Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/21/22
Area Forecast Discussion
National Weather Service La Crosse WI
1057 PM CDT Sat Aug 20 2022
.DISCUSSION...(Tonight through Saturday)
Issued at 240 PM CDT Sat Aug 20 2022
Key Messages:
- Late afternoon showers/isold storms - diminishing
- Fog Potential Tonight - maybe dense?
- Drier Sunday, into the start of the work week
- Rain chances for the 2nd half of the new week
* SHOWERS/STORMS: this afternoon, ending early evening
Scattered showers and a few storms continue to spark around an area
of low pressure over eastern IA and in a region of 1000 J/kg of
MLCAPE. Locally, most of the activity has held across NE IA/SW
WI...and generally just showers with little if any thunder. Shear is
meager at best. Expecting the showers (storms?) to persist through
the rest of the afternoon, holding mostly in the same locations,
ending with the loss of heating. A few could produce brief, locally
heavy downpours. In addition, due to the location of the sfc low,
some cold air funnels have been reported mostly south of the local
forecast area. That said, can`t rule out a few venturing into
Fayette, Clayton and Grant counties. These generally don`t reach the
ground, but will keep a close eye on radar.
* FOG: potential for dense fog late tonight
Patchy to areas of dense fog developed over portions of the
Dakotas/northwest MN early this morning, under clear skies and the
influence of a weak sfc high.
The high is progged to ease slowly eastward tonight, looking to
center itself over central MN. With T/Td spread relatively low from
cooler temps, cloud cover...along with recent rains helping low
level saturation...expect more fog to develop under the ridge
tonight. Most of the impact will be across MN. Locally, how far
eastward dense fog could spread will depend (greatly) on the
clearing and where the high sets up.
Current cloud shield has some diurnal elements to it, and expect
some break up with loss of daytime heating. Clearing from west to
east looks like a good trend this evening...but meso models looking
to push low saturation/stratus clouds back west/southwest overnight
as low level flows goes northeasterly. With fog likely under the
locations with clear skies, how far west the stratus makes it has
obvious impacts on the potential for dense fog. Unfortunately, this
isn`t clear.
Will add fog mention to parts of SE MN where confidence in higher
for potential higher impacts. Dense fog advisories could be needed
SE MN and other locations, depending on how the cloud scenario plays
out.
Elsewhere, could see some patchy pockets of fog but the potential
for thick, impactful fog (1 mile or less) looks less likely given
the higher probability for lingering clouds/low stratus.
* START OF NEW WEEK: drier, some sunshine
The upper level trough/low gets a bit of a push east later tonight,
being undercut by 300 mb jet max and then encroachment of a ridge
over the plains. It`s not a quick exit though and could have spotty
showers linger in the east into early evening, with the cloudy
conditions not fully clearing east until later in the day Sunday.
All in all though, the recent spate of showery days will be coming
to an end.
Weak upper level ridging bends eastward from the northern plains
tonight, although the axis still holds off to the west. A sfc high
does meander in by Sunday night, and will wobble across the region
through Tue. Some hints in the models that a few ripples in the
upper level flow could track across the region Tue, but not much
else for forcing, nor much saturation to work with (per RH fields).
Will stay the course with a dry start to the new week - along with a
welcome return of some sunshine.
With the loss of the upper level low and its cloud/rain showers, a
return to more seasonable temps is expected.
* RAIN CHANCES: second half of the new week
Upper level flow looking to become more zonal for the later half of
the new week, with the GFS and EC sliding various shortwaves/ripples
in this flow west to east across the region. A lot of variety with
timing - location - strength of these features between the models.
That said, the trends play up some rain/storm chances here and
there. Will let NBM detail these chances for now.
As for temps, looking to stay fairly seasonable as any significantly
warmer air holds with the ridge over the west coast/rockies.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1057 PM CDT Sat Aug 20 2022
The combination of the departing area of low pressure over
Illinois and the incoming area of high pressure over northwest
Minnesota will maintain a light north to northeast flow overnight.
IFR/MVFR ceilings are already developing in an area of higher
moisture west of Lake Michigan with the RAP showing this
expanding/spreading west through the night. This is expected to
bring these low ceilings into both sites along with some
visibility reductions from fog. All this should burn off pretty
quickly Sunday morning with VFR conditions expected to return
during the last half of the morning.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Rieck
AVIATION...04
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
929 PM CDT Sat Aug 20 2022
.UPDATE...
Issued at 928 PM CDT Sat Aug 20 2022
Quiet weather continues for the late evening update. No major
changes needed.
UPDATE Issued at 545 PM CDT Sat Aug 20 2022
No major changes were needed for this update. High pressure
continues to dominate the weather pattern this afternoon and into
the evening. Just blended in the latest observations to the going
forecast.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 215 PM CDT Sat Aug 20 2022
The main highlights this period are the more seasonable
temperatures and mostly sunny conditions.
The rest of today:
The diurnal cumulus clouds will continue through sunset. On
satellite you can see the clouds wrapping around the southern end
of the surface high pressure located in northern North Dakota.
Light and variable winds from this high pressure will continue
through the night, with clear skies.
Sunday:
The potential for patchy fog in the southeast and south central
exist early in the morning. RAP relative humidity at 925mb are high
between 07z-14z. The fog will mostly be south of Interstate 94.
Temperatures will climb into the 80s in the east, and low 90s in
the west where the thermal ridge nudges into the area. Winds will
be out of the south, gusting around 15 to 20mph in the west.
Expect more diurnal cumulus in the afternoon again. The upper
level pattern will turn zonal through the day as the top of the
ridge will flatten.
.LONG TERM...(Sunday Night through Saturday)
Issued at 215 PM CDT Sat Aug 20 2022
Chance for showers and thunderstorms everyday this week is the
main highlight. The upper level pattern will stay somewhat flat
through the week, with disturbances moving through bringing the
rain chances.
Rain:
The chance for showers and thunderstorms starts late Monday night
into Tuesday morning. As of now the chance is only 20 percent. The
next round is Tuesday afternoon through Thursday from multiple
little waves moving through the ridge. Widespread rain chances of
40-55 percent and around a 20 percent chance of thunder with those
showers. A Colorado Low and upper level shortwave trough looks to
move through starting Friday. The main rain chance looks to be in
the west around 30 percent. Then Friday overnight the rain will
slide east and exit the area by late Saturday morning. The slight
chance (15-20 percent) will remain through the afternoon in the
central and east. All of this of course has uncertainty, and
will have a more clear picture on timing as the week progresses.
Temperatures:
Highs through the week will start seasonable in the 80s and 90s,
with the influence of the thermal ridge. Tuesday will be the last
day of the forecast period with temperatures in the 80s and 90s.
After Tuesday the upper level flow turns slightly northwest and
shoves the thermal ridge south. This will allow for cooler
temperatures down in the mid to upper 70s through the end of the
week. The aforementioned low and shortwave will help pull the
cooler temperatures south from Canada Friday and Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 545 PM CDT Sat Aug 20 2022
VFR conditions are expected for most of western and central North
Dakota through the period. The one exception could be across the
far south central and southeast late tonight through early Sunday
morning. Here we are expecting some patchy fog to develop which
could lead to some MVFR or brief IFR visibility observations.
Most of the fog should stay south of the I-94 corridor, but
there`s a small chance it could make its way up to KJMS and KBIS.
Fog will dissipate mid to late Sunday morning.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...ZH
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...ZH
Area Forecast Discussion
National Weather Service Grand Forks ND
1009 PM CDT Sat Aug 20 2022
.UPDATE...
Issued at 1008 PM CDT Sat Aug 20 2022
Latest HRRR indicates main fog chances east central South Dakota
northeast toward Duluth and NW Wisconsin. Will keep patchy fog
day shift put in the fcst for SE ND and WC MN as despite HRRR
forecast see no reason to discount some patchy fog in that area.
UPDATE Issued at 705 PM CDT Sat Aug 20 2022
Remainder of the CU will dissipate at sunset leaving a clear sky
overnight. Idea of patchy fog seems reasonable and will keep as is
in the forecast (SE ND into MN lakes country).
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 317 PM CDT Sat Aug 20 2022
The short term period will feature generally quiet weather and
seasonable temperatures. Main forecast challenges will be sky cover
this afternoon and the potential for fog development across
southeastern North Dakota and west central Minnesota overnight into
early Sunday morning.
Discussion...
With upper level troughing pushing eastward from the Midwest toward
the east coast, upper level ridging will be in place over the
northern Plains. High pressure at the surface and strong subsidence
aloft will stymie any impactful weather across the short term. Some
cloud cover will persist today as convective temperatures have
generally been met across the region, resulting in some Cu
development. This cloud cover should begin to diminish in the
evening as diurnal trends subside.
With high pressure in place over the region through the overnight
hours, radiational cooling should take place. This will result in
cool overnight lows in the 50s once again. Given the likely presence
of clearing skies and generally calm to light winds, some patchy fog
may develop across the region as well. At this time, spatial
coverage is difficult to determine, but best potential looks to be
across southeastern North Dakota into west central Minnesota where
ingredients look more primed to come together at this time. As the
sun rises, look for any fog that does develop to diminish by early
to mid Sunday morning. With upper level ridging persisting into
Sunday, temperatures look to respond in kind. As a result, highs
should manage to reach the low to mid 80s under mostly sunny skies.
.LONG TERM...(Monday through Saturday)
Issued at 317 PM CDT Sat Aug 20 2022
The probability for impactful weather is low through the long range
periods.
Large scale pattern will feature a deepening Hudson Bay upper low
and strengthened monsoonal ridge across the southwest CONUS by the
end of next week, and there is strong ensemble clustering towards
this general pattern. This places our CWA under predominant NW flow
through much of next week, with falling heights at 500MB through the
end of the week. We will still be under the influence of shortwave
ridging aloft through Tuesday, supporting predominantly dry
conditions and warmer temperatures in the 80s. This is still within
seasonal ranges though a bit above "average".
A mid level shortwave trough drops south along the western edge of
the Hudson Bay low by Tuesday night into Wednesday, and an
associated front slowly slides south over our CWA. Spread in
evolution/coverage is still relatively high but there is still a
good signal for precip chances (current NBM still int eh 40-50%
range Tue night). Track/pattern does limit moisture return and
instabilty potential and strong/severe storms are not currently
favored. Still, there is enough instability indicated to support
embedded thunderstorm potential.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 705 PM CDT Sat Aug 20 2022
VFR thru the pd. Light winds tonight, clear. Few CU forming with
daytime heating Sunday with a more southwest wind 5 to 12 kts
developing. Patchy ground fog late tonight/early Sunday with high
over northern MN. Though most favorable conditions look to be more
NE into central MN.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...Riddle
SHORT TERM...Rick
LONG TERM...DJR
AVIATION...Riddle
Area Forecast Discussion
National Weather Service Green Bay WI
1031 PM CDT Sat Aug 20 2022
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 244 PM CDT Sat Aug 20 2022
The latest RAP analysis and satellite/imagery show an upper level
low pressure system spinning over the western Great Lakes and a
cold front dropping south across northern Minnesota and Lake
Superior. Clouds are plentiful region-wide, but partial clearing
across southern Wisconsin/northern Illinois and far northern
Wisconsin/Upper Peninsula has helped mixed layer instability up to
1000 j/kg develop. Consequently, scattered thunderstorms
developed by early afternoon across these areas. Besides far
northern Wisconsin, some storms may also move into east-central
WI later this afternoon from the south. No severe weather is
expected due to weak shear aloft, but a few strong storms could
produce brief gusty winds, small hail, and heavy downpours.
Tonight...The upper low will continue to move east-southeast
across Lake Michigan and into Lower Michigan. Thunderstorms will
diminish early in the evening with rapidly waning instability, but
a few light showers or drizzle could linger well into the
overnight hours as low level flow turns northeast off Lake
Michigan. Further northwest, partial clearing will arrive late,
but guidance remains bullish for low stratus and mist to develop
over central and north-central WI. Lows will be ranging from the
middle 50s to lower 60s.
Sunday...Clearing will continue to slowly move in from northwest
to southeast during the day. Northeast winds will likely continue
to augment low level moisture over northeast Wisconsin in the
morning, which could lead to a few more light sprinkles or
drizzle. Then clearing should work into northeast WI in the
afternoon. Highs ranging from the middle to the upper 70s.
.LONG TERM...Sunday Night Through Saturday
Issued at 244 PM CDT Sat Aug 20 2022
Northwest upper flow should produce dry and seasonable
weather for most of next week.
The two exceptions are Wednesday night and Thursday, when an upper
trough and surface cold front could bring some showers and
thunderstorms, and again Saturday night and Sunday as the upper
flow becomes southwest, and a upper trough and surface warm front
approaches from the Plains states.
Temperatures should be within a few degrees of normal on most days.
Wednesday will likely be the warmest, as far as max temperatures
and humidity goes.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1029 PM CDT Sat Aug 20 2022
Cigs and vsbys remain the main aviation forecast issue late this
evening. An expanding area of ST dropping SW from Upper Michigan
suggests the ST will be more of an issue than the fog. But will
opt for a TEMPO group with some lower vsbys as patchy dense fog
will be possible--especially before the ST settles across the
entire area.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1038 PM EDT Sat Aug 20 2022
.SYNOPSIS...
A moist stationary front will linger over the region through
tonight. Then a weak cold front will push into the area Monday and
settle along the Carolina coast Tuesday. Weak high pressure will
move in behind the front, but enough moisture will remain to keep
chances for showers and thunderstorms in place each day through
the end of the week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1035 PM EDT Saturday: A few patches of light rain left
over from earlier convection, but otherwise we are entering an
apparent lull in the activity. Still have sfc-based CAPE values
in the 500-1000 J/kg range across the region, with the usual
nighttime inhibition, so there remains some fuel available for
nocturnal convection. We await upstream convection seen across
north AL/central GA.
Throughout the rest of the near term forecast, an upper-level
low over the Midwest will track east over the Great Lakes region
while gradually opening up into an upper-level trough. Meanwhile,
the subtropical ridge will remain out in the western Atlantic,
extending into the Gulf of Mexico. A series of mid-level shortwaves
will track along the base of the upper-level trough in place over
the Southeast, while a 250 mb jet approaches from the west. This
will act to enhance precip chances late tonight into Sunday. Model
soundings show SBCAPE lingering overnight into Sunday morning,
ranging from ~500-1000 J/kg. Recent runs of the HRRR have toned
down the coverage overnight, so the fcst was cut back mainly to
the chance range until the pre-dawn hours when we ramp it back up
from west to east into daybreak Sunday. Painted the entire CWA with
likely PoPs the rest of the near term forecast period. With SW`ly
flow in place, PWAT values look to range from 1.5-2.0 inches across
the fcst area overnight Sunday into Sunday afternoon. This could
lead to locally heavy rainfall for areas that see heavy downpours
repeatedly track over the same areas. However, any hydro issues look
to remain low with only about 0.50 to 0.75 inches of rain expected
across much of the CWA. Isolated areas may see 1.00 to 1.50 inches
of rainfall where the heavier downpours track. Currently the QPF
looks best across the mountains. With cloud cover in place tonight,
expect lows to be ~4-7 degrees above climo. High temperatures
Sunday should be be 2-4 degrees below climo thanks to precip and
cloud cover.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 230 PM EDT Saturday: An upper-level trough will slowly
propagate east over the region as an attendant cold front enters
the Tennessee Valley on Monday. As the weak cold front enters
the Appalachians Monday morning, the airmass ahead of it across
our forecast area will be moist and modestly unstable with
PWs slightly above normal and SBCAPE values of 500-1500 J/kg.
The upper-level trough will sustain 15-25kts of bulk shear and
provide weak synoptic-scale forcing, though the best DPVA will
remain well to our north. Therefore, the forecast continues to
advertise scattered to widespread showers and thunderstorms across
the area during most of the day on Monday, but the pattern supports
neither a significant QPF nor a severe thunderstorm threat. While a
one or two strong thunderstorms are possible, we expect Monday
to be unsettled, but unexciting. Cloudy skies and precipitation
will continue to suppress afternoon highs, which will be about
4-6 degrees below normal. As the front slowly marches east Monday
afternoon into the evening, expect cloud cover and PoPs to gradually
decrease from west to east.
Winds will gradually veer to the NW as the front slowly moves
across the Piedmont Monday evening and overnight. The continental
airmass immediately behind the front will be drier and more stable,
but the front should stall near or over the southern portions of
our area (lower Piedmont) on Tuesday. Therefore, north and west
of the front, the airmass will suppress nearly all shower activity
for Tuesday, save for isolated showers along favored ridgetops.
Closer to the front over the lower Piedmont, low-end chance PoPs
are maintained for isolated showers and a general thunderstorm
or two. Ironically, high temperatures should be a couple of
degrees warmer than Monday under partly to mostly sunny skies and
weak downslope flow.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 230 PM EDT Saturday: As the upper-level trough from the
short-term deamplifies and lifts NE, the region will remain under a
weakness in the pattern through the extended. The next shortwave
trough will drop into the Ohio Valley on Wednesday and weaken as
it lifts NE into the Mid-Atlantic for Thursday, leaving behind a
shear axis over the Southeast heading into Friday and the weekend.
While it will not create a significant weather threat at any point
during the period, the pattern will keep our weather unsettled.
The cold front that moved through the area during the short-term
will stall then meander over the Carolinas as a weak trough axis.
It will provide some weak low-level convergence to support diurnal
convection, but it will be increasingly ill-defined with each
passing day. With the upper-level shear axis in place heading
into Thursday and Friday, the deterministic guidance is suggesting
weak shortwave energy may enhance bulk shear over the Carolinas
to support a better chance for a few strong thunderstorms at
that time. Overall however, showers and thunderstorms look to
be garden variety each day. A persistent Atlantic moisture flux
will sustain above-normal PWs through the extended, but without
deep-layer forcing, the heavy rainfall threat will remain isolated
at best each afternoon. Thicknesses will increase slightly
behind the early week trough, but temperatures are expected to
remain slightly below-normal to near normal through Saturday as
upper-level ridging stays well to our west and east.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR prevailing into the early morning
hours. Precip coverage will increase from the west along with an
increase in low level moisture that should force the development of
more extensive low clouds from west to east after 07Z. The latest
guidance suggests a wave of showers and thunderstorms moving east
across the region through the morning hours, so the TAFs will
feature either TEMPO or PROB30 to handle the most likely timing of
restrictions. Wind will be light S to SW. After the first wave of
activity moves through, low clouds should scatter out, but could
just as easily hang around at the MVFR or low VFR level well into
the afternoon. Additional showers and storms could occur at any
time, so the PROB30 in some TAFs is more of a placeholder and the
details will be fine-tuned by later issuances. Flow should remain
SW on Sunday.
Outlook: A cold front tracks across the western Carolinas late
Monday night before stalling across the forecast area Tuesday into
early Wednesday. This will keep shower and thunderstorm chances
around. Fog and low stratus are expected to develop each morning
across the mtn valleys and anywhere that received appreciable
rainfall the previous day.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JMP
NEAR TERM...AP/PM
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...PM
Area Forecast Discussion
National Weather Service Lincoln IL
753 PM CDT Sat Aug 20 2022
.SYNOPSIS...
Issued at 753 PM CDT Sat Aug 20 2022
Showers and thunderstorms will continue to move through the region
tonight, but should be mainly east of I-57 by midnight. Expect a
few showers to linger in eastern Illinois into Sunday, as a storm
system slowly moves east out of the area. After that, dry weather
will prevail for the first half of the work week.
&&
.UPDATE...
Issued at 753 PM CDT Sat Aug 20 2022
Thunderstorms have lined up more in a west-east configuration
roughly along I-72 this evening, though radar is showing the
outflow pushing south about 15 miles from the main line. Thus, a
general weakening trend should take place as we get into mid
evening. Additional scattered convection south of I-70 is in more
of an untapped air mass, but the severe threat should taper off
some with sunset. Latest HRRR has the convection mainly near or
just north of I-70 by midnight, with the last of the rain out of
the southeast CWA before sunrise. Updates have been sent for the
latest rain trends.
Some concern exists for potential of fog overnight across the
northern CWA as a weak wind shift sets up, especially where
rainfall amounts of 1 to 4 inches occurred earlier. 4 pm run of
the HREF showing 50-70% probabilities of visibilities around a
half mile in the Galesburg-Bloomington corridor, while the
deterministic high-res models showing dense fog potentially as far
south as I-72. Evening satellite imagery showing mainly scattered
clouds to our north within the circulation of the low. Forecast
soundings in this area from the HRRR and NAM do show a slightly
drier layer just above the low-level moisture trapped at the
surface, while the GFS is drier in the overall lower layers. Have
introduced some patchy fog mention for now near and north of I-74,
but will continue to evaluate over the next few hours as to
whether or not to hit this harder.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 250 PM CDT Sat Aug 20 2022
A messy convective environment has evolved north of I-72/Danville
this afternoon with rain-cooled air working to make the near-sfc
environment more stable. Still, there remains appreciable buoyancy
above the cold pool with MUCAPE values exceeding 2000 J/kg. With
additional shortwave impulses rounding the base of the upper-level
low, enough synoptic-scale ascent and instability exists to
maintain thunderstorm development. The most likely hazards for
locations along and north of I-72 as we head into the evening
hours is flash flooding and isolated damaging wind gusts as
updrafts become more pulsey above the strengthening cold pool.
Spotter reports this afternoon have come in with 1-2"/hr rainfall
rates, and this potential should extend downstream as we enter the
evening hours.
Despite parameter space remaining favorable for severe convection
to thrive south of I-72, those locations have lacked an adequate
forcing mechanism. Still, if activity can develop there along and
ahead of the cold front early this evening, severe storms would
become likely. Mesoscale hodographs across our south are
relatively straight, favoring left-moving supercells and a
marginal hail threat.
Having said all of that, the window for severe weather remains
relatively limited as we begin to lose daylight. And with a
weakening LLJ positioned ahead of the cold front, we`re not
anticipating storms to fester deep into the evening.
As the upper-level low begins to open and pivot out the area
overnight, only low-stratus and sprinkles are anticipated Saturday
morning as moisture wraps around the departing frontal system.
Temperatures will be on the cool side Sunday afternoon as cloud
coverage begins to diminish. Afternoon highs should top out near
80 degrees.
.LONG TERM...(Monday through Saturday)
ISSUED AT 250 PM CDT Sat Aug 20 2022
A stretch of dry and seasonably hot weather is expected Monday
through Thursday as upper-level heights maintain a northwesterly
component and expansive surface high pressure encompasses much of
the Midwest and Great Lakes regions. Some potential exists for a
nocturnal MCS to develop Tuesday night as a compact shortwave
trough digs through northwest flow, but any such activity is
currently expected to miss central Illinois to the south and west
as it rides along a surface boundary. Otherwise, thunderstorm
chances return by the end of the week as humidity increases.
Still, activity would likely be isolated thanks in part to dry air
entrainment.
NBM guidance is offering daily highs in the lower 80s Monday and
Tuesday with overnight lows in the low 60s. Conditions then turn
slightly warmer Wednesday through Saturday as surface high
pressure begins to depart and low- level flow veers southerly.
Mid-to- upper 80s will be more common to end the work week with
overnight lows in the mid 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 630 PM CDT Sat Aug 20 2022
Line of thunderstorms will be impacting KBMI-KSPI eastward over
the first couple hours of the TAF period. After that, concerns
shift toward potential IFR conditions late in the night as a wind
shift settles over areas near KPIA/KBMI. Ceilings likely to fall
below 1,000 feet between 09-12Z with some guidance suggesting
sub-500 feet is plausible. Extent of any visibility restrictions
will depend on how much clearing takes place later this evening,
but 1 or 2 mile visibilities will be a concern in the areas that
got a lot of heavy rain earlier today. General improvement in
ceilings should take place late Sunday morning, with VFR
conditions prevailing by 18Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...Geelhart
SHORT TERM...MJA
LONG TERM...MJA
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Louisville KY
731 PM EDT Sat Aug 20 2022
...Updated Aviation Discussion...
.Forecast Update...
Issued at 700 PM EDT Sat Aug 20 2022
Strong convection has mostly pushed northeast out of the CWA this
evening. Still keeping an eye on a small band of storms pushing
northeast of Madison IN. A severe thunderstorm produced quarter-size
hail in a swath through portions of Floyd and Clark counties in
Indiana. Strong winds and a swath of mostly sub-severe hail
continued northeast through Trimble County KY.
The remainder of the evening look largely quiet with dry weather and
clouds continuing to scatter out from west to east. Additional
convection is likely to hold off until at least 08-11z Sunday
morning, when a weakening line will try to push in from the
northwest.
&&
.Short Term...(This evening through Sunday)
Issued at 335 PM EDT Sat Aug 20 2022
Synopsis...Meandering mid-level low over the Midwest will start
moving through the Great Lakes and into the Northeast US during the
next 48 hours and open up as a shortwave trough while several vort
max impulses round the base of the trough and eject ahead of it. At
the surface level, low pressure system will follow suit and
eventually intensify with attendant weak cold front approaching the
forecast area during Sunday night. Although the mesoscale frontal
forcing will be frail, the above scenario will support persistent
mid-to-upper level synoptic forcing through upper jet dynamics,
sufficient effective bulk shear thanks to a +70 kts 250-mb jet core,
and moisture rich southwesterly flow.
Rest of Saturday afternoon...As previously stated in earlier
updates, convection has started to multiply around the forecast area
with the strongest storms at this hour located in the Bowling Green
vicinity. Earlier uninterrupted insolation and high dewpoints have
yield instability values well above 2,500 J/kg and steepening low-
level lapse rates which in conjugation with dry-air in the 700-500
mb layer reinforce the marginal risk of locally severe wind gusts.
On top of that, the expected uptick in the mid-level environmental
wind has caused effective bulk shear values between 25-35 knots this
afternoon; therefore, the preferred storm mode at initiation will be
cellular with some transient supercell structures provided the low-
level SR wind is favorable for further maintenance. Then, a more
linear mode is favored given the inverted V feature shown on the
forecast soundings that advocate for cold pool prevalence.
Marginally severe hail, frequent lightning, and heavy rainfall are
other hazards associated with today`s storms. Regarding location of
highest impacts, SPC has a marginal risk of severe weather roughly
along and north of I-64, but the HRRR SSCRAM model has been
persistent on exhibiting the best severe probabilities along and
east of I-65, in line with current radar imagery.
Saturday Night...Anticipate a downward convective trend after sunset
with most of the storms pushing far away to the east. However, there
is a low chance that a convective outflow ahead of the approaching
cold front could still impact southern Indiana during the first half
of the night. There is some CAM guidance support towards this
output with SCP values between 3-6. Considering a near-surface
stable layer and decreased instability, it will be difficult for any
elevated severe gust to reach the surface. So, small hail and strong
wind gusts are the main impacts for tonight.
Sunday...Best storm intensity and coverage will probably be in the
morning and early afternoon as the left exit region of the upper jet
spreads through central Kentucky, well ahead of the weak cold front.
There will be an instability gradient due to the cloud coverage in
place to the north which will limit diabatic heating. Low-level
winds will slightly increase and turn to the south due to the
passing surface low to the north. This, in turn, will support a low-
end tornado threat during the afternoon when the SCP is also
maximized. Bulk shear values will be once again ranging between 25
to 35 knots, so a mix of multicells and hybrid supercells is
expected
.Long Term...(Sunday night through Saturday)
Issued at 315 PM EDT Sat Aug 20 2022
====================================
Synoptic Overview
====================================
The period will start off with an upper level trough axis crossing
the upper Ohio Valley. This wave, progressive in nature, will
translate eastward into New England by late Monday. Behind the
departing wave, a long wave trough axis will be maintained across
the eastern US with a persistent ridge axis out across the west. The
Ohio Valley will remain in a northwesterly flow aloft with mainly
dry conditions from Tuesday through Thursday night. Some increase
in moisture may occur by late week with the possibility of at least
some isolated-scattered diurnally driven convection by Friday-
Saturday.
====================================
Meteorological Discussion
====================================
Sunday night thorugh Monday night:
Showers and thunderstorms should be in progress at the start of the
period (Sunday night) and will continue into the day on Monday as
the upper trough axis moves east and a cold front finally push
through the region. Best chances of precipitation on Monday will be
mainly across the eastern CWA. Lows Sunday night will be in the mid-
upper 60s with highs on Monday warming into the low-mid 80s. Dry
conditions should be in place by Monday night with lows cooling into
the lower 60s.
Tuesday through Saturday:
With the trough well to our east, a lagging long wave trough axis
will remain in place through much of next week across the eastern US
while the western US remains under ridging. We will have a
relatively quiet period of northwest flow across the region. While
the global models keep things generally quiet, it is possible that
some smaller scale perturbations may drop through during the period
and could produce isolated showers/storms. Given the predictive
scale at days 4-5 here, overall confidence is fairly low at this
point. Temperatures will remain seasonal for late August with highs
in the mid-upper 80s, though some of the urban centers may be a tad
warmer. Overnight lows will generally be in the mid-upper 60s. By
Friday-Saturday daytime highs will generally be in the upper 80s to
near 90 in spots. Some return flow moisture may start to creep
northward in the Friday-Saturday period. This would at least set
the stage for some isolated diurnally driven convection in the
afternoons.
====================================
Weather Hazards/Risks
====================================
Showers and thunderstorms Sunday night and Monday may produce heavy
rainfall, gusty winds and lightning. The progressive nature of the
storms should keep residence times of storms over any location to a
minimum. However, some isolated hydrologic issues in low-lying and
poor drainage areas is possible.
====================================
Forecast Confidence
====================================
Overall forecast confidence with this period with respect to
precipitation is medium. Confidence on temperatures is medium-high.
&&
.Aviation...(00Z TAF Issuance)
Issued at 730 PM EDT Sat Aug 20 2022
A cold front will push into the region tomorrow before stalling over
central KY, accompanied by chances of showers and thunderstorms for
much of the day. Expect potential MVFR CIGs Sunday morning at SDF
and LEX with TS chances increasing by late morning through the
afternoon at all locations. Confidence remains low on exact timing
of storms. Winds will veer from S overnight to SW tomorrow morning.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...EBW
Short Term...ALL
Long Term...MJ
Aviation...CG
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
943 PM EDT Sat Aug 20 2022
.SYNOPSIS...
A stationary front draped across the southeastern U.S. will lift
as a warm front tonight into Sunday. A cold front will then
approach from the Ohio River Valley Sunday into Monday,
attempting to cross the region by the middle of next week. The
front will likely stall nearby or just to the southeast as high
pressure noses in from the Midwest and Great Lakes during the
second half of next week.
&&
.NEAR TERM /TONIGHT/...
A stationary boundary is analyzed across the southeastern U.S.
this evening, extending along the Carolina coast and into the
western Atlantic. Low pressure is situated over the Midwest with
a trough extending into the Ohio Valley. Locally, earlier shower
activity has diminished with the loss of daytime heating. This
evenings upper air sounding out of IAD sampled a fairly moist
boundary layer, with a precipitable water value of 1.65 inches.
Drier air is also evident aloft, which was likely helping keep
the earlier showers in check.
For the remainder of the night, patchy fog is expected to
develop along and west of the Blue Ridge Mountains given ample
low level moisture and light to calm winds. A complex currently
over eastern Ohio and approaching far northwest West Virginia
will push eastward overnight. Hi-res guidance showers this
complex in a weaker form nearing the Allegheny Mountains the
second half of the night, increasing shower and thunderstorm
chances. As such, the gridded forecast highlights increasing
POPs west of the Blue Ridge after midnight and through sunrise
Sunday. Temperatures tonight will settle into the 60s for most,
with lower 70s holding strong near the larger waterways.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A much more active pattern evolves to close out the weekend and
into Monday. The key players feature a northward lifting warm
front currently over the southeastern U.S. and a broad upper
trough trekking across the Ohio Valley. The combination of
these systems will also bolster moisture profiles with
precipitable water values into the 1.50-1.75 inch range. Broad
ascent ahead of this approaching trough will spread shower
activity across the Alleghenies into the I-81 corridor during
the morning hours. Model soundings show ample saturation of the
column, high freezing levels, and tall/skinny CAPE profiles. All
of these are indicators of a heavy rainfall signal. Amongst the
high- resolution models, the 12Z HRRR and FV3 pinpoint a rather
heavy QPF axis from north-central Maryland back into the
eastern West Virginia panhandle. As the 12Z HREF mean does not
contain a large sample size, these models inflate the ensemble
mean at the mentioned locations. Other solutions are not nearly
as robust which casts some doubt on the HRRR and FV3.
A mixture of showers and some thunderstorms are set to press
eastward reaching the I-95 corridor by the late afternoon to
early evening. Instability may be lacking at times given skies
should be fairly cloudy. However, the combination of height
falls and low-level warm/moist advection should offset any limit
in instability. Overall, the main threat does appear to be heavy
rainfall which may lead to some ponding on roads. Any repeat or
training convection could foster a flood issue. Will continue to
monitor the situation during subsequent shifts. In terms of
temperatures, highs top out in the low/mid 80s with another
chance for patchy fog overnight. Much of this will depend on
where rain falls, and how much. Low temperatures remain mild
with readings similar to the previous night.
Rainfall will likely be ongoing into Monday morning as the warm
front to south crosses through the region. This places the Mid-
Atlantic states within a broad warm sector with the upstream
cold front lurking back over the Ohio Valley. There should be a
better shot for thunderstorms given any breaks in the thick
cloud cover. Do expect skies to be rather overcast to start off
the day which may hinder future convective threats. Will
maintain high probabilities for showers through Monday evening
across a vast majority of the region. Some degree of flooding
concerns may loom for areas that get impacted both days. High
temperatures do not budge much from Sunday with another shot for
patchy fog at night.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
A cold front is forecast to pass through the region early on Tuesday
and stall off the eastern seaboard through the end of the week. High
pressure is forecast to build over our region through most of next
week with upper level troughing remaining over eastern Canada and
the NE US. Near average high temperatures in the mid to upper 80s
are likely in the this setup along with light winds. The threat for
hazardous weather will remain relatively low next week as their will
be no noticeable forcing over our region along with little to no
shear. PW`s around 1.5 inches combined with daily CAPE between 1000
and 1500 j/kg will lead to continued chances for isolated afternoon
showers and thunderstorms during the second half of next week.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Low level moisture will remain plentiful overnight, leading to
the potential for MVFR/IFR VIS/CIGs in patchy dense fog into
early Sunday morning. CHO/MRB serve to have the best chance of
such an occurrence. A line of thunderstorms currently pressing
eastward over eastern Ohio may impact MRB toward daybreak Sunday
with a period of sub VFR conditions. Winds will remain light out
of the south southeast into Sunday morning.
Convective threats increase for Sunday and Monday which will
lead to periods of sub-VFR conditions. It is difficult to
discern the thunderstorm threat on Sunday given the degree of
cloud cover. Monday should bring a better shot for thunderstorms
as the region moves into the warm sector. There is also the
potential for patchy fog development during subsequent nights.
Surface winds through Monday are mainly out of the south to
southeasterly. These should turn more southwesterly by Monday
night with the cold front approaching.
Predominately VFR conditions along with light and varying winds are
expected at this time for Tuesday through Thursday.
&&
.MARINE...
Winds remain out of the south to southeasterly through Monday,
generally staying below Small Craft Advisory caliber. Sunday and
Monday are looking more active in terms of convective activity.
Special Marine Warnings will be possible with the taller
updrafts. The threat for convection looks a bit better on Monday
once the Mid-Atlantic region moves into the warm sector.
Sub SCA conditions are likely as high pressure remains over the
region Tuesday through Wednesday.
&&
.TIDES/COASTAL FLOODING...
Tidal levels remain slightly elevated this afternoon. While most
sites have seen their forecasts drop below Action, the exception
will be Annapolis. The next few astronomical high tides will
bring them to the lower side of Action through Monday night.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...BKF/BRO
NEAR TERM...BKF
SHORT TERM...BRO
LONG TERM...JMG
AVIATION...BKF/BRO/JMG
MARINE...BRO/JMG
TIDES/COASTAL FLOODING...BRO
Area Forecast Discussion
National Weather Service Midland/Odessa TX
558 PM CDT Sat Aug 20 2022
...New AVIATION...
.SHORT TERM...
(This afternoon through Sunday night)
Issued at 145 PM CDT Sat Aug 20 2022
...Heavy rain and flash flooding expected this afternoon and
overnight along and north of I-20 south to the Davis Mountains and
Presidio Valley...
A busy afternoon and evening is expected as heavy rain has already
begun to develop across portions of southeast NM. Rich moisture in
place (PWATs >1.5"), sufficient instability, and training cells will
likely lead to efficient rainfall rates on the order 2-3 inches
per hour. This will lead to areas of flash flooding, especially
across SE NM and much of the Permian Basin. Have expanded the
Flood Watch to include these locations and extended it through the
overnight hours.
More rain is possible Sunday, but the greatest concern for flooding
looks to be shifting mainly to our east. A cold front will move into
the region during the afternoon and will be a focus for additional
showers in storms. Temperatures will remain below normal through the
weekend.
&&
.LONG TERM...
(Monday through Friday)
Issued at 145 PM CDT Sat Aug 20 2022
By Mon the cold front and primary mid-level theta-e ridge axis
will be shifting swd taking with it the better chance for rain. As
such Mon into Tue will be sort of a transition from recent high
PoPs toward the lower. Mon AM NBM`s sct-nmrs SHRA/TSRA still ok (a
little too high) for the ern CWFA and then for the PM sct PoPs
favored in the Davis Mtns-Big Bend-Lower Trans Pecos. Still looks
like unseasonably cool temps will be common. There are
indications of a mid-level trof hanging back across W TX into Tue
seemingly supportive for continuation of sct PoPs into Tue,
especially if daytime heating is sufficient to develop SB
instability. Wed there is more of a definitive push of drier mid-
level air, which confine the higher PoPs across the Lower Trans
Pecos, and Big Bend. Warmer temps will accompany the drier mid-
levels, but still below normal. Mid-level ridging does have an
increased presence Thu, especially across the w, while across the
far swrn and srn reaches of CWFA there remains a chance of
SHRA/TSRA. 7h temps signal the continuation of below normal high
temps. Mid-level ridging farther e still expected on Fri, but this
is ahead of a fairly well captured mid-level trof that may
impact/provide some possibility of change Sat-Sun?
&&
.AVIATION...
(00Z TAFS)
Issued at 553 PM CDT Sat Aug 20 2022
Messy TAFs for the next 18 hours or so as an upper trough moves
from NM into the South Plains, bringing convection with it.
Forecast soundings develop IFR cigs over northern terminals
overnight as a weak front settles into the area. Latest HRRR
suggests TAFs will be frontloaded with convection over the next
few hours all terminals. VFR conditions should return Sunday
afternoon as lower cigs scatter out.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 72 90 70 83 / 50 60 60 60
Carlsbad 67 83 66 84 / 60 50 40 40
Dryden 74 93 73 90 / 20 50 50 50
Fort Stockton 70 87 70 85 / 50 60 50 50
Guadalupe Pass 63 76 63 76 / 60 60 40 40
Hobbs 68 85 66 81 / 70 40 40 40
Marfa 62 82 62 81 / 50 70 50 60
Midland Intl Airport 71 89 69 83 / 60 50 50 50
Odessa 73 88 71 83 / 60 50 50 50
Wink 71 88 69 86 / 50 40 40 40
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch through Sunday morning for Andrews-Borden-Chinati
Mountains-Crane-Davis Mountains-Davis Mountains Foothills-
Dawson-Eastern Culberson County-Ector-Gaines-Guadalupe
Mountains Above 7000 Feet-Guadalupe and Delaware Mountains-
Howard-Loving-Marfa Plateau-Martin-Midland-Mitchell-
Presidio Valley-Reeves County Plains-Scurry-Van Horn and
Highway 54 Corridor-Ward-Winkler.
NM...Flood Watch through Sunday morning for Central Lea County-Eddy
County Plains-Guadalupe Mountains of Eddy County-Northern
Lea County-Southern Lea County.
&&
$$
SHORT TERM...99
LONG TERM....99
AVIATION...44
Area Forecast Discussion
National Weather Service Nashville TN
740 PM CDT Sat Aug 20 2022
...New UPDATE...
.UPDATE...
Issued at 734 PM CDT Sat Aug 20 2022
Earlier storms that affected Middle Tennessee have either
dissipated or exited the mid state. So we are left with just a
few light echoes showing up as we head into the night. The HRRR
doesn`t entirely leave us alone the rest of tonight, so we`ll
leave in low POP`s for the duration. The evening sounding from OHX
shows a little more moisture and instability than 24 hours ago,
with a CAPE of 2,784 J/kg and a Lifted Index of -7. PWAT comes in
at 1.65", which is almost at the 75th percentile for this date. So
it looks like we`re primed for even greater coverage tomorrow
with our current air mass.
&&
.SHORT TERM...
(This afternoon through Monday Night)
Issued at 155 PM CDT Sat Aug 20 2022
Upper low centered just west of Chicago this afternoon. one trough
axis extends southward through western TN with a second axis
extending southwest from the low. These two features will serve as
the triggering mechanism for showers and thunderstorms today and
Sunday. We are now looking at a marginal risk for Sunday afternoon
for portions of the northern and central Plateau. The instability
window looks rather brief and extends from 18Z to 00Z or so. Wind
energy, organization and forcing is definitely just on the
marginal side for any severe. That said, cannot rule out some
stronger winds and maybe some pea size hail. Otherwise, precip
amounts not looking too bad through tomorrow afternoon with
average amounts of one half to up to 1 inch for many areas. Some
convection will linger on into Monday across our southern areas as
the associated weak frontal boundary attempts to push through.
For our near term temps, the numbers are looking seasonal with
perhaps a below normal theme in terms of daily max/min ranges, given
the added cloudiness and rainfall.
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 155 PM CDT Sat Aug 20 2022
In the extended forecast, 1000mb-500mb mrh fields definitely dry out
as we move toward mid week. Given the much lower cape to cap ratios
along with more in the way of afternoon subsidence, pops will
basically be out of the forecast for Tuesday and Wednesday. However,
late in the extended, models, especially the Euro, elude toward
redeveloping a weak shortwave over the southeast. Therefore, low
pops will be included by the weekend.
For the extended temps, we will see the upper troughing pattern give
way with some mid level ridging exerting itself by the end of the
week. This is mainly indicated by the gfs with the euro not as
bullish with the warmup. Will include high temps of around 90/lower
90s for now, lows look like the upper 60s to near 70.
&&
.AVIATION...
(00Z TAFS)
Issued at 642 PM CDT Sat Aug 20 2022
VFR conditions are expected at airports this evening before patchy
fog brings MVFR vis to MQY and MVFR/IFR vis to CSV overnight.
Expecting another round of TSRA at airports tomorrow with VCTS and
MVFR conditions possible at all airports. Light south winds
tonight will increase and become southwest 5-10 knots on Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 70 86 68 87 / 30 80 70 20
Clarksville 70 85 67 86 / 30 60 60 10
Crossville 66 78 65 79 / 50 80 70 40
Columbia 70 87 68 86 / 30 70 60 20
Cookeville 67 81 68 82 / 40 80 70 30
Jamestown 66 79 65 79 / 50 80 80 40
Lawrenceburg 69 86 67 84 / 40 70 60 20
Murfreesboro 69 86 67 86 / 40 80 70 20
Waverly 68 84 65 86 / 30 60 60 10
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Rose
SHORT TERM...21
LONG TERM....21
AVIATION.....Shamburger
Area Forecast Discussion
National Weather Service Pendleton OR
826 PM PDT Sat Aug 20 2022
.EVENING UPDATE...Storm activity over the eastern mountains has
ended, with radar showing clearing to our east as the sun sets. Some
storms were briefly strong through the Blues, with small hail and
heavy showers reported with some cells over Wallowa County, but mid-
level instability was lacking and wind shear was virtually non-
existent, so storms developed and died off over very short periods
of time.
Should see a quiet night ahead as the weak upper-level shortwave
that triggered this afternoon`s convection is absorbed by a ridge to
our east and light, stable flow aloft prevails. Not expecting any
new convective activity to develop until an offshore low starts to
move closer to our area late in the day Sunday. 00z HRRR still
showed some decent convective activity across the eastern half of
the forecast area beginning early Monday morning, so fire weather
watch still looks good.
Only made adjustments to sky cover and lows for tonight, as gradual
clearing should take place for any of the forecast area still seeing
some lingering cumulus from the day`s storm activity. Evans/74
&&
AVIATION...06z TAFs...VFR conditions expected through the period.
Skies should remain clear with light, terrain-driven winds. Gusts
in DLS could approach 20-25 kts out of the NW Sunday afternoon,
15-20 kts for BDN/RDM, while the rest of our TAF sites remain
below 10 kts through the day. Evans/74
PREV DISCUSSION... /issued 337 PM PDT Sat Aug 20 2022/
SHORT TERM...Tonight through Monday Night...An upper low over
northern Utah has become disassociated with flow through an
offshore trough over our area. A more west to southwest flow is
developing. This and residual moisture has allowed thunderstorms
to develop over the higher terrain of the eastern Oregon mountains
this afternoon with another couple of cells over the Washington
Cascade crest region. This should continue through sundown then
dissipate. Skies will be mostly clear tonight and this should lead
to temperatures about 5 degrees cooler than last night. Sunday
should a pleasant and generally quiet day with well above normal
temperatures. High temperatures will be in the 90s to around 100
in a few Columbia Basin sites with mainly mid 80s to mid 90s in
the mountains.
The main forecast challenge is about an upper level disturbance
moving through the trough Sunday night and Monday. Am expecting
isolated showers and thunderstorms to move into the southern
portion of the area in the late afternoon. CAM models and the HREF
paintball convection plot show some activity through the night as
it progresses through the eastern two thirds of the area. Monday
morning and afternoon, thunderstorm activity will be greater with
scattered thunderstorms from the Blue Mountains eastward into the
Grande Ronde Valley and Wallowa County. Thunderstorms will move
out of the area in the late afternoon and dry weather is expected
Monday night. Due to the expected lightning, a Fire Weather Watch
for Sunday evening through Monday evening has been issued for the
eastern Oregon mountains and the Columbia Basin zones.
Temperatures Monday will be 3-6 degrees cooler due to the showers
and thunderstorms and the heavier cloud cover. Breezy winds are
expected through the Columbia Gorge Monday afternoon. Perry/83
LONG TERM...Tuesday through Saturday... The extended period is
characterized by the return of dry and calmer conditions accompanied
by another warming trend the latter half of the week as a ridge of
high pressure eventually builds across the western US. Both
deterministic and ensemble guidance are in good agreement regarding
the upper-level pattern Tuesday into the middle of the week with
little variance between model systems. An upper-level closed low
stalls over northeast Washington into the Idaho Panhandle leaving
the CWA under west to northwest flow on the southern periphery of
this feature. While guidance indicates the majority of the CWA
remains dry and precipitation holds to our north and east, lingering
areas of mid-level moisture due to the influence of the low to our
north in combination with daytime heating could support localized
pop-up showers/thunderstorms over a couple select spots around the
region, mainly in the central WA Cascades near Snoqualmie Pass and
in the Wallowa Mtns. Both the ECMWF and GEFS ensemble means seem to
support this solution as well, especially on Tuesday. Subtle, weak
shortwaves swinging around the low may also aid in convective
development however there is note-worthy model to model variance
with these smaller scale features which is to be expected at this
time-range. Given this latter point and considering the signal in
the ensembles, a slight chance for T-storms was added to the
aforementioned locations Tuesday, but not Wednesday due to lower
confidence comparatively; fairly limited impacts nonetheless.
The closed low finally meanders eastward into northern Montana
Wednesday night and Thursday relinquishing its limited influence
over the region. An upper-level ridge of high pressure quickly
follows, building over the Pacific Northwest through the latter half
of the week into the weekend, although model agreement in the
amplitude and placement of the ridge rapidly deteriorates Saturday.
Still, there is at least decent agreement between deterministic and
ensemble guidance in a warm-up through Friday locally even taking
into consideration the ambiguity in the upper-level pattern.
Moderate confidence in the return of triple-digit temperatures to
the lower Columbia Basin Friday, coinciding with above normal
overnight temperatures. The NBM and the ensemble cluster analysis
highlights the breakdown in model agreement come Saturday, with the
former projecting almost a 10 degree temperature spread between the
25th and 75th percentiles for most locations around the region. Most
guidance depicts at least some cooling Saturday afternoon compared
to Friday but it’s within the realm of possibility hot temperatures
persist. 99
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 61 99 64 92 / 0 0 20 20
ALW 64 98 65 92 / 0 0 20 30
PSC 67 99 69 95 / 0 0 20 20
YKM 62 97 66 93 / 0 0 10 10
HRI 60 100 65 96 / 0 0 20 20
ELN 60 94 64 89 / 10 0 10 10
RDM 51 97 53 89 / 0 10 20 0
LGD 58 95 60 88 / 20 0 20 40
GCD 58 98 60 91 / 20 20 20 20
DLS 63 97 67 89 / 0 0 10 10
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Sunday evening through Monday evening
for ORZ641>645.
WA...Fire Weather Watch from Sunday evening through Monday evening
for WAZ691>693.
&&
$$
SHORT TERM...74
LONG TERM....99
AVIATION...74