Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/13/21
AREA FORECAST DISCUSSION
National Weather Service Albany NY
953 PM EDT Sun Sep 12 2021
.SYNOPSIS...
A cold front moving southward across the region will bring
scattered to numerous showers and thunderstorms into tonight.
Some thunderstorms could become severe with locally heavy
rainfall. Following the passage of the cold front, dry weather
briefly returns on Monday before additional rounds of showers
and thunderstorms arrive Tuesday into Wednesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
MESOSCALE UPDATE...While there is no doubt moisture transport
advection continues across the region as dewpoints remain well
into the 60s and PWATs continue to climb (currently 1.85" per
our 00z sounding). Ample bulk shear, 50-60kts, remains in place
with upstream convection likely tied to EML (at or just above
H700) as seen in the 00Z BUF sounding. This convection along and
south of Lake Ontario was along the frontal zone and within
that aforementioned EML and higher moisture transport. As we
progess through the early nighttime period, this convection
should remain elevated to reduce severe wind potential. However,
still can not rule out a deeper bow convective element making
its way to the surface. Lightning and brief period of heavy
rainfall seems to be the immediate threat through the early
night as these cells quickly track eastward over 40kts. We next
shift our attention to the MCS now exiting southeast lower
Michigan. Numerical near/short guidance has struggled all
afternoon and evening with this event. With that said, this MCS
is expected to track east-southeast and approach eastern NY
between 09-10Z per timing extrapolation. Chances for severe
weather appear lower at this time, however, cloud to ground
lightning strikes and brief heavy rainfall remain a threat.
Latest SPC SWODY1 continues with a slight risk category at this
time.
Main update was to PoP/Wx grids per upstream trends and latest
coverage across the region. Did modify dewpoints a bit per
observations and NY Mesonet (especially across the Dacks).
Prev Disc...
Potential for severe thunderstorms and locally heavy rainfall
this evening into tonight. A cold front over northern NY
expected to slow its southward progress into this evening as the
flow aloft becomes parallel to the front. Not much convective
activity is anticipated through this afternoon, with
isolated/scattered showers. There is some instability south of
the front, but there is only weak forcing at this time.
An upper level disturbance evident in water vapor imagery over
the upper Great Lakes, will move eastward through the lower
Great Lakes and Northeast this evening into tonight. This
disturbance will be the main impetus for convective initiation.
Until then, a mid level cap should hold into early this evening.
The cap will erode as the upstream shortwave moves east.
Northern fringe of an EML evident on 18Z KBUF sounding, with 4-6
km lapse rate of 6.7 degC/Km. The EML is expected to advect
eastward into eastern NY this evening, which will aid in
maintaining convection. The combination of sufficient
instability (~700-1200 J/Kg MUCAPE HREF mean) and 0-6 km wind
shear of 45-55 kt will allow for storm organization and
maintenance into the overnight hours. Still some spread with
regards to exact timing, with CAMs generally showing time frame
for most intense/widespread storms between 9 PM and 3 AM.
Main threat expected to be damaging wind gusts associated with
organized lines/bows based on CAPE/shear profile and CAMs
convective mode. Also experimental HRRR SPC neural network
showing highest probabilities for wind compared to other
hazards. Still, with EML present (possible displaced south of
main convective target area) will have to watch for isolated
marginally severe hail. Main threat area looks to be from the
far southern Adirondacks, Saratoga region and southern VT
southward where a Marginal to Slight Risk outlook from SPC
remains in place. In addition to severe potential, locally heavy
rain will occur with convective cells repeatedly moving over
the same areas in vicinity of the stalling front. PWAT anomalies
forecast from the NAEFS of +1 to +2 STDEV, so will have to
watch for some flooding of urban, poor drainage and low lying
areas and isolated flash flooding.
Storms should exit into central/eastern New England after 3 AM.
A few more showers will be possible through early Monday
morning with a possible decaying convective complex approaching
from western/central NY.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The weather should become more tranquil on Monday, as the
surface front pushes just far enough south to settle somewhere
over PA/NJ vicinity. A surface anticyclone will be building
southeast across Ontario/Quebec into upstate NY. So humidity
levels will be lower (dewpoints mainly in the 50s), with near
normal temperatures. Will maintain dry forecast through the
daylight hours.
The anticyclone is forecast to gradually shift eastward into
Quebec and northern NY Monday night, which should keep the front
positioned to our south. The flow aloft will remain northwest
though, and some sources of guidance are indicating a possible
area of showers and storms moving through areas mainly south of
I-90 Monday night. Surface based CAPE should be near zero,
although some elevated instability forecast to be present as
Showalter index falls below zero. So will mention slight/low
chance POPs with a slight chance of thunder.
On Tuesday, the old front will start lifting back northward as
a warm front in response to an amplifying pattern over the Great
Lakes and Northeast. The main question for convective potential
is if our area can get into a true warm sector by Tuesday
afternoon. There are some differences among the guidance, with
the NAM maintaining a more stable environment(near zero SBCAPE)
while the GFS indicating decent instability (100-2000 J/Kg
SBCAPE) building south/west of Albany. So will mention chance of
thunderstorms for this area although it appears a main forcing
mechanism will be lacking other than the northward advancing
warm front. Deep layer shear should be strong again (35-45 kt
from 0-6 km), so isolated severe storms cannot be ruled out
especially if sufficient instability develops in the warm
sector.
Tuesday night, a cyclone is expected to track northeast from
the central Great Lakes into southern Quebec. A trailing cold
front will be approaching from the lower Great Lakes and St.
Lawrence valley towards Wednesday morning. While the main
forcing should not arrive until Wednesday, some showers and
storms may occur in a few spots. It will be warm and humid with
lows in the upper 50s to mid 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Strong frontal boundary will be moving across the area for
Wednesday. Low-level southerly flow will allow for plenty of
moisture ahead of the front with decent instability thanks to
daytime temps warming into the low 80s. Meanwhile, 0-6 km deep
layer shear should be around 40 kts thanks to an approaching
upper level shortwave. The combination of the shear and
instability should allow for a few lines of thunderstorms, some
of which may be strong to severe, for Wed afternoon into
Wednesday evening. SPC already has the area in a Day 4 15%
severe outlook (equivalent to a slight risk).
The front will cross the area Wed night but will stall just
south/east of the area for Thursday. With the front nearby, there
will be some lingering clouds and a few showers, mainly for eastern
parts of the area. Although there briefly may be some drier air
that moves in by early Thursday, the front will be returning
back northward as a warm front by late in the day Thursday into
Friday, so dewpoints will return to the mid to upper 60s for
many areas for late in the week. With the boundary nearby, can`t
rule out the threat for some additional showers, especially
during daytime heating.
The forecast for the weekend is somewhat uncertain. Low
pressure, perhaps with some tropical characteristics, will be
meandering off the eastern seaboard. The latest guidance seems
to keep this low far enough to the east and out to sea to avoid
an impact on our weather, but it will be close enough that will
need to watch model runs closely. Otherwise, our region will be
on the northern edge of an upper level ridge over the eastern
CONUS. This will keep temps warm and dewpoints high, with valley
highs in the upper 70s to near 80 and dewpoints well into the
60s. There may be a chance for some additional showers and
thunderstorms for both Saturday and Sunday, especially for
Sunday if a northern stream boundary gets close to the area, so
will keep slight to low CHC pops in the forecast for now.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Complex forecast tonight as we continue to monitor upstream
convective trends and track evolution. Latest HRRR was leaning
toward a diminishing trend as this activity approaches our
region due to further stable atmosphere in place. We will keep
VFR/MVFR ceilings at this time. A quick glance at our 00Z
sounding depicts rather steep mid-level lapse rates but a region
of drier air above 7-8K feet. So we will refrain the mention of
thunder through the evening hours. Overnight, we will continue
with the TEMPO groups for convection with MVFR conditions.
All of this convection should slide east-southeast Monday
morning with improving conditions to VFR.
Winds will generally be west-southwest tonight with a tendency
toward west-northwest toward sunrise Monday at speeds less than
10kts. Those magnitudes continue with perhaps a few occasional
gusts from the west-northwest during the daylight hours Monday.
Outlook...
Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday: High Operational Impact. Definite SHRA...TSRA.
Wednesday Night: High Operational Impact. Likely SHRA...TSRA.
Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.
&&
.FIRE WEATHER...
A cold front moving southward across the region will bring
scattered to numerous showers and thunderstorms this evening
into tonight. Some thunderstorms could become severe with
locally heavy rainfall. Following the passage of the cold front,
dry weather briefly returns on Monday before additional rounds
of showers and thunderstorms arrive Tuesday into Wednesday.
Relative humidity values will increase to around 100 percent
tonight. Relative humidity values will drop to minimum values of
around 50 to 60 percent Monday afternoon. RH values will
increase to between 90 and 100 percent Monday night.
Winds tonight will initially be southwest then shifting the
northwest less than 10 mph. Winds on Monday through Monday night
will be northwest around 5 to 10 mph.
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop ahead of a
cold front this evening into tonight. Anomalously high moisture
values with PWATs greater than 1 STDEVs above normal coupled
with the potential for repeated rounds of thunderstorms, could
result in poor drainage flooding of urban and low lying areas as
well as the isolated flash flooding.
Drier weather is expected on Monday, followed by renewed
chances for showers and thunderstorms Tuesday into Wednesday as
a frontal system moves across the region. Additional locally
heavy rainfall will be possible.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Evbuoma/BGM/JPV
NEAR TERM...BGM/JPV
SHORT TERM...JPV
LONG TERM...Frugis
AVIATION...Main
FIRE WEATHER...Evbuoma/JPV
HYDROLOGY...Evbuoma/JPV
Area Forecast Discussion
National Weather Service Denver/Boulder CO
805 PM MDT Sun Sep 12 2021
.UPDATE...
Issued at 756 PM MDT Sun Sep 12 2021
Shower and tstm activity has ended early this evening. There
are a few weak tstms over sern WY. These could affect the nrn
border area, the next few hours, if they hold together.
Late tonight an upper level jet and cold front, will affect nrn
areas of the CWA with showers developing along the CO-WY border
area.
&&
.SHORT TERM...(This evening through Monday)
Issued at 142 PM MDT Sun Sep 12 2021
Scattered thunderstorms continue to develop over portions of the
county warning area, especially over the Palmer Divide of Douglas
and Elbert counties. There is a circulation across Northeast
Douglas county with storms developing just ahead of the
circulation. Instability still on marginal side with LAPS CAPE
values only 400-800j/kg. Expect heavy rain, gusty winds and small
hail with these storms. Could see some stronger storms over the
far northeast plains with surface dewpoints still in the 50s with
CAPE values up to 1200j/kg. Most of the showers expected to
dissipate after midnight but wouldn`t be surprised to see a few
lingering showers especially with approaching jet streak over the
mountains.
For Monday, approaching upper trof and surface cold front to sweep
southward over the plains Monday morning as winds increase from the
north. This may end up stabilizing storm development in the
afternoon with main focus over higher terrain of the Palmer Divide
and. Will have highest pops over higher terrain and lower pops
over plains. Temperatures will be similar to today with readings
in the 80s.
.LONG TERM...(Monday night through Sunday)
Issued at 142 PM MDT Sun Sep 12 2021
Some lingering showers may hang around late Monday evening but any
rainfall will be very light though the HRRR keeps a few strong
storms going across the northeast Colorado closest to NE/KS through
about midnight with strong and gusty winds the primary threats east
of a Sterling to Limon line. The continued convective activity
looks to be along and just north of a moisture and theta-e axis
that sets up around I-70 in eastern Colorado. On Tuesday Colorado
remains under WNW flow aloft as a very broad trough across the
northern U.S. and Canada slowly moves eastward. A surface high
across the northern plains will induce ENE upslope flow during the
afternoon hours which will increase the surface dewpoints to
around 50 degF across much of the plains, while a short wave
trough moves across the central Rockies providing some additional
instability with cold advection in the 700-500 mb layer. The
resultant instability should be 600-1200 J/kg across the plains,
with high values along the Palmer Divide. Combined with 40 kts of
flow at 500 mb a few storms could be marginally severe during the
afternoon hours across the eastern plains. For the I-25 corridor
and the mountains and foothills to the west, instability and shear
will both be weaker and less moisture to work with so any
convection should be pretty weak with just light rainfall
possible. Coverage is not expected to be that great though the
Palmer Divide should have the best chance of decent rainfall, on
the order of 1/2" in 30 min under the strongest storms. Some cold
advection at 700 mb in the WNW flow means temperatures will again
remain cool-ish at the surface, below normal for mid-September
with highs in the mid 70s across the plains. The cooler air does
not make it west of the divide however as temps should be in the
upper 60s to around 70 across the mountain valleys.
On Wednesday the 500 mb ridge builds over Colorado and the stronger
westerly flow remains to our north. PW values decrease to around
0.75" east of I-25, but under 0.25" west of the Divide (bone dry).
Without any synoptic lift and paltry moisture, our area should
remain dry. 700 mb temps warm to around +15 degC, resulting in
highs in the upper 80s across the plains with 70s in the mountain
valleys and foothills. Winds should remain pretty low across most
of the area other than the far eastern plains and North Park
where they could gust to 20 mph.
For Thursday and Friday the ridge shifts to our south and Colorado
is under warm and dry WSW flow aloft. Our area will continue to be
dry and temperatures should top out right at or just shy of 90
degrees across the plains both days. The mountain valleys and
foothills should be in the 70s.
This weekend models begin to diverge on the overall pattern. The
EC and ensembles keep the ridge in place just to our south and
elongated west-to east cutting off any sub-tropical moisture.
Under that scenario, including nearly all the ensemble members,
our area would remain dry and temperatures would be in the upper
80s to near 90 both days. With the GFS and ensembles, things are a
little murkier. About 1/5 of the GFS ensemble members have the
ridge far enough east that some sub-tropical moisture works into
the western half of Colorado from the southwest around the
periphery of the high. Isolated thunderstorms would be possible
Sunday afternoon along and west of the Divide. However, even in
those scenarios the plains would remain too dry for any
convection. The Canadian ensembles are similar to GEFS. Thus, at
this point we`ll keep everything dry and there is high confidence
in a continuation of warm temperatures, very near or at 90 degrees
across the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 756 PM MDT Sun Sep 12 2021
VFR conditions expected the rest of tonight. Winds will gradually
become more southerly before midnight. A cold front will move
across the area by 15z on Mon with gusty north winds behind the
front.
&&
.HYDROLOGY...
Issued at 142 PM MDT Sun Sep 12 2021
Scattered showers and storms expected for the rest of this
afternoon and evening, and again from late Monday morning through
the evening. Flash flood threat still on the low side as storms
will be moving at a good clip and overall instability is limited
with mainly light to moderate rainfall expected. Passing showers
expected to drop less than a quarter of an inch in less than an
hour.
There is still quite a bit of moisture around on Tuesday, mainly
across the plains where a few strong thunderstorms could be capable
of dropping an inch of rain in less than an hour. They will be
moving east at about 35 mph so we do not expect any flooding
issues. Wednesday through Sunday looks to be dry across the entire
area.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...Schlatter
AVIATION...RPK
HYDROLOGY...Entrekin/Schlatter
Area Forecast Discussion
National Weather Service Buffalo NY
1202 AM EDT Mon Sep 13 2021
.SYNOPSIS...
A cold front dropping across the region will support showers and
scattered thunderstorms. Some of the thunderstorms could produce
strong winds and heavy rainfall. Unsettled weather will continue
through the middle of next week with possible showers and
thunderstorms.
&&
.NEAR TERM /THROUGH TODAY/...
...Severe thunderstorms early in the overnight WNY to Finger Lakes...
MCV with potential for damaging winds is arriving over WNY. 00z
soundings from KBUF and KDTX continue to show the very
favorable environment with elevated mixed layer. Low-mid level
shear, 0-1km, very strong with 30+ kts so expect this complex
to persist as cold pool shear/balance is more than ideal. Main
severe weather threat will be damaging straight line winds, but
there should be intense downpours and frequent lightning under
the cores as they move through. Based on radar trends and latest
HRRR run which is doing very well attm, expect the complex to
track just south of east at 60 mph across Southern Tier to
Finger Lakes.
Convection will diminish late tonight as the shortwave (MCV in this
case) will push east. Additional convection developing west of Long
Point Ontario will also move over western NY overnight even behind
the initial MCV. Some partial clearing could bring some fog
especially to areas that receive rain.
Frontal boundary does look to sneak south of the area briefly on
Monday, but will start to work back north as a warm front Monday
afternoon. Shortwave pushing across the area will trigger some
scattered convection along the frontal boundary late in the day.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
A stationary front will be oriented northwest to southeast from
northern Michigan to northwest Pennsylvania Monday night. Surface
high pressure will be inching into the North Country resulting in
dry conditions from the Finger Lakes into the North Country. A weak
impulse is forecast to ride along the front further west and showers
with a slight chance of thunderstorms are possible across far
western NY including the western Southern Tier. Overnight lows will
range from the low 50s across the North Country to the upper 50s low
60s across western NY.
The front will move north as a warm front across western and north
central NY Tuesday. Dewpoints and mid-level moisture will increase
while surface temperatures climb to the upper 70s to low 80s.
Surface based instability will climb with strong winds in the low to
mid levels. Showers and thunderstorms will likely form by afternoon
ahead of an approaching cold front. Some storms may become strong to
severe in the afternoon into the evening. Main threats would be
strong winds and large hail. Thunderstorms will track east with a
short break before another round of showers and storms enters the
region as a cold front approaches from the west. Uncertainty exists
Tuesday night as the wind field and surface based instability
decreases ahead of the front. Warm, overnight night with lows in
the 60s.
Model guidance is in agreement that widespread showers or rain with
thunderstorms will track across the entire forecast area Wednesday
and Wednesday as the cold front tracks east. This increase in low
level convergence will initiate thunderstorm development with some
strong to severe storms. The strongest storms are expected to be
east of the forecast area however if the front slows down that could
change. Slightly cooler Wednesday with highs in the mid to upper
70s.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A sfc ridge will provide for mostly quiet weather for the first half
of the long term period. Some guidance is suggesting an upper level
trough/low over eastern PA and southern New England may cause some
showers for the area. Will need to see how the scenario evolves as
there is decent model spread still with how much of an impact these
upper level features will have. For now have high slight chance to
low chance POPs. A frontal boundary passing south across the area on
Sunday will bring a few showers and some thunderstorms. The front
will then shift back north as a warm front later on Sunday into
Monday.
Temps during the long term will be 5 to 10 degree above normal for
this period.
&&
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
Complex of thunderstorms with gusty winds and heavy rain rolls
across western NY 4z-6z. Brief IFR possible during these storms.
After the storms later tonight, expect MVFR ceilings with IFR
possible across the southern Tier. May see some fog as well if any
clearing occurs.
Outlook...
Monday and Tuesday...Mainly VFR with a chance of showers.
Wednesday...Mainly MVFR with widespread showers.
Thursday and Friday...Mainly VFR.
&&
.MARINE...
Strong thunderstorms between 04 and 08z...particularly over Lake
Erie. Mariners should be alert for special marine warnings.
High pressure centered over northern Ontario will start to pass
by the north on Monday. This will support light and variable
winds on Lake Erie and light northwesterlies on Lake Ontario.
As the area of high pressure moves east across Quebec on
Tuesday...a cold front will approach from the Upper Great lakes.
A tightening sfc gradient between the two will lead to
freshening winds on both Lakes Erie and Ontario.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...TMA
NEAR TERM...JLA/RSH/TMA
SHORT TERM...HSK
LONG TERM...SW
AVIATION...JLA/TMA
MARINE...JLA/TMA
Area Forecast Discussion
National Weather Service Cheyenne WY
535 PM MDT Sun Sep 12 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 136 PM MDT Sun Sep 12 2021
Key Messages:
1) Isolated to scattered showers and storms this afternoon to mid
evening. One or two storms could be strong to briefly severe with
gusty winds of 40-60 mph, occasional lightning, and brief moderate
rainfall. Overall impacts will be limited in scope but quick wind
gusts could occur locally from Cheyenne to Scottsbluff to Sidney
area through 10pm.
2) Another round of showers and embedded thunderstorms is likely
early Monday morning moving across the region from west to east.
Strong to severe storms are unlikely with this round but welcomed
rain will shift through. Will need to monitor Monday afternoon for
isolated strong to briefly severe storms.
3) Much cooler Tuesday behind a cold front with temperatures
staying in the 60s to near 70 degrees but isolated storms could
remain a possibility.
Weather Details: Latest water vapor and H5 RAP analysis highlight
embedded impulses in the zonal flow across south WY this
afternoon. Coupled with 25-30 knots of 0-6 km shear and 500 J/KG
of SBCAPE and steep-low level lapse rates plus some upslope flow
across the high plains, showers and weak storms have begun to
develop. Inverted V soundings are in place again like yesterday
but DCAPE values are lower today (500-900 J/KG) vs. yesterday
(1500 J/Kg) and this should reduce the overall wind gust
potential. That stated, local wind gusts of 40-60 mph could still
be possible in downbursts from the showers and storms as they
shift across the I-80 corridor. Storm will shift quickly east in
the faster zonal flow and exit Wyoming by 8pm and end across the
NE Panhandle through 10-11pm tonight.
However, fast on it`s heels will be another more potent shortwave
trough and lifting mechanism currently over OR. This feature will
shift across WY early Monday morning and with PWATS remaining 0.7
to 1" west to east, multi-model guidance suggest solid potential
for rain showers with embedded thunderstorms being likely. Will
start west near Rawlins after 4am Monday morning and work east to
the NE/WY border by 7am and then NE Panhandle through the mid
morning hours as it becomes less organized. Greatest amount of
rain appears to be focused in Carbon and Albany Counties as it
wanes in strength farther east into the morning hours. No major
impacts expected but will need to monitor the Mullen Burn Scar if
some heavier rainfall rates or training occurs. Depending on how
fast this complex clears the region, will need to monitor for
strong storm potential to refire Monday afternoon. Lot of factors
of recovery and amount of instability will go into this possible
second round so stay tuned for future updates. Several global and
hi-res models do suggest the potential for additional storms
Monday afternoon.
Deeper NW flow will occur Monday night into Tuesday and shift
cooler H7 temperatures into the region through the day. A few
light showers possible across NE Panhandle early Tuesday morning
and will monitor for isolated storms Tuesday afternoon along the
front near the WY/CO border. Confidence is low on this storm
placement and timing so stay tuned.
.LONG TERM...(Wednesday through Saturday)
Issued at 301 AM MDT Sun Sep 12 2021
This part of the forecast will be dry despite a couple upper level
short wave troughs moving close to the forecast area.
This period of the forecast starts out with zonal upper level flow
over the northern CONUS. Models quickly fall out of agreement by
Thursday. The GFS has a trough moving off the west coast toward the
forecast area, while the ECMWF continues with the zonal flow. By
the weekend the two models are back in agreement for the most part.
The GFS has the trough absorbed into the strengthening ridge. The
ECMWF has the ridge centered more over the Mississippi River valley
instead of the High Plains like the GFS.
Given the rather zonal look of the upper level flow, and the
disagreement in the model data regarding what happens to the trough
as it approaches the forecast area, a dry forecast seems reasonable.
Highs will be fairly consistent during this period of the forecast.
The coolest highs will be Thursday as a weak cold front may move
into the northern part of the forecast area with the short wave
trough. Lows will be coolest Thursday night as a weak upper level
short wave trough moves through, bringing in a reinforcing shot of
cooler air.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 512 PM MDT Sun Sep 12 2021
Expect VFR through the evening hours at all terminals. An isolated
shower or thunderstorm can not be ruled at SNY through 2z. Skies
will generally clear until after 6z when clouds will increase from
the west. A weak wave will bring some scattered shower activity to
most terminals through the early morning hours on Monday.
&&
.FIRE WEATHER...
Issued at 136 PM MDT Sun Sep 12 2021
Elevated fire weather conditions this afternoon across Converse to
Niobrara and into the Nebraska Panhandle as relative humidity values
fall into the 20 to 30 percentiles and some wind gusts of 20 mph.
Humidity will recover well tonight into the 70-80 percentile but
winds will stay elevated near 20 to 25 mph overnight.
Limited fire weather concerns Monday with wetting rain chances
across the entire region, especially west and central locations
in southeast Wyoming. Cooler conditions Tuesday and then a
return to near-critical to critical fire weather concerns
mid to late week as temperatures warm and atmosphere becomes
quite dry.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...JSA
LONG TERM...JTL
AVIATION...MAC
FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Green Bay WI
602 PM CDT Sun Sep 12 2021
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Monday
Issued at 228 PM CDT Sun Sep 12 2021
The latest RAP analysis and satellite/radar imagery show a weak
shortwave impulse moving across southern Minnesota early this
afternoon. Areas of rain are accompanying this shortwave which are
tracking north of a stalled surface front across far southern
Wisconsin. The closest lightning detected so far has occurred over
Sheboygan County and central Lake Michigan. This light rain will
likely impact areas south of Rhinelander and Iron Mountain this
afternoon before exiting by early this evening. Timing the rain
this afternoon, and also on Monday as the front returns north is
the focus of this forecast.
Tonight...Short range guidance continues to point towards the
light rain exiting by early this evening. Relatively quick forward
motion suggests this remains possible, so will stick with
continuity. The front is expected to push into northern Illinois
and a little farther south from the area. This should keep the
chance of rain south of Oshkosh and Manitowoc, while allowing
drier air to push in from the north. The combo of light winds and
clearing skies should lead to a decent setup for ground fog
across the northwoods. Cooler lows ranging from the low 40s north
to mid 50s south.
Monday...As another shortwave impulse moves across the northern
Plains, strengthening return flow will increase through the day
which will cause the front to get pushed northward. The morning
continues to look dry at most locations. But with further
northward advancement of the front, the chance of showers and
thunderstorms will increase in the afternoon, generally south of
highway 29. Models disagree regarding the amount of instability
which moves in the far south in the afternoon. Regardless, the
instability looks elevated due to capping around 5000 ft agl.
Mid-level lapse rates of 6.0 to 6.5 C/km are also not particularly
impressive so the risk of severe weather looks low. Highs will be
mainly in the low 70s.
.LONG TERM...Monday Night Through Sunday
Issued at 228 PM CDT Sun Sep 12 2021
A warm front will lift north Monday night, as low pressure moves
into north central WI and the Upper Peninsula. Showers and
thunderstorms will increase as a 40-45 knot low-level jet and a
negatively-tilted short-wave trough take aim on the forecast area.
Deep layer shear is quite strong (40-50 knots), but instability
is mainly elevated and probably too marginal (850 mb LI`s of -1
to -3 C) to support a widespread severe threat. Heavy rainfall
will be a significant concern, as PWATs increase to 1.5-1.7 inches
across the forecast area. Localized urban flooding will be
possible. A cold front will sweep through the area late Monday
night into Tuesday, and bring a continued chance of showers and
storms through midday.
High pressure should bring mainly dry conditions Tuesday night
through Wednesday night, along with near normal temperatures.
The forecast becomes much more muddled after Thursday. The ECMWF
brings a cold front through Thursday night into early Friday, and
again Sunday night. However, the GFS is much slower, and holds off
the initial frontal passage until late Friday night and Saturday.
It appears there will be a couple periods of thunderstorms for
the end of the work week and weekend, but confidence in timing is
very low. Given the uncertainty, have not made any adjustments to
the blended pops, which have slight chance to chance pops through
most of the period. Temperatures are expected to trend above
normal during this period.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 602 PM CDT Sun Sep 12 2021
VFR conditions are expected through much of this TAF issuance. The
exception will be across RHI and possibly into AUW/CWA where some
ground fog may briefly form overnight. The next chance of showers
and thunderstorms will arrive late Monday afternoon and especially
into Monday night.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Wichita KS
954 PM CDT Sun Sep 12 2021
...Evening Mesoscale Update...
.MESOSCALE DISCUSSION...
Issued at 953 PM CDT Sun Sep 12 2021
As of 03z/10pm, regional radar reveals a small cluster of
thunderstorms moving off the High Plains of western Kansas. Based on
recent RAP data, the downstream airmass (across central KS) features
strong inhibition and relatively dry air aloft. The dry air aloft
may even be further enhanced as a developing southwesterly LLJ leads
to further downslope drying aloft. Despite the likely ongoing
development of an MCV and locally enhanced lift, there appears to be
too many limiting factors to allow the ongoing convection to survive
as it moves east into north-central KS. That said, there could be
just enough moistening aloft to support some very high-based,
weakening showers/virga with a lightning strike or two. Given the
limiting factors mentioned above, though, I`ll keep the current dry
forecast as-is, but there`s at least a conditional threat for a few
showers to clip the I-70 corridor overnight.
Martin
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 331 PM CDT Sun Sep 12 2021
A stalled frontal boundary across the Central High Plains is progged
to remain nearly stationary or begin to drift back northward
slightly as we move through the overnight and early morning hours on
Monday before returning southward with varying solutions Monday
night into Tuesday.
Mon-Tue...this frontal boundary may become a focus for deep moist
convection as we move into Tue and Tue night as a subtle shortwave
trough approaches, but may remain too far north for appreciable
storm chances on Mon-Mon night. As the mid/upper ridge continues to
dampen, we`ll see a decrease in thickness supporting slightly lower
maximum temperatures compared to the past several days however we
expect to remain well above normal at most locations with mid 90s
anticipated on Monday and a wide range of temperatures on Tue with
mid/upper 80s along the I-70 corridor and low/mid 90s along the OK
state line.
Wed...Depending on the timing of the front, we may see another round
of storms develop on Wed afternoon or with a slower solution
verifying we could just see some lingering storms through the
morning hours with clearing by afternoon. More seasonable
temperatures are anticipated with highs in the low to mid 80s
areawide.
.LONG TERM...(Thursday through Sunday)
Issued at 331 PM CDT Sun Sep 12 2021
Dry and mild conditions will develop as we move through the
remainder of the week and into the weekend when above normal
temperatures are expected to return to the area. The large-scale
pattern will feature a flat zonal flow becoming southwesterly as
we move through the period. This may result in a subtle increase
in low level moisture or higher dewpoints but the better quality
moisture is likely to be steered east of the forecast area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 650 PM CDT Sun Sep 12 2021
* Impacts from gusty winds and LLWS through Monday
* VFR conditions expected over the next 24 hours
A stationary front, currently draped from KDDC to KTOP, will meander
around the I-70 corridor tonight before lifting north on Monday. For
KRSL, the wind direction is less certain and may fluctuate more than
forecast until the front moves north. Elsewhere, a modest, and
gusty, south wind looks to prevail through Monday. As winds aloft
increase tonight, there will be an increased risk of LLWS impacts.
At this time, I do not expect the TSRA, currently over eastern
Colorado, to make it into central Kansas tonight due to weaker
instability and drier air in place. It does, however, look like
there will be an increased risk of TSRA on TUE across parts of the
area.
Martin
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 69 95 69 90 / 0 0 0 30
Hutchinson 69 95 68 88 / 0 0 10 30
Newton 68 93 69 87 / 0 0 0 30
ElDorado 67 93 69 88 / 0 0 0 30
Winfield-KWLD 67 94 69 91 / 0 0 0 20
Russell 68 97 66 85 / 10 10 10 30
Great Bend 69 98 66 85 / 10 0 10 30
Salina 70 94 69 86 / 0 10 10 30
McPherson 69 94 67 86 / 0 0 10 30
Coffeyville 65 93 70 90 / 0 0 0 20
Chanute 65 92 71 88 / 0 0 0 30
Iola 65 91 70 87 / 0 0 0 30
Parsons-KPPF 64 93 70 90 / 0 0 0 20
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
MESOSCALE...RM
SHORT TERM...MWM
LONG TERM...MWM
AVIATION...RM
Area Forecast Discussion
National Weather Service Indianapolis IN
1136 PM EDT Sun Sep 12 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 939 PM EDT Sun Sep 12 2021
Surface analysis this evening shows a progressive westerly flow in
place across Indiana amid a tight pressure gradient. A frontal
boundary was found over the Great Lakes while high pressure was
found across the southeastern states. A nearly zonal flow was in
place aloft. This along with the strong surface high was preventing
the cold front from making any progress southward. GOES16 shows
clear skies across the forecast area. Dew points were still in the
60s.
Little overall change is expected overnight as the zonal flow and
relatively tight pressure gradient remain in place. This should just
result in some passing high clouds...mainly across the northern
parts of the forecast area. Decent mixing overnight should help keep
temperatures from falling too much. Forecast soundings and time
heights continue to show a dry column. Thus will trend toward a
mostly clear sky and low temps near persistence. Overall...ongoing
forecast appears in good shape.
&&
.Short Term...(This evening through Monday night)
Issued at 301 PM EDT Sun Sep 12 2021
High pressure continues over the southeast U.S., with a pressure
gradient over central Indiana that is allowing southwesterly winds
to gust to around 30 mph. Gusts should lessen over the next few
hours and drop off with sunset.
Some high clouds could continue to spill over the ridge, but not
much. Skies will continue to look a little milky though, through the
night and tomorrow with smoke from wildfires continuing to hang
around overhead with the HRRR smoke showing this well.
By Monday night, should see the clouds start to move into northern
counties as the front to the north produces more convection and the
clouds spill into the area.
As far as temperatures are concerned, the warmth will continue and
humidity will increase with the southwesterly flow in place.
&&
.Long Term...(Tuesday through Sunday)
Issued at 301 PM EDT Sun Sep 12 2021
The long term period will start out warm ahead of an approaching
trough and associated cold front. The cold front will finally push
southward across the region as the ridge weakens after having been
stalled to the north for several days. It is expected to bring
showers and storms to central Indiana from Tuesday evening to
Wednesday night. Models are currently suggesting that a line of
storms will organize along the front as it approaches the forecast
area during the latter half of the day Tuesday. But where could also
be isolated to scattered showers forming ahead of the front due to
weak isentropic lift. A few storms could be strong to severe with
the instability and potential shear that could come along with this
system late Tuesday and possibly into Wednesday, but the specifics
are still not clear at this time.
Models get nosier beyond the frontal passage but tend to generally
agree on ridging and subsidence providing a good chance of quiet,
although warm, weather this weekend. Confidence is low for
precipitation chances late this work week and will depend on how the
the front evolves midweek, so will keep the low PoPs for Thursday
and again Friday afternoon. A bit more confidence comes with the
temperatures which will briefly cool down to near normal behind the
front. Temperatures will then quickly rebound to above normal for
the remainder of the long term as SW flow returns to the area.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1136 PM EDT Sun Sep 12 2021
IMPACTS:
- VFR Conditions are expected this Taf period.
- Southwesterly surface winds near 6-10 knts will be expected during
this period.
DISCUSSION:
Little overall change from the previous TAF issuance. A moderate
pressure gradient will remain across Central Indiana tonight and
into Monday...keeping winds around 10 knts through the period.
With the continued influence of high pressure, mainly some passing
high clouds expected during the period. Forecast soundings and time
height continue to show a very dry column with unreachable
convective temperatures.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...CP
Long Term...KH
Aviation...JP
Area Forecast Discussion
National Weather Service Louisville KY
725 PM EDT Sun Sep 12 2021
...Updated Aviation Discussion...
.Short Term...(This evening through Monday)
Issued at 240 PM EDT Sun Sep 12 2021
The center of a strong (594 dam) 500 mb ridge over the region this
afternoon will shift east of the area on Monday. Sfc high pressure
over the Southeast US will remain in place and gradually weaken
through Monday, allowing the pressure gradient to relax across
central KY and southern IN. The synoptic pattern will continue to
support warm, moist SW flow through tomorrow with sfc dewpoints in
the mid/upper 60s.
This afternoon, skies are mainly sunny with just a shallow cu field
over south-central KY. Skies are somewhat hazy, however, due to
elevated concentrations of smoke higher in the atmosphere. The HRRR
suggests decreasing vertically integrated smoke on Monday.
Temperatures are in the low to mid 80s as of this writing, so most
areas should at least max out in the mid 80s. SW winds will remain
gusty through sunset before diminishing somewhat. Continued SW flow
and a relatively humid airmass will keep overnight lows in the
mid/upper 60s.
Model RH time heights and HREF guidance suggest a broader SCT cu
field across the region Monday afternoon. Temperatures will again
push into the mid/upper 80s in most areas with a few spots near 90.
.Long Term...(Monday night through Sunday)
Issued at 245 PM EDT Sun Sep 12 2021
East-west ridging aloft will be in place for most of the week, with
the westerlies largely remaining to our north. This pattern does
break down briefly on Wednesday as a progressive shortwave trof
swings through the Great Lakes, pushing a weak cold front into the
Ohio Valley. Will carry a likely POP on Wednesday, as it seems a
good bet for most of the area to at least get measurable precip. Not
expecting much organization given relative lack of instability and
shear.
Confidence diminishes late in the week as the front washes out, and
questions abound as to the moisture plume from Nicholas. Euro is
more bullish than GFS in pulling tropical moisture northward into
the Ohio Valley, but either way it`s still a warm and muggy air
mass. In the absence of any significant lift, will look for
scattered afternoon convection each day.
Temps will run slightly above climo through the period, especially
at night given the moist air mass. Main bust potential exists with
max temps if any day gets to be more convectively active.
&&
.Aviation...(00Z TAF Issuance)
Issued at 725 PM EDT Sun Sep 12 2021
VFR conditions are expected through the forecast period. Expect
mostly clear skies to remain overnight as south winds weaken.
Tomorrow, scattered cu will blanket the region as southerly winds
increase to 5 to 10 knots.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Short Term...EBW
Long Term...RAS
Aviation...KDW
Area Forecast Discussion
National Weather Service Marquette MI
629 PM EDT Sun Sep 12 2021
.SHORT TERM...(This evening through Monday)
Issued at 356 PM EDT SUN SEP 12 2021
Water vapor imagery and RAP analysis show that the vigorous
shortwave that was over northern MT/sw Saskatchewan 24hrs ago has
moved e, almost to Lake Superior, but it has weakened considerably
due to moving into a more confluent flow regime over the northern
Great Lakes. With its weakened state and with plenty of dry air
noted below 650mb on the upstream 12Z KINL sounding (dwpt depression
as high as 40C around 795mb), this wave is not producing any pcpn in
its vcnty. The cold front that passed across Upper MI yesterday
currently extends from IA to southern Lwr MI. Shra have been
occurring along and n of the front, but all the pcpn has remained s
of Upper MI today. There may have been a few sprinkles across
southern Menominee County in the last few hrs, but the AWOS did not
indicate any, and cloud bases were aoa 10kft. Under a mix of clouds
and sun, temps currently range thru the 60s F across the fcst area.
Quiet weather will prevail tonight/Mon. Another weak shortwave is
fcst to streak across the area tonight. It won`t produce anything
more than some patchy mid cloudiness. Then on Mon, shortwave ridging
will reach Upper MI ahead of a stronger shortwave moving across the
Dakotas to MN by evening. Thus, dry weather will continue on Mon. At
the sfc, high pres ridge extending s thru Manitoba to the eastern
Dakotas/western MN will shift e, reaching the fcst area tonight then
drifting e of the area on Mon. Under the ridge, expect calm/near
calm winds tonight. Given what should be a mostly clear night,
favored the low side of guidance for min temps. Column won`t be much
drier than normal to really enhance radiational cooling tonight as
precipitable water values will be right around normal for this time
of year. Thus, didn`t opt to drop mins further than the low side of
guidance. Expect min temps from the upper 30s across the interior w
ranging up to the upper 40s/lower 50s F near the Great Lakes shores.
A few of the traditional interior cold spots across the interior
west half may slip toward 35F. With a quiet/cool night and likely
sufficient lack of cloud cover, some ground fog should develop
around rivers/streams/lakes/swampy areas, typical of this time of
year. In addition, with low-level e to se flow developing across
Lake MI, stratus may develop overnight into s central Upper MI as
the lake modified air overrides the radiationally cooled air over
the land. Would like to see sfc winds take on a more decidedly e to
se direction over the land for more certainty on that potential.
With the lake modified air then advecting nw on Mon, it should
result in sct to bkn cu/stratocu development into portions of
central Upper MI. Expect high temps on Mon generally in the mid 60s
to lwr 70s F, coolest across Keweenaw County.
.LONG TERM...(Monday night through Sunday)
Issued at 349 PM EDT SUN SEP 12 2021
The extended period should start out pretty active, with a shortwave
moving into and through the area Monday night and Tuesday. Thinking
rainfall is going to begin over the U.P. around midnight central
time (give or take an hour or two). We could see some heavy rainfall
across the area Monday night and Tuesday, as most model guidance has
the sfc low of the shortwave moving directly over us. If this model
solution comes true, we could see a soaking rainfall event across
much of the interior areas of the U.P., which would be a much
welcome help in alleviating drought concerns. Don`t think that there
will be any flash flooding concerns, but wouldn`t be surprised if
some ponding occurred in areas where it typically happens (Lincoln
Ave in Escanaba for example). However, there are some doubts in
regards to U.P. receiving a soaking rainfall event (or at the very
least the Keweenaw); the NAM suite of models, as well as the NAEFS
ensemble, seems to hint at the greatest rainfall amounts occurring
south of us in WI Monday night. Should this suite of model solutions
(which is in the minority) come true, then the west (especially the
Keweenaw) may only see some light rainfall; there is a small
possibility that the Keweenaw could escape having rainfall
altogether. Hoping this solution doesn`t come true, but given the
history of shortwave lows tracking just south of us along the WI
border, I could definitely see this come to pass. Ultimately,
leaning towards the former set of solutions in my forecast, but to
reiterate, there is a chance that we lose out on the heavy rainfall
in the west (especially the Keweenaw) if the NAM/NAEFS solutions
come to pass.
Behind this shortwave, expect ridging to move back over us for a
short while during the middle of the week. Expect the coolest temps
to get down to the mid 40s over the interior west Tuesday night. On
Wednesday, we should see highs in the upper 60s to low 70s across
the area. We should start to see WAA move back over the U.P.
Wednesday afternoon as another troughing pattern moves towards us
from the west. Overall, expect pleasant weather for the mid week
ahead of the troughing pattern.
The troughing pattern should stall out right over us Thursday. This
should allow warmer temps aloft to remain over us until Friday at
the very least. The best forcing looks to remain west of us near the
Arrowhead region Thursday, although we may see a a couple of showers
and a thunderstorm or two over the far west late in the day as a
shortwave rides the troughing gradient from the Northern Plains
towards us. It looks like we could see a couple of shortwaves move
over us late this week and this upcoming weekend. Probably will see
the better rainfall amounts over the western portions of the CWA
with the first (aforementioned) shortwave as it moves northeast over
western Lake Superior. Thinking a weaker second shortwave will move
over the central and east as the troughing erodes late this week and
gives way to weak ridging again.
Expect temperatures to really warm late in the extended period (see
the ENS and NAEFS ensembles) as yet another low pressure brings a
troughing pattern to the west of us. Wouldn`t be surprised to see
some spots reach and pass 80F for high temps come next Sunday. May
see some limited rainfall this upcoming weekend (depending on which
model guidance you want to believe); otherwise, thinking we will
mostly dry this upcoming weekend, particularly Sunday since model
guidance was showing troughing west of us then.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 629 PM EDT SUN SEP 12 2021
VFR conditions will prevail at all sites this fcst period. However,
there will be the potential of shallow radiation fog to develop
overnight at any of the terminals. Right now, KSAW probably has the
best chance of seeing some fog. Included an IFR vis late tonight,
but could certainly be IFR or even LIFR if clear skies dominate
tonight, allowing for thicker fog development.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 356 PM EDT SUN SEP 12 2021
With high pres ridge building over the area, winds will be mostly
under 15kt into at least Mon morning. Winds will then begin to
increase Mon aftn as the next low pres trough approaches. That
trough will cross Lake Superior on Tue. SE wind gusts ahead of the
trough may reach 25-30kt Mon night/Tue morning, maybe locally
higher, and that will depend on a potential low pres wave that may
develop on the trough and track ne across eastern Lake Superior.
Could be a brief period of equally strong nw winds in the immediate
wake of the low on Tue, if the low develops. Winds will then
diminish to under 15kt from w to e into Wed as high pres moves e to
the Great Lakes. Southerly winds will then increase later Wed
night/Thu ahead of the next low pres trough that will reach Lake
Superior Thu night. Would not be surprised to see 30kt gusts develop
ahead of the trough, especially across the e half of Lake Superior.
Winds will then diminish on Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...07
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
632 PM CDT Sun Sep 12 2021
.UPDATE...
Issued at 632 PM CDT Sun Sep 12 2021
The AVIATION section has been updated for the 00Z TAF issuance.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 213 PM CDT Sun Sep 12 2021
Not much change from midday update. HRRR guidance suggests that
elevated smoke layer will dissipate tonight and overnight.
The leading edge of a moisture plume moving into the Lower
Mississippi Valley ahead of the very slow moving Tropical Storm
Nicholas early this week will move into parts of southeast MO and
the Purchase area of west Kentucky Tuesday afternoon. However,
during the transition, temperatures will raise slightly higher in
the absence of elevate smoke layer. Lapse rates in the 0-3km layer
and mid-level (700-500 mb) are support of aiding surface based
buoyancy of air parcels for brief isolated convection Tuesday
afternoon.
NBM initialization for Tuesday evening PoPS/Weather is acceptable,
mainly due to ageostrophic flow and marginal lapse rates for
convection in vicinity of the approaching frontal zone and
elevated lift.
.LONG TERM...(Wednesday through Sunday)
Issued at 213 PM CDT Sun Sep 12 2021
For Wednesday, model guidance has been across the board on degree
of forcing and lift with the frontal zone draped across the area
Wednesday, but weakening and becoming more diffuse Wednesday
Night. The trend in the model guidance has been to increase PoPs
significantly into the likely category on Wednesday. However,
looking at the 0-3km/3-6km/500-700 mb lapse rates and wind shear,
both are very marginal for sustained convection and higher QPF.
Decided to reduce coverage of likely PoPs and favor more areas of
chance PoPs on Wednesday, owing to pockets of higher instability
and lift along the decaying frontal zone.
The ECMWF and Canadian have different mesoscale/sub-synoptic waves
moving in the vicinity of the ridge on Thursday. Given the
variability of the lifting mechanism (distance/intensity of wave
in the vicinity of WFO PAH) kept close to the NBM chance PoPs on
Thursday and again during the daytime hours on Friday and
Saturday. Confidence is somewhat lower during this forecast period
given the faster zonal flow across the northern 1/3 of the nation
an the weaker flow in the southern 1/3 to 2/3rds of the nation.
Being on the edge of this transition zone does not support a high
PoP forecast at this juncture. Associated nearby cloud cover
should keep temperatures muted by at least 1-2 degrees from normal
this time of year.
&&
.AVIATION...
Issued at 632 PM CDT Sun Sep 12 2021
The TAFs are VFR. The only threat to VFR will be fog at KCGI late
tonight. Guidance is hitting it pretty hard, but we should have
enough wind to keep it from developing. A few southerly gusts
15-20kts will be possible throughout the region Monday afternoon.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...DRS
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...DRS
Area Forecast Discussion
National Weather Service Mount Holly NJ
903 PM EDT Sun Sep 12 2021
.SYNOPSIS...
High pressure will continue to sit to our south tonight into Monday.
A cold front will move south into the region late Monday into Monday
night before pushing back north as a warm front on Tuesday.
Another cold front will approach the region Wednesday, then move
through on Wednesday night into Thursday before stalling nearby.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 900 PM, a cold front was draped from New England to
Western New York then back across southern Lower Michigan. Some
patches of mostly high level cloud will move through our region
tonight in the mostly zonal flow aloft. Significant convection
is ongoing from Lower Michigan toward western New York. This is
associated with an MCV embedded within 60-knot mid level flow.
This activity is anticipated to remain north of our region
through the overnight given the more zonal flow and the
positioning of the cold front. Just some cloud debris spilling
into at least the northern areas overnight associated with that
convection is expected. Just made some tweaks to the hourly
temperature, dew point, wind and sky grids to keep them current
with the latest observations and trends.
Otherwise, the cold front will continue to slowly settle towards our
area but based on the latest guidance, it may not even reach our
northern areas until Monday morning. There will likely be a slight
southward push of the front through midday Monday before it finally
starts to push further south Monday afternoon/evening. Flow aloft
remains zonal, keeping the front from moving at any appreciable
speed but with some mid level shortwaves move through the region as
we head into Monday afternoon, there will be the chance for some
isolated showers or thunderstorms, mainly confined to the I-78
corridor and north. Confidence is still pretty low that we will see
much in the way of any precipitation before later Monday.
Overall, tonight will be on the warm side as the southwest flow
continues to pull warm and moist air into the region. Overnight lows
will likely range from the mid 60s to lower 70s across the forecast
area. The southwest/west flow won`t let up on Monday and once again
we feel like we have jumped right back into summer instead of
heading towards fall. With 850 mb temperatures around 16-18C, we
should expect highs to rise into the mid 80s to lower 90s. However,
with the front starting to drop south into the region, it will be a
tough call as to exactly where the temperatures start to drop off as
increased cloud cover and more northerly flow will exist closer to
the boundary. Expect areas in the southern Poconos and northern New
Jersey will be the coolest with highs only reaching into the mid 70s
to low 80s.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
The main highlights for this period are the threat of severe weather
Monday night and the continuing trend of very warm and humid weather
through midweek.
To begin the period Monday evening, a cold front will be draped west
to east across NE PA into northern NJ. Forecast models continue to
suggest that some convection may fire along this front Monday
evening but with the limiting factors being a capping inversion just
below 700 mb with a dry layer above this level. However there will
be a shortwave moving through during the 0-6z period and this may be
enough to trigger at least some scattered storms. Deep layer shear
will be strong, around 40+ knots, with steep L57 lapse rates. So if
storms do manage to get going they could become organized and grow
upscale into a line, cluster or line segments that would then
propagate E/SE. Not surprisingly, forecast models not in good
agreement with the ARW being most aggressive for the area while
the HRRR develops a strong MCS but has it farther north over SE
NY into southern New England. This all said, overall severe
weather threat appears to have increased and the SPC has now
upgraded portions of NE PA into northern NJ (basically north of
the I-78 corridor) to a SLIGHT risk for severe weather with the
MARGINAL risk now extending roughly as far south as Philly to
ACY. Main threat looks to be damaging winds.
The aformentioned front may briefly make it as far south as SE
PA into southern NJ early Tuesday before then lifting back to
the north through the day Tuesday as a warm front. This overall
set up will result in conditions being several degrees cooler
(compared to Monday) for portions of northern NJ with also more
in the way of cloud cover here as well as a frontal inversion
may set up with some low strato cu. Farther south it will still
be another very warm, humid day with highs mostly in the upper
80s to near 90 over SE PA into southern NJ and Delmarva except
cooler near the coast. In the upper levels, ridge crest will be
building near the coast so convective threat looks fairly muted
but there still could be a few scattered storms...mainly N/W of
the I-95 corridor.
Tuesday night into Wednesday, a low pressure system will be moving
eastward through northern Quebec and this will eventually drag
a cold front towards the region by late day. However ahead of
this front, SW flow will bring more widespread very warm to hot
and humid conditions with highs once again in the 80s to near 90
for many areas of the CWA (except about 5 to 10 degrees cooler
over the southern Poconos and near the coast). Also, as the
front approaches from the north and west, showers and
thunderstorms are likely to develop over central PA into
upstate NY and start to affect the region by the late afternoon
/ early evening time frame as they move east. Once again, severe
weather will be possible as ML CAPE looks to be potentially
maxing out around 1000 j/kg with a belt of mid level winds in
the 35 to 45 knot range. Best chance for storms and severe
weather through the early evening looks to be N/W of the I-95
corridor.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The general trend is for it to be wetter and unsettled for the end
of the week, possibly lasting into next weekend, but there remains a
lot of forecast uncertainty at this time. The main weather players
will be a cold front moving southward into the region along with a
pair of tropical systems to our south...one over the SE US
(Nicholas) and another one farther east over the Atlantic. There
will also be strong ridging shifting just east of Bermuda over the
Atlantic. The upshot of all this is that the cold front looks to
move south into the area Thursday and then potentially stall.
Whether the front remains active into Friday and next weekend
(possibly even drawing in tropical moisture from the south) vs.
breaking apart as high pressure tries to nose back in is the
most uncertain part of the forecast. Best chances for
showers/storms looks to be Wednesday night and Thursday where we
keep high chance POPs to low end likely POPs in the forecast.
With PWATs rising to the 1.5 to 2.0 inch range there will be a
heavy rainfall threat that will need to be monitored. As
mentioned, forecast grows more uncertain by Friday into next
weekend but it has the potential to remain unsettled so we keep
chance POPs in the forecast into next Saturday. The temperatures
will be trending a bit cooler during this period due to the
cold front and unsettled conditions but it will still remain
fairly humid.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Tonight...VFR. Southwest winds 5-10 knots, becoming locally light
and variable, then becoming west-northwest near 5 knots at some
terminals closer to daybreak. High confidence.
Monday...VFR. West-northwest winds increasing to around 10 knots
through early afternoon (a few afternoon gusts to 15-20 knots are
possible), then turning west to west-southwest by late afternoon.
Moderate confidence.
Outlook...
Monday night through Tuesday night...Mainly VFR. MVFR possible with
a few showers and thunderstorms near RDG, ABE, and the I-95
terminals. Light and variable winds Monday night, becoming
southeasterly 5-10 knots Tuesday. Low confidence regarding
shower/thunderstorm placement and timing.
Wednesday through Friday...Mainly VFR. MVFR with showers and
thunderstorms possible. South winds around 10 knots Wednesday
diminishing at night, then east-southeast winds 5-10 knots Thursday
into Friday. Low confidence regarding shower/thunderstorm placement
and timing.
&&
.MARINE...
As of 900 PM, the Small Craft Advisory has been cancelled as
the conditions have been below the criteria for quite some time
now, and the winds are not expected to increase overnight.
The conditions are therefore anticipated to remain below Small
Craft Advisory criteria through Monday.
Outlook...
Conditions will remain below SCA levels Monday night through
early Wednesday. However by late Wednesday into early Thursday
southwest winds may increase to SCA levels ahead of an
approaching cold front. These winds should then diminish for the
day Thursday into Friday as the front washes out near the area
however there will be the threat of showers and thunderstorms
over the waters by this time.
Rip Currents...
Monday...Lighter winds combined with less of a long period swell
component/energy and lower waves in the surf zone results in a
LOW risk of dangerous rip currents for both the New Jersey and
Delaware beaches.
Tuesday...Southeasterly winds increase some, however waves in the
surf zone are forecast to be low along with a lower swell component
and therefore a continued LOW rip current risk.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
Synopsis...Fitzsimmons/Meola
Near Term...Gorse/Meola
Short Term...Fitzsimmons
Long Term...Fitzsimmons
Aviation...Gorse/Kruzdlo
Marine...Fitzsimmons/Gorse/Meola
Area Forecast Discussion
National Weather Service Pocatello ID
155 PM MDT Sun Sep 12 2021
.SHORT TERM...TODAY THROUGH WEDNESDAY.
This afternoon, there is a shortwave trough that passes through
Northern Utah and brings with it showers and thunderstorms for
parts of southeast Idaho. The best chances for precipitation come
along the Utah and southern section of the Wyoming border.
Isolated thunderstorms and showers look to have more of a northern
trend over yesterdays storms, with some possible interaction up to
the Eastern Snake Plain. Chances for precipitation decrease during
the overnight hours and into the start of Monday. For Monday
afternoon, showers are expected in Wyoming with a slight chance
of some activity along the Idaho/Wyoming border. Winds remain
slightly breezy through the period, especially across the Snake
Plain with gusts up to 25mph. Current HRRR Smoke guidance brings
some smoke across the Snake Plain for Monday, with clearing
conditions expected outside of the western Central Mountains
through midweek. Temperatures remain in the 70s to low 80s, with
Wednesday looking like the warmest day of the week.
CM
.LONG TERM...WEDNESDAY NIGHT THROUGH NEXT MONDAY
Wednesday night through Friday is showing persistent dry, westerly
flow across the region with seasonable temperatures into the start
of the weekend. Gusty winds are expected Wednesday and Thursday
afternoons and evenings, due to the passage of a series of
shortwave troughs through the area. Our next best chance for
precipitation comes late Friday and into the start of the weekend,
with low confidence in the extended models of where the exact
position of the trough sets up. Timing wise for much of the
moisture has slowed down through the weekend, bringing the trough
through towards Sunday. With that possible frontal passage
through the weekend, we could see a cooling trend on the backside
of the trough with temperatures in the 60s into next week.
CM
&&
.AVIATION...
A trough is moving over northern Idaho currently. Expect breezy to
moderate winds (20 to 25 knot wind gusts) especially for KPIH, KIDA,
and KDIJ this afternoon into early evening. Vicinity thunderstorms
are possible too, especially for KPIH and KDIJ. Models are not in
completely agreement. Some models show thunderstorms to the south of
KPIH and KDIJ instead of moving over them.
Wyatt
&&
.FIRE WEATHER...
This afternoon into early evening, a trough will enhance the
moisture and instability over our southern and southeastern areas.
Expect Isolated to Widely Scattered showers and thunderstorms over
these areas this afternoon into early evening. Also, expect breezy
to moderate winds with 20 to 30 mph gusts across the area. Relative
humidity will be above critical values today except for a few valley
locations in zone 476 (Lost river area). On Monday afternoon the
Central mountains will have near critical relative humidity but
winds look relatively light, just slightly breezy, gusts of 15 to 20
mph. Wednesday into Thursday another trough moves over northern
Idaho bringing back critical winds with gusts of 25 to 30 mph.
Relative humidity will be 12 to 20 percent in the afternoon and be
slightly higher on Thursday. With drought conditions and existing
fires a red flag warning may be warranted on Wednesday, especially,
in the Central mountains and the Arco desert. Friday into Saturday
expect critical winds again but relative humidity continues to rise
with moisture starting to move into the area ahead of a potentially
wet system moving through Sunday into Monday.
Wyatt
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
855 PM MDT Sun Sep 12 2021
.UPDATE...
Issued at 848 PM MDT Sun Sep 12 2021
Updated the precipitation forecast based on the latest radar data.
Scattered thunderstorms continue over the far Eastern Plains this
evening, slowly tracking east-northeast. The strongest storms are
currently located over Prowers County and will lift into Kiowa
County through 11 PM. Storms should clear into western Kansas by
11 PM. This stronger storm may be capable of producing hail to one
inch in diameter and wind gusts over 60 mph, along with heavy
rainfall. Mozley
UPDATE Issued at 551 PM MDT Sun Sep 12 2021
Updated the precipitation chances for this evening based on the
latest radar trends across southern Colorado. A cluster of
stronger storms is currently moving east across Las Animas County.
These storms may produce gusty winds to near 50 mph and half inch
hail. More isolated, weaker showers and thunderstorms are bubbling
up along the I-25 corridor from Pueblo to Trinidad. An outflow
boundary is currently dropping south, and is currently located
north of Highway 50. This may provide the focus for additional
thunderstorm development this evening, mainly along and north of
Highway 50. Hail to near 1 inch and thunderstorm wind gusts to 60
mph may be possible through 10 PM. Mozley
&&
.SHORT TERM...(This evening through Monday)
Issued at 251 PM MDT Sun Sep 12 2021
The anticipated showers and thunderstorms this afternoon have
developed and pushed away from the mountains into parts of the I-25
corridor. The more robust thunderstorms have been across the Pikes
Peak region and El Paso county, where strongest forcing/focus has
remained. While MLCAPE has lowered today, steep mid/low level lapse
rates, this strong forcing, and increased shear has helped to offset
the lacking CAPE. The current storms moving across El Paso county,
while are on the stronger side with gusty winds and small hail
likely, should remain sub severe as they push east over the next
couple of hours.
By early this evening, focus for any additional development will
shift to the eastern plains mainly along and north of Highway 50.
Forecast soundings continue to show some really dry air in place,
that could be another limiting factor. However, surface trough and
low/mid level baroclinic zone along with an instability axis trying
to inch its way west could be enough support/focus to provide at
least an isolated storm or two. If any storm does develop this
evening, it will have the potential to become strong to severe given
the much higher shear and instability in place. Given the high temp
and dewpoint spread and latest RAP analysis showing high DCAPE in
place, the main concern will be damaging wind gusts.
Additional thunderstorms are possible Monday afternoon as surface
trough and boundary approach from the north. Highest chances for
showers and thunderstorms will once again be across the mountains,
Palmer Divide, and eastern plains along and north of HWY 50. Highest
shear and instability will also be in this location, and can`t
completely rule out some stronger development.
.LONG TERM...(Monday night through Sunday)
Issued at 251 PM MDT Sun Sep 12 2021
Tuesday still looks like the best day this week for more widespread
precipitation over the eastern plains, as the axis of a large upper-
level trough is slated to make its way through the region during the
day. By midday, the associated cold front is expected to push south
across the plains, with residual low-level moisture and post-frontal
upslope flow being more than enough to initiate widespread showers
and thunderstorms over the area. Models currently indicate a
potential for strong to severe storms later in the afternoon,
specifically over the Palmer Divide and eastern plains, with over
800 J/kg of CAPE and over 30 knots of bulk shear possible. Possible
hazards at this time include winds up to 60 mph, 1 inch hail, and
possibly an isolated tornado. Should the front stall out over the
plains, the enhanced low-level convergence will increase the chances
of severe weather occuring. Thanks to the front, Tuesday will be a
bit cooler, with highs expected in the high-70s to mid-80s over most
of the area.
Wednesday is still expected to be more of a transition day, as flow
aloft turns from northwesterly to more west-southwesterly. The flow
will generally stay dry, but the shift in direction will allow for
temperatures to increase once again, quickly climbing back into the
mid-90s over the plains by the weekend. These warming and generally
dry conditions should persist through Sunday.
With the dry air present and increased winds possible with the
incoming trough on Tuesday, spotty critical fire weather conditions
will be possible over the San Luis Valley. Additionally, the SLV,
upper Arkansas River Valley, and the I-25 corridor have a low chance
for critical fire weather conditions on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 251 PM MDT Sun Sep 12 2021
Mainly VFR conditions and dry weather expected across the TAF sites
this period, though scattered showers and even an isolated
thunderstorm will remain possible at COS. This shower/thunderstorm
possibility will continue through early this evening across COS, and
then again late Monday afternoon. Confidence is highest this
evening, and lowers for Monday afternoon. Some possibility for
precip across PUB Monday, though confidence is once again low.
&&
.CLIMATE...
Issued at 343 AM MDT Sat Sep 11 2021
Here are the record high temperatures for today and tomorrow.
Record Highs for 9/12
ALS 84 degrees set in 1990
COS 91 degrees set in 2018
PUB 97 degrees set in 2018
Record Highs for 9/13
ALS 87 degrees set in 1990
COS 94 degrees set in 1990
PUB 100 degrees set in 1990
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MOZLEY
SHORT TERM...RODRIGUEZ
LONG TERM...GARBEROGLIO
AVIATION...RODRIGUEZ
CLIMATE...GARBEROGLIO
Area Forecast Discussion
National Weather Service Reno NV
1226 PM PDT Sun Sep 12 2021
.Synopsis...
Typical autumn conditions are expected into mid week with dry and
warm days, cool nights, and occasional gusty winds. Low pressure
coming in off the Pacific Friday and into next weekend could bring
stronger winds, much cooler temperatures, and even some light
showers.
&&
.Discussion...
Rather tranquil weather for much of this coming week with warm days,
cool nights, and dry conditions. Take advantage of this for outdoor
activities and projects - I`m sure there`s some yard work with my
name on it. Westerly breezes this afternoon/evening will become
light and variable Monday-Tuesday as a shortwave trough exits the
region. A return to typical west/southwest breezes is expected
Wednesday-Thursday. At this point based on nearby fire activity and
the latest HRRR Smoke model, significant smoke is not anticipated
through at least Tuesday.
Starting Friday and into the next weekend, most ensemble members
have some flavor of trough digging into the west. This would result
in notable cooling, stronger winds, and even some light
precipitation. ECMWF EPS hitting at highest probability of stronger
winds being Friday and Saturday which could result in critical fire
weather conditions and travel impacts. Latest simulations have
trended a little wetter, especially the GFS-based models, with low-
end AR landfall signals now showing up into far N Cal next weekend.
Probabilities of any meaningful precip remain low and most of it
would be confined north of I-80, but we`ll take what we can get at
this point.
Pretty tremendous variability in the ensemble guidance for the Week
Two period - either warming back up into the 80s for W Nev or
cooling off rather dramatically with highs only in the 60s. No
appreciable precip or strong wind signals in the data in either
scenario.
-Chris
&&
.AVIATION...
Quiet weather with VFR conditions through midweek. Typical
westerly afternoon gusts around 20kt will prevail across all
terminals through early this evening.
Smoke impacts will remain confined to areas directly downwind of
the Dixie Fire into southern Oregon. Limited smoke is also coming
off the Caldor Fire.
Next weather feature of interest looks to be next weekend as a
low pressure system approaches the PacNW. Potential for stronger
winds, cooler temperatures, and possibly even some light showers
across NE California and NW Nevada. Fuentes
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Springfield MO
627 PM CDT Sun Sep 12 2021
...00Z Aviation Update...
.SHORT TERM...(This evening through Monday)
Issued at 1226 PM CDT Sun Sep 12 2021
Today is pretty similar to yesterday. Not quite as breezy and a
couple degrees cooler, but still with a hazy sky from elevated
wildfire smoke.
HRRR shows smoke concentrations decreasing and pushing north
tonight into Monday as the upper high currently just SE of the
area moves quickly east. Expect sunny skies on Monday with highs
in the upper 80s to low 90s and breezy southwest winds.
.LONG TERM...(Monday Night through Sunday)
Issued at 1226 PM CDT Sun Sep 12 2021
With a more zonal upper level flow in place, shortwave energy
will move through the central US Tuesday into Wednesday, bringing
a cold front into the area. Details of frontal timing and how far
south the front progresses are in question as models provide
varying solutions. Greatest agreement of guidance suggests the
front will move through the CWA Tuesday night into Wednesday, but
some are faster and some are slower (to the point of not even
bringing the front into the area, resulting in a much drier
forecast). If a faster timing is realized, there could be a strong
to severe storm threat over the north Tuesday afternoon/evening,
but this threat is low. The flooding threat is also low given
limited expected QPF and much of the area not seeing any precip
for over a week.
Late Tuesday through Wednesday NBM QPF probabilities:
> 0.10": 50-70%, highest north.
> 0.25": 40-60%, highest north.
> 0.50": 30-40%, highest northwest.
> 1.00": 10-20%, highest northwest.
The forecast has some low end probabilities for afternoon precip
Thursday through Sunday.
For long term temperatures, expect highs in the mid 80s to around
90 Tuesday, then cooler in the low to mid 80s Wednesday. Temps
then gradually warm back into the upper 80s to mid 90s by the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 627 PM CDT Sun Sep 12 2021
Dry and calm conditions will continue through tonight and into
Monday as an upper level ridge moves eastward and begins to
flatten. VFR conditions will be present at all TAF sites through
the TAF period. KSGF and KJLN will see winds out of the south-
southwest with gusts of 15-20 knots late Monday morning into
Monday afternoon.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Titus
LONG TERM...Titus
AVIATION...Burchfield/Langfeld