Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/26/21
Area Forecast Discussion
National Weather Service La Crosse WI
1102 PM CDT Fri Jun 25 2021
.SHORT TERM...(This evening through Saturday)
Issued at 251 PM CDT Fri Jun 25 2021
Surface analysis shows a frontal boundary extending from lower
Michigan through northern IL/central IA. Behind this front, which
passed through last evening/overnight, leftover low level moisture
from shower/storms was producing widespread low clouds and pockets
of drizzle/isolated showers across the forecast area today.
Temperatures as of 2 pm were in the mid 70s to lower 80s with muggy
dew points in the mid 60s to lower 70s.
For tonight, a mid-level shortwave trough (currently moving out of
WY int NE per GOES water vapor) will spin up surface cyclogenesis
over the Central Plains. This low will track along that
aforementioned frontal boundary, lifting north as a warm front to
along I-90 by Saturday morning. Increasing moisture transport ahead
of the low and into the warm front is expected to spread showers and
storms into the area tonight. The showers and storms look to be
fairly widespread going into Saturday as the low tracks through
southern WI.
Airmass going into Saturday will be rather soupy as well with dew
points in the 65-70 degree range/precipitable waters around 2
inches. So, could see some localized heavier rainfall under storms.
In addition, with the low track, could see a small window of strong
to severe storms in the warm sector across portions of northeast IA
into southern WI where greater chance of destabilization takes place.
Otherwise, plan on highs mainly in the 70s, maybe a few lower 80s.
.LONG TERM...(Saturday night through Friday)
Issued at 251 PM CDT Fri Jun 25 2021
Through much of this period, a longwave trough will remain across
the region. As shortwaves move through this trough, there will
periodic chances of showers and storms. The timing of these waves
are highly uncertain, so they are broad brushed through this time
period. High temperatures will range from the mid 70s to lower
80s. Low temperatures will range from the lower 50s to lower 60s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1055 PM CDT Fri Jun 25 2021
Abundant low level moisture will bring low ceilings into the TAF
sites early Saturday morning. IFR ceilings are likely at both RST
and LSE towards daybreak and are expected to persist for much of
the period, perhaps improving slightly to low MVFR in the
afternoon. Can`t rule out some patchy fog before daybreak, but
any visibility reductions the rest of tonight would be more likely
tied to passing showers and/or storms that come into play roughly
after 09Z.
Low pressure and a warm front lifting northward on Saturday will
bring numerous showers and storms through the area during the day.
Recent HRRR runs suggest only isolated convection through mid-
morning, and then fairly widespread activity over the TAF sites
from about 17Z to 03Z Sunday along the front as it stalls overhead.
Any slow-moving showers and storms will be capable of dumping
heavy rainfall over a short period of time. Also can`t rule out a
few stronger storms with gusty winds, mainly for LSE.
Outside of any stronger storms, winds should be mainly light
around 10 knots or less through the period. Direction will
fluctuate depending on the position of the front.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DAS
LONG TERM...Boyne
AVIATION...Kurz
Area Forecast Discussion
National Weather Service Bismarck ND
928 PM CDT Fri Jun 25 2021
.UPDATE...
Issued at 921 PM CDT Fri Jun 25 2021
Showers are still slow to move out of the far south central and
the James River Valley along an inverted surface trough, but the
threat of thunder seems close to zero at this point so took the
mention out of the forecast through 15z tomorrow. Also evaluated
the fog potential a bit closer. There is still some potential for
patchy fog tonight in areas that saw rain over the past two days.
However, we remain skeptical that there will be enough clearing
for widespread fog. Will continue to leave mention out of the
forecast for now.
UPDATE Issued at 608 PM CDT Fri Jun 25 2021
The main area of showers continues to extend from the far south
central northeast and into the Jamestown and Carrington areas.
While most of this rain has been light to moderate, the line
itself has been fairly slow to move east. Thus, a few areas have
received an inch or more of beneficial rainfall. While
thunderstorms haven`t really materialized this afternoon, will
keep a slight chance of thunder in the forecast as a few hundred
J/kg of CAPE are still floating around. A few lingering showers
will be possible through the night behind the main line. Will have
to revisit fog potential for the next update as some of the CAMs
are wanting produce some patchy fog along and east of the Missouri
River. This seems reasonable with light winds forecast and a
moist ground, but there still remains quite a bit of uncertainty
if the sky will clear enough. Thus, will leave it out of the
forecast for now.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 153 PM CDT Fri Jun 25 2021
Scattered to numerous shouts and isolated thunderstorms continue
to track eastward through central ND this afternoon.
It looks like the last chances for thunder are currently moving
through Mandan and Bismarck. Latest surface analysis shows surface
low pressure near The SD border around the Missouri River Valley.
Latest RAP analysis shows around 250 j/kg Cape around Bismarck to
around 750 j/kg near Linton/Selfridge area. Strong vort max around
Garrison to Minot continues to produce widespread showers and
embedded thunder over central into northeast ND. The activity does
scatter out however over the south central. The associated shower
activity along the vort tail extend southwest to just west of
Mandan and then to western Sioux county. Think we would have maybe
an hour to possibly two in the local Bis/Man area for thunder
before thunder and shower chances really drop off. Better rain
chances remain just east of Bismarck and Linton/Selfridge area
into the James River Valley. However, if mid level lapse rates
remain meager, it looks like a continuation of shower activity
with isolated thunder.
Shower activity will linger over the James River Valley through
much of the night, with another chance of showers moves into
northwest ND ahead of a shortwave dropping south from Canada.
Expect Mostly cloudy skies tonight with lows in the mid 50s to
lower 60s. A few lower 50s or even upper 40s area possible over
thee southwest where we see the best chance of a period of clear
skies between the exiting shower activity southeast and the next
system moving in from the north.
The wave dropping south from Canada will keep scattered showers
and isolated thunderstorms in the forecast through the day
Saturday. Activity will not be as widespread as today with the
best chances for thunder in the south central late afternoon or
early evening. Severe weather is not anticipated. Highs are
expected to be mainly in the 70s, but with a few lower 80s
possible.
.LONG TERM...(Saturday night through Friday)
Issued at 153 PM CDT Fri Jun 25 2021
Shower and thunderstorm chances Saturday night and Sunday followed
by mainly dry conditions and a warmup through the work week.
The aforementioned system dropping through on Saturday could keep
some lingering shower chances through Saturday night. Then one
last shortwave drops south through the area on Sunday bringing
another chance of showers with isolated thunderstorms possible.
Then mainly dry conditions with a warming trend look to be in
store through the first half of the work week. A strong upper
ridge building over the Pacific Northwest this weekend will push
slowly eastward into the northern Rockies early next week. There
remains some uncertainty on how this strong ridging evolves late
in the work week and into next weekend. Like this weekend there is
now some support for a northern stream system dropping into the
Northern Great Lakes region, or the Northern Plains, and how this
might impact the upstream ridge. A look at the cluster analysis
for late next week shows support for both a ridge dominating the
forecast area, and also upper troughing over the central plains
into the Great Lakes, which would lead to more tempered heat,
especially over eastern portions of the forecast area. With this
and a pretty wide spread of the NBM ensembles toward next
weekend, we will leave the extended forecast as is. Highs
generally in the 80s, with some 70s possible early in the work
week and inching toward the 90s west, late in the work week. After
this weekend, no significant chances for precipitation are in the
forecast next Monday through Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 608 PM CDT Fri Jun 25 2021
Showers will continue for the next few hours, mainly east of the
Missouri River and into the James River Valley. The site most
impacted by these showers will be KJMS, but some lingering showers
will be possible in the vicinity of KBIS. If skies can clear
enough we may see some patchy fog across the central and east with
light winds in the forecast and moist ground. However,
uncertainty regarding the cloud cover precludes mention of fog in
the TAF at this time for any particular site. Widely scattered
showers and a few thunderstorms will possible once again across
all of western and central North Dakota Saturday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ZH
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...ZH
Area Forecast Discussion
National Weather Service State College PA
1103 PM EDT Fri Jun 25 2021
.SYNOPSIS...
An anomalous upper level ridge over the north Atlantic will
build and retrograde westward into the Mid Atlantic region this
weekend through early next week, bringing a gradual increase in
heat and humidity. A slow-moving cold front is then likely to
push into Pennsylvania late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Latest radar trends show very light rain showers moving in from
the west and drying up across the northern Alleghenies. Farther
upstream, heavier showers continue between Cleveland and Erie
along a warm front. Hires guidance shows this precip lifting
northward into the Glakes/NY through the overnight. Thus
knocked PoP below 25% in the NW zones.
Over the eastern part of the state, a marine layer will slide up
the coast and bring low clouds and moisture after midnight. This could
produce a bit of late night drizzle over the western Poconos,
as moist low level southerly flow is forced to ascend the higher
terrain. 0-1km RH values approach 100 pct in this area late
tonight.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Low stratus over the SE will erode by mid morning Saturday.
Took temperatures down a few degrees vs the NBM for the morning
hours in this area, but thinking temps will rebound quickly in
the afternoon, coming back in line with the NBM guidance after
18z.
Latest HRRR shows a few showers popping in the lower Susq late
morning / early aft on Sat, as low stratus mixes out but high
dwpts remain in the midst of increasing instability. Will raise
PoPs up to slight chance in this area to account for this.
Capping at 700 mb should prohibit tstms.
Warmest thermal axis at 850 mb sets up over the western half of
PA Sat afternoon as warm air spills in from the west. This,
combined with early cloud cover in the east, will likely result
in only a few degrees difference in MaxT between BFD and MDT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Very little to change/add to the previous disco with this late
evening update. HHH is on the way. Mon-Wed still looks like a
solid chc for a Heat Advy (100+ HI) in the Lower Susq. Still
playing temps a deg or two cooler than blend of guidance thru
that period.
Prev...
All guidance supports rather hot and humid conditions Sunday
(and on average 7-10 deg F above normal) but, with anomalous
upper ridge centered just off the Mid Atlantic coast. Warm temps
aloft should largely suppress PM convection. However, can`t
rule out an isolated, pulse-type shower/storm developing over
the elevated heat source of the Appalachians. Mixing down model
850mb temps of around 18C translates to highs ranging from the
mid 80s over the highest terrain of the Alleghenies, to the low
90s in the Susq Valley.
Guidance continues to depict a western Atlantic ridge moving
westward over the Eastern US and amplifying throughout the
weekend into next week. Anomalously high 850mb temperatures
along with the southerly surface winds will allow most locations
to see temperatures rise above normals into the mid to upper
80s, with some locations peaking into the low 90s. The heat
will be accompanied by increasing dew points, which may result
in heat indices climbing into the mid 90s. The warm moist
airmass will also introduce the chance or diurnal convection.
Lack of deep layer shear will likely keep any storms below
severe limits.
The heat, humidity, and daily chance of scattered afternoon
showers and storms will continue through the week until a cold
front sweeps across the region late Thursday into Friday. There
is a degree of uncertainty to the strength and timing of this
front due to model differences. Late next week into the holiday
weekend, the GFS stays dry while the EC is wetter, so the
conditions of the holiday weekend are very uncertain.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Latest nighttime satellite imagery shows low clouds developing
across mid Atlantic through the DC area and spreading northward
within a marine layer. Low clouds will push into the
central/southeast airfields after midnight tonight with a stray
shower possible mainly east of the Susquehanna River or in the
Northern Alleghenies. Expect several hours of MVFR cigs at
MDT/LNS and possibly at IPT/UNV, with a period of IFR cigs also
possible for LNS and perhaps MDT prior to daybreak.
Cigs will lift and scatter out from southwest to northeast
through the morning hours Sat, with all airfields likely back to
VFR by 15z. Expect winds to continue from the south with
afternoon gusts 15-20 kts.
Outlook...
Saturday...Improving cigs east w/ showers/storms possible mainly
in northern PA.
Sunday...Scattered afternoon thunderstorms with brief,
localized restrictions.
Monday-Tuesday...More numerous, mainly afternoon and early
evening showers and thunderstorms as a slow moving cold frontal
boundary slides east across the state.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert
NEAR TERM...Lambert/Colbert
SHORT TERM...Lambert/Colbert
LONG TERM...Dangelo/Wagner
AVIATION...Lambert/Colbert
Area Forecast Discussion
National Weather Service Des Moines IA
716 PM CDT Fri Jun 25 2021
.DISCUSSION.../Tonight through Friday/
Issued at 301 PM CDT Fri Jun 25 2021
Today and Saturday:
The large-scale pattern across the central CONUS remains under the
influence of a broad trough, keeping mid to upper-level flow west-
southwesterly. The short-wave that triggered last night`s convection
has moved into the Great Lakes Region. There has been subtle hints
of subsidence across portions of central and northwestern Iowa via
satellite imagery, but plenty of lingering moisture is still present
and several areas have remained under overcast skies. Additionally,
the activity last night has left several outflow boundaries across
the region, and these can be seen by variable wind directions across
the upper Midwest as well as sudden discontinuities in temperatures
and dewpoints. Another vort max is moving across the central Plains
this afternoon will be moving through Iowa during the evening hours,
continuing overnight. While this is ongoing, a surface low
developing near the OK Panhandle will begin to slowly lift northeast
across Kansas toward the area. This will continue to push warm moist
air into the region, and provide weak lift for shower and
thunderstorm generation. There is still some question as the
strength of convergence that will be available, because synoptically
there will not be much this afternoon. However, differential heating
this afternoon where skies clear could potentially strengthen one of
these outflow boundaries in the region, which could increase the
convergence and thunderstorm potential. CAMs today initiate weak
convection across eastern portions of the forecast area after 18z
today, though these are not maintained for a long period of time.
After 20-21z, there is more development in the CAMs as the mid-level
vort max moves across the area. This is mainly focused for areas
north of Interstate 80, where there currently sits a stationary
boundary. There will be a decent amount of instability throughout
most of the forecast area, with the RAP continuing to depict nearly
2000 J/kg of SBCAPE. However, mid-level lapse rates are not
exceeding 7.0 C/km north of Interstate 80 this afternoon where
convection is expected to initiate. This will make it difficult for
strong updrafts to get going. Flow in the lower-levels of the
atmosphere remains weak, and does not increase until above 500 mb.
Therefore, the deep layer shear will be rather weak for a large
amount of time. It may increase later into the evening. Even if
parcels become surface based, there will not be a whole lot to
organize it until well above the CBL. This complicates the severe
threat with these storms. With the overall lack of lower level flow,
the tornado threat does not seem present. The only factor that could
change this is activity in the immediate vicinity of an outflow
boundary, but it will have to be timed and located perfectly. With
moderate instability, deep convection will still present hail and
stronger wind chances this evening for areas north of Interstate 80.
Late in the evening, as the surface low continues to move
northeastward, convergence then increases in for areas south
Interstate 80, and CAM guidance this morning has had decent
agreement on stronger convection after 04z continuing into Saturday
morning. Like with the convection to the north, hail and wind gusts
could be possible, but low-level flow will still be lacking in this
area and thus not much deep layer shear, thus only the marginal risk
for severe weather this evening. Once again, flooding may become an
issue. For the convection north of Interstate 80, motion may occur
parallel to the stationary boundary that is in place. Storm motions
will not be overly fast, meaning that an efficient storm could drop
a lot of rainfall over just an hour or two. Areas north of
Interstate 80 though will still be able to handle heavier rainfall
before major issues start to arise. The bigger flooding concern will
areas south of Interstate 80. Last night flooding occurred as some
thunderstorms cumulatively produced 4 to 6 inches of rainfall over a
6 hour period. This same area may be able to see another 1 inch
tonight, with locally higher amounts likely. Flash Flood Guidance
indicates that 1 to 1.5 inches over 3-6 hours could trigger more
flooding, especially south of Interstate 80. Therefore, have issued
a Flash Flood Watch through Saturday morning for southern portions
of the forecast area.
This first round of convection will move east-northeast by 12-14z
timeframe, as the low surface low pressure moves across the state.
The larger short-wave trough axis will begin to slide eastward,
continuing weak H5 height falls into Saturday afternoon. Behind the
surface low pressure system will be a cold front, a main convergence
source for shower and thunderstorm activity on Saturday. GFS depicts
an environment with SBCAPE over 2000 J/kg ahead of the cold front
during the afternoon, with other guidance between 1000-1500 J/kg.
However, convective debris from the earlier morning activity may
hinder destabilization Saturday afternoon ahead of the boundary. If
destabilization occurs, low-level flow should be a bit stronger than
it is today as the surface low moves across the area, with plenty of
deep layer shear still around to support the organization of a few
storms. With this possibility, the marginal risk has been expanded
to cover more of Iowa for severe storms on Saturday. The threat at
this time remains very conditional.
Extended:
Persistent southwest flow will bring several short-wave
perturbations across the region for the rest of the week. Expect
multiple rounds of rain showers and thunderstorms. Temperatures will
range from the mid 70s to the mid 80s throughout the week. By the
middle of the week, GFS and ECMWF continue to resolve the high
pressure over the eastern CONUS differently, with the GFS stalling
out the high pressure creating blocking pattern through the week.
There will be dry periods throughout next week, but given the
uncertainty of how long this trough will be parked across the
Midwest, have not deviated much from blended guidance in the
extended forecast.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 715 PM CDT Fri Jun 25 2021
Scattered showers and thunderstorms will persist for much of the
forecast period across central Iowa. Mostly VFR ceilings but
increasing MVFR coverage overnight into Saturday morning as
precipitation persists. Winds will be variable at 5 to 10 mph for
much of the period with stronger gusts in and around
thunderstorms.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT Saturday for IAZ084>086-092>097.
&&
$$
DISCUSSION...Krull
AVIATION...Cogil
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1005 PM EDT Fri Jun 25 2021
.UPDATE...
Pronounced convectively enhanced shortwave anchored over southeast
Michigan late this evening. Infusion of larger scale mid level
ascent still proving efficient within the background of a highly
moist, weakly unstable environment -- supporting a persistent,
chaotic coverage of showers locally. Radar trends suggest a window
of greater stability will emerge within the immediate wake of this
vort max across northern sections, offering a brief reprieve from
convective potential overnight. Southern sections remain more
susceptible to development, owing to steady nocturnal moisture flux
and effective retention of a weakly unstable profile under
persistent 30-40 knot southwest flow across the 850-925 mb layer.
Recent HRRR guidance points to an increase in shower coverage from
south to north through the morning hours within this pattern, likely
augmented by the northward migration of the composite frontal
zone/outflow now fixated near the OH/MI border. Locally heavy
rainfall a clear risk to accompany any development, but window for
possible organized convection and accompanying severe risk remains
muted given limited instability.
Minor evening forecast update to account for near term trends and
expectations for the remainder of the night.
&&
.PREV DISCUSSION...
Issued at 749 PM EDT Fri Jun 25 2021
AVIATION...
Southeast Michigan arrives within the immediate wake of an exiting
mesoscale convective complex late this evening. A general increase
in larger scale subsidence and resulting deeper layer stability
suggests diminishing potential for additional convective development
prior to 06z. Lingering pockets of showers may afford brief
disruption to visibility, but a larger scale response appears
unlikely. Very moist low level profile ensures a high coverage of
MVFR stratus tonight, but with a persistent southwest gradient
limiting prospects for fog development despite the high near surface
moisture content and recent rainfall. Gradual mid level
destabilization occurs as the main moisture axis lifts back
northward late tonight and Saturday. Recent model guidance suggests
a gradual increase in coverage of showers from south to north during
the morning period. Confidence in thunderstorm coverage and timing
Saturday remains very low.
For DTW...Lingering showers in MVFR within prevailing southwest
winds this evening. Increasing stability precludes including a
defined mention for thunder going forward tonight. Greater risk for
thunderstorms appears to develop north of DTW Saturday.
DTW THRESHOLD PROBABILITIES...
* High for ceiling at or below 5000 feet through the TAF period.
* Low for thunderstorms tonight and Saturday.
PREV DISCUSSION...
Issued at 416 PM EDT Fri Jun 25 2021
DISCUSSION...
Areas generally along and south of I 96 have been upgraded to a
Slight Risk with a 5% tornado probability. The potential for tornado
development remains highly conditional to any breaks in the cloud.
Need to stress it will only take a short time period of insolation
to generate surface based instability given peak late June incoming
solar radiation power. Most recent hires soundings point to a
relatively shallow high CAPE density profile that is typical in mini-
supercell setups along with very low LCL heights. Given vorticity
rich environment immediately in advance of MCV feature, the
potential exists for mini-supercell activity for any area that
experiences sunshine between 20-02Z. See Update discussion issued
earlier for more information.
Will continue to monitor observed rainfall amounts versus forecasted
QPF totals over the coming forecast periods for the need of a Flash
Flood Watch or Flood Watch. The main deep moisture axis or
atmospheric river of near/greater than 2.0 inch PWAT that MIMIC-TPW
product shows overhead is forecasted to remain in vicinity of
Southeast Michigan through the upcoming weekend. However, the
details do matter as model data does show a northern migration of
the axis to points along and north of M46 by midday Saturday, then
eventually wavering down to south of I 94 and south of Michigan
border by late Sunday. Low confidence exists and it remains
difficult to pin down exactly where deep convective/highest rainfall
rates on a 6 hour by 6 hour basis. Because of this low temporal/low
spatial certainty, will be forgoing the issuance of a Flood Watch or
Flash Flood Watch this issuance. Given dry antecedent soil
conditions and relatively lower amounts the feeling is that any
flooding issues this evening can be addressed with short fuse
Urban/Small Stream Advisories or Flash Flood Warning.
Anomously, deep upper level composite trough digging into the
Dakotas and corresponding height falls will cause main baroclinic
zone axis to lift northward as a warm front on Saturday. Models
disagree on amount of activity before noon, with latest extended
runs of HRRR relatively dry and HREF 6 hourly ensemble mean rainfall
amounts of less than .5 inch. By afternoon, two items worth
monitoring will be severe weather risk, and the potential for the
training of convection during the late afternoon and evening. Latest
Swody2 includes Southeast Michigan as a Marginal Designation for
severe weather. All indications are that opacity of cloud will be
less which will result in greater destabilization acorss the cwa.
Model soundings support low convective heights resulting in surface
based and mixed layer CAPES of potential 2000 J/kg or greater. Main
axis of kinematics will reside over north half of Lower Michigan
including northwern sections of the cwa, 0-6km bulk shear of +35
knots. Unidirectional wind direction and approximately 50 knots wind
magnitudes down to 4000 ft agl points to much more organized
damaging wind potential. The low confidence part of the forecast
moving forward is exactly where the activity is favored, models
suggest some capping/CIN centered at roughly 5.5 kft agl building in
from the south. Attm, the higher potentia for linear mode/smaller
dyanmic bow echo activity appears to be north of I 69. With that
stated, the potential for large Cape density through the tropopause
and hires signal for discrete cells may potentiall bring all severe
types in play.
Increasing upper level jet entrance region dynamics combined with
deep potential vorticity reservoir is expected to result in low
pressure tracking across portions of Wisconsin and northern Great
Lakes/SOO on Sunday. A ton of questions exist on where exactly the
deep synoptic forcing will occur. However, high confidence exists
that main midlevel moisture axis 700-500mb will reside directly over
Southeast Michigan during the day on Sunday. Models do suggest a
persistence setup with diabatic heating leading to 1500-2000 J/kg
surface based CAPE and unidrectional southwest wind profile. Latest
Swody3 includes Southeast Michigan in a Marginal Risk for Severe
weather.
MARINE...
Unsettled weather continues over the central Great Lakes today into
tonight as a wave of low pressure tracks along a stalled frontal
boundary. Moisture is abundant across the region with numerous
showers, heavy at times, and a few thunderstorms likely to continue.
Wind gusts will generally remain between 20 and 25 kt through
midnight with Small Craft Advisories in effect for all nearshore
waters outside of Saginaw Bay. Any thunderstorms will have potential
to produce locally stronger winds and higher waves which would lead
to localized hazardous boating conditions as well. Southeasterly
winds this afternoon veer to southwesterly tonight as the low
pressure departs the region. A brief lull in precip is possible
early Saturday, but another round of showers and storms is then
likely the rest of the day as southwest flow advects in another
surge of moisture. A second round of Small Craft Advisories may be
needed over western Lake Erie and Lake St. Clair on Saturday.
Numerous showers and storms are likely to continue Sunday and into
the early week.
HYDROLOGY...
A frontal boundary will stall across the Great Lakes with a
subtropical airmass lifting into the region. Very moist conditions
will hold through at least the weekend. This environment combined
with passing low pressure systems and upper-level disturbances will
bring several rounds of on and off heavy rain showers in addition to
periods of embedded thunderstorms. Shower and thunderstorms will be
likely today with best chances occuring this afternoon and evening.
While storm total accumulations will be highly dependent on
thunderstorm activity and where the frontal boundary over northern
lower michigan sets up, the first opportunity for widespread heavy
shower and embedded thunderstorm activity will be this afternoon
into the evening with the passage of the first low pressure system.
Additional rain activity, heavy at times, will continue Saturday
into Sunday following the passage of the low pressure system.
There is extremely high confidence that rainfall totals will
reach or exceed 1.5 inches across most portions of SE MI by Sunday
morning, with possible totals ranging somewhere between 2-4 inches.
Localized higher rainfall amounts expected with thunderstorm
activity. Impacts include rises on area rivers with the potential
for flooding in urban and low-lying areas. An isolated to scattered
risk for flash flooding will exist over all of SE MI with this set-
up, also highlighted in WPCs Excessive Rainfall Forecast.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......MR
AVIATION.....99
DISCUSSION...CB
MARINE.......TF
HYDROLOGY....DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
930 PM EDT Fri Jun 25 2021
.SYNOPSIS...
High pressure will shift off the Atlantic coast this weekend into
next week. This will bring moisture back to the region and a return
of afternoon showers and thunderstorms through the end of next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 930 pm Friday: Regional radars depict the main Piedmont and
coastal band of showers dissipating this evening, while spottier
showers redevelop a bit farther west on outflows. Cannot rule out
some isolated showers developing in the deepening moisture east of I-
77 late this evening and early overnight, with some mesoscale models
showing isolated showers over the NC foothills and western Piedmont
late tonight in weak upslope. Any rain showers will be isolated and
light. Temperatures are falling a touch ahead of the forecast, but
invading and lowering clouds from the east will halt the fall
overnight and no mid-course corrections will be made on modifying
minimum temperatures.
Otherwise, the offshore ridge will retrograde slightly over the next
24 hours and this will restore more seasonable weather for the
forecast area. Low-level flow will veer toward S and moisture flux
will improve. The subsidence inversion will weaken, which along with
warmer near-surface temps suggests diurnal convective chances will
be better on Saturday afternoon compared to the past few days. Some
of the mesoscale models, namely the HRRR and NAMNest, do indicate
surprisingly little convective development during the aftn,
seemingly a result of delayed warming due to the morning stratus.
The NAMNest in particular tends to overdo surface moisture and these
kinds of stratus events, so we`re not ready to totally buy that
idea. Forecast PoPs are generally lower than our previous forecast,
but still close to what would be expected climatologically. Max
temps inch back almost to normal.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 215 PM EDT Friday...Surface and mid level high pressure will
be in place off the Mid-Atlantic coast for Sunday and Monday leading
to easterly flow off the Atlantic and increased moisture. Despite
the lack of forcing, expect showers and thunderstorms each afternoon
and evening with the highest chance in the mountains.
Temperatures through the period are expected to be near to just
above climo.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 215 PM EDT Friday...Ridging will remain in place along and off
the Atlantic coast for next week. While the ridging may weaken some,
a mid level trough and associated cold front dropping into the Great
Lakes area looks to stay well to our northwest. Thus, our area will
remain in the warm and moist air mass in place from this weekend.
Mainly diurnal showers and thunderstorms are expected with the
highest chance most days in the mountains. Highs will be near climo
each day and lows slightly above climo each morning. In other words,
a pretty typical summer pattern is expected next week.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: As diurnal cumulus/stratocumulus continue to
slowly dissipate this evening, attention turns to the MVFR level
clouds moving west from the Carolina Piedmont and the coastal plain.
This activity will make slow progress toward the terminal forecast
area and VFR conditions are expected for much of the night. MVFR to
IFR bases will arrive in the easterly flow circa 08Z near KCLT and
closer to 10Z/11Z at the Upstate TAF sites. Spotty showers will be
possible as well in the Atlantic moisture, but with confidence too
low to mention through Saturday morning. Anticipate very slow
improvement to VFR bases by late morning and early afternoon on
Saturday, but with scattered thunderstorm chances ramping up 18Z to
00Z. Winds will be light and some flavor of ENE to ESE early,
becoming more southerly through the period. MVFR visibility in light
fog is most likely overnight from KAVL to KHKY.
Outlook: Deepening moisture will result in chances for afternoon and
evening showers and thunderstorms through Wednesday. Mountain valley
fog and low stratus will be possible each morning as well.
Confidence Table...
01-07Z 07-13Z 13-19Z 19-00Z
KCLT High 100% High 86% High 82% High 100%
KGSP High 100% High 89% High 86% High 100%
KAVL High 100% High 100% High 95% High 100%
KHKY High 100% Med 72% High 84% High 100%
KGMU High 100% High 89% High 80% High 100%
KAND High 100% High 100% High 88% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...SCW
NEAR TERM...HG/JPT
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...HG/JPT
Area Forecast Discussion
National Weather Service Lincoln IL
857 PM CDT Fri Jun 25 2021
.SYNOPSIS...
Issued at 646 PM CDT Fri Jun 25 2021
Thunderstorms will develop across central Illinois this
evening...particularly along and north of a Shelbyville to Paris
line where some of the storms could potentially produce damaging
wind gusts and heavy rainfall. The storms will gradually diminish
toward dawn Saturday.
&&
.UPDATE...
Issued at 857 PM CDT Fri Jun 25 2021
Thunderstorms continue to develop along an outflow boundary from
central Missouri E/NE into central Illinois this evening. The
storms are being aided by a 30-40kt 850mb jet oriented from the
Ozarks northward into Illinois. 0150z/850pm radar imagery shows
the strongest cells along a Jacksonville...to Lincoln...to
Bloomington line. Based on radar trends and latest HRRR forecast,
think the line will gradually shift southward and will focus
along the I-72 corridor for the next few hours. While overall
severe threat will decrease as daytime instability wanes,
attention will turn to potential flash flooding as training echoes
drop locally heavy rainfall across that area. Most model guidance
suggests the rainfall will slowly decrease in intensity after
midnight as the precip becomes more scattered in nature toward
dawn Saturday. Updated the forecast to better reflect PoP trends
for the remainder of the night.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 343 PM CDT Fri Jun 25 2021
Surface analysis this afternoon depicts a stationary front
stretched from northern IL into IA well north of the area. An
outflow boundary is positioned across southeast IL into central MO
with convection ongoing in our far southeast IL counties as well
as new activity firing over central MO as of 3 PM. Elsewhere, a
break from the precipitation is occurring with some breaks in the
clouds noted across west-central portions of the state. SPC
mesoanalysis depicts MLCAPE starting to build northward with
clearing, though we remain capped (50-150 J/kg) from about I-70
northward from earlier convection. This will prevent anything from
developing in these areas for the next few hours. Confidence in
the evolution of activity going into tonight remains low. Once the
CAP erodes, scattered storms should develop across west-central
IL along the ouflow boundary sometime later this afternoon or
early evening, which the 25.18Z HRRR picks up on. However, CAMs
have not been performing well. The idea is that coverage will
increase by tonight as a few mid-level waves ripple through the
southwest flow aloft and the LLJ kicks in. Strong to severe storms
remain possible across locations south of I-74 with damaging
winds and large hail being the main threats. However, decent low-
level shear with a boundary in the area could support a brief
tornado or two.
Additional rainfall amounts through Saturday morning look to range
from 1-2" north of I-70, with higher amounts possible where storms
train. With 1 to 3 hr flash flood guidance ranging from 1.5 to 2.5"
due to recent soaking rains. Because of this, a Flash Flood Watch
remains in effect for counties north of I-70 through Saturday
morning.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 343 PM CDT Fri Jun 25 2021
The upper-level pattern remains in a blocking regime this weekend
and even into the new week, keeping periods of showers and storms
possible. Shower and storm chances look to taper off Saturday
morning as the LLJ recedes. Additional thunderstorm development
looks likely along any remnant boundaries by the afternoon into
evening hours of Saturday, pending how quickly the atmosphere
destabilizes after overnight convection. A similar story going
into Sunday with the same set up. All in all, additional rainfall
amounts Saturday through Monday morning look to range from 1-3"
north of I- 70.
Shower and storm chances remain possible through a good portion of
the week with the blocking pattern keeping southwest flow positioned
over the local area. Let the NBM handle PoPs through the week for
the time being. The pattern finally begins to change by the end of
the week into next weekend as the ridging over the eastern
CONUS/Atlantic breaks down.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 657 PM CDT Fri Jun 25 2021
Main aviation forecast concern will be timing of convection
tonight. Scattered thunderstorms have developed across central
Illinois early this evening, but these appear to be missing the
terminals. Further upstream, more numerous cells across
central/northern Missouri are spreading northeastward across the
Mississippi River and will likely impact the TAF sites later this
evening into the overnight hours. Based on radar trends and HRRR
forecast, have included VCTS at KSPI after 02z...then further
northeast to KCMI after 04z. Most models suggest the storms will
diminish overnight, with only showers lingering across the area
after 09z. As happened last night, forecast soundings show MVFR
ceilings overnight into at least Saturday morning. It appears
ceilings will improve to VFR at all sites except KPIA by midday.
Winds will initially be S at around 10kt this evening, then will
veer to S/SW and gust to around 25kt from late Saturday morning
through the afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT Saturday for ILZ027>031-036>038-
040>057-061.
&&
$$
UPDATE...Barnes
SYNOPSIS...Barnes
SHORT TERM...NMB
LONG TERM...NMB
AVIATION...Barnes
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
843 PM PDT Fri Jun 25 2021
Updated Aviation Discussion
...UNPRECEDENTED HEAT WAVE EXPECTED THIS WEEKEND INTO NEXT WEEK...
.SYNOPSIS...An anomalously strong high pressure system aloft is
beginning to build into the Pacific Northwest and will continue to do
so this weekend, bringing a stretch of unusually hot weather to the
region. The resulting heat is likely to break numerous high
temperature records, with some all-time heat records in serious
jeopardy. Coastal areas will be cooler, especially along the beaches.
The hottest day overall appears to be Sunday, with only minimal
cooling expected Monday - mainly for the coastal valleys and perhaps
the Eugene/Corvallis area. The most extreme heat is expected to wane
somewhat next week, but inland temperatures are still expected to be
well above seasonal normals.
&&
.SHORT TERM...Today through Monday...Perhaps the most intense
heatwave for our region since the late 19th century - or at
least close to it - is beginning to take shape across the Pacific
Northwest as anomalously strong high pressure builds aloft.
As of 2 PM, temperatures were generally running 5-10 deg F warmer
than they were that time Thursday, with mid to upper 80s fairly
widespread for the interior valleys. Latest (20z) HRRR analysis shows
850 mb temps running around +18 deg C at Salem, and this may be the
last time they see 850 mb temps below +20 deg C until next Tuesday or
Wednesday.
While today is what would normally be considered a very warm to hot
day for our inland valleys, Saturday appears to be roughly 10 deg F
hotter as 850 mb temps climb through the lower 20s deg C. As such,
latest (13z) NBM guidance shows an 80 percent chance of KPDX reaching
100 degrees Saturday afternoon, with 106 deg F favored by
deterministic NBM guidance. For Salem, NBM guidance shows a 76%
chance of reaching 100 degrees, with 104 deg F favored by
deterministic NBM guidance. Given slightly lower values forecast by
most MOS guidance, and the fact that 102 deg F is the monthly high
temp record for PDX, we have hedged our forecast slightly below those
numbers, but the difference in sensible weather will be minimal. The
bottom line here is that triple-digit heat is expected to begin for
most of our inland valleys Saturday, and will only intensify for
Sunday.
There has been a lot of (well-justified) hype lately regarding the
high temperatures shown by many models (and the National Blend of
Models) Sunday and Monday, with some showing all-time high
temperature records being obliterated by 5 to 10 degrees. While
models seem to be well in agreement of +28 deg C to +31 deg C for 850
mb temps during that period. The all-time record for 850 mb
temperatures at KSLE per SPC sounding climatology is +28.3 deg C. So,
just considering 850 mb temps, we would be in the ballpark of
all-time record highs. But there are additional considerations.
Recent model runs continue to show some easterly flow developing
through the Columbia Gorge Sat night/Sunday which could potentially
maximize the potential heat at the surface given the air mass aloft.
For example, mixing down 850 mb temps of +30 deg C dry-adiabatically
to the Willamette Valley floor would yield sfc temps of +43 to +45
deg C, or 109 to 115 degrees F. We are generally not forecasting
temperatures that hot just yet, but 110 deg F certainly appears to be
within reach for Portland, Salem, Vancouver, Hood River, and
surrounding areas both Sunday and Monday. Models are suggesting a
southerly wind reversal developing along the coast Sunday night and
Monday, and they seem to be enhancing the strength of it. This may be
good news for coastal valleys, especially Van Duzer Corridor
southward. The 18z NAM appears potentially strong enough with a
southwesterly marine push to keep Eugene in the 90s Monday while
areas to the north continue to bake in triple digit heat.
After nearing monthly heat records on Saturday and possibly all-time
heat records on Sunday, temperatures will struggle to fall below 70
degrees in many areas at night. Downtown and inner eastside Portland
will be slowest to cool each night, given their urban heat island
effect. It is fathomable that some of these neighborhoods will fail
to fall below 80 degrees for a 60 to 72-hour period between Saturday
morning and Monday night. Unprecedented warm nights will offer little
relief from the daytime heat, compounding the danger of heat-related
illness for those without access to air conditioning. Areas outside
of city centers will be relatively cooler, but even the cooler
outlying areas will see lows mainly in the 60s and lower 70s Saturday
night and again Sunday night. Even the mountains will be very warm at
night, with areas along and above thermal belts stuck in the 70s or
perhaps even lower to mid 80s for lows.
In essence, the immediate coast will be the only outdoor place where
people can truly escape the heat the next few days. Those stuck in
inland areas without access to air conditioning are in real danger of
heat-related illness, especially in Downtown Portland and the inner
eastside of Portland. People in these areas should determine where
cooling shelters are available in their area, or will likely need to
be creative about finding ways to keep cool during this unprecedented
heat wave.
No changes to the existing Excessive Heat Warning. A Fire Weather
Watch has been issued for the western slopes of the Washington
Cascades, as well as the North Oregon Cascades and foothills, due to
the easterly breezes expected there late Sat night through Mon
morning. Weagle
.LONG TERM...Tuesday through Friday...The long term forecast looks to
be disappointing for anyone inland who is looking for substantive
relief from the heat. The southwesterly marine push expected to cool
off the coastal valleys Monday will likely become more prolific
Monday night and Tuesday as 500 mb heights fall a bit, mainly due to
an upper low lifting north across our offshore waters. This may even
allow some low clouds into the coastal valleys Mon night and perhaps
Tue night, along with more widespread "cooling" inland. The result
will be much more pleasant temps for the coastal valleys Tue/Wed,
while the inland valleys fall into the upper 80s to mid 90s for highs
- still a good 10 to 20 degrees above late June/early July normals.
Will need to watch the above-mentioned upper low closely, as any
closer of an approach could bring the chance of isolated
thunderstorms Mon/Tue. With the 12z ECMWF ensembles showing little
chance of 500 mb heights lowering below the upper 5800 meter range
for the remainder of the week, the marine layer will likely remain
very shallow and thus temperatures will remain several degrees above
normal for the foreseeable future. Weagle
&&
.AVIATION...06Z TAF: A strong upper level high continues to
strengthen over the Pacific Northwest this weekend. This is
resulting in predominately VFR flight conditions under clear
skies across the region.
The exception to this will be along the coast. Guidance is
suggesting that some IFR/LIFR conditions could develop along
portions of the coast, with the greatest chance around KONP. At
this time these lowered flight conditions will possibly develop
starting around 06Z Saturday to 08Z Saturday, but chances of this
happening are around 20-30% at this time. Confidence in IFR/LIFR
conditions impacting KAST or KTMK are less than 20% at this
time.
Also, high density altitude hazards may manifest through the
weekend as high temperatures are expected to range between
100-110 degrees for the interior lowlands and 90s for the
Cascades and Coastal Ranges.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...VFR under clear skies expected to continue
over the next 24 hours. /42
&&
.MARINE...No immediate concerns as northerly flow will continue
over the waters through at least Sunday afternoon. Flow will
begin to change over the inner waters Sunday evening and Sunday
night as a surface low develops offshore, resulting in a
southerly wind reversal. Southerly winds should develop over the
outer waters as well, most likely late Sunday night into Monday
morning. Model guidance continues to support small craft level
wind gusts around 25 kt Sunday night into Monday, but the
probability of this occurring is between 50-60 percent. For the
outer waters, longer fetch northwesterly winds may result in a
building swell and steep seas to 8 feet. This may also warrant a
Small Craft Advisory for late Tuesday and Tuesday night.
-TK/JBonk
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning from 10 AM Saturday to 11 PM PDT Monday
for Cascade Foothills in Lane County-Cascades in Lane
County-Central Coast Range of Western Oregon-Central
Columbia River Gorge-Central Willamette Valley-Coast Range
of Northwest Oregon-Greater Portland Metro Area-Lower
Columbia-Northern Oregon Cascade Foothills-Northern Oregon
Cascades-South Willamette Valley-Upper Hood River Valley-
Western Columbia River Gorge.
Fire Weather Watch from late Saturday night through Monday
morning for Mt. Hood National Forest West of Cascade Crest-
North Oregon Cascade Foothills.
Excessive Heat Warning from 11 AM to 9 PM PDT Sunday for North
Oregon Coast.
WA...Excessive Heat Warning from 10 AM Saturday to 11 PM PDT Monday
for Central Columbia River Gorge-Greater Vancouver Area-I-
5 Corridor in Cowlitz County-South Washington Cascade
Foothills-South Washington Cascades-Western Columbia River
Gorge-Willapa Hills.
Fire Weather Watch from late Saturday night through Monday
morning for Extreme South Washington Cascades and
Foothills.
Excessive Heat Warning from 11 AM to 9 PM PDT Sunday for South
Washington Coast.
PZ...None.
&&
$$
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AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
955 PM EDT Fri Jun 25 2021
.SYNOPSIS...
An inland penetrating coastal front will dissipate
as it moves across central NC tonight. High pressure centered
across the western Atlantic will extend into the middle Atlantic
through the beginning of the workweek. A warm and humid
southeasterly flow will develop across the Southeast.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 955 PM Friday...
Evening surface analysis shows the westward advancing coastal
front/surface trough moving across the U.S. route 1 area toward the
western Piedmont. Dewpoints vary considerably across the boundary
with TD`s in the lower 60s across the western Piedmont to the lower
70s across the eastern Piedmont. Not surprisingly, a stable air mass
is in place west of the U.S. route 1 with MLCAPE values ranging
around a few hundred across the far eastern Piedmont and Coastal
Plain.
Scattered showers and a few embedded storms earlier this evening
driven by local forcing near the boundary has largely dissipated
during the past couple of hours. However, convection has been more
stubborn and even redeveloped across the coastal areas during the
past two hours as a mid-level shear axis combined with weak
instability is producing some scattered showers. These showers are
entering Wayne and Johnston Counties this hour with more numerous
showers toward Jacksonville and New Bern. Some high res guidance
including the HRRR note that this scattered convection will persist
and advance northwest over the next few hours. Expect a lull a
little after midnight with scattered convection redeveloping across
the Coast toward daybreak with some patchy rain possible in the
western Piedmont. otherwise, partly to mostly cloudy skies will
given way to widespread stratus overnight. Lows will range in the
mid 60s across the drier western Piedmont to around 70 in the
eastern Piedmont and Coastal Plain. -Blaes
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
As of 335 PM Friday...
A front moving in from the Atlantic coast is the main focus for rain
today, however with the front decaying over the next few hours,
there will not be a particular focus for showers and thunderstorms
tomorrow. As a result, have stuck with just chance pops across the
forecast area along a diurnal cycle, although higher chances remain
across eastern counties with greater moisture present. Cloud cover
should also not be quite as thick as today, which should allow high
temperatures to be more uniform, even if the values are still below
normal, in the mid 80s. Low temperatures will not change too much
from tonight, with values in the upper 60s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 320 PM Friday...
The upper ridge offshore will gradually strengthen and migrate
southward toward Bermuda next week, resulting in a period of
slightly above normal temperatures along with a chance of diurnally
driven/weakly forced convection. Sunday will start off with a 592dm
upper ridge off the Delmarva coast with weak dry advection in the
mid levels across NC. PW`s, while still above normal, will gradually
fall from 1.9 inches in the morning to nearly 1.4 inches by late
afternoon. Any convection that develops along the sea breeze and
moves inland should dissipate quickly given increasing subsidence,
dry air aloft, and 5-10 kts of deep layer shear and it would seem
that 15-20 PoPs across the Coastal Plain should capture things
appropriately. Monday will see a similar scenario play out as the
upper ridge moves even farther south (while strengthening) with
little in the way of synoptic support for long lived convection.
GFS/EC suggest a weak inverted wave and plume of moisture will move
into the southern part of NC late Monday but this feature should be
far enough south to be of minimal concern.
Tuesday through Thursday will see southeasterly flow take hold over
the area, with steadily increasing amounts of deep moisture advected
into the Piedmont. Scattered afternoon showers and storms, with a
focus across the Coastal Plain where afternoon instability will be
maximized up to 300-500 J/kG, should be a recurring theme each day.
Meanwhile across the northern Plains, a deepening upper low and
associated surface cold front will slowly make its way toward the
Appalachians during the week and will eventually move through the
area. Not surprisingly, the timing of this front continues to slow
down given the strength and position of the offshore ridge and the
closed off nature of the low. Until the upper ridge can weaken
sufficiently or migrate away from the area, the cold frontal passage
will be delayed. Diurnally driven convection will once again be
favored on Friday, with at least some emphasis near the mountains in
addition to the Coastal Plain as increased moisture is drawn
northward ahead of the approaching front.
As for temperatures, highs in the lower 90s along with lows in the
low 70s will be common area-wide. A very climo-like pattern.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 815 PM Friday...
An inland advancing coastal front will advance across the
Piedmont this evening and begin to dissipate overnight.
Scattered showers and thunderstorms near the boundary this
afternoon will continue to dissipate and become less numerous.
Outside of lingering showers, most locations across central NC
will have VFR conditions this evening with areas of stratus and
CIGS around 4-6kft.
Overnight, expect widespread low MVFR stratus to develop after
midnight with CIGs falling into the IFR range by 7 to 11Z with
areas of MVFR fog as well. The stratus will slowly lift on
Saturday with VFR conditions in most locations by midday before
another round of scattered showers and storms develop on
Saturday afternoon. Light northeast to easterly winds less than
7kts are expected overnight with light southerly winds on
Saturday.
Outlook: Scattered showers and storms on Saturday afternoon will
dissipate on Saturday evening. Expect late night and daybreak
stratus and fog from Sunday morning through mid week. Chances of
afternoon and evening storms will be more limited on Sunday
through Monday with increasing chances on Tuesday through
Wednesday. -Blaes
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Blaes
NEAR TERM...Blaes
SHORT TERM...Green
LONG TERM...DL
AVIATION...Blaes
Area Forecast Discussion
National Weather Service Riverton WY
407 PM MDT Fri Jun 25 2021
.SHORT TERM...This evening through Saturday night
Issued at 311 PM MDT Fri Jun 25 2021
Great precipitation event for many areas the past 24 hours across
western and central Wyoming, along with much cooler temperatures
and breezy north wind. Areas from the Lander Foothills eastward to
Natrona County picked up between half and one inch, with a couple
of reports over an inch around Casper. The primary area of
stratiform rain has moved to southeast WY this afternoon as the
trough axis also moves SE. Unstable moist northerly flow follows
the trough, with scattered showers and thunderstorms developing
just after 10am this morning, mainly over the mountains and
southwest WY. So far, high resolution models are doing a good job
of highlighting the initiation and transport areas, which are over
the mountains and to the SSE over the foothills and basins. The
storms today are not expected to be severe, although the slightly
stronger ones should produce brief heavy rain with some small hail
and frequent lightning. Outflow winds over 30 mph are also
possible. Most of the convective activity should end around
sunset, though the HRRR and GFS are suggesting some enhanced
activity across central WY from sunset through about 3am.
Temperatures today are mostly well below normal for late June,
which is a nice reprieve from the heat of last week.
With the trough axis moving to western NE into eastern CO
overnight, and the large ridge over the Pacific Northwest
developing, WY will stay in cool northerly flow on Saturday. The
nose of a strong jet will also be pushing southward into WY. As a
result, Saturday will see stronger northerly flow over the area,
continued cool temps, and more scattered showers with isolated
thunderstorms. The convective activity is expected to primarily be
along and east of the continental divide. More widespread
storminess should occur over the Bighorns and Johnson and Natrona
Counties. Areas near the Bighorns could see amounts around 0.25"
with the stronger storms. The showers and storms should diminish
between 6 and 8 pm Saturday evening. The surface pressure gradient
also adjust for more of a east-northeast surface flow Saturday
night into Sunday morning with the cool air continuing to be
banked up in eastern and central WY. Southwest WY will be treated
to cool easterly flow Saturday evening.
.LONG TERM...Sunday through Friday
Issued at 311 PM MDT Fri Jun 25 2021
North flow will dominate much of the long term forecast as a
persistent high rotates off the northwest CONUS and a trough stays
to our east. Sunday will remain cool, and with some upper jet energy
across eastern Wyoming there will likely be another round of
scattered showers and thunderstorms east of the Divide. The best
chance Sunday appears to be across Johnson and Natrona counties
where the best upper level support will be realized. A warming trend
will begin Monday, with only isolated activity looking likely again
across eastern areas. Tuesday through the end of the week will be
warmer as the high builds east toward the area. Most of the area
will remain dry, although isolated convection is possible during the
afternoons. The warming temperatures may be the main story next
week, as well above normal highs look to return to the area by
Wednesday.
&&
.AVIATION...For the 00Z TAFS through 00Z Sunday
Scattered showers and thunderstorms will continue this evening,
gradually decreasing through around 06Z. Mainly VFR conditions are
expected, but local MVFR ceilings will be possible with heavier
activity including around any thunderstorms. Isolated shower and
thunderstorm activity is again expected late Saturday morning and
afternoon. A gusty north wind is expected at KRKS and terminals east
of the Divide Saturday afternoon, gusting 25 to 30+ kts at times.
&&
.FIRE WEATHER...
Issued AT 311 PM MDT Fri Jun 25 2021
A cool moist flow pattern has established over western and central
WY with some areas receiving significant precipitation over the
past 24 hours. Scattered showers and thunderstorms will continue
this afternoon into the evening hours. The storms will produce
brief heavy rain, frequent lightning, and gusty outflow over 30
mph. The storms are primarily forming along and to the SE of
mountains and moving to the SSE. They will mostly dissipate by
sunset, though there is a chance of continued showers and
thunderstorms over central WY overnight. Humidities will again
recover quite nicely overnight with light to breezy north wind.
Saturday will again see scattered showers with isolated
thunderstorms with cool north wind. The storms Saturday will
mostly be along and east of the divide, with more widespread
storms over Johnson and Natrona Counties. Temperatures will again
be below normal, though warming somewhat across western WY. Cool
conditions continue Sunday with a general east wind, with warming
and drying from the northwest starting on Monday.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...McDonald
LONG TERM...Myers
AVIATION...Myers
FIRE WEATHER...McDonald
Area Forecast Discussion
National Weather Service San Angelo TX
602 PM CDT Fri Jun 25 2021
...New AVIATION...
.SHORT TERM...
(This evening through Saturday)
Issued at 148 PM CDT Fri Jun 25 2021
Showers and thunderstorms are forecast to develop along the dryline
this evening across the South Plains/northern Permian Basin. Most of
this activity is forecast to dissipate before moving into our
forecast area, but a few storms could approach our northwest
counties late this evening. Otherwise expect mainly dry conditions
overnight. Low temperatures will be in the low to mid 70s. Expect
south winds of 10 to 15 mph to remain gusty through the overnight
period.
On Saturday, another hot day is forecast, with highs in the mid to
upper 90s. By late afternoon, a cold front will move into north
Texas while a dryline sharpens across the Trans-Pecos region.
Isolated to scattered showers and thunderstorms are forecast to
develop to our west, along the dryline, with additional storms
developing along the cold front. Most of this activity should remain
north and west of the area through tomorrow afternoon, with better
rain chances during the evening hours. A few storms could approach
our western/northern counties late in the afternoon, so have
continued slight chance/chance PoPs for these areas. A few strong to
severe thunderstorms will be possible, with large hail and damaging
winds being the main hazards.
&&
.LONG TERM...
(Saturday night through next Friday)
Issued at 210 PM CDT Fri Jun 25 2021
A well-advertised pattern change looks to set in starting Saturday
night and continuing through much of next week. After weeks of
large-scale ridging, a trough will set up over the northern Plains
and put much of the south-central US in southwest flow aloft. As
this feature develops, a cold front will push southward through the
Panhandle and stall over northwest Texas by Sunday morning. An axis
of moisture with PWATs of 1.5-2.0 inches will likely set up over
northwest Texas on Sunday, which should increase rain chances across
western portions of the Big Country. As we get into Monday, a weak
upper low over south Texas will merge with the northern Plains
trough. This should bring more moisture in from the gulf, allowing
PWATs to climb above 1.5 inches area-wide. Cloud-cover will
increase significantly, along with chances for rain on Monday
through Tuesday. High temperatures will be held down to the low to
mid 80s during this time due to persistent cloud cover and rain
chances. While rain chances will be higher these days, it is
important to remember that the amounts will still be fairly low.
For the second half of next week, the upper-level trough will
elongate and and shift slightly eastward over the Upper Midwest and
Great Lakes. But the base of the trough will still be over northern
and western Texas. So while rain chances will decrease slightly, we
are still looking at a continuing cloudy pattern with temperatures
below normal.
&&
.AVIATION...
(00Z TAFS)
Issued at 558 PM CDT Fri Jun 25 2021
Convection continues much farther west across the Permian Basin,
but latest models like the HRRR show these storms dissipating
before reaching near any of the terminal locations. Will leave
dry for now and watch radar. Otherwise, VFR conditions this
evening and into the overnight hours once again. MVFR cigs will
redevelop later tonight across the southern terminals and may
approach KSJT shortly after sunrise. Low clouds break up and lift
by late morning and leave VFR conditions. Gusty south winds will
continue tonight and through Saturday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 74 95 70 85 / 5 10 50 50
San Angelo 73 98 71 92 / 5 5 30 30
Junction 73 95 71 92 / 0 0 5 20
Brownwood 73 95 72 90 / 0 0 20 30
Sweetwater 74 94 68 82 / 10 20 60 50
Ozona 73 94 70 90 / 5 5 20 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Daniels
LONG TERM....SK
AVIATION...07
Area Forecast Discussion
National Weather Service Tulsa OK
955 PM CDT Fri Jun 25 2021
...UPDATE...
.DISCUSSION...
Currently watching two convective systems approaching the
forecast area, albeit slowly, one about a county to the north
across southern Kansas and another in western Oklahoma. Regarding
the Kansas system, although it is likely that it will affect at
least the northern tier of counties in northeast Oklahoma late
this evening or early tomorrow morning, there remains uncertainty
as to how far south it moves into the forecast area before it
decays. One thing to note, with as slow as this system`s movement
is, if it doesn`t diminish as quickly as expected, heavy rain and
flooding would become a problem sooner rather than later.
The western system appears more likely to affect a bigger chunk
of northeast Oklahoma toward and after midnight. Instability
remains high across much of the area, but wind shear is notably
less than locations to the west. As such, while an isolated severe
storm will remain possible, the expectation of organized severe
weather continues to be low.
Notable changes to the going forecast were to adjust POPs largely
for increased timing specificity but also to reduce them some in
northwest Arkansas, to increase forecast rainfall after midnight
along the Kansas border, and also to decrease low temperatures
slightly across parts of northeast Oklahoma.
&&
.PREV DISCUSSION... /Issued 627 PM CDT Fri Jun 25 2021/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Convection over ern TX Panhandle/wrn OK expected to develop eastward
this evening, with impacts expected at nern OK sites after 06z.
Included wind gusts to 35 kt and MVFR cigs/vsbys with that activity.
Low clouds again expected across nwrn AR sites late tonight, with a
chance the convection affects XNA/ROG/FYV after 12z. MLC/FSM likely
remain VFR, and south of any thunderstorm activity through this
forecast period. Multiple rounds of convection possible this
forecast period nern OK sites, and timing is problematic, but most
likely redevelopment in afternoon along frontal boundary that is
expected to sag into the area.
PREV DISCUSSION... /Issued 306 PM CDT Fri Jun 25 2021/
DISCUSSION...
Showers and thunderstorms have developed near a frontal boundary
across Kansas this afternoon. This activity is expected to
continue to organize, and begin to push southeast towards and into
our area later this evening and overnight. The latest HRRR is
quite aggressive with the southward progression overnight, and
certainly cannot rule this out. For now, will keep the higher pops
confined to northeast Oklahoma, with lower pops as far south as
McAlester and Fort Smith.
Early day convection will gradually wane by midday Saturday, with
renewed development expected by late afternoon along the frontal
boundary, which by that time should be near the northwest part of
our area. Locally heavy rainfall amounts will be more likely
Saturday evening, so a flood watch may be needed by that time,
especially if significant rainfall occurs tonight.
The frontal boundary will likely sag very slowly south with time,
as an upper trough remains in place just to our west. This will
keep shower and thunderstorm chances going through much of next
week, with the potential for locally heavy rainfall. The trend
will be for the heavier rainfall to slowly shift to the south and
east with time.
With all the clouds and rain, high temperatures will be several
degrees below normal for most of the next week.
Stayed close to the National Blend of Models forecast.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...22