Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/11/20
Area Forecast Discussion
National Weather Service La Crosse WI
1049 PM CDT Mon Aug 10 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 213 PM CDT Mon Aug 10 2020
Latest 19z surface analysis shows cold front extending from southern
Ontario Canada into southern Iowa. Latest mosaic radar imagery
indicates mesoscale complex along surface front with showers north
of main complex of convection over southern forecast area.
Surface ridge over the Northern Plains states will build into the
Great Lakes Region tonight and Tuesday. This will provide dry
weather across the forecast area. Stronger winds aloft are expected
to inhibit any widespread fog development in the Mississippi River
and some of the tributaries.
Temperatures tonight will drop into the upper 40s to 50s and highs
are expected to climb into the upper 70s to middle 80s Tuesday.
.LONG TERM...(Tuesday night through Monday)
Issued at 213 PM CDT Mon Aug 10 2020
The 10.12z GFS/NAM/ECMWF are in good agreement in developing west to
east zonal flow aloft Wednesday into Thursday. The combination of
pieces of energy in the flow and southerly moisture return will
produce on and off small shower and storm chances across much of the
forecast area. Main focus of convection will be west of the forecast
area...where better vertical motion and moisture convergence is
located. High temperatures Wednesday into Thursday will be near
seasonal with highs mainly in the lower to middle 80s.
Main forecast concerns Friday through Monday are precipitation
chances through much of the period. The 10.12z GFS/ECMWF/GEM show
differences with overall flow pattern through the period. Main
differences is how amplified upper level ridge will be over the
eastern United States and the strength of the upper level trough
over the Northern Plains states. This will have impacts on timing
of the small convection chances Friday into Sunday across the
forecast area. Depending on timing...subsidence underneath
shortwave ridge will allow for dry weather Monday. Temperatures
Friday and Saturday will be the warmest out ahead of the upper
level trough...as the 10.12z GFS/ECMWF indicate 925mb warming to
plus 20 to plus 23 degrees celsius. High temperatures will be well
in the 80s. Cooler air advects into the forecast area behind upper
level trough Sunday and Monday with highs cooling into the 70s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1049 PM CDT Mon Aug 10 2020
Look for this to be a quiet period with VFR conditions. An area of
high pressure over southeast South Dakota late this evening will
drift slowly east and be over northern Illinois by Tuesday
evening. This will keep skies relatively cloud free with light
west to southwest winds. Not expecting any valley fog to form and
impact KLSE tonight as both the 11.00Z NAM and 11.02Z RAP shows
winds of 10+ knots from about 1000 feet and up for much of the
night that should create too much mixing just above the surface to
allow fog to form.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DTJ
LONG TERM...DTJ
AVIATION...04
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
848 PM EDT Mon Aug 10 2020
.UPDATE...
Quick update this evening for the timing of showers and storms.
Enough instability with ML CAPEs of 1500 to 2000 J/Kg with the MCV
moving through central Lower to have categorical POPs for the western
part of the CWA but with the weakening trend only have likely POPs
for the eastern part. Severe threat is waining also with little
shear and decreasing instability with the loss of diurnal heating.
&&
.PREV DISCUSSION...
Issued at 704 PM EDT Mon Aug 10 2020
AVIATION...
Potent squall line crossing Lake MI will impact the TAFs sites just
after 02z based on current forward speed and propagation. Hi-res
runs continue to suggest that the storms will be weakening quite a
bit as they get into southeast MI. While wind fields are much weaker
over the region, there is still enough instability with the
convective vort over Lake Michigan that the storms should hold
together but will likely be sub-severe. Hi-res runs also continue to
hold onto additional development with ahead of the cold front after
the evening convection...around 05z for MBS to as late at 11z for
the Detroit area.
In the wake of the convection, expect a period of MVFR cigs and
vsbys into Tuesday morning. Eventually, the cold front will pass
through the forecast area with much drier air for Tuesday late
morning and beyond.
For DTW...Specific timing for DTW would place the storms arrival
between 0210z to 0235z. While severe wind gust not likely, potential
for a 30 to 35 kt gust. Much greater uncertainty with the second
batch of thunderstorms after 06z.
DTW THRESHOLD PROBABILITIES...
* Medium for ceiling at or below 5000 ft from 02z through 15z.
* High for thunderstorms from 02z to 04z and medium from 06z to 12z.
PREV DISCUSSION...
Issued at 356 PM EDT Mon Aug 10 2020
DISCUSSION...
A warm and muggy day remains underway as temperatures sit firmly in
the upper 80s with dew points holding in the lower 70s with with
only a minimal cumulus response as seasonably warm h700 temperatures
hold between 9-10C. For the remainder of the afternoon... Increasing
build up of moisture ahead of an approaching cold front, still just
west of Lake Michigan, will gradually increase precipitation chances
across central Michigan this afternoon as near full solar insolation
has allowed for rapid destabilization of the atmosphere.
Aforementioned lower-level cap and lack of synoptic support will hold
precipitation chances at just a chance through the afternoon and
early evening, with any development mode being pulse in nature and
short-lived as deep layer bulk shear values remain weak, to or just
below 20 knots. Regardless, with MLCAPEs rising around 2,000 J/kg
across Flint into the Tri-Cities (1,500 J/kg for locations south)
this afternoon, any pre-frontal pulse thunderstorms will be capable
of producing heavy downpours and wet microbursts.
Attention then turns to an upstream MCS complex now just entering
northern Indiana which has had a history of producing damaging wind
gusts across Iowa. Latest 16Z HRRR (and support from 1000-500 MB
thickness) continues to advertise an ESE prorogation of the storm
system which has it clipping southwest Michigan by 00Z before taking
a more southeasterly trajectory following the better CAPE gradient
down into the Ohio Valley. However, have noted that the forward
propagation of the current system is faster than that displayed in
the HRRR model runs (no surprise given strong RIJ), which could clip
Michigan sooner than expected, capitalizing on better instability.
Integrity of the system could still hold and clip southern Michigan
given the sufficient mid-level lapse rates between 6-7C and
instability in place, but maximum bulk shear values will continue to
be a limiting factor. This ongoing system bears watching as we head
into the evening, mainly 23Z onwards, and would be primarily a wind
threat, where damaging winds will be possible. Additionally, strong
fgen along an advancing cold front/upper level shortwave will bring
additional chances for thunderstorm development for the remaining
areas of the cwa, with similar thermodynamic and kinematic variables
in place this evening. Slight uptick in bulk shear values to 25
knots ahead of the front (slight uptick in mid-level wind speeds)
and cooler mid-levels will help support more organized convection,
but timing of thunderstorm development (~00Z-05Z) will be met with
waning instability, and would promote a weakening trend from west to
east. Overall, all of SE MI remains in marginal/slight risk for
severe weather tonight per SPC mainly for wind gusts concerns, where
gusts around 60 mph will be possible with stronger storms. Otherwise,
heavy downpours leading to localized flooding concerns and lightning
will be the primary threats with thunderstorm development. Severe
weather threat will quickly wane after Midnight.
Post-frontal dry air will quickly fill in behind the cold front with
lingering rain showers early overnight. Residual moisture axis in
conjunction with diurnal heating could produce some weak showers
early Tuesday afternoon, but a building high pressure system will
fill in behind the front and will produce dry weather through at
least the midweek period. Zonal flow/little change to thermal
profile will support temperatures in the mid-80s through the week
with dew points in the upper-50s to lower 60s. Better chances for
rain and thunderstorm returns through the weekend as a warm front
edges north into the region.
MARINE...
Light southwesterly winds will continue to bring warm and humid
conditions into the central Great Lakes for the remainder of the
afternoon, while a cold front moves in later this evening bringing
the chance for showers and thunderstorms. Strong to severe
thunderstorms are possible with strong wind gusts, frequent
lightning, and erratic waves being the primary marine threats. Wind
gusts are expected to remain at or below around 20 knots with the
passage of the cold front, although higher gusts are possible with
thunderstorm activity. The passage of the front causes a shift to
northwesterly flow, also allowing showers and thunderstorms to
diminish during the early morning hours. High pressure then begins
to build overhead, with light winds and dry conditions persisting
through the middle of the week.
HYDROLOGY...
Warm and humid air is firmly in place over SE Mi today as a cold
front approaches from the Plains and Midwest. Clusters of
thunderstorms are expected to develop west during the afternoon and
move into the region with the front tonight. Rainfall totals average
a quarter to a half inch in this pattern with locally higher amounts
to or in excess of one inch will be possible with any thunderstorm
development. Heavy rain threat will end around or slightly after
Midnight.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......RBP
AVIATION.....RBP
DISCUSSION...SF
MARINE.......MV
HYDROLOGY....SF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Hanford CA
102 PM PDT Mon Aug 10 2020
.SYNOPSIS...Scattered afternoon thunderstorms over the Sierra
Nevada mainly north of Tulare County are possible through
Tuesday. Normal to above normal afternoon highs will continue
across the valley for the next week.
&&
.DISCUSSION...
Seasonably hot weather to continue across the San Joaquin Valley
today as many areas are forecast to surpass the century mark by
afternoon. High temperatures are forecast to be in the 98-103
degree range for most of the valley today. Latest GOES17 imagery
is depicting some building CU over the Sierra Nevada, mainly north
of Tulare County. HRRR model guidance is showing thunderstorms
developing around 2 PM; these thunderstorms will be capable of
gusty winds 40-50 mph, small hail, and localized downpours.
High temperatures will moderate a couple degrees tomorrow as
upper troughing begins to influence the area. Afternoon convection
over the Sierra Nevada again look possible, mainly north of
Tulare County as instability prevails. The trough will usher in
drier air aloft by Wednesday and this will likely halt the chance
for convection as dew points are forecast to be 10-12 degrees
lower than on Tuesday. High temperatures to remain near normal
through Wednesday and Thursday as the upper trough slowly advances
over the area. Some moisture from Tropical Storm Elida may pivot
around a desert southwest ridge by Thursday and Friday, which
could bring some cloud cover over Central California these days.
By this weekend, a strong upper ridge will shift west over Central
California, heralding the return of widespread triple digit heat.
Afternoon highs by Saturday will range from 100-105 degrees
across the SJ Valley, and up to 104-109 degrees in Indian Wells
Canyon.
&&
.AVIATION...
Isolated thunderstorms can be expected near the Sierra crest
through 03z Tuesday. Otherwise, VFR conditions will prevail over
the central California interior during the next 24 hours.
&&
.AIR QUALITY ISSUES...
On Monday August 10 2020... Unhealthy for sensitive groups in Kern
County and Sequoia National Park and Forest.
Further information is available at Valleyair.org
&&
.CERTAINTY...
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is high.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
an/or to provide feedback.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
public...Bollenbacher
aviation....Bollenbacher
weather.gov/hanford
Area Forecast Discussion
National Weather Service Lincoln IL
815 PM CDT Mon Aug 10 2020
.SYNOPSIS...
Issued at 253 PM CDT Mon Aug 10 2020
Scattered thunderstorms will affect the area into tonight. Some of
the storms could be severe into this evening, with damaging wind
gusts being the main threat. Locally heavy rain will also be
possible. The front will push into southern Illinois for Tuesday
and Wednesday, with scattered storms more dominant over the
southern half of the state. Temperatures will cool a bit for the
next few days, with more seasonable readings through midweek.
&&
.UPDATE...
Issued at 815 PM CDT Mon Aug 10 2020
Main gust front has pushed south of our forecast area limiting
potential for severe winds. Plan on hanging on to SVR 428 a bit
longer south of I-70 given proximity of the extrmely unstable air
to our south and the nearby warnings being issued by WFO PAH.
Otherwise, 3km NAM and lates HRRR CAMs are trying to keep chances
for thunderstorms in place over central and southeast Ilinois
into the early morning hours. This seems reasonable given the
depiction of the triggering shortwave still lingering over central
Iowa nd Southwest MO. Will make some adjustments to lower PoPs in
the northwest but will retain at least chance in the central and
southeast through the night.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 253 PM CDT Mon Aug 10 2020
Greatest severe weather threat at least over the next couple of
hours will be across the northern CWA, mainly I-74 north as the
squall line tracks east. Widespread 60+ mph gusts with tree and
power line damage have been reported across Knox and Stark
counties as of 230 pm. This area will shift east over McLean Co.
through 4 pm. Progressing south of I-74 this line of storms
becomes more outflow dominant, posing a lower severe threat over
the short term. Upstream we are seeing another batch of severe
storms developing over northeast MO. CAMs have had varying
solutions with this activity, but the general feeling is this will
develop east along the front/outflow from initial squall line, and
pose an additional severe threat over the central/southern CWA
later this afternoon and into the evening. Though deep layer shear
remains rather weak under 25 kt, very high instability (surface
based sampled at 5400 J/kg on 18z ILX sounding) will lead to a
continued damaging wind gust potential into this evening. Steep
mid level lapse rates will also pose a secondary hail threat,
mitigated by high wet bulb zero heights. We expect the main severe
threat to diminish over out southeast counties around 9-10 pm.
A lesser but still notable concern over the next few hours is high
heat and humidity as 80F dewpoints have pooled ahead of the storm
complex. This has pushed heat indices around 105F in many
locations. This will continue through around 6 pm in areas that
remain storm-free.
Later tonight and Tuesday, the front will shift into southern IL.
This is where chance pops will be confined, with drier weather
expected over the northern half of the CWA into Tuesday night.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 253 PM CDT Mon Aug 10 2020
Few changes made to the extended due to ongoing severe weather.
The front will remain in the general area Wed-Sat, though notable
dry periods are likely, especially over the northern half of the
area. This will keep seasonably warm weather in place through
Saturday. While there is some uncertainty in timing an more
significant cold front is progged late Saturday or early Sunday.
This would result in cooler/drier weather for the end of the
weekend and into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 605 PM CDT Mon Aug 10 2020
Rain with isolated embedded thunderstorms will persist for the
next couple hours, diminishing from the west. A brief reduction to
MVFR ceiling/vis possible in a heavier shower/storm, but chances
are too low to include in the TAFs. After the rain exits this
evening VFR skies with mid to high level clouds into Tuesday
afternoon. Any lingering gusty winds in showers will diminish over
the next couple hours, then winds will remain under 10 kt through
tomorrow afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barker
SYNOPSIS...25
SHORT TERM...25
LONG TERM...25
AVIATION...25
Area Forecast Discussion
National Weather Service Marquette MI
741 PM EDT Mon Aug 10 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 432 PM EDT MON AUG 10 2020
Water vapor imagery and RAP analysis show a mid-level low over
northern Manitoba with broad trof extending s into the Northern
Plains/Upper Mississippi Valley. Fairly well-defined shortwave that
has lifted from the eastern Dakotas to just n of Lake Superior has
provided some assistance to convection that has been developing
along and ahead of sfc cold front which currently runs from eastern
Lake Superior across central Upper MI. Per SPC mesoanalysis, air
mass ahead of the front is characterized by MLCAPE upwards of 2000-
2500j/kg with deep layer shear of 30-35kt. Thus, storms have been
well-organized at times, posing a svr risk. Behind the cold front,
dwpts are falling off quickly from the excessive values ahead of the
front in the upper 60s/lwr 70s F. KIWD and KLNL are already down to
around 50F. Farther w, dwpts this aftn across the Dakotas are well
down into the 30s and lower 40s F, a sign of the drying that will
continue into Tue.
Ongoing convection (and its associated svr risk) ahead of cold front
will continue to push s and e over the next few hrs, clearing the
fcst area by 00z. Much drier air as already alluded to above will
stream into the area during the night, resulting in skies becoming
clear. Given the dry column, leaned fcst toward some of the cooler
guidance for min temps. 50s will generally be the rule, but around
60F near Lake Superior and probably dipping into the upper 40s in
the typically cooler areas in the interior.
Expect abundant sunshine on Tue under a dry air mass. Given the low
dwpts present upstream across the Dakotas and into western MN,
incorporated some of the mix down potential to lower dwpts beyond
all guidance. Although dwpts will be comfortably low, down into the
40s F for most of the fcst area, it will be a warm day as midday
850mb temps will be around 14/15C. Highs should generally be in the
mid 80s with some upper 80s where w to wsw winds are a downsloping
wind direction. Will be a little cooler where those winds are
onshore from the Great Lakes. Deep mixing in the dry air mass will
support breezy conditions. Fcst soundings suggest gusts of 20-30mph
during the day, strongest over the nw half of the fcst area.
Although it will be warm and breezy with RH down as low around 25pct
in the aftn, recent rainfall will ease fire wx concerns.
.LONG TERM...(Tuesday night through Monday)
Issued at 335 PM EDT MON AUG 10 2020
Not much has changed for the forecast through the extended. It will
remain on the warm side throughout the week with temperature
remaining around 10 degrees above normal for this time of year.
While the warmth will persist, the humidity levels will drop
significantly through at least Wednesday as an anomalously dry
airmass moves into the region.
The weather looks to remain dry and warm through mid-week as high
pressure lifts northeast across the area and up into Canada by late
week. Medium range guidance diverges quite a bit through the end of
the week when it comes to thunderstorm chances. This is not a
surprise given the strong surface ridging moving through the region
and a blocking high/ridge over the Southwest slowing the progressive
nature of the upper-air pattern across the CONUS. Thus, not going be
confident on precipitation chances until late week/weekend. However,
once we get to the end of the week and through the upcoming weekend,
the weather should become more active as longwave troughing tracks
east across the Upper Great Lakes and a few embedded shortwaves
rotate through the area. By early next week it does look like we
will see a cool down, back towards near-normal temperatures as the
above mentioned longwave trough digs southeast of the area and
northwest flow prevails.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 739 PM EDT MON AUG 10 2020
Clear skies and drier air over the region will keep VFR conditions
at all three TAF sites this forecast. Main concern is gusty winds
developing tomorrow with daytime mixing, with gusts to around 20
knots until late afternoon expected at all three sites.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 432 PM EDT MON AUG 10 2020
In the wake of a cold front clearing Lake Superior late this aftn,
wsw winds will gust up to 20-25kt across the west half of Lake
Superior tonight. Winds will be slightly lighter over the east half.
Winds will increase some on Tue under tightening pres gradient btwn
low pres over Hudson Bay and high pres shifting e toward the
southern Great Lakes. Expect gusts into the 20-30kt range across the
w half of Lake Superior on Tue, strongest off the w side of the
Keweenaw Peninsula. Wind gusts should be mainly under 20kt over much
of the e half. High pres ridging will then dominate thru the midweek
period, keeping winds under 20kt. Winds should increase a bit during
the late week period as the high pres ridge shifts east. Gusts may
reach 25kt at times over mainly the e half of Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...RJT
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
338 PM CDT Mon Aug 10 2020
.UPDATE...
Issued at 338 PM CDT Mon Aug 10 2020
Update to the aviation section. Going to discuss the overall
faster trends in the models. The latest HRRR seems more in line
with reality. If it pans out, we could see activity into our SEMO,
southwest IL counties by 6 or 7 p.m., and then along a line from
Evansville to near Paducah by 10 or 11 p.m.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 234 PM CDT Mon Aug 10 2020
Easily verified the Heat Advisory across most of the area with
around 105F values, actually 105-110F over southern IL. We will
continue with the headline for heat through 7 p.m. Isolated
convection formed over the KY Pennyrile along a boundary. The rest
of the area is quiet for now.
Attention is on severe convection over NW IL back into northern and
west MO. This activity is running faster than most all of the CAMs
guidance. It`s also more prominent over Missouri (CAMs lacking). The
convection is focused along a boundary and driven by a mid level
wave. We project the activity will get into our area late today, or
this evening. Timing is still a bit of a tough call. But as of right
now if trends continue, the CAM`s and deterministic solutions are
likely too slow. Expect additional adjustments to timing between
now and midnight. Severe is certainly a concern given the high
degree of instability, favorable mid level drier air, decent lapse
rates and overall momentum. Highest chance area is from parts of
southeast MO into southern IL and southwest IN. Chances lower
overnight with any southward progress.
What will determine Tuesday`s PoPs are how prominent and expansive
the convection is tonight. The airmass could get worked over. Or if
the activity weakens enough, and sets up a zone of instability and
convergence over southern sections, we could see renewed convection.
We lowered Pops overall given the possibility of the former
happening. There will be another chance of showers and thunderstorms
Tuesday night. We will take another look as highs on Tuesday. We may
be a bit too warm with the current forecast.
.LONG TERM...(Wednesday through Monday)
Issued at 234 PM CDT Mon Aug 10 2020
Plenty of moisture will remain across the middle Mississippi and
lower Ohio valleys the rest of the week. Models show an upper level
trof over our region through the week. At the surface, a cold front
will meander across our region through Friday. This will continue to
give us chances of showers and thunderstorms Wednesday through
Friday, with the best chances during the late morning and afternoon
hours.
Models lift the front north of our area by Saturday, and push the
upper trof just east of our region. However, with moisture still in
place, weak impulses in the mid/upper level northwest flow will keep
chances for isolated to scattered convection in the forecast through
the weekend. Best chances will continue to be diurnally driven,
with lower chances during the overnight. This pattern will continue
into Monday, though we could see temperatures and dew points finally
trending down a little.
High temperatures will generally be in the 86 to 91 degree range
Wednesday through Friday, then a couple of degrees warmer over the
weekend. Monday might only be in the lower to middle 80s. Lows
through the extended will be in the upper 60s to lower 70s. Daytime
dew points will be in the lower to middle 70s, dropping a few
degrees for the overnight hours.
&&
.AVIATION...
Issued at 338 PM CDT Mon Aug 10 2020
Strong to severe convection from central IL into central MO is
moving to the east, southeast faster than previously forecast,
and has expanded in coverage. We now project that by 03-05z, the
leading edge of the storms should be from about KEVV to KPAH.
Strong and gusty winds may accompany this complex of storms, along
with MVFR/IFR conditions in very heavy rain. It appears the
activity will let up after midnight, with variable light winds
developing and a return to VFR conditions, that should last
through Tuesday morning.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory until 7 PM CDT this evening for ILZ075>078-080>094.
MO...Heat Advisory until 7 PM CDT this evening for MOZ076-086-087-100-
107>112-114.
IN...Heat Advisory until 7 PM CDT this evening for INZ081-082-085>088.
KY...Heat Advisory until 7 PM CDT this evening for KYZ001>022.
&&
$$
UPDATE...08
SHORT TERM...08
LONG TERM...RST
AVIATION...08
Area Forecast Discussion
National Weather Service Pocatello ID
202 PM MDT Mon Aug 10 2020
.SHORT TERM...Tonight through Wednesday night.
General trend is for dry weather and breezy afternoon conditions
through the short term period. Fire weather products have been
issued to address this. Isolated thunderstorms are possible
Tuesday and Wednesday mainly in the southern highlands and eastern
highlands. Above normal daytime temperatures will continue through
Wednesday but will be a bit cooler on Wednesday. Expecting low
elevations highs in the low 90s Tuesday and upper 80s Wednesday.
Wind gusts in the Snake Plain generally in the 20 to 30 mph range
Tuesday and Wednesday extending north into the highlands as well.
GK
.LONG TERM...Thursday through Monday.
Expecting dry and hot conditions in the long term period as an
upper ridge builds overhead by next weekend. Temperatures will be
slightly above normal Thursday through Saturday with highs
expected to reach the mid to upper 90s by Sunday in low
elevations. May still be breezy Thursday and Friday but winds
should decrease through the weekend as the upper ridge builds
overhead.
GK
&&
.AVIATION...
Gorgeous wx for aviation will continue for yet another day across SE
Idaho, with mostly clear/VFR skies and no LLWS concerns. Breezy
afternoon winds have been the main (and really only) element of any
consequence, and speeds look slightly weaker today across MOS/HRRR
guidance compared to what we saw over the weekend, with trajectories
lining up well with most of the major runways. Overall forecast
confidence is high. KSUN may yet again see a shift from SE to SW
this afternoon, and while the signal is weaker compared to the
weekend, we have included it in the TAF. Timing should run a bit
behind yesterday...perhaps 21z (3 PM), producing a slight crosswind
at the terminal. Winds veer further into the west just off the sfc.
Several of the HREF ensemble members, with support from the latest
HRRR/RAP, do hint at an isolated t-storm developing near the ID/UT
border south of KBYI, and in the Central Mntns near Challis/Mackay
NE into srn MT after 21-22z (3-4 PM), and while this should not
impact our TAF terminals, did throw a few clouds into KSUN to
account for some nearby cumulus development in the terrain. We also
continue to monitor smoke production from the Phillips Creek Fire
for possible advection east toward KSUN, but sfc obs, webcams, and
DEQ air quality stations continue to suggest this has not been a
major problem, and the HRRR smoke model doesn`t throw any red flags
for today, so suspect KSUN will remain unaffected. Looking to Tue, a
trough is forecast to push inland across the PacNW, increasing our
SW flow (esp for the Snake Plain terminals) and potentially working
a few t-storms into the srn highlands. Early projections suggest
this activity should stay south of KBYI and KPIH, but it may be
close. Breeziest conditions should affect KPIH and KIDA. - KSmith
&&
.FIRE WEATHER...
Dry wx continues with no significant relief in sight. After
extensive coordination with SPC, GBCC, fire dispatch centers, and
surrounding offices, we have upgraded the FIRE WEATHER WATCH to a
RED FLAG WARNING from 1-9 PM Tues for Zones 476 (ern Central Mntns),
425 (ern Magic Valley), and 410 (Snake Plain). RHs are a slam dunk,
with winds the weak link, barely brushing low-end criteria for most
areas with low confidence even after blending in an 80-90% composite
of the normally breezier/more accurate MAV/MET guidance for the
Snake Plain. A key decision here was: Is the case stronger for
upgrading to a warning, or canceling the watch and having no alerts
out due to the marginal winds? Given a forecast Haines Index of 6,
RH values as low as 8-11%, and winds just a few kts short, we felt
an upgrade was more appropriate. We also wanted to make a decision
today to give fire partners some lead-time on the warning, instead
of waiting until full coordination would be possible again late Tue
AM. There is still the potential for an isolated t-storm to sneak NE
from NV into Zone 427 (Cassia County) or even wrn 413 Tue eve, but a
review of our first full round of high-res reflectivity guidance
suggests any activity will likely remain isolated, with better
potential south of the border. CWR is near zero given the dry low-
level airmass. Winds/RH are also too marginal for 427 to include
them in the Red Flag. Wed we flip-flop...widespread critical winds
appear likely across every zone (except perhaps 427), but RHs are in
question (should increase with some moisture working up from the
south). Best overlap of critical winds/RH exists over wrn 410, so we
issued a FIRE WEATHER WATCH here from 1-9 PM Wed. If RHs were to
trend lower, additional zones may need to be considered. Overnight
RH recovery is mediocre at upper slopes Tue night (struggling to
reach 40%) as also noted by crews on fires in BOI`s area, but all-in-
all didn`t see a strong meteorological reason to run a Red Flag
right through the entire 2 days as our neighboring MSO/TFX offices
are doing in MT. Finally, t-storms remain possible Wed afternoon/eve
across the ern/srn highlands, but a first look at the NAMNest
suggests isolated coverage, so confidence is very much not there for
triggering a Red Flag based on lightning at this time. The PacNW
trough will stay with us Thurs with a chance of critical winds/RH
overlapping at least for Zones 410/476, but with headlines already
out for 2 days, did not want to issue for Thurs and potentially
cause confusion. A weak cold front may cross the region Thurs eve.
This weekend appears to feature a building ridge of high pressure
with hotter temps. - KSmith
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM to 9 PM MDT Tuesday for IDZ410-425-
476.
Fire Weather Watch from Wednesday afternoon through Wednesday
evening for IDZ410.
&&
$$
Area Forecast Discussion
National Weather Service Riverton WY
435 PM MDT Mon Aug 10 2020
.SHORT TERM...(This evening through Tuesday night)
Issued at 130 PM MDT Mon Aug 10 2020
Totally clear skies early this morning have given way to building
cumulus early this afternoon, particularly on the north side of
the Uintas and northward toward Big Piney and Pinedale. Expecting
more cumulus to build over the Wind Rivers and Absarokas and move
eastward during the late afternoon and early evening. Continues to
be very isolated chances of thunderstorms over these areas for
the rest of the day, and the HRRR is also indicating the Wind
River Basin into Natrona County early this evening due to slightly
higher surface moisture and weak low-level shear. Thus, the
storms should not be very strong and the bigger hazard would be
from dry lightning. Breezy and dry conditions continue across
southern WY for elevated fire weather conditions this afternoon
and early evening as well. Skies will be mostly clear overnight
with some clouds across the northern mountains and possibly
southern WY.
Tuesday will see more clear skies across much of northern WY as
dry windy conditions move in from eastern Idaho. Some mid-level
moisture will slowly stream from northern Utah across southern WY
as the mid-level flow becomes more west-southwest. As a weak
leeside surface trough develops over eastern WY, winds will
increase Tuesday afternoon with 700mb flow increasing to 20-30
knots and the height gradient tightening. Have continued the
forecast with a slight chance of showers and thunderstorms from
southwest WY ENE toward Natrona County and across Sweetwater
County. Dry lightning will certainly be a concern Tuesday
afternoon. Thus, a red flag warning is in effect from much of the
forecast area for lower afternoon humidities and stronger winds. A
weak shortwave trough from Nevada will move northeastward Tuesday
night into Wednesday morning toward western WY. The western areas
will see clouds increase early Wednesday morning with a slight
chance of showers around sunrise over the far western mountains.
Afternoon temperatures continue to be near of just above normal
for early August, with the drier overnight air
.LONG TERM...(Wednesday through Monday)
Issued at 150 PM MDT Mon Aug 10 2020
Not much change over the past 24 hours in the expected evolution of
the overall synoptic pattern. Shortwave and mid-level moisture will
progress across western Wyoming Wednesday in southwest flow aloft
ahead of broad trough over western Canada. Wednesday afternoon and
evening will likely provide the best chance for showers and
thunderstorms during the medium-range period. The broad Canadian
trough tracks across the northern Rockies Thursday and Friday.
Northern stream jet axis will remain to our north both days. This
will largely keep any chance of convection limited to locations near
the Montana border. However, there is a southern stream jet of 70+
knots that will cross the south Thursday. This will only add to the
fire weather concern for Thursday. While the jet energy will subside
across the south Friday, wind speeds will still pose a problem as
the trough swings to our north. Fire weather highlights are quite
possible both days, the question will be the areal extent. Blended
models have increased wind speeds for Thursday and Friday to come
more in line with what is most probable, so only made minor
adjustments. Speeds of 20 to 30 mph still appear to be on-track for
many areas. A cold front is still expected to slip into the north
Friday afternoon, which will limit fire weather concerns over the
Bighorn Basin and Johnson County.
The weekend and Monday will be trending warmer with less wind in the
forecast. The northern Rockies trough and associated jet will lift
into central Canada Saturday. This leaves Wyoming in general
westerly flow aloft with a relaxed pressure gradient. Therefore,
fire concerns will diminish for the weekend. A ridge over the Desert
Southwest and Great Basin then takes hold effectively shutting off
any potential for moisture to make its way north. 598dm high will
also crank up the heat with 700 temperatures of 16-20C by Monday.
Ridge axis will remain to our west or along our western border.
Models do hint at some very low pops in the northwest Monday
afternoon, but moisture looks very limited.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday)
Issued at 430 PM MDT Mon Aug 10 2020
Isolated convection will dissipate with the setting sun around 02Z-
03Z/Tuesday. Gusty westerly wind across southwest Wyoming will
decrease to less than 10kts just prior to sunset. Terminals will be
VFR through 00Z/Wednesday. Gusty westerly wind anticipated to
develop at most terminals between 18Z-20Z/Tuesday Speeds of 15-25kts
will be common.
&&
.FIRE WEATHER...
Issued AT 150 PM MDT Mon Aug 10 2020
Elevated fire weather conditions continue this afternoon and early
evening across southwest into south-central WY due to very warm,
dry, and breezy conditions. Isolated thunderstorms are possible
over Sweetwater County this afternoon, and then from eastern
Fremont into Natrona early this evening. With the very dry
boundary layer, there is a chance again of dry lightning out of
any storms. Skies will clear overnight and winds should decrease.
Skies will be mostly clear to partly cloudy Tuesday, with wind
increasing after noon and becoming stronger than Monday. More
isolated thunderstorms are possible from Uinta/southern Lincoln
counties eastward toward the central mountain areas. Very dry air
and stronger wind will move over the western mountains as well. A
red flag warning is in effect from noon to 8 pm Tuesday for the
critical fire weather conditions. Wednesday will see a disturbance
move into western WY early in the morning and bring some weak
showers and possible dry lightning to northwest WY.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Tuesday for WYZ277>281-
283-285-287>289-300-414>416.
Red Flag Warning from 2 PM to 8 PM MDT Tuesday for WYZ276-282.
&&
$$
SHORT TERM...McDonald
LONG TERM...Jones
AVIATION...Jones
FIRE WEATHER...McDonald
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Charleston WV
936 PM EDT Mon Aug 10 2020
.SYNOPSIS...
Weather disturbances bring a chance of storms to portions of
the area tonight and Tuesday. Cold front arrives Tuesday night,
becoming stationary to provide shower/thunderstorm through the
end of the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 925 PM Monday...
Meso-alpha-scale convective system currently moving across
western Ohio is showing signs of gradual weakening. 00z analysis
indicates a significantly drier atmospheric profile across the
RLX CWA than what exists across western Ohio, along with an
increasingly stable airmass. Thus, the ongoing convection should
continue to weaken through the late evening hours as it begins
to encounter unfavorable sustainability factors. However, the
far western CWA may have just enough moisture depth and
instability to allow for a brief strong storm to occur with the
approaching line. As such, SPC has outlined portions of SE OH
and far NE KY under a Marginal Risk of severe weather for the
overnight hours. But again, this should not be a significant
severe weather event for our area.
Owing to the placement of the convection as of 01z, I have re-
drawn the POPs for tonight to account for a possible scraping of
the western and southwestern CWA from the line of
storms...especially as the steering flow aloft begins to shift
the overall system more towards the southeast. Elsewhere, a
rogue isolated shower/storm could develop overnight as various
ripples in the H5 flow advect across. Slightly greater
convective chances will exist during the day Tuesday as stronger
H5 s/w disturbances advect east, but have capped POPs at 30%
for Tuesday...mainly due to a rather warm thermal profile and
still some questionable moisture depth values.
As of 451 PM Monday...
Made some significant changes part of the Near Term forecast
period. Reduced POPs significantly for the remainder of this
afternoon and into the evening hours. A very dry atmospheric
profile exists across all but the far western CWA this
afternoon. Thus, any convection that tries to develop through
sunset should be very isolated, and mainly across NE KY (and
possibly far SW VA).
Focus for later tonight then turns to ongoing large bow echo
currently moving east across Illinois. This complex is prog to
move into Indiana over the next hour and begin to shift move
southeasterly. During the evening, this complex should
gradually weaken as it begins to encounter a drier and
increasingly stable airmass. At this time, severe weather is not
expected across our CWA tonight, and the majority of the
expected remnant convection is likely to be confined to the far
western CWA. As such, I have lowered inherited POPs for tonight
and Tuesday morning across the board by about 20%. Will likely
make further significant changes to POPs for tonight with
the evening update...once better convective trends and 00z
surface and upper air analysis takes place.
As of 215 PM Monday...
The surface high pressure, responsible for dry weather during the
last couple of days, will weaken even further by Tuesday. This will
allow for upper level disturbances to initiate convection from
abundant low level moisture in the boundary layer. Models show
differences in their solutions especially tonight. The RUC and NAM
suggest a possible MCV dropping from the northwest overnight
tonight. In other hand NMB and GFS/ECMWF models brings a dry quiet
night. Decided to introduce some PoPs across the area to account for
this possibility. Any precipitation activity should wane down before
sunrise Tuesday morning, but showers and storms are expected during
the afternoon and evening hours as additional upper shortwaves cross
the area.
Temperatures will remain above average through the period.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 209 PM Monday...
Surface high pressure will build into the Great Lakes Tuesday night
into Wednesday, bringing drier air across much of the northern Ohio
Valley, particularly areas north of Interstate-70 where dewpoints
mainly in the 50s to near 60 will exist. However, our area will
remain too far south of this feature to benefit from this drier air
as dewpoints are expected to be in the upper 60s to low 70s across
the region. In addition, a stalled frontal boundary across our area
will combine with shortwave energy aloft to produce a risk of
scattered showers and storms Wednesday afternoon and evening. The
frontal boundary will then remained stalled across the middle Ohio
Valley into Thursday, with additional chances for scattered showers
and storms continuing across the region.
With models showing PWAT values as high as 2 inches Wednesday and
Thursday, locally heavy rainfall is possible with any of the
convection that develops. While dry antecedent conditions will limit
a threat for widespread flooding concerns, can`t completely rule out
localized high water issues as these storms will be very slow
moving. Otherwise, weak shear and poor mid level lapse rates should
generally keep severe weather threat on the lower side through mid
week. In addition, high temperatures for Wednesday and Thursday will
be in the upper 80s to low 90s across the lowlands and 70s for the
higher elevations.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 209 PM Monday...
The aforementioned frontal boundary will continue to linger in the
vicinity of the middle Ohio Valley late week and to start the
weekend. This feature will continue to support daily chances for
showers and storms Friday and Saturday amid the warm and humid
airmass and mid level impulses aloft. By Sunday an upper level
trough is expected to drop into the Great Lakes region, which
should help the frontal boundary finally lift out of the area.
By early next week, models show a strong upper ridge amplifying
across the western US and broad troughing across the Great Lakes
and Ohio Valley. This should result in slightly cooler air with
temperatures slowly trending towards more normal values by the
end of the long term period. This feature should also help
maintain some chances of showers and storms across the region
with conditions remaining unsettled at times through early next
week.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 714 PM Monday...
VFR expected for much of the TAF period, although some areas of
river valley fog overnight may lead to IFR conditions.
Dissipating Cu field is ongoing as of writing with some patches
of mid/upper level cloudiness drifting across at times. Well to
the northwest, a severe line of convection across Indiana is
prog to move southeast across Ohio this evening, and eventually
shift more southerly. Most of our region should remain just to
the east of any of the more substantial convection (which should
weaken throughout the evening). KHTS may be just close enough
to require a period of VCSH (TS possible) later this
evening/overnight. Elsewhere, convective blow off should negate
greater fog development. Exception may be KEKN where fog may
develop before thicker cloud cover spreads across.
VFR expected to prevail Tuesday with a Cu field developing
during the day. Iso to widely sct convection may try to develop
across the region, but coverage is currently expected to be too
sparse to include in TAFs this far out in time.
Weak/vrb sfc winds this evening eventually becoming more SWrly
around 5 kts.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: Slight chance convective complex currently
over Indiana tracks a little farther east tonight, which would
bring greater precip chances to the area.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 08/11/20
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H H H H H H H H H L
HTS CONSISTENCY H H H H H H H H M L L H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H L L L M M M
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 00Z WEDNESDAY...
No widespread IFR conditions expected at this time.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...ARJ/RG
NEAR TERM...RH/ARJ
SHORT TERM...RG
LONG TERM...RG
AVIATION...RH
Area Forecast Discussion
National Weather Service Tulsa OK
925 PM CDT Mon Aug 10 2020
...UPDATE...
.DISCUSSION...
Convection across northeast OK and parts of west central AR
continues to slowly weaken, although keeping an eye on the
ongoing strong storms over western OK. CAMs output continues
to struggle with the evolution overnight, with the recent
HRRR suggesting that storms will slowly move into the region
later tonight continue to fester across eastern OK Tuesday
morning.
Main update to overnight forecast is to extend PoPs a bit
farther south after midnight.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 76 94 74 95 / 30 30 20 20
FSM 75 94 73 96 / 20 40 20 20
MLC 77 94 74 95 / 10 30 10 10
BVO 74 92 72 93 / 40 30 20 20
FYV 72 89 70 92 / 20 40 20 30
BYV 71 92 70 93 / 30 50 30 40
MKO 75 92 73 93 / 20 30 20 20
MIO 73 92 71 93 / 40 30 20 30
F10 76 92 73 94 / 20 30 10 10
HHW 77 97 75 97 / 10 20 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18