Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/17/23
Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Sun Jul 16 2023
.DISCUSSION...(This evening through Sunday)
Issued at 129 PM CDT Sun Jul 16 2023
Key Messages:
- Scattered Storms Possible Primarily In Central Wisconsin Late
This Afternoon Into The Evening, Some Strong Storms Possible
- Storm Chances Decrease Tuesday & Increase Wednesday Although
With Decreased Model Agreement
- Seasonable Temperatures To End The Week, Potentially Warmer
Weekend With Slight Precipitation Chances
Tonight and Monday...
Expect some scattered storms late this afternoon into the early
evening as a cold front moves through the area. The best coverage
will be across the northern parts of the area closer to the upper
level low over far southwest Ontario where the forcing will be a bit
better. Decent shear in place on the equatorward side of the low
(30 to 40 knots of effective shear) but not a lot of instability.
The RAP suggests up to 750 J/kg of ML CAPE by late afternoon along
and north of Interstate 94 will quickly dissipate this evening
with the loss of heating. With the shear, this might be enough to
support a strong storm or two at best. High pressure will build in
behind the front overnight into Monday to provide a quiet start
to the work week. The 16.12Z HRRR suggests the thickest wildfire
smoke will get pushed south of the area with the passage of the
cold front although there could be some lingering elevated smoke
Monday.
Tuesday Precipitation Chances:
Similar to the overnight and yesterday`s forecasts, highest
confidence for precipitation and storm chances have pushed southwest
through central into southwestern Iowa. Longer term ensemble
guidance (GEFS 16.1Z; EPS 16.06Z) exhibit low confidence (10-30%)
for greater than a tenth of precipitation late Tuesday Night into
Wednesday from the Desert Southwest-centered 500 mb ridge`s
peripheral vorticity perturbations. With this guidance, and in
collaboration with neighbors, have reduced PoPs for much of
Tuesday.
Midweek Storm Chances:
The farther south solutions result in an increase locally for
storm chances Wednesday. Deterministic models (NAM 16.12Z;GFS
16.12Z;ECMWF 16.00Z) disagree strongly, much more than their
ensemble (GEFS 16.12Z; EPS 16.06Z) counterparts regarding nearly
all aspects of storm possibilities. Severity is highest in the
GFS, exhibiting 2500-3000 J/kg of SBCAPE as well as 15, 30, and 40
kts of 0-1, 0-3, and 0-6km shear, respectively. Timing in the GFS
pushes this plume of instability and line of storms during peak
diurnal heating, into 00Z Thursday. Middle of the pack solution
belongs to the NAM, with a slower solution whilst advecting the
increased low level theta e lobe and attendant instability into
northern Minnesota similar to the GFS. Shear in both the NAM and
ECMWF is strong, 40-45 kts at 0-6 km, outside of lowest 0-1 km
compared to the GFS. GFS suggests low level jet ramping up
Wednesday evening, to not only advect the aforementioned low level
theta e and its attendant instability, but also to much excite
low level shear.
Similar solutions shown in respective models ensemble counterparts,
GEFS dProg/dT wavering 10-20% between runs of moderate to high
confidence (70-90%) for greater than 500 J/kg of SBCAPE in west-
central Wisconsin. While the EPS also wavers by a similar
interval, much lower confidence (10-50%) regarding the same
parameter.
Differing synoptic solutions surround strength of upper level jet
streak, temporarily sustaining the diving and dwindling upper level
low along northwest flow, and accompanying QG advecting the
weakening low farther south and east into the Upper Mississippi
River Valley. As one would expect given previously mentioned
solutions, GFS suggests stronger jet streak with subtropical and
polar dual jet streak transiently conglomerating and therefore
continuing ensemble confidence for lower surface pressure through
central Wisconsin compared to the EPS/ECMWF. Given model
disagreement and potential, something to keep an eye on in coming
forecasts.
End Of The Week:
For the latter half of the week, the upper level low amplifies
downstream over the Great Lakes, and northwest flow resumes as
normal. As we`ve experienced with northwest flow in the last week,
local area susceptible to transient storm chances within this flow.
Currently, nothing of note in long term ensembles as we remain
within the trough. Seasonable temperatures expected into the
weekend before warm air advection later in the weekend into next
week returning precipitation chances.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1000 PM CDT Sun Jul 16 2023
CIGS: SKC/SCT expected through the period.
WX/vsby: no impacts anticipated.
WINDS: northwesterly through the day Monday. Speeds increase by
mid/late morning with a few afternoon gusts around 20 kts. High
pressure builds in Monday with winds lightening up.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...04/JAR
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Denver/Boulder CO
915 PM MDT Sun Jul 16 2023
.UPDATE...
Issued at 915 PM MDT Sun Jul 16 2023
The forecast is performing well with only minor updates this
evening. I have been adjusting forecast temperatures cooler
through the evening, especially around DIA, to meet observations.
Skies are mostly clear to partly cloudy across northeast Colorado
and what clouds we have do not appear to be producing any
precipitation, and are not forecast to.
The 00Z synoptic dataset shows the ridge over the western states
and the upper low nearing the Great Lakes, and Colorado still on
the front side of the ridge with brisk northwesterly flow aloft.
Upstream soundings have a little less precipitable water and GOES
imagery shows very dry air in place for tomorrow. Expect mostly
clear skies and continued warming. Various guidance have trended
cooler a degree or two on high temperatures for tomorrow, mostly
on the eastern plains. Regardless, the urban corridor will still
see the first dangerously hot temperatures of the season, and we
maintain our Heat Advisory for the I-25 Urban Corridor valid
Monday from 10 AM to 8 PM MDT.
The HRRR and RAP Smoke models show a plume of thick smoke from
the fires in Canada circulating just off our northeast corner in
the short term forecast period. Air quality and visibility have
been impacted to various degrees under that plume. The brisk flow
through the ridge looks to protect northeast Colorado for now.
&&
.SHORT TERM...(This evening through Monday)
Issued at 240 PM MDT Sun Jul 16 2023
The main weather concern will be heat in the short term.
There is some high thin cloudiness pushing southeastward across
the forecast area this afternoon. Current temperatures are around
4 degrees warmer over the plains then they were at this time
yesterday.
Models show the upper high and upper ridge now over the southwestern
U.S./Great Basin to push slowly eastward into the Four Corners and
western Colorado by late Monday afternoon. There is no synoptic
scale energy for the CWA tonight or Sunday. The low level pressure
gradient will remain weak as well. Moisture will remain sparse.
There is some CAPE around Monday afternoon, especially over the
eastern half of the CWA, but the CIN never erodes. No pops.
Temperature and thickness fields show Monday`s afternoon highs 3-4 C
warmer than today`s highs. Will leave the Heat Advisory going on
Monday as is.
.LONG TERM...(Monday night through Sunday)
Issued at 139 PM MDT Sun Jul 16 2023
A strong upper level ridge of high pressure stretch from the Desert
Southwest into the Southern Plains States Monday night through
Thursday. Colorado will be under the northern periphery of the high
under the influence of a weak to moderate west-northwesterly flow
aloft. A weak shortwave along with some increase in mid level
moisture may produce isolated to scattered showers and storms,
mainly across the high country. Due to the lack of moisture, most of
the storms will only produce light rainfall and gusty winds.
However, local moisture convergence could result in a couple of
stronger storms with brief heavy rain across portions of the plains.
Temperatures should still be quite hot with max temperatures in the
90s on the plains.
Wednesday through Friday, upper level ridging is expected to amplify
over the Intermountain West. This pattern should allow occasional
upper level disturbances and associated cool fronts to move across
Northeastern Colorado. As a result, this period will see a gradual
cooling trend with a better chance for afternoon and evening showers
and storms, With PW`s between 1.00" and 1.35" some of the storms
could produce locally heavy rainfall. Thursday looks to have the
best potential to see heavy rainfall and possibly some severe
weather across the Front Range Urban Corridor, plains and Palmer
Divide if the cap can be broken.
The models are showing a warming and drying trend over the weekend
as upper level high pressure builds over Colorado and drier air
moves into the forecast area from the north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 609 PM MDT Sun Jul 16 2023
Expect VFR conditions through the period with cloud bases to
remain above 6000 feet. Few to scattered mid and upper level
clouds with no precipitation through this evening. Light easterly
winds are coming around southeasterly this evening on their way to
drainage tonight. A period of light and variable winds is likely
in the early morning, then winds should follow typical diurnal
trends again beneath mostly clear skies, turning northerly to
northeasterly in the afternoon, and around to drainage for the
night.
&&
.FIRE WEATHER...
Issued at 245 PM MDT Sun Jul 16 2023
Humidity values will be in teens for much of the forecast area
Monday afternoon. Wind speeds are not expected to be very strong.
Fire weather conditions will be elevated for the Mountain Parks
Monday afternoon.
Low relative humidity and wind gusts to 30 mph should result in
near Red Flag criteria across South Park Tuesday afternoon.
Conditions are expected to improve by Wednesday due to increased
moisture and shower/thunderstorm activity.
&&
.HYDROLOGY...
Issued at 240 PM MDT Sun Jul 16 2023
Precipitation is not expected tonight and Monday.
A better chance for showers and thunderstorms returns to the
area Wednesday which may bring a flash flooding threat to the
burn areas. Drier conditions are expected to return next weekend.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM to 8 PM MDT Monday for COZ038>040-043.
&&
$$
UPDATE...EJD
SHORT TERM.....RJK
LONG TERM......jk
AVIATION...EJD
FIRE WEATHER...jk
HYDROLOGY......RJK/jk
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
645 PM CDT Sun Jul 16 2023
...New UPDATE, AVIATION...
.UPDATE...
Issued at 645 PM CDT Sun Jul 16 2023
Heat index values have fallen and will likely cancel the Heat
Advisory an hour early. Otherwise, no other changes to the
forecast.
&&
.SHORT TERM...
(Tonight through Monday night)
Issued at 351 PM CDT Sun Jul 16 2023
Adjusted the existing Heat Advisory for all of South Texas
(except for the Islands) by replacing the Advisory over Nueces
and Kleberg counties with an Excessive Heat Warning until 23z,
owing to a significant increase in near surface moisture in
response to the sea breeze (At 1951Z, the CRP 2-meter
temperature/dew point reached 101/80F corresponding to a Heat
Index near 122F.) Extended the Advisory to 01z Monday. No
significant change to the upper synoptic scale pattern over the
region during the period. However, the GFS/NAM deterministic runs
predict lower PWAT values from west to east over the CWA Monday,
and the NAM predicts the LRD/COT moist boundary layer depths at
12z Monday to be slightly lower than the corresponding depths from
the 12z Sunday LAPS. Decided to hoist a Heat Advisory for
mainland South Texas Monday, except for the Webb and LaSalle
counties as downward vertical mixing of drier air will likely
prevent maximum Heat Index values from reaching 110F.
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 351 PM CDT Sun Jul 16 2023
Key Messages:
- Dangerous heat continues next week with heat indices between
110-115 degrees
Not much change from the previous forecast packages. The upper-level
high pressure over the Desert Southwest will increase subsidence
across the region promoting above-normal temperatures. By mid-week
the upper-level high is expected to shift eastward and move into
West Texas. Along with the above-normal temperatures, PWAT values
are expected to be around 1.3-1.4" which will provide enough
moisture to continue promoting dangerous heat index values through
this week. Heat index values are generally expected to range between
105-114 degrees for much of the week except for Tuesday and
Wednesday, where heat index values could rise up to 118 degrees
across the southern Coastal Plains. Please remember to stay
hydrated, limit outdoor strenuous outdoor activity, and look before
you lock your vehicle.
Hazy conditions are also possible at least through midweek as
Saharan Dust streams into the region per NASA/GMAO Dust guidance.
Elevated fire weather conditions will be possible Tuesday and
Wednesday as relative humidity values drop into the 20-40% range
across the Brush Country with winds increasing to the 20-25 mph
range in the afternoon. With 10 hour fuels forecast to range from
the 4-11th percentile across the Brush Country and in the 0-3rd
percentile across the Rio Grande Plains, any fire that develops
could spread rather quickly despite winds being under 25 mph.
&&
.AVIATION...
(00Z TAFS)
Issued at 645 PM CDT Sun Jul 16 2023
HRRR model and HREF probabilities shows less chance for low
clouds/MVFR ceilings to develop during the overnight. Hesitant to
stray from persistence and SREF probabilities that are higher. Low
level moisture profile will be similar to last night. So will go
with MVFR ceilings developing over the coastal plains 04-06Z but
will only go with TEMPO instead of prevailing through 14Z Monday.
Will show patchy fog/MVFR vsbys at ALI/VCT from 10-13Z. Otherwise,
gusty southeast winds this evening becoming south overnight and
morning, then shifting to southeast with the sea breeze Monday
afternoon.
&&
.MARINE...
Issued at 351 PM CDT Sun Jul 16 2023
Weak to moderate onshore flow is expected tonight through Monday
night, except for predominately moderate onshore flow over the
bays and nearshore coastal waters south of Port Aransas this
evening and again Monday afternoon and evening. Moderate
southerly to southeasterly flow is expected for much of the week
with winds increasing to stronger levels Tuesday and Wednesday
afternoon. Therefore, periods of Small Crafts Exercise Caution
and/or Small Craft Advisories could be possible Tuesday and
Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 78 98 78 98 / 0 0 0 0
Victoria 77 101 77 100 / 0 0 0 0
Laredo 77 107 78 107 / 0 0 0 0
Alice 76 103 76 104 / 0 0 0 0
Rockport 81 92 80 93 / 0 0 0 10
Cotulla 77 108 78 109 / 0 0 0 0
Kingsville 77 101 77 102 / 0 0 0 0
Navy Corpus 81 91 80 94 / 0 0 0 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 8 PM CDT this evening for TXZ229>234-239>247-
342>344-346-347.
Heat Advisory from noon to 7 PM CDT Monday for TXZ230>234-
240>247-342>344-346-347.
GM...None.
&&
$$
SHORT TERM...WC
LONG TERM....JCP
AVIATION...TMT/89
Area Forecast Discussion
National Weather Service Glasgow MT
250 PM MDT Sun Jul 16 2023
.DISCUSSION...
AFTERNOON UPDATE:
With visibility improving today to 6 miles or greater in many
locations as the smoke has begun to dissipate, the Dense Smoke
Advisory was allowed to expire. However, haze and less than ideal
air quality is likely to linger through at least Monday morning
looking at boundary layer winds and RAP/HRRR smoke models. A
marginal severe thunderstorm risk remains in the western zones
tomorrow for mainly downburst wind gusts up to 60 mph between
3-8pm. This along with elevated winds near 20 mph behind a cold
front and RH as low as 15% on Tuesday presents some fire weather
concerns for at least the southwest zones. There is high
confidence (90%) in the rest of the week being warmer and drier
than normal as a ridge builds in, though the peak of the heat is
uncertain and trending toward being delayed until early next week.
-Zanker
MORNING DISCUSSION:
Synoptic Setup: Forecast begins with a cool cored airmass centered
over central Manitoba and spread out over the central third of
Canada and a hot, high pressure over the Desert Southwest and
Intermountain West. A weak ridge juts north from the Intermountain
West and runs up into Idaho and southeastern British Columbia.
Northeast Montana lies between the two largest airmasses under
northwest flow.
Today into tonight: Smoke and haze are drifting down in the
northwest flow aloft with higher concentrations lingering along a
frontal boundary from Opheim to Wolf Point to Sidney. Visibilities
at 2AM range from 2 to 5 miles. 03Z RAP model suggest around 10AM
the smoke concentrations will begin to thin across the area as
northeast Montana will be cut off from the source. Prior to that
the inversion will keep current concentrations steady through this
morning till sunrise. After sunrise there may be increase in
concentration and temporary reduction to visibility as well due
to daytime mixing dragging higher concentrations down to the
surface. But eventually the thinning component will win out and
likely around the late afternoon to evening hours. In addition,
the surface boundary is expected to move west slowly through the
afternoon which will take the focal point for highest
concentrations and move it west out of the region as well.
Visibilities should be getting back up to about 6 miles around
roughly Midnight.
Thunderstorms also have an outside chance along the frontal
boundary from mid-morning through mid-afternoon. The ridge/cap
aloft will be acting against this lift. So, if it does occur it
will likely be an isolated shower or thunderstorm and that`s it.
Monday through the evening: Ridge to the west will gain strength
and move eastward exerting more influence and warmth across the
region. Highs should reach into the 90s by Monday and RH will
start to lower down to the point where browning will accelerate
across the southwestern zones. While not yet critical for fire
weather this will require further watching. Meanwhile, a thermal
trough will form under the ridge and allow for afternoon
thunderstorms to form over far western zones and central Montana
Mountains, just west of the ridge axis as it passes. With low RH,
any thunderstorms that do develop will have a greatly increased
chance for high winds with microbursts in the afternoon and
evening hours as they collapse. This is leading to an SPC Marginal
risk across these western zones late in the day.
Monday night through Tuesday: Ridge will peak and exit the region.
The thermal surface trough will set up just ahead of the cold
front and become a focus for thunderstorms into the overnight
hours. Most of these thunderstorms will trail the ridge axis
aloft as it exits east overnight. Then the cold front on its
heels will barrel through Tuesday morning. By Tuesday afternoon
the increased pressure gradient force behind the front should
drive northwest winds, and these numbers could come up to Lake
Wind Advisory levels.
Tuesday night to Wednesday: Expect cool and dry conditions here.
With perhaps a isolated showers or two along the far northeast
International border as the backside of the low tries to wrap
remnant moisture down across the area in northwest flow.
Wednesday night into the weekend: Expect a slow warm up through
this passage of 12 hour periods. Most of which are dry till
Sunday. By Friday 90s for highs may be in store again with
possible 100s rearing their ugly heads around Sunday if the
ensembles do not change. The ridge axis itself looks to transit
across the area Sunday night which may provide a focus for
Thunderstorms on the backside of it as southwest flow approaches.
Confidence in these periods is moderate. GAH
&&
.AVIATION...
UPDATE: 2030Z
FLIGHT CAT: VFR - MVFR
DISCUSSION: Some SMOKE and HAZE continues to be trapped along a
boundary that is semi-stationary over the area. As the smoke plume
is likely to slowly progress to the southwest through tonight,
improvements to VFR visibility have already been seen. However, isolated
and periodic MVFR visibility should remain through Monday
morning. Otherwise there will be scattered high clouds with no
other concerns until isolated THUNDERSTORMS with gusty downburst winds
enter the forecast after 21Z Monday.
WIND: Veering from north to east tonight at 5-10 knots, then
southeast at 10-20 knots Monday.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
633 PM CDT Sun Jul 16 2023
...Aviation Update...
.DISCUSSION...(This evening through Sunday)
Issued at 242 PM CDT Sun Jul 16 2023
Key Messages:
* Slight chance of isolated showers and thunderstorms through
Monday morning. A few of these may end up being strong to
severe, with large hail and strong wind gusts possible.
* Smoke and haze is expected this evening into Monday morning.
* Showers and thunderstorms will again be possible Tuesday
morning, and periodic chances return Wednesday evening through
Saturday.
* Heat index values are expected to reach 100+ degrees across
portions of north central Kansas Monday and Tuesday afternoon.
Currently a broad upper level trough associated with high pressure
over the desert Southwest is positioned across the western CONUS,
while an upper low over the Great Lakes extends a trough south
across much of the eastern CONUS. For south central Nebraska and
north central Kansas, northwestern upper flow prevails with a
shortwave trough moving across the area this evening and tonight.
Forecasting thunderstorms tonight has been tricky as the few
storms initiating this afternoon are not handled well at all,
including by the convective allowing models. Since they are
initiating this early, we can probably expect at least a chance of
thunderstorms this evening and tonight, especially as the
shortwave moves through and with the low-level jet picking up
after dark. Some of these storms may be severe with large hail and
damaging wind gusts being the main threats. The latest CAMs are,
however, now picking up an area of storms moving across the area
overnight and early Monday, potentially impacting the tri- cities
around sunrise and possibly into the morning commute. As far as
the smoke forecast, expecting an increase in smoke tonight into
early Monday morning, diminishing near the surface but likely
still hazy aloft afterward.
Monday and Tuesday...
After the chance of showers and thunderstorms through mid-morning
Monday, the rest of the day should remain dry. As the upper ridge
moves into the Plains, temperatures will ramp up over portions of
the central and southern Plains, with heat indices across north
central Kansas over 100 degrees. The heat will persist over north
central Kansas through Tuesday with heat indices over 100 degrees,
potentially approaching 105 degrees. Overnight Monday night into
Tuesday morning, chances of showers and thunderstorms return to
mainly northern and eastern portions of the forecast area. Some of
these thunderstorms may also be severe, although current model
output indicates the bulk of this activity will be just to our
north and east. Where this area of storms does set up may end up
being a flooding concern as well, with models indicating very
heavy rainfall as this system moves through...again, currently
anticipating this to just miss to the north and east but any
southward trend would put it over our area, so feel it is prudent
to mention.
Wednesday through Sunday... A broad upper trough passing just to
the north mid to late week will bring periodic shower and
thunderstorm chances to the area Wednesday evening through
Saturday. High temperatures will be in the 80s and 90s throughout.
To end the weekend, upper level ridging over the western CONUS
with an upper level trough east puts our area again under
northwesterly flow aloft, indicating another warm day with highs
in the 80s and low 90s.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 626 PM CDT Sun Jul 16 2023
The evening will start off with mostly clear skies, before become
more SCT to BKN with potentially VCTS during the early morning
hours. There is still a lot of uncertainty regarding TS over the
terminals, but feel confident enough to have a period of VCTS in
there. Some high level clouds are expected to persist afterward
any storms move through until the end of the period. Was fairly
confident in putting HZ and/or FU in the TAF, particularly for
KGRI...less so for KEAR, based on the latest RAP smoke model.
Winds will be pretty variable until Monday after sunrise, when
they become northeasterly to eventually easterly.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Hickford
AVIATION...Hickford
Area Forecast Discussion
National Weather Service Grand Rapids MI
1045 PM EDT Sun Jul 16 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1045 PM EDT Sun Jul 16 2023
Mid level shortwave and sfc cold front approaching from WI is
sending a band of scattered to numerous showers and tstms across
Lk MI. Upstream reports from GRB/MKX offices have been mostly
limited to small hail although a few instances of localized wind
damage have occurred.
Air mass in MI is rather dry/stable at this time and would expect
to see a diminishing trend as this convection arrives. That said,
a narrow ridge/ribbon of PWATs near 1.5 and MUCapes near 1000
J/KG is shown by the RAP to poke in ahead of the front overnight.
Latest CAMS are in good agreement showing a fairly solid line of
showers/isolated tstms extending from HTL to MKG at 05Z (1 AM),
weakening by the time it reaches a LAN to AZO line around 08Z
(4 AM).
Severe weather is not expected overnight with these storms
although gusty winds up to 40 mph and small hail are possible
over Lk MI and along the shoreline north of Holland over the next
few hours before the line begins to dissipate.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 242 PM EDT Sun Jul 16 2023
- Smoke decreasing early tonight then returning overnight -
The Canadian National Wildfire Smoke Model indicates that much of
southwest Lower Michigan will see decreased smoke concentrations
this afternoon into early evening, especially near and north of I-96.
The respite will be brief because another surge of smoke is
expected, starting around midnight ahead of a cold front dropping
south through the area.
- Showers overnight, maybe a Lake Michigan storm -
Model guidance indicates lingering surface based conditional
instability over Lake Michigan tonight that will be marginally ample
to support thunderstorms ahead of the approaching cold front. Would
not rule out a special marine warning or two, especially given the
strong expected winds in the cloud bearing layer. Any thunderstorms
that develop would most likely weaken upon moving onshore. We do
have thunderstorms in the forecast over land as well, but these will
be low probability and could possibly be removed based on trends
early tonight.
Precipitation amounts will be light, most likely remaining well
below a tenth of an inch. It`s possible some areas around US-127
will receive no rain at all.
- Smoke early Monday, likely exiting southeast during the day -
Although the current air quality alert is for the whole day Monday,
model guidance does suggest conditions could improve significantly
by afternoon. For the latest information please refer to the
Michigan Department of Environment, Great Lakes, and Energy page on
the internet at... http://www.michigan.gov/EGLE.
.LONG TERM...(Tuesday through Sunday)
Issued at 242 PM EDT Sun Jul 16 2023
- Next Chance for Precipitation Midweek
Another solid looking upper level jet and mid level low is forecast
to move into the upper Great Lakes by midweek. At the low levels, a
cold front will likely sweep through Michigan Thursday. Frontal
timing will be key to our risk for thunderstorms. Ahead of the
front, models are showing deep layer shear of 40-50 kts with a mid
level jet around 50 kts. PWATs look to be around 1.25" with dew
points likely in the mid to perhaps upper 60s. While not overly
impressive, this moisture may be enough to help fire convection
provided surface based instability develops given we will have
synoptic forcing in place. If the front moves through early
Thursday, then our risk for thunderstorms would be minimal. Should
the front hold off until late Thursday, thunderstorms with strong
wind gusts and hail could conceivably occur, especially away from
the lakeshore region.
- A Few Showers Possible Friday into Saturday
As the upper wave slowly exits the region Friday, there may be
enough low level moisture remaining in the midst of cold air
advection to help generate a few showers or a thunderstorm over the
region, mainly Friday but the ECMWF does favor a chance lingering
into early Saturday as well. Since there is a divergence in model
guidance regarding the speed at which the upper wave exits,
uncertainty exists in when we begin drying out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 754 PM EDT Sun Jul 16 2023
Band of scattered showers and tstms moving east from WI should
reach MKG around 03Z then weaken/diminish while continuing east
through the area overnight. Will only carry a thunder risk at
MKG, and this may be accompanied by a brief period of gustier
winds and a wind shift.
It`s possible that GRR will see a gusty thundershower as well
around Midnight, but then mainly just a brief shower risk will
exist the terminals south and east of GRR as the convection
continues to weaken.
Otherwise VFR weather is expected to prevail tonight and Monday,
but can`t rule out a period of MVFR vsbys in smoke late tonight
into early Monday. West winds will pick up by 15Z Monday, gusting
up to 25 kts at times before relaxing later in the day.
&&
.MARINE...
Issued at 242 PM EDT Sun Jul 16 2023
Winds and waves are expected to remain below advisory thresholds.
However, locally higher winds associated with showers and even
possible thunderstorms can be expected tonight (mainly before
midnight) prior to the passage of a cold front. Winds behind this
front are not expected to be strong enough to build waves to small
craft advisory levels, however. Visibility restrictions in smoke and
haze will persist well into Monday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Meade
SHORT TERM...TJT
LONG TERM...Hoving
AVIATION...Meade
MARINE...TJT
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1020 PM EDT Sun Jul 16 2023
.SYNOPSIS...
Weak high pressure will bring mostly dry conditions to the
region this evening. A cold front will push southeast through
the Great Lakes and Ohio Valley tonight into Monday, bringing a
chance of showers and thunderstorms. Precipitation chances will
decrease Monday night as the front slows down near the Ohio
River.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Mean mid level trof from south central Canada thru the eastern
CONUS settles a little south into the Great Lakes. Showers and
thunderstorms developed late in the day in a region of low level
theta-e advection to our west across portions of central Indiana.
This convection has tracked into ILN/s FA this evening with a
general weakening trend as the storms moved into a less favorable
environment over ILN/s area.
A few of the storms could contain gusty winds or small hail but
mid level lapse rates are marginal, so hail is becoming less
likely. With the loss of daytime heating and with weak
background forcing -- expect a continued general weakening/diminishing
trend. As we head into the overnight hours the more favored
region to support a shower or storm shifts south into the Tri-
state region.
Smoke/haze was generally restricting vsbys to 3 to 6 miles.
Have kept a mention of haze/smoke through the night but there
are indications that there may be some improvement in
widespread haze conditions with a transition to a patchy fog
scenario. Also, an increase in clouds will likely inhibit the
development of widespread dense fog.
Lows expected to range from the mid to the upper 60s.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As the initial decaying system lingering from the overnight
period would yield spotty showers and a possible rumble of
thunder early, a stronger shortwave will push through the area,
steered by the mid/upper level northwest flow. The approach of
an associated cold front, overall coverage of storms will bring
a greater coverage of convective activity during the afternoon
hours.
While the region is largely no longer under the Marginal risk
for Monday afternoon, there remains enough 0-6km shear and
instability to keep a mention of a few strong storms possible,
and a severe storm or 2 can`t be ruled out.
Overall confidence in persistence of haze/smoke decreases with
the greater coverage of showers and possible thunderstorms
during the day on Monday. The potential for storm outflow winds
and greater coverage of showers, along with some hints from the
12z HRRR vertically integrated smoke show a potential visibility
clearing through the afternoon and a retreat of the smoky
conditions further to the north.
Highs on Monday will range from the upper 70s to mid 80s.
For Monday night, confidence is growing in an overall slowdown
of the frontal boundary, where it will linger near the Ohio
River. As a result, scattered to isolated showers with spotty
thunderstorms will remain possible generally south of I-70.
Overnight lows in the 60s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
On Tuesday, a large upper trough will be centered over northern
Ontario, moving east into northern Quebec. A general pattern of
troughing will remain in place across the Great Lakes and Ohio
Valley, though behind a cold front coming through Tuesday morning,
the boundary layer will be a little drier. With the front still
likely to be near the southern sections of the ILN CWA as it stalls
out and orients roughly west-to-east, some showers and storms may be
possible on Tuesday. However, chances will be kept rather low, and
only in the southern part of the area.
Chances for precipitation are expected to increase by late Tuesday
night into Wednesday. The Ohio Valley will remain on the southern
periphery of a longwave flow pattern with troughing over the
northeastern states, and generally northwesterly flow over the
region -- eventually turning more zonal toward the end of the week.
With increasing theta-e into the middle Mississippi valley region,
and a weak 500mb wave moving across the frontal boundary from west
to east, this is a pattern that will support convective development.
This development may, however, be most focused just southwest of the
ILN forecast area. The chances for getting some rain and storms into
the area appear fairly high, but the potential for severe weather or
heavy rain is less clear. PoPs will be kept in the likely category
(focused on Wednesday morning) with low confidence in the specifics
for this part of the forecast.
With the frontal boundary moving north of the area on Thursday,
additional showers and storms are expected, perhaps across much of
the area. This will continue into Thursday night, before a cold
front is expected to move through the region. Behind the front,
slightly cooler and drier conditions are expected, with rain much
less likely for Friday and Saturday.
Temperatures through the extended period will be near normal to
slightly below normal for the most part. This means highs generally
in the lower to mid 80s and lows in the mid to upper 60s. Thursday
may be the warmest day of the period, as the warm front will be
north of the area, with temperatures in the mid to upper 80s (and
dewpoints in the 70s).
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Mean mid level trof from south central Canada thru the eastern
CONUS settles a little south into the Great Lakes. Showers and
thunderstorms developed late in the day in a region of low level
theta-e advection across portions of central Indiana and have
tracked into west central Ohio. Marginal to moderate instability
exists in the genesis region for these storms. A few of the
storms could contain gusty winds or small hail but mid level
lapse rates are marginal. With the loss of daytime heating and
with weak background forcing -- expect a general weakening/diminishing
trend as we head into the late evening. A few dissipating storms
or showers may affect the TAF sites prior to diminishing. As we
head into the late evening the more favored region to support a
shower or storm shifts south into the Tri-state region.
Smoke/haze was generally restricting vsbys to MVFR. Have kept
MVFR haze/smoke through the night but there are indications that
some improvement in widespread haze transitions to patchy fog
scenario. Mid level clouds which move into the area should
inhibit the development of widespread dense fog overnight.
Moderate instability develops ahead of an embedded shortwave
Monday. Expected scattered thunderstorms to develop Monday
after 19Z but with low confidence on exact timing for any TAF
sites have limited mention to VCTS at this time.
Southwest winds decrease this evening to around 5kts and then
around 10 kts Monday afternoon.
OUTLOOK...Thunderstorms possible at times Tuesday night into
Thursday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JDR
NEAR TERM...AR
SHORT TERM...JDR
LONG TERM...Hatzos
AVIATION...AR
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
907 PM CDT Sun Jul 16 2023
.SYNOPSIS...
Issued at 907 PM CDT Sun Jul 16 2023
Scattered thunderstorms are expected late tonight into Monday
along a cold front moving into central Illinois from the
northwest. Smoke will become less of a nuisance Monday evening in
the wake of the frontal passage. Attention then shifts toward
Tuesday with the potential for heavy rainfall and localized
flooding. Drier conditions return to the region later in the week
and will extend through next weekend.
&&
.UPDATE...
Issued at 907 PM CDT Sun Jul 16 2023
Updates this evening have been made for reduced evening precip
chances with an initial disturbance now well east of the forecast
area, and no shower activity at present. Nevertheless, a couple of
additional features tonight could bring more showers and
thunderstorms overnight. First, CAMs are developing convection
from central MO into west-central IL in the next couple of hours
as enough low level jet increase helps to trigger some convection
in this area. This could affect areas mainly from Jacksonville to
Effingham southward. Meanwhile, the cold front approaching from
the north should bring some scattered convection spreading
southward into the area after midnight, possibly fairly minimal
until a more pronounced shortwave arrives late in the night to
enhance lift. Thunderstorms should not be severe through morning
with relatively tame instability values under 1000 J/kg. Morning
lows in the mid 60s still look on track.
37
&&
.DISCUSSION...
Issued at 225 PM CDT Sun Jul 16 2023
Key Messages:
* Periods of scattered thunderstorms now through Monday
afternoon;
* Wildfire smoke eases Monday night, if only temporarily;
* Heavy rainfall becoming more likely Tuesday and Tuesday night;
* Stretch of drier weather arrives midweek.
Scattered T-Storms:
Current satellite and radar trends capture ongoing convection
across central Missouri, extending eastward into the St. Louis
metro area along an outflow boundary. This thunderstorm activity
has pushed a thickening anvil into central Illinois, which may
ultimately work to limit thunderstorm coverage across our CWA.
Nevertheless, CAMs remain consistent with at least isolated
convection developing between 21z-01z/4pm-8pm over central
Illinois. Such activity would be forced by an incoming mid-level
shortwave impulse, moving ahead of and parallel to a weak cold
front positioned to our north. CAPE/Shear profiles support
marginally severe storms, with recent RAP mesoanalysis data
depicting 2000+ J/kg of MLCAPE and effective-layer shear between
25-35 kts. Even with the favorable parameter space positioned over
central Illinois, upstream storms appear to be developing along
and south of the anvil gradient. This perhaps favors locations
along and south of a Springfield to Paris line for severe weather
over the next few hours.
Additional convective chances (30-50%) exist late this evening
and into Monday as the cold front slowly sags into central
Illinois. The severe weather threat is expected to wane overnight
with the gradual loss of buoyancy, but an increasingly favorable
environment develops tomorrow afternoon ahead of the front.
Boundary layer conditions will be characterized by low 70s sfc
dewpoints and MLCAPE values > 2500 J/kg. This, in tandem with
increasing mid- level flow, supports supercell structures as deep-
layer shear increases to 40 kts. Locations south of I-72/Danville
will be in line for severe storms Monday afternoon, with a
special emphasis across our southeastern CWA where very large hail
and damaging winds could develop.
Smoke:
Latest forecast guidance from the HRRR/RAP hint that the higher
concentrations of near-surface smoke will get flushed away Monday
night as a cold front pushes south of our area. This will mark a
return to better air quality across the region, and we have
therefore not extended the Air Quality Alert beyond tonight
despite a narrow ribbon of smoke lingering into Monday along the
front. We`ll continue to watch late this week for additional smoke
that might filter into the region, especially as northwest mid-
level flow becomes more prevalent.
Heavy Rainfall Potential:
Global deterministic guidance continues to trend a little further
south with the axis of heaviest QPF on Tuesday and Tuesday
evening. Locations along and south of a Beardstown to Springfield
to Robinson line have the highest probability of exceeding 1" of
rainfall.
From a synoptic viewpoint, the Tuesday setup loosely resembles a
Maddox model for flash flooding. While instability looks limited,
the skinny CAPE and deep warm cloud layer should help support
efficient rainfall rates, especially with PWAT values exceeding
90th percentile values for this time of year. Given the abundant moist-
ascent along and atop the surface front, it`s not unreasonable to
hedge on the higher end of NBM QPF percentiles, with the 90th
percentile offering upwards of 2.25" between Tuesday and
Wednesday. This may threaten at least some degree of flooding,
with our 3-hour flash flood guidance able to handle 2-3" in such
time span.
Drier Conditions:
Beyond Wednesday, a stretch of much drier weather is anticipated
through the weekend as an elongated area of surface high pressure
builds into the Midwest along the eastern periphery of an upper-
level ridge. Temperatures and dewpoints don`t look overly
supportive of isolated, summertime pop-up storms from Wednesday
through Saturday, but we wouldn`t completely rule it out.
MJA
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 649 PM CDT Sun Jul 16 2023
Thunderstorm activity over the central IL terminals looks likely
to hold off until after 05Z, at which point widely scattered
showers and thunderstorms should be possible until around 18Z.
Smoke will linger across the area over much of the upcoming 24
hours, although some dissipation of the smoke is possible later
this evening with some cleaner southwest flow ahead of an
approaching cold front. A more pronounced clearing looks on track
for after 00Z as a cleaner northerly flow arrives. Until then,
periods of MVFR vsby are possible. Winds W-SW 5-10 kts through
tonight, becoming NW around 10 kts by 18Z.
37
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Indianapolis IN
1058 PM EDT Sun Jul 16 2023
...Updated Aviation Discussion...
.Forecast Update...
Issued at 936 PM EDT Sun Jul 16 2023
Modest low level 30 knot jet, moving into southern Illinois, along
with a weakening yet unstable atmosphere and impulses around the
northern Ontario supports more convection overnight and especially
over southwestern sections. Sufficient bulk shear but weakening
instability suggests storms will stay below severe limits. PWATs to
1.5 inches or less suggests flooding threat will be low although the
area will be in the RR quad of 95kt Lake Erie jet streak which
supports some enhanced rainfall.
Cloud cover and current dew points support overnight lows in the mid
60s.
&&
.Short Term...(This evening through Monday)
Issued at 301 PM EDT Sun Jul 16 2023
The primary synoptic-scale feature in the short term period is a
broad deep closed low moving slowly east-southeastward across
Ontario. Trajectories will allow for Canadian wildfire smoke to
continue advecting into central Indiana. Satellite imagery already
shows a thick plume of smoke across the region with most areas
seeing reduced visibilities around 4-7 miles. This is expected to
continue through the day. Reference the latest Air Quality Alert
Message (AQAIND) for the latest messaging relayed on behalf of the
Indiana Department of Environmental Management.
A few subtle upper level impulses rotating around the aforementioned
deep closed low will likely bring multiple rounds of convection
through the period. The first round of convection should arrive this
evening. CAMs are in good agreement that a strong complex of storms
currently over Missouri will sustain itself and move east towards
central Indiana. Increasing low-level theta-e advection will promote
moderate destabilization by this evening. This along with near 30
kts of effective shear and steep low-level lapse rates may support
organized convection with isolated damaging wind gusts. Marginal
severe hail cannot be ruled out either. These storms will likely
push the higher concentrated smoke and haze east during the evening
and overnight, but minor visibility reductions and haze are expected
to linger through Monday. Additional showers and storms will be
possible through the night as a strengthening nocturnal LLJ helps
advect warm-moist air into the area. In addition, a shortwave trough
will be moving through which should increase convective coverage.
The best forcing overnight will be confined to far southwest
portions of central Indiana. Forcing is weak further north and east,
leading to lower confidence in rain chances tonight.
Latest CAMs are in better agreement regarding thunderstorm potential
for Monday. Isolated showers and storms may be ongoing to start the
day, but the better chance for precipitation should be late in the
day. Most CAMs show numerous thunderstorms developing ahead of a
cold front during the afternoon and evening. Guidance suggest
daytime heating of the warm-moist PBL across central IN will support
moderate destabilization. MLCAPE around 2000 J/KG and Effective bulk
shear near 35 kts could support a few strong to severe storms.
Isolated damaging wind gusts, large hail, and localized flooding
would be the primary hazards. It is worth noting some uncertainty
still exists regarding how much the atmosphere can destabilize by
the afternoon due to cloud cover or any potential convection early
in the day.
Convection should begin to dissipate towards sunset as instability
weakens. However, models show the cold front stalling near southern
portions of the area. This may allow for a few additional storms to
fire up overnight within a modest LLJ. Further north, subsidence
behind the front should allow for quiet weather conditions.
&&
.Long Term...(Monday night through Sunday)
Issued at 301 PM EDT Sun Jul 16 2023
The first half of Tuesday looks to be rather quiet with weak high
pressure in place. A shortwave trough will begin to approach later
in the day with increasing chances for thunderstorms. Models are
strongly signaling at an MCS associated with the trough to develop
across the northern plains and propagate towards the region. There
is a strong signal for an MCS to develop, but models are not in good
agreement regarding the exact location of initiation and propagation.
Some guidance have the MCS impacting southwest portions of central
Indiana while others keeping it further south and west.
If an MCS were to impact portions of the area, both flash flooding
and severe weather would be possible sometime late Tuesday through
early Wednesday morning. Forecast soundings show the potential for
efficient rain producing storms with a warm cloud layer depth over
13K ft, nearly moist adiabatic lapse rates throughout the column,
and above normal PWATs exceeding 2 inches. This could quickly lead
to flash flooding, especially if areas see repeated rounds of
convection. In addition, guidance generally shows moderate
instability and strong deep-layer shear across far southwest-central
IN supporting the potential for severe weather. Damaging wind gusts
would be the primary threat, but model soundings show sufficient
LLWS for quick spin-ups. High PWATs and moist-adiabatic profiles may
limit the large hail threat. In conclusion, there is a threat for
flash flooding/severe weather late Tuesday into early Wednesday
morning, but models are struggling determine where the MCS will
initiate. Model ambiguity in regards to the potential MCS leads
to uncertainty in this scenario occurring. Trends in guidance
will continue to be monitored closely.
The active pattern looks to continue through Thursday as a few more
upper waves likely move through. The best chance for rain will be
during the afternoon/evening as the PBL destabilizes. Relatively
quiet conditions should return towards the end of the week as a
drier airmass advects into the region.
&&
.Aviation...(00Z TAF Issuance)
Issued at 1058 PM EDT Sun Jul 16 2023
Impacts:
- Brief MVFR and worse conditions possible in convection
- Wind gusts to 50 knots possible in severe thunderstorms this
evening
- MVFR haze possible from the western Canadian wildfires
Discussion:
Several rounds of thunderstorms will move over the terminals this
evening and Monday with the best chances this evening and Monday
afternoon. A few could be strong or marginally severe with gusts to
50 knots. In addition, smoke from the western Canadian wildfires
will restrict the visibility to MVFR.
Winds will start off WNW, shift to the SW late tonight and back to
WNW Monday afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...Melo
Long Term...Melo
Aviation...MK
Area Forecast Discussion
National Weather Service North Platte NE
639 PM CDT Sun Jul 16 2023
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 315 PM CDT Sun Jul 16 2023
Key Messages:
- Smoke will linger across portions of northern NE today, shifting
southwestward Monday
- Isolated thunderstorms this evening, more widespread severe
weather possible Monday evening into Tuesday morning
- Active weather continues through the workweek with several
chances for thunderstorm development
- A warming and a drying trend begins late next weekend
&&
.SHORT TERM...(This evening through Monday night)
Issued at 315 PM CDT Sun Jul 16 2023
Some smoke from Canadian wildfires remains across the area this
afternoon. Though primarily aloft, there are reduced visibilities
north of highway 2 suggesting air quality may be impacted some
there.
A very subtle mid level short wave was sliding southeastward from
MT/wrn SD early this afternoon, as seen in water vapor imagery and
also very subtle upper divergence noted in subjective analysis of UA
data this morning. This is notable in the wake of morning convection
as low level lapse rates have responded well across the northwest
part of the area into western SD early this afternoon, which will
help to establish an area of modest ML CAPE late this afternoon, in
the presence of good deep layer shear. With the main ribbon of
higher upper level wind across eastern Dakotas, the associated cold
front will sag southward and may interact with the Black Hills lee
side convergence zone, resulting from the decent northwest flow, to
develop isolated storms along it. 12Z CAMs all seem to show some
idea of this, with the notable exception of the HRRR (starting to
show shallow convection as of the 16Z run). Confidence in a concise
area of convergence sufficient to develop thunderstorms is low so
precip chances are isolated at best.
If storms develop, they should dissipate after sunset late this
evening as the area settles under light easterly flow at the surface
as high pressure moves into northeast NE late tonight. In addition,
a northerly flow just off the surface will not be conducive for
further storm development overnight. Low level moisture remains good
and with the easterly flow would expect to see the persistent smoke
push south and then westward overnight. With the extra particulates
in the air, it wouldn`t be out of the question to see a visibilities
reduced in fog, especially in river valleys. With only medium
confidence in this have not added to the forecast as fog, though the
smoke will be mentioned.
For Monday, the bulk of the day should be dry and mainly sunny, with
the caveat of smoke remaining through the day. The upper ridge axis
shifts eastward while breaking down somewhat, though upper
heights will be rising through the day and creating broad
subsidence aloft across the northern Plains. By afternoon, with
the surface high pressure retreating, southerly return flow will
set up across the western Sandhills and much of the High Plains.
This will bring a return of better low level moisture and with
good insolation during the day, will yield an unstable environment
across the area, with ML CAPE values nearing 2500 J/Kg. Meanwhile
a more potent upper level PV anomaly will progress eastward near
the WA/Canada border. Ahead of this feature, a separate but fairly
stout upper PV anomaly will move quickly into MT/WY as the
resultant quick zonal flow aloft induces strong pressure falls in
the northern High Plains. Southerly flow will strengthen in
response to these lowering pressures setting up a strong nocturnal
LLJ from the central High Plains into the Dakotas. All of this
sets the stage for good confidence in the development of a
convective complex from Monday evening into the morning hours of
Tuesday. A broad slight risk of severe storms is already in place
for this from central SD into northern NE. However, the timing of
the beginning of this impending convective complex is a bit in
question as some CAMs suggest an early evening Monday start to the
convection, while some focus the best lift along the elevated
warm front that lift north as a result of the LLJ development,
after midnight. Details will be refined on this timing issue, but
there is good confidence in a complex of Storm to severe storms
in some fashion Monday night. Good deep layer flow aloft will
promote long hodographs and the potential for large hail in the
initial stages of the development, with a possible transition to
damaging wind depending on how strong of an inversion there is
ahead of the convection after sunset.
.LONG TERM...(Tuesday through Sunday)
Issued at 315 PM CDT Sun Jul 16 2023
An anomalous upper low will begin to organize in the Gulf of Alaska
by midweek which will allow a poleward expansion of the upper ridge
across the west. This ridge will expand to cover much of the western
two-thirds of the CONUS by late next weekend leading to a warming
and drying trend late next Saturday toward the first of next week.
However, in the meantime a continued active weather pattern will
remain across the Plains. Temperatures will remain close to average
Monday and Tuesday, but will be below average through Friday before
warming once again.
Strong to severe storms will likely be ongoing for the eastern
portions of the area Tuesday morning. In their wake, a brief lull,
but a secondary cold front will slide southward again by evening
This may become a focus for additional thunderstorm development by
late afternoon across the northwest, but much will depend on the
expanse of subsidence provided by the exiting convective complex. As
the anomalous upper low slides eastward along the Canadian border,
the continued fast flow aloft, which transitions from zonal back to
northwesterly by the end of the week, will provide the necessary
shear for organized convective development each day through
Friday. Although briefly disrupted by the daily convection, low
level moisture will remain plentiful as well through the week. The
GFS deterministic solution does scour out the low level moisture
Friday into Saturday, but with the continued precipitation across
the area and resultant soil moisture fluxes in periods of good
sunshine, believe this is too aggressive and favor the slightly
more humid ECMWF and associated implied ensemble probabilities.
With the ridge building more into the Plains Saturday through
Sunday, the warming trend will ensue and a drier forecast is in
place.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM CDT Sun Jul 16 2023
Haze/smoke will continue to hang around north central Nebraska
into the northern Sandhills this evening into tomorrow. Tomorrow
morning the haze/smoke may move southward into portions of the
southern Sandhills, including KLBF terminal. Winds will be light
and variable overnight, then out of the southeast around 5 to 10
kts in the afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Stoppkotte
SHORT TERM...Stoppkotte
LONG TERM...Stoppkotte
AVIATION...Gomez
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
613 PM PDT Sun Jul 16 2023
Updated Aviation Section
.SYNOPSIS...16/117 PM.
Dangerously hot temperatures are expected across the interior
through at least Monday as strong high pressure remains over the
West Coast. Onshore flow and a shallow marine layer will keep
areas near the coast much cooler, but still above normal. A
slight cooling trend is expected through the middle of the week,
however warmer temperatures are expected for the latter half of
the week as the high pressure ridge returns.
&&
.SHORT TERM (TDY-WED)...16/147 PM.
Another extremely hot day across the Antelope Valley where
temperatures again are expected to top out at or above 110
degrees. Also very hot across the remainder of the interior,
including the mountains and interior SLO County where highs
between 100 and 108 are expected. Also impressive were the
overnight temperatures which in some areas (especially the
mountains) didn`t drop below 85. A 2mb onshore push today is
starting to work its way into the valleys and temperatures there
today have generally been trending a degree or two cooler.
Going forward through the middle of the week increasing onshore
flow along with weakening high pressure aloft is expected to bring
temperatures down away from the coast but still remaining above
normal. Overnight lows will be cooling some as well but still
expecting temperatures staying above 75 in many elevated areas.
Current heat advisories and warnings still go through Monday.
Though some consideration has been given to extending those
another day, based on the latest forecast afternoon and overnight
temperatures are expected to drop enough to keep them out of the
warning and advisory criteria after Monday.
Coastal areas will continue to deal with low clouds and
areas of dense fog, some of which may linger through the
afternoon. Temperatures there will remain slightly above normal
but much cooler than the interior.
Still monitoring the potential for convection as moisture moves
into the area from the south through Monday. While there is some
instability, the bulk of the moisture continues to stay at levels
that are typically too high for thunderstorm development locally.
Thus, chances (generally 10 percent or less) remains too small to
include in the forecast but some isolated cumulus development is
expected neat the peaks in the afternoon, and a fair amount of
ACCAS is likely overnight into the morning hours from storms that
form over Mexico. Latest HRRR does indicate some light precip
beyond the 60nm boundary of the coastal waters later tonight into
Monday morning so will need to keep a close eye on convection to
our south for potential storms moving into our coastal waters.
.LONG TERM (THU-SUN)...16/149 PM.
Most of the ensemble solutions continue to favor a trend towards
warmer temperatures for the latter half of the week into early
next week as high pressure builds back west again. However, at
this time the ensemble based guidance only shows about 10% chance
of temperatures reaching 110 or higher across the interior and
just under 50% for temperatures of 105 or higher across the
coastal valleys. So definitely continued above normal but likely
not quite as warm as the current heat wave. Onshore flow does
weaken later in the week but remains pretty healthy so this again
appears to mainly impact inland locations with much cooler temps
at the coast with a continued strong marine layer influence.
&&
.AVIATION...17/0110Z.
At 01Z over KLAX, the marine layer was 800 feet deep. The top of
the inversion was at 2500 feet and 31 degrees Celsius.
Moderate confidence in presence and flight cats of ceilings and
visibility, low confidence on timing (plus or minus 6 hours).There
is a 5 percent chance of -TS at most coastal sites 06-18Z.
KLAX...Low confidence on when ceilings will surge over entire
airport, likely window of occurring 01-04Z. Moderate confidence in
ceilings 003-006, with a 10 percent chance of VLIFR dense fog
10-14Z. No significant easterly wind component is expected. 5
percent chance of -TS 06-14Z.
KBUR...High confidence in VFR through 00Z with minimal issues.
&&
.MARINE...16/109 PM.
No changes to the marine forecast in the afternoon issuance.
For the Outer Waters, moderate to high confidence in current
forecast. Today through Tuesday morning, high confidence in winds
and seas remaining below Small Craft Advisory (SCA) levels. On
Tuesday afternoon and night, there is a 50-60% chance of winds
increasing to SCA levels and remaining at SCA levels Wednesday and
Thursday, in the far northwest corner.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Monday, high
confidence in winds and seas remaining below SCA levels. For
Tuesday, there is a 30% chance of SCA level winds in the afternoon
and evening hours. For Wednesday and Thursday, there is a 50-60%
chance of SCA level winds in the afternoon and evening hours.
For the Inner Waters south of Point Conception, high confidence in
current forecast. Today through Thursday, high confidence in winds
and seas remaining below SCA levels.
A shallow marine layer depth across the coastal waters will
continue to bring dense fog with visibility one nautical mile or
less, especially during the late night and morning hours.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning in effect until 11 PM PDT Monday for
zones 38-88-343>345-352-353-376>383. (See LAXNPWLOX).
Heat Advisory in effect until 11 PM PDT Monday for zones
348-356>358-367-369>375-548. (See LAXNPWLOX).
PZ...NONE.
&&
$$
PUBLIC...MW
AVIATION...RK
MARINE...Sweet/RAT
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
Area Forecast Discussion
National Weather Service Paducah KY
827 PM CDT Sun Jul 16 2023
.UPDATE...
Issued at 826 PM CDT Sun Jul 16 2023
Convection has diminished locally for the time being. Attention
now shifts to potential for some thunderstorms in the overnight
hours. NAM/RAP/HRRR/SREF are all consistent in developing storms
over central Missouri that then track southeastward after
midnight and into the area. AMSU PWAT imagery and model analyzed
fields show an area of convergence at 850-700mb across the I-64
corridor of Missouri that makes for a plausible zone for
initiation of primarily elevated convection in the overnight. Some
lift is also apparent on upper level water vapor with another
small shortwave headed into northern Missouri. Updated the
forecast to delay the onset of pops just a bit but it seems
reasonably likely this activity will set off and move into the
area in some form overnight.
Mid-level lapse rates around 6.5 C/km and 30`ish kts of deep layer
shear are are evident on the 00z SGF RAOB and model analysis
fields and are projected to move across the area tonight. This
will lead to at least some threat for hail with elevated storms
with MUCAPE values around 2000 J/kg. While much of the area saw
some rain/outflow cooling from earlier convection parts of SEMO
did not and coupled with most low level moisture advection
(Dewpoints in the high 70s) some surface based instability may
linger as well. If any downdrafts can kick up initiating
boundaries this may set off a few storms in this region as well
and increased pops to 20-30% there. Whatever happens overnight and
into the morning will obviously have implications on where/when
convection develops tomorrow as well. Although with dewpoints in
the high 70s over Arkansas moisture return with even a little low
level advection will be strong and could lead to additional
destabilization behind convection.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 306 PM CDT Sun Jul 16 2023
Smoke and haze are currently dominating across the area and is
very evident on satellite. This has resulted in Air Quality Alerts
for IL and IN through this evening. The haze is also reducing
visibilities in some places to around 4-5 miles. Despite the haze,
highs are still looking to top out mostly in the 90s. A pocket of
energy aloft has already spurred storms over central MO.
According to the CAMs these storms are expected to move east and
diminish as they graze our northern areas. Though the HRRR has a
second round of storms developing over the same area and diving
southeast overnight and into tomorrow. This brings precip chances
to the remainder of the area tomorrow and tapering off tomorrow
night.
Tuesday a shortwave aloft comes through bringing more storm
chances to the area which could last through Wednesday morning.
Highs tomorrow and Tuesday will continue to be in the 80s and
lower 90s. Dewpoints start to creep up into the 70s on Tuesday and
conditions will start to feel a little more muggy.
.LONG TERM...(Wednesday through Sunday)
Issued at 306 PM CDT Sun Jul 16 2023
Wednesday onward there are precip chances nearly every day as
different pockets of energy move through the northwest flow aloft.
Wednesday will be hot and humid as the high pressure dome that has
been sitting over the southwest CONUS edges its way into the area.
Highs will be in the 90s with a few places pushing 100, and heat
indices will be in the 105-110 range for quite a few places.
Thursday will be a little better due to more cloud cover, but not by
much. Thursday will still see heat indices in the 100-105 range
during the afternoon. Friday will be slightly cooler and more
average after a cold front moves through as a broad upper level trof
deepens over the region. This cold front will also spur some showers
and thunderstorms for Friday. The weekend will continue with highs
in the 80s and drier conditions.
&&
.AVIATION...
Issued at 827 PM CDT Sun Jul 16 2023
Convection has diminished locally but additional showers and
storms are expected to redevelop over Missouri and approach the
area late tonight with some activity persisting into the day
tomorrow. Will be updating most of the TAF sites shortly to
reflect latest thinking on timing/placement of storms.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...JGG
SHORT TERM...SHAWKEY
LONG TERM...SHAWKEY
AVIATION...JGG
Area Forecast Discussion
National Weather Service Pittsburgh PA
740 PM EDT Sun Jul 16 2023
.SYNOPSIS...
An upper low over northern Minnesota is forecast to sweep across
Lake Superior and Ontario overnight and then push into Quebec on
Monday. Associated cool front will push into the Upper Ohio
River valley with showers and thunderstorms Monday afternoon and
evening.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Spotty diurnal showers are expected to gradually diminish this
evening with boundary layer stabilization. Satellite imagery and
METARs show broad area of smoke/haze from British Columbia fires
from the Dakotas into Ohio and visibilities have dropped into
MVFR levels. Used the HRRR smoke forecast to bring haze from
west to east into the area tonight.
&&
.SHORT TERM /MIDNIGHT TONIGHT THROUGH MONDAY NIGHT/...
Smoke models indicate a gradual decrease in smoke concentration
during the day so gradually removed it by the late afternoon
hours.
Potent upper low currently over northern MN is forecast to move
across Lake Superior late tonight and then Ontario into NW
Quebec on Monday. A surge of higher PWs and stronger deep layer
moisture transport is shown along with high probability of
showers and thunderstorms in a deep zone of positive theta-e
advection. Both WPC and SPC have marginal risks up for
Monday/Monday night rich seems reasonable given 40 knots of flow
at 500 mb, unidirectional southwest flow, and PWs in the 1.5 to
1.75" range.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Persistent pattern to continue with large upper high and extreme
heat over southwest states and troughing over the Great Lakes.
Next significant short wave trough arrives around Thursday with
increased chances of showers and thunderstorms as 30 to 50 meter
500 mb height falls spread across MI into OH. 12z ECMWF had left exit
region of 100 knot 250 mb IA jet max over the forecast area.
WPC has a marginal risk of excessive rainfall and CSU MLP has
low probabilities of severe. Mid level flow will remain strong
so severe potential will be dependent on instability as shear
more than sufficient to support severe weather.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Remaining isolated showers/storms will dissipate this evening.
Only issue overnight through 15Z or so Monday will be wildfire
smoke and its impact on visibility. For now, limited drop to 5SM
at ZZV/FKL and to 6SM for other TAF sites as thickest smoke
should remain off of to the north. However, this is a low-
confidence forecast and recognize that visibility could go lower
overnight.
Diurnal cumulus will begin to pop up by 15Z Monday, and showers
will begin to fire around midday in daytime heating on Monday.
Limited thunder mention to when confidence in precipitation
coverage is a bit higher, generally after 19Z at ZZV and 21-00Z
at other TAF sites. VFR will continue to prevail, but of course
any terminal that takes a direct hit from a storm could see
brief IFR visibility and gusty, variable wind.
.OUTLOOK...
Persistent eastern U.S. trough will foster continued shortwave
advection through the Upper Ohio River Valley through the week,
creating periods of showers/thunderstorms and restrictions.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Craven
NEAR TERM...Craven
SHORT TERM...Craven
LONG TERM...Craven
AVIATION...CL
Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Sun Jul 16 2023
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
A strong and persistent high pressure system will continue to
predominate through the week, resulting in near record temperatures
each day. An Excessive Heat Warning remains in effect across the
area with most places seeing widespread Major to Extreme HeatRisk.
Isolated shower and thunderstorm chances the next couple days will
mainly be confined to higher terrain areas of eastern and
southeastern Arizona.
&&
.DISCUSSION...
Latest satellite imagery reveals the remnants of a decaying MCS
moving steadily westward across the Baja Peninsula. This system
brought an influx of low-level moisture to the area overnight and
dewpoints at this hour remain above normal and several degrees
higher than at this time yesterday. Meanwhile, the increased
moisture has tempered the heating somewhat and it now appears
unlikely Phoenix will tie the daily record of 118 degrees set in
1925. Forecast high was adjusted downward to 115 degrees.
Nevertheless, the well above normal temperatures and increased
humidity are still creating oppressive conditions and the Excessive
Heat Warning remains in effect for today and the next several days.
Latest RAP analysis places the center of the mid-level anticyclone
near Las Vegas, resulting in a light easterly flow across the lower
deserts. This along with PWATs near 1.2 inches would normally
promote isolated thunderstorm activity, however the morning ACARS
sounding indicates a well-defined subsidence inversion near 700 mb,
which will inhibit convection this afternoon.
Models remain in good agreement, depicting the Monsoon high shifting
eastward towards the Arizona/New Mexico border Monday. Latest
deterministic NBM again suggests record breaking temperatures of 118
degrees in Phoenix, though temperatures a few degrees lower are
certainly possible if dewpoints are on the higher side of the
forecast envelope. Reaching the 110 degree mark is a near certainty
in Phoenix, which will make it the 18th day in a row with highs at
or above 110 degrees, tying the record set in June of 1974.
Meanwhile, there is also a discernible signal in the 12z HREF,
indicating isolated thunderstorm development late Monday afternoon
across southern Maricopa/Pinal Counties. Ensemble max wind gusts
suggest the potential for 60 mph, which will be strong enough to
produce areas of blowing dust and even additional thunderstorm
development a bit further north. There is roughly a 50 percent
chance of gusts reaching 35 mph in these areas, which will be
sufficient for at least localized reductions in visibility.
The Monsoon High will remain the predominant weather feature through
the week. Model ensemble suites generally indicate the center of the
high will migrate a bit eastward, with the ridge axis remaining
draped across Arizona. This will continue to translate into near
record temperatures each day as well as the continuation of the
streak of 110+ degree high temperatures for Phoenix. Also worth
noting is the forecast low temperature of 96 degrees in Phoenix
Wednesday morning would tie the all-time record for the highest low
temperature. When overnight temperatures are this high, the body has
a difficult time recuperating. With little to no relief from the
excessive heat overnight and the prolonged nature of the heat wave,
extreme HeatRisk will impact the general population including long-
time residents that are normally acclimated to the extreme
conditions.
Forecast uncertainty will increase midweek while low-level mixing
ratios are generally expected to decrease across the lower deserts.
Highest PoPs remain focused in the climatologically favored areas of
southeastern Arizona and the Mogollon Rim, but it is conceivable
thunderstorm activity, or at least an outflow boundary, will creep
closer to the lower deserts at least one day this week.
&&
.AVIATION...Updated at 2300Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather issues should exist through Monday afternoon under
periods of passing thicker high cirrus cigs. West winds will prevail
through the evening with some evidence continuing to show gusts
~20kt reemerging later in the evening with a well defined Gulf
Surge, though confidence is waning somewhat. Nevertheless, the
typical morning easterly wind should be temporally shorter than usual
with west winds becoming established again by late Monday morning.
Southeast California/Southwest Arizona including KIPL and KBLH:
Only periods of thicker high cirrus cigs will spill over SE
California terminals through Monday afternoon. Winds will remain out
of a southerly direction through the period with some oscillation
between SE and SW. Some occasionally stronger gusts would also not be
uncommon.
&&
.FIRE WEATHER...
Well above average temperatures are expected this weekend and much
of next week with highs reaching 112-120 degrees across the lower
deserts. Overnight relief will be limited with lows only falling to
the mid-80s to mid-90s. Minimum humidity will be around 10-20% this
weekend with overnight Max RHs around 30-50% for most areas. Low
level moisture will increase early this week as well as the
potential for thunderstorms across south-central Arizona. Gusty
erratic winds and dry lightning will be the main concern with any
thunderstorm that may develop. Winds will tend to follow typical
diurnal and terrain influences, with occasional afternoon gusts up
to 20-25 mph.
&&
.CLIMATE...
Record High Temperatures:
PHOENIX YUMA EL CENTRO
July 16 118 (1925) 116 (1960) 119 (1936)
July 17 116 (2005) 117 (2005) 121 (2005)
July 18 115 (1989) 117 (1960) 117 (2009)
July 19 116 (1989) 115 (2000) 117 (1978)
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Wednesday for AZZ530>544-
546-548>551-553>555-559.
Excessive Heat Warning until 8 PM MST Tuesday for AZZ545-547-552-
560-561.
Excessive Heat Warning until 8 PM MST this evening for
AZZ556>558-562-563.
CA...Excessive Heat Warning until 8 PM PDT Wednesday for CAZ560>570.
&&
$$
DISCUSSION...Hirsch
AVIATION...18
FIRE WEATHER...Smith/Salerno
CLIMATE...Kuhlman