of the potential for higher
rain rates.

A special 19Z sounding was launched out of Phoenix and shows a
virtually uncapped surface environment, with ~1000 J/kg SBCAPE,
~1.4" PWATS, and 10.6 g/kg mixing ratio. Forcing is the only thing
missing at this point. Storms so far have been limited to higher
terrain, but given the sounding, a strong outflow may be enough to
fire off storms over the lower deserts. Activity, in general is
not expected to last long past sunset this evening, dissipating
with the loss of heating.

.PREVIOUS DISCUSSION...
For Thursday, some sort of inverted trough may finally move deeper
into AZ - possibly aided by the sheared out mid/upper level
remnants of Enrique (weakens to a Depression today over southern
Gulf of California) and the westward advance of high pressure
centered to our east. The track, or even presence, of any such
perturbations remains quite uncertain. But, there may also be a
little bit more moisture to work with (associated with Enrique`s
influence). Ensemble data suggests a little bit more moistening
yet on Friday. As the moisture availability increases, the
potential for storms to produce heavy rain also increases. That
being said, the best precipitable water values look to be over
southwest AZ as opposed to south-central AZ. The threat would tend
to be pretty localized as well. Look for temperatures to be near
average.

A slow downtrend in moisture (PWAT) begins as early as Saturday or
as late as Monday. Meanwhile, the upper high centered over Texas
is advertised to become centered over Arizona over the weekend.
With weak steering flow and decreased instability, that would
tend to hinder storm development on the lower elevations. But, if
enough moisture lingers and steering flow isn`t too weak, there
could be a period of relatively better chances for the the
south-central AZ deserts. But, the high isn`t anticipated to be
super strong so we`re not anticipating an excessive heat event
through Tuesday.

&&

.AVIATION...Updated at 2345Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

An outflow boundary from the north has moved through most of the
TAF sites within the past hour or so, producing 15-25 kt northerly
(340-020) gusts. These gusts will likely continue for the next
hour or so before speeds begin to subside through the evening as
directions become northeasterly, and then easterly for the
overnight hours. A few showers have tried developing behind the
boundary but storm development continues to struggle over the
Valley, casting doubt for storms over any particular terminal.
Chances for storms in the terminal area and/or at any site is low,
between 10-20% now through 02Z, before  negligible later tonight.
Storms will continue to be more active north and east of the
Valley, potentially affecting arrival/departure gates, as well as
creating new outflows. For tomorrow, conditions will likely remain
in place for a "rinse and repeat" pattern with Thursday unfolding
similar to today.

Southeast California/Southwest Arizona including KIPL and KBLH:

There are no major aviation weather concerns through this TAF
period. At KIPL, southeasterly winds will predominate through much
of the period, at speeds of 8-13 kts, and occasionally stronger
gusts. Westerly afternoon winds may develop Thursday. At KBLH,
southerly winds will prevail with speeds frequently reaching 12-18
kts. Thunderstorm chances for either site are low, at around 10%,
with storms likely to remain well south of the US/MX border and
over the Kofa range in western AZ. These storms could send
outflows towards either site late tonight but confidence for that
occurrence is too low to mention in the current TAFs.

&&

.FIRE WEATHER...
Saturday through Wednesday:
High pressure is expected to become centered over Arizona over the
weekend. A slow decline in atmospheric moisture is also
anticipated to begin by early next week. Thus, the best potential
for storms with locally heavy rain looks to be this weekend.
Otherwise, a familiar Monsoon season pattern will be in place with
storms primarily focused over the higher terrain producing
outflows that spread to the lower deserts and in turn generate
isolated new storms. Temperatures will start off this period at,
or slightly below, normal followed by a a little bit of warming.
Min RH values will generally be in the 20-30% range through Sunday
before decreasing to 15-25% on Tuesday. Max RH values will follow
a similar trend but with decreases starting sooner. For instance,
Max RH values will be 40-60% most places (less eastern Riverside
County) through Monday morning before decreasing to 30-50% most
places by Tuesday morning. Apart from thunderstorms, wind patterns
will follow familiar diurnal patterns.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Benedict
PREVIOUS DISCUSSION...AJ
AVIATION...AD
FIRE WEATHER...AJ/Benedict



Area Forecast Discussion

National Weather Service Pueblo CO

 317 PM MDT Wed Jun 30 2021

.SHORT TERM...(This evening through Thursday)
Issued at 316 PM MDT Wed Jun 30 2021

...Heavy rains and marginal severe storms possible next 24 hours...

Currently...

Low level moisture has noticeably increased over the region during
the last 24 hours as dwpts over the region were in the mid 50s to
mid 60s across the plains, with 40s in the valleys. Scattered storms
were noted at 2 pm, mainly over the higher terrain, while showers
were noted over the plains extending SW-NE from KTAD to KLAA.
Ambient temps were in the 70s most locations in the valleys and
plains.

Rest of Today into Tonight...

Main concern is a wx disturbance moving northeast across the SW mtns
and heading towards the Pikes Peak region this evening. This
disturbance has initiated convection over the SW mtns and is
expected to cause areas of heavier rain over the Pikes Peak region
late this afternoon and especially this evening. Latest runs of HRRR
and NAM NEST guidance show up to 1 to 2 inches of rain will be
possible by this evening across the greater Pikes Peak region. It
should be noted that the hour by hour runs of the HRRR guidance has
been quite persistent with this solution throughout today.

Over the remainder of the region, showers and storms will be less
prevalent.

Tomorrow...

We should see a very active day across the region. A more
substantial disturbance is fcst to move through the region and
plenty of low level moisture will be in place. In addition...20-30
knts of shear will be in place and winds at jet level will be rather
strong. A favorable theta-e axis (1000-2000 J/KG CAPE) is forecast
to run from the Pikes Peak region down towards KSPD, with this
favorable instability feeding the convection which is expected to
initiate over the mtns by mid afternoon. Given these favorable
thermodynamic fields which will be in place, we are going to see two
weather threats affecting the region tomorrow. The first will be
heavy rain capable of producing flash flooding over the greater
Pikes Peak region (including Fremont/Wet mtns/Pueblo/Pikes Pear
area); with the 2nd threat being severe thunderstorms over most of
the plains. The most favorable corridor for severe will be from KCOS
to KSPD along the favorable theta-e axis. All svr wx types will be
possible as LCLs will be rather low. It is not out of the question
that 1-3 inches of rain could occur. This potential heavy rain,
combined with the locally heavy rain which is expected to fall this
evening, will allow for the potential of flash flooding, and a flash
flood watch has been issued.

Guidance has been consistent at pegging the area mentioned above for
the heavy rain for the last several days, and confidence is rather
high that flash flooding will be possible tomorrow, especially if
locally heavy rains fall this evening in the Pikes Peak region.

.LONG TERM...(Thursday night through Wednesday)
Issued at 316 PM MDT Wed Jun 30 2021

Main Forecast Concerns/Challenges:

1) Heavy rain threat Thursday night with possible continuation into
Friday

2) Daily chance for thunderstorm activity, especially over the
mountains

3) More seasonal temperatures return by Saturday

Thursday night through Friday...As a continuation of all that was
mentioned in the short term discussion about tomorrow, an abundance
of llvl moisture and favorable dynamics means that both a heavy rain
threat as well as a severe threat will likely continue well into the
evening tomorrow. The question that remains to be answered will be
where the precip bullseyes will eventually fall. Activity will
likely persist until after midnight, though the heaviest rainfall
should taper off just prior, and the current end of the watch at 11
PM looks reasonable. A less volatile scenario is forecast for
Friday, though llvl moisture will remain in place, there will be
lighter southeast surface flow and the upper ridge of high pressure
will be slow in gathering strength. Therefore, showers and
thunderstorms will once again initiate over the eastern mts right
around midday. Temperatures are forecast to warm into the 70s to
around 80F for most locations.

Saturday through Monday...An upper level ridge of high pressure
builds over the Four Corners region, and strengthens over the
holiday weekend. There will be a daily shot of convection, mainly
tied to the higher terrain, developing during the aftn and
persisting into the evening. Flash flooding threat to area burn
scars will need to be assessed on a day to day basis, as it will be
hit and miss due to the convection. Temps are forecast to start
climbing back up to seasonal normal levels as well, with highs in
the upper 70s to lower 80s for the high valleys, and in the 80s to
around 90F for the plains.

Tuesday and Wednesday...The upper ridge remains strong but shifts
slightly to the west, as an upper disturbance crosses MT, WY, the
Dakotas and NE both days. This shortwave will help enhance
convection chances as well as areal coverage both afternoons, but
especially for Tue where QPF values increase significantly. Temps
are expected to remain at seasonal levels. Moore

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 316 PM MDT Wed Jun 30 2021

Thunderstorms will be more prevalent over the region starting
later today and lasting into the Holiday weekend. The overall best
chance of thunderstorms capable of heavy rain, gusty winds and
possibly small hail will be in the Pike Peak region late this
afternoon and evening and especially tomorrow afternoon and
evening. MVFR to brief IFR will be possible in the heavier storms
which will occur.

At KPUB, thunder chances today ar quite low, but there will be a
much better chance of strong storms tomorrow afternoon.

At KALS, only isolated afternoon and evening activity is possible.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from Thursday afternoon through Thursday
evening for COZ076-077-079>086.

&&

$$

SHORT TERM...HODANISH
LONG TERM...MOORE
AVIATION...HODANISH



Area Forecast Discussion

National Weather Service Blacksburg VA

 915 PM EDT Wed Jun 30 2021

.SYNOPSIS...
Upper ridge begins to shift southward tonight as a cold front
slowly approaches from the northwest to end the week. Unsettled
weather is likely Thursday afternoon into Friday night with this
storm system.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 900 PM EDT Wednesday...

 Adjustments mad for latest radar trends...

Last few runs of the RAP had a good handle on the location of
storm development. Used this and current radar trends to add
isolated to scattered thunderstorms from the New River Valley to
the southern Shenandoah Valley through 03Z/11PM.

Upper ridge centered across VA/NC will shift southward tonight
as a trough digs across Ontario/Quebec into the Great Lakes.
Overnight lows will also run warmer than normal by 5F or so,
basically mid to upper 60s west of the Blue Ridge to lower 70s
east.

We start to loss the influence of the upper level ridge
Thursday afternoon as it sinks further to the southeast.
meanwhile, an upper level trough over Ontario/Quebec will slowly
push a cold front across the Ohio Valley. This front will
introduce a good chance for showers and thunderstorms to the
western slopes (Bluefield to Lewisburg) by mid afternoon. For
the rest of the mountains, scattered storms are possible in the
afternoon and maybe an isolated shower east of the Blue Ridge.

If storms move into the mountains during the afternoon, high
temperatures will be cooler than the previous couple of days.
With the expectation of storms arriving in the afternoon, highs
across the mountains should range from the upper 70s to mid 80s.
With less of a chance of rain east of the Blue Ridge,
temperatures will once again be warmer than normal with highs in
the low to mid 90s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 200 PM EDT Wednesday...

     Numerous showers and storms with a slow moving cold front
Thursday night into Friday. Drying out for the start of the weekend...

An active stretch of weather ahead over the next 24 to 48 hours
as a slow moving cold front and upper level low pressure system
roll our way. The main focus will be Thursday night into Friday
when the bulk of our stormy weather looks to arrive. Locally
heavy rainfall is likely along with localized flash flooding
concerns. This is due largely in part to PWATS running anywhere
between 1.5 to 2.0 inches across the area out ahead of the cold
frontal boundary which will be further amplified by a deepening
upper level low pressure system and it`s adjacent upper tough
digging down from the eastern Great Lakes region. With all that
said, the Weather Prediction Center has areas along and west of
the Blue rIdge in a slight risk for excessive rainfall. Areas
out east are also highlighted in marginal risk for excessive
rainfall. This simply means that the airmass in play is very
moist and muggy with a lot of water to dump out. This is further
addressed in detail in the HYDROLOGY section below.

As for rain amounts, we can look for a widespread swath of at
least 1.5 inches to 2.5 inches across the area. Localized
heavier pockets of 3 inches or better can be found across
portions of the Greenbrier Valley back into the Mountain Empire
and along the southern Blue Ridge. The good news is that we have
been dry the last few days which should minimize the flood
threat to a degree. WIth rainfall amounts of at least 1"/hr or
better localized instances of flash flooding looks to be the
biggest concern especially where we can get slow moving
thunderstorms to line up.

Our severe weather threat looks to minimized based on current
12z guidance shoving in the clouds and precipitation a bit
faster heading into the front half of Thursday. The threat is
not zero though especially across northern and eastern portions
of our area where the better dynamics can be found. Forecast
MLCAPE values per KIAD, KRNK, KDAN, and KRIC sit between
1,000-2,000 j/kg with DCAPE values upwards of 700 j/kg Thursday
evening into the overnight. The threat will quickly decrease by
Friday as the front continues south and east.

Any widespread shower or thunderstorm activity should come to
an end late Friday evening into Friday night as the front sags
south and deepening upper level low swings north and east. On
Saturday, the axis of the upper level trough will pivot through
with it`s resultant cold pool aloft. This will keep isolated
diurnal shower/storm chances in play on both Saturday and SUnday
afternoon. Most of this will be confined to the mountains where
better forcing can be found. Most locations look to remain dry
with partly to mostly cloudy skies Saturday afternoon.

Temperatures will be at or slightly below average through the
period. Highs will top out in the low to mid 70s in the west
with mid to upper 70s out east Friday under cloudy skies. More
sunshine Saturday gets temperatures close to 80 degrees.
Overnights lows will bottom out in the mid to upper 50s.

Confidence remains moderate in the short term based upon the
placement of the front and upper level low pressure system. Some
uncertainty remains in regards to rainfall amounts and the
flood threat based upon the dry conditions over the last several
days.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 230 PM EDT Wednesday...

 Mainly dry with a warming trend expected July 4-7.

After a cool start Sunday, temperatures will rebound with a
return to seasonal heat and humidity. The upper level pattern is
forecast to deamplify, the eastern long wave trough lifting
northeast and away from the forecast area. In response, heights
will increase, along with temperature and dewpoints. By mid-week
enough moisture should return to support a few pop-up
showers/thundershowers during the afternoon/evenings with
highest pops over the mountains, but even then, expecting less
than 30 percent coverage.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
As of 120 PM EDT Wednesday...

Isolated to scattered thunderstorms with some MVFR to IFR
visibility due to very heavy rain will continue until around
03Z/11PM. Used the last few runs of the RAP and radar trends for
timing and placement of the showers and storms. May add to
KLYH at least in the vicinity before midnight.

MVFR to IFR fog is possible in the early morning where it rained
this evening. Ceilings overnight will be VFR.

Numerous showers and thunderstorms are expected on Thursday,
especially after 18Z/2PM with MVFR ceilings and visibility.

Above average confidence on ceiling, visibility and wind.
Average confidence on the timing and location of thunderstorms
this evening.
Below average confidence of occurrence of fog overnight.

Extended Aviation Discussion...

Active weather is expected through Friday night as a cold front
slowly works its way through the region from the northwest to
southeast.

Greatest confidence for sub VFR is Thursday night and Friday,
associated with numerous showers and scattered thunderstorms.
Improvement is expected Saturday and especially Sunday.

An upper low is expected to cutoff over the Great Lakes and
Ohio Valley this weekend which may cause unsettled weather to
persist into the weekend, though should be VFR most of the time.

&&

.HYDROLOGY...
As of 100 AM EDT Wednesday...

The region will have the potential for locally heavy, potentially
flooding, rains for parts of the area Thursday afternoon into
Friday Knight. Several atmospheric features are aligning in a
way which favors such an outcome:

1) Forecast Precipitable Water is expected to be near 2.00
inches. Such values are between +1 to almost +2 sigma of normal
for the start of July via NAEFS and place higher than the Daily
Max moving average (1.66 inches) off the SPC Sounding
Climatology Page for Blacksburg, VA.

2) Immediately preceding and coincident to the advancing cold
front, 850mb-300mb Bulk Shear will be relatively weak and
aligned nearly parallel to the front, thus allowing for training
of showers/storms,

3) The majority of the precipitation is expected to fall across
the region Thursday night through Friday evening with average
amounts on the order of 1.25 to 2.25 inches with locally
heavier amounts closer to 3.00 to 4.00 inches along some of the
mountain ridges. The combination of steep terrain, and locally
heavy, potentially training rainfall, can result in flooding
issues.

4) The folks at the Weather Prediction Center are examining
locally heavy rain concerns for our area as well. Within their
Excessive Rainfall Forecasts for Thursday through Thursday
night, they have placed Marginal Risk of flooding in areas
generally east of the Blue Ridge, and a somewhat more concerning
Slight Risk for areas generally along and west of the crest of
the Blue Ridge. For Friday, A Marginal Risk is in place for
counties along the VA/NC border and the piedmont of central VA.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...RCS
NEAR TERM...AMS/RCS
SHORT TERM...ET
LONG TERM...PM
AVIATION...AMS/RCS
HYDROLOGY...DS



Area Forecast Discussion

National Weather Service San Diego CA

 155 PM PDT Wed Jun 30 2021

.SYNOPSIS...
Isolated thunderstorms over the San Diego mountains today will
dissipate this evening. Isolated convection is again possible
Thursday. Coastal areas will be mired in June gloom through the
weekend as a coastal eddy and a shallow marine layer limit clearing
at the coast. The valleys, mountains and deserts will be warm this
weekend with occasional mid and high clouds.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Towering cumulus formed over the mountains today, growing tall
enough to generate a thunderstorm near Pine Valley and Mt Laguna
between Noon and 1 PM. Farther north in Riverside and San Bernardino
County the cumulus hadn`t grown tall enough for precipitation
through 1 PM.

Moisture convergence was highest in San Diego County where dew
points were in the mid to upper 50s. Dewpoints were lower in
Riverside County (40s and low 50s), and they were even lower in the
San Bernardino Mountains (30s and 40s). This drier airmass will push
a little farther southeast Thursday, limiting the T-storm potential
primarily to San Diego County. Precipitable water over the San Diego
County mountains today was 0.94", tomorrow it is forecast to be
0.90". The high resolution HRRR and WRF models show isolated
convection tomorrow afternoon, but with less coverage than today.
Dry lightning and strong wind gusts are the most likely threats.

Friday through Sunday: A Four Corners high rebuilds over the
Southwest bringing warmer days over the holiday weekend. Valley,
mountain and desert temperatures will be a little warmer than
average, but the coastal areas will be a little below average due to
a persistent marine layer that will limit clearing at the coast each
afternoon.

Southeast monsoonal flow also increases over the weekend which will
bring mid and high clouds. The westward extent of the deep moisture
is still in question, but most of the long range guidance is dry.

&&

.AVIATION...
302030Z...Coast/Valleys...The coastal terminals are likely to see
BKN-OVC conditions through the afternoon. Low clouds spreading back
inland after 01/00Z with bases near 700-1200 ft MSL and tops to 1700
ft MSL. Ceilings are expected to be a little lower on tonight and
Thursday morning and stratus spreading further inland possibly as
far as KONT. Skies will clear for all but the immediate coast 15-18Z
Thursday. Thunderstorm activity is not expected to impact the
coast/valleys.

Mountains/Deserts...Isolated TSRA will continue through 00Z mainly
over the mountains with CB bases at 10,000 FT MSL and tops to 30,000
FT MSL. The primary threat will be strong up/downdrafts and local
surface gusts of 40 kt. The storms are expected to remain primarily
over the mountains with only a low chance of moving eastward into
the deserts. Will not mention thunder KPSP/KTRM due to low
confidence of desert impacts. Isolated TSRA expected again Thursday
afternoon, but less coverage than today.

&&

.MARINE...
No hazardous marine conditions are expected through Sunday.

&&

.BEACHES...
Expect a high rip current risk through the holiday weekend given the
persistent long period south swell. Surf heights will peak Monday/
Tuesday in the 4 to 6 foot range.

&&

.FIRE WEATHER...
Isolated thunderstorms with dry lightning and gusty winds over the
mountains through early evening, drifting east over the deserts. The
moisture decreases Thursday and the greatest chances will be over
the San Diego and Riverside County mountains. That drying trend
will continue into Friday.

Southeast monsoon flow returns over the weekend, but the moisture
will once again be elevated. The forecast model are showing
increasing mid and high level clouds, but the thunderstorm chances
remain low.

&&

.SKYWARN...
Skywarn activation is not requested, but weather spotters are
encouraged to report significant weather.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC/FIRE WEATHER...Moede
AVIATION/MARINE...Moreland



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