Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/23
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
556 PM MDT Sat Aug 5 2023
...New AVIATION...
.SYNOPSIS...
Issued at 252 PM MDT Sat Aug 5 2023
A strong to severe storm or two is possible in far northeastern New
Mexico this afternoon and evening. A backdoor front will push
through eastern New Mexico tonight and potentially create an east
canyon breeze in the gaps of the central mountain chain early
tomorrow morning. Near to record breaking heat is expected at least
the next seven days with triple digits in most lower elevation
locations. Breezy to windy westerly winds will create elevated to
locally critical fire weather conditions each day through Tuesday in
portions of north-central New Mexico. An increase in storm coverage
is possible in western and central areas mid to late next week
although confidence is low.
&&
.SHORT TERM...
(This evening through Sunday night)
Issued at 252 PM MDT Sat Aug 5 2023
A few storms have ignited over the higher terrain of Lincoln county
and have moved southeast into Chaves county. A boundary stretched
from near Raton through about Conchas Lake and the Tucumcari area
late this morning has moved little so far this afternoon. High based
cumulus was developing over the west central and southwest high
terrain as well as along the rest of the central mountain chain
where some gusty erratic winds are possible with any buildups. The
HRRR continues to suggest a couple of cells developing over Union
county later this afternoon, which is in a Severe Thunderstorm Watch
until 10 pm. A stronger boundary will push southward into northeast
NM later tonight, with slight chances for a light shower along the
Johnson Mesa/Raton Pass. Models indicate the boundary may reach the
east slopes of the central mountain chain early Sunday morning and
result in a relatively weak east wind into the Albuquerque Foothills
as well as at Santa Fe. The associated higher dewpoints look to
partially mix out from the west Sunday but models indicate another
reinforcing surge Sunday night. This will help moderate high
temperatures over portions of the northeast and east central, but
but the record may again be challenged at Roswell on Sunday. Dry and
gusty west winds are possible over portions of northwest and north
central NM Sunday afternoon, while gusty erratic winds will again
accompany any buildups over the west central into the south central
areas Sunday afternoon.
&&
.LONG TERM...
(Monday through Friday)
Issued at 252 PM MDT Sat Aug 5 2023
Breezy westerly winds to the north of an elongated ridge will keep
most of the state dry and suppress convection Monday afternoon
although a mix of dry and wet storms is possible in the southwest
where mid-level Pacific moisture will be on the rise. The ridge axis
slides southeastward on Tuesday and Wednesday, allowing more
elevated Pacific moisture to inch northward into the southwest
mountains. However, ensemble means are still only showing PWATs of
around 80-100% of normal so widespread precipitation is unlikely.
One feature to watch during this timeframe will be the tropical
depression that is currently located to the south of the Baja
Peninsula. Most guidance shows this feature getting directed by the
high pressure into southern California, but an eastward shift in the
track would correspond to an uptick in storm coverage during the mid
to late week timeframe.
Towards the end of the week, GEFS mean 500 mb heights show the
centroid of the high over south-central Texas whereas EPS members
show it further west over the Big Bend of Texas. If the high slides
further east as indicated by the GEFS solution, the region would
expect to see an increase in mid-level moisture and subsequent
uptick in storm coverage. The lack of low-level moisture would
inhibit widespread wetting rains, but the solution expressed by the
EPS wouldn`t even support much in the way of dry storms. Near to
record breaking high temps will continue throughout next week. An
increase in mid and high clouds associated with the elevated Pacific
moisture may keep highs down a few degrees but will provide little
in the way of relief from the scorching heat.
&&
.AVIATION...
(00Z TAFS)
Issued at 540 PM MDT Sat Aug 5 2023
Isolated showers and thunderstorms over eastern areas should
diminish with sunset, except for a few lingering cells over the
northeast corner of NM. A gusty, shallow and moist backdoor front
will dive into the eastern plains tonight. Behind the front,
areas of MVFR conditions are forecast as far south as KTCC through
much of Sunday morning. West and southwest winds look to become
gusty again Sunday afternoon mainly from the east slopes of the
Sangre de Cristo, Sandia, and Manzano Mountains westward. Isolated
showers and thunderstorms are forecast to return Sunday afternoon
from around Ruidoso and Elk north and northeastward to around Red
River, Raton, and Clayton. A few dry thunderstorms may also
develop over the southwest mountains. Dry and mostly dry
microbursts will be common Sunday afternoon with erratic wind
gusts potentially reaching 45 kt near storms and virga showers.
&&
.FIRE WEATHER...
Issued at 252 PM MDT Sat Aug 5 2023
...FIRE WEATHER WATCH REMAINS IN EFFECT MONDAY FOR NORTH CENTRAL NM
DUE TO DRY...HOT...WINDY...AND UNSTABLE CONDITIONS...
Dry westerly winds will lead to localized critical fire weather
conditions over northwest and north central NM Sunday. Stronger west
winds but continued dry weather will lead to more widespread
critical fire weather conditions Monday afternoon and evening, when
a Fire Weather Watch remains in effect. Critical conditions could
expand over a larger area of northern NM Tuesday, especially into
the Northwest Plateau. While the west central and central highlands
are not in the Monday Fire Weather Watch, there is potential for
isolated dry lightning in those areas Monday afternoon, as mid level
moisture increases leading to more widespread thunderstorm activity.
For the rest of next week, most of the west will see isolated to
scattered showers and storms as the stronger westerly flow relaxes,
but some of them will be drier with gusty winds. Overnight humidity
recoveries will be mostly fair to poor and temperatures will
generally be warmer than normal.
Over eastern NM, low level moisture will slosh back and forth
tonight through Sunday night. Any storms will be very hit and miss
but will have better potential for wetting rain through Monday
night. Tuesday through Friday may see few if any storms, then
chances may increase Saturday with a frontal boundary. Similar to
western NM, temperatures will be warmer than normal, although
overnight humidity recoveries will good closer to the TX border.
&&
.PRELIMINARY POINT TEMPS/POPS...
Farmington...................... 97 57 96 56 / 0 0 0 0
Dulce........................... 92 48 91 45 / 0 0 0 0
Cuba............................ 93 55 92 55 / 0 0 0 5
Gallup.......................... 94 51 94 55 / 0 0 0 0
El Morro........................ 90 53 90 56 / 0 0 0 5
Grants.......................... 94 50 94 56 / 0 0 0 5
Quemado......................... 93 58 92 58 / 5 10 10 10
Magdalena....................... 95 65 94 65 / 5 10 20 10
Datil........................... 92 60 91 59 / 5 10 10 10
Reserve......................... 98 59 96 58 / 5 5 10 5
Glenwood........................ 102 63 98 65 / 0 0 5 5
Chama........................... 86 47 85 44 / 0 0 0 0
Los Alamos...................... 91 62 91 61 / 0 0 10 5
Pecos........................... 93 59 90 58 / 0 0 10 10
Cerro/Questa.................... 89 48 86 46 / 0 0 10 5
Red River....................... 85 43 81 43 / 0 0 10 10
Angel Fire...................... 83 38 80 38 / 0 0 10 10
Taos............................ 93 52 90 51 / 0 0 5 5
Mora............................ 89 51 86 51 / 0 0 20 10
Espanola........................ 99 55 95 55 / 0 0 5 5
Santa Fe........................ 93 62 92 61 / 0 0 10 10
Santa Fe Airport................ 96 60 95 59 / 0 0 5 5
Albuquerque Foothills........... 98 70 96 69 / 0 0 0 5
Albuquerque Heights............. 100 70 100 71 / 0 0 0 5
Albuquerque Valley.............. 103 63 101 64 / 0 0 0 5
Albuquerque West Mesa........... 101 69 99 68 / 0 0 0 5
Belen........................... 104 65 102 70 / 0 5 0 5
Bernalillo...................... 103 65 100 65 / 0 0 0 5
Bosque Farms.................... 102 62 101 66 / 0 0 0 5
Corrales........................ 103 67 100 67 / 0 0 0 5
Los Lunas....................... 102 63 101 69 / 0 5 0 5
Placitas........................ 99 66 97 66 / 0 0 0 5
Rio Rancho...................... 101 68 98 67 / 0 0 0 5
Socorro......................... 104 68 101 72 / 0 5 5 10
Sandia Park/Cedar Crest......... 93 62 91 63 / 0 0 5 10
Tijeras......................... 97 65 94 65 / 0 0 5 10
Edgewood........................ 97 61 93 62 / 0 0 5 10
Moriarty/Estancia............... 96 58 94 58 / 0 0 5 10
Clines Corners.................. 94 59 90 59 / 0 5 10 10
Mountainair..................... 96 63 93 64 / 0 0 5 10
Gran Quivira.................... 96 64 94 65 / 0 5 10 20
Carrizozo....................... 99 70 99 70 / 5 10 10 20
Ruidoso......................... 91 63 89 63 / 20 20 20 20
Capulin......................... 89 54 80 54 / 20 30 30 30
Raton........................... 92 55 85 54 / 10 20 30 20
Springer........................ 97 55 89 55 / 10 10 20 20
Las Vegas....................... 94 55 89 55 / 0 5 20 10
Clayton......................... 95 61 85 59 / 20 30 20 30
Roy............................. 97 59 86 58 / 10 10 20 20
Conchas......................... 103 65 93 64 / 20 10 10 20
Santa Rosa...................... 100 66 94 65 / 10 10 10 20
Tucumcari....................... 106 67 93 66 / 20 20 10 20
Clovis.......................... 102 67 94 68 / 20 20 0 20
Portales........................ 104 69 97 69 / 20 20 0 10
Fort Sumner..................... 103 69 98 69 / 20 20 5 10
Roswell......................... 109 75 104 74 / 10 10 5 10
Picacho......................... 99 69 96 69 / 20 20 10 10
Elk............................. 95 66 92 65 / 20 20 20 10
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM MDT this evening for NMZ219-220-234-238.
Heat Advisory from noon to 7 PM MDT Sunday for NMZ219.
Fire Weather Watch from Monday morning through Monday evening
for NMZ120>123.
&&
$$
SHORT TERM...99
LONG TERM....16
AVIATION...44
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
642 PM CDT Sat Aug 5 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Sunday night)
Issued at 230 PM CDT Sat Aug 5 2023
Inherited forecast tracking very well. Very hot and rain-free
conditions continue. Water-vapor satellite and RAP analysis show
rather dry air aloft associated with subtropical high. Axis of high
at 500mb stretches roughly along 30N latitude, sparing us slightly
the brunt of the heat...but that`s about it. SPS for elevated heat
indices also on-target. 12Z BRO sounding indicated Td in mixed-
layer ~73F, which is borne out in current obs. Even with a slight
bump up behind the sea-breeze, not expecting more than an hour or
two of heat indices in the 111-113F range later in the afternoon.
Only subtle changes in the pattern occur for tomorrow, but they will
only make it feel worse. Center of high aloft moves little, but is
progged to strengthen slightly, with local 1000-500mb thicknesses
nudging up by 1 dam or so, which should all but ensure another 100F
high for Brownsville. Concurrently, model time-heights show higher
RH in the boundary layer on Sunday vs. today. This appears to be
associated with a the passage of a weak inverted trough well to our
south, and the slug of slightly higher PW values (not enough for
rain, though!) is currently analyzed to our SE over the Gulf. The
slight addition of heat and less mix-out of dewpoints (2-3F higher
vs. today for the afternoon in the populated RGV) should put much of
the area into a Heat Advisory. Not as confident on Jim Hogg and
Zapata counties, though, so will leave them out for now. Sunday
night, column RH crashes again, but still leaves us with another
sultry night with Monday morning low temps in the upper 70s to near
80F.
&&
.LONG TERM...
(Monday through next Saturday)
Issued at 230 PM CDT Sat Aug 5 2023
Key Messages:
-Dangerous Heat to continue with Heat Advisories expected
through the week.
-Dry conditions remain, with the only rain chances on the offshore
Gulf waters.
High pressure will remain in place through the long term period,
meaning the hot and dry weather will continue. Temperatures are
expected to remain above normal, with highs generally in the 100s,
with 90s along the coast. Will certainly have to keep an eye out
for more record breaking temperatures through the week. Elevated
dewpoints could warrant Heat Advisory conditions for at least some
portion of the CWA each afternoon. An Excessive Heat Advisory can
no be ruled out, primarily for Wednesday and Thursday as
temperatures and dewpoints combine to make "feel like"
temperatures potentially reach 116+ degrees for 2 or more hours.
Continue to practice heat safety each day, especially if spending
time outdoors. Overnight temperatures will likely remain near to
just above normal for the overnights as well.
Winds will pick up each afternoon and the thermal gradient
tightens, with the windiest days expected Tuesday through
Thursday. The gustier conditions midweek could lead to the
potential for erratic wildfire spread, see more about that below.
Unfortunately, no rain is in sight, except some stray streamer
showers over the offshore Gulf waters.
&&
.AVIATION...
(00Z TAFS)
Issued at 637 PM CDT Sat Aug 5 2023
VFR conditions are expected to continue throughout
the TAF period. Wind gusts are expected to diminish this evening
after sunset with winds remaining southeasterly overnight. Gusts
pick back up late tomorrow morning.
&&
.MARINE...
Issued at 230 PM CDT Sat Aug 5 2023
Now through Sunday Night...Small Craft Exercise Caution
conditions currently in effect for the Laguna Madre for SE winds
of 15-20 knots and choppy bay conditions. This is likely to repeat
on Sunday from late morning through early evening as thermal
gradient along the coast re-intensifies. Otherwise, fairly
pleasant marine conditions persist on the Gulf, with winds of
10-15 knots and seas running 2-3 ft.
Monday through Friday...Moderate winds will lead to the
potential for Small Craft Caution, especially across the nearshore
Gulf waters and the Laguna Madre, through the period, due to
elevated winds. With a stronger pressure gradient on Tuesday and
Wednesday, winds could increase enough to warrant a Small Craft
Advisory on the Laguna Madre and nearshore Gulf waters. Wave heights
will generally remain in the 3 to 4 foot range with 5 to 6 second
periods.
&&
.FIRE WEATHER...
Issued at 230 PM CDT Sat Aug 5 2023
A Fire Danger Statement remains in effect until 7 PM
CDT for all but the coastal and barrier island zones. Widespread
dry fuels are present, with critically dry fuels in the mid/Upper
RGV, per latest rating from Texas A&M Forest Service. With better
mixing today, a few gusts have reached 30+ mph in Cameron County,
but RH`s remain 40-45% there. RH`s have fallen to 25-30% in
Hebbronville and Zapata, but winds are much lighter. With no change
in fuel state, and only very slightly higher RH`s forecast for
Sunday, another Fire Danger Statement is likely.
As we head into the work week potential Fire Danger Statements may
be needed. Humidity levels will continue to be low each afternoon
and the thermal gradient will cause winds to increase. These
factors combined with the dry to critically dry fuels across the
region, will lead to a greater concern for wildfire spread. Fire
Danger Statements will be possible, especially midweek.
&&
.CLIMATE...
Issued at 230 PM CDT Sat Aug 5 2023
As of 2pm CDT, Brownsville has tied another daily record
of 99F (last set in 1999), and may yet eclipse it before the day is
done. For Sunday, Brownsville`s record high is 100, which is
currently forecast to be tied. Harlingen International Airport`s
record high is a somewhat surprisingly low 101F for 06 Aug. Forecast
high is 103F, which would break the record.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 82 100 81 98 / 0 0 0 0
HARLINGEN 78 102 78 101 / 0 0 0 0
MCALLEN 80 104 79 103 / 0 0 0 0
RIO GRANDE CITY 79 107 77 106 / 0 0 0 0
SOUTH PADRE ISLAND 82 91 82 90 / 0 0 0 0
BAYVIEW/PORT ISABEL 80 97 80 98 / 0 0 0 0
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory from 1 PM to 7 PM CDT Sunday for TXZ250>255-351-
353>355.
GM...None.
&&
$$
SHORT TERM...53-Schroeder
LONG TERM....68-McGinnis
AVIATION...60-BE
Area Forecast Discussion
National Weather Service Cheyenne WY
609 PM MDT Sat Aug 5 2023
.SHORT TERM...(Tonight - Monday Night)
Issued at 244 PM MDT Sat Aug 5 2023
A strong, fall-like cold front is pushing southward across the CWA
this afternoon. This frontal zone was analyzed roughly along the I
80 corridor at 20z, and should exit into northern Colorado shortly
w/ mainly dry northwesterly winds gusting 30-40 MPH across much of
southeast Wyoming in its wake. Until this occurs, there could be a
small potential for isolated thunderstorms near the Colorado state
line through late afternoon in response to enhanced convergence on
the leading edge of the frontal zone. Despite the presence of west
winds at the surface, up to 1000 J/kg MLCAPE and 30 to 40 knots of
effective bulk shear along/south of I-80 from the southern Laramie
Range to Sidney will be sufficient for any potential storms to get
fairly strong to marginally severe as dew points remain the middle
40s to lower 50s. Main focus for convection today though should be
Carbon/Albany counties as some additional mid-level energy quickly
pivots around the main short wave over the Dakotas. Showers/storms
could become quite numerous this evening over these areas, and may
contain heavy rainfall as well as some hail/wind potential as bulk
shear should increase to 30-40 knots over the next few hours given
the stronger flow associated w/ the next disturbance. Also appears
the latest RAP does keep a ribbon of 500 J/kg of MLCAPE which does
extend back into Carbon County through late evening. Some CAMS are
remaining consistent w/ this area becoming a hot spot later today,
especially after 00z, so have increased PoPs considerably.
700-mb temperatures will plunge to +6 to +8 deg C by early Sunday,
helping to limit daytime highs to the lower 70s and forcing night-
time lows into the 40s over the next 24-36 hours. Showers & storms
may become quite numerous on Sunday afternoon & evening w/ diurnal
heating and seasonably cool temperatures aloft contributing to the
presence of appreciable instability. Severe potential should be on
the low side given fairly weak CAPEs. Unsettled weather will carry
over into Monday beneath active zonal flow aloft w/ numerous short
wave disturbances embedded within the flow.
.LONG TERM...(Tuesday - Saturday)
Issued at 244 PM MDT Sat Aug 5 2023
No major changes were made with this forecast update. The weather
pattern looks generally a little quieter than recent weeks, but
periodic chances for afternoon showers and thunderstorms will still
be in the forecast several days during the week ahead.
Picking up on Tuesday, we`ll have the subtropical ridge flattened a
little bit to the south with northwest flow over our area. A potent
vort-max or small closed upper level low will dive over the northern
Rockies on Tuesday and traverse across northern Wyoming. This will
help to keep temperatures on the cool side, especially for the
northern tier, and also kick up the winds and precipitation chances.
Look for a breezy to windy day especially west of I-25 as the flow
aloft climbs slightly ahead of the approaching shortwave. There
should be enough moisture left to support scattered showers and
thunderstorms Tuesday afternoon, though convective parameters look
fairly limited for severe weather at this time. Still will bear
watching as it approaches.
This wave is expected to depart by early Wednesday, and we may
manage a few dry days across the area! We`ll have a flattened ridge
to our south for Wednesday and Thursday with PW values likely to
drop below normal, and westerly breeziness continuing at the
surface. Wednesday looks rather dry compared to recent weeks, with
only a few ensemble members showing any precipitation at all across
the area. The ECMWF ensemble gets slightly wetter Thursday, but most
of the GEFS members are totally dry. Kept dry PoPs in for Wednesday,
but did keep a low end slight chance in for the higher terrain on
Thursday since models have been running too dry recently. The core
of the ridge should be away from our area, so not really looking at
much heat, but high temperatures should return to normal. Ensembles
show 700-mb temperatures recovering fairly quickly from Tuesday`s
shortwave, reaching back to around +13 to +15C by 00z Thursday and
holding fairly steady after that. Thursday looks like the warmest
day of the week with some warm air advection ahead of another upper
level low passing to our north. For the end of the week, the ridge
amplifies and moves ever so slightly eastward while a low moves
closer to the California coast. This may initiate another surge of
monsoon moisture, but most ensembles are showing this as fairly
modest, at least compared to the last surge.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 608 PM MDT Sat Aug 5 2023
A storm system located to the northeast in South Dakota could bring
some MVFR CIGs to KCDR and KAIA this evening. KCDR has been bouncing
between VFR and MVFR and expect this to continue over the next
several hours. Along with this storm system, blustery north winds
with gusts over 30 kts will be possible throughout the evening
hours. For southeast Wyoming terminals, scattered showers and
thunderstorms will be possible this evening and later tonight.
Conditions across the area improve overnight, leading to VFR
conditions by Sunday morning.
&&
.FIRE WEATHER...
Issued at 152 AM MDT Sat Aug 5 2023
Several days of wetting rains will keep fire weather concerns low
with lingering showers and thunderstorms remaining in the forecast
throughout the weekend. Cooler temperatures will also be expected
so minimum relative humidities will remain well above critical
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...CLH
LONG TERM...MN
AVIATION...SF
FIRE WEATHER...AW
Area Forecast Discussion
National Weather Service Dodge City KS
952 PM CDT Sat Aug 5 2023
...Updated Mesoscale...
.MESOSCALE DISCUSSION...
Issued at 952 PM CDT Sat Aug 5 2023
Complicated convection evolution continues. Storms near LaCrosse
appear to be the beginning of an MCS that will impact central
Kansas over the next few hours. Convection has so far struggled
over the core of the DDC CWA this evening, presumably due to the
capping inversion, with severe reports bypassing the DDC CWA to
the northeast and southwest. The rest of tonight will be dependent
on the evolution of eastern Colorado convection, which continues
to regenerate as of 950 pm CDT. These storms are developing along
and ahead of the synoptic cold front, which is progged to clear SW
KS around sunrise Sunday. Until that time, additional rounds of
thunderstorms are expected, some producing severe wind/hail and
some with locally heavy rain. 00z NAM has picked up on this trend,
with MCS generation over the DDC CWA 1-4 am Sunday. Now that we
are entering the core of the nocturnal hours, high end hail and
wind becomes much more unlikely, but marginally severe wind to 60
mph and quarter size hail are probable from stronger storms.
&&
.UPDATE...
Issued at 819 PM CDT Sat Aug 5 2023
Thunderstorm evolution remains challenging for the remainder of
the short term through tonight. As of 8 pm, infrared satellite and
radar imagery showed a loosely organized convective complex
entering north central Kansas. These storms will pose a risk for
marginally severe wind/hail along the I-70 corridor over the next
few hours. A strong supercell west of Elkhart in northern Cimarron
county, Oklahoma will remain out of Kansas. In between, convective
inhibition has kept a lid on development thus far. 00z HRRR
suggests storms will become more numerous, especially south of
US 50, towards and especially after midnight as the low level jet
incites elevated development. Will maintain high pops in the
current forecast through tonight, based on continuity, a moist,
unstable sheared environment, and the expected cold front passage
overnight. The later in the night the storms occur, the risk of
severity diminishes and transitions to locally heavy rain. Models
remain in agreement with the current forecast that the cold front
will clear all of SW KS by sunrise Sunday, with northwest winds
for all zones. Northwest winds will gust 20-30 mph with noticeably
cooler air Sunday.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 1219 PM CDT Sat Aug 5 2023
.Key Messages
- High confidence in severe weather across southwest Kansas
tonight
- Main threat will be large hail (> 2 inches in diameter) for
areas along the Colorado border and strong downburst winds (70+
mph) for much of southwest Kansas
- Another overnight round of storms is increasing in forecast
confidence for Sunday night
Noon observations show a departing line of thunderstorms in
northern Oklahoma with residual cloud cover in Barber and Pratt
counties. Elsewhere mostly sunny to partly cloudy skies are
allowing the insolation to help to destabilize the atmosphere
particularly in eastern Colorado. CAPE values over 1500 J/kg are
present with forecast of up to 3000 J/kg by storm initiation this
afternoon in the front range. Low level winds out of the east to
southeast will aid in upslope flow. Upper level winds show a
shortwave along the left exit region of a jet in the central
portions of Colorado where the expected initiation of the
thunderstorms will be which will lead to our overnight event.
Tonight the CAM models are in good agreement of a mixture of
supercells and linear storms coming into southwest Kansas around 7
PM and sweeping across the region through 1-2 AM Sunday morning.
Hodographs are showing veering aloft with a linear hodograph in
the upper levels which would indicate a good environment to
produce supercells and large hail especially along the Colorado
border. We`ve stuck with the earlier messaging about the risk and
timing with the storms as the SPC enhanced risk didn`t change from
the morning to the 1630Z update. One wild card to the storm
timing and risk is the outflow boundary along the I-70 corridor
which could produce some storms earlier than the 7PM timeframe as
well as residual outflow boundaries from the morning storms in our
southeast zone. Confidence in storm development and timing is low
in these scenarios.
Sunday should be noticeably cooler as the storms will exit along
a cold front and winds through the boundary layer will be north to
northwest. 850 mb temperatures will range from 18-20 (C) and high
should reach into the mid 80s.
Sunday night another large scale shortwave should move across the
Colorado Rockies and with easterly winds on the southwest side of
a high pressure center this will lead to upslope flow.
Thunderstorms should break out around the Denver metro in the late
afternoon and then move across western Kansas mainly during the
overnight hours (after midnight for most locations). Severe threat
at this point is low as most of the storms should be coming during
the night that most of the energy from the heat of the day should
have subsided and the 850 mb winds should be light which will
negate lower level shear. Lows should fall into the low to mid
60s.
.LONG TERM...(Monday through Saturday)
Issued at 150 PM CDT Sat Aug 5 2023
.Key Messages
-Good chances of storms (>40%) with heavy rain potential Monday
night and Tuesday morning
-Seasonal temperatures during the week (climatological high is
lower 90s)
Ensemble trends in the upper levels show continued stronger
westerly winds through the central portions of the country which
will keep the strong 597 dm high shifted to the south in Texas and
New Mexico. This should keep the core of the hottest air out of
the areas as temperatures will modestly rise during the week to
the mid 90s for highs by Thursday. With this weather pattern this
will also keep rain chances in the forecast for much of the week
with the main mode of storms being overnight MCS events.
Ensembles are hinting at a QPF hit for Monday night into Tuesday
morning where 0.5 to 1 inch of rain is possible with the overnight
MCS event moving across southwest Kansas. The setup will be
boundary layer winds out of the southeast producing upslope flow
in the Colorado rockies combining with a shortwave in the
westerlies which will trigger convection in the front range in the
late afternoon. Widespread thunderstorms are forecast to move
across southwest Kansas but the location of where the storms is
going to go over is still low confidence as some long term models
have the northern part of the CWA getting hit and some in the
southwest zones. Severe weather potential should be limited to
areas along the Colorado border where residual daytime heating
could lead to higher instability. Long term models are also
hinting at a similar setup Tuesday night into Wednesday morning
for areas more along the I-70 corridor and north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 428 PM CDT Sat Aug 5 2023
Aviation operations are expected to be impacted by thunderstorms
during the first half of this TAF period. Using the 12z ARW as a
guide, maintained convective TEMPO groups for all airports, during
the 01-06z Sun time range. Some storms will be severe, with
outflow winds near or exceeding 50 kts, and included this
potential in the TAFs. Flight category reductions will be brief,
with VFR quickly returning behind the expected MCS. Models do not
suggest any stratus potential in the post-frontal/MCS environment,
so did not include, but will monitor. Broken midlevel clouds
after the storms will clear to SKC daylight Sunday with strong
subsidence. Winds will trend north behind the thunderstorms. After
18z Sun, NW winds will increase at all airports, gusting
28-32 kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 63 85 61 83 / 80 0 40 10
GCK 60 81 60 82 / 80 0 60 10
EHA 61 85 61 87 / 60 0 40 10
LBL 63 84 63 85 / 80 0 50 10
HYS 63 84 60 83 / 50 10 10 10
P28 67 88 65 85 / 80 10 40 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Turner
UPDATE...Turner
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Turner
Area Forecast Discussion
National Weather Service Grand Forks ND
958 PM CDT Sat Aug 5 2023
.UPDATE...
Issued at 958 PM CDT Sat Aug 5 2023
Thunderstorm activity is rapidly diminishing as instability
decreases this evening. Showers are expected to continue
overnight, with rainfall possibly moderate to heavy at times.
Additional areas of flooding are possible, primarily in urban
areas and low-lying spots. The Fargo-Moorhead metro has seen some
of the highest rainfall totals of the evening, with 2-3 inches
reported.
UPDATE Issued at 659 PM CDT Sat Aug 5 2023
Upper low continues to move east-southeast this evening. Showers
and embedded thunderstorms are forming, generally in waves, in
areas to the east of the Red River, with more stratiform activity
to the west. Some of the updrafts have been strong enough to
produce funnel clouds as low-level vorticity is rather high. This
threat will diminish through the evening.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 341 PM CDT Sat Aug 5 2023
-Rain showers with embedded (scattered) thunderstorms are on track
to overspread southeast ND and west central MN through the evening
hours/overnight transitioning southeast through Sunday. Lightning
will be the main threat, and severe thunderstorms are not
anticipated. A few stronger storms capable of small hail and gusts
to 40 mph will still be possible.
-Localized heavy rain may lead to excessive runoff if rates are high
enough (3"+/hr), particularly in locations near the SD border where
earlier thunderstorm activity occurs. The probability for higher
rates is low in all by our far south (south of I-94), with
probabilities shifting towards SD/southern MN for 2"+ totals.
The main mid level circulation is deepening over central SD in line
with the southerly track that had been favored on ensemble/forecast
trends in the last 24hr. As a result the strongest signal for broad
heavier rain has shifted south. We are seeing broad areas of
moderate rainfall with embedded thunderstorms filling in the
northern side of this circulation along the warm conveyor belt and
eventually this should move into the I-94/US10 corridor early this
evening. Elevated instability in the RAP is 1000+ J/KG but
skinnier profiles are favored and cloud cover would limit surface
based convection. As a result even the strongest updrafts will
mainly favor heavy rain/smaller hail and max gusts to 40 mph.
Still, with at least some potential for training within these
heavier rain pockets there is potential for 1-3"/hr rates. Over
dry soils we would likely need 4-5"/hr rates for flash flooding,
but preconditioned locations could support excessive runoff if 3"+
rainfall fell over 6hr (mainly near the SD border).
Additional storms are forming near the cold front as an inverted
trough is beginning to form ahead of the norther wave/mid level jet
in Canada. The interaction of these features is still highlighted by
CAMs to resulting in organized deformation in our east-southeast late
this evening into the overnight/early morning hours with broad light
to moderate rainfall. HREF probs show 90%+ probs for 0.01" per hour
during those periods while blended ensemble 12hr probs for 0.1"+ are
60-80%. The probability for 0.5" and 1.0"+ 6hr probs drops off
quickly (main to the south of I-94) and for those values
thunderstorm activity would likely need to occur farther north).
THe entire deformation area of rain should decrease in intensity
and transition southeast through Sunday morning, with dry
conditions arriving by midday based on current timing/consensus.
.LONG TERM...(Monday through Saturday)
Issued at 341 PM CDT Sat Aug 5 2023
-The pattern will support low probabilities for showers or
thunderstorms, with the probability for hazardous weather low through
the long term periods.
-Temperatures will tend to remain near seasonal normals early in the
week, with below average temperatures (by 5-10F) favored late next
week into next weekend.
Large scale mid/upper level pattern will tend to be dominated by
relatively flat NW zonal flow in our region as a result of broad
ridging in the southwest US and a more elongated Hudson Bay low in
Canada. There is variance in the strength and exact position of those
upper level features, but the main impact on the pattern locally
between the various clusters is on the timing/track of progressive
weak mid level shortwaves. Due to the flow and limited southerly
return before each cold front (and tendency for moisture return to
be from drier parts of Canada) the potential for wetting
precipitation (0.1") and instability will be low with each of these
waves and associated fropas. As a result there isn`t a signal for
severe potential in NBM CWASP or GEFS based machine learning from
CSU.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 634 PM CDT Sat Aug 5 2023
MVFR conditions are possible tonight as showers and embedded
thunderstorms move across the area. An upper low will pass to our
south overnight and into Sunday morning, which will gradually
shift the winds more out of the north. As this happens, showers
will be winding down in coverage, with slow improvements in
ceilings. Visibility is expected to remain 5SM or higher,
especially outside of heavier shower activity. VFR conditions
develop by mid-morning Sunday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Lynch
SHORT TERM...DJR
LONG TERM...DJR
AVIATION...Lynch
Area Forecast Discussion
National Weather Service Goodland KS
929 PM MDT Sat Aug 5 2023
.UPDATE...
Issued at 921 PM MDT Sat Aug 5 2023
Due to the main round of storm activity moving east of the
forecast area, decided to cancel the northern half of the watch
area. Am keeping the southern counties in the watch for two
reasons: the current thunderstorm activity over Cheyenne County
CO, and the potential for elevated thunderstorm activity in
the near future.
Model guidance and radar trends continue to show the potential for
strong to severe elevated thunderstorms forming along the nose of
the LLJ behind the incoming cold front. (The cold front is
entering the northern part of the forecast area currently.)
Soundings show elevated CAPE around 1200 j/kg with 20-50 j/kg of
CINH. This is a similar setup to last night, only with the LLJ
coming in from the north instead of the south. Am thinking the
northern half of the forecast area is out of the threat due to the
stable environment behind the storm activity based on the lack of
cloud cover behind the recent storms. In addition isentropic lift
is over the southern half of the forecast area where the LLJ nose
will be in the near future. This activity should move south of the
forecast area by 2 AM MT. Confidence is moderate for another round
of severe thunderstorms to occur.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 310 PM MDT Sat Aug 5 2023
Active weather is expected during the late afternoon through
midnight tonight. As of 2 PM MDT, storms were developing along a
convergence zone over the Palmer Divide moving east to east-
southeast. The linear cluster of storms is expected to move into the
Flagler area around 3 PM MDT and into Cheyenne County, Colorado
between 4-5 PM MDT. The HRRR and NAMNest have been the more
aggressive/representative CAMs so far today. They are both depicting
the linear clusters/MCS to move east-southeast across the Tri-State
Area this evening Initially all modes of severe weather will be
possible, mainly along and west of the Colorado border. Tornadoes
have been observed over the Palmer Divide and will remain a possible
hazard for our Colorado counties at least through sunset though
confidence is medium at best. As the evening progresses and the MCS
really takes shape over Northwest Kansas, the main threats will be
large to giant hail, damaging winds, and heavy rain with potential
for flash flooding.
Despite the earlier convection this morning, the atmosphere is very
favorable for severe storms with 1,000-3,000 J/kg of CAPE, 1,000-
1500 J/kg of DCAPE, and high PWs. The cold front will be nudging
south over the Tri-State are tonight helping the storms as they move
through. There is also potential for localized blowing dust in areas
that have not received much rainfall lately. On the other hand, the
areas that received quite a bit of rainfall over the last few days
(mainly north of I-70) could have the flash flooding concerns. The
storms are expected to exit the area by midnight with some lingering
showers possible through the early morning hours. Overnight lows are
expected to be in the mid 50s to lower 60s.
Tomorrow the cut-off low aloft is expected to move across the
Central Plains towards the Mississippi River Basin while the upper
ridge strengthens over the Southwest CONUS to the Central High
Plains. This will keep the area dry through the mid afternoon. High
temperatures are expected to be in the upper 70s to mid 80s
tomorrow. During the mid to late afternoon hours, showers and storms
will be possible mainly over the western half of the area as we go
under northwest to north-northwest flow aloft. Severe weather is not
anticipated at this time; however, gusts up to 60 mph and small hail
are possible. Overnight lows will be in the mid to upper 50s.
.LONG TERM...(Monday through Saturday)
Issued at 338 PM MDT Sat Aug 5 2023
The Tri-State area will be under northwest flow aloft as the upper
ridge remains over the Southwest CONUS and Southern Plains mainly.
Another cut-off low is expected to sweep across the Rockies into the
Central Plains late Tuesday into Wednesday. As the low approaches,
multiple shortwave disturbances are expected to travel along the
ridge over the area leading to chances for afternoon/evening showers
and storms Monday and Tuesday. As the upper trough swings through,
precipitation chances will continue into Wednesday morning. Once the
trough exits, the area is expected to remain dry through the night.
More waves are expected to move across the Western CONUS during the
latter half of the week as an area of low pressure swings over
Southwest Canada. This will bring more shower and storm chances each
afternoon and evening, though confidence is lower with the chances
on Thursday evening should the ridge linger a bit longer over the
Tri-State area.
Temperatures are expected to remain cool on Monday with highs in
the upper 70s to lower 80s. Mid-week begins another slight warming
period with highs in the 80s on Tuesday and Wednesday. Thursday
through Saturday high temperatures are expected to warm into the
upper 80s to lower 90s. Overnight lows are expected to be in the
mid 50s to lower 60s Monday through Thursday and Saturday nights
and in the low to mid 60s Friday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 545 PM MDT Sat Aug 5 2023
VFR to IFR conditions forecast for the TAFs. The main focus is
timing the thunderstorm activity for both sites this evening. So
far KMCK looks to be the one to be most impacted by the storm
activity. Like last night, visibility could fall to IFR due to the
heavy rainfall. In addition, there could be strong to severe wind
gusts with any storms that move through. After the storm activity
the cold front will move through. Surface observations directly
behind the front show breezy north winds; so am expecting that to
be the case as it moves through. There could also be strong to
severe thunderstorms behind the front around 6z. Confidence at
this time is on the low side this will occur.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...KMK
LONG TERM...KMK
AVIATION...JTL
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
732 PM CDT Sat Aug 5 2023
.SYNOPSIS...
Issued at 726 PM CDT Sat Aug 5 2023
Severe thunderstorms are possible this afternoon in the vicinity
of I-57 and east across central IL. Shower and thunderstorm
activity will diminish this evening, but is expected to return on
Sunday. The best chance for severe thunderstorms on Sunday appears
to be from late afternoon in west-central IL to late evening
across east-central IL. An active pattern is expected for the
upcoming week, with temperatures a bit cooler than average.
&&
.UPDATE...
Issued at 732 PM CDT Sat Aug 5 2023
The impressive MCV from Missouri last evening has now crossed
Illinois and is located just north of Danville early this evening.
A little bit of drizzle/light showers have been observed along an
associated trough just south of I-72 to near Taylorville, but the
bulk of the rain is now off in Indiana. The latest HRRR model
only slowly lifts this MCV northeast, so some scattered showers
will remain possible through midnight mainly near Champaign and
Danville. While some clearing has taken place northwest of Peoria,
skies will generally remain mostly cloudy over the forecast area
well into Sunday morning.
Geelhart
&&
.SHORT TERM... (Through Late Sunday Night)
Issued at 214 PM CDT Sat Aug 5 2023
---------- Key Messages ------------
1. Severe thunderstorms are possible today along I-57 and east
through 6 pm
2. Severe thunderstorms are possible Sunday late afternoon
through the evening hours
------------------------------------
The MCV that entered west-central IL this morning has been slowly
moving east across the area. We still have the possibility of
some discrete supercells developing along and east of I-57 this
afternoon. Some surface based activity is initiating now and may
lead to some severe cells in the next hour or so. The last few
runs of the HRRR model have less thunderstorm activity, however.
Still, the latest mesoanalysis has 1000-2000 J/kg of MLCAPE with
20-30kts of effective shear, with the highest shear near the IL/IN
border. The severe threat remains through 6 pm for this area with
damaging winds and tornados being the primary threats day (5% for
both). The significant tornado parameter is rather low today
being 0.25 now, and decreasing according to the RAP.
After 6 pm, most of the shower/thunderstorm activity will be off
to the east and north of the forecast area. The next system to
affect the area is an upper level low that will move southeast
from SD on Sunday. Much of central IL is in a Slight Risk for
severe weather on Sunday. There may be a few showers/weakening
storms across west-central IL late Sunday morning. However, the
threat for severe storms appears to be late Sunday afternoon when
a line of storm is expected to develop in eastern IA/MO and move
into central IL. This line could be severe with damaging winds
being the primary threat (15%). Showers and storms will likely
linger late Sunday night and Monday morning behind the main line
as the upper low slowly drifts east.
Knutsvig
&&
.LONG TERM... (Monday through Next Saturday)
Issued at 214 PM CDT Sat Aug 5 2023
A few showers will likely linger into Monday across the area as
the upper low drifts east. The area will stay under NW flow aloft
into the weekend with an upper level wave moving SE in the flow
from SD/NE through MO on Wednesday. Right now, the best chance for
severe weather appears to be south of IL. But stay tuned. After
that, another wave could affect the area on Friday, but the signal
is lower for this system.
All in all, expect an active week with cooler temps on Monday (mid
to upper 70s) climbing a bit to the upper 70s to mid 80s for the
rest of the week.
Knutsvig
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 634 PM CDT Sat Aug 5 2023
Fairly widespread cloud deck around 1500 feet persists over
central Illinois this evening. Some erosion is expected along the
fringes, which would allow KPIA to become VFR for a portion of
the night. However, with a mesoscale vortex centered just north of
KDNV, a trend toward IFR conditions appears likely in east
central Illinois, and recent KCMI obs are reflecting the start of
that trend. 18Z HREF ensembles show probabilities of sub-1000 foot
ceilings of 75-95% from KBMI-KDEC eastward peaking in the 03-10Z
time frame. Conditions over east central Illinois likely to be
MVFR into early Sunday afternoon, but sites further west should be
VFR before midday.
Late in the period, scattered storms will be possible, but
uncertainty in the timing/placement will preclude a mention of
VCTS at this time.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
...UPDATED AVIATION FORECAST DISCUSSION...
.SYNOPSIS...
Issued at 209 PM CDT Sat Aug 5 2023
Key Messages:
- Isolated strong storms capable of damaging winds, hail, and
locally heavy rainfall are possible this late this afternoon
into the evening for areas generally east of Highway 183 and
south of Highway 23. Further west across northern Nebraska,
thundershowers are possible this afternoon into the late
evening, however, the severe risk is low.
- A cold front will sweep across western and north central
Nebraska late tonight bringing cooler, below normal
temperatures and gusty winds to the area tonight into Sunday.
- Shower and thunderstorm chances continue on Monday and Tuesday.
Though the severe threat is uncertain at this time, a few strong
storms are possible both days.
Recent GOES-16 WV and RAP 500-mb analysis showed an elongated area
of high pressure holding strong across the Desert Southwest into the
western half of the Gulf of Mexico with multiple low-amplitude
shortwave disturbances noted in the mean flow. Further northwest of
this feature, a trough of low pressure was situated over Oregon,
extending south into northern California. Just to the north of this
system, a high-amplitude upper-level ridge extended north into
British Columbia and Alberta. An upper-level low pressure system was
noted across Quebec with a trough extending across New England.
Closer to home, a potent closed upper-level low pressure system
was centered across central South Dakota with a trough extending
across northern and central Nebraska. At the surface, associated
low pressure of the upper-level system was situated near KPIR
with a trough extending southward near the Nebraska/Iowa border.
An associated surface cold front has occluded across portions of
the Sandhills. At 2 PM CT, temperatures ranged from 65 degrees at
Gordon to 85 degrees at Imperial. Northwesterly winds have become
breezy with recent area observations of 25 to 35 mph. Radar has
begun to show wraparound thundershowers developing western and
southwestern periphery of the low pressure system situated across
central South Dakota.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 209 PM CDT Sat Aug 5 2023
This evening and tonight...The aforementioned surface low will shift
and deepen further across southeastern South Dakota late this
afternoon into the evening, with the surface cold front becoming
oriented from northeast Nebraska to southwest Nebraska by 00Z this
evening.
Strong thunderstorms are possible in two areas across the forecast
area...
1) areas along and east of Highway 183
Satellite is showing an area of agitated cumulus across south
central and far north central Nebraska. The expectation is that
these thunderstorms will continue to initiate across that area for
the next hour or two IVOF the trough. Weak shear and overall weak
forcing has resulted in continued low confidence in the severe
threat across north central Nebraska late this afternoon into the
evening. Despite this, strong storms capable of producing isolated
strong wind gusts, hail up to 1", and locally heavy rainfall are
possible given the modest low-level moisture and marginal
instability. This area of convection is expected to quickly exit
south and east during the evening hours (~00Z) into eastern
Nebraska where the severe threat is increased.
2) areas south of Highway 23
Recent CAMs guidance continues to be in general agreement on
convection initiating along the aforementioned cold front across
northeast Colorado into far southwest Nebraska and northwest Kansas
early this evening. Similar thinking from the inherited forecast
that the bulk of the severe threat will remain to the south of the
forecast area where greatest instability and shear axis is located.
Confidence remains low on this focus area for thunderstorms,
however, a strong storm or two capable of gusty winds are possible
across Chase, Hayes, and Frontier Counties primarily around and
after 00Z. Any storms that track into those counties are expected to
quickly track southeast out of the forecast area with a return to
dry conditions through the night.
Another area of precipitation will be across the northwest Sandhills
into north central Nebraska where the current wraparound
thundershowers are percolating. These wraparound thundershowers
are anticipated to persist across portions of north central
Nebraska overnight, continuing into Sunday with an overall low
severe threat.
Northwesterly winds increase further across the area tonight as the
system becomes vertically stacked near the SD/IA/NE border late
tonight. Wind gusts of 25 to 35 mph will be common with localized
gusts in excess of 40 mph possible across north central Nebraska
within the axis of stronger mid-level flow. This is further highlighted
by the HREF ensemble which is emphasized by a 60 to 80%
Probability of Exceedance of a 40 mph Wind Gust across portions of
north central Nebraska. When looking at Probability of Exceedance
of 45 mph Wind Gust, the percentage decreases substantially, thus
do not anticipate gusts at or above 45 mph.
Sunday and Sunday night...Breezy conditions will persist across the
forecast area on Sunday with peak afternoon gusts ranging from 25
mph across western Nebraska to 35 mph across north central Nebraska.
Overnight thundershowers are expected to continue across north
central Nebraska through Sunday afternoon. The gusts quickly
subside in the late evening with dry conditions returning as the
system occludes and tracks into the Midwest region. Much cooler
temperatures are in store for the region thanks to the cold
frontal passage. Daytime highs are expected to be in the 70s for
areas north of I-80 to the low 80s for areas south of I-80. Some
locations in far north central Nebraska may even see temperatures
in the upper 60s due to persistent cloud cover and precipitation
from the departing system.
Quiet conditions are expected Sunday night with overnight lows
falling into the 50s regionwide. These quiet conditions will be
short-lived as another disturbance brings additional shower and
thunderstorm chances to western and north central Nebraska on
Monday.
.LONG TERM...(Monday through Saturday)
Issued at 209 PM CDT Sat Aug 5 2023
The active pattern continues early next week as multiple
shortwaves eject across the region resulting in continued
precipitation chances for the local area. The severe risk remains
uncertain during this period owing to low confidence given large
spread amongst model guidance. Additional precipitation chances
are possible in the afternoon/evening hours for the latter half
of the week with additional weak shortwaves passing through the
region.
Temperature will remain mild on Monday and Tuesday with highs in the
70s and 80s, though a return to near or slight above normal
temperatures is expected mid to late week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 640 PM CDT Sat Aug 5 2023
Low stratus will continue to push into northern and central
Nebraska this evening and tonight, with a period of MVFR/IFR CIGs
persisting into tomorrow morning. A gradual improvement to VFR is
anticipated from west to east tomorrow afternoon, with VFR then
expected to prevail through tomorrow evening. Confidence in
southwest extent of low stratus remains low for now, so will
forego MVFR inclusion at KLBF, with low-end VFR expected.
Scattered showers and thunderstorms will persist for northern
Nebraska terminals tonight before shifting eastward tomorrow
morning. Winds remain gusty from the northwest through the period,
with gusts of 30 to 35kts possible at times.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Brown
Area Forecast Discussion
National Weather Service Morristown TN
921 PM EDT Sat Aug 5 2023
...New UPDATE...
.UPDATE...
Issued at 914 PM EDT Sat Aug 5 2023
Updating forecast this evening to reflect latest radar trends and
environment. Have added in slight chance POPs across the central
TN Valley and east TN mountains to account for the light showers
currently moving across. We are also monitoring a line of strong
to severe storms moving thorugh southern Middle TN and northern
AL. Models indicate that this line of convection will weaken as
it approaches our area and will most likely not be severe by the
time it arrives. For timing, the line will move into the southern
Cumberland Plateau around 11 PM EDT and then progress eastward
into the southern TN Valley closer to midnight.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 237 PM EDT Sat Aug 5 2023
Key Messages:
1. Higher chances of scattered showers and thunderstorms on Sunday
and Monday ahead of an unseasonably strong shortwave trough.
2. Conditions will be favorable for severe thunderstorms on
Sunday, and especially late Sunday night through Monday afternoon.
Discussion:
Convective debris high clouds arrive tonight ahead of a weak
shortwave moving eastward across the Ohio Valley. We may see some
weakening showers and thunderstorms arrive late tonight and early
Sunday morning, but a weakening trend is anticipated as they move
into a more stable environment across our region.
On Sunday afternoon, a strengthening upper level jet will push
eastward across the mid-Mississippi Valley with areas of
Tennessee, Kentucky, and Ohio within the diffluent exit region of
the jet. A strong shortwave will begin to dive southeast and
amplify the upper-level pattern across the Mississippi River
Valley. In response to the upper diffluence and approaching
shortwave, low- level winds will begin to increase across the
region resulting in increasing effective bulk shear of 25 to 35 kt
by Sunday evening. RAP forecast soundings indicate MLCAPE values
of 3000 to 4000 J/Kg with DCAPE values of 900 to 1200 across the
region. There is high uncertainty in convective coverage on Sunday
afternoon, but if convection does develop, thunderstorms will be
capable of becoming severe with damaging winds being the primary
risk.
As we head into Sunday night, some diurnal stabilization of the
boundary layer is expected, but MUCAPE actually increases
overnight as mid- level lapse rates increase ahead of the upper
trough. In addition, low- level winds will continue to increase as
the upper jet shifts eastward with increasing upper divergence.
This will increase RAP forecast effective bulk shear to around 40
to 45 kt with low-level effective inflow shear of 20 kt. Along
with unseasonably steep lapse rates, MLCAPE on Monday is forecast
to be between 2000 to 3000 J/Kg. To highlight the unseasonable
nature of this synoptic setup, NAEFS forecasts point to 500 mb to
700 mb winds at max of climatology with 850mb winds at the 99.5
percentile. This is an unseasonably strong shortwave trough for
August. Primary risk will be damaging winds and heavy rain rates,
but a low risk of hail and tornadoes will be possible because of
the unseasonably steep lapse rates and shear, respectively. While
instability and shear point to a severe weather risk on Monday,
there are still questions about the overall magnitude and coverage
of severe thunderstorms. A couple important questions heading
into Monday include: 1) what convection occurs during the morning
hours; 2) Does morning convective debris inhibit stronger storms
in the afternoon. These are questions that add to the uncertainty
for Monday, but regardless, forecast conditions point to potential
impactful severe weather across the region. This synoptic setup
is more reminiscent of May than August.
Convection should begin to move east of the region Monday night as
the front moves through and shortwave ridging begins to increase
in the wake of the shortwave axis passage.
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 237 PM EDT Sat Aug 5 2023
Key Messages:
1. Lingering storms behind the front will be possible heading into
Tuesday, and diurnal convection is possible in the afternoons along
the higher terrain this week.
2. Another system will move through near the end of the work week
bringing more widespread storms, but with more uncertain timing as
of now.
Discussion:
By late Monday night there could be some lingering showers and
thunderstorms depending on how quickly the front moves through...
But by Tuesday morning it is expected to be east of the Southern
Appalachian Mountains. Depending on the exact track of the low as it
moves out of the Great Lakes region there could be some wrap around
precipitation during the day on Tuesday. Moisture looks to be very
minimal for Tuesday and the coverage of any developing storms should
be fairly isolated.
More zonal flow will then set up for the middle part of the week
keeping temperatures moderate and near seasonal normals across the
region. We can expect to see some isolated diurnal convection aided
by the orographic lift , but expect any development to remain close
to the higher terrain. Long range models are in agreement that a
fast moving shortwave will likely traverse through the Ohio and
Tennessee Valleys during the second half of the week. The biggest
uncertainty comes on the speed of this system and what time it will
zip through the southern Appalachian region. Faster models have it
moving through Wednesday, while the slower ones hold off until
Thursday. Timing will be key with this system in regards to the
strength and coverage of the associated thunderstorms. Have more
broad brushed PoP chances late Wednesday into Thursday. More of the
models are trending towards the late Wednesday into Thursday
solution for this shortwave, so have the highest PoPs during this
time, and we should be able to trim down the temporal scale of them
once models come into better agreement.
One more frontal system will make a run at the Tennessee Valley
heading into the weekend, but it could get stalled in the Ohio
Valley as it tries to push into the ridge over the Atlantic.
Temperatures should remain at or just below normals through the
weekend.
&&
.AVIATION...
(00Z TAFS)
Issued at 733 PM EDT Sat Aug 5 2023
VFR conditions to begin the TAF period at all sites. Then,
multiple rounds of showers and storms expected at various times
throughout the period, MVFR conditions possible with any passing
shower or storm. Will send amendments as needed. Fog is uncertain
tonight due to potential showers and cloud cover so will not
include in TAFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 73 92 73 93 / 50 70 40 60
Knoxville McGhee Tyson Airport, TN 72 88 73 89 / 60 60 50 70
Oak Ridge, TN 71 87 72 87 / 60 70 50 70
Tri Cities Airport, TN 68 86 68 85 / 20 70 50 70
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...
AVIATION...
Area Forecast Discussion
National Weather Service San Francisco CA
902 PM PDT Sat Aug 5 2023
...New UPDATE, MARINE...
.SYNOPSIS...
Issued at 200 PM PDT Sat Aug 5 2023
Hot conditions will continue to prevail across the inland areas
through Sunday, with a moderate or locally high heat risk possible
for Sunday. A gradual cooling trend will begin for the inland
areas on Monday, with more noticeable cooling for Tuesday as a
trough of low pressure digs off the coast. The immediate coast
will continue to see night and morning low clouds and fog, with
temperatures remaining near to below normal for the period.
&&
.UPDATE...
Issued at 859 PM PDT Sat Aug 5 2023
Not much to add from the previous discussion below. Low clouds have
begun to move inland along the San Mateo Coast and into Monterey
Bay. Expect cooling to be slower-going tonight and even warmer highs
for Sunday. Luckily Sunday remains the hottest day of the forecast
with more onshore flow returning into the work week.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 200 PM PDT Sat Aug 5 2023
Water vapor imagery continues to show high pressure over the
Desert Southwest expanding northward into California, with a weak
upper level disturbance sitting right over the San Francisco Bay
region. This disturbance helped disrupt the marine layer enough
that it clearly relatively quickly this morning. Between this
earlier clearing and high pressure building, temperatures are
warmer today across the region, especially in the inland areas. At
this time, most areas are running 3 to 6 degrees warmer than this
time yesterday, with coastal areas similar to or slightly warmer.
This will make for a mild evening across the region, with the
higher elevations not really expected to see much relief from the
warmth tonight, as some areas in the hills will not fall below 70
degrees. Meanwhile, coastal areas will see the return of the
marine layer, with low clouds and fog expected for the immediate
coast and Monterey Bay.
Tomorrow will be another hot one for the inland areas, with day
time temperatures once again warming another 3 to 5 degrees. This
means that the hottest spots will likely be flirting with or
exceed the 100 degree mark. Palmer
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 200 PM PDT Sat Aug 5 2023
A trough of low pressure will start to deepen along the West Coast
for the first part of the work week. As a result, a gradual
cooling trend with start on Monday, but inland areas will still be
hot. More noticeable cooling will take place on Tuesday though,
as this trough sets up along the California Coast and the marine
layer starts to deepen. At this point in time, Tuesday looks to
be the coolest day of the week, with the influence of the trough.
That said, the Central Coast will remain positioned between the
trough along the Coast and the ridge over the Desert Southwest
through the remainder of the work week and into next weekend. As a
result, some minor fluctuations can be expected in our day to day
temperatures, but for the most part, they should be back in normal
ranges. For coastal areas, expect night and morning low clouds
and fog to persist.
Of interesting note, the ensembles continue to indicate that
Tropical Storm Eugene may track northwest paralleling Baja
through the first part of the week, and then migrate northward
along the periphery of the ridge. That could potentially bring
the remnants moisture into the Central Coast sometime Friday into
Saturday. As of right now, the uncertainty in this happening is
high, but not out of the question. Therefore, this will be
something we will need to continue to watch in the coming days.
Palmer
&&
.AVIATION...
(00Z TAFS)
Issued at 528 PM PDT Sat Aug 5 2023
A very early hint of fall-like season northerly pressure gradient
is developing, ACV-SFO is 6.3 mb (HRRR and NAM under-forecasting
the gradient by ~ 1.5 mb, closer to 2 mb earlier in the afternoon);
e.g. the polar and subtropical jets merging across the CONUS through
next week, suppressing southward the 500 mb subtropical ridge,
passing shortwave trough(s) to the north ushering in a brief
uptick in the WMC-SFO pressure gradient tonight/Sunday morning.
The marine layer depth currently varies from 500 feet Point Sur
to 1000 feet per Fort Ord and Bodega Bay profiler data; additional
lower to mid level thermal ridging is forecast tonight and Sunday
resulting in the marine layer depth either compressing a little
more or holding steady.
The HRRR and RAP models forecast additional wildfire smoke and/or
hazy conditions arriving from southwestern Oregon tonight and
Sunday, primarily affecting slant-range visibilities near sunrise
and sunset. Otherwise it`s near high confidence VFR forecast for
inland, at the immediate coastline expect VLIFR-IFR in fog and
stratus. VLIFR-IFR conditions due to fog and stratus lifting to MVFR-
VFR by late Sunday morning and/or early afternoon.
Vicinity of SFO...Near high confidence VFR forecast for the
period. Increasing northerly pressure gradient and wind developing
in response to building surface high pressure over far northern
California and surface pressures increasing at least briefly
tonight and Sunday morning into the Great Basin. The northerly
pressure gradient (wind), combining with a compressed marine layer
will preclude a stratus intrusion. Gusty west to northwest wind
this evening easing to 10 to 20 knots by mid to late evening, wind
shifting to light northeasterly Sunday morning, then shifting
back to northwesterly or westerly Sunday afternoon and evening.
SFO Bridge Approach...Similar to SFO except slant-range visibilities
especially near sunset and sunrise reduced due to wildfire smoke and
hazy conditions from southwestern Oregon.
Monterey Bay Terminals...Stratus and fog /MVFR-IFR/ along immediate
bay shoreline, not far inland it`s VFR. Increasing northwesterly
winds across the Monterey Bay creates an eddy circulation deflecting
fog and stratus temporarily away from KMRY and KSNS early to mid
evening, then fog and stratus /VLIFR-IFR/ moving in onshore winds
tonight and Sunday morning. Fog and stratus /VLIFR-IFR/ mixing
out to MVFR-VFR by late Sunday morning. Onshore winds 10 to 15
knots this evening, light onshore tonight and Sunday morning,
increasing to 10 to 15 knots Sunday afternoon and early evening.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 859 PM PDT Sat Aug 5 2023
Surface high pressure over the eastern Pacific will build across
far northern California and briefly extend across the Great Basin
tonight and Sunday morning. This will result in ongoing strong and
gusty northwesterly to northerly winds across the coastal waters.
Hazardous, steep wind waves will persist across the coastal waters
in response to strong winds. Light, long period southwesterly
swell and moderate period southerly swell will continue into next
week, then slowly diminishing.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ535-560.
Small Craft Advisory until 3 PM PDT Sunday for PZZ540-565-575.
Small Craft Advisory until 9 AM PDT Sunday for PZZ545.
Small Craft Advisory until 3 AM PDT Sunday for PZZ570.
Gale Warning from 3 AM to 9 PM PDT Sunday for PZZ570.
&&
$$
SHORT TERM...Palmer
LONG TERM....Palmer
AVIATION...Canepa
MARINE...Canepa
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Area Forecast Discussion
National Weather Service Nashville TN
943 PM CDT Sat Aug 5 2023
...New UPDATE...
.UPDATE...
Issued at 943 PM CDT Sat Aug 5 2023
The threat for severe weather has for the most part diminished
across middle TN as the environment becomes capped. Scattered
thunderstorms will continue to work east into the early part of
the overnight. Most of this activity should move out by 1-2 am but
will linger longer over the Plateau. The line of thunderstorms
over KY should remain to the north. Cloud cover overnight should
limit any fog potential but some fog can`t be ruled out in fog
prone areas. An MCV associated with overnight thunderstorms over
KS and OK should reach TN tomorrow afternoon and bring scattered
thunderstorms. Additional thunderstorms will be possible Sunday
night with a cold front. Some of the storms could be stronger
tomorrow with wind and heavy rain the main threat.
&&
.SHORT TERM...
(This afternoon through Monday Night)
Issued at 221 PM CDT Sat Aug 5 2023
Surface low located over IL this afternoon with a warm front
trailing off to the southeast and across the mid state. Cold front
extends southwestward from the low to across southern MO and
northern KN. The cold front and areas just south will continue to
serve as a breeding ground for MCS development going forward.
Currently, the remnants of the latest system covers our
north central and northeastern areas and will continue to
weaken with time. Model data going forward is not very dependable
in terms of futuristic MCS timing and approximate location. That
said, we`ll be adhering to the short term cams and current and
expected trajectory patterns for the forecast through Monday
night.
We are currently outlooked with a marginal risk through tonight.
Expectations are for an mcs to develop across eastern AR and move
eastward and reach our area this evening. Hrrr and Namnest are in
agreement with this expectation. Since its noteworthy, The GFS
also shows some enhancement for this evening, though the Euro is
not in support. Straight line strong to perhaps damaging winds
will be the threat. The degree of afternoon destabilization may be
overdone as the current cloudiness and rainfall may be a little
slower to end. We are getting some better destabilization across
our southwest. The surface low to our north could generate a
little more in the way of helicity magnitudes but that should
generally remain to or north. Localized flooding will also be a
possibility. Cams show up to 1-2 inch localized amounts through
sunrise. Some areas across our northwest have received 1-2 inches
since midnight.
Moving on, perhaps a break for the first portion of your Sunday.
Then we will see convection ramp up once again for the late
afternoon/evening period. At that time, a more vigorous surface low
across nrn IL will contain a southward extending cold front. Shear
values will be picking up with good instability levels in advance of
it. Our entire area is in a slight risk and we do see some better
helicity values of 200+ at that time. Otw, straight line damaging
winds will be the primary threat.
On Monday, we`ll carry highest pops along the Plateau where
instabilities will ramp up significantly by afternoon. The slight
risk will still be in effect for areas east of I-65. Mid level lapse
rates approach 8C at that time with strong cape through the -20C
level. Can`t rule out some hail at that point. Look for improving
conditions by Monday night.
Through Monday night, WPC is carrying areal average qpf amounts of
around 2 inches west to an inch east.
For the near term temps, we should warm into the upper 80s on Sunday
with that non active morning and early afternoon period expected.
More in the way of sunshine will keep us near 90 for Monday.
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 221 PM CDT Sat Aug 5 2023
In the extended forecast, not much pattern change as in general, a
broad troughing regime resides. Westerlies will remain semi-active
but we can hone in on Wednesday and Thursday as rather wet. At that
time, a more robust series of shortwaves will impact our area. The
NBE numbers have shown some copious rainfall amounts with the last
several runs. Looks like the builder will give us 2 inch amounts, or
so, area wide. GFS is showing quite a bit more with the Euro close
to 2 inches. In terms of severe potential, SPC shows some activity
upstream from us on Day 5, but there is no Day 6 eastward
prorogation indicated at this time.
For the extended temps, with the expected clouds and precip for Wed
and Thu along with the aforementioned gentle troughing, temps will
run a few degrees below normal. Then, look for conditions to
normalize by the weekend with near 90 for highs returning.
&&
.AVIATION...
(00Z TAFS)
Issued at 708 PM CDT Sat Aug 5 2023
A broken line of storms is expected to move from west to east
across Middle TN this evening. Heavy rain could cause decreased
visibilities and gusty winds will likely accompany any storm.
Storms should clear CSV by 09Z. Low cigs and patchy fog may
develop overnight...with SRB and CSV being the most likely to
experience deteriorated conditions. Broken mid clouds are
expected to hang around throughout the day on Sunday. Additional
storm development is expected Sunday afternoon, but coverage is
uncertain. Mentioned vcts for now. Winds will remain out of the
west for most of the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 74 90 75 89 / 50 70 60 50
Clarksville 72 89 73 88 / 50 50 60 30
Crossville 67 84 68 82 / 70 70 60 70
Columbia 72 91 73 90 / 50 70 30 50
Cookeville 69 87 71 85 / 60 70 60 60
Jamestown 69 85 68 82 / 70 60 70 70
Lawrenceburg 71 90 72 89 / 50 70 30 50
Murfreesboro 72 92 72 90 / 40 70 50 50
Waverly 71 88 71 87 / 50 50 60 40
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Mueller
SHORT TERM...21
LONG TERM....21
AVIATION.....Whitehead