Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/21
Please see the 00Z aviation forecast discussion below.
AVIATION...
Convection continues across the Rio Grande plains this evening, with
most of the activity well south of DRT. We will monitor the need to
add a mention of TSRA at DRT, but at this time we will leave that out
of the forecast. Additional showers may develop late this evening
into tomorrow morning, but the afternoon hours look favored for more
widespread showers and thunderstorms.
PREV DISCUSSION... /ISSUED 159 PM CDT Mon May 10 2021/
SHORT TERM (Tonight through Tuesday Night)...
Severe storms with large to potentially giant hail possible west
this evening...
A stalled cold front draped across the region from west to east,
with ample southerly flow at low to mid levels bringing rich
moisture into the region above it, are setting the stage for severe
storms this afternoon and evening, primarily west of US-281. A
corridor of 4000+ J/kg MUCAPE as analyzed by the RAP exists along
the Rio Grande, with 2500+ J/kg across the rest of south-central
Texas. Although the 18Z DRT special sounding still showed a decent
capping inversion, the expectation is that this will still mostly
erode away through the rest of this afternoon with a little help
from a weak shortwave and a brief window for some surface heating.
Deep shear of 40-50+ knots, highest NW, will be in place this
evening. Rotating storms are a high likelihood, and in this
environment we are yet again under the gun for the potential of very
large or even giant hail this evening over our western counties.
Damaging winds are a secondary threat. The sfc front will sag very
slowly southward through tonight, and there is a very low risk for a
tornado south of it this evening as SRH increases due to the LLJ
formation, but in general concern is very low for tornadoes. Despite
the marginal risk in place over the east half of our area for severe
storms, current local thinking is that storm chances are quite low
for at least areas northeast of La Grange to Fredericksburg for this
first event.
Concern for localized flash flooding may be slightly increased this
evening for primarily the Winter Garden region. With freezing levels
maxing out around 12-13kft and then falling closer to 10 kft by
Tuesday night, warm rain processes will occur but rainfall rates
shouldn`t be off the charts or anything. Rivers have had plenty of
time to subside since the heavy rainfall late April into early May
so river flooding is not of much concern. However, impacts such as
ponding on roadways or overflowing culverts could be seen in a few
places where heavier rains do occur with a couple hours of residence
time. Somewhat more impactful flash flooding could be possible across
our western CWA this evening. The 12Z WRF-NMM, for example, puts out
a bullseye of 4+" of QPF over Uvalde and Zavala counties, and the
HRRR suggests the potential for similarly high QPF over the Winter
Garden region. That area is the most parched overall, especially
along our southern border, so they can take a bit of rain, but will
have to keep a close eye on things today.
Storms will likely cluster and weaken overnight tonight over the
southwest half of the CWA. However, redevelopment of showers and
storms is anticipated Tuesday morning with off and on activity
throughout the day and much of the night. Nailing down timing and
location of storms is difficult but in the AM, chances will be best
over the northwest half and will eventually spread across the rest
of the area through the day. A broad-brushed marginal risk of severe
weather, primarily for large hail, will be in place. A marginal risk
of excessive rainfall is also in place across the area, although
storms should be relatively progressive so we aren`t likely to see
many localized totals during the day above the 1-3" range, if at
all. That said, given the antecedent wetness over some spots and
ample atmospheric moisture available as PWATs of 1.5-2" are still
progged over all but the northern Hill Country, we will still need to
keep an eye out for some localized flooding problems should heavier
rainfall rates arise. With the cloud cover and rain in place and the
front stalled near our southern border, rather cool temperatures are
forecast, topping out only in the 70s north and low to mid 80s
south/along the Rio Grande Tuesday.
LONG TERM (Wednesday through Monday)...
Our active weather pattern for the start to middle of the week should
come to an end by Thursday, but not before we squeeze out another
round of scattered showers with a few rumbles of thunder on
Wednesday. A weak mid level shortwave will move through from west to
east on Wednesday, resulting in some scattered showers and storms,
especially within an east/northeasterly sfc flow regime. Any remnant
rain showers should come to an end shortly after sunset on Wednesday
evening, mainly over the southern 1/3rd of the CWA.
South-Central Texas will be left under light northeasterly sfc flow
on the southern periphery of a weak sfc high as it settles in to our
north and east on Thursday afternoon. This should set the stage for
several cool mornings, with many places in the mid to upper 50s,
along with areas to the west and south in the lower to middle 60s. By
late Friday, the sfc high will begin to retreat and slide eastward,
allowing sfc flow to turn back out of the south, with sfc moisture
returning as well as the Gulf of Mexico opens back up for business.
The weekend looks to bring the return of a slightly more active
pattern back into the picture once again. Models are somewhat divided
on what will transpire by the start of next week, but are more in
agreement on the setup for the weekend. Two separate shortwaves will
ripple through the flow out ahead of a deepening long wave upper
level trough over the southwestern CONUS. This will allow isolated to
scattered showers and thunderstorms to develop both Saturday and
Sunday afternoons. At this time, the threat for severe weather looks
quite low, however, will continue to monitor the possibility of
strong to severe storms by Sunday afternoon and Monday afternoon, as
this type of pattern has led to severe weather in our region over the
last several weeks.
PREV DISCUSSION... /ISSUED 1248 PM CDT Mon May 10 2021/
AVIATION...
CIGs are hovering just below MVFR thresholds at SAT this afternoon
but should lift to VFR for a time. AUS is seeing a brief clearing but
it isn`t expected to last. Scattered thunderstorm development late
this afternoon through the evening has the potential to impact
DRT/SAT/SSF but confidence is low in direct impacts for San Antonio,
thus carrying VCTS there for now. Deteriorating flight conditions
return tonight with IFR by 03z at AUS and MVFR at DRT/SAT/SSF by
03-05Z. SAT/SSF could see IFR as early as 09/12Z but confidence too
low to include at this time. Somewhat better shower and thunderstorm
coverage is expected late tonight near DRT and then by the afternoon
hours Tuesday at the I-35 sites, details to be refined.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 62 73 61 69 59 / 40 90 70 60 20
Austin Bergstrom Intl Airport 63 75 61 69 58 / 40 80 70 60 20
New Braunfels Muni Airport 65 77 62 72 59 / 40 80 70 60 20
Burnet Muni Airport 59 71 57 66 57 / 50 90 50 50 20
Del Rio Intl Airport 69 81 66 75 63 / 40 60 50 60 30
Georgetown Muni Airport 61 72 59 67 57 / 50 90 60 50 20
Hondo Muni Airport 67 80 64 74 59 / 50 80 60 60 20
San Marcos Muni Airport 64 76 61 70 58 / 40 80 70 60 20
La Grange - Fayette Regional 69 81 64 72 61 / 40 70 80 70 20
San Antonio Intl Airport 66 78 63 71 61 / 40 80 70 60 20
Stinson Muni Airport 68 81 65 73 62 / 40 70 70 60 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...04
Long-Term...05
Decision Support...Platt
Area Forecast Discussion
National Weather Service Grand Junction CO
508 PM MDT Mon May 10 2021
.SHORT TERM...(Tonight through Tuesday night)
Issued at 219 PM MDT Mon May 10 2021
The closed low responsible for our unsettled weather this
afternoon remains over central Idaho at this hour. Flow around
this low, along with an upper level jet streak, and cooler
temperatures aloft have all combined to create a showery, and now
stormy afternoon. The HRRR and NAMNest are the big winners this
afternoon highlighting where convection has setup and tapped into
instability aloft. CAPE values of around 500 J/kg north of I-70
have also aided in said convection. For now, just seeing rainfall
amounts of .01 to .03 inches but expect under and near any storm
cores that number will be a bit higher. Also wouldn`t be surprised
if some of the stronger cells don`t bring some stronger winds to
the surface. Meanwhile down south, plenty of breaks can be seen in
the cloud cover which has allowed some deeper mixing to occur.
Thanks to the jet streak aloft, a few wind gusts of 50 mph have
been noted near Durango and Pagosa Springs this afternoon. Winds
have subsided some but expect the breezy conditions to persist
through sunset.
Overnight, the NAMNEST is hinting at an uptick in precip for the
San Juans as do other models, just not as much, so slightly upped
pops for the region. Still looking for some light snow overnight
in the 1 to 3 inch range for the higher terrain along the Divide
and onto the Grand Mesa.
Tomorrow, the midlevel circulation will have reached the Co/Wy
border and continue moving eastward. Like today, the best
instability and strongest CAPE (~300 J/kg) will be north of the
I-70 corridor, closest to the disturbance where the best lift will
be. Convection doesn`t look as widespread and looks to quickly
shutdown heading into the evening hours. Down south, another
breezy afternoon for the southern valleys.
High temps will remain below climatological norms today and again
tomorrow but a quick rebound will kick in Wednesday onwards.
.LONG TERM...(Tuesday night through Sunday)
Issued at 353 AM MDT Mon May 10 2021
A weak ridge begins to build in over the Desert Southwest on
Wednesday. Afternoon highs will increase a few degrees each day,
and, by the end of the week, are expected to be close to 10 degrees
above normal for mid-May. Conditions will remain generally dry
through the period. The next Pacific trough moves onshore Friday,
and is forecast to deepen along the California coast through the
weekend. Ensemble and deterministic models seem to be in pretty good
agreement about the general progression of this system, even
indicating the formation of a cut off low over northern California
Saturday morning. As this trough continues to deepen, the pressure
gradient over eastern Utah and western Colorado is expected to
tighten up, leading to enhanced afternoon winds for Saturday and
Sunday. The winds, combined with warm and dry conditions, may lead
to potential critical fire weather conditions for the weekend.
The low is currently forecast to move through the Four Corners
region Sunday night into Monday, but confidence is low with this
occurring at the end of the forecast period. The forecast is
likely to change in the coming days as models move into better
agreement.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 504 PM MDT Mon May 10 2021
Scattered showers and thunderstorms will persist at KVEL, KHDN,
KEGE, KGUC and KASE over the course of the evening. These showers
with produce gusty and erratic winds, but little in the way of
rainfall. VFR conditons are expected, although MVFR may be
possible with these showers. Shower activity will wind down and
become focused along the divide overnight and into tomorrow.
Another round of showers is expected in the central and northern
mountains tomorrow afternoon.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...TGR
LONG TERM...BGB/MDA
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Wilmington NC
1021 PM EDT Mon May 10 2021
.SYNOPSIS...
Scattered showers and thunderstorms will accompany a cold front
tonight. The front will stall offshore Tuesday with unseasonably
cool temperatures expected for the next few days. A soaking rain
may develop Wednesday as a wave of low pressure passes by to our
south. High pressure late in the week will lead to pleasant
weather conditions.
&&
.UPDATE...
Based on radar and latest HRRR and NAMnest convective potential
I`ve limited overnight shower and t-storm chances to areas along
and north of the NC/SC state line, focused mainly across
Robeson and Bladen counties where convection currently near
Charlotte and Albemarle move over the next few hours. Across
much of northeastern South Carolina away from the state line it
appears too much dry air exists to allow convection to form when
the front arrives. All other changes to the forecast were
minor.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Active weather period over the next 36 hours with strong to severe
thunderstorms expected and a good shot of cooler air heading toward
the region.
The forecast area currently is positioned in the warm moist sector
in front of an incoming cold front. Temperatures across the region
range from 85 at Wilmington to 73 at Hartsville with dew points in
the upper 50s to low 60s. This air mass in combination with
instability aloft with decent speed shear values will support the
possibility of severe thunderstorm development. Large hail,
damaging winds, and an isolated tornado are all possible. Based on
the latest satellite imagery and high resolution model guidance,
storms should develop by mid to late afternoon and continue through
the late evening through early overnight hours. Anywhere from 0.25
to 0.50 inches possible with higher amounts in the strongest
developing thunderstorms.
The cold front should pass by Tuesday morning and start a cooling
trend with afternoon highs Tuesday between 10 and 20 degrees cooler
than today in the upper 60s to mid 70s. Some chances for light
precipitation will continue along and behind the front through the
day Tuesday, although chances for severe weather is not anticipated
Tuesday.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Cold and wet day for Wed with northerly winds and continued CAA
as high pressure builds down from the Upper Midwest and cold
front lingers to the south. Increasing isentropic lift as a wave
of low pressure moves along lingering front to the south will
produce some decent rain across the Carolinas, mainly through SC
Wed aftn. The latest guidance shows max temps in the early
morning just below 60 and then remaining near steady or possibly
dropping through the day with temps in the mid to upper 50s for
much of Wednesday daytime hours. This could lead to record low
maximums for the day. The lowest max temp for ILM on Wed the
12th is 65, LBT is 65, MYR is 65 and FLO is 67.
Wave of low pressure will track off to the E-NE late Wed as high
pressure builds down from the north. Heavier rain should taper
off, with soundings showing some drier air moving in, but looks
like clouds and light rain or drizzle will hang on into Thurs
across the area. NAM soundings keep a saturated column into
Thurs with a steep inversion holding on to shallow colder air
into Thurs. For now, will keep chc of rain across much of the
area into Thurs as another wave of low pressure moves by to the
south and shortwave digs down from the north. Overall, cloudy
and cool and wet weather through the period with overnight lows
dropping below 50 Wed night inland and rebounding into the 60s
on Thurs.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Mid to upper trough running down from the Great Lakes will track
east and any shortwave energy will lift north. High pressure
extending down from the north will migrate eastward and offshore
through the weekend. Overall, expect clearing on Fri and dry
weather with NE winds veering around to onshore and eventually
southerly into early next week. May see some clouds increase Sun
into Mon as warmer, more moist air moves northward. Temps well
below normal on Thurs but plenty of sunshine over the weekend
will help temps rebound as air mass modifies slowly with a
return to normal by early next week.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
A cold front extending across central North Carolina should drop
south and across our area between 04-07z Tuesday. Scattered
showers moving across MYR early this evening are ahead of the
front, while we`ll be watching a broken line of convection and
possible t-storms just ahead the front itself that may impact
LBT and ILM mainly between 02-05z. Behind the front, low clouds
will spread in from the north and northeast and blanket the area
through a good portion of Tuesday. IFR conditions appear likely
to develop early Tuesday morning in the 07-12z timeframe and may
not lift above 1000 feet (MVFR) until afternoon at some
airports.
Extended Outlook...The cold front will stall offshore Tuesday. A
developing wave of low pressure will spread rain and low clouds
across the area late Tuesday night into Wednesday with MVFR to
IFR ceilings expected. Conditions should improve Thursday.
&&
.MARINE...
Through Tuesday night...Seas 4 to 6 feet with winds 15 to 20
kts gusting to 25 kts should continue through the early evening
with small craft advisory concerns ending by the late evening.
High risk for rip currents continue as strong southerly waves
around 7 seconds will impact south facing beaches. Seas become 2
to 3 feet through the night into Tuesday with windspeeds
generally at or below 15 kts. Main concern for sailing vessels
is the sharp wind shift that will occur as cold front approaches
and winds shift from the southwest to the north/northeast.
Wednesday through Friday...Persistent NE winds will continue
with cold front stalled just south and high pressure building
in from the north will produce a sustained period of SCA
conditions possible Wed to Fri with unseasonably cold air
running over the waters Wed into Thurs. Wave of low pressure
along the front will also help to enhance the winds and produce
unsettled weather through mid week. Shortwave will finally lift
off the the northeast on Fri as sfc high to the north migrates
east and offshore into the weekend. NE winds will veer around
slowly into the weekend.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
UPDATE...TRA
NEAR TERM...MCK
SHORT TERM...
LONG TERM...
AVIATION...TRA
MARINE...MCK/RGZ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
615 PM CDT Mon May 10 2021
.SHORT TERM...
258 PM CDT
Through Tuesday night...
Similar to much of May so far, the primary forecast items of
interest are low temperatures and potential for frost, which both
of these next two nights present for at least parts of the area.
Scattered showers developed early this afternoon in a broad
frontal convergence zone located along and about 60 miles south of
I-80. These showers have focused on the southern end of the
frontal zone, where there has been a few pulses of intra-cloud
lightning but otherwise fairly subdued. It looks like there is
continuing suppression further north behind the morning short
wave, which scooted along a little quicker than earlier thought.
That has limited any convective showers in the I-80 corridor area.
Steep low-level lapse rates and 0-3 km CAPE of 100 J/kg are
analyzed near I-80 and just south by the SPC RAP mesoanalysis,
where there is clearing and clumped cumulus. If some of that can
develop a little more as the suppression eases, there may still be
a few gustier showers in that area that shift southeast, but
confidence is not that high given observational trends. Further
north, a few showers are possible away from the lake shadow
(where there are cooler temperatures from the lake) due to cold
mid-level temps (500 mb of -24C) and surface heating.
For this evening, some showers may have a propensity to fester in
the far south with the slow movement of the surface boundary and
the continued passage of an elongated, sheared short wave in the
mid-levels. These should work their way south of the area and/or
dissipate by midnight. The north edge of low to mid cloud will be
slower to depart based on observational trends in the region and
guidance moisture progs. A north-to-south clearing is expected but
the rate in which that clearing occurs is uncertain. Northern
locations naturally have a higher confidence, and this is where
minimum temperatures in the mid 30s to pockets of lower 30s in
outlying areas are forecast. For this reason, a Frost Advisory has
been hoisted for these northern locations. For the I-80 corridor,
including far northwest Indiana, these locations are more
marginal for areas to widespread frost. Also far northwest Indiana
looks to have a light wind flow off the warmer lake. So no
Advisory at this time and the evening shift will further assess.
Tuesday should be a day without any precipitation, and it`s been
a little while since that (for instance, Rockford has had seven
straight days with at least a trace of precip). Canadian high
pressure of 1032 mb will gradually sprawls its way southward from
the Upper Midwest during the day, resulting in an early wind
uptick off the lake. With 850 mb temperatures being below 0C for
one more day, highs look to only peak in the 50s to 60 far west,
with again upper 40s near the lake. For Tuesday evening,
conditions are ideal for maximized radiational cooling and
temperatures below those forecast tonight. Future shifts will
assess the likely need for a headline, and it is possible some of
the area will require a freeze headline.
MTF
&&
.LONG TERM...
258 PM CDT
Wednesday through Monday...
It appears that Wednesday night into early Thursday will be the
last frosty night/early morning outside of Chicago in this
unusually cool stretch. North to northeast winds will be in place
again for Wednesday pushing lake cooled air across much of the
immediate Chicago metro and into northwest Indiana. This will keep
highs in the lower to mid 50s for these areas while the remainder
of the area sees low to mid 60s for highs. Dew points away from
the lake in the upper 20s to lower 30s at peak heating, followed
by light winds and clear skies under the surface high at night
should set the stage for good radiational cooling. Have areas of
frost mention in the interior Chicago suburbs and points inland,
and could envision needing another frost advisory for some of our
counties, with forecast lows in cool spots down to the mid 30s,
with isolated low 30s possible far north where it`s been driest
and given the favorable radiational setup.
The surface high will be shifting east Thursday suggesting more
of a southerly component to the wind, albeit with light speeds,
but potentially reducing the inland extent of lake cooling with
more of a southeast direction off the lake. However, speeds will
likely be light enough to allow a traditional lake breeze to
develop anyways. Guidance is also in good agreement on an upper
trough axis pivoting across the region but precipitation prospects
are quite low with this given a dry airmass being in place.
Another trough axis is forecast to move through later Friday,
though the dry surface high influence and dry antecedent air mass
appears favored to hold back precip chances until during the
weekend. Despite increasing mid clouds, nice air mass modification
will bring upper 60s to around 70 inland on Friday, while
lakeshore areas are limited to the upper 50s-lower 60s by afternoon
lake breeze push.
An unsettled upper pattern continues Saturday with better (but
still officially low-mid chance) shower chances on Saturday and
especially Sunday as more earnest warm advection arrives.
Instability progs are pretty meager, as well as mid-level lapse
rates, so kept slight chance thunder mention limited to Sunday PM.
Warming air mass aloft with increased cloud cover could keep max
temps in the upper 60s-lower 70s range through the weekend, while
still maintaining lakeside cooling from onshore wind component
into at least IL shore. Expect highs in the 70s inland by Sunday.
The upper ridge looks to crest the area Monday bringing even
warmer air (mid 70s away from IL shore) with it but shower/thunder
chances continue.
MDB/Castro
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Highlights:
* Northeast surface winds through the period, generally 10-15 kt
during daytime hours.
* Dry with VFR conditions through the period.
Diffuse surface cold front and weak low pressure reflection has
settled south of the terminals this afternoon, with showers and a
few thunderstorms to dissipate early this evening while remaining
well south. A mid-level trough rotating southeast through the
western Great Lakes region will maintain some VFR SCT-BKN cloud
cover into the overnight hours, with bases generally in the
6000-8000 foot range. Once this mid-level disturbance moves off
to the east of the area Tuesday morning, surface high pressure
will build southeast from the upper Mississippi Valley into
northeast IL and WI through Tuesday evening. This will maintain
northeast surface winds of generally 10-15 kts during the day,
before becoming somewhat light and variable Tuesday night in the
vicinity of the surface high pressure center.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Frost Advisory...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ011-
ILZ012-ILZ013-ILZ103...1 AM Tuesday to 8 AM Tuesday.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
856 PM EDT Mon May 10 2021
.SYNOPSIS...
A reinforcing cold front will cross the region Tuesday. High
pressure will build toward the region Wednesday, with the high
building overhead during latter portion of the week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
It is currently clear to partly cloudy, but clouds will be on
the increase overnight as a weak disturbance embedded in zonal
flow passes through. The HRRR even hints that a few light
showers may try to form across southwestern portions of the
forecast area. If any showers were to form, they`d be light and
brief in nature, so nudged POPs down below slight chance. Cloud
cover will keep temperatures warmer than they potentially could
be, with overnight lows ranging from the upper 30s in the
mountains, to around 50 in downtown DC and Baltimore.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
A mid-upper level trough currently centered over Lake Superior
will slowly drift southward toward our area during the day
tomorrow. This will drive a surface cold front southeastward
toward us. As the upper low drops southward, mid-levels start
to cool, and the surface cold front starts to cross the region,
showers are expected to develop in response to daytime heating
tomorrow afternoon. With equilibrium levels around -10 C, no
lightning is expected, but the showers could produce a brief
heavy downpour with gusty winds. While daylight heating loss
will cause showers to dwindle after dark, some may linger
especially over southern Maryland as the trough and front will
continue to act as forcing. Temperatures will be quite chilly
tomorrow night, with lows dropping into the 30s (to the west of
the Blue Ridge) and lower to middle 40s (to the east of the Blue
Ridge). A Freeze Watch remains in effect for most of the
Allegheny Front where temperatures are likely to be coldest.
Zonal flow aloft will be maintained on Wednesday as the upper
low to our north starts to move off to the east. At the surface,
high pressure will build toward the area from the Great Lakes.
The combination of building high pressure and zonal flow aloft
will lead to mostly sunny skies. Temperatures will hold below
normal (highs in the 60s) as northwesterly winds in advance of
the approaching high continue to transport seasonably cool air
into the area. As high pressure builds closer still Wednesday
night, wind may go weak enough for some spots to decouple. As a
result, frost/freeze headlines may potentially be needed again
to the west of the Blue Ridge.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Cyclonic flow begins to exit the northeastern U.S. on Thursday
with a split jet structure noted further upstream. A sprawling
ridge of surface high pressure extends from the Missouri Valley
into much of the eastern U.S. While a passing shortwave trough
will weaken this dome of high pressure, it should remain a
fixture in the forecast into the upcoming weekend. Models are in
agreement that height falls should move through the Mid-
Atlantic on Friday. Compared to this past weekend`s upper low,
this should be much less impressive in terms of shower
production. The vertical column is not nearly as cold,
instability is nearly non-existent, and wind fields aloft are
quite weak. However, will maintain a chance of some showers for
Friday. This system eventually induces cyclogenesis well off the
southeastern U.S. coast which is of no consequence to the Mid-
Atlantic region.
For the weekend, the northern stream is forecast to dominate
the pattern with prevailing northwesterly flow expected. This
will maintain the extended period of below average temperatures.
Depending on the level of amplification of the upstream flow,
some shower chances may intermittently impact the region over
the weekend. Confidence does remain low in the threat for
showers. Winds eventually become westerly by Sunday which may
bring temperatures closer to mid-May climatology. This would
favor mid 70s with 60s across the higher terrain. Will continue
to monitor the progression of an approaching warm front which
may aid in further warmth into next week. The composite of
global ensembles support a warming trend which also is indicated
in the Day 6-10 Climate Prediction Center outlook.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
VFR conditions and northwesterly winds are expected to
predominate at the terminals through Wednesday. Winds may gust
to around 15 to 20 knots at times. While no restrictions are
likely, a brief shower Tuesday afternoon as a cold front passes
could cause a brief reduction in vsby.
Thursday and Friday should bring VFR conditions to the
terminals. With surface high pressure in place, winds are to be
on the lighter side with variable directions at times. A few
showers are possible by Friday, but confidence is below average.
&&
.MARINE...
Winds will remain northwesterly through Wednesday, with gusts to
low-end SCA levels at times. The only opportunity for winds to
get stronger than low-end SCA will be tomorrow afternoon in any
convective showers that form. Coverage of these showers isn`t
expected to be high, but an SMW or two can`t be ruled out
tomorrow afternoon if these showers are able to bring higher
winds down from aloft.
Sprawling high pressure across the area will keep winds below
small craft levels for Thursday and Friday, and likely into the
weekend as well.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Freeze Watch from late Tuesday night through Wednesday morning
for MDZ001.
VA...Freeze Watch from late Tuesday night through Wednesday morning
for VAZ503.
WV...Freeze Watch from late Tuesday night through Wednesday morning
for WVZ501-505.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ531-532-539-
540.
Small Craft Advisory from 4 PM Tuesday to 6 AM EDT Wednesday
for ANZ530>534-536>541-543.
Small Craft Advisory from midnight Tuesday night to 6 AM EDT
Wednesday for ANZ542.
Small Craft Advisory until 10 AM EDT Tuesday for ANZ533-534-
537-541-543.
Small Craft Advisory from midnight tonight to 6 AM EDT Tuesday
for ANZ530.
Small Craft Advisory from 4 PM Tuesday to midnight EDT Tuesday
night for ANZ535.
&&
$$
SYNOPSIS...KJP/RCM
NEAR TERM...KJP/RCM
SHORT TERM...RCM/KJP/RCM
LONG TERM...BRO
AVIATION...BRO/KJP/RCM
MARINE...BRO/KJP
Area Forecast Discussion
National Weather Service Midland/Odessa TX
646 PM CDT Mon May 10 2021
.DISCUSSION...
See 00Z aviation discussion below.
&&
.AVIATION...
MVFR CIGs will return to MAF/HOB/INK/FST in the next few hours and
should drop to IFR after 06Z at HOB and MAF. Have kept CIGs IFR at
HOB/MAF until around 18Z when they scatter out of all terminals
but they may lift to MVFR for several hours prior to this. SHRA
and TS will develop around 12Z and while it is expected to remain
just east of the terminals, it could impact MAF and FST.
Confidence is too low to include in those TAFs at this time.
Hennig
&&
.PREV DISCUSSION... /issued 245 PM CDT Mon May 10 2021/
DISCUSSION...
Vis satellite imagery and surface observations show morning stratus
east of the Pecos is slow to erode this afternoon, aided by a steady
NE PBL flow. A cold front extended from near KCNM-KPEQ-KOZA, w/the
dryline banked up against the higher terrain, putting the triple
point invof KCNM.
In the bigger picture, WV imagery shows an upper trough crossing the
Gulf of CA at 18Z, and is due into West Texas and Southeast New
Mexico late tonight/Tuesday. Ahead of this, mesoanalysis shows a
tongue of 4000 J/kg nosing into Terrell County in the warm sector,
where 70+ dewpoints are creeping up the Rio Grande valley. Visible
imagery shows a cu field already going up down there, w/the HRRR
suggesting initiation around 20Z. Mesoanalysis shows mid-lvl lapse
rates in excess of 7 C/km in the warm sector, so a large hail threat
will be in play. Later tonight, convection is forecast to develop
north and west on a strengthening LLJ, as easterly sfc flow surges
moisture west. Lapse rates are forecast to moderate somewhat, but
still pose a marginally severe hail threat. Ensembles depict PWATs
of 2-3 devs above normal for the eastern zones, so a potential heavy
rain threat will exist as well. Tuesday, the dryline, already
banked up against the higher terrain, will mix very little east, and
then surge west Tuesday night, w/50F dewpoints as far in as
KATS/KCNM. A backdoor cold front will move SW through the Permian
Basin Tuesday afternoon, and to the Presidio Valley late Tuesday
night. This will collide w/the aforementioned Gulf of CA trough,
expanding the convective threat west. Best deep-lyr shear and
instability will be in the better moisture eastern zones,
maintaining a severe threat there.
Post-frontal temps Wednesday will remain below 70F across the
lowlands, w/cool NE flow keeping stratus socked up against the
higher terrain. Chances of convection will taper off to the east be
Wednesday evening. Weak ridging develops into the area Thursday, for
a gradual warmup to around normal by Sunday/Monday. Convection will
be possible Thu-Sat as perturbations move through the ridge, mainly
west, but this activity looks isolated for the most part.
FIRE WEATHER...
A Fire Danger Statement is out today for elevated fire conditions
across the Sacramento, Delaware, and Guadalupe Mountains as well as
Culberson county. RFTI values of 4 to 5 and RH as low as 7% will be
present. Fair to good overnight recovery is expected out there,
although relative humidity will drop down to critical levels again
on Tuesday. Another Fire Danger Statement may be needed. Storms are
expected to develop S of the Pecos tonight before moving northeast
through the region Tuesday morning. Gusty and erratic winds may be
possible with any of these storms, along with frequent lightning.
These storms look to produce some locally heavy rainfall, which may
tamper fire weather concerns for the foreseeable future. A cold
front moving through the area will cool temperatures through
Thursday to well below normal.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 54 69 51 61 / 30 30 30 40
Carlsbad 56 83 51 65 / 10 0 40 20
Dryden 66 86 61 70 / 20 20 40 50
Fort Stockton 61 85 54 65 / 10 10 40 40
Guadalupe Pass 57 78 49 62 / 10 0 20 20
Hobbs 53 73 48 61 / 10 10 30 30
Marfa 53 85 50 70 / 10 0 20 20
Midland Intl Airport 56 76 51 62 / 30 20 40 40
Odessa 56 76 51 62 / 20 10 40 40
Wink 59 83 53 66 / 10 10 40 30
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
99/99/10
Area Forecast Discussion
National Weather Service Shreveport LA
1011 PM CDT Mon May 10 2021
.UPDATE.../Tonight/
Convective evolution continues to be tricky to forecast, and hi-
res rapid update models haven`t been much help this evening. The
latest HRRR does seem to be initializing better this run, and the
12Z Euro is not too far off on placement of QPF thus far. If these
models have any handle on what will happen during the overnight,
convection should stay mostly confined to our nern half, generally
from around Tyler to Shreveport to Jena and points newd. have
increased PoPs across these areas for the overnight pd. Otherwise,
have made some minor tweaks to temps based on current obs, which
were running a few degrees cooler than previously fcst for the
central portions of the region. Otherwise, fcst is reasonably on
track this evening. /12/
&&
.PREV DISCUSSION... /issued 706 PM CDT Mon May 10 2021/
AVIATION...
There is much uncertainty with regard to convective
coverage/location this TAF pd. Have tailored TAFs to reflect
ongoing radar trends, but the picture becomes less clear for the
overnight through Tuesday. Safe to say that we will see multiple
rounds of tstms through the pd, which could impact any site in the
area. Otherwise, expect mostly IFR conditions to persist through
the pd. /12/
&&
PREV DISCUSSION... /issued 331 PM CDT Mon May 10 2021/
SHORT TERM.../Tonight through Tuesday Night/
Sct svr elevated convection continues to build SE into extreme NW
LA attm, riding along an area of higher MUCapes of 1000-2000 J/Kg
coinciding with the lingering H850 trough over the Red River
Valley of Srn OK/N TX into the Nrn sections of SW AR, where steep
lapse rates persist ahead of weak perturbations in the nearly
zonal flow. The 12Z CAMs, which somewhat initialized on this
convection this AM, suggest that it will weaken late this
afternoon/early evening, although additional convection
redevelopment is expected later this evening and overnight across
NE TX/SE OK/SW AR/possibly extreme Nrn LA, with the approach of
another perturbation in the flow that will interact with
increasing convergence along the H925 trough as it begins to lift
back N across E TX/NW LA into SW AR. Thus, have stair-stepped
pops back from chance to likely across E TX/SW AR by late evening,
before likely expanding pops farther E across the remainder of SW
AR overnight. Fortunately, these areas will be able to take the
rain tonight, with the weak cold front now over the Srn sections
of NCntrl LA into Deep E TX now expected to be much of a player
tonight as it should seep just S of the area this evening.
While there may be a brief lull in the extent of convection
Tuesday morning, weak sfc low development along the lingering sfc
frontal bndry just to our S may result in the bndry nudging back N
a tad into Deep E TX and Cntrl LA from the late morning and a
portion of the afternoon. This will occur as the upper trough
now swinging through the Great Basin into the Rockies ejects into
the Plains and dampens Tuesday, although this trough will advect
Pacific moisture NE ahead of the Baja upper trough and become
absorbed into the Nrn stream trough into the Srn Plains/Lower MS
Valley Tuesday. This will set the stage for convection becoming
more numerous by late morning and especially for the afternoon
areawide. While the setup is not typical for the transitional
heavy rainfall events, am concerned though of the proximity of the
sfc bndry to our S over areas that remain saturated in wake of
widespread heavy rainfall (3-7+ inches) and flooding that
occurred Sunday afternoon/evening over Deep E TX/WCntrl LA. Have
deferred a Flash Flood Watch for this area for the graveyard
shift later tonight, with the greatest threat for moderate to
potentially heavy rainfall over this area likely being late
Tuesday morning through Wednesday afternoon. Confidence is high
though such that pops have been increased to high end categorical
areawide Tuesday afternoon, before mid and upper level drier air
begins to entrain SE into NE TX/SE OK/SW AR Tuesday night. Thus,
rain rates will begin to taper off from NW to SE Tuesday night as
the aforementioned trough axis moves through the Srn Plains into
the Lower MS Valley. Did continue to undercut the NBM max temps
over much of the area Tuesday, as little warming will occur over
the cool sector with the increasing convection.
15
LONG TERM.../Wednesday through Monday Night/
By Wednesday, showers and thunderstorms will be ongoing along a
stalled 850mb front. With moderate to heavy rainfall expected
previous to this, some flooding issues could remain during this
time. However, by Wednesday afternoon, another trough will move
through the midwest. This will push the 850mb front through the
region, and rain chances will diminish from north to south.
Northwest flow will bring in drier weather for Thursday along with
slightly below normal temps. Look for this dry weather to continue
on Friday and Saturday as upper ridging builds into the region, but
a slight warm-up in temperatures will start during this period and
continue through early next week. The ridge starts to break down
late into the weekend and the flow will become more zonal. Rain
chances will return for Sunday and the first part of next week as
disturbances move across the region along the flow. /20/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 55 65 57 67 / 70 90 90 50
MLU 58 67 59 68 / 60 90 90 60
DEQ 53 59 52 67 / 70 90 60 20
TXK 54 59 53 67 / 70 90 80 30
ELD 53 62 53 68 / 70 90 80 40
TYR 57 64 56 68 / 70 90 80 40
GGG 54 64 56 66 / 70 90 90 40
LFK 67 78 62 68 / 50 90 90 60
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
12/15/20