Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/22/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
810 PM CDT Fri Jul 21 2023
.UPDATE...
Issued at 809 PM CDT Fri Jul 21 2023
Forecast is in good shape this evening, only minor mods made to
it.
&&
.SHORT TERM...(This Evening through Saturday Night)
Issued at 238 PM CDT Fri Jul 21 2023
A shortwave currently over the ND, MN border is interacting with
weak instability to produce isolated to scattered showers, mainly
east of I-29. Limited lightning strikes have been observed so far.
CAMS suggest isolated coverage possible yet this afternoon
further west, perhaps as far west as Highway 83. The showers
should dissipate around sunset. Dry conditions with seasonal low
temperatures can be expected overnight.
Additional showers and thunderstorms are possible again on Saturday
over the eastern half of the CWA. Another shortwave should track
southeastward across the region early in the day, producing an
isolated thunderstorm threat. Lightning will be the main threat. The
HRRR vertically integrated smoke shows a good amount of smoke
crossing the region on Saturday, which could limit the potential
heating. Did increase sky cover to account for the elevated smoke.
.LONG TERM...(Sunday through Friday)
Issued at 238 PM CDT Fri Jul 21 2023
Hot temperatures start to take over at the start of the extended
period, with upper ridging building eastward across the Northern
Plains through early next week. Once the heat settles in, it appears
850 mb temps in the +20s C will remain in place perhaps through the
rest of the period. By mid-week when the peak of the heat is
expected, look for widespread highs in the 90s to around 100
degrees. Various ensemble output for probs of 100 degrees or more
are showing up throughout the extended period, although GEFS is most
aggressive in its percentages. Given forecast dewpoints, there still
appears to be a few periods throughout the extended where we may
need to worry about heat headlines as heat indices approach/eclipse
100 degrees.
As for precipitation, there doesn`t appear to be any strong waves
set to affect the area, although will have to watch a few smaller
disturbances that warrant slight chance POPs. Ridge-rider wave for
mid-week may be the "best" chance for rainfall across the region,
but much too soon to know any specifics on this yet. There`s some
evidence of a surface reflection tied to this, with perhaps some
boundary to work off of. For now, forecast remains at slight chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 616 PM CDT Fri Jul 21 2023
Terminals KABR,KATY,KPIR,KMBG
Expect VFR skies/vsbys through tonight.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...SD
LONG TERM...TMT
AVIATION...TDK
Area Forecast Discussion
National Weather Service Denver/Boulder CO
859 PM MDT Fri Jul 21 2023
.UPDATE...
Issued at 854 PM MDT Fri Jul 21 2023
An upper level jet in NW flow aloft combined with MLCAPE around
1000 j/kg has allowed for a few stg to svr storms this evening
over nrn portions of the I-25 corridor. These storms were moving
across the plains this evening and may linger thru at least
midnight.
&&
.SHORT TERM...(This afternoon through Saturday)
Issued at 1028 AM MDT Fri Jul 21 2023
A much quieter afternoon across Colorado versus yesterday given a
drier and subsident northwest flow pattern. Latest radar showing
an isolated shower/storm trying to brew across Jackson county and
isolated thunderstorms further north across Wyoming. There is
still enough moisture and marginal instability for isolated
thunderstorms over mountains and higher terrain, especially over
the CYS ridge. Latest HRRR and recent runs insistent on a storm
forming just over the border and into northern Weld and Morgan
counties through this evening. Will have isolated pops through
this evening for mountains and adjacent plains. The far northeast
plains look to be too capped for any storms. Any storms that do
form will diminish quickly by late evening with loss of solar
heating and subsident airmass.
Saturday looks to be similar to today with mainly dry conditions and
warming temperatures. High pressure ridge aloft remains west of
Colorado and continues to build across the Great Basin. Thermal
ridge building from the west with 700mb temperatures rising another
2-4 degrees C. This will support high temperatures around 90
degrees on the plains. The convective outlook is pretty sparse
with mayhap a few weak showers/storms over the mountains and
higher terrain.
.LONG TERM...(Saturday night through Thursday)
Issued at 230 PM MDT Fri Jul 21 2023
Key message: Summer heat is here for a lengthy stay.
A ridge of high pressure will dominate the region for the next
several days to come. The upper level high will shift slowly
eastward over the Southern Rockies through the weekend, while a
rather high amplitude ridge will extend northward from that
across Colorado and into the Northern Rockies/High Plains. This
pattern will bring a return of hot temperatures to the forecast
area, with highs pushing into the mid to upper 90s and possibly a
couple 100F degree readings across the plains and I-25 Corridor
for Sunday and Monday. The airmass will remain relatively dry,
although expect a few high based showers and storms late Monday as
moisture slowly builds under the ridge.
By Tuesday and Wednesday, a shortwave will move across the
Canadian/US border, flattening the ridge just a bit. That should
also drag mid level moisture across the forecast area increasing
the chance of showers and storms. We don`t see any big monsoonal
push with this, but just enough for a little higher coverage of
precipitation. Most storms will likely only produce light rain
with gusty winds considering lack of low level moisture and
inverted-v profiles. Temperatures will remain above normal with
mostly lower to mid 90s over the plains and I-25 Corridor, just a
couple degrees cooler thanks to increasing moisture and a few
late day storms around.
Thursday could have a chance of a little more cooling with
potential for a backdoor cool front. At the same time, we could be
looking at increasing fire weather potential for the high country
as westerly flow increases in the wake of the passing shortwave.
For Friday and probably through next weekend, we`re shaping up for
more heat as prognostications show a 600dm high building over the
Four Corners area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 541 PM MDT Fri Jul 21 2023
At this time don`t expect isold tstms to the NW and North to
affect DIA. Otherwise look for winds to become more southeast
in the next few hours and then go to drainage by 06z.
&&
.HYDROLOGY...
Issued at 230 PM MDT Fri Jul 21 2023
The hi-res models generate the best thunderstorm coverage over
Larimer County today, so the flash flood risk for Cameron Peak
will be limited, with minimal risk elsewhere. Only isolated
showers are expected on Saturday afternoon over the burn scars
with little or no chance of flash flooding.
Drier conditions expected, although a few storms will develop
toward Monday through the middle of next week. For the most part
these storms will be weak and only produce light rain, and little
or no threat of flash flooding even in the burn scars.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...Barjenbruch
AVIATION...RPK
HYDROLOGY...Entrekin/Barjenbruch
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
254 PM PDT Fri Jul 21 2023
.SYNOPSIS...Hot temperatures will continue across the interior
through Saturday while the coast will see seasonably cool
temperatures. Temperatures will then gradually cool through early
next week, but interior temperatures will remain near to above normal
through the rest of the period. No rain is forecast to occur during
the next seven days.
&&
.DISCUSSION...Today began will widespread stratus over the coastal
waters once again, with mostly clear skies inland. Stratus continues
along the North Coast as of this writing, with the best inland
penetration over the Eel River Delta. The marine layer started the
day about 2000 ft deep, but it has become a bit shallower (about 1500
ft) during the afternoon. Temperatures this afternoon range from
some lingering upper 50s along portions of the immediate coast to
just over the century mark across portions of Lake and S Mendocino
counties. Smoke from the Flat Fire of SW OR continues to spread S
into our County Warning Area (albeit still mostly thin). Have
continued to populate HRRR smoke guidance to account for visibility
reductions.
A large upper low continues to meander near 50N/140W. A sprawling
upper ridge extends from the S Plains to CA and the E Pacific.
Although the hottest temperatures in our area are expected this
afternoon over Lake and extreme E Mendocino counties, heat will
continue into Saturday with highs just below Friday`s values.
The latest NBM guidance has continued to run a bit lower than all
deterministic MOS. Have adjusted daytime highs toward at least the
low end of these numbers. As a result, have left the Heat Advisory
for Lake County unchanged. Temperatures will continue the slow
decline into next week.
Along the coast, stratus will continue through most of the period,
although at least partial clearing is expected in many locales
each day. Patchy drizzle is possible again tonight from Cape
Mendocino N to Humboldt Bay. Local tools suggest that this will
continue to be possibility most nights and mornings into the
weekend. Mostly trace amounts of rainfall are expected, with
locally a hundredth or two. The low-level inversion is forecast to
gradually weaken late in the weekend and early next week. /SEC
&&
.AVIATION...Under building high pressure, the marine layer is
becoming more shallow under a strengthened low level inversion.
Limited scattering will give way to OVC shallow stratus at IFR
levels, with movement into LIFR. Ceiling heights have struggled to
exceed 500 ft AGL this afternoon, with some shallow 200 fT CIG
development at ACV. Timing of LIFR may require an earlier start in
the 0Z TAF issuance. TEMPO FG looks probable overnight, particularly
in the early morning hours of Saturday. Additionally, slant range
visibilities at CEC and ACV will be reduced due to wildfire smoke
from southwest Oregon.
&&
.MARINE...Conditions in the northern waters this afternoon consist
of advisory level northerlies in the outer waters with general gusts
to 25 kt, and isolated gusts closer to Point St George up to 29 kt.
Short period seas are 3 to 5 ft, with isolated 6 ft around Point St
George. Conditions in the southern waters consist of 20 to 25 kt
northerlies, with gale winds gusting up to 40 kt south of the cape.
The gale coverage will contract early Saturday. Similar conditions
will carry through the weekend. Winds and seas will trend down by
Sunday night from an approaching trough. Advisory level northerlies
are forecast to redevelop late Tuesday or Wednesday.
&&
.FIRE WEATHER...Interior winds are forecast to remain fairly light,
but W to NW up-valley winds may become gusty through channeled
terrain and exposed ridges each afternoon into early next week. The
driest air and poorest nighttime recoveries are expected tonight
across eastern portions of fire wx zones 264 and 277. Have continued
near-critical headlines in both these zones. Dry weather will
continue through the weekend, but with a gradual cooling trend. /SEC
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 11 PM Saturday for CAZ114-115.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 9 AM Sunday for PZZ455-470.
Small Craft Advisory until 3 PM this afternoon for PZZ475.
Gale Warning until 3 AM Saturday for PZZ475.
$$
Visit us at https://www.weather.gov/eureka
Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka
For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Forks ND
1017 PM CDT Fri Jul 21 2023
.UPDATE...
Issued at 1017 PM CDT Fri Jul 21 2023
Showers have diminished in all but just a few locations in the
Devils Lake Basin. Look for quiet weather through much of the
overnight period, along with lows falling into the 50s to near 60
degrees.
UPDATE Issued at 613 PM CDT Fri Jul 21 2023
Isolated showers and thunderstorms ongoing this afternoon are
expected to diminish in the next couple hours. Most of the
activity thus far has been along and west of the Red River Valley;
however, these showers are slowly pushing to the east.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 232 PM CDT Fri Jul 21 2023
Key Messages:
- Isolated to scattered showers and thunderstorms will continue
around the area this afternoon into early evening. Strong to severe
weather is not anticipated.
- Saturday holds additional chances for isolated to scattered
showers and thunderstorms, this time favoring portions of northwest
and central Minnesota.
- Smoke is forecast to continue filtering into the area through
the weekend.
Discussion:
A couple mid level impulses/shortwave troughs will across our area
within northwest flow aloft. At the surface, a trough/boundary
will push through from the northwest late tonight into Saturday
morning. This along with convective temps being met during the
afternoons, meager but sufficient moisture, and weak instability
will promote isolated to scattered showers and thunderstorms.
Given weak instability at or below 1000 J/kg, and shear near or
below 25 kt, the chance for organized strong to severe storms are
low, less than 5%.
While chance for convection will be area-wide today, Saturday will
favor locations closer to northwest Minnesota into central
Minnesota during the morning into early afternoon based on
guidance`s track and timing of the boundary/forcing mechanism.
While not anticipated, should better shear eek into our areas near
central Minnesota during the afternoon, there is a small chance
some semi-organized storms could develop to bring small hail,
however this scenario holds around a low, 10% chance of
occurring.
Otherwise, smoke is forecast to continue filtering into the area
given northwest flow aloft. Guidance offered by HRRR and RAP
indicate some of this smoke could reach the surface, however the
bulk of thicker smoke is forecast to remain aloft.
.LONG TERM...(Sunday through Friday)
Issued at 232 PM CDT Fri Jul 21 2023
Key Messages:
- There remains a low (20%) chance for excessive heat between
Tuesday and Thursday next week.
- While predictability remains low, there is a conditional chance
for one or more periods of organized strong to severe
thunderstorms next week, starting as early as Sunday.
Discussion:
Ensemble guidance continues to strongly agree in broad upper
ridging to build over the western two thirds of the CONUS next
week. This will likely feature a dome of excessive heat and
relatively high moisture content building over portions of the
Central Plains and Midwest, with a belt of enhanced winds aloft
rounding the crest of the upper ridge.
Differences within ensembles lie within mesoscale details like
location and timing of surface convergence zones/boundaries as
well as synoptic differences like how subtle, small and
progressive shortwave troughs move through the crest of the upper
ridge, in addition to their influence to augment the axis and
strength of the upper ridge itself.
Regarding the chance for excessive heat, there remains around 20%
chance for excessive heat with heat indices exceeding 100 F
between Tuesday and Thursday, as offered by cluster guidance. A
stronger ridge, with axis tilted over our area would favor this
solution. Still, the duration of the potentially excessive heat is
strongly favored to be short in duration (less than 12 hours for
any one location). Regardless of excessive heat, there is a high
chance in warming, above average temperatures into our area
between Tuesday and Thursday, and perhaps into late next week,
with highs advertised into the 80s and 90s.
Regarding the conditional chance for period/s of organized strong
to severe storms, guidance and climatology suggests there will be
one or more periods of these storms next week, starting as early
as Sunday. With increased chance for instability to work its way
into our area offered by a nearby reservoir of high
heat/moisture/theta-e air mass, and the belt of enhanced winds
aloft, it is reasonable to believe this chance exists should any
forcing sufficient enough to sustain organized convection. It is
this forcing aspect that remains in question.
Some guidance suggests forcing could be strong enough to sustain
lift and overcome any potential capping issues as early as Sunday.
While any surface boundary location and amount of forcing remain
in question, a wide range of scenarios could develop regarding
storm mode and thus hazards. One scenario depicts morning MCS to
move near or through the area which would favor gusty winds.
Another, more impactful scenario would be discrete supercells (as
offered by WRF-FV3) due to a sweet spot of just enough forcing to
overcome capping, while suppressing widespread updrafts to disrupt
cellular activity. Strong to very strong shear, unidirectional
shear with strong storm relatively flow in the low and upper
levels, deep inflow layers, sufficiently moist and warm low
levels, and an glancing blow of an EML out of the northern High
Plains all spell potential for significant hail should discrete
mode be maintained on Sunday. Again, this is conditional, but with
the potential for significant hail/impacts, it is worth
mentioning even if it is low in probability (10%).
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1017 PM CDT Fri Jul 21 2023
VFR conditions prevail through the period at all sites. Light and
variable winds are expected overnight, with a chance for showers
working into portions of the area just before sunrise Saturday.
Winds are expected to pick up out of the north by midday
Saturday at 7 to 12 mph.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Lynch
SHORT TERM...CJ
LONG TERM...CJ
AVIATION...Lynch
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1044 PM CDT Fri Jul 21 2023
.SYNOPSIS...
Issued at 1044 PM CDT Fri Jul 21 2023
Mild summer weather will continue through the weekend with just a
slight chance of a shower or storm Saturday night and Sunday, but a
warming trend will begin to kick off the upcoming work week which
could turn quite hot by Wednesday. Still, any day next week one
could see a stray thunderstorm which could bring a temporary
reprieve from the heat.
&&
.UPDATE...
Issued at 800 PM CDT Fri Jul 21 2023
Early evening surface map indicated high pressure over the central
Plains with ridging extending east into northern IL. As the
nocturnal inversion deepens tonight winds are expected to go
light/variable or calm. With dewpoint depressions dropping near
zero after midnight we expect fog to form, then dissipate within
an hour or two after sunrise. This should be mainly light/patchy
fog with visibility 3-5 miles and available guidance shows very
low probabilities of dense fog. Lows will be similar to last night
in the upper 50s and lower 60s.
25
&&
.DISCUSSION...
Issued at 252 PM CDT Fri Jul 21 2023
------------------------- [Key Messages] -------------------------
1. Slight (~20%) chance for a shower or storm Saturday
evening/night. 30-40% chance (highest east) Sunday.
2. Sporadic 20-30% chances for thunderstorms next work week.
3. Temperatures on a warming trend next week. Predictability remains
low, but there is concern for excessive heat by mid-late week. Any
thunderstorms, however, could bring brief relief from the heat.
-------------------------- [Discussion] --------------------------
Cool northerly flow continues this afternoon as weak surface high
pressure gradually builds in behind the cold front which has already
pushed through western Kentucky and Tennessee (evident by the sharp
dewpoint gradient there). The much drier air mass in place behind
the front will foster steep low level lapse rates where surface
heating is maximized, which could lead to some widely scattered
instability-driven showers tomorrow afternoon. NBM and HREF each
suggest those probabilities, however, are only on the order of
about 20-30%, and fortunately the dryness of the air mass will
preclude any robust instability for strong storms. In fact, the
CAPE profile tomorrow from forecast soundings is looking pretty
"skinny," indicating low NCAPE values which probably won`t even
support much thunder potential. HRRR simulated reflectivities show
a couple tiny specks of 30-40dBZ dotting the CWA in the evening
becoming a little more widespread Saturday night into Sunday
morning as a weak disturbance at 500mb ripples through to provide
a little more upper level support on the southwest fringe of an
upper trough anchored over the northeast CONUS. By Sunday evening,
it appears the trough will be shifting east sufficiently to shunt
away our precip, though the deterministic GFS is still hinting
there could be a stray shower somewhere, particularly across our
east. This afternoon/evening activity will need to be watched, for
though 0-6km shear values are only forecast to reach about 25 kt
SBCAPE values are progged to reach 2000+ J/kg per the NAM`s
forecast sounding, and DCAPE values are forecast to reach 1100
J/kg or more thanks to some dry air in the mid levels and steep
low level lapse rates which could pose a localized gusty wind risk
with any collapsing showers/storms.
Beyond Sunday, there`s actually quite a bit of uncertainty in how
the pattern will evolve. There`s definitely an overall warming trend
evident in the low resolution ensemble forecast (LREF) system, which
is the combined ensembles of the GFS (called the GEFS: 30 models
called "members"), ECMWF (called the EPS: 50 members), and CMC
(CMCE: 20 members). In fact, NBM`s deterministic forecast, which is
essentially the mean of the biased corrected LREF, brings high
temperatures up from 89 degF Monday to 94 degF by Thursday in
Lincoln. However, the 10th to 90th percentile range (the observed
high temperature should fall into this range 80% of the time if its
properly calibrated) spans 10+ degF Monday and nearly 15 degF by
Wednesday, suggesting significant spread in the ensemble. As has
been the case the past several days, the GEFS continues to be the
outlier of the three ensemble systems comprising the LREF (and
ultimately feeding NBM), with most of its members yielding maxTs >
95 and upwards of 20% of its members depicting 105+ degF highs at
KAAA by next weekend. These outliers (some of which are > 110!)
are skewing the data and pulling the ensemble mean (and hence NBM)
up above what would seem reasonable given the moisture flux which
could be expected from agricultural evapotranspiration this time
of year (even given our still semi-dry soils). So...temperatures
were nudged 30% to the 25th percentile to bring them back in line
with what the rest of the LREF is suggesting for Thursday and
Friday. Even so, our highs could be far too warm should we get
convection - which the deterministic models are suggesting could
crest the ridge at any time during the upcoming work week.
Convective action could not only bring a very temporary relief to
the heat, but it would also yield outflow boundaries which could
push the periphery of the ridge back towards the south -- possibly
preventing it from building in nearly as much as what the models
have been suggesting. We`ll continue to monitor and update the
forecast (and discussion) with our latest thinking.
Bumgardner
&&
.AVIATION... (For the 06z TAFs through 06z Saturday Night)
Issued at 1044 PM CDT Fri Jul 21 2023
Calm wind and mostly clear skies will promote light fog formation
later tonight. MVFR visibility is forecast from around 08-12z.
Cannot rule out patchy/transient drops to IFR but probabilities
are too low to include in TAFs. Otherwise light winds and diurnal
cu will dominate the area Saturday afternoon. An isolated
afternoon shower or storm is possible but chances of impacting a
terminal are very low.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Medford OR
505 PM PDT Fri Jul 21 2023
.UPDATE...Updated the aviation section.
&&
.AVIATION...22/00Z TAFs...A thin IFR marine layer extends over the
coastal waters and immediate coast from Cape Blanco northward. It
will thicken, and extend into the Coquille and lower Umpqua valleys
overnight into early Saturday morning. This includes North Bend. A
few early morning patches of IFR may also briefly develop in the
southern and eastern portion of the Umpqua Valley...to the south and
east of Roseburg.
Smoke from the Flat Fire will be present over much of the area, but
reductions to MVFR visibility are expected to be limited to Curry,
western Josephine, and far northwest Siskiyou counties.
VFR conditions under clear skies are expected over the rest of
southern Oregon and northern California through the TAF period.
-DW
&&
.MARINE...Updated 200 PM PDT Friday, July 21, 2023...A Small Craft
Advisory continues for south of Port Orford between roughly 2 nm out
to 40 nm from shore through early Saturday.
A thermal trough dominated pattern will persist through the weekend
into early next week. The thermal trough will be of weak to moderate
intensity, with winds remaining strongest south of Cape Blanco. This
thermal trough will dissipate Sunday night which will make for light
winds for all the coastal waters early next week. -Sargeant
&&
.PREV DISCUSSION... /Issued 235 PM PDT Fri Jul 21 2023/
DISCUSSION...At the large scale, the region is currently between
the high pressure ridge that often builds over the Four Corners
region and a very broad low pressure system in the Gulf of Alaska
off the coast of British Columbia. The ridge has retrograded
slightly, and under its influence we`re seeing above average
temperatures in the 90s and low triple digits through the region.
Smoke from the Flat Fire near Agness has reflected enough
insolation today that areas in Curry, Josephine, and Jackson
Counties have seen a bit of a reduction in temperatures today
(relative to what they would have seen without the smoke aloft),
with high temperatures similar to yesterday`s. High-resolution
model guidance (the HRRR model) currently suggests that the
Rogue/Illinois Valley area will start to see some improvement in
terms of visibility and smoke this evening into tomorrow.
Further east, today will likely see the warmest temperatures of
the week, as ridging will start to break down and move eastwards
over the weekend into the early week as the Gulf of Alaska low
slowly spins its way onshore. This low will bring a weak cold
front through the region, passing through late Sunday, bringing
an increase in breezy winds to ridgetops across the region and
relative reduction in temperatures (approaching average daytime
temperatures for late July). There is a very slim chance for
precipitation in the far northwest corner of the region (less than
10%), but a much greater chance that any precipitation will be
well to the north of our area.
Following the passage of the low out of our area, models agree
that we`ll be in a general troughy pattern, with shortwave lows
riding down the broader trough. We`re expecting near to a scant
couple of degrees below normal temperatures for this time of year
as a result, though ensemble model members continue to suggest
that there will continue to be dry weather through the period.
-CSP
FIRE WEATHER...Updated 200 PM PDT Friday, July 21, 2023...We are
still looking at a dry end to the month with no precipitation in
the forecast for the foreseeable future. The one caveat is
Monday/Monday night when showers/thunderstorms may pass just to
the north of the forecast area. Overall, the general theme going
forward is hot, dry, and breezy afternoon/early evening winds.
Only slight fluctuations in the thermal trough are forecast through
the weekend and into early next week, and this should allow for
onshore flow (west winds) each afternoon in addition to breezy winds
in the afternoon and early evening. The onshore flow should help
moderate RH values slightly. However, we are generally expecting RH
values which could yield elevated fire weather conditions for a good
chunk of the area in the afternoons, especially for westside valleys
and east of the Cascades where values may actually be in/close to
critical thresholds. Wind speeds are going to be marginal, so the
key for us going forward is pinpointing those days when critical
values do overlap. Current thinking/analysis suggest Sunday could be
a good candidate for a Red Flag Warning. Critical conditions may
linger into Monday as well. -Guerrero
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 3 AM PDT Saturday
for PZZ356-376.
&&
$$
Area Forecast Discussion
National Weather Service Melbourne FL
858 PM EDT Fri Jul 21 2023
...New UPDATE, MARINE, AVIATION...
.UPDATE...
Issued at 854 PM EDT Fri Jul 21 2023
Convection overall today has been fairly limited, with isolated to
scattered showers and lightning storms forming along the east coast
sea breeze around mid afternoon, with a few storms forming around
the Orlando area by late afternoon. Coverage has increased across
the south this evening, around the Lake Okeechobee area from lake and
outflow boundary interactions. This activity is generally moving
eastward around 10 mph. Any lingering activity is expected to
dissipate or move offshore by 11 PM, with mostly dry conditions
forecast overnight. Hot and humid conditions continued this
afternoon, with many sites reaching peak heat index values ranging
from 105-109. Not much in the way of relief expected tonight, with
overnight lows in the mid to upper 70s. Forecast remains on track,
with only minor adjustments to rain chances this evening to account
for current storm coverage and updates in the models.
&&
.MARINE...
Issued at 854 PM EDT Fri Jul 21 2023
Current buoy 41009 observations show seas are 1 ft with S winds
around 12 KT. Offshore moving showers and storms will continue to be
possible this evening as diurnal convection dissipates. S/SW winds
will veer SW/W after midnight and increase to 10-15KT in the
offshore waters. Seas 2-3ft.
&&
.AVIATION...
(00Z TAFS)
Issued at 854 PM EDT Fri Jul 21 2023
VFR conditions outside of convection expected through the TAF
period. Scattered showers and storms ongoing this evening, mainly
across the Treasure Coast. This activity is expected to dissipate by
11pm, with dry conditions forecast overnight. W/SW flow this evening
become light overnight before increasing to around 10 KT by late
morning. Models show the east coast sea breeze forming, but
remaining pinned to or just offshore the coast, so have not included
a wind shift at this time. Have included VCTS starting at 19Z for
LEE, 20Z for MCO, SFB,ISM, and 21Z for all coastal sites.
&&
.PREVIOUS DISCUSSION...
Issued at 318 PM EDT Fri Jul 21 2023
Current-Tonight...Very limited coverage of showers and thunderstorms
as of 3pm, with only a few returns moving eastward out of Polk
County towards the Kissimmee River, and isolated pop up showers over
Okeechobee County. The east coast sea breeze has begun a journey
inland south of Cape Canaveral, nearly reaching I-95 in southern
Brevard and Indian River counties. As storm activity over the
interior continues the eastward progression over the next several
hours, additional activity is expected to develop along the outflow
and sea breeze collisions. The past several runs of the HRRR have
done a windshield wiper effect, pulling back significantly on storm
coverage but now returning to scattered to numerous storms from
Brevard County southward this evening. Moisture this afternoon has
increased slightly which may yield a higher coverage as well but if
previous day`s are any indication, activity may be sparse. Still,
any storms that do develop will be capable of producing wind gusts
up to 45 mph, frequent lightning and torrential downpours that could
lead to minor flooding.
In terms of the heat, many sites that have already seen a sea breeze
passage have reached a heat index of at least 107 to 108 degrees,
with all sites reporting above 102-103 this afternoon. Temps may
rise just a few degrees more, but should begin to taper back with
hopes of convection aiding in the evening cool down. A Heat Advisory
remains in effect for Indian River, Saint Lucie, Martin and
Okeechobee counties for a few more hours.
By sunset, highs in the mid 90s will retreat to the 80s, with lows
in the upper 70s. Storms will push towards the Space and Treasure
Coasts, dissipating soon after dusk.
Saturday-Sunday...The ridge axis draped across South FL today will
drag southward into the weekend as a mid level trough pulls down
from the Great Lakes. As the west wind regime remains solid, the
west coast sea breeze will again be favored with limited evidence
for the east coast sea breeze pushing inland. PWATs over 2.00" will
support convective development and slightly higher coverage than
today. Winds over 40-50 mph, lightning and heavy rain leading to
flooding will all be possible once again.
Similarly to today, temperatures will climb to the low to mid 90s
and a slight increase in moisture could up the max heat indices
above criteria levels, however further evaluation for a heat
advisory will be made at the next forecast package.
Sunday will hold more of the same (hot and stormy), with PoPs
climbing from 50% on Saturday to 50-70% on Sunday. Higher rain
chances open the potential for higher cloud cover and the
possibility for slightly lower highs just below 95 degrees. Will
still monitor dewpoints through the period which becomes the final
mark to evaluate in Heat Advisory situations.
Monday-Thursday... The mid level trough flattens out as high
pressure over the southern U.S. and Atlantic build back over
Florida. The ridge axis of the Atlantic high at the surface lifts
back north, switching flow from westerly/southwesterly early in
the week to easterly by mid week. High rain chances as PWATs
remain at or greater than 2.0", but could see some drier working
its ways across Florida mid week. Generally higher than normal
rain chances at 50-70 pct, but went ahead and capped PoPs later in
the forecast period due to increasing inconsistency between
models. Forecast continues to call for above normal daytime
temperatures, with highs in the low to mid 90s and peak afternoon
heat indices 100-105. Overnight lows close to normal in the mid
70s.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 94 76 92 / 10 50 20 70
MCO 78 95 78 93 / 10 50 10 70
MLB 77 96 77 94 / 20 50 10 50
VRB 76 96 75 95 / 20 50 10 40
LEE 77 93 77 91 / 10 50 20 70
SFB 79 96 78 94 / 10 50 10 70
ORL 79 95 78 93 / 10 50 10 70
FPR 76 96 75 95 / 30 50 10 40
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Watson/Pendergrast/Schaper
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 233 PM CDT Fri Jul 21 2023
Key Messages:
- 20% chance of showers/storm tonight into Saturday morning.
- Additional storm chances (20%) Saturday afternoon and evening.
Strong to isolated severe storms possible (5% chance), with
gusty winds and hail the primary threats.
- Turning hot and dry Sunday and beyond with highs mostly in the
90s, with heat index values 100-107 Tuesday through Friday.
Air temperatures could reach 98-102 on Thursday.
There will be a slight chance of showers and thunderstorms tonight
into Saturday morning, spreading from north to south, as a very
weak, subtle disturbance moves through the region. Latest runs of
the HRRR have even backed off on any activity in northeast NE
until 02-03z. And whatever develops then pushes south of I80 by
12z, and then continues southward Saturday morning into Saturday
afternoon. All of this activity is not expected to be severe. It
will be closer to normal for highs Saturday with readings in the
mid to upper 80s.
And then there could be scattered thunderstorm development across
central NE Saturday, which could clip southeast NE as well.The
weak impulse bringing thunderstorm activity across central NE
Saturday afternoon could bring continued isolated chances south of
I80 Saturday night. It`s these storms develop, they have a higher
chance of severe weather and the area is in a marginal risk of
from SPC. All of the weather would be over by daybreak Sunday.
And then it just gets hot and increasingly humidly. High temperatures
Sunday reach the upper 80s to lower 90s, but then mid to upper
90s for many areas for the rest of the week. Thursday could be the
hottest day with a forecast from 95 to 102. Dewpoints will become
increasingly muggy reaching the upper 60s to lower 70s, which
will create heat index values from 100 to 107 each day Tuesday
through Friday, and we may need heat advisories for those areas
that are expected to reach 105, especially Tuesday, Wednesday, and
Thursday. And yes it`s supposed to be hot in July, but given the
relatively mild July so far, the heat for the end of the month
will definitely become an issue. And it looks relatively dry
during this time as well. Looking farther ahead, both the 6-10 and
8-14 day outlooks call for a very high chance of above normal
temperatures too.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 620 PM CDT Fri Jul 21 2023
Expect a mostly quiet TAF period with VFR conditions prevailing.
After 08z there is a low-end threat for spotty showers and
thunderstorms through 13z, however confidence is too low to
include in the TAF. Expect light winds overnight which turn
northwesterly by Saturday afternoon.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...DeWald
AVIATION...Pearson
Area Forecast Discussion
National Weather Service Phoenix AZ
521 PM MST Fri Jul 21 2023
.UPDATE...Updated Aviation Discussion...
&&
.SYNOPSIS...
Historically hot and dry conditions will continue across the
region going into the weekend. Thunderstorm chances will increase,
first across higher terrain going into the weekend, and then
eventually across lower deserts by the end of the weekend and
extending into early next week. However, temperatures expected to
still remain well above normal going through the middle of next
week.
&&
.DISCUSSION...
The unending heat event continues, with temperatures again
spiking into the one-teens this afternoon. It is also a touch more
humid today as dew points are running about 5F ahead of
yesterday, thanks to a notable outflow/gulf surge/gravity wave
from a Sonoran MCS early this morning. Peak wind gusts in the Yuma
area were about 30-40 mph. Today does look like the peak of the
event though, with decreasing temperatures this weekend though
still elevated. EPS-based EFI MaxT values will drop from around
0.9 today to 0.6 on Monday. This, along with uncertainty regarding
convection (see following paragraphs) support the continued
action of the EHW/HTY ending across most areas tomorrow evening
followed by the Phoenix area Sunday evening. It is noted that KPHX
itself will still be very hot and landing in the "Extreme"
HeatRisk category much of next week, but spatial coverage across
the CWA and metro drop significantly Monday. It should also be
noted that impacts can and do still occur in the "Moderate"
HeatRisk category.
Today through Sunday, the H5 anticyclone will be weakening and
shifting east. In fact, H5 heights Saturday afternoon are forecast
to "only" be at the 90th percentile (GEFS/EPS). Meanwhile near
the surface, successive MCS activity across Sonora will pump
additional moisture northward into our CWA, with PWATs increasing
to around 1.2-1.5". These values are not unusually high/low for
late July, but the combination of increase BL moisture and lower
mid-level temperatures will mean an increase in instability.
Again, not exceptional values for late July, but enough to promote
increasing TS chances. For this afternoon, showers/storms will
likely remain confined to high terrain areas with a minimal (10%)
chance of seeing activity into nearby lower elevations. More
likely will be gusty outflow winds into the fringes of the Phoenix
metro, perhaps into the city. While HREF data were not suggesting
this, latest HRRR runs are noting it. A similar pattern appears
likely for Saturday with better potential (30%) for outflows and
even a minimal (<10%) signal for isolated severe winds. By Sunday,
steering flow will be adjusting enough to provide a more
favorable ESE to WNW direction and combined with instability
maximizing, we`ll have the best chance for broader convective
activity across mountains and deserts. Extended range UA-WRF CAMs
are suggesting the potential for significant outflow winds and
possibly damaging downbursts. Localized heavy rain can`t be ruled
out either, with WPC ERO carrying a marginal risk for Maricopa
County east.
After Sunday, global models suggest the H5 anticyclone will
strengthen a bit again, but the abnormally high heights will be to
our east. This should put Arizona roughly in the moist southerly
return flow on the upstream side of the ridge. Temperatures will
continue to be hot with persistent chances for mountains
showers/storms. Mitigating factors though would include slightly
increasing mid-level temperatures and a dry southwesterly flow
over California mixing in from the west.
&&
.AVIATION...Updated at 0015Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Ongoing storms north and east of the Phoenix metro late this
afternoon are expected to send outflows at least out of the north
early this evening reaching the terminals between 02-03Z. Wind
gusts of 20-30 kts will be possible before winds eventually turn
easterly mid evening. These easterly winds are then likely to
persist through Saturday morning before turning back to the west
with typical diurnal timing of around 17-19Z.
Southeast
California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected through Saturday morning. Winds
at IPL will maintain a westerly component this evening before
turning southeast tonight, while BLH will see persistent southerly
winds through the entire period. FEW mid and high level clouds
are anticipated over the course of the forecast period.
&&
.FIRE WEATHER...
An uptrend in thunderstorm activity is anticipated first across
higher terrain areas in southcentral AZ beginning today, and
eventually across lower desert areas from east to west through the
weekend. The most widespread impact from regional storm activity
through Saturday will be strong gusty winds. Storms will become
more capable of producing wetting rains early next week. As is
typical, precipitation chances will be primarily limited to areas
east of the Lower Colorado River Valley. Despite the influx of
moisture, well above normal temperatures will continue. Increasing
moisture across the region will result in an uptrend in RH`s with
overnight recoveries trending from poor to fair by the end of the
weekend. Apart from thunderstorm influences, winds will continue
to favor warm season patterns with long lived upvalley winds in
the afternoon and evenings with shorter lived downvalley patterns
in the late night and morning hours.
&&
.CLIMATE...
Record High Temperatures:
PHOENIX YUMA EL CENTRO
July 21 118 (2006) 118 (2006) 118 (2006)
July 22 116 (2006) 116 (2006) 119 (2006)
July 23 115 (2018) 117 (2014) 118 (2018)
July 24 116 (2018) 118 (2018) 121 (2018)
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Saturday for AZZ530>536-
538-539-545-547-552>556-559>562.
Excessive Heat Warning until 8 PM MST Sunday for AZZ537-540>544-
546-548>551.
Heat Advisory until 8 PM MST Saturday for AZZ557-558-563.
CA...Excessive Heat Warning until 8 PM PDT Saturday for CAZ560>570.
&&
$$
DISCUSSION...Iniguez
AVIATION...Kuhlman
FIRE WEATHER...Young
CLIMATE...Young
Area Forecast Discussion
National Weather Service Shreveport LA
846 PM CDT Fri Jul 21 2023
...New UPDATE...
.UPDATE...
Issued at 828 PM CDT Fri Jul 21 2023
Early update this evening to remove the Excessive Heat Warning and
Heat Advisory headlines from the ZFP. Prefrontal trough has pushed
south of the 1-20 Corridor late this evening but the true frontal
boundary is still further north near the Middle Red River Valley
of NE TX and SE OK into our far northern counties in SW AR attm.
Theta-E analysis showing the true frontal placement the best at
00z with the front forecast to move just north of the I-20
Corridor in NE TX to near the AR/LA border near midnight before
moving very slowly south of the corridor in NE TX to near the
corridor in N LA by sunrise Saturday Morning. Latest CAMS as well
as recent HRRR and 18z NAM output still insistent on scattered
convection developing later tonight just in the wake of the cold
front across SE OK and SW AR with this convection spreading south
and east into our far northern parishes in N LA north of the I-20
Corridor after midnight. Something a majority of these solutions
support is a weakening trend to the convection after sunrise
towards the I-20 Corridor before we should see renewed developing
with afternoon heating mainly south of the Corridor across Deep
East Texas into portions of West Central and East Central
Louisiana. With the evening update, tried to graphically portray
this trend in the pop and weather grids tonight through Saturday.
Concerning temperatures, did not make much in the way of changes
to overnight low temperatures but high temperatures in advance of
the front on Saturday across our southern third will be tricky.
All sorts of variables come into play which include convective
debris cloud cover, compressional warming in advance of the cold
front not to mention rain chances. Feel pretty certain that at
least another Heat Advisory will be necessary across our southern
third which would incorporate the Lower Toledo Bend and Sam
Rayburn Country of Deep East Texas into our southern parishes in
Northern Louisiana but without additional model data to look at,
will shift this decision to the next oncoming shift with a full
model suite to look at.
Updated forecast has been sent...13.
&&
.SHORT TERM...
(This evening through Saturday Night)
Issued at 210 PM CDT Fri Jul 21 2023
A weak frontal boundary across southern Arkansas into southeast
Oklahoma will drift south across the region through the short-term
period eventually settling just south of the ArkLaTex by Saturday
afternoon. As the front moves through the region overnight,
increased convergence will provide enough instability to support
broken ceilings by daybreak along with a few showers. Aloft, the
upper-level ridge will shift west allowing for northwest flow to
increase areawide. With more instability aloft, diurnally driven
storms are possible at the time of peak heating on Saturday,
mainly along and ahead of the front where dewpoint values are will
be in the 70s. Convection is forecast to linger into Saturday
evening, mainly south of I-20.
Some relief from the heat is expected across much of south
Arkansas, northeast Texas, and southeast Oklahoma as a cooler and
drier airmass builds behind the front. Afternoon high temperatures
on Saturday will range from the mid 80s across southwest Arkansas
and southeast Oklahoma to around 100 degrees south of the frontal
boundary across the lakes region of Deep East Texas. Further heat
headlines are expected across portions of Deep East Texas and
west-central Louisiana into Saturday. However, due to the
uncertainty of the frontal placement, will wait for the next
forecast cycle to pinpoint timing and placement of any heat
hazards for Saturday. /05/
&&
.LONG TERM...
(Sunday through next Thursday)
Issued at 210 PM CDT Fri Jul 21 2023
Sunday morning will see the upper-level heat ridge over the Four
Corners region with the core right at 594dam. Meanwhile, the
deepening Ohio River Valley trough will be running along a 588dam
contour over our I-49 corridor and all set to lift away the east
all too fast. And with that the heat ridge will be expanding back
over the midSouth into the new work week. Monday morning has the
upper ridge at 598dam over NM and lifting heights over head with
591 in the morning and back to a 594 contour overhead by sunset.
Thankfully, the core of the upper high will remain over NM building
a bit to 600dam and holding strength much of the last week of the
month. After more low to mid 90s on Sunday much of the new week will
be dealing with upper 90s on average and still likely advisory
criteria to finish off a very hot July. Morning lows will be rising
from near to below average to back well above average readings in
the mid to upper 70s during mid to late week.
As far as rainfall goes, coverage is looking rather sparse for us
with most of the action along the I-10 corridor early to midweek.
Another weak frontal boundary may be in play once again next
Saturday. To note, we are moving into our drier time of the year in
late summer and early fall. While quite varied from Tyler to Monroe,
Shreveport wedged in between is still sporting an 8 inch surplus for
the year, but that will erode as the drought monitor sees more
action than area radars for a while. The WPC QPF looks decent for
day one, but then falls off to near zero for the balance of the
month. /24/
&&
.AVIATION...
(18Z TAFS)
Issued at 1231 PM CDT Fri Jul 21 2023
A weak frontal boundary will move into northeast Texas and north
Louisiana overnight bringing MVFR ceilings to GGG/TXK/SHV/MLU/ELD
terminal sites by daybreak with gradual improvement throughout the
morning. However, ELD may hold MVFR ceilings through the end of
the TAF period at 22/18Z. In addition, showers may be possible
across the above mentioned terminals during the predawn hours.
Otherwise, VFR conditions to prevail areawide. NW winds up to 8
knots to prevail across SHV/MLU/TXK/ELD today with southwest winds
elsewhere. Light and variable winds expected tonight, becoming NE
up to 6 knots across most sites on Saturday. However, LFK may
remain under SW winds as frontal boundary lingers north of this
site./05/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 79 94 74 95 / 0 20 10 0
MLU 76 91 70 93 / 10 30 20 0
DEQ 71 88 67 90 / 40 30 0 0
TXK 74 89 70 92 / 50 40 0 0
ELD 72 86 66 91 / 50 50 0 0
TYR 78 96 73 95 / 0 10 0 0
GGG 78 95 73 94 / 0 20 10 0
LFK 78 102 75 97 / 0 30 20 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...05
LONG TERM....24
AVIATION...05