Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/20/18
Area Forecast Discussion
National Weather Service Albany NY
1032 PM EDT Sat May 19 2018
.SYNOPSIS...
The steady rain will taper to scattered showers and
patchy drizzle early this evening. A cold front will bring a
renewed threat of scattered showers and isolated thunderstorms
tomorrow morning into the afternoon, as a drier air mass will follow
Sunday night into Monday with temperatures slightly above normal to
open the work week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1032 PM EDT...Main change with this update was to lower
pops for much of the area for the next few hours. Radar and
observations indicating rain/drizzle has ended for most of the
area. The only exception is across eastern Dutchess and
Litchfield counties, where scattered showers are moving through.
The HRRR backed off on the idea of elevated convective cells
over this area. The warm front is sill positioned to the south
and west of the forecast area and will take several more hours
to pass through.
Will mention mainly chance pops overnight, except likely along
the western spine of the Adirondacks and southern Greens as the
cold front approaches late. As we break into the warm sector,
it will become humid and dewpts will rise into the 50s to lower
60s. Some patchy fog will be around the area, and temps will
rise and steady into the 50s and lower 60s overnight. A cold
front will be approaching from the west by daybreak on Sunday,
and the chance for showers and thunderstorms will be increasing
across the northwest zones.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Tomorrow...The cold front quickly moves across the region in the
late morning into the early afternoon. Small amounts of
instability will be in place with limited sfc heating and
destabilization. A slight chance of thunderstorms was included
north and west of the Capital Region prior to noon, and then
from roughly noon into the early afternoon south and east. The
limited instability should limit the severe threat. There could
be some gusty winds to 30-40 mph, as a band of showers and
thunderstorms pivots south and east of the entire area after 5
pm. Decent low to mid level cold advection occurs in the wake of
the front. Downsloping in the west to northwest flow should
allow temps to spike into the mid and upper 70s in portions of
the Hudson River Valley including the Capital District south and
east with 60s to lower 70s over the rest of the region.
West/northwest winds will be brisk at 10 to 20 mph.
Sunday night...Clearing skies and seasonably cool conditions
are expected, as sfc high pressure builds in from the Great
Lakes Region over NY and New England. Lows will fall into the
40s with a few 50F readings in the Capital Region, mid-Hudson
valley and NW CT. A few upper 30s are possible in the southern
Dacks in the cold advection regime.
Monday-Monday night...A great start to the week is expected with
high pressure building in over the Northeast. Mostly sunny skies
and pleasant humidity levels with max temps slightly above
normal by 5 degrees or so with upper 60s to upper 70s for
highs. Some high clouds will increase from the south and west
late as in the relatively flat mid and upper level flow a low
pressure system will be moving moving from the cntrl MS River
Valley into the Midwest Monday night. Some weak warm advection
ahead of a warm front may kick off some shortly before just
after midnight over most of the forecast area. Lows will be in
in the 50s with some upper 40s over the northern zones.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
The long term forecast period will begin with a piece of northern
stream energy traversing the region bringing a chance for rain
Tuesday through Wednesday morning. Thursday and Friday will be
characterized by rising heights and dry weather.
Tuesday and Wednesday...A weak area of low pressure and the
associated cold front will progress through the region Tuesday
afternoon into Wednesday morning bringing some rain showers to the
region. Depending on the timing of the frontal passage there could
be a rumble of thunder Tuesday evening but forecast confidence is
low at this time due to differences of timing and placement of the
boundary suggested by the GFS/ECMWF. High pressure will begin to
build into the region Wednesday afternoon so conditions should dry
out and there may even be a few peeks of sun in the evening. High
temperatures will be in the upper 60s to mid 70s with lows in the
upper 40s to mid 50s.
Thursday and Friday...High pressure will build in from the west and
keep conditions dry/sunny. Late thursday into Friday there will be a
a quick moving piece of energy to our north which could bring some
additional clouds to the region. High temperatures will be in the
70s and perhaps into the low 80s for the Mid-Hudson Valley. Lows
will be in the upper 40s to mid 50s.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Poor flying conditions expected to prevail through the first
12-15 hours of the TAF period, as our region remains north of a
warm front. Widespread rain earlier today has resulted in a
deck of low stratus clouds and occasional light fog with patchy
light showers or drizzle. IFR conditions should generally
prevail at all TAF sites tonight into Sunday morning.
Gradual improvement is expected Sunday, as the warm front lifts
northward early in the morning, then a cold front pushes
eastward during the late morning to early afternoon hours.
Showers will accompany the cold front, but should act to
aid in mixing out some of the low-level moisture. So conditions
should improve from IFR to MVFR by around mid to late morning.
Then, further improvement will occur Sunday afternoon in wake of
the cold front passage, with drier air filtering into the
region and VFR conditions developing.
Low level wind shear is expected between around 00Z-12Z Sunday,
as a southwesterly jet moves overhead with relatively light
southerly surface winds. The LLWS should end after 12Z Sunday as
the jet shifts east of the region.
Surface winds will be southerly around 5-12 kt tonight, shifting
the southwest Sunday morning, then northwest behind the cold
front Sunday afternoon. Gusts around 20 kt are expected Sunday
afternoon, especially at KALB/KPSF.
Outlook...
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: Low Operational Impact. Slight Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Low Operational Impact. Slight Chance of SHRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
The steady rain will taper to scattered showers and
patchy drizzle early this evening. A cold front will bring a
renewed threat of scattered showers and isolated thunderstorms
tomorrow morning into the afternoon, as a drier air mass will follow
Sunday night into Monday.
Soggy conditions into tomorrow will limit any fire weather
potential the next 5 days. RH values will be around 100 percent
tonight and lower to 45 to 60 percent tomorrow afternoon.
The winds will veer to the south tonight at 10 to 20 mph. Gusty
west to northwest winds on tomorrow in the wake of the cold
front will occur at 10-20 mph with gusts around 30mph at times.
The winds will diminish Sunday night with high pressure building
in.
&&
.HYDROLOGY...
A widespread soaking rainfall will continue into tonight. No
widespread hydrological impacts are expected the next 5 days
ending Wednesday.
Total rainfall amounts are expected to be between 0.75 inches
and 1.50 inch range for the rest of today into tomorrow. Some
rises are expected on rivers, but no flooding is anticipated.
A drier air mass builds late Sunday afternoon through Monday
with the next of chance of rain arriving on Tuesday.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...JPV/Wasula
SHORT TERM...Wasula
LONG TERM...Cebulko
AVIATION...JPV
FIRE WEATHER...BGM/Wasula
HYDROLOGY...BGM/Wasula
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
826 PM CDT Sat May 19 2018
.DISCUSSION...Updated for latest marine discussion below.
&&
.MARINE...Wind observations around the Laguna Madre have already
fallen below 20 knots this evening, so have elected to expire the
Small Craft Advisory for Winds there and the 0-20nm Gulf waters a
bit early. Not thinking that gradient will be strong enough to
support a SCA on the Gulf waters overnight, even with the
nocturnal maximum, though likely to remain solidly in SCEC range.
Latest short-term guidance consistent with this idea, so have
updated winds and seas accordingly. Also reduced PoP`s to below
mentionable levels in the coastal waters overnight. Text products
updated and disseminated.
&&
.PREV DISCUSSION... /issued 626 PM CDT Sat May 19 2018/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...Surface troughing sagging southward from the Central
Plains toward northern Texas will maintain a moderately tight
pressure gradient over the next 24 hours. Breezy to gusty winds
observed currently at the RGV terminals will subside after sunset
but still remain 10-15KT overnight. MOS guidance and BUFKIT RAP
forecast soundings consistent in returning MVFR ceilings overnight
through late morning on Sunday. VFR should return thereafter, as
CIG`s lift/scatter out with breeziness again developing (though a
bit less than today).
PREV DISCUSSION... /issued 329 PM CDT Sat May 19 2018/
SHORT TERM (Tonight through Sunday Night): The ridge axis aloft ha
finally shifted east as the longwave trough digs across the western
US. This, along with a passing wave around the bottom of the trough,
is inducing low pressure deepening across the northern Panhandle
into SW Kansas. This deepening low has brought our winds upwards
today, generally reaching around 20 knots with some higher gusts.
This has also drawn moisture northward from the Gulf, making for a
slightly less hot, but much more humid day today. This is noted by
heat index values still right around 100 right now. The sfc low
remains steady in Kansas, keeping local gradient tight through the
night. Winds will stay around 15kts overnight, while moisture near
the surface will keep skies partly to mostly cloudy. Most of
tomorrow will be similar to today, with partly to mostly cloudy
skies and breezy southeast winds. Heat index readings will again
reach around 100 during the afternoon, especially right along the
river. The next wave rounds the base of the midlevel trough Sunday
night, and models are still noting convection trying to form on the
mountains in Mexico and sweeping to the northeast. While the chances
for full-fledged thunderstorms crossing the river are not great,
there still may be some leftover showers trying to move northeast,
along with some possible midlevel light rain spreading over the
western counties. Have made some adjustments to the rainfall
forecast, focusing things after midnight Sunday night when showers
might finally arrive.
LONG TERM (Monday through Saturday): Strong 500 mb troffing will
be digging down the West Coast starting Mon while broad 500 mb
troffing will be in place over much of the Gulf of Mex. In between
these two features weak ridging will prevail at the start of the
upcoming work week. Some decent deep layer moisture will be
located over eastern Mex and southern TX at the start of the work
week. This may result in some diurnally driven conv on Mon. Also
the conv potential may be enhanced a bit as a weak 500 mb short
wave moves over the region Mon. As the west coast troffing closes
off and shifts up to the NE, the moisture levels will gradually
diminish heading into the rest of the upcoming week which will
allow the pops to decrease. As the West Coast closed low shifts
northeast the ridging over South TX will build gradually west with
a generally hot and dry atms in place over the RGV into next
weekend.
The GFS and ECMWF models are in pretty good agreement in the
handling of the overall synoptic pattern over the RGV over the
upcoming week. Will stick with a general blend of the two models
for pops through Day 7 and will go a little on the warmer side of
guidance for high temps as both models seem to be underperforming
in the handling of the high temps.
MARINE (Now through Sunday night): Advisories remain in effect
through this evening for the Laguna Madre and Gulf water south of
20nm as winds continue to breeze northward around 20 knots. The
usual swapping of gusty winds will happen overnight, as the Laguna
winds relax to around 15 knots, but the Gulf waters beyond 20nm see
an increase of winds to around 20 knots. The advisory for the
nearshore gulf will likely be extended, and the farther offshore
waters will be added for the nighttime hours. Winds will again swap
in the morning, with Laguna winds jumping back up to 20 knots.
Monday through Thursday Night: The PGF over the lower TX coastline
will gradually weaken some next week allowing the winds and seas
to remain fairly low. Low to moderate E-SE surface winds will
prevail through next Thurs. No SCA conditions expected at this
time.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
53-Schroeder/59
Area Forecast Discussion
National Weather Service Des Moines IA
651 PM CDT Sat May 19 2018
.SHORT TERM.../Tonight through Sunday/
Issued at 336 PM CDT Sat May 19 2018
The primary concern into tomorrow will be precip trends with the
most significant convection, if any, this evening. Currently water
vapor imagery notes the upper low over the High Plains with a noted
PV anomaly and dry slot pushing through the MO Valley. This suggests
the steep mid level lapse rates are further north and east than
depicted by recent RAP objective analysis. Our window to realize
this isn`t great however with the 20z surface analysis placing the
cold front from between Creston and Lamoni to just south of
Waterloo, and any convergence of substance over southern IA near
Osceola and Chariton. The flow is fairly weak however so it won`t be
too strong. MLCAPEs in this area appear to be uncapped around 1000
j/kg so there is still some potential for re-development in the
wedge of clearing ahead of the front and behind the ongoing central
IA convective cluster. The effective shear is weak and RAP hail
parameters are not impressive, but the drying aloft per the
aforementioned water vapor imagery suggests a brief hail potential
may be greater than objectively analyzed. Plenty of low level
moisture and limited shear as created an unfavorable wind
environment outside of isolated downbursts as cores collapse. The
weak low level wind and shear will diminish much of the tornado
potential as well, however 0-3km CAPEs are quite high so isolated
thermodynamically dominate/stretched funnel clouds/landspouts will
be possible near boundaries, synoptic or mesoscale. Isolated
locally heavy rains are possible too with anomalously high
precipitable waters and slow cell movement. Isolated 1-3 inch rains
have already been report with a few storms.
Any appreciable instability and thermodynamic forcing should be
limited to this evening, however continued kinematic support ahead
of the upper low will linger into Sunday, especially the morning,
keeping chances for scattered showers and low end thunderstorms in
the forecast. There should be plenty of low clouds as well with
relatively light north to northeast winds doing little to scour
things out.
.LONG TERM.../Sunday night through Saturday/
Issued at 336 PM CDT Sat May 19 2018
Sunday night...A passing shortwave Sunday evening will keep shower
and thunderstorm chances going over the state but the instability
and shear will be tied to the boundary which will be well south
of the state so not looking at any kind of severe threat. It will
be a cool and wet period with non severe storms in the forecast.
Monday through Tuesday...An upper ridge will build over the
region but with a trough digging in the west, shortwaves will be
riding the backside of the ridge just to the west so it will be
mainly dry Monday with small chance PoPs creeping into mainly the
west Tuesday/Tuesday night.
Wednesday through Thursday, the upper ridge begins to shift east
as an upper trough passes into the Northern Plains. Weak waves of
vorticity move through ridge and across the state, increasing
PoPs across western/northern Iowa through this period but the
better instability still remains west until later Thursday/Friday
when the upper trough pushes into the Upper Midwest. We will see
more widespread showers/thunderstorms Thursday night into early
Saturday with the passage of the upper trough and surface
boundary, which should pass to the east of the state by mid-day
Saturday. Precip chances will then shift east later Saturday into
Sunday with cooler temps moving in for the latter part of the
weekend.
&&
.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 651 PM CDT Sat May 19 2018
Main concern through period will be showers exiting north this
evening; additional push of showers/thunderstorms south/east at
KALO/KDSM/KOTM from 03 to ~07z then lingering showers aft 12z
through 18z. Cigs will continue to lower behind the boundary/low
pressure currently exiting Iowa between 06-12z from north to south
with MVFR; at times IFR at most sites through much of period on
Sunday. Will update with latest trends at 06z. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Small
LONG TERM...FAB
AVIATION...REV
Area Forecast Discussion...UPDATED
National Weather Service Quad Cities IA IL
838 PM CDT Sat May 19 2018
.UPDATE...
Issued at 823 PM CDT Sat May 19 2018
The threat for severe storms tonight has diminished so the local
area has been taken out of the Marginal and Slight risk areas for
severe storms. Watching the trends over the past several hours,
the front has not had much luck developing convection and as the
area has such low deep layer shear, all storms that we`ve watched
this afternoon and evening have been pulse storms with slow
movement as they just didn`t have the shear to get organized.
Going forward tonight, the HRRR is still trying to convect on the
front, and radar is showing some of that happening, however it is
pretty isolated in nature at this time. So confidence in
widespread showers and storms tonight is pretty low. Sheer is
increasing though so if a couple of storms do develop, there might
be enough shear to sustain an updraft and get a few stronger
storms. But, while can`t say no chance for severe storms, the
likelihood is pretty low for tonight.
&&
.SYNOPSIS...
Issued at 220 PM CDT Sat May 19 2018
Rather complex weather scenario ongoing today. Weak surface flow
due to weak synoptic forcing made identifying frontal boundaries
difficult. Thunderstorms from overnight across central MO kept
clouds across the area early this morning. These clouds quickly
cleared out and lead to sufficient warming across the area.
Numerous MCVs were identified on the satellite this afternoon.
One, across central IA, led to the redevelopment of thunderstorms.
This will be one area to watch through the early short term
period. Another area will be NE KS where better flow and
instability will lead to the development of thunderstorms. These
storms could track towards the area later tonight.
&&
.SHORT TERM...(Now through Sunday)
ISSUED AT 220 PM CDT Sat May 19 2018
Water vapor verified the existence of an H5 wave moving north
through the flow into NE KS and NW MO. This coupled with a MCV
south of DSM lead to showers and storms this afternoon. These
storms will likely move north and expand across a surface
boundary. These storms will likely expand into the far western
zones. Gusty winds and small hail may be possible with these
storms. The threat for severe weather appears low with these
storms.
Latest HRRR runs have come in line with the 12z NAMnest,
suggesting upscale growth into a MCS tonight. While the flow is
weak overall, HIRES guidance suggests that H85 flow may increase
with MCS leading to a favorable environment for organized storms.
If this occurs, then there would be a tornado threat along with
the wind threat from the MCS tonight. Again, with weak forcing,
convection may not occur this way. We will need to watch for
convection forming anywhere in the warm sector.
Tomorrow, weak flow continues across the area. With boundaries
south of the area, thunderstorm development looks likely. Moderate
rain will likely occur across the area. A marginal risk for severe
weather is forecast across the far southeastern CWA.
.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 220 PM CDT Sat May 19 2018
Monday: Scattered showers are possible as the 500 mb shortwave
that is expected to bring thunderstorms over the region on Sunday
moves to the east. At 12Z Monday, the GFS/ECMWF are in agreement
in moving an energetic longwave trof on shore into southern
California and closing it off over Nevada. An upper level ridge
will build over the midwest in response to this energy moving
onshore. Surface high pressure will also begin to build into the
region from southern Canada, bringing with it pleasant weather.
High temperatures on Monday will be in the 70s, with overnight
lows in the 50s across the north, to around 60 in the south.
Tuesday: Surface high pressure will continue to build into the area
beneath the east side of the upper level ridge axis. This will make
for a dry and warm day with high temperatures expected to be around
80 in the north, with mid 80s over the south. Overnight lows will be
in the 60s.
Wednesday through next Saturday: Longer range models prog the upper
flow aloft to shift to the southwest as and upper ridge shifts east.
Confidence is low in timing a series of weak shortwaves progged to
move through this flow, bringing with them a chance of showers and
thunderstorms each day. Humidity levels will be on the rise as a
southerly flow at the surface advects warm and moist air into the
upper Mississippi Valley from the Gulf of Mexico. The combination of
temperatures in the 80s and dewpoints in the 60s will make for muggy
conditions. ..Kuhl..
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
ISSUED AT 655 PM CDT Sat May 19 2018
A frontal boundary is in play for the next 24 hours with rain,
thunder potential through tonight, followed by MVFR OR IFR
ceilings through at least the morning hours on Sunday. There is
considerable uncertainty with the showers and thunderstorms
tonight, so while there remains a good chance to see some
shower/thunder activity near all terminals, the timing is unclear
so used most probable timing. Throughout tonight, the front will
be dropping southward and remain south of the area through the
day. Winds will shift to the east/northeast and ceilings will
drop. IFR/MVFR ceilings are expected then and while models
indicate they could persist through Sunday evening, think that
might be too pessimistic and so did start to break the clouds up
by mid afternoon from south to north.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Brooks
SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Kuhl
AVIATION...Brooks
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
836 PM CDT Sat May 19 2018
.UPDATE... /ADJUSTED POPS HIGHER OUT WEST/
Repeated runs of the HRRR are falling in alignment with some of the
earlier HREF runs suggesting a small complex holding together through
the late evening before weakening. PoPs were raised to likely over a
small area of the southern Edwards Plateau, and nudged up slightly
for areas just west of San Antonio. Overnight PoPs were adjusted up
farther east to follow the trend of the weakening storm complex.
The HRRR trends indicate chances may need to increase over the
Coastal Prairies toward daybreak perhaps as streamer showers, but
without much support from other models and lack of an expected
surface or mid-level focus, will disregard that feature for now.
&&
.PREV DISCUSSION... /ISSUED 634 PM CDT Sat May 19 2018/
AVIATION...
Convection over northern Mexico and western Val Verde County will be
affecting KDRT for the next few hours. Could see TS gusts over 40kt
with heavy rain. Will keep TS in the forecast for the next several
hours then going with VCTS for the remainder of the overnight period.
AUS, SAT, SSF should stay free of convection overnight but high
clouds from the west should keep things cloudy. Models are showing a
repeat of MVFR forming around midnight and did not adjust timing from
previous forecast. S and SE winds will remain gusty this evening,
over 25 kt in some locations, dropping off a bit overnight into
Sunday morning. Low clouds should break late morning Sunday but have
left out mention of SH/TS on Sunday due to uncertainty of location of
outflows over the current and expected convection overnight to our
far NW.
PREV DISCUSSION... /ISSUED 255 PM CDT Sat May 19 2018/
SHORT TERM (Tonight through Sunday Night)...
For the immediate short term, the focus is mostly out west where
isolated convection is expected to develop along another dry line
positioned west of Val Verde county. CAMs are having a hard time
pinpointing CI this afternoon, with many like the RAP/TTU-WRF/HRRR
keeping CI along the dry line farther west, but other CAMs including
the ARW/NMM initiate discrete cells near Del Rio after 21Z. Looking
at latest GOES VIS imagery, you can clearly see an inversion holding
steady over that region, and RAP forecast soundings show that won`t
change. However, NAM/GFS soundings DO erode the inversion.
Nevertheless, very strong mid level lapse rates, abundant MUCAPE
availability, and 30+ knots of 0-6 km effective shear check the boxes
for the potential for any CI to occur to be severe with large hail
potential and damaging straight line winds, especially given the very
dry low level atmosphere hydrometeors would fall into (inverted V
sounding). Slightly increased wording in the HWO to reflect these
concerns and went with a 40 PoP max out west with decreasing PoPs
farther east. It is worth noting that no CAM maintained convection to
the I-35 corridor overnight so this threat looks like it should be
confined to areas west.
The next question is the potential for convection farther north to
push southward and impact the area towards tomorrow morning. There
seems to be pretty good agreement that the front will stall well to
the north of the CWA, more along I-20. However, the concern would be
organized convection developing into an MCS and pushing southward.
There are indications in both the HRRR and WRFs that this would be
the case, but losing it`s parent lifting mechanism and being
primarily outflow driven, it should be sub-severe by the time it
reaches the Plateau, which is progged at roughly 15-18Z tomorrow.
This system will complicate pinpointing the best location for
potential re-development tomorrow afternoon and will likely rest on
the positioning of the remnant outflow from this system. Thus, PoPs
exist just about CWA-wide tomorrow, with a slight preference to the
north and west.
LONG TERM (Monday through Saturday)...
Scattered convection will be in the forecast through the weekend
before PoP chances decreases by Tuesday. Between 00Z tonight and 12Z
Tuesday, we are calling for about a quarter and a half inch of rain
across the area which will be quite nice for the region which is
mostly behind the monthly average to date.
Synoptically, a stubborn ridge axis over Mexico will hold off the
broad low out west from bringing its shortwaves close enough to our
area to bring meaningful rain to the area through the week next week.
Looks like eastern New Mexico and West Texas will stand to benefit
the most as a result. That low lifts north and rides along the
strengthening ridge axis by late week and should keep the region dry
through the weekend. Long range models bring a weak cold front
through next Saturday but moisture availability will be in question.
If a dry passage, fire weather may be the biggest concern next
weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 73 88 71 89 70 / 20 40 30 30 10
Austin Bergstrom Intl Airport 73 87 70 89 68 / 20 40 30 30 10
New Braunfels Muni Airport 73 88 71 89 69 / 20 40 20 30 10
Burnet Muni Airport 70 85 68 86 67 / 30 50 40 30 10
Del Rio Intl Airport 73 91 71 88 71 / 60 30 40 40 20
Georgetown Muni Airport 72 87 69 88 69 / 20 40 30 30 10
Hondo Muni Airport 73 90 71 89 69 / 40 30 40 30 10
San Marcos Muni Airport 73 89 70 88 69 / 20 40 20 30 10
La Grange - Fayette Regional 75 89 72 89 71 / 10 30 20 30 10
San Antonio Intl Airport 73 88 72 88 71 / 30 40 30 30 10
Stinson Muni Airport 75 89 73 89 71 / 30 30 20 30 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...09
Synoptic/Grids...Oaks
Area Forecast Discussion
National Weather Service Grand Forks ND
906 PM CDT Sat May 19 2018
.UPDATE...
Issued at 903 PM CDT Sat May 19 2018
Primary concern tonight will be frost potential with light to calm
winds and a cool airmass. Thin cirrus likely not a factor on
overnight lows. While most guidance a bit warmer than current
hourly temp curve, MET guidance (NAM MOS) is a few deg cooler.
Have extended advisory to the west a tier of counties...as
Fosston is generally a cool spot...and added Towner/Cavalier in
ND.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 317 PM CDT Sat May 19 2018
Temperatures and frost headlines will be the main issue for the
period.
Split flow with the main shortwave to our south over Nebraska and
the Northern Plains between the northern and southern branches.
Surface high pressure will be building into the CWA tonight. North
winds that have been very gusty today will diminish after sunset,
and many locations will become light and variable as the center of
the high settles over us. Cloud cover has exited the southeastern
counties, although a bit of cirrus has been approaching the
southwestern counties thanks to the upper low to our south.
Earlier runs of the GFS and NAM had some of this high level
moisture entering much of our CWA tonight, but the 12Z runs keep
most of it south. The most recent RAP has the current cirrus
decently handled and brings it briefly into our far south this
evening, but then dries out later tonight. Overall, think it will
be an ideal radiational cooling night with mostly clear skies and
light winds. Think that the far eastern tier will have the best
shot of seeing temperatures dropping below 36 degrees due to
slightly drier dew points upstream from that area. The HREF and
GEFS ensembles have some low probabilities of our eastern counties
getting down below 32 F. While that may be overdone considering
current dew points, think mid 30s are a good bet and put the
eastern tier in a Frost Advisory for late tonight. A few spots
in eastern ND could also dip down close to 36, but it looks to be
isolated and short lived.
After a chilly start tomorrow morning, the May sun will help highs
rise to the low 70s in most areas. Winds will be light and
conditions very quiet for Sunday.
.LONG TERM...(Sunday night through Saturday)
Issued at 317 PM CDT Sat May 19 2018
For Sunday night through Monday night, quiet and pleasant weather is
expected as high pressure remains situated over portions of the
Northern Plains and Great Lakes regions. Monday will bring light
winds, most sunny skies, and highs in the 70s.
Tuesday through Friday, zonal flow aloft transitions to southwest
flow as a closed low develops in the Southwest. This brings a more
active weather pattern with increasing moisture as southerly low
level flow develops for the middle to end of the week. Model
agreement is pretty poor as to when and where the forcing
mechanisms, upper shortwave energy and the primary surface low and
boundaries, develop. Thus have low confidence in the details of the
forecast for the second half of the week at this time. Rain chances
begin to move in on Tuesday and Wednesday, but these are not
widespread. Thursday to Friday looks to be the better chance for
most locations to see some wetting rain, with chances for thunder on
at least one of the two days as the main upper trough passes through
the Dakotas and Minnesota.
There is good agreement on temperatures next week. From Sunday night
through the middle of the week, expect a warming trend as drier
weather prevails and southerly flow develops for the Northern
Plains. By mid week, most locations will see summer like again.
Although there is uncertainty in the late week system, warmer
weather is likely to prevail based on proximity to the
aforementioned system and increasing thicknesses ahead of the system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 633 PM CDT Sat May 19 2018
VFR...NE winds will become light and variable tonight as sfc ridge
moves over area. By 12Z, look for lightest, most vrb winds to be
roughly along a Carrington (46D) to Bemidji (KBJI) line with winds
to south becoming more easterly and winds to north becoming more
westerly through the day. May see some early morning frost on
planes left out during the night, especially east of the valley.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Frost Advisory from 4 AM to 8 AM CDT Sunday for NDZ006-007.
MN...Frost Advisory from 4 AM to 8 AM CDT Sunday for MNZ006-008-009-
013>017-022>024-028-032.
&&
$$
UPDATE...Speicher
SHORT TERM...JR
LONG TERM...BP
AVIATION...Speicher
Area Forecast Discussion
National Weather Service Hastings NE
700 PM CDT Sat May 19 2018
.UPDATE...
Issued at 324 PM CDT Sat May 19 2018
Cancelled the flood watch. The main threat for flooding has passed
with only light rain expected across these areas tonight.
The South Loup River is forecasted to be in action stage through
the weekend and the Mud Creek is forecast to reach action stage by
early next week due to runoff across Custer County, but the
overall threat for flooding appears to be low at this time.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 217 PM CDT Sat May 19 2018
Overcast skies have prevailed across all but far southern and
southeastern Nebraska today. Meanwhile areas of clearing have
developed across Kansas, allowing for cumulus development and a
sharp gradient in instability across the area. The RAP forecast
shows around 2000j/kg of MUCAPE across southeastern portions of
the forecast area (Mitchell, Jewell, and southern Thayer
counties). Based on the CU field, I expect that most of the
development will be east of our forecast area, but if something
can develop in the aforementioned area, it could take advantage of
steep lapse rates and strong shear to produce large, damaging
hail. Even if storms develop, I expect them to move out of the
forecast area by 7PM.
A band of more persistent rain showers continue across the Sandhills
associated with the 500mb low, and we may see this band approach the
I-80 corridor across central Nebraska again tonight as the upper low
moves eastward. With little to no instability to speak of, no
thunderstorms are expected with this activity. A few showers may
linger into Sunday before coming to an end...especially in
northeastern parts of the forecast area.
On Sunday, skies will likely be slow to clear causing high
temperatures to only reach the 60s across the forecast area. For
reference, this is about 10 degrees below normal for this time of
year. Clearing skies should allow temperatures to fall into the mid
to upper 40s Sunday night.
.LONG TERM...(Sunday night through Saturday)
Issued at 217 PM CDT Sat May 19 2018
This cooldown will be relatively short-lived though. High
temperatures are expected to return to the mid 70s to near 80
degrees on Monday as we move back into southerly flow near the
surface. Chances for thunderstorms return to the area Monday
night thanks to warm air advection and a 35-40kt low-level jet in
the area.
Off and on chances for thunderstorms then continue each day through
Friday as a deep upper low slowly moves out of the southwest US,
across the Rockies and into the northern Great Plains. Details and
timing of storms is still pretty uncertain, so no reason to make
any changes from the model consensus at this point.
High temperatures Tuesday through Friday are expected to reach the
mid to upper 80s, possibly making a run towards the low 90s for
portions of the area on Thursday and Friday.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 621 PM CDT Sat May 19 2018
Plenty of MVFR or lower stratus expected to stream across the
terminals for the next 24 hours. Expect CIGS to gradually lower to
near 300 feet overnight...with a few showers also possible
through the overnight hours. In addition...could see some light BR
develop overnight...resulting in prevailing MVFR VSBYS...but
limited VSBYS to 5 SM at this time as wind direction is not
favorable for dense fog and winds will only relax to around 8 KTS
overnight. For tomorrow...cloudy skies are expected through the
afternoon hours...with IFR CIGS in the morning gradually
improving to near VFR levels by late afternoon as the responsible
system begins to exit the region.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Mangels
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Rossi
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1052 PM EDT Sat May 19 2018
.SYNOPSIS...
A slow moving low pressure system will move away from our
forecast area Sunday, however the atmosphere will remain very moist
for the next few days and keep a rather high chance of showers and
storms each afternoon and evening.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1050 PM EDT: Only minor tweaks needed for this update as the
overall near term forecast remains on track. A Flash Flood Watch
remains in effect for portions of the area through midnight.
Latest radar imagery continues to depict isolated showers and
thunderstorms moving across the FA this evening, and while they do
not look overly impressive structure-wise, their packing quite a
punch, bringing heavy downpours to areas across the NC mountains
which continue to have flooding concerns. Overnight, am still
expecting the coverage of shower/thunderstorm activity to become
minimal, though latest trends seem to be possibly lining up with
recent HRRR run, showing increasing activity towards the I-77
corridor before activity wanes. Aside from this activity, expect
lower cloud cover increasing overnight with low temperatures dipping
into the 60s.
Otherwise, an upper trough will continue to lift north and deamplify
as its axis crosses the CWFA this evening. This is a result of the
large subtropical ridge over the North Atlantic ridging westward
into the Southeast U.S. for Sunday. The low-level and mid-level flow
will briefly turn out of the NW in the wake of the trough, then
become very light. Not expecting much change in air mass, but
guidance generally agrees on slightly drier air and less convective
coverage than last couple days. Very weak shear and SBCAPE of 1500-
2000 J/kg should support pulse convection with a non-zero severe
threat tomorrow. Highs will climb into the 70s mountains and mid 80s
piedmont on Sunday under partly to mostly cloudy skies.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 215 PM EDT Saturday: Subtropical anticyclone remains remains
anchored off the southeast coast through the period, but it does
weaken slightly and slowly drift southward. A weak upper low starts
the period along the Florida panhandle then opens and slowly drifts
northward into the southern Appalachians through the period. This
keeps a south to southwest low level flow across the area. The
guidance shows instability each day, but weak overall as some low to
mid level warming keeps CAPE values on the low side. The guidance
has also trended away from the drying mid levels keeping surface
delta theta-e and DCAPE values in check. The pattern still looks to
be mainly diurnal in nature, but severe chances have diminished.
Heavy rainfall is possible with any thunderstorm and FFG values will
be low so the flood threat will continue, but hopefully not as
widespread as in previous days. Highs a few degrees above normal
Monday fall to near normal for Tuesday. Lows around 10 degrees above
normal drop a couple of degrees.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 235 PM EDT Saturday: Upper ridging builds in from the west
through the period and merges with the subtropical anticyclone off
the southeastern coast. At the surface, high pressure remains over
the area but does become suppressed as a front drops toward the area
and stalls. This keeps a warm and moist airmass over the area
through the period. However, with the upper ridging in place,
instability is relatively weak due to warm mid level temps. Still,
expect mainly diurnal convection through the period. Severe chances
look to be on the low side with the weak instability, shear, and
little in the way of DCAPE. PW values are relatively high, so
isolated heavy rainfall is possible. The wet antecedent conditions
will keep a flood threat in place through the period. Lows remain
nearly steady around 10 degrees above normal while highs remain
nearly steady around 5 to 10 degrees above normal.
The wild card for this period is the potential tropical or sub-
tropical system that develops over or near the SE CONUS by the end
of the period. Guidance has been insistent that something will form
and be near the SE CONUS or our area by Saturday. Of course, it is
way too early to know if this will directly impact our CWFA.
However, given the rainfall our area has recently received, this
type of system could cause significant problems if it directly
impacted our weather. For now, worry more about the near and short
term convective threats, but keep an eye on the forecast for next
weekend.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Mainly low-end VFR cigs prevail this evening,
as isolated showers and thunderstorms continue to move across the
area, which could still potentially create a brief period of
MVFR cigs/visibilities to any of the terminals over the next few
hours, especially in heavier downpours. Overnight, as flow
veers to the west, expect stratus to develop, bringing the
potential for IFR cigs and patchy MVFR fog as well. After
daybreak, expect fog to quickly dissipate with a gradual
improvement of cigs to VFR. Isolated showers and thunderstorms
will be possible once again, though coverage is expected to be
less than the trend over past few days. Aside from varying wind
direction with any convection or outflow boundaries, expect SSW
5 to 10 kts through the valid TAF period.
Outlook: An unsettled weather pattern will continue into early next
week with isolated to scattered SHRA/TSRA and possible flight
restrictions each day.
Confidence Table...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT High 87% High 81% Med 70% High 100%
KGSP High 89% Low 51% High 94% High 85%
KAVL Med 67% High 85% High 96% High 100%
KHKY High 89% Med 66% High 88% High 100%
KGMU High 96% Med 66% High 94% High 85%
KAND High 98% Med 66% High 90% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Flash Flood Watch until midnight EDT tonight for NCZ033-049-
050-053-064-065-501>510.
SC...Flash Flood Watch until midnight EDT tonight for SCZ002-003.
&&
$$
SYNOPSIS...SBK
NEAR TERM...ARK/SGL
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...SGL
Area Forecast Discussion
National Weather Service Wilmington NC
1202 AM EDT Sun May 20 2018
.SYNOPSIS...
Scattered showers and thunderstorms can be expected much of
the upcoming week, as humid air of tropical origin remains
across the region. Rain chances will increase late Wednesday
into Thursday, as a cold front slowly crosses the coast. High
pressure to the north, may bring a brief drying trend Friday
and Saturday.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 845 PM Saturday...The tropical moisture plume is currently
getting shunted westward. This a result of Bermuda high
pressure also ridging westward and onshore across South
Carolina. Will re-orient this plume, via the latest edited
hier Pops channel, across coastal SC and and into NC. The HRRR
is indicating a nocturnal increase in convective activity along
this plume overnight into Sun daylight morning hours that could
affect the eastern FA with additional pcpn. The threat for
widespread heavy rain is over with but still could see isolated
heavier showers later overnight. Tonights lows have been
tweaked hier by 1 to 2 degrees, especially at the coast where
70s dewpoints will be common.
Previous.......................................................
As of 3 PM Saturday...Tropical moisture will continue streaming over
the region into the evening, maintaining high rainfall chances for
the next several hours. Widespread showers are likely with isolated
embedded thunderstorms into the evening hours. Later this evening a
subtle westward shift in the surface and mid-level ridge off the
Southeast coast will disrupt the tropical moisture feed. It will
also lead to an increase in mid-level subsidence over the area and
shunt the vorticity stream farther west. These factors should bring
about a 24 hour or so period of decreasing precip chances despite
precipitable water levels still running between 1.6 and 1.8 inches.
South to southwest flow overnight will weaken somewhat but boundary
layer winds will remain 15 to 20 kt. This should keep fog from being
an issue in most areas overnight.
Drying trend continues on Sun although showers and thunderstorms
will remain a possibility, especially in the afternoon. Precip
chances drop into the chance range Sun with the best chances looking
to be along the SC coast. Weak low level convergence and some weak
divergence will support some convection in this area. Across the
forecast area there could be breaks of sun, which could produce
differential heating boundaries as well as help to increase diurnal
instability. Any storms that develop will continue to have the
potential to produce very heavy rain for brief periods of time. Warm
cloud layer depth will be around 11k ft. While not as high as today,
this is still sufficient to produce very heavy rainfall. Slow storm
motions will increase the flooding potential on Sun, especially in
the afternoon. Forecast soundings drop storm motion under 10 kt by
SUn afternoon. Highs will be in the lower 80s, but mid 80s will be
possible with breaks of sunshine.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...Subtle improvement forecast for the
beginning of the week. Persistent Bermuda High will expand westward
causing the weak upper low to the west to weaken. This occurs in
conjunction with advection of drier air from the east, with PWATs
dropping below 1.5 inches for the first time in several days. These
two features combined with at least weak subsidence as the ridge
expands, will bring a decrease in shower activity during the short
term. Southerly, tropical, flow will still be capable of producing
convection, mostly diurnally forced inland with nocturnal increase
possible at the coast, but total coverage will be less than the past
several days. Less cloud cover and the increased thicknesses will
allow highs to climb into the mid 80s inland, low 80s near the
coast, on Monday. Mins both nights will remain well above normal,
around 70 as the humid airmass persists.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...Guidance differs considerably in the
extended with how much rain may fall during the middle of the week,
leading to lowered confidence in this part of the forecast. The GFS
seems to be the wettest Tue-Thu, while the CMC/ECM are much drier
across the Carolinas. The synoptic setup is comparable through each
model, with the key difference being the timing and duration of
moisture return as model PWATs vary. The GFS may be a bit too wet,
but deserves at least some credence due to the pattern remaining
similar to the past week, and the moisture tap from the tropics
remaining in place. Will maintain CHC POP Tue-Thu, with Tue likely
being the driest of the 3, and Thursday potentially the wettest
thanks to a cold front which will drop into the region and serve as
a focus for convection. Regardless of how many showers develop,
there will be a good chance for showers/iso tstms each day Tue-Thu
with temps slightly above climo for highs, and well above for lows.
Front will weaken and dissipate friday which should lead to lowered
POP chances as high pressure tries to build into the region for at
least one day. However, this drier air may again be short-lived. All
extended models suggest a low pressure of tropical origin will
develop near the Caribbean and move slowly in that region. This will
again send a plume of tropical moisture towards the Carolinas
bringing a return to unsettled and humid conditions with continued
slightly above normal temperatures.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
As of 00Z...Stagnant tropical pattern will continue through the
period though the tropical connection through FLA and beyond looks
to be weakening on satellite and radar attm. While there still is
potential for on and offer showers through the period, activity
should be more off and on than it was today. Even though MVFR
conditions are expected to dominate through the period intermittent
IFR is possible tonight with intermittent VFR possible after
sunrise.
Extended Outlook...Periods of MVFR/IFR cigs/vsbys associated with
tropical type showers and tstorms through the period. Activity will
be more numerous along the coast pre-dawn hours thru mid-morning
hours each day, then translate to the inland terminals midday-early
evening. Possible break in the action on Mon, but rain returning Tue
and Wed. Finally an air mass change on Thu.
&&
.MARINE...
NEAR TERM /THROUGH SUNDAY/...
As of 845 PM Saturday...Extended the SCA from midnight to noon
Sunday. The SE-S winds that extend across a large fetch from
well upstream to and across the local waters, has resulted in
significant seas in the 4 to 7 foot range with 8 to 9 second
periods dominating. The sig. seas, power wise via spectral
density plots, are largely made up of the SE ground swell
exhibiting 8 to 9 second periods due to the spoken fetch. It
will take a bit more time for seas to lower even though winds
across the local waters remain below SCA thresholds. Coverage of
nocturnal showers and isolated tstorms will increase during the
pre-dawn hrs and persist into the daytime hrs. Vsby will
temporary lower to 1 nm or less within the heavier pcpn.
Previous......................................................
As of 3 PM Saturday...Small Craft Advisory remains in effect for
all zones this afternoon. Current hazard runs through midnight
and latest wind/wave forecast meshes well with this. The Bermuda
High starts to expand west this evening, which weakens the
gradient and helps shift winds to more of a southerly direction.
The decreasing wind speeds should allow seas to fall under 6 ft
late tonight. Winds become more southwest during Sun, but
speeds will be under 15 kt. Seas 3 to 6 ft through tonight will
drop to 3 to 5 ft after midnight and by the end of the period
will be 2 to 4 ft.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...High pressure offshore will continue through
early next week although with slightly stronger ridging in place.
This will persist S/SW winds across the waters, but a weak gradient
will keep speeds at around 10 kts. These light winds will allow a SE
swell due to long duration fetch around the offshore high to be the
predominant wave group, with seas of 3-4 ft expected throughout.
LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...Continued high pressure offshore will drive
S/SW winds of 10-15 kts across the waters Tue and Wed. Early on
Thu, a weak front will drop into the area turning winds to the W/NW
Thu morning, before this front dissipate leaving a weak gradient and
variable winds through the end of the period. Seas of 3-4 ft will
continue Tue/Wed thanks to a SE swell and SW wind wave. However, as
the winds ease and become variable Thursday at the same time the
swell begins to deamplify, wave heights will drop to around 2 ft
late.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until noon EDT Sunday for AMZ250-252-254-
256.
&&
$$
SYNOPSIS...MJC
NEAR TERM...DCH/III
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...RAN
Area Forecast Discussion
National Weather Service Lincoln IL
1051 PM CDT Sat May 19 2018
.UPDATE...
Issued at 850 PM CDT Sat May 19 2018
Latest surface analysis indicates a weak frontal boundary lying
across our far northern counties with the latest ILX objective
analysis indicating some persistent low level convergence along
this feature. However, not much has developed early this evening.
A large complex of storms moved across south central Missouri
late this afternoon into far southern Illinois with the outflow
boundary well off to our south at this hour. Another complex of
storms has moved northeast out of southwest Missouri but as it
encountered the much more stable air in place west of St.Louis
early this evening it has weakened with cell propagation more
to the east and southeast into a more unstable air mass. Due
to the two clusters of storms moving across south central Mo,
into far southern IL, quite a bit of convective inhibition in
place, so will do a little work on the POP chances across the
forecast area overnight.
The lastest High Resolution Rapid Refresh models continue their
trends from late this afternoon when they were suggesting not
much, if any strong convection was going to work its way northeast
into the area late tonight. Both the HRRR and HRRR-X suggest a
dissipating band of convection moves in towards Midnight and then
another cluster of storms tracks northeast out of Missouri into
our area Sunday morning. Just what affect, if any, this will have
on our convection chances tomorrow afternoon remains uncertain at
this point. If we see very little organized storm activity overnight,
we will be primed for strong to severe storms tomorrow afternoon
over at least our central and southern counties. If the Sunday
morning band of storms is more organized than currently forecast,
than our atmosphere may take longer to reload tomorrow afternoon
in addition to trying to determine the best location where storms
would fire. For now, will not make any significant changes to
Sunday`s outlook and make some adjustments to the overnight POPs
based on current trends this evening. The updated ZFP should be
out by 9:15 pm.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 310 PM CDT Sat May 19 2018
Weak upper wave moving off to the northeast this afternoon while
another wave over the Central Plains is triggering a convective
complex for the afternoon. Some showers and thunderstorms from an
old outflow boundary to the southwest will move across southern
IL later this evening, bringing some scattered thunderstorms. Main
concern for widespread thunderstorms will be in the overnight
hours as energy from that wave ripples downstream. Models are
inconsistent with how much of the wave moves vs weaker DPVA into
the region. Seeing CAMs vary from little to no activity...to
closer to a weakening QLCS by morning. With the uncertainty, the
forecast remains vague, carrying the threat for overnight severe
threat at marginal in the Day One from SPC. Atmosphere decoupled
in the overnight, MUCAPEs remain in the low to moderate category
and the bulk shear is generally less than 20-30kts in the NAMNest.
Given the elevated convection in the overnight hours, after 12Z,
the region is clearing in most model solutions. HRRR is slowing
slightly in the progression of the precip and may end up delaying
the clearing as well in subsequent runs. Surface low/boundary
slips through Central IL tomorrow, with veering winds through the
day. More northerly winds persist north of the boundary after
sunrise, resulting in temps north of I-74 tapping into far cooler
air and highs struggling to reach into the low to mid 70s. Whereas
the southern half of the state in the mid to upper 80s. Along with
plenty of llvl moisture, south of I-70 will see heat indices in
the low 90s tomorrow afternoon. Another round of thunderstorms
will also threaten the region, with the severity of the storms in
the afternoon very dependent on the evolution of the overnight
storms and projected recovery of the atmosphere south of the
front. Lacking deep layer shear, and mediocre lapse rates, any
areas of strong CAPE will still add an element to the afternoon
thunder increasing threat of damaging wind gusts/large hail.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 310 PM CDT Sat May 19 2018
Models having a really hard time evolving one MCS disparate from
another beyond Sunday. GFS has another complex of storms Sunday
night, whereas the ECMWF is still moving the afternoon storms off
to the east. Either way, it`s safe to say that the active pattern
will likely continue until a weak upper low clears the region, not
anticipated until Mon night/Tuesday. This parallels when the
blended forecast dries out for a while, at least until the latter
portion of the week. The region remains close to the axis of the
upper ridge, with weak NW flow...slowly transitioning to more
southwesterly flow. Either way, the midlevels maintain access to
the warmer temps of the swrn CONUS through the end of the
forecast, keeping temps about 10F above seasonal norms.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1045 PM CDT Sat May 19 2018
Mainly VFR conditions to start this forecast period with and then
a low probability for a period of MVFR cigs Sunday morning in the
12z-16z time frame, especially if precipitation occurs late
tonight into Sunday morning. The large cluster of storms to our
south will remain well south of the TAF sites overnight. However,
additional showers and thunderstorms may move northeast into the
area late tonight and especially during the morning hours of
Sunday. However, coverage at this point continues to be limited
so will hold on to the VCTS until we get a better timing on any
storms that may affect one of the TAF sites. Surface winds for the
rest of tonight will be light southeast to south but will tend to
back more into an easterly direction in PIA and BMI. Easterly flow
will continue at PIA and BMI on Sunday with speeds of 8 to 13 kts,
while at SPI, DEC and CMI we look for winds west to northwest by
tomorrow afternoon and then into a northerly direction by Sunday
evening.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Smith
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
824 PM CDT Sat May 19 2018
.UPDATE...
Issued at 823 PM CDT Sat May 19 2018
Updated to increase and decrease some rain chances.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 330 PM CDT Sat May 19 2018
The primary forecast challenges through Sunday afternoon revolve
around the upper low centered over the Sandhills and the cold front
dropping through the state. Rain showers (some heavy) have affected
the forecast area for the past couple days with widespread 3-4"
totals as of Saturday early afternoon. The areal Flood Watch
continues through 00z for portions of SW Neb and the river Flood
Warning for the N.Platte River continues through Tue night.
This evening and tonight... Near term solutions (HRRR/RAP/HREF) have
been portraying this system fairly well, and continue the
deformation band into the early evening across the Sandhills. As the
upper low slowly treks through the area, some regeneration of
showers is expected SW Neb (and some signs have already begun
showing up on satellite and radar as of 20z). RAP mesoanalysis
indicates the continuous moisture flow from the southern Plains and
near-record PWAT. Broad isentropic upglide shown at multiple theta
levels as well as mid-level fgen will maintain precip potential.
Maintained QPF through 06z at 1/4 to 1/2", mainly across the
Sandhills. Removed thunder mention as CAPE and effective shear are
essentially non-existent and sfc temps struggling to reach the 50s.
Temp-wise, cooled overnight lows slightly but kept near the top end
of guidance due to thick cloud cover. Forecast lows range from upper
30s panhandle to mid 40s north central. No frost headline expected
due to ongoing precip and low confidence in reaching lower/mid 30s.
Gusty north winds also wane through the evening as the surface
pressure gradient relaxes and H85 flow backs off.
Sunday... Few remaining showers possible for central Neb due to the
vicinity of the low/enhanced forcing, but moisture isn`t nearly what
it was the past couple days. Isentropic upglide weakens and
transitions to downglide by the afternoon. Overall, looking at
partly to mostly cloudy skies and continued cool conditions. Went
with a general MAV/MET/ECS blend for max temps, resulting in lower
60s (and slightly cooler north central), which is about ten degrees
below normal. Seems reasonable given aforementioned cloud cover,
north winds, and H85 temps under 10C.
.LONG TERM...(Sunday night through Saturday)
Issued at 330 PM CDT Sat May 19 2018
The next chance of thunderstorms is Monday evening. Both the NAM and
GFS indicate favorable shear and instability for some severe weather
potential. SPC has not outlooked wrn or ncntl Neb for severe weather
but Bufkit, the MET, MAV and ECS guidance, the SREF and the CIPS
analogs suggest some level of potential. SPC will review the severe
weather potential for Monday, tonight.
Another severe thunderstorm opportunity develops Wednesday
associated with an upper level low lifting through the nrn Rockies.
This should produce favorable winds aloft and moisture will be in
place with dew points in the mid 50s to lower 60s. Note that some
sort of thunderstorm chance is in the forecast Monday through Friday
and this is consistent with return moisture, strong daytime heating
and the potential for nocturnal forcing associated with a low level
jet. Monday and Wednesday would appear to be the best chances. This
is based on a local severe weather ensemble procedure suggesting
Monday as "likely" and Wednesday and Thursday as "possible".
Forecast highs rise into the 70s Monday and 80s Tuesday and beyond.
The GFS and the model consensus would suggest drier air moves in
Thursday. This is the result of a Pacific cold front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 648 PM CDT Sat May 19 2018
Widespread light rain will continue to diminish ian area and
intensity over western Nebraska tonight. Light north winds will
continue over northern Nebraska qhile stronger northerly flow will
continue over southern Nebraska. Mvfr conditions with occasional
ifr ceilings are possible over southern Nebraska through Sunday
morning while vfr cigs are expected over the north.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Power
SHORT TERM...Snively
LONG TERM...CDC
AVIATION...Power
Area Forecast Discussion
National Weather Service Midland/Odessa TX
502 PM CDT Sat May 19 2018
.DISCUSSION...
See aviation discussion below.
&&
.AVIATION...
Prevailing VFR conditions are expected at the west Texas and
southeast New Mexico terminals the next 24 hours. A cold front
across the northern Texas Panhandle will move south overnight
into the central Permian Basin by sunrise and then into the
mountains by Sunday afternoon. Prob30 thunderstorms with MVFR
CIGS will be possible along and behind the front at most
terminals beginning 20/09z.
&&
.PREV DISCUSSION... /issued 218 PM CDT Sat May 19 2018/
DISCUSSION...
Hot conditions are present again across the area this afternoon with
a dryline slowly pushing east across the central Permian Basin. The
latest hi-res models offer a plethora of solutions as to convective
initiation this afternoon and evening. The HRRR/RAP show showers
and storms developing along the dryline in the Permian Basin over
the next few hours while other models show convective development
well to our north and east. Will lean toward the HRRR and RAP as
it places the dryline fairly close to where it is now and has
performed well over the past few days. Storms could become severe
with damaging winds and large hail given steep lapse rates and a
dry subcloud layer.
At the same time a cold front is moving slowly south across the TX
Panhandle this afternoon. Convection will develop along this
boundary this evening and aid in pushing the cold front south. Most
of the models show an MCS forming and moving south along with the
cold front arriving in the northern Permian Basin around sunrise.
There is much disagreement in the models with the evolution of this
system and rainfall amounts are extremely variable. Best guess is
that the heaviest rain will fall across the northern and eastern
Permian Basin through the morning hours. Rain should dissipate by
mid morning with the cold front likely moving to the Pecos River or
eastern slopes of the higher terrain by afternoon. Storms are then
expected to redevelop in the Davis Mountains south to the Presidio
Valley Sunday afternoon. These storms could again be severe given
strong instability and steep mid level lapse rates.
Periods of thunderstorms will possible through at least mid week as
occasional disturbances move across the area within southwest mid
level flow. Some of the storms could be severe and heavy rain may
become a possibility if rain falls over the same locations
multiple times. Upper ridging looks to build in by the end of the
week with rain chances lowering and the heat ramping back up.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 71 83 65 85 / 60 60 50 50
Carlsbad 56 84 62 87 / 10 40 50 50
Dryden 70 87 67 86 / 10 50 50 40
Fort Stockton 69 86 65 86 / 10 50 50 40
Guadalupe Pass 61 79 62 82 / 0 40 50 40
Hobbs 62 80 61 82 / 50 50 60 50
Marfa 55 84 55 86 / 10 50 50 30
Midland Intl Airport 70 83 65 85 / 50 60 50 50
Odessa 71 83 66 85 / 40 50 50 50
Wink 69 87 65 87 / 10 50 50 40
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
99/99/12
Area Forecast Discussion
National Weather Service Melbourne FL
1005 PM EDT Sat May 19 2018
.UPDATE...
A steady light rain with embedded moderate to heavier showers
continues mainly across the S/E half of the CWA/MAOR as a deep
southerly flow of PWAT rich air continues to stream northward over
the peninsula. Divergent flow from the negative tilt H25 trough over
the eastern GOMEX will continue to provide sufficient forced ascent
to produce widespread light to occasionally moderate rain, with a
few heavier showers along the coast. Minor nuisance flooding will be
possible in poor drainage areas overnight where persistent rain and
embedded heavier showers continue to fall. Thunder should be limited
to the Atlantic and Gulf Stream waters during the nocturnal marine
instability maximum. Made some minor adjustments to POPs, mainly
across the north/interior given current radar trends.
&&
.AVIATION...Widespread MVFR VSBYs in -RABR with spotty IFR tough to
time, but most likely along the MLB-SUA corridor. CIGs VFR to
occasional MVFR in precip.
&&
.MARINE...Wind flow remains rather disturbed by widespread precip
and embedded convection, however synoptic flow supports 10-15KT
increasing to 15-18Kt later tonight. Current seas 3-4FT near shore
and 4-5FT well offshore, progged to build slightly late tonight and
moreso on Sunday, reaching 6FT at times.
&&
UPDATE/AVIATION...Cristaldi
RADAR/IMPACT WX...Bragaw
&&
.PREV DISCUSSION... /issued 340 PM EDT Sat May 19 2018/
...High Rain Chances Will Continue through Sunday with Locally
Heavy Rainfall...
Sunday...Diehard mid/upper level trough over the eastern Gulf of
Mexico and stout Atlantic high pressure ridge will maintain a deep
southerly wind flow and focus a "firehose" of moisture into the
Florida peninsula. A slight negative tilt of the upper trough will
also produce divergence aloft. Breezy low level flow promoting
convergence will exist between the Atlantic ridge and a weak
inverted trough sliding across the southern peninsula into the
eastern Gulf. These ingredients will continue to keep PoPs high with
a threat of heavy rain.
Will keep rain chances at 60-80% for both periods. The greatest
threat for heavy rain amounts should be along the coast,
especially the Treasure Coast. The clouds and rainfall will keep
max temps on Sunday suppressed below normal, mainly lower 80s.
Previous Discussion...
Mon-Sat...The Atlantic ridge axis will remain the dominant weather
feature with a moist south to southeast flow keeping rain chances
above normal (40 to 60 percent) supporting mainly daytime showers
and storms. The ridge axis is forecast to gradually shift southward
and weaken during mid to late week as a trough develops over the
Southeast US. A slight reduction in the deep moisture will allow a
little more sunshine and produce Max temps mainly in the mid 80s but
remaining humid. Both GFS and ECMWF show an increase in tropical
moisture over the area late in the week but both operational
solutions differ significantly on the placement of a potential
tropical disturbance.
&&
.AVIATION...Scattered showers and thunderstorms will continue
through the late afternoon from KTIX-KISM northward. These storms
are capable of producing gusty winds, and IFR conditions with
visibilities around 2 SM. Areas from KMLB-KSUA will see moderate
to heavy rain. After 19/20Z thunderstorm activity should move west
of the area, and a large area of moderate to heavy rain will be
affecting all the terminals. Periods of IFR/MVFR visibilities are
likely with any heavy rainfall, so I will introduce TEMPO groups
into the TAFs later this afternoon to account for this. Conditions
will begin to improve from south to north after sunset, although
a few lingering showers are possible across the area. There is the
possibility of MVFR CIGs across the interior tonight from 20/06Z-
12Z, but probabilities are too low to include in TAFs at the
moment. Overnight, the HRRR and local WRF models are indicating
showers and perhaps a few thunderstorms will affect the Treasure
Coast and Brevard County. There is still too much uncertainty
regarding the exact timing and strength of these storms to include
a TEMPO group in the TAFs. However, I did include VCSH for all
coastal terminals through Sunday morning as an early indication of
possible rain/storms. Otherwise, expecting mostly VFR conditions
after the rain diminishes.
&&
.MARINE...
Tonight-Sunday...Conditions will continue bad for small craft
operation. First, the gradient wind from the southeast will be near
15 knots and 15-20 knots offshore, creating seas 3-5 feet and up
to 6 feet offshore. Second, very moist air will continue to produce
periods of showers and a few storms.
Monday-Thursday...The axis of the Atlantic high pressure ridge will
stay north of the waters into Wed. The models show this will
continue to produce a breezy southeast wind flow and rather agitated
seas at least through Tue. By Thu, the ridge axis is forecast to
settle into the waters, which should knock winds down closer to 10
knots. Moisture is forecast to diminish early next week, especially
starting Tue, so periods of showers with isolated storms should
become less frequent.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 70 80 71 82 / 60 70 40 60
MCO 71 80 70 84 / 60 80 40 60
MLB 73 82 74 82 / 70 70 50 60
VRB 72 82 73 83 / 80 70 50 60
LEE 70 80 70 85 / 60 80 40 60
SFB 70 79 70 83 / 60 80 40 60
ORL 70 78 70 83 / 60 80 40 60
FPR 72 82 73 83 / 80 70 50 60
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Area Forecast Discussion
National Weather Service Norman OK
710 PM CDT Sat May 19 2018
.AVIATION...
Widely scattered showers and thunderstorms are expected
to become more numerous this evening and overnight. The
stronger storms will be capable of lowering visibility
to less than 1 mile and produce wind gusts in excess of
45-50 knots. Perhaps the more significant storms will
impact the terminal sites around LAW and SPS.
By 12Z most of the showers and storms should be east and
south of most of the terminal sites. A cold front across
northwestern Oklahoma, will move slowly south tonight before
stalling on Sunday. During the day Sunday, mainly VFR conditions
are expected.
&&
.PREV DISCUSSION... /issued 327 PM CDT Sat May 19 2018/
DISCUSSION...
Strong to severe thunderstorms have formed over the past
hour, mainly across north central and southwest Oklahoma. An
outflow boundary that lifted northward from central Oklahoma
earlier this morning, has been augmented by afternoon convection.
Overall, additional strong to severe storms will continue to
form generally near and ahead of a cold front that extends from
the Texas Panhandle into northwestern Oklahoma. Several HRRR runs,
predict storms will eventually evolve into a thunderstorm complex
or two. One may develop from western north Texas and southwest
Oklahoma and move into central/north central Oklahoma, while
another may evolve from the Texas Panhandle and impact
southwestern Oklahoma and north Texas. If this occurs, the over
hazard will likely be strong damaging winds with some hail. In the
meantime, large hail and strong outflow winds are expected.
Depending on storm evolution tonight through Sunday morning,
little thunderstorm development may occur Sunday afternoon and
evening.
Late Sunday into Monday, a trough/low is expected to move across
southern parts of the West Coast. Weak height rises are expected
over the southern plains with rather weak southwest flow,
especially the eastern half of Oklahoma. Although showers and
thunderstorms will be possible they will be rather slow moving and
mainly not severe.
As the trough lift northeast Tuesday into Wednesday, additional height
rises will occur and the overall flow across Oklahoma and north
Texas will be very weak for late May. Shower and thunderstorm
chances will be rather low.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 66 77 63 82 / 90 30 20 30
Hobart OK 62 76 62 83 / 80 30 20 30
Wichita Falls TX 67 79 66 84 / 80 50 20 30
Gage OK 54 74 58 82 / 60 20 20 20
Ponca City OK 61 74 59 82 / 80 20 10 30
Durant OK 69 83 67 86 / 30 30 20 30
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
924 PM CDT Sat May 19 2018
.UPDATE...
Issued at 924 PM CDT Sat May 19 2018
One area of convection has exited to the east of the area, but
another one is approaching from the west. Latest radar imagery
indicate that outflow is pushing away from the active convection
along the northern portions of the line and the southern end of
the line is really slowing down. Given that our area is thoroughly
worked over there really isn`t much reason to expect this line to
reach our region as more than a band of weakening showers, but
will keep a slight chance of thunderstorms going just to be safe.
For now the late evening hours should be dry over our region.
Also made some adjustments to temperature and dewpoint trends
through the night as the previous convection has depleted
dewpoints a bit more than previously expected in the west.
UPDATE Issued at 737 PM CDT Sat May 19 2018
Updated aviation discussion.
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 403 PM CDT Sat May 19 2018
Tough mesoscale situation to determine eastern extent and limit of
convection for the remainder of the afternoon and this evening. In
short, leaned closer to the ESRL HRRR/13km RAP guidance to reflect
the eastern limit of thunderstorm activity through 7 pm CDT. The
local mesoscale environment along and ahead of the convective
lines over east central Missouri may persist further east near
Interstate 57 by 6-7 pm before collapsing with the loss of
insolation and weak/moderate shear. The 13km RAP Mesoscale
Convective System (MCS) maintenance probabilities still suggest
significant weakening between 23z-01z, so will hold with the
current forecast of thunderstorms limited to mainly along and west
of the Mississippi River in southeast Missouri and over the
Purchase area of west Kentucky through sunset.
To complicate things even more, the stable boundary layer from the
fog/low clouds over southeast Missouri into southern Illinois
has created differential heating zone over the area, helping to
maintain isolated convection into northern sections of southeast
Missouri and then again in the lower delta regions of southeast
Missouri and the Bootheel onward to the border counties of west
Kentucky and west Tennessee.
More intense LAPS surface theta-e gradient across northwest
Tennessee edging into the southern Purchase area of west
Kentucky. A broader and much weaker theta-e axis extends from the
Land Between the Lakes northward into southeast Illinois. Although
there is good surface CAPE (2000-2500 j2/kg2) and weak helicity
(100 m2/s2 or less) in this area, thermal profiles (better lapse
rates) are lacking and may not support much more than showers
through mid-evening.
As the boundary layer stabilizes, anticipate most of the moisture
and instability will become elevated and shifted to the northern end
of the WFO PAH forecast area, where low level moisture convergence,
stretching, and lift is forecast to be maximized. Therefore,
significantly reduced PoPs across the entire WFO PAH forecast area
during this evening, then increase PoPs near a weak developing
surface trough in extreme western sections of southeast Missouri,
then along the I-64 corridor after midnight and through daybreak on
Sunday near an impressed warm front.
Although not favorable, there may be an outside chance that the
convection overnight may generate enough of a balanced cold pool
for MCS development well south into the WFO PAH forecast area. It
will bear monitoring early Sunday morning.
Sunday will bring significant potential CAPE of 3000-5000 j2/kg2
even during the morning hours in the warm sector south of the
convective activity expected along the I-64 corridor. The low and
mid level shear ranges from 10-30 knots, with the highest values
obviously near the convection on Sunday. Between thunderstorm
outflows from the north and larger scale isentropic lift,
anticipate a slight chance of showers and thunderstorms area wide
by late morning and through midday. This activity should continue
through the afternoon and become enhanced as a weak shortwave
glances the area from the northwest with the primary wave going
into Wisconsin and the Great Lakes region.
With the WFO PAH forecast area moving into a faster southeasterly
flow aloft and weak moisture advection, small non-diurnal chances
for rain will exist the rest of Sunday through Monday.
.LONG TERM...(Tuesday through Saturday)
Issued at 403 PM CDT Sat May 19 2018
There remains a mention of mainly diurnal showers and
thunderstorms across the WFO PAH forecast area through the remainder
of next week. However, continue to have low forecast confidence
for any widespread precipitation Wednesday through Friday, as high
pressure dominates at middle and upper levels of the atmosphere.
At this time, looked for opportunities to lower rain chances
across the WFO PAH forecast area, especially Wednesday through
Friday.
&&
.AVIATION...
Issued at 737 PM CDT Sat May 19 2018
VFR cigs are forecast for the 24 hour TAF period. Small dewpoint
depressions will compete with southwesterly winds just off the
surface to encourage or inhibit fog overnight. At this time, though
there seems to be some possibility of fog mainly west of the MS
River around sunrise, confidence was not high enough to include in
the TAFs. Light and variable winds overnight should increase to
under 10 knots out of the southwest Sun. Scattered shower and tstm
activity will probably be around north of I-64 after midnight,
followed by scattered activity during the day, more so in the
afternoon. Brief reductions in vsbys and gusty winds are possible
just about anywhere during the day Sun.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...DRS
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...DB
Area Forecast Discussion
National Weather Service Pueblo CO
312 PM MDT Sat May 19 2018
.SHORT TERM...(This evening through Sunday)
Issued at 247 PM MDT Sat May 19 2018
Upper low will continue to lift off to the northeast with trailing
wave firing off showers/thunderstorms across the mountains moving
across during the evening. Best instability resides along the
southeast mountains and across the far southern plains bordering New
Mexico. MLCape showing up to 1000 j/kg down that with shears
running around 35-40 kts. Las Animas and Baca counties are
outlooked for marginal severe...though the slight risk area hugs the
border just to the south. This area will be the primary area to
watch for the potential for large hail and damaging winds later this
afternoon through this evening. Across the remainder of the plains,
nice cap in place with cool stable surface airmass, particularly
across northern portions of the plains. Dew points are actually
drying out a bit as well. So, though latest HRRR runs continue to
spread convection eastward onto the plains, suspect it will weaken
as it hits the cooler more stable airmass to the east. Best chance
for marginally severe hail will be across the eastern slopes of the
southeast mountains. Could also be looking at a localized flash
flood threat for burn scars like Junkins or Hayden should a stronger
storm impact these areas.
Convection should decrease pretty quickly this evening as lower
levels stabilize. Another round of stratus will develop across the
plains tonight, especially toward early morning for the Pikes Peak
region as low level winds shift around from the southeast.
For Sunday, another round of afternoon showers and thunderstorms can
be expected as another shortwave embedded in southwest flow aloft
moves across the area. Still looking at around 500 to a little less
than 1000 j/kg of CAPE across the southeast mountains during the
afternoon, with deep layer shears looking a little weaker, on the
order of 25-35 kts. Main focus for thunderstorms will be across the
central mountains according to NAM and GFS. Plains will stay largely
capped, but could see a storm or two drift off into the adjacent I-
25 corridor during the late afternoon/early evening. Main concern
with thunderstorms will be small hail and the potential for locally
heavy rainfall on the more susceptible burn scars. -KT
.LONG TERM...(Sunday night through Saturday)
Issued at 247 PM MDT Sat May 19 2018
...May Showers and Thunderstorms will Continue...
The weather pattern will continue to support more typical May
weather for the next several days. Southern Colorado will remain
under a moist and unstable pattern through Tuesday with daily rounds
of afternoon and evening showers and thunderstorms. Models keep the
region under moist, southwest flow with embedded disturbances
helping to trigger convection. One such disturbance will track
across the region Sunday afternoon, coincidental with peak heating,
to produce another round of showers and storms lasting into the
evening. As typical, convection will tend to initiate over the
mountains first and then work east across the plains. It does look
like the convection should hold together pretty well as it comes
across the I-25 corridor, so should be another round of showers and
embedded thunderstorms for most along the corridor. Right now, it
looks like convection will favor the northern half of the
corridor, including the Canon City, Pueblo and Colorado Springs
areas. Primary storm hazards will be lightning, small hail, 40 mph
winds and locally heavy rain.
Another disturbance will try to make it up into the area Monday
afternoon and evening. it currently looks like this will favor more
southern areas as the bulk of the disturbance remains over New
Mexico. However, with the moisture that remains, it should be
enough for another round of showers and storms. This time
convection will favor more southern parts of the region, including
the southern mountains and southern I-25 corridor. The primary
storm hazards will be similar to those on Sunday.
A third disturbance will track from southwest to northeast across
the area Tuesday afternoon and evening, bringing more showers and
storms. This looks like the last disturbance before a break in the
action occurs Wednesday into Thursday. During this time, a period
of warmer, drier westerly flow will set up across the region,
limiting precipitation chances and elevating the fire danger. It is
unclear at this time how high the fire danger will go. Will the
recent showers combined with more showers over the next few days
moisten and green things up enough to keep the fire danger down?
We`ll have to wait and see.
Then, after a brief dry spell, things trend wetter and more
unsettled again, possibly as early as Thursday evening over northern
parts of the forecast area but more likely Friday and Saturday over
the entire area. If recent model trends continue, Saturday will be
the wettest day with the best precipitation chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 247 PM MDT Sat May 19 2018
Isolated to scattered thunderstorms will continue over the mountains
and southern border areas of the southeast plains through this
evening with MVFR Cigs/vis. Thunderstorms should decrease in
strength as they drift eastward into cooler more stable conditions
across the plains. Strongest storm potential will be across the
border counties of Las Animas and Baca counties. Most thunderstorms
will diminish by this evening with MVFR cigs redeveloping across the
I-25 corridor affecting the KCOS and KPUB terminals overnight.
Southwest winds at KALS will remain gusty through 00z before
shifting from the east during the evening. Low level moisture will
increase tonight which elevates concerns for fog development towards
morning however model soundings and guidance do not support this.
Will not include fog in the TAF for now as it looks like a very low
probability occurrence. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...LW
AVIATION...KT
Area Forecast Discussion
National Weather Service Shreveport LA
945 PM CDT Sat May 19 2018
.UPDATE...
Only minor changes were made to the ongoing forecast. Isolated
showers continued to intermittently develop just east of La Salle
and Caldwell Parishes tonight, and thus have elected to maintain a
slight chance of showers mention through midnight. Scattered
strong to severe storms across west TX tonight is very slowly
shifting eastward with time, and computer models show
thunderstorm activity possibly affecting east TX by tomorrow
afternoon. However no severe weather is expected at this time.
Furthermore, tweaked the surface temperature curve to reflect
current trends, and subsequently tweaked the dewpoint temperatures
and relative humidity values.
&&
.PREV DISCUSSION... /issued 621 PM CDT Sat May 19 2018/
AVIATION...
VFR conditions will prevail through this evening. FEW-SCT VFR CIGS
will become FEW-SKC later this evening, whilst south-southwest winds
drop to below 10 kts shortly after sunset. Another round of MVFR to
possibly IFR CIGS are expected once again overnight, at all but
kmlu, ktxk and keld. However, would not be surprised if kmlu could
see some light patchy fog or haze overnight. Otherwise, any
lingering fog and low clouds will diminish by mid-late Sunday
morning, with SCT-BKN VFR CIGS becoming more prevalent by the
afternoon. Computer models hint at isolated to scattered
-SHRA/-TSRA that could affect just about any terminal Sunday
afternoon. Confidence is high enough for a VCTS mention at the
western terminals at this time, but will of course amend as
necessary. Otherwise, southerly wind speeds below 10 kts will ensue
Sunday.
PREV DISCUSSION... /issued 347 PM CDT Sat May 19 2018/
SHORT TERM...
Afternoon temps have climbed back to near 90 or the lower 90s
areawide this afternoon, despite the southerly winds that have
returned to the region. RH`s have increased as well, with heat
indices having already reached the mid 90s as of 20Z. Dry
conditions will continue through the evening and overnight hours,
as upper level ridging in place from E TX across the Lower MS
Valley will only drift slowly E of the region. Already seeing
quite a bit of convection that has developed atop this ridge (and
SSE of a broad shortwave trough over NE CO into NE) from NW TX
across Nrn OK/SE KS into Srn MO and the Mid-South region, much
like a ring of fire that occasionally occurs later during the
summer months. The sct cu field in place across the region this
afternoon will diminish around/shortly after sunset this evening,
although areas of AC/cirrus will linger over portions of NE TX/SE
OK/SW AR tonight, near and old weakening shortwave trough and
along the base of the aforementioned broad shortwave trough over
the Cntrl Plains which will drift NE overnight. The tail end of
this trough over the Srn Plains will allow for an increase in the
cirrus shield late associated with the ongoing convection over NW
TX/Wrn OK.
The latest HREF and HRRR solutions, as well as the 12Z
NAM/GFS/ECMWF suggest that this convection will remain well W of
the region late tonight, although associated outflow bndrys may
surge E beneath the Wrn periphery of the departing upper ridge.
However, have kept a dry forecast tonight given the lack of mean
lyr moisture, with H850 RH`s ranging between 25-30%. However, will
have to contend with the stratus shield returning to E TX/Wrn LA
late tonight, which should spread N across the remainder of NE
TX/NW LA and possibly portions of SW AR around/shortly after 12Z
Sunday, before scattering out by mid to late morning. H850
moisture begins to deepen by midday through Sunday afternoon in
advance the the Srn tail of the upper trough, and thus have
trimmed back pops Sunday morning to these areas, although strong
insolation/resultant instability should yield isolated convection
over portions if not much of the region by afternoon. Did retain
mention of slight chance pops Sunday evening for any lingering
isolated convection, but am expecting this to diminish for the
overnight hours as the bndry lyr stabilizes. The deeper low level
moisture in place should also yield max temps Sunday about 1-3
degrees cooler than what was observed this afternoon, but still
several degrees above normal as they climb into the upper 80s/near
90.
15
LONG TERM...
Deep upper low begins to form over sw usa durg beginning of work
week. At the same time, a weak upper low will enhance e-se flow into
the area with weak disorganized flow in the upper lvls. Moisture
will be added to the atmosphere with these two factors at work, and
the summerlike lack of steering will complicate the movement of any
boundaries that may interact with this increasingly moist and
unstable environment. Isold to scattered mainly aftn and early eve
convection more persistent to the east and possibly northern section
of area, due to its positioning with respect to the low in the gulf.
Once the closed low over the sw usa opens up and kicks out to the
ne, increasing northerly flow aloft will push remnants of a frontal
boundary swd into the area, with early wknd perhaps indicating best
coverage of convection this week. In the meantime, temps to remain
fairly persistent, mainly lower 90s in the daytime, and either side
of 70 degrees overnight, with variations mainly a result of
localized convective clusters that may develop. /07/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 71 91 71 91 / 0 20 20 30
MLU 71 90 70 90 / 10 20 20 40
DEQ 68 88 67 89 / 10 20 20 30
TXK 71 90 68 89 / 10 20 20 30
ELD 70 90 68 89 / 0 20 20 40
TYR 70 89 70 89 / 10 20 20 20
GGG 71 89 70 90 / 0 20 20 30
LFK 71 91 69 90 / 0 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
29/15/07