Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/22/24
Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Wed Aug 21 2024
.KEY MESSAGES...
- There is a slight risk (level 2 of 5) for severe weather
across western and parts of central North Dakota this evening
and overnight, with medium to high chances (40 to 75%) for
showers and thunderstorms during the same time period.
- Temperatures are forecast to warm from Thursday into the
weekend, with highs in the mid 80s to mid 90s on Saturday.
&&
.UPDATE...
Issued at 946 PM CDT Wed Aug 21 2024
We continue to monitor severe storms over eastern Montana that
are slowly approaching western ND. It looked like they may have
been trying to better organize but latest radar trends don`t
appear to be supporting that. Once again for the forecast there
were no major changes. There were some minor adjustments to POPS
for timing and coverage. The forecast still brings the area of
convection into ND as the upper level shortwave continues to
approach, with the convection progressing eastward and out of
our CWA by tomorrow morning. With ample instability still in
place along with 0-6 km shear around 40kts and a low level jet
at play (850mb winds from the south around 30-40 kts), there is
still the risk of strong to isolated severe storms overnight.
UPDATE
Issued at 653 PM CDT Wed Aug 21 2024
No significant changes were made with this update. Satellite
imagery continues to show widespread low stratus hanging on over
approximately the eastern half of the state. The expectation
with regard to strong/severe storm potential, especially over
western ND, remains the same as well. Currently we have a
Severe Thunderstorm Watch just to our southwest stretching
across portions of MT and SD. Latest SPC mesoscale discussion
mentions possible expansion of the Watch into western ND. Latest
SPC mesoscale analysis continues to show 2000-3000 kg/J of CAPE
over western ND with 0-6km shear generally around 40kts and
expected to increase with the approaching wave. Latest HRRR
continues to show a fair amount of CIN in place, including
western ND, which may aid keeping storms in check at least
initially. Storms have been relatively slow to develop to our
west, but expect more activity as the upper level shortwave
continues to approach the region.
&&
.DISCUSSION...
Issued at 304 PM CDT Wed Aug 21 2024
This afternoon, the synoptic pattern across the CONUS was
characterized by omega blocking, with the central ridge just
east of the forecast area leading to southwest flow over the
Dakotas. An embedded shortwave was rounding the base of the
western trough, passing over the Northern Rockies, with a
deepening surface low in north central Wyoming. An attendant
surface trough was oriented generally north-south with the low,
with a cold front to the northwest of the surface trough. Low-
level warm air advection was overspreading eastern Montana and
western North Dakota ahead of the incoming wave, although
plentiful moisture in the southeasterly surface flow has led to
persistent low cloud cover across much of southern and central
North Dakota, as well as northern South Dakota. Daytime
satellite imagery shows mostly clear skies across eastern
Montana into Wyoming, with signs of somewhat agitated cumulus
developing in these areas.
The general expectation is that as the shortwave approaches and
heights fall ahead of the trough base, scattered convection will
develop off of the higher terrain in Montana and move east
towards the forecast area. The current environment in eastern
Montana into western North Dakota is characterized (per SPC
mesoanalysis) by 2000-3000 J/kg of MUCAPE, steep mid-level lapse
rates, and bulk shear on the order of 30-40 knots. Dew points
and subsequent instability increase to the east across this
focus area before dropping off across central North Dakota,
especially now that cloud cover has been so persistent. Our
thinking is that shear will increase through the evening and
into tonight with the approaching wave, with the addition of a
low-level jet kicking in late this evening. Capping is certainly
a concern when it comes to the threat ceiling, as well as storm
mode, which we are uncertain of. High-res guidance has been
changing pretty consistently over the past few cycles. If storms
end up staying more discrete, will likely be a larger hail
threat, but there have been some signs of a more
multicell/cluster storm mode with deep layer flow more parallel
than perpendicular to the surface trough. Although DCAPE is
over 1000 J/kg across western ND, 0-3 km shear is forecast to
generally stay under 25 knots, and there is low confidence in a
linear storm mode. We did discuss messaging a higher wind threat
than 60 mph, as there has been some mention of higher magnitude
wind potential over western North Dakota, but we feel as though
this is a rather isolated threat and will be primarily focused
over eastern Montana. SPC did expand our Slight Risk (level 2
out of 5) earlier today, which seems fair given the expanded
area of favorable overlap compared to what previous guidance was
advertising.
What has been consistent in CAMs is for an initial push of
convection in southwest North Dakota this evening, before the
main area moves in from Montana late this evening into the
overnight hours. If we don`t see more clearing in the southwest
part of the state over the next few hours, capping concerns come
into play which could keep convection sub-severe. Blended
guidance has sped up precipitation timing just a bit through the
night, with showers and thunderstorms entering northwest North
Dakota in the late evening, quickly expanding east through the
forecast area and ending in the James River Valley Thursday
morning. With the faster timing, our Marginal Risk (level 1 out
of 5) has been significantly trimmed back which seems quite
fair, given the bulk of precipitation should be out of the
forecast area before we can get much in terms of heating and
instability. However, it will be dependent on how things
progress overnight, and we will still likely have scattered
showers and thunderstorms across the area, but it is more likely
they will stay sub-severe.
After storms clear out on Thursday, skies will clear from west
to east as well, with highs mainly in the 80s. We begin a modest
warm up through the end of the week as flow is generally zonal,
with a shallow ridge building in downstream of a deepening
trough over the western CONUS. Highs will peak on Saturday in
the mid 80s to mid 90s, with low but non-zero chances for
showers and thunderstorms on Friday and Saturday.
The general trend has been for the aforementioned trough to move
into the central CONUS to start next week, although there are
differences in timing among ensemble clusters. Regardless,
blended guidance is showing cooler temperatures and increased
chances for precipitation to start the work week, with a
potential additional cooldown late next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 653 PM CDT Wed Aug 21 2024
A low stratus deck continues to bring MVFR conditions to KBIS
and KJMS. Satellite imagery indicates this should continue, with
a slight westward expansion of the clouds evident. We continue
to expect showers and thunderstorms to spread into western ND
and progress eastward. Given uncertainties in coverage and
timing, the forecast continues to carry VCTS for all terminals.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...JNS
DISCUSSION...Jones
AVIATION...JNS
Area Forecast Discussion
National Weather Service State College PA
1125 PM EDT Wed Aug 21 2024
.SYNOPSIS...
*Early taste of Fall fades with seasonal warmup by the weekend
*Summertime conditions return for the last week of August
&&
.NEAR TERM /THROUGH THURSDAY/...
Lake clouds and residual remnant clouds from earlier light shra
extend from the NW Mountains to the Lower Susq late this
evening. These will continue to entrain and decrease through 06z
with most areas becoming clear to partly cloudy for the balance
of the overnight.
Clearing skies, dry/low pwat air and light winds associated
with surface high pressure will result in another unusually
cool night by August standards. We continued to trend min temps
toward a blend of persistence (last night`s obs) and below the
25%tile NBM. Air/water spreads and synoptic setup will also be
favorable for fog development particularly in the north central
river/stream valleys.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Improving conditions start Thu as the upper low begins to lift
as 1024+mb sfc high slides over PA. This will translate into
dry weather and decreasing NW breeze. Partly to mostly sunny
skies with max temps in the upper 60s to mid 70s trend warmer
day/day, but remain 5-10 degrees below late August climo.
Another seasonably chilly night on tap for Thursday night
with nearly ideal radiational cooling under the center of the
surface high. This signal also supports more valley fog into
early Friday morning.
Summertime conditions then make a comeback by late week and into
the weekend, with a warmer return southerly flow developing
Friday as the high slips off of the East Coast. Expect min temps
to begin a series of higher lows with max temps trending near
to above the historical average into the upper 70s to mid 80s by
the weekend.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Humidity and temperatures continue to increase throughout this
weekend thanks to southerly return flow behind retreating high
pressure. We could see an isolated shower into the middle of
next week, but most of the time should remain dry.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
03Z Update...Forecast generally remains on track, although have
added SCT003 decks in the 08-12Z timeframe at BFD/IPT/UNV with
calm winds at these locations and generally SKC conditions. RAP
model soundings are tracking closely but generally keep lower
levels just dry enough to dissuade from adding FG mentions at
this time so have kept mentions out of the TAFs at this time due
to lower confidence.
Previous Discussion (Issued 7:29PM EDT 8/21/2024)...
A broken-to-overcast deck between 5-8kft AGL will continue over
the next hour (or two) before becoming more scattered in nature
after 03Z Thursday. The light showers across east-central PA
have generally tapered off and do not expect any SHRA mentions
through 00Z Friday. There is moderate (50-60%) confidence in
prevailing VFR continuing through 00Z Friday at all airfields
outside of BFD/IPT/UNV.
Clearing skies overnight with winds dropping off (light and
variable to near calm between 07-12Z Thursday) will lead to
patchy valley fog formation with slightly higher confidence
closer to IPT/UNV than BFD. The main concern with fog formation
will be some lower- level dry air outlined in model RAP
soundings that could limit this potential. At this time, have
kept mentions to VCFG for these airfields although subsequent
TAF packages might have higher confidence to include visibility
and/or ceiling restrictions.
After any (potential) fog mixes out in the 13-14Z Thursday
timeframe, expect VFR conditions to prevail through 00Z Friday
with high (> 90%) confidence. Cloud coverage does not look to be
as widespread on Friday, but a broken 6-8kft AGL ceiling with
gusts in the 15-20KT range appear possible through the PM hours.
Outlook...
Fri-Sun...Patchy AM fog; otherwise, VFR w/ no sig wx.
Mon...Mainly VFR. Isolated PM SHRA/TSRA possible NE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Fitzgerald/Steinbugl
SHORT TERM...DeVoir/Fitzgerald/Steinbugl
LONG TERM...DeVoir/Banghoff/Gartner/RXR
AVIATION...NPB
Area Forecast Discussion
National Weather Service Cheyenne WY
951 PM MDT Wed Aug 21 2024
.KEY MESSAGES...
- Scattered to numerous showers and thunderstorms are expected
on a daily basis for the foreseeable future, some with locally
heavy rainfall. Isolated strong to severe thunderstorms will
be possible at times as well.
- A drying trend will arrive by Sunday with the potential for
increased risks of Fire Weather concerns through early next
week.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 257 PM MDT Wed Aug 21 2024
Today and tomorrow will feature active weather over southeast
Wyoming and western Nebraska. A classic monsoon pattern is evident
over the southwestern CONUS with a ridge of high pressure in place
and seasonably high PWAT values around 1-2 standard deviations above
the normal. Forecast soundings this afternoon indicate that much of
that moisture is above a deeply mixed boundary layer present
anywhere along and west of I-25. Deep inverted-V soundings generally
favor strong wind gust potential and that threat will be present
especially if any stronger storm cores can form over higher terrain
and descend eastward through the afternoon and evening hours. There
is also a dry lightning threat given large T/Td spreads at the
surface, highlighted as well by the SPC Astride outlook over
east- central Wyoming today. Farther east and south over far
southern Wyoming and into the Nebraska Panhandle, a very modest
amount of west-southwest mid and upper-level flow is present
resulting in bulk shear values in the 20-30 knot range. Given
this weak shear overlap with better surface moisture (Tds in the
mid to upper 50s) and SBCAPE values near 2000 in the NE
panhandle, one or two severe thunderstorms are possible later
this afternoon after any MLCIN is eroded. CAM guidance supports
the idea of eastward propagation of any convection which will
likely end before around 8pm this evening. Overnight, expect
more mild temperatures with scattered to broken cloud ceilings
helping to prevent better radiational cooling.
A very similar setup is expected on Thursday over southeast Wyoming
and western Nebraska. Convection is first expected to initiate over
the higher terrain of the Snowy, Sierra Madre, and Laramie ranges by
19z or so and spread eastward throughout the afternoon. Height rises
at 500mb and associated warming mid-level temperatures will help
sustain capping throughout the early afternoon, perhaps resulting in
a bit weaker convection east of I-25. However, a subtle vort
max/weak wave of faster flow aloft moving through by sunset may help
touch off a few storms farther east in the NE panhandle. Cloud cover
should help reduce afternoon highs somewhat from past days. Overall,
HREF ensemble guidance is in good agreement through the forecast
period. Primary adjustments to the forecast on Wednesday and
Thursday were to raise overnight low temperatures given the cloud
cover forecast and nudge PoP values slightly upward.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 257 PM MDT Wed Aug 21 2024
The monsoonal pattern is expected to continue with plenty of
moisture. With a southwesterly flow, Carbon and Albany county could
begin to see a slight chance of scattered thunderstorms after noon.
Convection could then spread east to the rest of southeast Wyoming.
The Nebraska panhandle seems to look pretty dry until 6 p.m, when
scattered storms could impact the area. So far, the chances of these
storms impacting the CWA being severe is on the lower side due to
minimal wind shear, though not impossible.
Minimum temperatures look to hover in the mid 60s in the Nebraska
Panhandle and upper 50s to low 60s in Southeast Wyoming. The
higher elevations of the Medicine Bow and Sierra Madre Mountain
ranges have an 80% chance of seeing minimum temperatures in the low
to mid 40s. As for maximum temperatures, the mountainous areas will
likely see highs into mid to upper 50s. Carbon and Albany county
will see cooler temperatures than the rest of the CWA around the
upper 70s, with the rest of southeast Wyoming and the Nebraska
Panhandle seeing upper 80s and low 90s.
The weekend forecast will center around a trough of low pressure
moving through the northwest CONUS and how it interacts with
residual monsoonal moisture to the south. As of the 12z ensemble
guidance cycle today, southwest flow aloft will increase on
Saturday and Sunday as this trough approaches. Forecast
guidance indicates that the majority of deeper surface moisture
will be shunted eastward into the high plains, east of the NE
panhandle thus limiting the overall threat of severe weather
despite better wind shear/flow aloft. However, if the speed of
this trough slows enough, Saturday afternoon could feature a
more robust severe threat in the eastern plains/NE panhandle if
enough surface moisture/upslope surface flow can remain in
place. By Sunday, most ensemble members drive a hot, dry and
deeply mixed southwesterly flow environment over the entire CWA
resulting in a mainly dry day. Fire weather/Red Flag concerns
may become relevant on both days if RH values can remain below
20%. Dry weather will continue on Monday and Tuesday over
southeast Wyoming and western Nebraska as a westerly flow regime
remains in place. Expect temperatures to remain above average
through the period. Forecast confidence remains high through the
long term with slight adjustments made to PoP grids during the
afternoon hours.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 946 PM MDT Wed Aug 21 2024
Concerns for the 06Z TAFs deal with low stratus in the Panhandle
Thursday morning. KAIA and KSNY did get quite a bit of rainfall
this evening...which will help with low level moisture. Latest
HRRR guidance showing possible IFR/LIFR ceilings at both
airports around 12Z tomorrow morning. Decided to bring KAIA and
KSNY down to 500 foot ceilings 12Z to 15Z. Then showers and
storms Thursday afternoon for most airports. Maybe not as
numerous as Wednesday...but the threat is still there.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MAC
LONG TERM...MN/MAC
AVIATION...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
509 PM CDT Wed Aug 21 2024
...Updated Aviation...
.KEY MESSAGES...
- Showers and sub-severe thunderstorms are likely tonight along
and north of KS-96.
- Another round of showers and thunderstorms is possible
tomorrow evening into the overnight, which may be marginally
severe.
- Afternoon temperatures in the 100-105 range are expected on
Saturday.
&&
.DISCUSSION...
Issued at 200 PM CDT Wed Aug 21 2024
No change to the short term forecast this cycle as southwest KS
remains under the influence of a mid-level cut-off ridge
centered over the southern and central plains, with a pair of
troughs on either side as per latest water vapor satellite
imagery and RAP analysis. At the surface, temperatures have
warmed into the 80s for most areas, save for roughly the central
third of our CWA where a stratus deck was in place much of the
morning. Visible satellite shows this deck has mixed out
completely, with full sunshine now common which will support
afternoon highs in the upper 80s to upper 90s. Tonight into the
early morning hours, HREF members indicate scattered showers
and thunderstorms are likely along and north of KS-96, as
probability of QPF > 0.01" is in the 60-80% range. Any
thunderstorms will be sub-severe as proximity to the mid-level
ridge will foster insufficient deep-layer shear.
Daytime Thursday, short range ensembles suggest the warming
trend will continue as the mid-level ridge inches eastward.
850-mb temperatures are expected to warm by 2-3C owing to strong
subsidence under the ridge, which will translate to afternoon
highs in the low 90s to near 100. Another round of showers and
thunderstorms is possible during the late afternoon into the
overnight hours favoring the northwest and northern zones as a
weak mid-level vorticity max ejects from the Rockies onto the
central plains, with HREF probability of QPF > 0.01" in the
30-50% range. Similar to Wednesday, weak flow aloft will limit
severe potential, however, the ejecting perturbation may support
just enough H5 flow to result in some degree of storm
organization, and a brief marginally severe wind gust or
hailstone cannot be ruled out.
Friday through the weekend and into early next week, medium
range ensembles agree the mid-level ridge will stay mostly
stationary while expanding. This pattern will lead to a
continuation of the hot and mostly dry conditions across
southwest KS, with Saturday currently appearing to be the
hottest with afternoon highs in the 100-105 range. It is not
impossible that a few stray showers and/or thunderstorms
propagate through the northwest to northern zones during this
time period as LREF probability of QPF > 0.01" is in the 10-30%
range, but strong subsidence under the mid-level ridge will
yield very spotty coverage, and the dry forecast (<15% pops) was
maintained.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 509 PM CDT Wed Aug 21 2024
Good flying weather will continue through this TAF period, with
VFR persisting and scattered cirrus. Many models do not develop
scattered thunderstorms near HYS overnight through Thursday
morning, so opted to keep the HYS TAF dry for now. Light
southeast winds will continue to prevail at 9-14 kts. After
15z Thu, SE wind gusts of 20-25 kts are expected at all
airports.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Springer
AVIATION...Turner
Area Forecast Discussion
National Weather Service Des Moines IA
649 PM CDT Wed Aug 21 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Mainly dry through Thursday, with low chance for rain/weak storms
Friday morning northwest
- Additional chances for showers and storms this weekend
- Warmer temperatures arriving this weekend into early next
week, especially Sunday/Monday
&&
.DISCUSSION...
Issued at 237 PM CDT Wed Aug 21 2024
Outside of the lingering light rain showers this morning that have
since diminished, the overall weather pattern has changed very
little, with surface analysis showing the large area of high
pressure remaining over the Upper Midwest, while a weak low pressure
system sits over Wyoming and Montana. Following the drying
conditions, cloud cover has also been decreasing, with the majority
of any remaining clouds over western Iowa while the remainder of the
state sees broken areas of upper level clouds in an otherwise mostly
sunny sky. Surface southeast flow has remained light, with some
gusts around 15 mph but overall fairly comfortable this afternoon as
temperatures sit in the upper 60s to low 70s. With increased
sunshine and low level southwest flow, temperatures will
continue to increase with highs reaching into the upper 70s.
Upper level ridging across the western CONUS will continue to
slowly track eastward over the next several days, though several
waves riding the ridge look to move into the Central Plains
during this time, which could lead to periods of showers and
possibly some storms.
The first is a shortwave and associated surface boundary extending
into the Dakotas and Nebraska tracking east/northeast into the
region late this evening into Thursday, though the general consensus
among models is a weakening trend as it nears Iowa, mainly due to
limited forcing and low level dry air as seen per model soundings.
This will lead to continued dry conditions throughout Thursday, with
breezy southeast winds and highs once again reaching into the upper
70s to low 80s into the afternoon. Another wave approaching Iowa
into Friday morning from the Intermountain West looks to hold a
somewhat better potential for showers and possibly a few weak
storms. Even so, similar trends with less favorable forcing and
lingering low level dry air per soundings from the HRRR, RAP and
GFS, despite the more saturated profile per the NAM are more looking
more likely to occur at this time, so the overall chances are rather
low. Coverage over Iowa also varies among models as a result of
these differences, though most generally keep much of the activity
over the northwest half of the state, with fairly low-end rain
amounts.
Into the weekend, the thermal ridge will move over the Central
Plains, which will send much warmer temperatures over the area into
early next week. Temperatures in the 20s at the 850mb level with
mostly clear skies Sunday into Monday will likely allow for
favorable mixing to lead to surface temperatures reaching into the
90s, along with slightly breezy conditions. Increased instability
with additional waves passing through look to bring additional
chances for showers and storms both Saturday and Sunday, though
timing and placement is more uncertain given timing ahead of this
activity, so will be keeping an eye on it over the next several
forecast cycles.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 630 PM CDT Wed Aug 21 2024
VFR conditions are expected to continue through the TAF period.
High clouds increase especially west overnight into Thursday,
but will generally be of little impact. Winds out of the
southeast remain lighter overnight but turn more southerly and
increase through the afternoon hours Thursday, the highest gusts
in the northwest with gusts of 20-25 knots.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Bury
AVIATION...KCM
Area Forecast Discussion
National Weather Service Gray ME
1024 PM EDT Wed Aug 21 2024
.SYNOPSIS...
An upper low slowly moves eastward tonight continuing showers
that may become heavy at times. Localized flooding is possible,
especially in the higher terrain. The recent cool and unsettled
pattern will continue through Thursday before the stubborn low
pressure system slowly lifts out of the region with a drying and
warming trend expected through the weekend. A cold front will
usher in a return to somewhat cooler weather early next week
along with a few showers and thunderstorms.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Update...
Have updated pops based on current radar imagery and latest
HRRR. Showers will continue exit central areas and become
situated over the mountains for the remainder of the night.
Patchy fog to develop with some drizzle remaining possible as
well.
Otherwise, very little in the way of changes to the near term
portion of the forecast.
Prev Disc...The focus of the precipitation continues to be over
the north and mountains. However, latest radar imagery at 2230Z
was depicting slow moving showers over Cumberland, western
Androscoggin and eastern Oxford Counties. This precipitation
will likely train over the same areas late this evening leading
to locally heavy precipitation. The HRRR continues to indicate
heavy precipitation in the mountains this evening as well. Will
continue to monitor trends this evening.
Otherwise, only minor modifications to the near term portion of
the forecast for temperatures, dew points and cloud cover.
Prev Disc...
Impacts:
* Showers that may be heavy at times will develop tonight and
my lead to localized flooding, especially in the higher
terrain. Flash Flooding is not expected.
Latest RAP13 analysis shows the center of the upper low has
very slowly shifted eastward as expected, now over the Vermont-
New York border. We continue to see daytime instability help
blossom showers across the area. They will continue to rotate
through the area this evening as the upper low continues its
journey eastward. As always when upper lows are moving overhead,
you have to worry about showers near the pivot point as they
tend to train over areas. PWATs are less than inch and latest
CAMs are keeping these storms progressive so Flash Flooding is
not expected, but should training occur some localized flooding
is possible, especially in areas of higher terrain where runoff
contributes. SPC mesoanalysis currently analyzes around 250 J/kg
across central and southern New Hampshire, so while no
lightning has been observed thus far it is not out of the
question before this shower activity is through. With that being
said this activity should begin to taper off not long after
midnight, leaving us dry overnight. Thinning clouds, and already
cool daytime temperatures, will make for a chilly night with
lows in the low 50s across the area, with some areas of the
mountains and river valleys dropping into the upper 40s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
Impacts:
* No significant weather impacts expected.
Stacked low pressure moves overhead tomorrow which will create
a set up very similar to what we saw Wednesday. Thinning of the
cloud deck overnight will allow many places to start dry, but
this will contribute to building instability heading into the
afternoon, helping showers blossom heading into the afternoon.
With the best forcing moving out of the area, coverage and
instability will be less than today. Latest CAMs still show
areas of 100-200 J/kg of CAPE being achieved which would be
enough to develop an isolated thunderstorm. These showers will
be light, briefly heavier in a thunderstorm, so no hydro issues
are expected. High temperatures remain cool with highs in the
upper 60s to low 70s south of the mountains, and low 60s to the
north. As the upper low departs overnight, we will see clearing
skies which will allow for another chilly night in the low to
mid-50s for the area.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
High Impact Weather Potential: The potential for widespread high
impact weather is low through the long term forecast period.
--Pattern and Summary--
The primary change to the longwave pattern through the long term
portion of the forecast is reduction of blocking across the
central/eastern Pacific which will allow for an increasing Pacific
influence across much of North American next week with as the EPO
shifts positive. Closer to home...the period will open with a
cutoff low overhead /though slowly lifting away/ with good agreement
that another trough will take it/s place by the beginning of next
week. Beyond this...by the middle and latter portions of next
week...more substantial height rises reach the northeastern United
States likely moving temperatures again above normal.
A warming trend will open the forecast period through this
weekend...before temperatures settle back early next week with
the arrival of the next upper low. As for precipitation
chances... building heights to begin the period should bring an
end to the recent showery pattern with dry conditions through
the weekend. Shower chances increase again early next week as
the next upper low arrives...though the forcing suggests little
support for widespread significant rainfall. Some slow
moving...local downpours will be possible in the vicinity of the
upper low.
--Daily Details--
Friday through Sunday: Upper low lifts away from the region Friday
with building heights and warming temperatures. Surface high crests
south of the region on Saturday with a mid level shortwave ridge
overhead. By Sunday...the low/mid level flow begins to back ahead
of next approaching shortwave and associated trough diving towards
the region from Quebec. This should allow for a dry weekend across
the region with temperatures building from Friday into Saturday with
T8s around 10C Friday warming to +13-14C through the weekend. This
will result in highs building into the 70s Friday...with mid 70s to
lower 80s from north to south for Saturday-Sunday. There will be
more clouds on Sunday than Friday-Saturday with the approaching
trough with moisture increasing /PWATs reach 1"/. Outside of some
morning valley fog...no significant sensible weather is expected.
Monday through Wednesday: Conditions will turn more unsettled for
the beginning of next week with a cold front crossing the area
Sunday night before the arriving shortwave closes off overhead. The
upper pattern will be similar to what we/ve experienced this
week...though temperatures aloft will be warmer. Thus...expect daily
shower chances...with some rumbles of thunder given modest
instability. The best threat of impactful weather will come from slow
moving showers/storms, but this threat is expected to be isolated.
Current consensus high temperatures are in the mid 70s to lower 80s.
Could see these trend lower /at least for a day or two/ depending on
the details of cloud cover/shower activity as well as the exact
placement of the upper low...so kept the forecast a bit below the
National Blend of Models.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term...Light rain showers are bringing varying VFR/MVFR
decks late this afternoon, and will continue through early
tonight. Lightning is not out of the question, particularly at
CON, MHT, and PSM. While most terminals head toward VFR, LEB,
HIE, and possibly AUG and RKD may be heading toward IFR/LIFR
with fog developing. Either way, VFR will be the prevailing
condition on Thursday. Westerly winds are expected to remain
light.
Long Term...VFR conditions are expected to dominate the long
term period through Sunday. Morning fog will be possible at
HIE/LEB. A cold front will drop through the region Sunday night
with scattered showers which will bring some localized MVFR
restrictions. Winds are expected to remain light through the
period.
&&
.MARINE...
Short Term...No significant systems will be moving over the
waters over the next 48 hours so conditions will remain below
SCA criteria. Winds will remain generally westerly, with an
afternoon seabreeze likely tomorrow afternoon. Wind gusts will
be 10-15 kts.
Long Term...Winds and waves are expected to remain below SCA
levels through the long term forecast period.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR/SHORT TERM...Cannon
LONG TERM...Arnott
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
732 PM EDT Wed Aug 21 2024
.KEY MESSAGES...
- Dry with well-below normal temperatures and lower humidity
- Temperatures trending warmer with above average temperatures by
Saturday.
&&
.FORECAST UPDATE...
Issued at 732 PM EDT Wed Aug 21 2024
Previous forecast looks good and no major changes needed. 10th
percentile model blend temperatures were used, and our only
adjustment was to steepen the curve during the late evening and
early tonight, since the air mass supported a quick drop last
evening. Otherwise, satellite shows some smoke from wildfires in
Canada that aren`t represented in HRRR or RAP smoke modeling.
Limited sensible weather impact, but may scatter sunlight at sunset
some causing a redish color and slightly more white color to the
sky.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 244 PM EDT Wed Aug 21 2024
Fall-like weather will continue for the short term as central
Indiana remains under the influence of Canadian high pressure.
Latest IND ACARs sounding shows a very dry atmospheric profile with
a subsidence inversion around 850mb/1km agl. With 850mb temps well
below normal for this time of year at 7C, max surface temperatures
are only reaching the lower to mid 70s even with steep boundary
layer lapse rates. Lowered afternoon humidity levels for today and
tomorrow as deep mixing has already resulted in dew points in the
40s for most locations. Despite lower humidity, conditions are not
meeting critical thresholds for fire weather concerns.
Tonight will likely be the coolest night of the season for a few
areas, especially low lying wind sheltered locations. Optimal
conditions expected for radiational cooling as the center of the
high pressure moves over the northern half of the state tonight.
With such a dry airmass, light winds, and clear skies, decided to go
well below guidance for min temps, towards the NBM10th percentile,
with mid to upper 40s for Central and North Central Indiana and low
50s for South Central Indiana.
Almost a copy/paste forecast for Thursday as the area of high
pressure slowly begins to shift eastward. Highs may be a degree or
two warmer during the afternoon in the mid to maybe upper 70s, but
overall expect another dry, Fall-like day.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 244 PM EDT Wed Aug 21 2024
Thursday Night Through Sunday.
The stagnant weather pattern that has been in place for much of the
week will continue late this week into the weekend as a broad and
expansive ridge across the central US states is bookended by two
larger low pressure systems off each coast. The system on the west
coast will move into southern Canada with the ridge blocking most of
the eastward progression. There will be a low potential for
diurnally driven showers this weekend but soundings show a robust
cap in place along with fairly low instability and no lifting
mechanisms in place. As the ridge builds, temperatures will
gradually continue to warm, especially as the northerly flow gets
cut off by late Wednesday. Expect to see highs in the mid 80s by
Friday followed by 90 towards Sunday.
Monday Through Wednesday
The ridge will slowly begin to migrate eastwards towards early next
week which will keep the flow near the surface and aloft quite
stagnant and lead to temperatures climbing into the low to
potentially mid 90s by mid-week. A weak cold front may push through
Tuesday into Wednesday, but the forcing associated with this system
will be centered in Canada with only weak forcing towards the Ohio
Valley. Ensembles show quite a bit of difference on both the timing
and extent of precipitation, so plan on keeping POPs low until
better agreement on the system progression arrives.
By early next week, air quality may start to become a greater
concern late this weekend into early next week with the
aforementioned stagnant airmass and cap aloft leading to poor air
circulation and a buildup of ozone. Forecast dewpoints look a bit
aggressive in the models with the recent dryness combined with the
corn sweat season coming to an end, so plan on tapering those down a
bit to limit the afternoon heat indices and associated heat risk.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 632 PM EDT Wed Aug 21 2024
Impacts:
- None
Discussion:
VFR conditions will prevail. Thursday morning, a slight veering of
wind direction to more east-southeasterly is anticipated, but wind
speeds will remain light. Some smoke from Canadian wildfires is
evident on satellite but should be minimally noticable and not
impactful, relegated to the upper atmosphere. Some cumulus may again
form Thursday late morning onward.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...BRB
SHORT TERM...CM
LONG TERM...White
AVIATION...BRB
Area Forecast Discussion
National Weather Service Marquette MI
729 PM EDT Wed Aug 21 2024
.KEY MESSAGES...
- Mostly dry forecast into next week.
- Near normal temperatures round out the work week before above/much
above normal temperatures return for the weekend into next week.
- Best rain chances (20-40%) over the next 7 days will be late
Thursday night into Friday.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 129 PM EDT Wed Aug 21 2024
GOES-16 Visible imagery shows some fair weather cu over the central
and eastern portions of the UP as well as some lower marine clouds
over western Lake Superior. Apparent on satellite and in the clear
air clutter on KMQT radar reflectivity is the Lake Superior lake
breeze, with CAMs resolving that lake breeze pushing inland along
with one off of Lake Michigan this afternoon. RAP analysis shows a
closed upper high over the New Mexico/Texas border with a ridge axis
extending NE from there all the way into northwestern Ontario. With
the peak of negative vorticity advection over the Upper Great Lakes
today, the surface feature response is a ~1025mb high pressure and
pleasant weather. Expect high temperatures in the low to mid 70s
today, slightly below normal.
Overnight, expect another clear night with temperatures falling
below normal and into the 40s. As temperatures will have a bit
farther to fall tonight than previous nights, temperatures shouldn`t
hit freezing like they have in at least one location the past couple
nights. However, given the various microclimates, wouldn`t be
surprised if a typical cold spot hits the upper to mid 30s tonight.
Patchy fog is once again possible tonight, with chances for 1/2SM or
less fog highest in the east (20-40%) with ~10-20% chances
elsewhere.
Thursday, the ridge axis will move directly overhead and the surface
high will shift east to be over the southern portion of the Great
Lakes Basin. Weaker subsidence aloft will allow for even more
diurnal cu to form over the central and western UP, though virtually
every model available shows 0 precip except for the 00Z and 12Z
NSSLWRFs. Will keep 0 PoPs in the forecast until at least some
other model support comes for daytime showers. The gradual
warming trend will continue, with highs firmly in the mid to
upper 70s with a few typical warm spots ~40% likely to break 80.
CAMs also show lake breezes off the Great Lakes.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 348 PM EDT Wed Aug 21 2024
The tranquil weather over the UP will be disturbed by a weak ridge-
riding shortwave that will arrive over western Lake Superior by 00Z
Friday. LREF mean SBCAPE is around 100-200 J/kg, which is not
terribly impressive but is enough that thunder cannot be ruled out
of the forecast (~15%). While the arrival of showers is just barely
within the valid times of the HREF suite of CAMs, there are some
disagreements about the coverage of showers, ranging from isolated-
to-scattered (WRF FV3) to broad coverage (NAM Nest). With around
1.25 inches of PWAT available, a localized downpour cannot be ruled
out as maximum HREF precipitation peaks at 0.5-1.0 inch, but the
mean (and more likely) values are 0.01 to 0.25 inches. Some gustier
winds might be realized with this system as Euro ensemble mean wind
gusts on Friday are around 25 mph. Despite the cloud cover from this
shortwave inhibiting radiational warming, warmer air will be
advecting in, keeping highs on Friday near normal in the mid- to
upper-70s and locally near 80.
Following the passage of showers on Friday, the pattern beyond looks
dry, with mean LREF accumulated precipitation by next Wednesday
evening only around 0.5-1 inch. An anomalously low trough digging in
over the West Coast will help kick ridging further east, and with
the GEFS showing 500mb height anomalies exceeding +15 dam by 06Z
Monday, the UP will be in for warmer than normal temperatures. The
NBM shows widespread mid-80s with around 10% chances of some
interior UP locations exceeding 90 degrees early next week.
Conventional wisdom would indicate that a trough passing through the
Rockies should help kick a low pressure towards the UP, but the 12Z
GEFS really struggles to bring low pressure to the Upper Great
Lakes, favoring a weak surface high instead. While some occasional
diurnal showers cannot be ruled out, this forecast will lean
slightly drier than the NBM.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 728 PM EDT Wed Aug 21 2024
Much like the past few nights, high pressure over the Great Lakes
continue VFR conditions through the TAF period except for periods of
patchy FG before sunrise. Confidence is low on timing and coverage,
especially at CMX, thus opted to give IWD and SAW a TEMPO for
possible visibility drops between 06z-11z. Once day breaks and fog
clears, not looking at any forecast concerns for the rest of the
day. Winds will be light and southerly, poking a bit higher at IWD
with gusts 10-15 kts.
&&
.MARINE...
Issued at 348 PM EDT Wed Aug 21 2024
High pressure over the Great Lakes will keep wind gusts below 20 kt
through Thursday night. As a weak shortwave pushes over Lake
Superior late Thursday night through Friday, southwest wind gusts
increase to 20-25 kt between Isle Royale and the Keweenaw Peninsula
on Friday. With general broad ridging to return over the Great
Lakes, wind gusts are expected to remain below 20 kt Saturday
through the end of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...GS
LONG TERM...GS
AVIATION...BW
MARINE...GS
Area Forecast Discussion
National Weather Service San Angelo TX
618 PM CDT Wed Aug 21 2024
...New AVIATION...
.SHORT TERM...
(This evening through Thursday)
Issued at 156 PM CDT Wed Aug 21 2024
Suffice it to say this week continues to be the hottest week of
the summer for West Central Texas. As of the 2 PM hour both San
Angelo and Abilene have already broken their record highs for the
day, with the monthly record well within reach (111 degrees at
both locations set in 2023). The upper level high pressure ridge
will remain over the region tomorrow. This will result in another
day of excessive heat, with highs very similar to what we are
experiencing this afternoon. Thus have extended the excessive
heat warning and heat advisory through Thursday evening. The one
thing of note for tomorrow is a couple of the convective allowing
models such as the HRRR show some isolated showers or storms
developing in the late afternoon and evening hours. Given the
strength of the upper ridge overhead confidence is low in this
scenario. Have kept mentionable PoPs out of this forecast package
but a slight chance of PoPs may need to be added in subsequent
forecasts. Coverage would likely remain low but any storm that
does develop would have the potential to produce strong downburst
winds. Otherwise, the very hot and dry conditions will persist.
&&
.LONG TERM...
(Thursday night through next Wednesday)
Issued at 310 PM CDT Wed Aug 21 2024
Gusty south winds will be possible Thursday night, mainly across our
central and northern counties. With development of a low-level jet,
one of the hi-res models indicate a potential for gusts over 25 mph
in the overnight hours. This setup could keep low temperatures above
80 degrees across some of the Big Country and Concho Valley, and
limit lows 77-79 degrees elsewhere.
The strong upper level high will shift northeast over the Red River
Valley on Friday. Highs on Friday won`t be quite as hot in our area,
but will still be in the Heat Advisory range (105-108 degrees) for
most if not all of the Big Country and Concho Valley. Our Heartland
and southern counties will have highs in the 100-103 range.
The upper high will continue shifting northeast across Oklahoma
Saturday, and into eastern Kansas and western Missouri Sunday. With
With an extension southwest across West Texas, this high is expected
to remain our dominant weather influence through the weekend. With
gradual weakening of the 850mb thermal ridge, at least temperatures
will not be as hot, but will remain above normal. Expect highs
Saturday and Sunday to range from 100-104 in most of the Big Country
and Concho Valley, to the mid and upper 90s in our southern
counties.
A forecast change in the upper level pattern next week is expected
to result in temperatures trending at least a little cooler in our
area, and some rain chances. An inverted trough is progged to move
from the northern Gulf of Mexico west into South Texas on Monday.
Medium range models differ on the subsequent track of the system
Tuesday and Wednesday, with potential for it to linger over south-
central Texas or move northwest up the Rio Grande Valley toward the
Big Bend area. This has implications on the potential extent of rain
chances and cloud cover for our area, and on the extent of the
cooling trend with temperatures. At this time, we have a low chance
(20 percent) for showers and thunderstorms in some of our southern
and southeastern counties Tuesday afternoon, and across much of the
southern half of our area Wednesday afternoon. At this point, we
have forecast highs Tuesday/Wednesday generally ranging from the mid
90s in our southern counties, to the upper 90s to 101 in the Concho
Valley and Big Country.
&&
.AVIATION...
(00Z TAFS)
Issued at 615 PM CDT Wed Aug 21 2024
VFR conditions are expected for the next 24 hours. We have a few
showers and thunderstorms around our area this evening, however
impacts are not expected at any of our TAF sites. Storms should
continue south and eventually weaken by sunset. Isolated storms
could develop tomorrow late afternoon as well, but confidence is
too low to include them in this TAF package.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 79 109 82 107 / 0 10 10 10
San Angelo 80 109 80 106 / 0 0 10 10
Junction 77 107 77 101 / 10 10 10 10
Brownwood 77 108 78 103 / 10 10 10 10
Sweetwater 80 111 82 108 / 0 0 0 10
Ozona 76 103 77 101 / 0 0 0 10
Brady 77 106 78 102 / 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 9 PM CDT Thursday for Brown-
Callahan-Coke-Coleman-Concho-Fisher-Haskell-Irion-Jones-
McCulloch-Nolan-Runnels-San Saba-Shackelford-Sterling-Taylor-
Throckmorton-Tom Green.
Heat Advisory until 9 PM CDT Thursday for Crockett-Kimble-Mason-
Menard-Schleicher-Sutton.
&&
$$
SHORT TERM...42
LONG TERM....19
AVIATION...AP
Area Forecast Discussion
National Weather Service Topeka KS
623 PM CDT Wed Aug 21 2024
.KEY MESSAGES...
- There are small chances for showers and thunderstorms early Thursday
and Friday mornings; otherwise mainly dry weather is expected
to hold through early next week.
- One more day of slightly below average temperatures Thursday before
a warm-up is forecast into the weekend.
&&
.DISCUSSION...
Issued at 244 PM CDT Wed Aug 21 2024
The forecast area remains under the influence of expansive sfc high
pressure centered over the Great Lakes and upper Mississippi River
valley. The upper levels consist of a ridge over TX/NM in between
troughing over New England and the British Columbia coast. As such,
southeasterly winds on the southwest periphery of the sfc high
continue to keep cooler and drier air in the area. Afternoon
temperatures are still expected to top out in the 80s with dew
points in the 60s.
Heading into tonight and Thursday, a weak perturbation on the
northern periphery of the upper ridge along with upslope flow should
help to develop convection off the High Plains. This is progged to
move eastward across KS through the overnight hours, but it will be
moving into a more stable environment as it does so. Additionally,
forecast soundings in north central KS don`t show a lot of moisture
through the column. Some CAM guidance does show rain making it into
western portions of the area during the predawn hours before
dissipating later in the morning, but am overall unimpressed with
the limited instability and moisture in place. As such, have held
onto PoPs in case there is enough ascent from isentropic lift and
any remnant MCV, but have limited them to 25% or less. Perhaps of
note is that the new 18Z HRRR has slowed down this activity compared
to 12Z model runs, so it`s possible the rain may just come later in
the morning than previously anticipated.
Once the morning wave moves off, another perturbation aloft is
progged to develop another round of scattered showers and storms
late Thursday, moving northeast into Friday morning. Again there
doesn`t appear to be as much instability this far east, though there
could still be enough isentropic lift to produce precipitation.
Still, rain chances are favored more north and west of the area with
the wave moving northeastward, so have limited PoPs to 20% or less
in the western counties between 06-12Z Friday.
Meanwhile, the upper trough near British Columbia will have been
amplifying and digging along the western US. This should help the
upper ridge to expand northward, increasing mid-level heights over
the area and bringing a thermal axis overhead into Saturday as well
as increasing low-level moisture. Saturday currently looks like the
hottest day of the upcoming week, with highs in the mid 90s to low
100s. Will continue to monitor trends for the next few days, but if
the current forecast holds, a Heat Advisory may be needed
particularly for southern portions of the area. Sunday is a little
less certain as heat indices around 105 look less widespread and
more brief, but it will still be hot with highs around 100.
By Monday, the main upper trough looks to deamplify and push a weak
cold front through the region into the evening. Deterministic models
are showing some precipitation associated with this, but the better
upper support may be well north of the area depending on how strong
the trough remains. At the very least, this should help to flatten
the upper ridge and bring temperatures down a bit into the next work
week. Highs are forecast in the 90s, which is still above average
but not as hot as this weekend. Rain chances look quite low given
the uncertainties in the troughing pattern.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 620 PM CDT Wed Aug 21 2024
VFR prevails tonight and Thursday. Winds turn more easterly
tonight and decrease below 10 kts. A slight increase is then
expected again after sunrise Thursday. A few showers may
approach KMHK Thursday morning, but chances remain low, around
15 percent.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Picha
AVIATION...Teefey