Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/20/18
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
535 PM MDT Sun Aug 19 2018
.AVIATION...
00Z TAF CYCLE
Upper high center to move from AZ over NM durng the next 24 hrs. Sfc
high pressure to continue building strongly swd into the eastern NM
plains and along the east slopes of the central mt chain thru 20/12Z,
with lcl MVFR cigs obscuring terrain possible from KRTN to KLVS and
K0E0 aft 20/06Z. A gusty east wind into the RGV at KABQ and KSAF is
expected to develop, with gusts from 25kt to 35kt. A few showers and
tstms to sag swd from ne NM at 19/23Z into east central and se NM, an
isold strong to severe storm with hail and wnd gusts to 50kt
possible before 20/03Z. In addition, lcl MVFR vsbys due to HZ/FU will
be found from the RGV westward to the AZ border. HRRR smoke model
indicates vsbys will improve in the RGV once the east wind develops,
but may linger in the San Juan/Animas Valleys thru 20/12Z.
&&
.PREV DISCUSSION...330 PM MDT Sun Aug 19 2018...
.SYNOPSIS...
A moist back door front will dive through the eastern plains and into
the central valley with a gusty east wind below canyons tonight. The
strongest wind will be below Tijeras Canyon where gusts may reach 45
mph after midnight. The front will trigger scattered to isolated
showers and thunderstorms along and especially east of the central
mountain chain overnight. Although the front will improve low level
moisture some, very dry air aloft will limit shower and thunderstorm
development to the mountains on Monday. High temperatures will also
trend downward a few to several degrees across central and eastern
areas on Monday. A more traditional monsoon flow will develop
Tuesday through the end of the week as the subtropical high pressure
system builds east of New Mexico steering a persistent plume of
subtropical moisture over the state from the south and southwest.
This will result in daily rounds of scattered to at times numerous
showers and thunderstorms over western, northern and central areas.
High temperatures will vary from near normal to around 6 degrees
above normal.
&&
.DISCUSSION...
Thunderstorm outflows from convection on the eastern plains should
give the gusty east canyon wind a little extra push tonight. Models
are forecasting borderline advisory speeds at KABQ overnight, but
these should be a little stronger due to the thunderstorm outflows.
Very dry air aloft that moved over the state from the northwest in
the wake of yesterday`s upper level trough will remain in place
through Monday. This will limit thunderstorm development again. The
subtropical high will move over south central parts of the state
from the west on Monday. Meanwhile an upper level low pressure
system will move into the Pacific northwest, and this will begin to
draw some subtropical moisture northward over southern NM under the
ridge. Thus, the best coverage for showers and thunderstorms on
Monday will be over the southern high terrain, where scattered to
isolated activity is expected.
Depending on the model, the subtropical high is expected to center
somewhere around Texas or the lower Mississippi River Valley Tuesday
through the end of the week. There will be a marked increase in
thunderstorm coverage and rainfall intensity starting Tuesday
afternoon. A more active period for storms may be Thursday as an
upper level trough crossing the northern and central Rockies
interacts with this moisture.
44
&&
.FIRE WEATHER...
A backdoor cold front will move across the northeast plains this
afternoon and continue to the west and southwest tonight. The front
will interact with sufficient moisture and surface heating to
generate isolated showers and thunderstorms across the northeast
plains and adjacent highlands this afternoon and evening. Stronger
storms will be capable of producing large hail and damaging wind
gusts. The backdoor front will produce isolated to scattered showers
and thunderstorms across the eastern plains tonight. As the front
moves across the central mountains, east to southeast gap winds in
the Middle Rio Grande Valley will range between 25 to 40 mph with
gusts of 35 to 50 mph late this evening and overnight. Relative
humidity recovery will be good to excellent across most of the area
tonight, except to the west of the Continental Divide, where fair
recovery is expected. As the backdoor cold front stalls just to the
west of the Continental Divide Monday, increasing low level moisture
behind the front will result in minimum relative humidity from 25 to
40 percent east of the central mountains and between 15 and 25
percent from the central mountains to the Continental Divide.
Relative humidity will fall below 15 percent across the Northwest
Plateau and Northwest Highlands Monday afternoon. High pressure
aloft will drift eastward over NM Monday, and light winds aloft will
contribute to surface winds less than 15 mph across the entire
region. Ventilation rates Monday will be good across the Northwest
Plateau and poor to fair across the rest of the region.
As the upper level high shifts eastward into West TX Tuesday,
subtropical moisture will increase slightly across western and
northern NM. Scattered showers and thunderstorms will develop Tuesday
afternoon and evening across portions of western and northern NM.
Slow storm motion Tuesday afternoon and evening will create the
potential for flash flooding. Minimum relative humidity Tuesday will
be above 20 percent across the entire region, and winds will be 5 to
15 mph across western and central NM and 15 to 20 mph across eastern
NM. Ventilation rates will be good to excellent across much of the
region Tuesday, except for areas of fair ventilation across portions
of western and south central NM.
As the upper high progresses further east Wednesday through next
weekend, a south to southwest flow aloft over NM will continue to
transport subtropical moisture northward across NM. Daily rounds of
showers and thunderstorms can be expected through this period with
the greatest chances across western and northern NM.
28
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from midnight tonight to 6 AM MDT Monday for the
following zones... NMZ519.
&&
$$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
813 PM MDT Sun Aug 19 2018
.UPDATE...
Issued at 804 PM MDT Sun Aug 19 2018
Precip has ended across the entire area as upper
level low is over the central Plains. Main change
for the rest of tonight into Mon will be adding
smoke across the plains which will eventually
spread into the higher terrain as well. Visibilities
across ern WY have been in the 3-5 mile range which
have spread across the border into nrn CO. HRRR Smoke
model shows areas of smoke spreading across most of
the plains overnight and into the higher terrain
on Mon.
&&
.SHORT TERM...(This evening through Monday)
Issued at 227 PM MDT Sun Aug 19 2018
Water vapor imagery showing upper low over central portions of
Nebraska this afternoon with some energy still rotating around the
upper low over northeast colorado. This has resulted in scattered
showers and a few thunderstorms to break out over the plains. As
the low continues to push away from Colorado, showers will
diminish by early evening along with loss of daytime heating.
With clearing skies expected tonight and under cooler airmass,
overnight lows will drop into the 40s over a good portion of the
plains tonight.
For Monday, the high pressure ridge will build back into Colorado
with a drying and stable airmass. No storms expected with some
warming of temperatures in the afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 317 PM MDT Sun Aug 19 2018
Models show northwesterly flow aloft continuing Monday night. The
upper ridge axis slides back eastward into the CWA Tuesday
continuing through Wednesday night. The flow aloft stays west-
southwesterly through those periods. There is some synoptic scale
energy over the CWA Tuesday afternoon and evening. The low level
winds are expected to be east and southeasterly Monday night and
Tuesday into Tuesday evening. Maybe weak drainage later Tuesday
night. Southeasterlies dominate on Wednesday with drainage
Wednesday night. For moisture, precipitable water values gradually
increase on Tuesday and stay in the 0.75 to 1.30 inch range into
Wednesday evening. Moisture decreases overnight Wednesday. There
is quite a bit of mid and upper level moisture over the CWA from
Tuesday morning into mid day Wednesday. There is a tad of CAPE
over the southwestern CWA Monday evening. There is decent CAPE
progged late day Tuesday for the mountains, foothills and Palmer
ridge. There is little to none over the plains. On Wednesday and
Wednesday evening, CAPE increases a bit more and covers all of the
CWA except the eastern border. The QPF fields get pretty excited
Tuesday night with decent amounts of measurable rainfall over
much of the CWA. The current going pops are pretty high already.
Will keep or go with 30-60%s mid day Tuesday keep through Tuesday
night. Mainly just "scattered" pops for the mountains late day
Wednesday. For temperatures, Tuesday`s highs are 0-2 C cooler than
Monday`s. Wednesday`s highs come up about 2-5 C from Tuesday`s
highs. For the later days, Thursday through Sunday, there is a
weak upper trough to move across Colorado on Thursday and Thursday
evening. For Friday and Saturday, flat upper ridging is in place.
On Sunday, the upper ridge center migrates eastward into the
southeastern United State, with a fetch of south and
southwesterly air aloft for the CWA. Moisture is fair on Thursday
then again on Sunday. The best pops will be over the mountains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 804 PM MDT Sun Aug 19 2018
Winds have diminished and may switch to a light north to northwest
component in the next few hours. After midnight they will
become light southwest. Areas of smoke may affect the area
after midnight into Mon morning. There is some potential
for visbilities of 3 to 5 miles late tonight into Mon.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...RJK
AVIATION...RPK
Area Forecast Discussion
National Weather Service Columbia SC
1039 PM EDT Sun Aug 19 2018
.SYNOPSIS...
Surface high pressure in the Atlantic will extend westward along
the Gulf Coast through Monday. North of this ridge troughing
will be in the forecast area. The pattern supports scattered to
numerous showers and thunderstorms with near normal temperatures
through Tuesday. Drier air and a reduced chance of rain expected
mid week with lower humidity and near to slightly below normal
temperatures.
&&
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
Weak upper troughiness over the region with some weak upper
impulses moving through early tonight. Surface trough across the
western Carolinas. Latest radar indicates litttle activity over
our forecast area (FA), with some activity to our north along an
apparent weak surface boundary. Latest HRRR still indicates
some convection may move into, or develop over, the northern
Midlands later tonight presumably due to track of upper impulse
and interaction with the surface boundary. So, will leave in
chance POPs for that area.
&&
.SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
An upper level trough pushing into the Midwest will suppress high
pressure aloft off the Southeast U.S. coast during this time period.
Moist southwest flow will be over the region, and a weak shortwave
passing north of the area could amplify diurnal convection on Monday
evening. As the trough progresses eastward on Tuesday, convergence
ahead of a cold front will bring scattered to numerous showers and
thunderstorms. The front will also bring increased shear, and there
is a marginal risk for isolated severe storms across the Upstate
and northern Midlands. Temperatures will be near normal with highs
around 90 and lows in the low 70s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
In the wake of the cold front, Canadian surface high pressure
will impact the region through the end of the week. This airmass
will bring somewhat cooler and noticeably drier conditions to
the Southeast U.S.. Daytime temperatures will be in the mid to
upper 80s while overnight lows will be in the 60s. Precipitation
chances will be minimal Wednesday through Friday. Onshore flow
will return on Saturday and Sunday bringing diurnal convection.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VFR conditions through 08Z.
There is a possibility of stratus redevelopment early Monday
morning but confidence is limited with only the NAM showing the
stratus while other guidance not indicating cig restrictions.
The SREF also keeps IFR/MVFR stratus well west of the TAF sites.
May also see MVFR vsbys develop 09Z-13Z given abundant low
level moisture and near calm wind. Any early morning
restrictions should lift by late morning.
High moisture with precipitable water near 2 inches combined
with heating and convergence into the weak surface trough
supports scattered thunderstorms after 18Z.
EXTENDED AVIATION OUTLOOK...Areas of late night and early
morning stratus and fog are possible during the outlook period.
There will also be a chance of mainly afternoon and evening
thunderstorms.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
239 PM PDT Sun Aug 19 2018
.SYNOPSIS...Hot and dry conditions will continue through Monday,
followed by a cooler pattern during the remainder of the week.
Otherwise, smokey conditions will persist across much of the
region during the work week.
&&
.DISCUSSION...An upper-level trough will move toward Oregon and
California tonight with models now coming into better consensus
regarding its placement. Cooler temperatures are expected Tuesday
as the trough swings through the area. High temperatures across
the interior are forecast to be in the mid 80s to low 90s, with
seasonable temperatures along the coast. In addition, a slight
chance for an isolated thunderstorm exists over northeastern Del
Norte county Tuesday afternoon and evening, but the greatest
threat should be north and east of the region.
Current visible satellite imagery shows smoke and haze impacting
much of the region, which supports the inherited Air Quality
Advisory in effect for Hoopa, Orleans, Weitchpec, Lewiston, and
Trinity Center. Recent HRRR smoke guidance indicates a large area
of smoke will spread south from wildfires in British Columbia
during the next 24 hours, which could impact northwest California
by Monday night.
&&
.AVIATION...As promised stratus made a triumphant return along the
coast last night and has been hanging tough much of the morning. As
winds and heating have begun to increase early this afternoon
clearing has begun at ACV and CEC. Across the interior smoke from
area wildfires continue to blanket the region with reduced
visibilities, currently UKI is reporting LIFR conditions due to
smoke. Expect generally MVFR to IFR visibilities and opaque smoke
layers to persist through this taf cycle.
As was the case yesterday, by early this evening expect coastal
stratus to redevelop along the entire coast bringing IFR to LIFR
ceilings and visibilities to ACV and CEC. These conditions will
prevail through Monday morning. /WCI
&&
.MARINE...The brisk northerly winds and steep seas will continue to
impact the waters through Monday evening. The one exception is the
northern inner waters where winds and seas will continue to
gradually decline through the afternoon. The southern waters will
continue to experience very brisk northerly winds especially near
and downwind of Cape Mendocino through tomorrow where occasional
gale force gusts are possible. Model guidance continues to show
northerly winds decreasing in intensity Monday afternoon and evening
which will allow seas to also gradually subside. Light to moderate
southerly winds develop along the Mendocino coast by Tuesday morning
and across the rest of the waters by Wednesday morning as a low
pressure center moves offshore. Winds will become northerly again by
mid to late week. /WCI
&&
.FIRE WEATHER...Nocturnal offshore flow is expected to continue
through Monday night across interior Del Norte county. Gusts to
25 mph are possible along the ridge tops. Otherwise, hot and dry
conditions, with temperatures in the 90s, will continue through
Monday. In addition, a small chance for an isolated thunderstorm
exists across northeastern Del Norte county Tuesday afternoon,
though confidence is low.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until
5 PM PDT this afternoon for PZZ450.
Small Craft Advisory until 9 PM PDT Monday for PZZ470-475.
Small Craft Advisory until 9 AM PDT Monday for PZZ455.
&&
$$
Visit us at http://www.weather.gov/eureka
Follow us on Facebook and Twitter at:
http://www.facebook.com/NWSEureka
http://www.twitter.com/nwseureka
For forecast zone information
see the forecast zone map online:
http://www.weather.gov/eureka/zonemap.png
Area Forecast Discussion
National Weather Service Glasgow MT
850 PM MDT Sun Aug 19 2018
.DISCUSSION...
Evening Update (9pm MDT): Mostly cosmetic changes to the forecast
for the evening package. PoP chances were brought down a touch
tomorrow as some more uncertainty in exact placement and intensity
creeps into even the near term. Winds were also lowered for the
overnight as most sites are already light and variable, but the
afternoon winds were kept mostly the same. Dramatically dropped
MinT for tomorrow morning, especially in the far east, as cloud
cover will be minimal and 40s instead of 50s may be likely for
many locations east of Glasgow. The rest of the forecast was in
good shape.
Bigelbach
AFTERNOON UPDATE: Northeast Montana will remain on the cool side
of the cold front through Tuesday. There is an upper ridge in
place now, and a developing trough off the NW Coast. As the trough
moves inland, rain showers & thunderstorms will spread over
Central Montana. A shower or two may drift into our area on
Monday. But most of the storm energy moves into SE MT & Wyoming by
Monday evening. Overrunning moisture and a fluctuating frontal
boundary may generate local isolated overnight showers through
Tuesday.
Monday with its cooler air will see temperatures about 10F degrees
cooler than normal. Expect around 5F degrees cooler than normal
for Tuesday. Wednesday should see near normal temperatures.
Smoke: The Experimental HRRR Near Surface Smoke model suggests
clearing from the northeast today. Visibility sensors at the
airports show improving visibility. We will have smoke of varying
intensity until the wildfires are put out, probably from a large
wet storm moving over western Canada & the Pac-NW. There is such a
storm that is showing up on GFS & ECMWF for early next week.
Templer
Previous discussion for mid-week and beyond:
Expect a broad weak high pressure area at the surface to develop,
and east to southeast winds will allow temperatures to gradually
increase through mid- week, even with the upper low moving into
central Montana. Thursday the upper low will move across northeast
Montana, bringing a chance of thunderstorms to our southern
zones. Even so, surface moisture is expected to be limited, so
little precipitation is anticipated with this. Dry lightning may
be a concern, but it is still a little too early to tell for sure.
Beyond this, model solutions diverge somewhat, but suggest a weak
shortwave moving across the area at some point next weekend, with
a stronger system early next week. Even with a few models
suggesting this, dramatic changes often occur that far out, so
went with the model consensus.
Hickford
&&
.AVIATION...
Flight Category: VFR to possible MVFR
Smoke: There is still a mass of wildfire smoke over much of the
state, and over the northeast. Currently conditions are well in
VFR for the sites but other smaller airports have been reporting
visibility down to near MVFR levels. These conditions are expected
to remain generally that way through tomorrow at least, but the
nature of the smoke remains quite variable and thus needs close
monitoring.
Precipitation: A weak disturbance may possibly bring some isolated
VCSH activity to the region tomorrow, mostly to the west, which
could impact GGW. Otherwise, dry conditions are expected to
generally continue for the next several days.
Wind: Expect light and variable winds tonight for much of the
region, with a strengthening to 5-10 kts tomorrow afternoon out of
the northeast.
Bigelbach
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Grand Junction CO
528 PM MDT Sun Aug 19 2018
.SHORT TERM...(Tonight through Monday night)
Issued at 354 PM MDT Sun Aug 19 2018
The main weather concern for most people within our CWA through
Monday is the smoke which continues to move into our area from
wildfires near and far. HRRR model still forecasting an increase
of low level smoke into our CWA tonight, especially after
midnight and continuing on Monday. A shortwave disturbance in the
flow over our area late Monday and Monday night should decrease
the amount of low level smoke but will not likely get rid of all
of the smoke, especially the higher altitude smoke. That same
disturbance will likely produce scattered showers and thunderstorms
over northeast UT and northwest CO favoring the mountains.
.LONG TERM...(Tuesday through Sunday)
Issued at 354 PM MDT Sun Aug 19 2018
The models are showing the upper high center drifting slowly
eastward across NM Monday night and Tuesday, and then into TX by
early Wednesday. This will result in a southerly flow allowing
subtropical moisture to flow northward into our CWA Tuesday and
Wednesday for increasing showers and thunderstorms. Models
indicate precipitable water values rising to just over an inch in
SE UT and into SW CO, which may be a tad conservative. Anyway,
we`ll be monitoring the recent burn scars and other flash flood
prone areas very closely for any heavy rainfall which may occur on
them. And we will be relying on our storm spotters, emergency
managers, law enforcement, and others, in addition to the
automated rain gauges, to keep us informed with near real-time
ground truth information on measured rainfall and any rainfall
runoff impacts.
The GFS is still indicating a decrease in showers and
thunderstorms beginning on Thursday, though the EC is not showing
as much of a downturn, as the flow aloft becomes more westerly
across our area. Then both models show significantly more drying
on Friday under that westerly flow aloft, though there still may
be a few late-day high-based thunderstorms over the mountains.
Any drying later in the week might be short-lived as the GFS is
indicating subtropical moisture spreading back up into our area
from the south beginning on Saturday and continuing through the
weekend. EC is also showing a return of subtropical moisture, but
later in the weekend than the GFS and initially more to the east
of our CWA. Both models appear to be quite similar by Sunday with
implications of some heavy rain showers within our CWA at least in
SW CO and the SE corner of UT.
Max temperatures should be near normal throughout our CWA for
most of the long term forecast period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 528 PM MDT Sun Aug 19 2018
VFR conditions will prevail at all TAF sites over the next 24
hours as a strong ridge of high pressure builds to the west.
Wind gusts to 25 knots will be possible through 03Z before winds
diminish after sunset. Smoke from the numerous ongoing wildfires
in the western U.S. will continue to filter into eastern Utah and
western Colorado with localized areas of reduced visibility
expected.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...JRP
LONG TERM...JRP
AVIATION...MMS
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
931 PM CDT Sun Aug 19 2018
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
The last of the evening convection was noted over Webster and Clay
counties and may spread into northern Lowndes before dissipating
during the next hour or two. Much of the area will remain dry
tonight but latest HRRR and other hi-res models still indicate
potential storms back over our northwest zones prior to sunrise.
Have removed pops the remainder of the night across most of the
CWA but wl maintain pops over the Delta region toward morning.
Patchy fog will be possible in the southeast along with morning
stratus expected across much of the CWA. Temperatures were
adjusted in areas that received rain this evening but morning lows
were on track for mid 70s at most locations. /22/
Prior discussion below:
Tonight: An active period of weather will continue through
tomorrow as a closed mid/upper-level low is progged to propagate
from the Central Plains into the Midwest by tomorrow evening. This
will send an associated surface cold front towards the area with
continued showers and thunderstorms along and ahead of the front.
Through the rest of today, the greatest thunderstorm coverage
continues to remain along the Hwy 84 and I-59 corridors where the
greatest destabilization has occurred outside of this morning`s
widespread cloud coverage. Latest visible satellite imagery
indicates a cumulus field trying to develop in a ring around the
dense high clouds left over from the convective complex over the
northwest Delta. A few showers have already managed to develop
along the western Ashely County line in southeast Arkansas with
additional development further south expected. The main
uncertainty continues to be convective evolution through the rest
of this afternoon into this evening as hi-res CAM guidance
continues to struggle on both spatial and temporal scales. The
current forecast thinking is for an eventual composite outflow
boundary from the southern convection to gradually push north
towards the I-20 corridor and initiate additional convection.
Additional outflow boundaries and interactions would help foster
continued showers and storms further into the heart of the CWA,
however this will be conditional as to how much destabilization
ends up being realized where cloud cover is slower to dissipate.
While a few strong to isolated severe storms with locally damaging
winds remain possible, coverage will remain too low to mention in
the HWO/graphics. The ongoing area wide limited risk for flash
flooding will also be kept as is due to recent heavy rains. By
tonight, convection will begin to dissipate with loss of daytime
heating, however there`s decent agreement that a dissipating line
of showers and storms could enter the Delta late tonight into
early tomorrow morning.
Monday: The main focus will be the encroaching cold front and
associated convection both along and ahead of the front. Showers
and thunderstorms are expected to get an early start my mid to
late morning, especially along and southeast of the Natchez Trace
corridor as daytime heating commences in a moist environment. No
severe weather is expected from this early activity, however
locally heavy rainfall and isolated flash flooding will remain
possible. While timing differences remain, the main focus will be
for a broken line of convection to enter the Delta along the cold
front during the mid to late afternoon hours and propagate east
through the early evening. While mid-level lapse rates remain weak
(5.5-6 C/km), increasing tropospheric wind fields will yield
upwards of 35-40kts of 0-3km shear which will be juxtaposed with
2500-3500 J/kg of SBCAPE. Mid/upper-level dry air will also be
moving in resulting in upwards of 1200 J/kg of DCAPE in area
average forecast soundings. As such, have included a limited risk
for severe weather in the HWO/graphics with the main threat being
damaging wind gusts and hail up to quarter size. Given the
aforementioned parameters, an eventual upgrade to a slight risk
cannot be entirely ruled out if confidence in coverage and
convective evolution increases. /TW/
Monday night through Saturday: Anomalous mid level cold core over
the mid MS valley will drag a cold front into the area at the
beginning of the period. As it plows into a moist and unstable
airmass primed from daytime heating with PWs near 2 inches, a good
concentration of showers and thunderstorms will likely be ongoing
over the ArkLaMiss Delta region. Some risk of severe looks to
continue into the evening hours given the frontal forcing and 20-30
knots of deep layer shear, but these storms should wind down
somewhat by midnight with the loss of daytime heating.
The frontal boundary will slow down considerably after midnight and
limp into central sections by dawn Tuesday. Daytime heating and
frontal convergence will support more convection by Tuesday
afternoon over the south, but severe threat appears minimal as deep
layer shear relaxes.
While the drier air spreading into the area behind the front will
lead to less overall convection and cooler overnight lows, the
August sun will become quite efficient at warming the airmass each
afternoon; still being able to boost max temperatures into the lower
90s. This will be the case through Friday as high pressure over the
mid MS valley maintains low level northerly flow.
As high pressure shifts to the east Saturday, resulting low level
easterly/southeasterly flow will finally begin bringing low level
moisture back into the area. This will promote a return of diurnal
convection heading into the middle of the weekend./26/
&&
.AVIATION...
00Z TAF discussion:
Dissipating TSRA activity was resulting in IFR conds in the nw and
se at 2330Z. These conds wl improve before lower flight conditions
develop again by 08Z. Most of the current TSRA activity wl
dissipate by 02Z but additional TSRA development wl be psbl after
06Z in the north again. Away from TSRA VFR conds wl cont until
after 08Z when widespread MVFR/IFR cigs are expected. Conds wl
improve by mid Monday morning but scattered to numerous TSRA
activity is expected to develop early again. /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 74 89 73 90 / 8 44 43 26
Meridian 73 88 74 90 / 7 53 28 42
Vicksburg 75 91 72 91 / 10 42 42 20
Hattiesburg 73 87 74 91 / 7 59 26 56
Natchez 74 90 73 91 / 9 41 37 29
Greenville 72 89 71 88 / 34 40 57 11
Greenwood 74 88 71 88 / 19 46 56 14
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
TW/22/26
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1025 PM EDT Sun Aug 19 2018
.SYNOPSIS...
A weak cold front will drop into the northern forecast area
late tonight and Monday, then lift back north Monday night and
Tuesday. Another cold front will move through the area Thursday,
then stall off the coast into next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1010 PM Sunday...Increased POPs to likely over NW half of
area for overnight hours, and continued likely POPs along coast
toward morning. Increasing shortwave energy from NW and surface
front approaching from north expected to increase coverage of
showers and tstms overnight as supported by latest HRRR and
NAM12. Coverage has already increased past 1-2 hours near old
sea/sound breeze bounday between KEWN and KPGV. A few stronger
wind gusts will be possible with cell mergers and clusters but
main threat will be locally heavy rain and minor flooding. Rest
of forecast on track.
/Previous discussion/
As of 230 PM Sunday...Precip timing and coverage difficult with
mdls showing wide variety of solutions. Think as instab
increases with heating thru this aftn will see sct shra/tsra
develop with best coverage inland especially along sea breeze.
Better coverage will cont inland during the evening and then
late tonight models mostly agree best precip chc will be closer
to coast. Overall have mainly chc pops thru the evening then low
likely near coast late. Limited instab shld keep storms below
svr lvls however high precip wtr values will lead to locally
heavy rainfall. Lows mostly low/mid 70s.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 230 PM Sunday...Weak/ill defined cold front will be near
nrn tier thru the day with limited forcing aloft. Shld again see
enuf sun for highs well into the 80s leading to decent instab.
Expect another day with mostly sct shra/tsra with better
coverage near coast in morn shifting inland during the aftn.
Modest instab and weak shear will again limit svr threat with
locally heavy rain a good bet.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 310 AM Sun...A mean upper trough is forecast over the
Eastern US through the period while low level southerly flow
continues to circulate a very moist airmass across our region
with PW values AOA 2". The favorable combination of forcing
aloft and moisture/instability in the low levels will result in
unsettled conditions through the first part of the week with
precipitation chances at or above normal and temperatures at or
slightly below normal. Shower and thunderstorm chances increase
above climatological norms through mid week as conditions remain
favorable for scattered to numerous showers and thunderstorms.
Monday night through Tuesday...A weak front is forecast lift
back north Monday night and early Tuesday. Highs in the mid to
upper 80s through mid week, and overnight lows in the 70s.
Wednesday through Sunday...Another cold front will approach the
area mid to late week. There are still some timing differences,
with the GFS much more progressive and pushes the front through
quite a bit faster than the ECMWF. Expect the front to push
through the area Thursday, then likely remained stalled off the
coast into the weekend as strong high pressure builds in from
the north. Expect to see a drier airmass build into the area
with lesser precip chances. Highs in the low to mid 80s. Some
guidance has lows dropping into the low/mid 60s late week and
next weekend.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term /through Mon/...
As of 750 PM Sunday...Current VFR conditions expected to persist
into overnight, then some sub-VFR CIGs likely developing 08Z-
13Z with IFR threat mainly KPGV and KISO. VFR returning for
most of Monday. Scattered showers/tstms lingering along sea
breeze will remain in vicinity of KEWN and KOAJ next few hours
then expected to diminish. Additional activity expected to
develop overnight with short wave energy and surface front
approaching from north and enough support to include TEMPO for
MVFR SHRA all sites 08Z-12Z. Scattered convective coverage for
most of the day Monday.
Long Term /Monday night through Thursday/...
As of 310 AM Sun...Scattered to numerous showers and storms
will produce sub-VFR conditions at times through the period. In
addition conditions will be favorable for periods of low clouds
and fog early each morning. A cold front will push through the
area Wednesday night and Thursday.
&&
.MARINE...
Short Term /through Mon/...
As of 1020 PM Sunday...No significant changes with update.
/Previous discussion/
As of 230 PM Sunday...Winds gusts have been below 25 kts past
cpl hours and seas 5 ft outer buoys so will drop SCA rest of
today central and srn wtrs, however will likely remain just
below. Gradient expected to loosen overnight as weak front sags
toward nrn wtrs and stalls thru Mon. SW winds will become light
N of Cape Hat tonight into Mon and could see variable dir at
times. S of Hat SW winds will cont 15 to 20 kts this evening
then mainly 10 to 15 kts late tonight and Mon with still poss
some gusts to 20 kts. Seas will subside to 2 to 3 ft N. Over
srn tier seas will be mainly 3 to 5 ft tonight and 3 to 4 feet
Mon.
Long Term /Monday night through Thursday/...
As of 310 AM Sun...A weak front is forecast to lift back north
Monday night and early Tuesday. S/SW winds return for all
waters Tuesday 5-15 kt early increasing to 10-20 kt in the
afternoon. Seas 2-4 ft early building to 3-5 ft Tuesday night.
Gradient tightens Tue night and Wed, with SW winds increasing to
15-25 kt and seas building to 3-6 ft. Could see a brief period
of SCA conditions Tue night into Wed, with best chances across
the central waters. A cold front is likely to push through the
waters Thursday then stall off the coast into the weekend. Winds
will shift becoming NE/E 5-15 kt.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...RF
NEAR TERM...RF/JBM
SHORT TERM...RF
LONG TERM...CQD
AVIATION...JBM/CQD
MARINE...RF/JBM/CQD
Area Forecast Discussion
National Weather Service Omaha/Valley NE
626 PM CDT Sun Aug 19 2018
.SHORT TERM...(Tonight through Wednesday)
Issued at 400 PM CDT Sun Aug 19 2018
At 4 PM, fairly vigorous shortwave trough (by August standards)
was digging southeast through central Nebraska, with a 1007 mb
surface low over east central Kansas. An area of rain with a few
embedded thunderstorms extended from the Ozarks north into South
Dakota. Rain amounts over our region so far today have been in
the 0.25-1.75 inch range, with the highest totals reported in the
Lincoln area.
The primary concern/focus of the forecast is the potential for
very heavy rainfall this evening and overnight as the surface low
in Kansas shifts northward, deepens, and slows. This will place
southeast Nebraska and southwest Iowa in a region of strong
isentropic lift with PW values near 1.9 inches, and favor the
development of a heavy (possible convective) rain band between 7
PM tonight and 7 AM Monday. Recent runs of the NAM/HRRR/and RAP
generally support this scenario. Due to the potential for rain
rates near 2 inches per hour and training of heavier
precipitation, a Flash Flood Watch has been issued for the region.
Forecaster confidence in storm total rain amounts in the 2-6 inch
range is moderate. There is some potential for the heavier
rainfall to occur over the Omaha or Lincoln metros. Rain should
slowly dissipate through the day on Monday, with the chance of
heavy rainfall falling off quickly during the morning. High
temperatures will be mild for August on Monday, with afternoon
highs in the low to mid 70`s.
Drier weather is anticipated Tuesday and Wednesday, with afternoon
highs running in the upper 70`s each day. No hazardous weather is
anticipated.
.LONG TERM...(Wednesday night through Sunday)
Issued at 400 PM CDT Sun Aug 19 2018
After another dry day on Thursday, a chance of thunderstorms
returns to the forecast Friday, as a shortwave traverses the
northern Plains. Model trends over the last couple days have been
trending strong with this shortwave, increasing forecaster
confidence in the potential for rainfall. The forecast for next
weekend continues to fluctuate, with recent GFS/ECMWF trends
favoring dry weather Saturday and a slight chance of showers
Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 623 PM CDT Sun Aug 19 2018
IFR to occasional MVFR conditions are expected through much of the
TAF cycle as a strong system brings widespread rainfall to the
region through the overnight hours and into Monday morning. In
addition, gusty northerly low-level winds are expected to increase
overnight as the low pressure system passes through the region.
This should create areas of low-level wind shear from 05z-13z or
so.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch through Monday morning for NEZ015-033-034-
043>045-050>053-065>068-078-088>093.
IA...Flash Flood Watch through Monday morning for IAZ043-055-056-069-
079-080-090-091.
&&
$$
SHORT TERM...Albright
LONG TERM...Albright
AVIATION...Kern
Area Forecast Discussion
National Weather Service Raleigh NC
933 PM EDT Sun Aug 19 2018
.SYNOPSIS...
A cold front will move into central NC tonight, then stall overhead.
This boundary will return northward late Monday night into Tuesday.
A strong cold front will cross the area late Wednesday and Wednesday
night.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 930 PM Sunday...
Couple of surface boundaries set up across the forecast area this
evening. One across the NC/VA border where some persistent
convection has been occurring for several hours. Backbuilding
precipitation has led to an area of greater than five inches of rain
across northern Person County. This is the greatest area of concern
at this time. A second, currently inactive boundary a bit south of
the first and running more southwestward down US 1 has upper 70s
dewpoints southeast of it with some low 70s north of it. Convective
allowing models suggest that this may become a focus for convection
later this evening as the HRRR in particular shows this area
becoming active after midnight. Pushing back to a more synoptic
frame of reference, a wave off to the west will continue to push
southeastward into the area overnight and may provide some
additional support for ascent during the overnight hours. Do not
expect much in the way of severe activity, however the slow moving
nature of the convection this evening could lead to more flooding
issues. Overnight lows generally in the lower 70s.
&&
.SHORT TERM /MONDAY NIGHT/...
As of 340 PM Sunday...
The sfc boundary is projected to lie close to highway 64 by early
Monday. This sfc front will serve as a focus for scattered
convection Monday afternoon. Severe parameters a little more
impressive with shear values approaching 30kts across the north with
MLCAPE values 1600-2000 J/kg. This would suggest that the convection
may organize into broken bands, enhancing the threat for locally
damaging wind gusts. Convective allowing models suggest that
convective will be random, with not much organization.
The approach of a stronger s/w, crossing the mid MS Valley, will
induce a sly flow over central NC Monday night. This will push the
stalled boundary north back into Virginia by early Tuesday. The
retreating boundary may trigger additional showers and isolated
thunderstorms overnight Monday night.
Widespread low clouds Monday morning will inhibit insolation and
deter temperature recovery a bit. Once the sun breaks through,
convection will quickly fire, adding another hurdle to temperature
recovery. Thus, highs Monday will likely stall in the mid-upper 80s.
If the extensive low clouds hold on until mid day/early afternoon,
then highs across the northern counties may end up 3-4 degrees
cooler than forecast. Lows Monday night near 70-lower 70s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 132 pm Sunday...
Two main weather stories during the long term:
1. Severe thunderstorm risk late in the day Tuesday.
2. Cooling/Drying trend for Thursday through Saturday.
First, the severe weather threat: With the approach of an amplified
mid/upr trough, we`ll see deep warm/moist s/sw flow ahead of it and
warm sector destabilization on Tuesday. As a prefrontal sfc trough
approaches late in the day, in conjunction with increasing deep
layer shear with the approach of the mid/upr trough, the ingredients
for isolated to scattered severe tstms will come together. Deep
layer shear progs, along with forecast soundings and hodographs
suggest storm mode will be mostly multi-cell cluster with straight-
line winds being the main threat, however there`s enough low level
shear to support the potential for a couple isolated supercells.
Timing for such a line of tstms appears to be later in the day, or
mainly evening hours. Shower and tstm activity expected to wind
down overnight. Then on Wednesday, the sfc cold front and upper
trough axis are forecast to move through, so will need to keep a
chance for showers/tstms in the forecast for Wednesday afternoon,
but the best forcing for such activity (and severe storms) will have
exited, so any pcpn on Wednesday should be fairly light. Temps
Tuesday and Wednesday near-normal.
Second, the cooling/drying trend: In the wake of Wednesday`s cold
front and upper trough passage, look for cool/dry air advection
along with high pressure building to our north. That will set up
central NC to have a period of pleasant weather Thursday and Friday,
perhaps even lasting through most of Saturday, with temps several
degrees below normal (highs in the lower 80s and lows in the upper
50s to lower 60s). There are hints that a coastal trough may bring
moisture back into eastern NC over the weekend, but the bulk of that
moisture (and rain chances) right now appear to remain mostly to our
east and south.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 750 PM Sunday...
An upper level disturbance can be seen on water vapor this
evening rotating east. There is a leftover boundary from earlier
convection just north of KRDU and KRWI this evening and the NSSL
WRF is showing current convection across the north pushing south
and igniting along this boundary. Other high res models aren`t
as impressive, but also are not handling current trends well
either. Given the orientation and location of current mesoscale
boundaries have kept TAFs advertising this solution.
Monday morning, convection will quickly decrease in coverage as
the upper level low centers over the northeastern United
States. As this happens, another round of low level stratus will
be possible. NAM soundings have latched on to this signal with
the GFS not as robust (cigs confined to the triad). Given what
happened last night and very similar sounding profiles, think
the stratus will happen. Some sub IFR restrictions will also be
possible towards KGSO and KINT which future TAF packages might
need to include.
During the day Monday, the upper level low will exit east across
the region with another round of showers and thunderstorms
possible in the afternoon. Some gusty winds will be possible in
any of the heavier showers and thunderstorms as dry air exists
in the mid to upper levels.
Outlook (00z Tuesday through Friday): The atmosphere will
remain moist and unsettled across central NC through mid week,
leading to rounds of scattered convection, and lengthy periods
of early morning low clouds. A cold front is expected to cross
the region Wednesday evening with drier air filtering in behind.
This will lead to a period of VFR conditions Thursday and
Friday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...WSS
NEAR TERM...Ellis
SHORT TERM...WSS
LONG TERM...NP
AVIATION...Haines
Area Forecast Discussion
National Weather Service Springfield MO
621 PM CDT Sun Aug 19 2018
...Updated for 00Z Aviation Discussion...
.SHORT TERM...(This evening through Monday)
A large shield of showers and thunderstorms extended deep into
extreme southeast Kansas and the Missouri Ozarks this afternoon.
This was in response to an unseasonably strong upper level low
pressure system, that was circulating over the central Plains.
This feature has a surface reflection centered over east central
Kansas, which helped to bring in an airmass rich in moisture, and
slightly more unstable.
Determining if organized thunderstorms will develop late this
afternoon and early evening was the primary forecast challenge
today. Some of the CAMS models showed deep convection, while
others have not.
Shear will be strong for the time of year, however, instability
levels are in question. A Special RAOB was performed at 2pm to
assess how unstable the Ozarks airmass really was. We are
especially focused on the lower distribution of cape, and how much
of it exists.
The HRRR shows organized line segments to developing within an
environment containing 0-3km shear vector magnitudes of around 35
knots. If sufficient low level cape is present, we could
experience pockets of damaging winds, and even a couple of spin up
tornadoes.
Showers and thunderstorms will linger at random late tonight and
into tomorrow. South central Missouri could have a marginal to
slight risk for additional thunderstorms tomorrow. Look for highs
in the low 80s on Monday.
.LONG TERM...(Tuesday through Sunday)
Fall like weather is expected through the rest of the work week as
rain chances end Monday evening. With northwest flow keeping a
cool continental airmass over the region, temperatures will warm
up into the low to mid 80s on an afternoon basis through Thursday.
An upper level speed max is signaled by the models to approach by
Friday, bringing a chance for showers and thunderstorms.
As mid level heights rise toward next weekend, models do suggest a
warming trend, with temperatures back in the 90s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 621 PM CDT Sun Aug 19 2018
A line of strong to severe thunderstorms are moving across
southwest Missouri. The line has cleared KJLN, but KSGF and KBBG
will see strong to severe thunderstorms in the next few hours. IFR
visibilities/ceilings along with strong winds likely with this
line, and the potential for tornadoes will also continue. This
line will move east of KBBG and KSGF by 03Z, but still some
remaining showers/storms are not out of the question the
remainder of the night. Mainly VFR conditions then expected behind
the line, although some local MVFR ceilings will be possible in
any remaining showers. Another chance for convection will occur
late in the TAF period.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Cramer
LONG TERM...Cramer
AVIATION...Raberding
Area Forecast Discussion
National Weather Service Shreveport LA
933 PM CDT Sun Aug 19 2018
.UPDATE...
Convection quickly diminishing and moving out of our NE zones
attm. A remnant outflow boundary remains to the south and west of
the complex of storms currently across Central Arkansas attm but
not seeing any renewed convection along it and not seeing much in
the way of cumulus forming along the boundary in the GOES-16
Nighttime RGB data.
For the update, have trimmed pops back to slight chance variety
areawide as the HRRR still shows some very isolated convection
redeveloping during the overnight hours. Once again have thrown
out the latest 00z NAM output as it continues to suffer with
convective feedback issues.
Concerning temperatures, had to cool fcst mins across our northern
most zones where rainfall has resulted in temps below current
forecast mins. Likewise, warmed temps up a degree or two along the
I-20 Corridor.
The true cold front resides across S OK into NW AR attm and with
its passage south and east into our region during the afternoon
and evening hours on Monday, renewed convection is possible along
this boundary. Pop forecast for Monday looks good so no further
changes were necessary.
Update out shortly...13.
&&
.PREV DISCUSSION... /issued 631 PM CDT Sun Aug 19 2018/
AVIATION...
Another low confidence forecast with the 00z TAF package as once
again, short term progs are struggling with current convection and
future trends. The 18z NAM output suggests we will see a line of
convection push through the entire region overnight, effecting all
terminal sites and this does not appear likely. GFS is struggling
on current placement of convection and appears to be well overdone
as well. Have based the 00z TAF package on the latest run of the
HRRR which suggests that the TXK/ELD/MLU terminals have the most
likelihood of seeing evening convection before most if not all
convection dies off late tonight.
We will need to watch for renewed convection by late morning into
the afternoon hours along a southeastward moving cold front on
Monday and have thus added VCTS to all but the TXK/TYR terminals
for this.
South winds near 10kts overnight will veer quickly to the
southwest on Monday with sustained winds near 10-15kts with higher
gusts ahead of the southeastward moving cold front.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 79 94 73 95 / 20 50 40 10
MLU 78 92 73 93 / 20 50 40 10
DEQ 72 90 66 89 / 20 10 10 0
TXK 74 91 69 90 / 20 30 10 0
ELD 76 92 70 90 / 20 50 40 10
TYR 79 96 72 94 / 20 20 10 10
GGG 79 95 71 94 / 20 40 20 10
LFK 75 94 75 95 / 20 40 40 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
13/13