Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/03/22
Area Forecast Discussion
National Weather Service Bismarck ND
935 PM CDT Tue Aug 2 2022
.UPDATE...
Issued at 922 PM CDT Tue Aug 2 2022
Light precipitation and clouds are a little slow to clear out this
evening. Extended sprinkles/light showers in the southern JRV a
couple hours and slowed the clearing of the mid/high clouds
through the early morning hours. Otherwise no significant changes
to the going forecast. There is an area of convection over
southeast Saskatchewan that if it held together could clip the
Turtle Mountains after midnight but at this time think the
probability is too low to add any pops. Forecast RAP sounding
at Rolla continues to dry through the late evening and early
overnight hours.
UPDATE Issued at 612 PM CDT Tue Aug 2 2022
A cold front continues to push southeast through the forecast area
early this evening. Gusty winds northwest and north central should
diminish early this evening. The southwest and south central may
see a brief period of gusty winds behind the cold front also early
this evening. Sprinkles, isolate showers have pushed through all
but the far south central and southeast portion of the state and
will continue to exit the area this evening. Mid and high clouds
will be slower to exit the area but should eventually clear out
late tonight. Made some minor adjustments to pops and sky cover
based on latest satellite and radar imagery. Updated text products
will be transmitted shortly.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 332 PM CDT Tue Aug 2 2022
A chance for showers and a few thunderstorms tonight, followed by a
brief cooldown on Wednesday, highlights the short term period.
This afternoon, flow aloft was mainly zonal in the base of a very
broad longwave trough, with a more compact low to our north in
central Saskatchewan. At the surface, a deepening surface low was
centered in western Manitoba, with a trailing cold front
extending southwest across the forecast area. Scattered radar
returns have continued through the morning and early afternoon
ahead of the front, in a line from Carrington to Bowman, although
cloud bases of 8- 10k feet is keeping most rain from making it to
the surface. We did recently observe rain here at the office on
the southeast side of Bismarck, with gusty winds accompanying the
light rain.
While these light rain showers continue moving east, there is a
slight chance of isolated strong to severe thunderstorms this
afternoon and evening in our far north central as the cold front
moves through. Uncertainty remains on if convective inhibition will
erode for this, though, with high-res guidance trending toward
convection beginning to the east of the forecast area. We will
continue to advertise this chance, as the environment features
strong bulk shear on the order of 50 knots and instability around
2000 J/kg, which is very favorable for storms to become severe if
any were to develop.
Cloud cover and smoke aloft have kept temperatures in check so far
today for much of the south, although 1900 UTC temperatures have
reached the 90s in the far southeast and parts of the west where
skies have cleared more. We continue to monitor near critical fire
weather conditions, with relative humidity values dropping into the
low to mid 20 percent range, but winds haven`t been quite as breezy
ahead of the front as expected. Will keep near critical fire weather
wording, but expecting that will be all that is needed.
Chances for showers south and thunderstorms north central will
diminish through the evening, with skies clearing from northwest to
southeast and overnight lows in the mid 50s to mid 60s.
Wednesday will be a pleasant early August day in the post frontal
regime and under northwest flow aloft, with highs ranging from the
mid 70s north central to the upper 80s southwest. Heat returns to
the southwest due to a low level thermal ridge beginning to edge
into western North Dakota that will warm temperatures up even
further on Thursday.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 332 PM CDT Tue Aug 2 2022
The extended forecast is highlighted by hot temperatures Thursday
and Friday before temperatures become closer to normal and there
are on and off chances for showers and thunderstorms.
Considering the entire forecast area, Thursday is expected to be the
hottest day of the extended period. Flow aloft will be mostly zonal
on top of a broad high pressure extending across the Four Corners
region into the Southern Plains, with a strong low level thermal
ridge extending into the Northern Rockies and western Dakotas. 850mb
temperatures are forecast to be in the 28-31 C range across
southwest North Dakota, translating to surface temperatures around
100 F. Dew points only in the upper 40s to mid 50s should keep
apparent temperatures in this area from reaching over 100 F,
however.
There is more uncertainty on how hot temperatures will get on
Friday, as guidance continues to advertise a cold front sweeping
through the forecast area at some point on Friday. The deterministic
NBM forecast currently has highs ranging from around 80 in the far
northwest to the mid 90s in the far south central and southeast, but
a ~10 degree spread in the 25th/75th temperature percentiles shows
that there is still uncertainty on the timing of this front, which
will influence how hot temperatures get on Friday. Smoke aloft from
western US wildfires could also limit temperatures on both Thursday
and Friday, so that is something we will have to keep an eye on as
the week progresses.
Looking ahead to the weekend and into early next week, significant
differences emerge among ensemble guidance in regards to the
synoptic pattern. GEFS members favor weak ridging building back in
over the central CONUS while EC and Canadian members favor
primarily zonal flow with a shortwave trough approaching towards
the end of the weekend. There is general agreement on a warming
trend Saturday through Monday, with low chance PoPs each day, but
overall there is low confidence in how things will evolve.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 922 PM CDT Tue Aug 2 2022
VFR conditions are expected through the forecast period most areas.
The one exception may be the north where wrap around moisture
behind an exiting cold front will linger Wednesday morning,
providing the potential for a short period of MVFR ceilings. Most
likely TAF affected will be KMOT at this time so added a scattered
layer 14-18 UTC for now. Otherwise expect mid and high clouds
this evening, slowly clearing from north to south through early
Wednesday morning. Generally a northwest to north flow is expected
through the forecast period, winds will be a little gusty early
this evening.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...Jones
LONG TERM...Jones
AVIATION...TWH
Area Forecast Discussion
National Weather Service Boise ID
851 PM MDT Tue Aug 2 2022
.DISCUSSION...Showers and thunderstorms moved through the
forecast area this afternoon and evening, with the strongest
storms noted south of the Snake Plain. Showers have tapered off
through the evening, though a few showers continue across western
Harney county, and along the Nevada border. Warmer temperatures
expected tomorrow, with another push of afternoon showers and
thunderstorms. No changes planned to immediate term forecast.
&&
.AVIATION...Mainly VFR. Scattered thunderstorms along the Nevada
border this evening, with locally heavy rain. Isolated afternoon
thunderstorms in eastern Oregon on Wednesday spreading into
central and southwest Idaho Wednesday evening. Surface winds: W-NW
5-15 kt. Winds aloft at 10k feet MSL: W-NW 10-20 kt becoming SW-W
10-20 kt after 12z.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Thursday night...The upper level
ridge that has been pushed down to our southeast will still be
close enough to help us warm back up in the short term. After
today`s relatively cloudy and cool day, temps will be back up near
100 in the valleys tomorrow and Thursday. Showers and
thunderstorms will continue to form and move generally to the east
through the short term as well. PW values continue to run high,
and this will lead to periods of moderate to heavy rain in the
cores of the stronger cells. An upper level trough will move by to
the north Thursday into Thursday night, increasing winds slightly
and bringing in drier air in its wake. Overall, the largest
changes to the forecast were to increase the chance of
precipitation above NBM guidance. This was largely due to the HRRR
model, which has proven to be quite accurate lately concerning
where/when/how many storms will form and where they will move.
LONG TERM...Friday through Tuesday...Deep moisture will linger
over the area into Saturday, supporting a continued chance of
showers and thunderstorms. Passage of an upper level trough on
Saturday will shift the moisture eastward, bringing a couple of
dry and hotter days for Sunday and Monday. Deep monsoon moisture
returns early next week as an upper ridge axis forms to the east,
putting the region under southerly flow aloft. Temperatures are
near normal Friday and Saturday, warming above normal Sunday into
next week.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
DISCUSSION...KB
AVIATION.....JT
PREV SHORT TERM...SP
PREV LONG TERM....DG
Area Forecast Discussion
National Weather Service Des Moines IA
707 PM CDT Tue Aug 2 2022
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Tuesday/
Issued at 254 PM CDT Tue Aug 2 2022
Key Messages:
-- Heat peaking today; highs still above normal Wednesday into
next week
-- Shower/storm chances tonight through Wednesday
-- Greater uncertainty in forecast Saturday into early next week
Details: The main weather themes over the next 7 days will be the
continued seasonal heat to hot conditions and two precipitation
windows. While there were a few convective clusters near the
forecast area this morning, their cloud cover have not had any
impact on temperatures this afternoon. Highs as of 2pm are into the
90s and upper 90s in a few places and a few places will challenge
100 degrees before the day is over. Overall, the heat advisory
looks good with it expiring this evening. After today, it will
still be hot, but not as hot as today through the end of the week
and likely into early next week. This relatively less hot weather
will be due to an upstream shortwave trough and cold front. At
present, GOES-East upper level water vapor imagery shows this
shortwave trough entering the western Dakotas with a RAP analyzed
100 knot 250mb jet streak. As this trough moves east-
southeastward, it will help to push a cold front through the state
generally after midnight tonight through Wednesday. This front
will bring increasing chances for scattered showers and
thunderstorms. Forecast soundings show a warm boundary layer
keeping any storms elevated tonight, but drier air in the low and
mid-levels could yield a few storms with gusty winds. Recent
convective allowing models suggest these wind gusts would be sub-
severe. The shortwave trough will transit to the east by midday
Wednesday with the front clearing the forecast area by early
evening. With the mid-level support slipping to the east, the
greater severe risk will likely be just outside of our area with
scattered showers and storms as the front moves through on
Wednesday. The clouds and precipitation will help to temper the
heat and while it will still be above normal, highs will be about
5 to 10 degrees lower.
The mid-level ridge over the Southwest US will build a bit eastward
and poleward with a bit of amplification of an upstream longwave
trough entering the northwestern North American continent. This
trough will have a lead shortwave trough, which will bring the next
front and rain and storm chances to the area around Saturday, but
differences remain in timing. The GFS continues to be slower keeping
temperatures higher and conditions drier on Saturday. The 12z CMC is
a bit slower and trending toward the 12z GFS compared to the 00z
run. And finally, the 12z ECMWF is faster bringing the front and
rain and storm chances into the state sooner on Saturday with
current forecast of temperatures being too high if it verified.
Regardless of timing of solution, they seem to be similar with the
boundary laying east to west as it sinks slowly southward into
Missouri either later Sunday or Monday. NBM high temperatures
show large spread between the 25th and 75th percentile from Sunday
onward highlighting uncertainties around the boundary placement
with clouds and precipitation.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 707 PM CDT Tue Aug 2 2022
Mostly VFR conditions during the forecast with south to southwest
winds overnight. Non-convective low level wind shear is expected
late tonight as low level jet intensifies. Scattered showers are
expected on Wednesday across much of Iowa but mostly with VFR
ceilings and localized MVFR visibilities in and around the
showers. Surface winds will become more westerly to northwest
during the day.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for IAZ004-005-015-
023>025-033>037-044>050-057>062-070>075-081>086-092>097.
&&
$$
DISCUSSION...Ansorge
AVIATION...Cogil
Area Forecast Discussion
National Weather Service Grand Forks ND
1021 PM CDT Tue Aug 2 2022
.UPDATE...
Issued at 1021 PM CDT Tue Aug 2 2022
The cold front continues to push over our CWA and this has started
to shift the main axis of elevated instabilty east. Mid level
lapse rates are decreasing behind the front and with decoupling
underway the window for severe has all but shut. There is still
enough elevated instabilty/DCAPE/Shear to at least be concerned
with the potential, however strong CAP and absence of more
organized upper forcing locally has limited initiation. We`ve
been keeping an eye on the north but the activity that initiated
in Manitoba is following the mean wind that will keep it north of
the Northwest Angle. Before the cold front completely moves out
the region tonight a few additional showers or thunderstorms may
develop and latest HRRR runs do shows this potential in the 8-10Z
period, but also supports the idea of this activity being
isolated to widely scattered and weaker immediately along/ahead
of the cold front. Behind the cold front dry conditions should
persist and this is favored at all but our far south and east.
UPDATE Issued at 641 PM CDT Tue Aug 2 2022
Confidence is decreasing in severe thunderstorm initiation as
strong CAP remains in place over much of our CWA. There is still
a remain near the immediate cold front currently where higher ML
CAPE and weakening CIN aligns with enough surface convergence for
possible initiation and this window really is just the next few
hours as mid level lapse rates drop off behind the cold front
(currently pushing over the Devils Lake Basin). Short range CAMs
still show possible initiation in that region just on the other
side of the US/Canada border then tracks this southeast into
northwest MN during the evening. If they can form in this window
then they can remain in the region of better instability and
maintain strong enough updrafts will easterly motion in strong
effective shear to produce severe wind/hail as previously thought.
So far there are no indications of developing CU within that
region (pretty clear actually). As the sun continues to set and
the front pushes east we would likely see the window close on more
robust convection/severe potential if initiation can`t occur in
this window, and any storms would tend to become more elevated and
weaker as stabilization occurs.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 201 PM CDT Tue Aug 2 2022
Thunderstorm chances this evening are still the main forecast
challenge.
As of mid afternoon, a few weaker storms remained over northwest
Minnesota, mainly between Roseau and Blackduck. This activity was
moving to the east at about 30 mph, being fed by the low level
jet, which will continue to shift eastward through the late
afternoon (out of this FA). Temperatures have risen to the mid 70s
to mid 80s, with dewpoints in the mid 60s to around 70. The main
surface low was tracking into southwest Manitoba, with a trough or
dry line extending to its south, just west of a Minot to Bismarck
line. The true cold front was located from far southwest Manitoba
toward the Williston area.
The surface low will push to just north of Winnipeg by 7 pm, with
the trough and cold front somewhere over northeast North Dakota.
By 1 am tonight, the low should be into southwest Ontario, with
the cold front nearly through the entire FA. This will give a
window somewhere in the early evening time frame, where severe
storms are possible over northeast ND into adjacent areas of
northwest Minnesota. Over the past few hours, the various CAMs
continue to show several scenarios. Some have the activity in
southern Manitoba, some have a few cells in our northern FA, and
some show little to no activity. All said, it should be a fairly
narrow window, with the storms moving quickly to the east and out
of this FA by mid to late evening. Northwest winds will get a bit
gusty late tonight into portions of Wednesday. Behind the cold
front, Wednesday highs should mainly be in the 70s with dewpoints
back into the 50s.
.LONG TERM...(Thursday through Tuesday)
Issued at 201 PM CDT Tue Aug 2 2022
Overview...
The overall pattern for the extended period looks to feature mostly
above normal temperatures throughout the remainder of the week
becoming cooler for the weekend, along with increasing storm chances
from Friday onward.
Discussion...
Transient upper level ridging is expected to be in place over the
northern Plains on Thursday. This, along with winds shifting to a
southerly direction, will aid in a rapid warm up to high
temperatures back above normal through the end of the week.
Subsidence aloft should also yield quiet weather for Thursday. By
Friday, there are signals within ensemble guidance indicating that a
shortwave will be traveling through zonal flow aloft. At the
surface, a low pressure system over the Canadian prairies and
attendant cold front look to impact the region Friday. There are
still some questions regarding the timing of the wave and any
resultant precipitation impacts. Regardless, there is increasing
confidence in rain chances, with a conditional threat for
thunderstorms dependent upon timing. Ample shear should be present
across the northern Plains with an advancing jet streak aloft, but
instability will be at a premium, with only a few hundred to 1000
J/kg currently displayed within ensemble guidance.
Moving into the weekend and early next week, periodic chances for
rain and thunderstorms will remain possible as zonal flow aloft
stays in place over the northern Plains. This zonal flow pattern
will be induced by upper level ridging over the central and southern
Plains. As a result, temperatures look to fall into near normal
values during this timeframe. Shower and thunderstorm chances will
be tied to any shortwaves that are able to travel through the upper
level pattern. Resultant confidence in any one of these waves is
low at this time, but the chances will remain possible.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 641 PM CDT Tue Aug 2 2022
While development may still occur this evening as a cold front
drops through the region, the chances for thunderstorms have
decreased. Other than some very light showers in southeast ND and
parts of of northwest MN early in the TAF period (currently on
radar and reported at some ob sites) better chances may remain
near US/Canada border in MN. There are a few pockets of MVFR
ceilings in northwest MN but these shouldn`t prevail as cold front
pushes east-southeast. A more substantial stratus deck is shown
by short range guidance to arrive Wednesday morning mainly in
northwest MN (MVFR) and then clear by midday. Winds through the
TAF period will continue to shift eventually to the northwest
behind this cold front with sustained winds over 12kt and
eventually gusts 20-28kts possible Wednesday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...Godon
LONG TERM...Rick
AVIATION...DJR
Area Forecast Discussion
National Weather Service Grand Rapids MI
746 PM EDT Tue Aug 2 2022
LATEST UPDATE...
Aviation
.DISCUSSION...(This evening through next Tuesday)
Issued at 353 PM EDT Tue Aug 2 2022
- Strong to Severe storms Wednesday?
As typical of these convective situations, there is a fair amount
of uncertainty in how the storms develop and once they do, where
they will go. There will be two complexes of thunderstorms. The
first one develops on the entrance region to a strongly digging
northern stream jet core as it crosses the Canadian border north
of Minnesota this evening. A low level jet with near 50 knots
develops in response to that upper level jet and that will form an
MCS that likely will track mostly east and miss our CWA overnight.
The front trailing the surface low will allow convection on the
trailing end of the overnight convection to progress south during
Wednesday. If nothing else the combination of the outflow and cold
front will allow new thunderstorms to develop by I-96 around noon
and those storms may well become severe. The storms will be out
of the area by late evening.
Locally heavy rain is possible as precipitable water is forecast
to reach near 2 inches, which is in the 95th percentile at this
time of year. This would be with the storms near and south of
I-96.
- Threat for heat Wednesday continues. All of the typical things I
would use to forecast high temperature (1000/850 thickness,
1000/925 mb thickness,850 temps, 925 mb temp and 1000 mb temps
all suggest highs in the mid to upper 90s. The HRRR shows this
too. The only glitch to this is will there be too much cloud
cover for it to get that hot? I am thinking the clouds from the
MCS will not get south of I-96 prior midday.
- It will be windy Wednesday too. That is due to the strong
pressure gradient associated with the system tracking through
the area Wednesday. There is 30 to 40 knots in the mixed layer
Wednesday.
- We expect a repeat of this in the following 3 to 5 days. The
next northern stream wave will do something similar to what
happened over the past 5 days. We get a cool down Thursday into
Friday, then a warm up into Sunday, followed by another system
with a cold front and associated convection.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 745 PM EDT Tue Aug 2 2022
VFR conditions will prevail overnight. Showers and thunderstorms
may be moving into central Lower Michigan between 12Z and 18Z and
then south, reaching AZO to JXN between 18Z and 23Z.
Southwest winds will gust over 20 knots on Wednesday. Higher gusts
to over 40 knots along with brief IFR conditions are possible in
thunderstorms, most likely Wednesday afternoon.
&&
.MARINE...
Issued at 353 PM EDT Tue Aug 2 2022
We have continued the Beach Hazard and Small Craft Advisory
headlines for Wednesday. Given all the wind forecast with this
storm would only make sense. We may need to extend the headlines
through Thursday due the cold air coming into the area at that
time, related to an income surface high.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 5 AM EDT Wednesday through late
Wednesday night for MIZ037-043-050-056-064-071.
Heat Advisory from 1 PM to 6 PM EDT Wednesday for MIZ064>067-
071>074.
LM...Small Craft Advisory from 2 AM Wednesday to 4 AM EDT Thursday
for LMZ844>849.
&&
$$
DISCUSSION...WDM
AVIATION...Ostuno
MARINE...WDM
Area Forecast Discussion
National Weather Service Wilmington NC
840 PM EDT Tue Aug 2 2022
.SYNOPSIS...
Very warm tomorrow with isolated afternoon thru early evening
thunderstorms. Humidity increases later this week and into the
weekend with more typical afternoon and evening thunderstorm
chances as temperatures return to near-normal. Warmer early
next week and slightly drier.
&&
.UPDATE...
Based on latest radar and satellite convective trends across
the ILM CWA and upstream, and the latest HRRR runs, have
lowered POPs and QPF and decreased cloud coverage to mainly
cirrus overnight. Trended latest hrly temps and meshed them to
the stable overnight min temp fcst. 70s sfc dewpoints filling
back in with subsidence no longer drawing down those aftn early
evening 60s dewpoints. Atlantic ridging, sfc and aloft, begins
to flex it`s muscles across the coastal Carolinas during daytime
Wed. Would expect to see a better chance for convection,
especially across the coastal Carolinas, ie especially east of
the I-95 corridor, from midday Wed into Wed evening.
&&
.NEAR TERM /THROUGH TONIGHT/...
Latest surface analysis shows a surface trough inland, which
will be pushing ENE towards the coast tonight. Seabreeze is
noticeable on radar reflectivity, but drier air has inhibited
the convection this afternoon. There remains a slight chance
that some stray shower or thunderstorm could pop along the
seabreeze over the next few hours, but that is unlikely overall.
Mix of clouds and sun tonight, with lows in the mid-to-upper
70s.
Bermuda high edges a bit closer to the coast, and southerly
flow is more pronounced. This increases moisture, with
precipitable water values nearing 2.00 inches again. Piedmont
trough and seabreeze play a role in bringing scattered showers
and storms in the afternoon, a typical summertime pattern.
Another hot day ahead, with highs in the mid-to-upper 90s.
Diurnal mixing likely lowers the dewpoints during the afternoon,
so while heat indices in the triple digits are a given, we
should be saved from Heat Advisory territory (105 or above).
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Convection comes to an end around sunset on Wednesday as
southerly flow increases. Ridge to the west and to the east will
leave an area of weakness between the two over Alabama,
Georgia, and the western Carolinas on Thursday. The bulk of the
rain chances will remain west of the forecast area on Thursday
afternoon, but isolated showers will remain possible east of
I-95. Temperatures on Thursday remain slightly above normal, but
a few degrees cooler than Wednesday with clouds and a better
chance of convection.
Increasing humidity overnight with overnight lows in the mid to
upper 70s.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Bermuda ridge builds into the region late Thursday and Friday
which should limit widespread convection. A few isolated storms
are possible, but the ridge and drier air aloft should keep
chances low. There is still some uncertainty in this forecast at
the moment as models trend toward a stronger and closer mid-
level ridge over the western Atlantic through Friday evening.
Saturday looks to bring the best chance of rain as the mid-
level ridge breaks down and a weakening trough to our north
moves slowly just north of the area, allowing some remnant
energy to approach the eastern Carolinas. Southerly flow
increases on Sunday, but moves inland as the Bermuda high
strengthens offshore. Expect a slow warming trend through early
next week with a return to isolated storm chances.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Mainly VFR thruout the 24 hr fcst period, with subsidence aloft
keeping a lid on convection this evening. Upstream convection
dropping SE should "peter out" by the time it reaches the inland
terminals. Sfc trof dropping to the SE will reach southeast NC
and Northeast SC during Wed morning prior to stalling. This and
the sea breeze will be a convergent source for convection from
midday thru early evening. Still some subsidence aloft but not
as strong as today. As a result, will place VCTS at all sites
lining up with sea breeze and sfc trof locations. Modest SSW-SW
flow will diminish-some and veer to the W to NW as the sfc trof
approaches and the sea breeze slowly dissipates.
Extended Outlook...Periodic MVFR/IFR expected with isolated to
scattered showers and thunderstorms each afternoon and evening
through the upcoming week. Better chance for convection and
periodic flight restrictions this weekend. Possible patchy
MVFR/IFR low stratus and/or ground fog mainly inland terminals
around sunrise each morning late week.
&&
.MARINE...
Through Wednesday... Southwesterly winds at 12-15kts continue,
with gusts up to 20kts. Seas 2-3 ft, following a combination of
a medium period southerly swell and a long period southeasterly
swell.
Wednesday Night through Sunday... Bermuda high will build into
the area over the next several days and the gradient will
weaken. Winds become around 10 knots with gusts to 15-20 knots.
Wind waves generally between 2 and 3 feet through Thursday,
becoming around 2 feet later this week and into the weekend.
Southeast Bermuda swell around 2 feet at 9 seconds.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...DCH
NEAR TERM...IGB
SHORT TERM...21
LONG TERM...21
AVIATION...DCH
MARINE...IGB/21
Area Forecast Discussion
National Weather Service Medford OR
830 PM PDT Tue Aug 2 2022
.UPDATE...Scattered thunderstorms with lightning, heavy rain,
hail and gusty winds developed this afternoon and evening across
Siskiyou and Jackson Counties with isolated to scattered storms
over Klamath, Lake and Modoc Counties. So far, since noon, over
700 lightning strikes have occurred across the area, many fell
with rain. Several severe thunderstorms were detected via radar
and warned for in Siskiyou and Jackson Counties. High moist
content in the atmosphere led to efficient rain rates with these
storms. High rain rates combined with slow storm motion, result in
heavy rainfall of 1 to 4 inches falling with some storms. Water,
mud and rocks were reported as impacting several roads including
highway 97 northwest of Weed and near MacDoel and Highway 3 west
of Yreka. Also flash flooding affected the eastern portion of the
McKinney fire. Flash flood warnings were issued for areas.
Thunderstorm activity is beginning to decrease in intensity and
coverage. However, additional thunderstorms are occuring this
evening, mainly in Siskiyou and Jackson Counties with some
isolated storms also east of the Cascades. Thunderstorms will
continue into late this evening, then are expected to diminish.
&&
.AVIATION...03/00Z TAFs...Conditions will be VFR at KOTH this
afternoon before lower ceilings and vis in marine stratus and fog
return in the evening.
Isolated thunderstorms remain the main concern into this evening
that could produce gusty and erratic outflow winds, frequent
lightning and small hail. Also keep in mind gusty and erratic winds
are also a concern outside of the core of thunderstorms.
Thunderstorms should begin to dissipate between 3-4z, but it`s
possible a few could linger as long as 5z. General movement of
storms are expected to be southwest to northeast and will tend to be
slow movers. Medford and possibly Klamath Falls are expected to be
at highest risk of storms until 3-4z.
Once the storms end later this evening. VFR conditions are expected
for the remainder of the TAF period. However we could be dealing
with another round of isolated storms after 21z. -Petrucelli
&&
.MARINE...Updated 820 PM PDT Tuesday, 2 August, 2022...Light to
moderate north to northwest winds will persist through Wednesday as
an offshore low drifts westward. North winds are then likely to
increase Thursday, likely to reach advisory levels, as a thermal
trough develops and strengthens. Seas are likely to continue to
build and become steep across most areas and possibly very steep
south of Gold Beach Thursday evening into Friday.
Additionally, marine layer fog will reduce visibilities across the
coastal waters, especially during the night and morning hours, and
could become dense. -Miles/Petrucelli
&&
.PREV DISCUSSION... /Issued 442 PM PDT Tue Aug 2 2022/
SYNOPSIS...Southern Oregon and northern California is between a
ridge of high pressure over the four corners region of the US a
persistent low pressure system around 140W near the
California/Oregon border. Our pattern will include chances of
thunderstorms over the next couple of days in the afternoons and
evenings as well as warmer temperatures this weekend. Overall,
this pattern is expected to linger for a while.
Key Points:
*Thunderstorms will be capable of producing gusty winds to 50 mph,
small hail, abundant lightning, and very heavy rainfall.
*Periods of heavy rainfall may create flash flooding, debris
flows, and rock falls over area wildfires and recent burn scars
in steep terrain. See the FFAMFR for more details.
*Temperatures will be increasing this weekend and will be hot once
again with warm overnight lows.
*Smoke may create periods of degraded air quality. Please see the
AQAMFR for more details.
DISCUSSION...The layer of clouds this morning have lifted
allowing ample surface heating to occur this afternoon and
evening. With less smoke from the McKinney fire over the Rogue
Valley, expect a much larger area of thunderstorm chances today.
The areas of concern for the most abundant lightning are
highlighted in the RFWMFR (Red Flag Warning), but more information
on that will be highlighting in the fire weather discussion
below.
High resolution ensembles have been showing thunderstorms
developing this evening across the area, and have been sowing
gusty winds to 50 mph and small hail. We`re already seeing outflow
boundaries drift distances from their thunderstorms on RADAR, so
it vitally important for folks to pay attention to the radar; and
firefighters should be checking in with their safety officers
relatively frequently.
It is also worth noting that the Precipitable water value in the 5
AM sounding this morning was 1.82 inches. This is exceptional for
our area, and it suggests periods of very heavy rain. The incident
meteorologist at the McKinney fire mentioned a couple of debris
flows on Sunday when area observations showed around a half an
inch of rainfall. With the potential for similar conditions this
evening, have coordinated with them to issue a flash flood watch
for the fires and the River Complex burn scar in Siskiyou County.
Thunderstorms should generally dissipate overnight, and the
influence of the low should diminish, leaving less chances for
thunderstorms on Wednesday-Friday. With the ridge of high pressure
becoming more dominant, expect temperatures to be increasing as
well, particularly for this weekend. It is a bit early to be
pinning down any heat-related headlines; but it is important for
interests in those areas to keep an eye on it for the weekend.
Smoke could make this part of the forecast a bit more difficult,
but the HRRR smoke model is not currently showing exceptionally
robust smoke. This could change depending on how area fires pick
up once things begin drying out. Therefore, Oregon DEQ reminds us
to prepare for periods of degraded air quality as they continue
their air quality advisory for Jackson and Klamath Counties
through Friday.
The other difficulty in the forecast will be how tropical moisture
from Frank (or the current impulses coming off of Mexico) moves
northward. Should our low wobble a little bit farther north, we
could see additional chances of thunderstorms over the weekend
into next week. These are not in the forecast at the moment, as we
have gone with the National Blend of Models which shows a very
reasonable solution for this pattern. Please keep an eye on the
forecast for changes. -Schaaf
Additionally, marine layer fog will reduce visibilities across the
coastal waters, especially during the night and morning hours, and
could become dense. -Spilde/DW/Miles
FIRE WEATHER...200 PM PDT Tuesday, 2 August, 2022...Just over
2000 lightning strikes were recorded since around 2 pm yesterday
(Mon 8/1), and over half of that occurred after 11 pm last night.
Precipitation has been recorded with these storms, ranging from a
quarter of an inch up to over half an inch. However, there were
lightning strikes outside of the precipitation fields/cores.
Fortunately, humidities have been higher across the region, and
until the moisture flow begins to get cut off tomorrow, they should
remain high with moderate to good recoveries likely tonight.
Isolated to scattered thunderstorms are expected again today from
western Siskiyou County, Josephine County, and eastern Douglas
County eastward, with the focus of activity from the Siskiyous south
and eastward. A Red Flag Warning remains in effect until 11 pm
tonight for abundant lightning on dry fuels in these areas. Frequent
lightning, gusty outflow winds, and locally heavy rainfall are all
possible with these thunderstorms and localized severe thunderstorm
warning level wind gusts around 60 mph will be possible. This
morning, the available moisture in the atmosphere over the region
once again recorded a record daily high, and as a result, we suspect
most storms will be wet, and could produce periods of heavy rain. If
this occurs over a recent burn scar, or an ongoing fire, debris
flows are a concern. Storms should not be stationary, which is
likely to help in this regard, and storm motion today will be more
southwest to northeast as the upper level flow shifts slightly to
more westerly than southerly.
The low pressure responsible for bringing the moist unstable air
will retreat southwestward today and the Four Corners High will
expand westward Wednesday into Thursday. This will bring the return
of hot temperatures (upper 90s West Side/upper 80s to low 90s East
Side) and bring a more westerly (stable/drier) flow regime to areas
west of the Cascades. This will keep thunderstorm potential for the
remainder of the week across the eastern and southern portions of
the region. In the meantime, another low pressure from the northwest
will move across the Canadian Providences Wednesday into Thursday.
While this will moderate temperatures some, it could bring some
gusty winds to the region, especially east of the Cascades where
guidance suggests gusts of 25 to 35 mph. While it doesn`t look like
humidities will be a concern with these winds, the concern lies with
the potential for any hold over fires.
Heading into the weekend, there are several unknowns that could make
big differences in the forecast. While the ridge and southerly flow
should trend temperatures warmer overall, there is the potential for
another upper level trough to pass through the region during the
weekend, while the offshore closed low could begin to track back
towards the coast. Meanwhile, some models are also suggesting that
tropical energy/moisture from the remnants of Tropical Storm Frank
could filter up into our area, and this would produce the potential
for more thunderstorms. Confidence in the behavior of any of these
factors is low, especially when considering how they would interact,
but there is the potential for interesting, perhaps impactful,
weekend weather. -BPN/BR-y
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 11 PM PDT this evening for
ORZ617-620>625.
CA...Red Flag Warning until 11 PM PDT this evening for
CAZ280>282-284-285.
Flash Flood Watch until 11 PM PDT this evening for CAZ080-081.
Pacific Coastal Waters...
None.
$$
CC/CC/CC
Area Forecast Discussion
National Weather Service Marquette MI
722 PM EDT Tue Aug 2 2022
.SHORT TERM...(Into Early Evening)
Issued at 328 PM EDT TUE AUG 2 2022
High pressure over Upper Michigan has kept much of the fcst area dry
through early afternoon. However, now there is some shra/isolated
tsra reaching into the IWD area in the past hr along a MUCAPE
gradient of 500-1000 j/kg situated just to the southwest. Increasing
WAA at the nose of a 30-35 kt LLJ along with mid-level lapse rates
of 7-7.5C/km will also support isolated tsra into the late
afternoon/early evening hours. RAP model does indicate effective
shear increasing near 50 kt between 22-00Z which could maybe support
a stronger to marginally severe storm into the far western counties
as well. Elsewhere across the west half, expect mainly just isolated
to scattered showers into early evening with mainly dry conditions
east half. High temperatures should generally range from the mid to
upper 70s to the upper 70s and lower 80s west half.
.LONG TERM...(Tonight through Tuesday)
Issued at 311 PM EDT TUE AUG 2 2022
A subtle shortwave moving across MN with a surface warm front
lifting into the area will be the main focus for tonight. Along the
warm front, elevated thunderstorms look possible given the steep mid-
level lapse rates, healthy MLCAPE of 1000-3000j/kg (more if you
believe the NAM), increasing 925mb LLJ to 30-45kts, and deep layer
bulk shear of about 50kts. With this setup, thunderstorms could be
strong to severe, and capable of producing strong winds and large
hail. Timing among the guidance suggests the warm front lifting in
late this evening with showers/storms developing evening/overnight
CAMS evolution of the event pings the greater thunderstorm coverage
over Lake Superior early on as remnants from MN moves over the
water. Across the UP, the same guidance suite is suggesting spottier
coverage initially in the west/central until around sunset when the
LLJ ramps up. From there, there seems to be a signal of thunderstorm
clustering with isolated supercells embedded within and an eventual
evolution into a pseudo-linear segment extending from northeastern
Lake Superior southwestward into WI, moving southeast toward the St.
Mary`s, Lake Michigan, and lower Michigan. With that said though,
some of the recent CAMS runs are suggesting much of the activity may
have difficultly organizing overnight and may remain a broken line.
Deterministic guidance suggests PWATS could increase to around 1.8
to 2 inches. Not only does this suggest heavy rain could be possible
in any thunderstorm tonight, but it also means folks should expect a
warm and muggy night across the UP. Some places in western Upper
Michigan and near Lake Superior could stay in the low 70s while the
cooler spots only dip into the mid 60s. Another thing to consider
with the amplifying LLJ is that surface winds of 25mph will be
possible tonight, and maybe near 35mph at times in downslope areas
near Lake Superior.
A cold front tied to the parent surface low moving into Ontario will
move through the region on Wednesday. Destabilization aided by
dinural heating could work to re-invigorate shower and thunderstorm
activity ahead of the boundary in the central/eastern UP during the
day, but should be east of the forecast area by Wednesday evening.
Strong to severe weather isn`t expected in this second round, but
some thunderstorms should be expected. Additionally, until the cold
front clears, southerly winds of 25 to 30 mph will be possible at
times, mainly in the east and west to northwest winds to increase to
25 to 35 mph, particularly in the Keweenaw along the boundary.
High pressure building in behind the cold front will dominate the
Upper Great Lakes Thursday and Friday. The cooler airmass aloft will
support more seasonable temps on Thursday, but as the high shifts
east of the region, promoting southwesterly flow and WAA, we`ll
likely see a return to the 80s for most, with some near 90F spots
possible in the west. The next system looks to swing through this
weekend, but there`s notable timing differences among the
deterministic and ensemble systems.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 722 PM EDT TUE AUG 2 2022
Showers and thunderstorms continue to overspread the western TAF
sites this evening, and shower activity will reach KSAW before 02Z.
With the heavier convective activity ceilings and visibilities will
drop into the MVFR range at times. There is still the potential for
some severe thunderstorms this evening and early overnight over the
west as a 40 kt LLJ develops over the western U.P. this evening,
which will need to be monitored over the next several hours.
Otherwise the LLJ will persist overnight. Winds will increase from
the SW late tonight and Wednesday prior to the passage of a cool
front, with the front veering winds to the W over KCMX and KIWD late
in the forecast. Occasional gusts to near 20 knots will occur this
evening and overnight at the western TAF sites, with gusts up to 30
knots possible at KCMX in tomorrow afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 312 PM EDT TUE AUG 2 2022
Warm front lifting into the region tonight will support showers and
thunderstorms over Lake Superior. There is the potential for some
strong or even severe thunderstorms. Additionally overnight, an
intensifying LLJ and WAA will limit that strongest winds from
reaching the surface, save for known convergent and downsloping areas
near the lakeshores. With that being said though, higher reporting
platforms can expect wind gusts in the 30-35kt range. Confidence is
low on how much could mix down to 10m or to anemometer height given
the increasing marine layer stability, so a gale warning wasn`t
issued.
The parent low is expected to move through Ontario Wednesday,
dragging its cold front through the lake during the day. Along and
just behind the front, winds become westerly to northwesterly and
could increase again to near 30kts. High pressure building in
after the front will provide mostly light winds Thursday and
Friday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JTP
AVIATION...RJT
MARINE...JTP
Area Forecast Discussion
National Weather Service Riverton WY
420 PM MDT Tue Aug 2 2022
.SHORT TERM...(This Afternoon through Wednesday Night)
Issued at 156 PM MDT Tue Aug 2 2022
Enough breaks in the cloud cover to allow for the development of
isolated thunderstorms across the far south early this afternoon.
The nose of an upstream jet streak has also reached southwest
Wyoming, which should aid convection through the afternoon hours. As
thought possible, extensive cloud cover has hindered destabilization
and slowed generation of more widespread showers and storms. The
first shortwave over central Wyoming exits the area by mid-afternoon
with the next on its heels. Already noting thunderstorms forming in
central and eastern Idaho, a trend that the HRRR has well
captured. CAMS indicated this area of convection to bring a better
chance of heavier rain with showers and thunderstorms between
about 3 PM and 10 PM Tuesday. Precipitable water values around 0.9
inches, so heavy rain is the primary hazard. Resident time over
any one location should be limited given westerly steering wind
around 20 mph. Lingering mid-level moisture behind this second
shortwave coupled with weak jet-level support may still allow for
lingering light showers over the west-central mountains into early
Wednesday morning.
Drier air filters into the forecast area from the northwest late
tonight and Wednesday morning. This shunts the best moisture to
central Wyoming Wednesday, where isolated afternoon showers and
thunderstorms develop. Preferred locations off the southern end of
the Absaroka Range and the Wind River Range the most likely genesis
locations. However, isolated convection also looks possible over the
Teton Range and Casper Mountain. Precipitable water values drop
back to more seasonal levels, so heavy rain does not pose a
problem. Lacking dynamic support, the showers and storms wane
quickly with the loss of solar heating Wednesday evening. More
sunshine and a rebound in mid-level temperatures allow for
daytime highs to rise to seasonal averages. Wednesday night is
dry regionwide.
.LONG TERM...(Thursday through Tuesday)
Issued at 156 PM MDT Tue Aug 2 2022
The flat ridge will continue over the area with a gradual switch to
southwesterly flow as the next major trough moves onshore in the
Pacific NW. Thursday will see very isolated convective activity
across the west, with the east staying dry and a bit warmer. There
will be a stronger gradient ahead of a cold front on Thursday
afternoon for gusty southwest winds, gusting up to 30 mph. Friday
allows for the next trough to push some showers across the west and
then across the entire area once again. The cold front will move
into the area and keep the increased pressure gradient and gusty
southwest winds, especially in the normal wind prone locations.
Gusts up to 30 mph possible Friday, and again on Saturday afternoon
as well. Saturday will also see convective activity, mainly in the
afternoon and evening.
The weather pattern for Sunday into early next week is still up for
grabs between the models. There still looks to be enough moisture
and daytime heating to allow for afternoon and evening convection on
those days, but extent and strength is unpredictable at this time.
Temperatures will stay near normal values, to just above through the
long term period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday)
Issued at 410 PM MDT Tue Aug 2 2022
The terminals will see VFR conditions through the period, unless
they are directly impacted by a stronger thunderstorm. Here MVFR
conditions will occur briefly due to heavy rain. The showers and
thunderstorms will move eastward through the evening, clearing from
west to east. Most of the activity will dissipate by around 06Z.
Gusty southwest winds at some of the TAF sites will diminish after
around 02Z.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC
for the latest information on icing and turbulence forecasts.
&&
.FIRE WEATHER...
Issued at 156 PM MDT Tue Aug 2 2022
Extensive cloud cover and embedded rain showers have substantially
cooled temperatures from those of the last few days. Another round
of showers and isolated thunderstorms arrives from the west late
Tuesday afternoon and tracks east through the evening. The best
chance for wetting rain will be across the Teton Interagency
Dispatch Area. The showers diminish overnight with only lingering
showers over the north and central zones. Drier air pushes in from
the northwest late tonight and Wednesday. This drier air shunts
any remaining moisture to the central zones where isolated showers
and storms occur Wednesday afternoon and early evening.
Temperatures do rebound to seasonal readings Wednesday given more
sunshine. Dry conditions prevail regionwide Wednesday night and
Thursday morning. Increasing southwest flow aloft will boost
temperatures and wind speeds Thursday afternoon. Daytime highs
again rise to about 5F above normal. As for Thursday wind, 15 to
25 mph speeds are anticipated in the mountains and zones 279, 289,
and 280. Speeds over the northwest mountains will be a touch
higher with gusts to 35 mph possible late Thursday. The best
chance for Thursday afternoon showers and storms will be across
the western mountains. The rising temperatures and gusty wind
combine to allow for very good to excellent smoke dispersal for
most if not all zones Thursday. Taking a peek at Friday,
conditions look cooler with a better chance of showers and
thunderstorms, at least along and west of the Continental Divide.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CNJ
LONG TERM...Swanson
AVIATION...Swanson/AR
FIRE WEATHER...CNJ