Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/03/18
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
540 PM MDT Sun Sep 2 2018
.AVIATION...
00Z TAF CYCLE
Tstm activity continues to favor the high terrain of the west-central
and northern mtns as well as along a few sfc bdrys over the east
plains of NM. Brief MVFR conditions can be expected with any of the
strong storms as they pass. Removed VCTS across the NW at KGUP and
KFMN where new strong convection is not expected to develop the rest
of this evening. Some storms could drift into the RGV near KABQ,
KAEG, and KONM over the next few hours. The HRRR is depicting an
outflow bdry emanating from convection over the Sangre`s SW into the
RGV to KSAF down to KABQ later this evening from 02Z-07Z, and can see
this already occurring at KLVS. This may keep convection going later
toward midnight, but confidence is not high enough to see anything
more than a windshift and VCSH from this feature. The east plains
may see shower activity continue well into Monday morning.
24
&&
.PREV DISCUSSION...327 PM MDT Sun Sep 2 2018...
.SYNOPSIS...
A weak, but broad, trough of low pressure is over the southwestern
states with isolated to scattered showers and thunderstorms being
observed over portions of New Mexico. Thunderstorms have initially
developed over the higher terrain, but are beginning to expand into
lower elevations such as the eastern plains of the state. Storms
could sustain themselves into the overnight hours in the eastern
plains. A fairly similar extent of thunderstorm coverage is expected
into Monday and Tuesday while temperatures remain a few to several
degrees below average for early September. A weak cold front will
then back into the state Wednesday, keeping the cooler trend going.
&&
.DISCUSSION...
The longer wave trough over the western states is keeping mid-
tropospheric pressure heights lowered over the area and hence cooler
than average temperatures are prevailing. Moisture is highest over
the eastern and southern tiers of NM, running slightly above average
with regards to PWAT climatology, while areas within the northwestern
quarter of the state are running near to slightly below average.
Despite the cooler temperatures, the boundary layer has destabilized
sufficiently for high terrain storms to fire, and these are quickly
expanding over the eastern plains. This trend should continue through
the evening and overnight per the NAM/HREF/HRRR/RAP guidance.
Into tomorrow, the long wave trough will be retained, although an
embedded short wave will be lifting northeastward into CO. Similar
to today, storms on Monday are expected to initiate over the west
central zones surrounding the Continental Divide and and the central
mountain chain during the afternoon before expanding into the plains.
The southerly flow will back ever-so-slightly to more of a south
southeasterly component, allowing Gulf moisture to continue feeding
into the plains.
The trough will start to lose a bit more definition into Tuesday as
the speed max aloft begins to weaken. Again the plains will observe a
continued slight backing in the surface winds with moisture being
retained best over the eastern plains where PWATs will stay above an
inch. The northwest plateau will continue to observe less moisture
and lower storm prospects through Tuesday while the area-wide below
normal temperatures persist.
The weak back door cold front will ease into NM on Wednesday,
spreading some of the deeper moisture from the plains westward into
the Rio Grande valley and western portions of the state. This will
increase storm chances in these areas late Wednesday and into the
evening.
Recycling of moisture will keep storms in the forecast through
Thursday, but as the weekend approaches the strengthening eastern
Pacific high (west of southern CA) will begin suppressing storms and
cutting off moisture.
52
&&
.FIRE WEATHER...
Afternoon rounds of showers and thunderstorms are expected to
continue through most of the week with the focus for the storms to be
mostly on the higher terrain. A backdoor front will push down the
Eastern Plains on Wednesday, bringing with it a minor increase in
winds and slightly higher afternoon RH values. Humidity recoveries
are expected to remain excellent through the week with below normal
temperatures. A warming and drying trend is expected to being on
Friday as high pressure begins to build over the Southwest.
54/Fontenot
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
852 PM CDT Sun Sep 2 2018
.UPDATE...
Issued at 851 PM CDT Sun Sep 2 2018
Forecast in fine shape with just a couple minor changes made. HRRR
runs this evening continue to advertise a few late night showers
so will leave that in the forecast. Temperatures appear fine.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 147 PM CDT Sun Sep 2 2018
As of 1 PM, high pressure is over far northeast Montana and
northwest North Dakota, with a ridge stretching south into north
central SD. The brief period of gusty northerly winds this morning
to the present time is tied to the tighter pressure gradient between
the departing front and arriving high. These winds should gradually
diminish through the rest of the afternoon. Temperatures are
currently in the 70s under a mostly sunny. GeoColor imagery from
GOES-East does indicate a little bit of smoke over the area and you
can get a slight smell of it outside of our office.
The high in North Dakota will continue to the east this evening and
overnight, leading to low level winds veering to the southeast by
tomorrow morning. Should see winds becoming gusty out of the
southeast in the afternoon hours tomorrow (mean momentum transfer in
upper teens to lower 20s for most locations), as the pressure
gradient again increases between the departing high moving into the
Great Lakes region and another cold front moving into western ND and
far northwest SD by 00Z Tuesday.
The other item of concern is the precipitation potential overnight
into tomorrow. A mid level ridge axis will shift through the area
tonight, shifting winds aloft to the southwest and increasing warm
air advection. Some differences in the northward extent of the best
mid level moisture, with the NAM showing the greatest moisture and
northward extent. Will follow a general model consensus for sky and
precipitation potential. Looks like there will be a pocket of clouds
and maybe a few showers pushing north along the Missouri River after
midnight. Farther east, the departing high may may leave enough low
level dry air to attempt to hold off the clouds some. Overall,
expect at least partly to mostly cloudy skies tomorrow for most
locations.
As for PoP forecast, confidence is low on coverage/location, but did
try to show some slight chance PoPs for the initial push of warm air
advection into the south central part of the CWA (CAMs give varying
solutions but all in that general area). There is some instability
moving into the area tonight (MUCAPE gradient of 0 J/kg over
northeast SD to 500-1000 J/kg near the Missouri River), so will show
some thunder potential. If a storm got going, would expect some
small hail as they will likely be elevated and based in the mid
level warm air advection regime. Finally, another wave of
precipitation is possible over the far southeast CWA during the
latter part of the afternoon. This precipitation will be tied to a
surge of mid level moisture under south-southeast winds aloft ahead
of an upper low lifting northeast out of the Four Corners region.
.LONG TERM...(Monday Night through Sunday)
Issued at 241 PM CDT Sun Sep 2 2018
The long term starts out with a short wave trough out west moving
across the northern plains Monday night through Tuesday. At the
surface, a cold front will push across our cwa on Tuesday. There will
also be weak short wave energy coming into our region from the
southwest Monday night and Tuesday. All three of these features will
result in chances of showers and storms for Monday night into early
Tuesday evening. Otherwise, the upper level flow will be westerly
for Wednesday and Thursday. Modest upper level ridging will then
move over our region as upper level troughing moves into the western
U.S. Friday through the weekend. Thus, Tuesday night into Saturday
morning is expected to be mainly dry. Upper level troughing coming
through Saturday afternoon into Sunday will bring back some chances
of showers and storms. Temperatures through the period will be
mostly from near to 5 degrees below normal mostly in the 70s and
lower 80s. There will likely be some upper 60s in the northeast on
Wednesday. Along with these temperatures will come some fall-like
humidity.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 653 PM CDT Sun Sep 2 2018
VFR skies/vsbys are expected through the dark hours at all
terminals.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...SRF
LONG TERM...Mohr
AVIATION...TDK
Area Forecast Discussion
National Weather Service La Crosse WI
644 PM CDT Sun Sep 2 2018
.SHORT TERM...(This evening through Monday)
Issued at 208 PM CDT Sun Sep 2 2018
While there will be showers and storms around the area through
Monday, this is looking to be a relative lull in the heavy rain
threat. The boundary that had been south of the area the last
couple of days has become very diffuse. Still some hint of it
across central Iowa where there is a subtle wind shift and slight
increase in the dew points. There is also a cold front moving
southeast across Minnesota as high pressure builds in behind the
front over the Dakotas.
Looking at several runs of the RAP and the 03.12Z NAM, it looks
like both of these boundaries will be a player for the local area.
The weak boundary across Iowa is expected to shift north through
the evening while become even more diffuse while the cold front
gets pushed to about the Interstate 90 corridor overnight as the
high pressure moves east toward Lake Superior. The low level
moisture transport axis looks to be from Missouri into lower
Michigan, well ahead of the advancing cold front. The ML CAPE axis
also looks to remain southeast of the area, but enough remains to
maintain at least a threat of thunder. The main axis of showers
and storms is expected to gradually shift southeast across the
area this evening and primarily be out of the area for much of the
overnight hours.
The boundary pushed in by the area of high pressure tonight will
start to lift back to the north as a warm front Monday. This will
allow the moisture transport axis to shift back to the west and
while still weak, will be focused more into the area. This should
allow for a general increase in showers and storms through the
day, especially south of Interstate 90. While there could be a
brief period of heavy rain the storms Monday, there does not look
to be a threat of widespread heavy rain or flash flooding with the
general weak moisture transport and the highest precipitable
waters remaining south of the area.
.LONG TERM...(Monday night through Sunday)
Issued at 208 PM CDT Sun Sep 2 2018
Main concern is possible heavy rain/flood threat through mid-week.
The surface boundary is forecast to lift northward across the area
as a warm front Monday night ahead of an upper shortwave trough.
Warm advection and increasing low-level moisture transport will help
to foster showers/storms. The 02.12Z NAM focuses the strongest
moisture transport and convection north and west of the area.
However, confidence in details in this type of scenario with a
boundary lifting north is not all that high at this range given
potential contamination from convection. Locally heavy rainfall will
be possible with any storms given the environment.
If the warm front does lift north of the area could see a relatively
quiet Tuesday morning until the cold front approaches from the west.
At least modest mid-level height falls ahead of the broad upper will
overspread the region Tuesday afternoon and night. Expect
showers/storms to increase as the front slowly sags south Tuesday
into Wednesday. A very warm, anomalously moist environment will
favor the potential for heavy rain/flooding. Some uncertainty
remains as to where this potential will be highest and the degree of
training of storms that will occur along the front. However, the
later Tuesday into Wednesday period will be one to watch closely,
though, especially given antecedent conditions. Mid-level flow/shear
remains on the marginal side south of the front and lapse rates are
weak, but could see a few stronger storms later Tuesday. As the
upper waves passes to the east, surface high pressure will begin to
build south on Wednesday with drying across northern parts of the
area.
A generally weak upper flow pattern is expected late this week.
Surface high pressure across the northern Great Lakes should lead to
a period of drier weather late this week into the weekend over much
of the area. However, given the weak flow and suggestion that
various shortwaves may lift northeastward in weakly confluent flow
on the western periphery of the Southeast/Mid-Atlantic ridge, some
shower/storm chances may persist into late week, especially across
southern areas. Temps will cool from the 70s to low 80s early this
week to the upper 60s and 70s later this week behind the front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 644 PM CDT Sun Sep 2 2018
Showers and storms are southeast of LSE and RST and should remain
there for much if not all of tonight, with winds becoming light as
a weakening frontal boundary slides into the area. With earlier
rain, light winds, and some breaks in the sky cover at times (just
mainly high clouds), fog should be a pretty good bet later
tonight, some of which will become dense fog both LSE and RST. Not
entirely sure just how fast fog will develop, but a good first
guess is roughly 04-07Z, with the thickest fog expected either
side of sunrise, when visibility could be 1/4 mile or less,
particularly at RST (though possible at LSE as well). Fog will
likely lift into a stratus layer for a time Monday morning,
perhaps trying to scatter out for the afternoon as some additional
showers and storms attempt to develop later in the day. Confidence
is low in how much coverage of storms will exist through 00Z, with
much better chances arriving into Monday evening and night.
&&
.HYDROLOGY...
Issued at 208 PM CDT Sun Sep 2 2018
The highest potential for additional heavy rains and possible
flash flooding, appears to be focused on the late Tuesday
afternoon into Tuesday night period. The next cold front will be
advancing into the area with strong moisture transport focused
into the front. An axis of high precipitable waters, possibly in
excess of 2 inches, will reside ahead of the front. The concern is
how far north will the nose of the moisture transport axis be to
focus the heaviest rain threat. Also uncertain how much training
there will be ahead of the north/south oriented front that looks
to be fairly progressive.
Flooding continues along the Kickapoo River and for now, levels
continue to go down. See the latest flood statement for more
details.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...04
LONG TERM...JM
AVIATION...Lawrence
HYDROLOGY...04
Area Forecast Discussion
National Weather Service Bismarck ND
952 PM CDT Sun Sep 2 2018
.UPDATE...
Issued at 952 PM CDT Sun Sep 2 2018
Latest satellite imagery and surface observations continue to show
a mostly clear sky. Surface high pressure centered over the Devils
Lake region is now resulting in a weak southeasterly wind across
central North Dakota. Did lower overnight temperatures into the
40s for all of central ND based on current trends and dewpoints.
Lower level clouds in south central South Dakota still on track
to move across the southern border 12z-20z Monday. Have bumped up
cloud cover per latest satellite imagery and RAP13 925mb-850mb RH
field Monday morning into the afternoon, mostly for the James
River Valley. The CAM`s show isolated showers developing later
tonight in eastern South Dakota in association with a
strengtheninglow level jet. These showers are forecast to weaken
as they approach the border mid to late Monday morning.
The 00Z model runs are coming in and the NAM is slower and a bit
farther west with the convection Monday evening, initiating
between 00z-03z; while the HRRR and other CAM`s show an
initiation between 22z Monday and 00z Tuesday. And while the
thunderstorms are still contained initially in western North
Dakota per HRRR, the thunderstorms are farther east than where the
NAM places its thunderstorm solution at 03z Tuesday. A few strong
to severe thunderstorms Monday late afternoon and evening remain
in good standing at this time.
UPDATE Issued at 631 PM CDT Sun Sep 2 2018
Latest visible satellite imagery shows a clear sky for all but
the far northern tier counties, where mid and high clouds were
observed moving from west to east across the southern Canadian
prairies. A thin wisp of smoke aloft can also be seen stretching
from northern Minnesota back into central North Dakota and portions
of Montana.
Surface observations show dewpoints in the lower to mid 40s in
conjunction with todays high temperatures. These dewpoints
usually serve as a good proxy for overnight lows given a decent
radiational cooling inversion. Per BUFKIT soundings tonight,
central North Dakota should see good radiational cooling with a
clear sky and light winds. May need to lower temperatures a few
degrees across south central ND given the dewpoints mentioned
above, and will monitor the trends this evening before making any
changes. Scattered to broken low clouds (3500ft to 6500ft agl) in
south central and southeastern South Dakota were shifting north
very slowly. The RAP 925mb-850mb RH field captures this well, and
as our low level winds turn southerly and increase late tonight,
should see some of these clouds reach far south central and the
James River Valley after 12z Monday. Current forecast is on track.
&&
.SHORT TERM...(This evening through Monday)
Issued at 229 PM CDT Sun Sep 2 2018
Main forecast issue in the short term period will be temperatures
and thunderstorm chances late Monday.
Currently, high pressure is situated over western and central
North Dakota with nearly full sunshine over the entire forecast
area. Northerly winds were diminishing east with light and
variable winds west.
Last night was a good radiational cooling night with morning lows
this morning dropping into the upper 30s over portions of the
west. It looks to be another good radiational cooling night
tonight over central North Dakota, although we should remain in
the 40s. In the west it should cool quickly this evening but we
will see an increasing return flow on the back side of the
surface high late tonight. Adjusted lows downward most areas,
especially east and normally cool areas of the west.
A shortwave trough moving tracking across the southern Canadian
provinces will induce lee side cyclogenesis over the Canadian and
northern Rockies late tonight with the surface trough tracking
east to the Montana/North Dakota border by 00 UTC Tuesday. This
should allow for plenty of heating over easter MT and western ND
Monday afternoon within the thermal trough under sunny to mostly
sunny skies. This will set the stage for convection late in the
day on Monday, but moreso Monday night. We did raise high
temperatures across much of the central and especially western ND
Monday with some areas of the far west reaching the upper 80s. We
kept some slight chance pops in the far west but limited them to
the 21-24 UTC timeframe.
.LONG TERM...(Monday night through Sunday)
Issued at 229 PM CDT Sun Sep 2 2018
An unstable but capped airmass is expected Monday afternoon along
and ahead of the aforementioned surface trough. We expect a
moderately unstable airmass with steep lapse rates developing over
western North Dakota Monday afternoon. Initially capped, the
heating along the trough, the forcing from the mid level trough
and trailing cold front is expected to generate convection over
western ND late Monday afternoon into early Monday evening.
Although not perpendicular, the bulk shear appears to be at enough
of an angle to the surface trough that convection may be discrete
when it initially develops with shear becoming more parallel to
the trough and the cold front late in the evening and overnight.
Bulk shear is reasonable around 30 to 40 knots early Monday
evening. Thus during the first half of the evening we think
discrete supercells possibly transitioning to multicellular
clusters are possible. Large hail up to half dollar size and wind
gusts to 70 mph would be the main threats with cells that can
maintain a rotating updraft within this deeply mixed boundary
layer. Although directional shear and low level helicity is
present, the expected high bases, and high LCL`s should limit the
tornado potential.
As convection tracks into central ND, it will meet up with a more
strongly capped environment and by this time with the diurnal
trend in a downturn, surface based instability will be
diminishing. Thus our confidence for severe convection as the mode
transitions to possibly more of a QLCS structure, is less. With
the SPC upping the severe potential to a slight risk over western
and a bit of central ND Monday evening, we did add the mention of
severe wording in the gridded forecast and messaged this in social
media posts. Later shifts can adjust as needed over central ND as
we move closer to this timeframe.
Certainly as we go toward Tuesday morning models suggest
convection diminishing as it pushes into eastern portions of
central ND as the cold front outraces the convection. However
showers and isolated thunder chances will remain over the southern
James River Valley into early Tuesday afternoon.
By Tuesday evening, cool Canadian high pressure buildings in.
This will give us another taste of fall, with highs in the mid 60s
to lower 70s and lows in the upper 30s and 40s through Wednesday
night. Flow aloft will become zonal through mid-week, but no
disturbances are currently being resolved by long-range guidance.
A return to more active weather appears likely heading into next
weekend as an upper-level shortwave moves onto the Pacific
Northwest coast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 631 PM CDT Sun Sep 2 2018
A strong cold front will begin to approach the western terminals
towards the end of this taf period. Vfr cigs/vsbys are expected,
however, cigs around 3500ft agl are anticipated at KJMS by 18z
Monday as low level moisture and clouds shift from southern South
Dakota into southern North Dakota Monday morning. A vcts was added
to KISN/KDIK toward 00z Tuesday, which will be ahead of the advancing
cold front posing a risk for severe thunderstorms from 00z through
06z Tuesday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...KS
Area Forecast Discussion
National Weather Service Brownsville TX
316 PM CDT Sun Sep 2 2018
.SHORT TERM (Now through Monday Night): Satellite and radar
images continue to indicate convection developing along the
northern edge of the CWA as well as across the Mexican plateau
this afternoon. The 500mb low across the upper Texas coast and the
500mb high across northeast Mexico is providing subsidence across
deep south Texas but monsoonal moisture to the west and moisture
with the broad circulation associated with the upper level low to
the northeast warrant a mention of isolated showers and
thunderstorms across the northern ranchlands late this afternoon
and across the western portions of the CWA early this evening
especially as the HRRR continues to prog convection developing
across western and northern portions of the CWA late this
afternoon into early this evening.
Low to mid level moisture will remain high to the northwest and
northeast of deep south Texas Monday with the upper level ridge
across northeast Mexico providing subsidence across the Rio Grande
valley. Will likely see a repeat of today as far as temperatures and
rain chances so will go with persistence for temps and POPS Monday
and Mon night.
LONG TERM (Tuesday through Sunday): Deep tropical moisture will
increase across the eastern portions of deep south Texas on Tuesday,
with precipitable water values over two inches by Wednesday. The
elevated moisture will support higher rain chances across the CWA
Tuesday and Wednesday. The long term forecast will remain
challenging as the global models forecast, with high certainty, a
tropical system moving across the northeastern Gulf of Mexico Monday
through Wednesday. The system will then move inland along the north
Gulf Coast, where heavy rainfall will be possible. Impacts to the
CWA will remain scant at this writing. As such, isolated to
scattered showers and thunderstorms will continue locally through
the rest of the period as moisture lingers in the area under modest
mid level ridging. Warmer than average temperatures will continue,
with lows from 75 to 80, and highs from the mid 90s east to triple
digits west. Heat index values will be mostly in the 103 to 108
degree range.
&&
.MARINE (Tonight through Monday night): Seas were near 3 feet with
south to southeast winds near 8 knots at buoy020 this afternoon.
Moderate to strong southeast winds will develop offshore the lower
Texas coast tonight as surface low pressure across northeast Mexico
and surface high pressure across the eastern Gulf of Mexico
provides a strong pressure gradient across the western Gulf. Will
word SCEC for the offshore waters tonight as a result. Winds will
diminish across the coastal waters Monday as the pressure gradient
weakens across the lower Texas coast slightly but winds will be
slightly higher across the bay waters than offshore. Winds will
increase offshore the lower Texas coast Mon night but not as
strong as tonight.
Tuesday through Friday night: Light to moderate east to southeast
winds and low to moderate seas will prevail through the long term.
The current wave models do not develop much in terms of swell from
the system forecast to strengthen while moving into and across the
northeast Gulf during the upcoming wk. Scattered to numerous showers
and thunderstorms will however move toward and over the lower Texas
coastal waters.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 81 97 80 93 / 10 10 20 30
BROWNSVILLE 81 97 78 96 / 10 10 20 30
HARLINGEN 78 100 77 96 / 10 10 20 30
MCALLEN 81 102 80 99 / 10 10 10 20
RIO GRANDE CITY 81 103 79 101 / 20 10 10 20
SOUTH PADRE ISLAND 82 92 81 88 / 10 10 20 30
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
61/54/62
Area Forecast Discussion
National Weather Service Cheyenne WY
519 PM MDT Sun Sep 2 2018
.SHORT TERM...(This evening through Tuesday night)
Issued at 150 PM MDT Sun Sep 2 2018
Tonight...Cumulus field bubbling up nicely over the mountains. CAPES
of 500 to 1500 J/kg exist over the southern Nebraska Panhandle. With
best cumulus development over the southern Laramie Range, will hold
onto isolated thunderstorms into the evening over the southern Laramie
Range, and dry elsewhere based on cumulus development seen on visible
satellite imagery.
Labor Day...A slow moving shortwave trough aloft moves to southeast
Wyoming in the afternoon with a surface convergence axis setting up
just south of the Colorado state line, thus will continue with
isolated afternoon thunderstorms along and just north of the Colorado
state line.
Monday night...Isolated thunderstorms continue into the evening near
the Colorado state line, then end.
Tuesday...Weak westerly flow aloft with low level easterly upslope
over our counties. With a well defined low and mid level theta-e
ridge axis over our counties, expect isolated to scattered afternoon
showers and thunderstorms south of a Rawlins to Lusk line. NAM and
GFS MOS differ considerably on maximum temperatures, so will compromise
between the models for high temperatures.
Tuesday night...With plenty of low and mid level moisture continuing
over our counties and weak upslope, will continue with isolated to
scattered showers and thunderstorms all night, mainly along and east
of Interstate 25.
.LONG TERM...(Wednesday through Sunday)
Issued at 150 PM MDT Sun Sep 2 2018
12Z medium range models/ensembles show the persistent upper level trough
over the central Rockies finally exiting into the Great Plains by the
end of the week. Until then, the weather pattern will remain somewhat
unsettled, with widely scattered showers/tstorms and cooler than normal
temperatures. High pressure at the surface and aloft will bring drier
conditions and normal temperatures by Saturday. It will be breezy west
of the Laramie Range Saturday ahead of a upper level trough over MT.
The trough moves east along the US/Canadian border, driving a cold front
southward into the CWA. The GFS develops scattered convection along/behind
the front, with the Euro depicting little or no precipitation. Kept
next weekend/s forecast dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 516 PM MDT Sun Sep 2 2018
Confidence increasing that we will see some low stratus over the
southern Nebraska Panhandle tonight as moist southeasterly flow
develops. Main terminal to be impacted look to be KSNY and KAIA.
HRRR has timing around 10Z for KSNY and 12Z for KAIA. Will see
what happens with KBFF, but for now, kept them VFR.
&&
.FIRE WEATHER...
Issued at 150 PM MDT Sun Sep 2 2018
Will need to watch Carbon County through early evening with near
critical conditions, i.e., low humidities and wind gusts approaching
25 mph. Low humidities expected Labor Day afternoon over Carbon and
Converse counties, though fortunately winds will likely be under
warning threshold criteria. Minimal concerns Tuesday through Thursday
as humidities increase. Humidities lower once again over our western
counties Friday and next weekend.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...RUBIN
LONG TERM...MAJ
AVIATION...GCC
FIRE WEATHER...RUBIN
Area Forecast Discussion
National Weather Service Goodland KS
625 PM MDT Sun Sep 2 2018
.UPDATE...
Issued at 625 PM MDT Sun Sep 2 2018
Despite the moist, moderately unstable (1000-1500 J/kg mlcape),
and uncapped airmass in place over the Tri-State area this
afternoon -- scattered convection has largely been confined
south/east of Goodland and, even there, coverage has decreased
significantly between 22-00Z. The limiting factor this evening
appears to be forcing. Regional radar trends and the latest HRRR
simulated reflectivity guidance suggest little potential for
convection over the Tri-State area for the remainder of this
evening into tonight. The relative best potential for isold
convection between 00-06Z will be in far eastern portions of the
forecast area (Gove/Graham/Norton counties) -- in closer vicinity
to outflow attendant widespread convection in central KS -- and where
richer low-level moisture and near moist adiabatic mid-level
lapse rates are more likely to foster/sustain additional updraft
development.
&&
.SHORT TERM...(This evening through Monday)
Issued at 204 PM MDT Sun Sep 2 2018
Little has changed in the overall setup, with a broad trough over
the central Rockies and embedded waves contributing to weak
synoptic scale forcing. At the surface, front has stalled over the
northwest corner of the forecast area with low level southeasterly
flow advecting moisture into the area. Shear/instability
parameters are best over the far eastern areas where there is a
slight risk for severe storms capable of producing large hail/
damaging winds through the evening hours. In other areas, slow
storm motions, the mean 0-6km wind is near zero, combined with the
anomalously high moisture in place will result in localized heavy
rainfall/flash flooding. Storm coverage/intensity will gradually
diminish through the overnight hours. Areas of fog will develop
towards sunrise as boundary layer cools/saturated, with fog
gradually dissipating through Monday morning.
On Monday, looks like more of the same with little change in the
overall pattern. Southern areas again see the best combination of
shear/instability so may see a severe storm or two there. Storm
motions are higher compared to today, 0-6km mean winds actually
increase to near 20kts by the afternoon, which may mitigate flash
flooding concerns. Nonetheless, model QPF still showing some 1-2
inch bullseyes so cannot completely rule out the heavy rain/flash
flooding threat on Monday. Temperatures will be slightly below
normal due to persistent cloudiness.
.LONG TERM...(Monday night through Sunday)
Issued at 104 PM MDT Sun Sep 2 2018
An upper-level ridge will be centered over the Mid-Atlantic United
States Monday evening while a broad upper-level trough will dip into
the southwest United States. This will promote relatively strong
south-southwesterly upper-level winds over the Central High Plains
Monday through Wednesday. There is increasing confidence that this
set up could lead to heavy rainfall and potentially flash flooding
across the Tri-State area during this time period. Instead of a
typical diurnal pattern of afternoon showers and thunderstorms,
showers and thunderstorms will be possible essentially throughout
the entire time period between Monday night and Wednesday night for
most of the Tri-State Region.
With measurable precip over the past couple days and more expected
today, the ground will be relatively saturated when these
potentially heavy rains come in the beginning of the coming week.
This increases the confidence that flooding will be a concern in the
next few days, especially in urban areas or eastern portions of the
area where more rain has fallen during the Labor Day weekend. With a
few days before the heaviest rainfall expected Tuesday evening and
into Wednesday, there is still a lot of uncertainty about how much
rainfall there will be and where that rainfall will be located. It
appears likely that some locations will record up to an inch or more
of rain Labor Day through Wednesday.
Upper-level winds will begin to decrease in intensity towards the
latter half of the coming week, but they will generally remain
southerly or southwesterly until Friday evening when an upper-level
trough will usher in weak northwest flow aloft over the Central High
Plains. Scattered showers and thunderstorms will remain a
possibility through early Friday.
At this point, there is significant disagreement among model
guidance about the chances for showers and thunderstorms next
weekend. With the GFS keying in on an approaching strong longwave
trough progressing eastward from the Pacific Northwest, vertical
wind shear would increase and there would be some dynamic support
for showers and thunderstorms late next weekend. However, the ECMWF
model for example is less bullish on this approaching trough and
would tend to keep the Central High Plains dry on Saturday and
Sunday. For now, keeping a slight chance of showers and
thunderstorms over eastern portions of our area for Sunday.
High temperatures will start out in the upper 70s to low 80s Monday
and Tuesday, before cooling off to the low 70s for Wednesday and
Thursday after the heavy rains/abundant cloud cover expected on
Tuesday and Wednesday. After that, highs slowly warm up to the mid
70s Friday and low 80s for the weekend. Similarly, low temperatures
will be in the low 60s for Tuesday and Wednesday, then cool a little
to the upper 50s for Thursday through the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 625 PM MDT Sun Sep 2 2018
VFR conditions will rule through this evening at both terminals.
Fog and/or low stratus is expected to develop across portions of
northwest KS and southwest NE overnight, with IFR/LIFR conditions
possible between 09-13Z. At this time, the relative worst
conditions are expected at the MCK terminal. Expect fog/stratus to
lift/scatter to VFR by 15Z. Scattered thunderstorms may affect
either terminal Monday aft/eve, though confidence in convective
coverage/evolution remains too low to warrant explicit mention
with the 00Z TAF issuance. E or SE winds ~10 knots will prevail
this evening, followed by light/variable winds overnight, then
SE/SSE winds at 10-15 knots Monday afternoon.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...VINCENT
SHORT TERM...024
LONG TERM...PATTON
AVIATION...VINCENT
Area Forecast Discussion
National Weather Service Lincoln IL
1048 PM CDT Sun Sep 2 2018
.UPDATE...
Issued at 845 PM CDT Sun Sep 2 2018
The main area of convection remains anchored to our northwest this
evening, although we have noticed a slight east movement in the
convective band over the past couple of hours. The HRRR has been
consistently weakening the southern portion of the complex thru
late this evening and keeping the bulk of the activity to our
north, with additional development taking place, possibly along
the outflow boundary across our north late tonight which may tend
to increase the coverage over the far northern areas. Otherwise,
the rest of the forecast area should stay away from the rain and
remain warm and humid overnight with early morning lows holding in
the low to mid 70s.
The upper level ridge to our east at 500 mb is forecast to push a
bit further west into the Midwest on Monday which would keep any
convection widely scattered during the day. Several weak shortwaves
seen on the water vapor loop this evening to our southwest which
are forecast to track northeast along the western periphey of the
ridge and affect mainly west central and central Illinois on
Monday. This will result in a continuation of the low POPs
(isolated to widely scattered thunderstorms), especially during
afternoon and early evening hours. Another hot day again across
the region with afternoon temperatures well above normal for the
first week of September with highs in the upper 80s to lower 90s,
and heat index values in the mid to upper 90s.
Only minor adjustments made to POPs across the forecast area for
tonight along with some tweaks to the evening temperatures in the
grids, otherwise, the rest of the forecast is in good shape. No
ZFP update needed at this time.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 305 PM CDT Sun Sep 2 2018
The forecast remains hot and humid with periodic chances for
showers and thunderstorms to wrap up the holiday weekend. Overall,
the forecast area is trapped between a more progressive
southwesterly flow from a general trough at 500mb over the
western half of the CONUS... and an upper ridge over the
southeast. The rest of the forecast relies on the interaction
between the two to drive the local weather...as well as the
interaction with a weak tropical system moving moisture into the
region for the latter half of the week.
Continued southerly flow at the surface further reinforcing the
warm temps streaming into the midlevels. Temps definitely on the
warmer side of guidance through today. With continuity in mind,
have gone more diffuse with the pops for tomorrow, with a diurnal
assist with heat of the day. Best chances for impact may be NW of
the IL River Valley with the more active southwesterly flow,
general airmass showers/TS still cropping up with the unstable
airmass. Overnight lows today, once again, not dropping far, into
the low to mid 70s. Tomorrow a very similar day to today...hot,
humid, increasing clouds translating into afternoon chances for
showers/thunderstorms.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 305 PM CDT Sun Sep 2 2018
Models still having some issue with the showers to the NW and how
far they creep while the upper ridge strengthens and pivots the
flow aloft to a more longitudinal direction by midweek. Low
chance pops are all over the place beyond midweek, reflecting the
uncertainty, as well as the general unstable airmass in the
afternoons. Furthermore, the development of a tropical system in
the Gulf pushing into the ridge may further complicate the
extended, as moisture is pulled into the Miss River Valley from
that system. Until the pattern evolves later in the week, the
region will not get out of the hot/humid/chance thunderstorms
regime. After midweek, the forecast is starting to morph with both
the influence of the Gulf system moving onshore, as well as
another trough moving across southern Canada, and potentially
trying to dislodge the hot airmass in place.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1045 PM CDT Sun Sep 2 2018
VFR conditions are expected this forecast period. The large area
of convection that occurred to our west and northwest into early
this evening produced an outflow boundary which has pushed south
and east of GBG late this evening. Isolated showers and storms
were trying to develop ahead of this wind shift line but are
struggling due to poor mid level lapse rates. Will keep an eye
on the progress of the development and may need to add VCTS to
PIA but will make that a last minute decision. Otherwise, little
change from previous thinking with quite a bit of cirrus moving
in from the west from the weakening storms, which looks to affect
mainly PIA and BMI.
Forecast soundings indicate quite a bit of cumulus will once again
develop by early Monday afternoon, which may lead to a widely
scattered TSRA but where that may occur is a low probability
occurrence this far out in the forecast period, so will hold off
including in this set of TAFs. Light southerly flow tonight at 10
kts or less, will increase out of the south on Monday to 10 to 15
kts with a few gusts up to 20 kts possible in the afternoon, before
diminishing to 10 kts or less by 00z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Smith
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1104 PM CDT Sun Sep 2 2018
.SYNOPSIS...
Issued at 312 PM CDT Sun Sep 2 2018
A stagnant H5 pattern remained in place across the lower
48 this morning. High pressure was located over sern Virginia. HT
rises in association with the high were relatively minor this
morning with rises on the order of 10 to 30 GPM. Those Ht rises were
focused across the mid atlantic states. Further west, a broad trough
of low pressure extended from a closed low in Saskatchewan, south
into the swrn CONUS. East of this trough, swrly flow aloft was
present from the swrn CONUS to the central and srn Plains. Within
this swrly flow, a shortwave was noted across western Kansas and it
has since moved into swrn Nebraska per WV imagery. Some light
precipitation was occurring during the late morning hours across far
southeastern areas of the forecast area. Elsewhere, skies were
partly to mostly cloudy and 3 PM CDT temperatures ranged from 72 at
Gordon to 84 at North Platte.
&&
.UPDATE...
Issued at 741 PM CDT Sun Sep 2 2018
Just an isolated rain chance overnight and Monday morning
according to a blend of the HRRR, RAP, HREF and model consensus.
Rain chances should increase Monday afternoon. A new forecast is
in place for the rain chances and fog overnight and Monday.
UPDATE Issued at 635 PM CDT Sun Sep 2 2018
The model consensus is showing a strong signal for very low
ceilings and fog Monday morning, mainly across the higher
elevations of the Sandhills and southwest Nebraska. A new
forecast is in place for areas of fog late tonight and Sunday
morning.
&&
.SHORT TERM...(This evening through Monday)
Issued at 312 PM CDT Sun Sep 2 2018
Tonight and Monday...Precipitation chances are the
main forecast challenge over the next 24 hours. For Tonight: Another
round of showers and embedded thunderstorms, some with heavy rain
will cross the Central Plains tonight. The latest GFS, NAM12 and
HRRR solutions have the best forcing just off to the south and
southeast of the forecast area tonight. The WARW soln however, does
develop some precipitation along the the surface boundary, which
currently extends from far swrn Nebraska, into central and the far
northeastern portion of the forecast area. That being said, with the
surface boundary in play and weak forcing INOVF the boundary, did
not totally eliminate pops from the fcst tonight in the southern and
eastern portion of the forecast area. Elsewhere, scaled back pops or
eliminated them all together in the west and northern forecast area
as forcing is limited, along with the entrainment of drier air from
across the border in South Dakota. On Monday, a second round of
precipitation will begin to push into southwestern then central
Nebraska late in the day. The latest NAM12 and GFS solutions lift
some decent forcing across central Colorado, which then approaches
northeastern Colorado and swrn Nebraska late in the day. With good
agreement between the NAM12 and GFS solutions, as well as support
from the WARW, decided to increase precipitation chances from swrn
into central and north central Nebraska for Monday afternoon/Monday
night. Right now, the threat for severe storms appears fairly low,
with the main threat being heavy rain. Looking at fcst PWATS for
tomorrow afternoon they are running 1.0 to 1.5 inches, so localized
heavy rain is possible and will continue to mention the threat in
the HWO.
.LONG TERM...(Monday night through Sunday)
Issued at 312 PM CDT Sun Sep 2 2018
High pressure aloft will remain
anchored across the Mid Atlantic through Thursday. This will place
the forecast area in west southwesterly flow aloft through mid week.
This along with abundant low level moisture, will be favorable for
off and on rain for the bulk of the upcoming week. Confidence in
drier conditions really doesn`t materialize until after Friday as
the high finally breaks down in the east. A midlevel trough of low
pressure, will track through the Central Plains Saturday, forcing
much drier air into western and north central Nebraska late Saturday
into Sunday. In the meantime, precipitation chances will be fairly
high and temperatures at or slightly below normal for the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1104 PM CDT Sun Sep 2 2018
The model consensus continues to show a strong signal for very
low ceilings and fog Monday morning, mainly across the Panhandle,
the Sandhills and southwest Nebraska. IFR/LIFR in fog and very
low ceilings is expected 09z-15z Monday. MVFR/IFR ceilings are
expected 16z-22z Monday across areas along and east of highway
83. VFR is expected elsewhere.
Isolated showers and thunderstorms are expected overnight until
21z Monday. Scattered showers and thunderstorms are possible
after 21z Monday, mainly across swrn and ncntl Nebraska.
Thunderstorm chances are expected to increase Monday evening with
the approach of an upper level disturbance, currently across New
Mexico.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CDC
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Lake Charles LA
801 PM CDT Sun Sep 2 2018
.UPDATE...A flash flood risk remains in area this evening,
even though the overall convective structure has decayed. A
nocturnal flare up is expected later tonight into early Monday
which may result in high rainfall rates and totals. The main focus
is expected to be generally west of a DeRidder to Pecan Island
line. The hi-ress HRRR depicts a wide swath of greater than 2
inches with some totals over 8" for multiple runs and for this
reason WPC has upped the risk to moderate for tonight/early
Monday. Rainfall totals in the FAA have been upped to reflect
this, however the areal/spatial coverage of the watch has not
changed.
&&
.PREV DISCUSSION... /issued 644 PM CDT Sun Sep 2 2018/
DISCUSSION...
For the 03/00Z TAF Issuance.
AVIATION...
A mid/upper level swirl noted along the coast near the
Texas/Louisiana border will slowly move west into Southeast Texas
tonight into early Monday. Plenty of tropical moisture is noted
with this feature. As is typical for these systems, beginning to
see a slow decrease in shower activity this evening through about
03/03Z. Then nocturnal shower activity will again re-developed and
become more focused near the center during the overnight.
Therefore, prevailing shower activity is expected to move back
into the KBPT/KLCH by 03/08Z and continue through 03/18Z. Shower
activity will develop at other sites with daytime heating between
03/12Z and 03/18Z. Mainly MVFR conditions are expected, however,
occasional IFR to LIFR will be possible in the stronger showers.
Rua
PREV DISCUSSION... /issued 400 PM CDT Sun Sep 2 2018/
DISCUSSION...
Water vapor/88D imagery show mid/upper-level low spinning over the
coastal waters just south of Jefferson County this afternoon,
while sfc analysis shows a coastal trof in place from the middle
TX coast newd. Combo of these features in a very moisture-rich
airmass is producing, as expected, widespread showers with
scattered storms across the entire region. Latest scan of hourly
rates shows heaviest rains likely only producing amounts around 1
inch/hour and this has been the trend for much of the day. On the
plus side, much of the area has remained in the 70s under dense
cloud cover and precipitation.
Needless to say, a messy forecast today. In the short-term, will
continue to see widespread showers/few storms through the
remainder of the afternoon and past sunset as the mid/upper low
continues its slow wwd trek. High res guidance is indicating a
marked increase in precip again later tonight, mainly over sern
TX. As we move through Labor Day, the low is progged to open up as
it gets pulled into the wswrly flow aloft, ejecting enewd...
leaving the area in a weakness aloft. A continued deep srly flow
will maintain a very moisture-rich airmass with forecast soundings
indicating PWAT values remaining well above 2.0 inches. Therefore
very elevated POPs remain in the forecast for tomorrow, with best
QPFs lingering across the wrn portions of the forecast area.
As far as flood watches go, here is the current plan for the WFO
LCH CWA...we will be maintaining the current Flash Flood Watch for
Acadiana and portions of swrn LA through its scheduled expiration
time of 00z/19CDT. Shortly thereafter, we will likely be issuing a
new Flash Flood Watch, this time for all of sern TX plus the swrn
1/2 of our LA zones (essentially Beauregard to Jeff Davis to
Vermilion) which will run until 00z tomorrow evening. Mean areal
QPFs of around 4 inches are noted for coastal sern TX, then
tapering downward as you head ewd. Of course likely higher amounts
are expected.
Next up...newly minted Potential Tropical Cyclone #7 off the sern
coast of FL is forecast to continue moving nwwd while steadily
strengthening as it moves into the ern Gulf. Latest track
guidance indicates this system moving ashore near the mouth of the
MS River early Wednesday as a strong tropical storm (named
Gordon). On this track, the primary impacts for our forecast area
would be another round of elevated rain chances, with highest POPs
over the Atchafalaya Basin, starting Tuesday and lingering
through mid-week as the system continues nwwd across the MS Delta
and into nwrn LA. Current mean QPFs show the potential for another
1-2 inches across the ern 1/2 of the area, but obviously this
will be tweaked as we move closer to the event.
Things don`t look to improve much once Gordon departs the region
as the area remains under a weakness aloft...combined with
continued copious moisture, expect elevated rain chances to linger
right on through the end of the forecast period.
MARINE...
For now, no headlines are included on the coastal waters as
progged wind speeds remain below 20 knots. Will have to monitor
over the next day or so to see how wave height forecasts go for
swell purposes.
CLIMATE...
A quick recap of some climatological Summer (June through August)
statistics.
Lake Charles (records date back to 1895)
-3rd warmest Summer (84.3 degrees - record: 85.3/2011)
Lafayette (records date back to 1893)
-6th warmest Summer (83.6 degrees - record: 85.2/2011)
New Iberia (records date back to 1948)
-7th warmest (tie) Summer (83.0 degrees - record: 84.9/2011)
Beaumont/Port Arthur (records date back to 1901)
-8th wettest Summer (26.14 inches - record: 71.42/2017)
-10th warmest (tie) Summer (84.3 degrees - record: 86.3/1902)
Alexandria (records date back to 1892)
-finished just outside the top ten warmest Summers
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 72 88 71 90 / 40 60 20 30
LCH 74 84 74 87 / 70 80 30 50
LFT 74 87 74 89 / 50 60 20 50
BPT 77 84 76 86 / 80 80 40 50
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Flash Flood Watch through Monday evening for LAZ030-041-042-052-
073-074.
TX...Flash Flood Watch through Monday evening for TXZ180-201-215-216-
259>262.
GM...None.
&&
$$
PUBLIC...05
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
847 PM CDT Sun Sep 2 2018
.UPDATE...
847 PM CDT
Evening Update...
Locally heavy rainfall threat remains across far
northern IL this evening/overnight, while severe thunderstorm
threat diminishes. No changes planned to flash flood watch extent
at this time.
Linear complex of thunderstorms stretches from the Quad Cities to
far southeast WI per regional radar at mid-evening. LOT 88-D
depicts an outflow boundary which has surged east-southeast from
these storms, slowing their eastward progress, with a weaker and
largely elevated nature to convection than had occurred to our
northwest earlier this afternoon/evening. Despite RAP analysis of
2000 J/kg of MLCAPE ahead of this complex of storms, the advancing
outflow boundary, decreasing deep layer shear to the
east/southeast and a slowly cooling nocturnal boundary layer will
likely limit the potential for localized severe wind gusts with
these storms. Locally heavy rainfall amounts are thus the primary
concern with these storms through late evening, as they remain
organized in a southeast to northeast fashion parallel to the low-
mid level wind field. With storms currently across portions of
north central IL which saw heavy rainfall last night, and early
Friday, will have to watch for any additional flood concerns.
Dual-Pol data suggests weaker convective elements have resulted in
a decrease in instantaneous rainfall rates over the past 1-2
hours, though slow movement of line will maintain potential for
training across portions of the area. Had issued a flood advisory
for this area earlier as convection moved in, though will continue
to monitor trends over next few hours in case upgrade to flash
flood warning headlines become necessary for a smaller portion of
the advisory area.
High-res guidance indicates an overall weakening trend to storms
over the next few hours, though with focus for additional
development remaining over the northwest half of the cwa into the
overnight hours.
Ratzer
&&
.SHORT TERM...
230 PM CDT
Through Tonight...
The main concern will once again be heavy rainfall potential across
north/northwest portions of the forecast area. Not much has
changed synoptically from yesterday with a large high parked over
the eastern half of the country with a cutoff upper trough over
the west and active flow across Canada and the northern Plains.
The area has become quite unstable but there is little in the way
of forcing currently overhead aside from some weak forcing lifting
northward into the southern CWA. Have seen a few showers pop up
down towards Kankakee but with fairly week deep layer shear these
have not been able to maintain themselves. Larger scale forcing is
to the west across Iowa and moving toward the northwest section
of the forecast area. Thus expect northwest areas to see better
development of isolated to scattered showers and thunderstorms
through the afternoon, though something may pop op elsewhere in
the forecast area.
The impulse from Iowa will draw nearer this evening and expect
that there will be much higher coverage of showers and
thunderstorms, this evening and into the early overnight hours
over the northern and western forecast area. Expect a more
southwest to northeast orientation of storms, at least initially,
but this may become more west to east with time. Training cells
with very heavy rainfall are expected once again and will issue a
Flash Flood Watch for Ogle, Winnebago, Boone, McHenry and Lake
Counties for this evening and overnight. Many of these areas
received 3 to 5 or more inches of rain yesterday and last night.
Am a little less confident in the eastern extent of the watch as
the more persistent activity may be just to the west but given
earlier rainfall and higher degree of urban landscape opted to
include these areas in the watch. Any storm may bring very high
rainfall rates and training of cells would bring the potential for
several inches of rain where it persists. Will also need to
monitor severe potential though lower end deep layer shear may be
a limiting factor, though downdraft CAPE values are increasing.
Damaging wind gusts would be the main severe threat with a lesser
hail threat given the warm atmosphere but strong instability. May
see some of the shower and thunderstorm activity spread south and
east late tonight but am not terribly confident in this occurring.
MDB
&&
.LONG TERM...
230 PM CDT
Monday through Sunday...
An active period of weather looks to continue over portions of
northern Illinois and northwest Indiana through the upcoming week.
Northern Illinois and northwest Indiana will remain hot and humid
through midweek with periodic precip chances as we remain on the
periphery of a strong upper ridge centered over the mid Atlantic
Coast. Quasi-stationary boundary that has been over the area a
couple days now is forecast to be in the vicinity of far northern
Illinois once again on Monday, serving as the focus for the
greatest thunderstorm potential. Farther south, expect a mix of
sun and clouds in the warm sector, but otherwise hot and humid
conditions with temperatures pushing into the upper 80s to near
the 90 mark. Low to mid 70 dew points will persist resulting in
heat indices in the mid to upper 90s. Guidance indicates the jet
will shift north to northern Wisconsin which leaves sub-marginal
deep layer shear locally. Depending on how much diabatic heating
occurs given the usual limiting factors of convective debris and
cloudiness, it`s still possible that we see moderately strong
instability develop during the afternoon which would support at
least a localized severe threat.
The ECMWF continues to have a good signal for dry weather on
Tuesday as the upper ridge axis retrogrades slightly towards the
Appalachians and precip chances shift farther north and west as a
result. Meanwhile, the GFS is indicating its typical broad-brushed
afternoon convection despite showing the best forcing to our west
and north. Favoring the dry European solution for Tuesday, which
given the closer proximity to the upper ridge and lower precip
chances/cloud cover should present the best chance for some more
widespread 90 degree temps over the CWA with resulting heat
indices near 100F.
Pattern is expected to become slightly more progressive by
Wednesday as strong vort moves east across Canada and upper
ridge axis gets nudged back east. Stalled frontal boundary over
MN/WI should start to sag back south again Wednesday with precip
chances returning locally. Strong surface ridge building across
the Upper Midwest will help to drive some cooler air into the
Great Lakes with baroclinic zone stalling over the region through
the remainder of the week. The end result will be a decent
north/south temperature gradient over the CWA from Thursday into
next weekend with additional precip chances in the vicinity of the
baroclinic zone.
Deubelbeiss
&&
.AVIATION...
For the 00Z TAFs...
645 pm...Two primary forecast concerns are thunderstorm chances
through the period and wind directions Monday.
Isolated showers developed across the Chicago terminals earlier
this afternoon and are lifting northeast. Trends would support
mainly dry conditions for the Chicago terminals for the next few
hours. Focus is for a line of thunderstorms from eastern IA into
southern WI which will slowly sag into the rfd area in the next
few hours. This line is expected to remain northwest of dpa/ord
into this evening. Additional thunderstorms are expected in this
same area later this evening into the overnight hours. Its
possible that some of this later activity moves toward the
Chicago terminals Monday morning...perhaps after sunrise.
Confidence is too low for any mention during this time period.
All of this convection is likely to push some larger outflow
boundary south into northern IL by Monday morning making for a
difficult wind forecast. Southerly winds are likely to continue
this evening with some type of shift east or northeast by
morning. Wind directions may be quite variable depending on this
outflow...where it moves and any ongoing convection. Whether from
this boundary or with a traditional lake breeze...easterly winds
are then expected at the Chicago terminals by mid/late Monday
afternoon. Changes to the wind forecast can be expected with
later updates.
This boundary or other outflows from morning convection will
likely allow new thunderstorm development Monday afternoon. While
the current Chicago area tafs are dry...the best timing for any
additional thunderstorms appears to be Monday afternoon. Thus...
later tafs may need thunder mention for Monday afternoon.
Mvfr cigs are possible toward morning and then through late
Monday morning before lifting to a low vfr deck. Maintained
scattered mention as confidence remains low. cms
&&
.MARINE...
230 PM CDT
Low pressure will move east across the Great Lakes through Monday
while a cold front sags south across Lake Michigan through the
day Sunday. Fresh south breeze will prevail out ahead of the front
for today and tonight, then expect winds to veer to the northeast
and east behind the weak front on Monday. Another low is expected
to lift from the central Great Plains Tuesday to northern Lake
Michigan Tuesday night. Fresh to strong southerly breeze is
expected ahead of the front through the day Tuesday.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Flash Flood Watch...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008 until 7
AM Monday.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Pueblo CO
259 PM MDT Sun Sep 2 2018
.SHORT TERM...(This evening through Monday)
Issued at 256 PM MDT Sun Sep 2 2018
Currently...
Showers and a few thunderstorms were noted over the higher
elevations of the forecast area at 2 pm. Over the valleys and
plains, mainly variable high cloudiness was noted. Radar indicated
an MCV feature was still spinning over NC Pueblo/SC El Paso
county. Dwpts across the region were around 60 along the KS/CO
border/50s across most of the plains and 30s and 40s in the
valleys. SPC meso page shows about 1000 J/kg of cape was advecting
into the Pikes Peak region from the northeast. CAPE values of
500-1000 were noted over most of the SE Plains. Bulk Shear was
modest along the CO/NM border with values approaching 40 knots.
This shear was associated with a jet pushing across the s tier.
Rest of Today into Tonight...
HRRR has been persistent all day showing showers and storms
initiating along the I-25 corridor, and see no reason to believe
this will not happen. MCV over Pueblo/EL Paso county will likely be
the initiating point in an hour or so. Higher CAPE advecting towards
this feature should allow for sufficient juice to keep storms going
once they develop. Given that the better shear is farther south,
storm intensity should remain below severe limits although gusty
winds will be possible. As afternoon progresses into early evening,
expect more storms to fire along the entire corridor.
Radar has shown storms moving towards the west all day. Believe this
may change a bit as storms become deeper, and outflow may allow them
to propagate slowly eastward later this evening. Storms over the far
eastern plans may be few and far between early this evening but
should pick up later this evening.
Short range guidance shows that another mid level circulation is
likely to develop around the Trinidad/Walsenburg region later this
evening and move slowly north. This will help deepen the easterly
flow over north of the low. This should keep showers and storms
going on the plains, especially in the greater Pueblo/Pikes peak
region through the nighttime hours. For this reason, kept rather high
pops over parts of the region throughout the night. Without saying.
most of the night will remain cloudy over the fcst area.
Given the moist flow over the area and the circulations in the area,
some localized heavy rain will be possible, and burn scar flooding
will be possible.
Tomorrow...
Circulation will lift into NE CO tomorrow. Guidance products show
modest drying as flow becomes WSW throughout a good part of the
column over most of the area by tomorrow afternoon. This should
limit the amount of precip over the region, with the overall best
chance of precip over the higher terrain tomorrow. Area will still
be in cyclonic flow aloft so this should keep a bit of synoptic lift
over the fcst area. far east plains during the afternoon may also
see a bit better chance of precip as compared to the rest of the
plains.
Temps tomorrow will be a bit cooler than today with highs in the 70s
to L80s plains and 60s and 70s valleys.
.LONG TERM...(Monday night through Sunday)
Issued at 256 PM MDT Sun Sep 2 2018
Unsettled weather will continue Monday night into the middle of the
week with southwesterly flow aloft continuing to bring a series of
weak disturbances across southeast Colorado. Abundant moisture and
the weak disturbances will combine to produce showers and
thunderstorms across much of the forecast area. The primary concerns
with any thunderstorms will be locally heavy rainfall which could
cause problems for area burn scars, but severe weather appears
unlikely. A cold front moves south through the eastern plains,
bringing cooler temperatures Wednesday and Thursday. Expect highs to
be in the 70s at the lower elevations both Wednesday and Thursday.
The chance for showers and thunderstorms will continue each
afternoon and evening through about Thursday. By Friday, the upper
level ridge axis begins spread across the four corners region and
into Colorado. The moisture plume shifts eastward and drier and
warmer conditions will be on the way for Friday, Saturday and
Sunday. Expect highs to warm from the upper 70s and 80s Friday on
the plains to the 80s and around 90 degrees on the plains by Sunday
afternoon. Stark
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 256 PM MDT Sun Sep 2 2018
Lots of clouds will be over the region, especially tonight and
into tomorrow morning. A Monsoon disturbance will move across the
region tonite and this will likely keep showers going through the
nighttime hours, especially at KCOS. Main concern is how low cigs
will get at KCOS and KPUB, and this will be dependent on how
saturated we can get the lower atmosphere. Best chance for lower
cigs will be up at KCOS, and these lower cigs/showers may last
into mid morning. By tomorrow afternoon, VFR conditions
anticipated across the entire region.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...STARK
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Tulsa OK
938 PM CDT Sun Sep 2 2018
.DISCUSSION...
Much of the scattered convection that developed across the area this
afternoon has dissipated this evening. Some activity continues across
south central Kansas and central Arkansas. Available guidance
suggests that it is not out of the question for a few showers to
redevelop overnight in our area, and thus, we see no reason to
remove the slight chance POPs in the ongoing forecast. Temperature
trends seem reasonable as well. Latest HRRR and NAM continue to
spread low clouds into srn areas late tonight and then northward
Monday morning. Have made slight adjustments to sky trends to
reflect a later arrival of low clouds.
Latest data continues to support an increasing coverage of showers
and thunderstorms Monday/Monday night as precipitable water increases
to about 2.0" during this period (near the max average for this time
of year) and upper low over sern TX approaches.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...69
Area Forecast Discussion
National Weather Service Tucson AZ
305 PM MST Sun Sep 2 2018
.SYNOPSIS...Scattered thunderstorms mainly from Tucson eastward
through Labor Day. A slightly drier regime occurs Tuesday into
Friday with isolated thunderstorms mainly near the New Mexico
border. High temperatures will be a few degrees below normal through
Wednesday, warming to near normal Thursday into next weekend.
&&
.DISCUSSION...Satellite imagery this afternoon showed partly cloudy
skies across much of southeast Arizona. A few showers and
thunderstorms had also developed mainly east of a line from about
Gila Bend to Sierra Vista. Surface temperatures ranged from the low
90s around Tucson to the mid 70s across Cochise County where cloud
cover has limited the extent of heating so far today.
The pattern was defined by an upper trough draped across the
southwestern states, which is progged by various NWP models to
deepen slightly as it pushes very slowly eastward into NM over the
next few days. As such, additional dynamics for storm development
will be in place today into Labor Day, with isolated to scattered
showers and storms in the forecast into tomorrow evening. In the
near term, this thinking was consistent with the latest solutions
from the HRRR, U of A and other local WRFs. The best chance for
measurable rainfall at KTUS is thought to be this afternoon or this
evening as suggested by the 02/20Z HRRR and 02/12Z U of A WRFNAM.
However, the continued robust westerly flow will work to push deeper
moisture eastward by Tuesday, confining convection to areas mainly
east and south of Tucson, and especially near the AZ/NM border. This
trend is expected to continue through Friday, when the trough
finally moves out and high pressure off the southwest coast of
California advances eastward. This will draw drier air into the
state on northerly flow aloft. There will still be some low level
moisture capable of supporting a few buildups, but activity should
by and large be limited this weekend.
High temperatures through Wednesday will be 3-5 degrees below
average. An increase in heights will then warm temperatures to
within a degree of average Thursday into next weekend.
&&
.AVIATION...Valid through 04/00Z.
Scattered -TSRA/-SHRA mainly from KTUS vicinity eastward to the New
Mexico state line into Monday morning. Cloud decks from KTUS
eastward 8-12k ft AGL along with SCT-BKN clouds AOA 20k ft AGL. West
of KTUS, FEW-SCT clouds around 10k ft AGL. SELY/SWLY SFC wind
generally less than 12 kts, except gusts up to 40 kts near stronger
TSRA. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Scattered thunderstorms mainly from Tucson eastward
to the New Mexico state line through Monday. A drying trend will
then occur Tuesday into next weekend, with only isolated afternoon
and evening thunderstorms east of Tucson. Expect terrain driven 20-
foot winds at less than 15 mph, with brief strong gusts possible
near thunderstorms.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Carpenter/Pegram
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