Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/02/19
Area Forecast Discussion
National Weather Service Amarillo TX
638 PM CDT Tue Oct 1 2019
Moist airmass with scattered showers and a couple thunderstorms
will continue to play havoc on aviation conditions, primarily in
the form of MVFR ceilings at all site sometime during the next 24
hours. DHT and GUY should only be dealing with restrictions for
the first few hours of the period before the mid levels dry out as
the moist axis shifts east. AMA, while initially VFR, is expected
to return to MVFR as stratus and perhaps another round of showers
expands northward overnight. Low probability of thunder at each
site precluded mentions in this TAF issuance, save for later this
evening as a storm currently between PVW and CVN skirts just to
the east of AMA.
.PREV DISCUSSION... /Issued 336 PM CDT Tue Oct 1 2019/
SHORT TERM...Tonight and Tomorrow...
Current observations show the cold front stalled across southeastern
Colorado and northwestern Kansas. Meanwhile, rain showers cover the
a majority of the Panhandles. Moisture continues to be pumped into
the West Texas as the upper level low over Idaho/Montana and high
pressure over the southeast CONUS puts the area under southwest flow
aloft. However, mid-level satellite analysis and RAP 500mb heights
reveals dry air wrapping clockwise around the upper level high and
pushing west across Texas. All the while, dry air associated with
the trough axis pushes east causing the two dry air masses to begin
pinching off the moisture source. High res models indicate the
showers will become less widespread through the afternoon hours,
with the chance for a few isolated stronger showers during the
afternoon and early evening. These isolated showers may continue on
through the early morning hours Wednesday across southeast Texas
with the current forecast keeping a 30 to 40 PoP to account for any
The stalled cold front will finally begin its push south across the
Oklahoma Panhandle Wednesday; however, models are showing this
progression to be later in the evening. This is where the forecast
for precipitation gets a bit tricky and depends on the remnants of
any outflow boundaries from today`s showers and the timing/strength
of the frontal passage. Overall, the instability along the front
will play an important role in any additional showers across the
Texas and Oklahoma Panhandles Wednesday evening. Sounding analysis
shows the front to the be shallow and weak with little instability.
The current forecast leaves a 30 PoP in for the southeast Panhandles
to include for the slight chance of storms along the cold front and
any lingering boundary from today and tonight.
Temperatures are going to struggle to reach the low 70s for a high
today across the western Panhandles due to lack of solar heating
from low clouds along with on and off rain showers cooling the air.
Areas that have had a chance to see the sun a bit today with little
to no rain have chances to see the mid to upper 80s. Low
temperatures tonight will drop into the upper 50s and lower 60s
across a majority of the western Panhandles. Temperatures Wednesday
will slightly recover to normal and slightly above normal in the
upper 70s to mid 80s with mostly cloudy skies persisting through the
LONG TERM...Tomorrow Night through Monday...
Long term forecast begins with upper ridge centered over TN, an
upper trough swinging eastward over the northern Plains, with a
second trough working into the Pacific NW. As the lead trough heads
over Ontario, cold front looks to push through the Plains and
through the Panhandles, with the latest GFS largely coming around to
the more aggressive solution seen in the last couple runs of the
EC/CMC/NAM. While 700mb moisture will be less notable than earlier
in the week, still a decent amount of moisture progged to be
available below this level, so showers and a few rumbles of thunder
are likely along the front as it pushes south during the day
Thursday. Additional showers and a few storms will also be possible
Thursday night as southwesterly flow aloft continues with the
attendant possibility of disturbances in this flow generating
upglide over the post-frontal cold dome. Considering the rainfall
earlier in the week combined with progged PWAT values around 1.5
inches, flooding may be a concern once again Thursday and Thursday
night. As for other sensible weather, Thursday should be cool thanks
to the early frontal passage and expected mostly cloudy conditions.
Tricky forecast for Friday as cross barrier flow looks to induce lee
surface troughing across E CO, leading to south-southwesterly winds
across the Panhandles by the afternoon. While operational guidance
and most GEFS members depict this occurring, still quite a bit of
moisture lingering in the mid-levels, so do not think airmass will
rapidly recover due to continued cloud cover. Still, downsloping
should allow us to get back into the 70s. Finally, cannot rule out
some additional showers and thunderstorms Friday as southwesterly
flow aloft - combined with the aforementioned moisture - continues
over the CWA.
Southeastern CONUS ridge breaks down Saturday, allowing a transition
to zonal flow aloft. GFS/EC/CMC in general agreement that the trough
that worked into the Pacific at the start of the long term forecast
will be moving downstream over the northern Plains at this time as
well. Behind this feature, cool air mass is progged to advect
southward on the eastern side of the Rockies, with most guidance
depicting this reaching the forecast area by Saturday afternoon.
With the later arrival of the cold front and less cloud cover
compared to Thursday, will not go all out on a cooler solution for
now, but this may be a period to watch in future updates.
Quick moving longwave trough swings over the central Plains into
toward the Ohio Valley Sunday into Monday, leading to another cold
frontal passage. While latest trends suggest frontal passage will
occur Sunday, timing differences between guidance become an issue by
this time period, so did not jump on either Sunday or Monday for
cooler temperatures with the update. Progged 850mb moisture ahead of
the front may lead to showers and storms as the feature moves south.
MVFR to VFR conditions are expected at all
three TAF sites as lingering showers continue across the
Panhandles through around 21z. A few isolated strong showers may
occur between 21z and 01z at all three sites. KGUY/KDHT will begin
to dry out after 01z with VFR conditions through the remainder of
the period. However, KAMA will see the chance for storms through
the overnight hours until the end of the TAF period. MVFR
conditions are possible with these storms, otherwise VFR
conditions are expected. Winds will be out of the south southwest
at 10 to 15 knots with gusts up to 20 knots possible through 18z
tomorrow. KGUY will begin to see the winds become westerly near
18z as a cold front approaches the Oklahoma Panhandle.
TX...Flood Watch through Wednesday morning for the following zones:
Moore...Ochiltree...Oldham...Palo Duro Canyon...Potter...
OK...Flood Watch through Wednesday morning for the following zones:
Area Forecast Discussion
National Weather Service Buffalo NY
1104 PM EDT Tue Oct 1 2019
Expect an unsettled weather pattern to continue into the remainder
of the work week as a slow moving frontal boundary sags south across
our region later tonight and Wednesday...then remains in our
vicinity through Thursday. This feature will act as the focus for
several rounds of showers and some embedded thunderstorms... while
also ushering in progressively cooler air. By Friday daytime highs
will only be in the lower to mid 50s...with the first frost or
freeze of the season then becoming possible across interior sections
.NEAR TERM /THROUGH WEDNESDAY/...
Regional radar shows initial round of thunderstorms that produced
some wind damage earlier this evening in Niagara county have exited
into eastern NY. A few other showers are streaming into southwest
NY, but otherwise there is a break in most showers until you reach
central lower Michigan. Though cannot rule out a few showers or
thunderstorms into the early overnight hours, as is occurring over
western NY, looks like most of the more organized showers and
thunderstorms will not arrive back over western NY until after 3-5
AM. Showers and thunderstorms upstream are on perifery of upper
level ridge and driven by stronger disturbance riding the ridge.
Activity is in swath of 1.8-2.0 inch pwats and on edge of higher
MUCAPES. 0-1km shear in this area is also 20-30 kts suggesting low-
level cold pools can effectively be balanced and activity could
persist through the night as it moves toward western NY.
Latest HRRR seems to be latched onto this idea very well and
followed it heavily for this update. Kept pops lower into the early
overnight hours, then ramped up pops to categorical late tonight. As
we saw earlier tonight, gusty winds could again be a hazard late
tonight through daybreak Wednesday. And with the abnormally high
PWATS and higher freezing levels toward 14kft, heavy rain is a
concern. Will have to watch if training storms develop as upper
level flow becomes parallel with sfc front settling across NY by
Wednesday morning. Kept gusty wind and heavy rain mention in grids
with expected evolution of convection late tonight into mid morning
Risk for stronger storms and should then fade by later Wednesday
morning as the front becomes increasingly anabatic in nature and we
become embedded more deeply within the cooler airmass to its
north...and accordingly see available instability diminish.
As mentioned previously...the bulk of the more widespread showers
and embedded thunder will occur from late tonight through the first
half of Wednesday...before slowly diminishing from north to south
Wednesday afternoon and evening as the frontal boundary makes
further southward headway across Pennsylvania. With the 12z model
guidance continuing the trend of previous runs of a somewhat faster/
further southward progression of the front during Wednesday...have
sped up the timing of the improving trend a little more from
continuity... with the rain completely coming to an end across the
North Country... and diminishing to some scattered showers across
the Niagara Frontier and much of the Finger Lakes during the
afternoon. This said...low clouds will still hang tough across all
areas south of Lake Ontario right through Wednesday given the
cool/moist northeasterly upslope flow regime to the north of the
front...with only the North Country seeing some partial sunshine
develop during the afternoon.
With respect to temperatures...the gradual southward progression of
the frontal zone will induce a notable north-south gradient in
temperatures both tonight and Wednesday. Lows tonight will range
from the mid 50s across the North Country to the mid 60s across
the Southern Tier...with the ongoing steady cool air advection
regime and widespread cloud cover on Wednesday then keeping highs
from rising more than a couple degrees above these values. In fact...
its actually more likely that most locations will just continue
to see slowly falling temperatures through the bulk of Wednesday...
with readings dropping into the 50s in most places (and perhaps
even to the upper 40s across interior portions of the North Country)
by early Wednesday evening.
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
By Wednesday evening the frontal zone will be into Pennsylvania,
with the best chance for showers across the Southern Tier which will
be closest to this boundary. Clouds will hold tough south of Lake
Ontario due to a northeasterly upslope flow. Meanwhile, high
pressure will ridge southward into the North Country where a partial
clearing is expected. Temperatures will be much cooler Wednesday
night, but clouds and a moderate northeasterly flow will limit
radiational cooling with low temperatures mainly in the 40s. The
exception is across somewhat sheltered interior portions of Lewis
and Jefferson counties where some frost is possible.
Thursday and Thursday night a sharp mid level trough will move from
the upper Great Lakes to southern Quebec. The forcing ahead of this
wave will allow a wave of low pressure to develop along the stalled
frontal zone to our south. This surface low will then move across
New York State late Thursday afternoon and evening. Model guidance
has been in poor agreement concerning the strength of this surface
low, which lowers forecast confidence for this time period. Showers
are likely move across the region during this period, with these
more numerous Thursday afternoon and evening. A few thunderstorms
are possible across the Western Southern Tier. These depend on the
track of the low and if it is able to break into the warm sector
ahead of the cold front. Either way, a cool northwesterly flow will
develop across the region Thursday night. Consensus 850mb
temperatures will drop to near zero Celsius by daybreak Friday and
this will support lots of lake effect clouds and some lake enhanced
rain showers Thursday night and into Friday morning. Even after the
showers end, expect Friday will be a mostly cloudy day. As a result,
the forecast holds in cloud cover longer during the day Friday, and
hedges cooler than consensus guidance.
The coldest air of the young autumn season will be upon us Friday
night. Though temperatures begin to warm some aloft, a broad surface
high will track to right over the region by Saturday morning. This
will create excellent radiational cooling conditions, with clear
skies and light winds allowing for temperatures to drop into the mid
to upper 30s on the lake plains and upper 20s to lower 30s across
the interior Southern Tier and east of Lake Ontario. Widespread
frost or freeze conditions are becoming more likely for Friday night
for a good portion of our area away from the Lakes.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
It will be a crisp start to this period with post sunrise
temperatures Saturday morning around freezing to the upper
30s. Surface high pressure will be nearby to our east and this
feature will allow for ample sunshine to support a nice rebound
in temperatures Saturday afternoon...into the upper 50s to
Sunday through Tuesday look to be wet as a large scale trough sets
up over our region. There are model differences, with the ECMWF
actually forming a cut off low within the base of this trough by
next Tuesday, while the GFS moves the upper level large scale
features along. The slower ECMWF will allow for rain chances into
Tuesday, whereas the faster GFS brings high pressure and drier air
into our region for the last day of this period. Will continue with
rain shower chances through this period as a surface baroclinic
boundary wavers across the region. Gulf of Mexico moisture will
enhance the low level moisture along this frontal boundary such that
moderate to heavy rainfall is possible along the slow moving front.
Temperatures Sunday and into early Monday will side towards above
normal...while later Monday and Tuesday behind this surface frontal
boundary temperatures will drop back close to normal.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
The frontal boundary to the north will slowly press southward across
our region through the balance of tonight and Wednesday morning.
This will bring widespread showers and scattered embedded
thunderstorms, mainly after midnight. As we saw Tue evening, some of
the storms could produce locally heavy rainfall and gusty winds. The
resultant increase in low level moisture (both from the precip and a
developing cool northeasterly upslope flow behind the front) will
result in flight conditions lowering to the LIFR to lower-end MVFR
ranges overnight and Wednesday morning.
Wednesday afternoon the front will make further southward progress
across Pennsylvania...and this will allow the showers to come to
an end across the North Country...and become more scattered across
the remainder of the area north of the Southern Tier. This said...
a continued cool northeasterly upslope flow will keep widespread
lower clouds and associated LIFR to MVFR flight conditions in place
across most areas south of Lake Ontario...with only portions of the
North Country possibly seeing some improvement to VFR.
Wednesday night and Thursday...Areas of IFR/MVFR with numerous to
widespread showers at times.
Friday...Mainly VFR with a chance of showers.
Sunday...Mainly VFR with a chance of showers.
Through Wednesday a slow moving cold front will slowly sag southward
across the Lower Great Lakes. This could bring a few more
thunderstorms with locally gusty winds and higher waves... but more
importantly will induce a wind shift to the northeast... with a
moderately brisk flow developing across Lake Ontario very late
tonight and Wednesday. This will bring advisory conditions to Lake
Ontario during the day Wednesday.
Looking a bit further out in time...even stronger northeasterlies
should then produce solid advisory-level conditions across the
western two thirds of Lake Ontario Wednesday night and Thursday.
Meanwhile on Lake Erie...a period of marginally advisory-worthy
conditions will be possible in tandem with a period of increased
northeasterly flow late Wednesday and Wednesday night.
A more summerlike day today yielded record highs at ROC (88F
breaks previous record of 86F set in 1877) and ART (83F breaks
previous record of 80F set in 2002). BUF fell short of record
high as that site saw a high of 81F (Record high is 83F set in
MARINE...Small Craft Advisory from 8 AM Wednesday to noon EDT Thursday
Small Craft Advisory from noon Wednesday to 6 PM EDT
Thursday for LOZ042.