Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/12/17
Area Forecast Discussion
National Weather Service Albany NY
953 PM EDT Fri Aug 11 2017
.SYNOPSIS...
A warm front and an upper level disturbance will bring some showers
and thunderstorms to the region tonight. A cold front will slowly
approach the region from the west tomorrow with more showers and
potentially strong thunderstorms in a humid air mass. The cold
front will move east of the region Saturday night with a slightly
cooler, but a drier air mass building in for late in the
weekend into Monday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Updated forecast to track area of precipitation moving through
the CWA. Have used radar data and HRRR to get a handle on
movement of showers. As noted in the afternoon package, this
activity is supported by 250 hPa jet streak of 75-85 kts with a
good plume of upper level divergence. A few cloud to cloud
strikes noted a little earlier this evening in Ulster County.
00Z ALY sounding shows about 500 j/kg of most unstable CAPE
available. So still allowing for a slight chance of TSRA with
activity through the night. Sounding PWAT was 1.44 inches which
is about one standard deviation above normal. For the most part
rainfall rates across Ulster County have been around 0.25 inch.
However, the New York State Mesonet site at Claryville did show
about 1.20 inches between 830-930pm. So, generally around 0.25
inch, but up to one inch per hour possible in convective
elements.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Tomorrow...A lull in the showers/t-storms is possible in the
mid to late morning with the warm front slowly moving through
the forecast area. Eastern NY and western New England may get
into a mini-warm sector by the early afternoon. Attention
shifts to the approaching cold front from southeast Ontario and
the eastern Great Lakes Region. There will be a lot of cloud
cover around in the morning with some spotty light showers. The
12Z NAM and GFS are hinting at some breaks in the cloud cover
with some heating. If this heating occurs, surface-based
instability values of 1000-2000 J/kg may be realized by the
afternoon, if sfc dewpts in the lower to upper 60s occur. Both
the NAM/GFS are showing some steepening of the mid level lapse
rates by the mid to late pm in the 6.5C-7C/km /700-500 hPa
layer/ and the deep layer 0-6 km bulk shear increases to 30-40+
kts. Some discrete organized convection is possible if the
destabilization occurs. There is decent west to southwest flow
in the mid-levels, so multicells orienting into a line or two
may be possible. It looks like the initial storms could fire
with a pre-frontal trough. The SPC Day 2 has the entire area in
a Marginal Risk for severe thunderstorms. We added enhanced
wording for gusty winds and small hail to the gridded forecasts.
Some heavy rainfall is also possible, though a little drying in
the wake of the warm front and the short- wave tonight may
lower PWATS back to 1-1.5" for Saturday. The risk for some
strong to potentially severe thunderstorms looks greatest
between 18Z to 01Z/SUN. Any severe convection would be from
bowing segments yielding damaging winds, and large hail.
Highs on Saturday will generally be in the mid 70s to around
80F over the hills and in the valley locations with mid 60s to
lower 70s over the mountains.
Saturday night...The showers and thunderstorms will diminish
early on as the cold front pushes through the region. The
showers may hang on the longest across the southern Adirondacks
and the western Mohawk Valley due to the differential cyclonic
vorticity advection with the upper trough. Weak cold advection
occurs in its wake. Some patchy fog is possible across the
region with lows falling back into the mid 50s to lower 60s
across the region
Sunday...The upper level trough axis needs to move through in
the morning. Some isolated to scattered showers are possible
from the Capital Region north and west, then better mixing and
subsidence will occur in the wake of the trough passage. It
will be a breezy and less humid to close the weekend with highs
in the mid 60s to mid 70s over the hills and mountains, and mid
70s to lower 80s in the valley areas. Some downsloping with
west to northwest winds of 10 to 20 mph will allow portions of
the Capital Region and the mid Hudson Valley to still reach the
lower 80s.
Sunday night...Diminishing winds and mostly clear/clear
conditions are expected with high pressure ridging in from the
Great Lakes Region. Humidity levels will be comfortable, and
lows will be in the 50s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
In the mean, a broad upper level trough will be in place across the
eastern U.S. during the period.
Meanwhile at the surface, high pressure will be the dominate feature
for most days.
For now, the best chance of rain looks like it will be on Tuesday as
a weak shortwave trough approaches and transits the region. Even
though Tuesday is the best chance for rain, POPS are only slight
chance to chance across the area.
Otherwise, Monday, Wednesday, and Thursday look dry with increasing
sunshine Wednesday and Thursday.
Temperatures and humidity levels will be fairly typical for mid
August with highs in the low 80s valleys to 60s and 70s higher
elevations. Dew points will generally be in the 50s.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
With no observation since 17Z, AMD NOT SKED introduced at KGFL.
Area of RA moving into southern forecast area now. Activity has
skirted KPOU. In general looking for MVFR condition to develop
this evening at all terminals in RA. It is possible that a
terminal could experience a TSRA tonight, but not capable of
picking the terminal nor the time, so no mention in TAFs.
With lower CIGS and VSBYS expect all terminals to experience IFR
conditions in the 06-12Z period.
For Saturday, area is in marginal risk for severe
thunderstorms. At this time, will not introduce TSRA given lack
of confidence in specifying time and location. I have covered
with VCSH for Saturday afternoon. In time, this will get more
specific.
Outlook...
Saturday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday: Low Operational Impact. Isolated SHRA.
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: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A warm front and an upper level disturbance will bring some showers
and thunderstorms to the region tonight. A cold front will slowly
approach the region from the west tomorrow with more showers and
potentially strong thunderstorms in a humid air mass. The cold
front will move east of the region Saturday night with a slightly
cooler, but a drier air mass building in for late in the
weekend into Monday.
The RH values will increase to 85 to 100 percent tonight and
Saturday night. The RH values will only fall to 50 to 65
percent Saturday afternoon.
The winds will be south to southeast at 5 to 10 mph tonight and
south to southwest at 5 to 15 mph tomorrow. The winds shift to
the west to northwest at 5 to 15 mph Saturday night into Sunday
with the cold frontal passage. Some gusts in the 20 to 30 mph
range are possible on Sunday.
Showers are likely tonight with isolated to scattered
thunderstorms. More showers and thunderstorms are possible
Saturday into early Saturday night with the cold front.
&&
.HYDROLOGY...
No widespread problems are expected on the main stem rivers the
next several days.
Showers and thunderstorms will develop tonight through
Saturday night, as the next low pressure system approaches from
the Great Lakes region with its associated warm and cold
fronts. Because of the scattered nature of the convection
tonight through Saturday, basin wide rainfall amounts are
expected to be three quarters of an inch or less but localized
amounts of an inch or more are possible in thunderstorms with
local ponding of water on roadways or poor drainages flooding of
low lying areas.
The showers and thunderstorms will diminish Saturday night with
the cold frontal passage. Only additional light rainfall
amounts are possible on Sunday for locations north and west of
the Capital Region with a few hundredths to a tenth of an inch
with the upper level trough.
Drier weather returns Sunday afternoon through Monday with high
pressure building in.
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...OKeefe/Wasula
SHORT TERM...Wasula
LONG TERM...OKeefe
AVIATION...OKeefe
FIRE WEATHER...NAS/Wasula
HYDROLOGY...NAS/Wasula
Area Forecast Discussion
National Weather Service Birmingham AL
648 PM CDT Fri Aug 11 2017
.UPDATE...
Aviation Discussion.
&&
.SHORT TERM...
This Afternoon and Tonight.
Widespread cloud cover and cooler temperatures this afternoon
produced a more stable air mass across central Alabama, limiting
areal coverage and intensity of convection. More sunshine across
the far southern counties has produced more thunderstorm activity,
but the stronger storms have been south and west of Montgomery
and Troy. Radar shows a line of stronger storms west of Troy and
there may still be a limited threat for heavy rainfall with this
activity as it tracks eastward, and possibly sends an outflow
boundary northward towards Montgomery. The flash flood watch has
been reduced to areas along and south of I-85 and the expiration
time is now 7 pm instead of midnight.
Minimal shower and thunderstorm activity expected across central
Alabama after 9 pm. The lone exception may be the northwest
counties as a cluster of storms over northern Mississippi tracks
southeast. Latest HRRR model shows this activity holding together
a little longer, so rain chances may need to be raised in future
updates. Low clouds and fog likely to develop late tonight.
58/rose
.LONG TERM...
Saturday through Thursday.
As we work into the weekend, the big question will be can the next
front push through or does it stall out once again across the area.
Most of the models now are keeping the front either across our
northern counties and then sliding it north by Sunday, or keeping it
north of the area the entire time. The Canadian model is now the
only model that still pushes the front through. So will once again
trend toward the wetter pattern for the extended as there really is
nothing that will push it out of the Southeast. So on a whole look
for still above normal precipitation with near normal temperatures
for the period.
16
&&
.AVIATION...
00Z TAF Discussion.
Isolated showers are beginning to diminish this evening. There is a
decaying line of storms moving into Central Alabama from MS, that
could leave a boundary and provide a focus for isolated showers this
evening. Will leave VCSH in the forecast for northern terminals
through 05-06Z. Low clouds and fog are expected overnight, with IFR
conditions by sunrise. Will need to watch for localized LIFR
conditions. Cigs/Vis will slowly improve through the morning hours,
with broken MVFR cigs through the day. By mid day, expect showers
and TS to develop across the north, with activity near MGM and TOI
by mid afternoon.
Winds will be light/variable or calm overnight, increasing to 5-6kts
from the southwest to west Saturday.
14
&&
.FIRE WEATHER...
Above normal rain chances are expected through the weekend and
into next week. There are no fire weather concerns.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 72 88 71 88 72 / 30 40 30 50 30
Anniston 72 87 72 89 73 / 30 60 30 60 30
Birmingham 74 89 73 90 74 / 30 40 30 50 30
Tuscaloosa 74 91 73 91 74 / 30 50 30 50 30
Calera 73 89 73 90 74 / 30 50 30 60 30
Auburn 73 88 74 89 74 / 30 60 30 60 30
Montgomery 75 91 75 92 75 / 30 60 30 60 30
Troy 73 90 74 91 74 / 30 60 30 60 30
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
Flash Flood Watch until 7 PM CDT this evening for the following
counties: Barbour...Bullock...Lowndes...Macon...Montgomery...
Pike...Russell.
&&
$$
Area Forecast Discussion
National Weather Service Taunton MA
1023 PM EDT Fri Aug 11 2017
.SYNOPSIS...
Low pressure from the Great Lakes moves E/NE tonight and Saturday.
This will draw a warm front up across S New England by Saturday
morning, then swing a cold front through Saturday night. With
the remainder of the weekend dry, some shower chances emerge
through the week, mainly Tuesday, but nothing of a wash out.
Overall seasonable conditions with low humidity. However, long-
range, may see warmer summertime conditions return.
&&
.NEAR TERM /THROUGH SATURDAY/...
Made further changes to the forecast this evening. Primary
changes were to rainfall timing, which looks to be well handled
by the majority of the near-term guidance. expecting mostly
showers across the western half of southern New England through
about 2 AM, then overspreading the rest of our region
thereafter.
Minor tweaks to temperatures to reflect observed trends.
Previous Discussion...
Turning wet around midnight. Fair amount of theta-E moisture
associated with a mid-level vortmax pivoting round the broader
troughing regime across the region. Precipitable waters rising
especially along the S-coast with values up to 2-inches, some
early indications simply given the more soupy airmass pushing
into the region with lower clouds and reduced visibility.
Have made some modifications to the forecast. A marginal setup
given a strong influx via SW flow of higher theta-E within a
conditionally unstable airmass. Mainly focused on the rain which
has the potential of being heavy, the greater risk of which is
along the S-coast in lock step with a H925-85 theta-E gradient
along which low-level winds are to a degree convergently focused
(though the stronger convergence, if the RAP is correct, remains
mainly over the waters). The possibility of a rumble of thunder,
mainly leaning higher categorical of rain with lesser threat of
thunder. Prevailed with "heavy rain" wording in the forecast.
The S offshore Islands at greatest risk, especially Nantucket,
of heavy rain. The over-running setup, went with LIKELY to
DEFINITE PoPs.
A word of caution. A lot of energy and subsequent area of low
pressure streaming into the interior NE CONUS parent with the
mid to upper level low out of the Great Lakes Region. Though the
lower heights are also pulling N the sub-tropical warm front just
S/E offshore. Two neighboring areas of low pressure, as we`ve
seen before in this situation before someone is going to see
very little if anything subsequent of a subsidence wedge. Looking
at a region SW to NE across S New England. Places such as Boston
up the NH/ME coastline may only see wet-weather associated with
the main vortmax sweeping through around midnight into the early
morning hours on Saturday then very little after that. Something
to monitor as we go through the next 24 hours.
Mild night, soupy along the S-shoreline with a greater propensity
of low clouds and fog. Lows in the 60s.
&&
.SHORT TERM /SATURDAY NIGHT/...
Saturday morning...
The first shortwave moves past New England during the morning.
This may be enough to move the warm front through our area and
bring us a more humid airmass. Expect showers to continue during
the morning, and then most will taper off as the warm front
moves past.
Saturday afternoon and night...
The second shortwave approaches from the Midwest Saturday
evening and crosses New England toward Sunday morning. The cold
front associated with this shortwave will cross NY and PA during
the afternoon and then cross New England Saturday night.
Difficult to determine the presence of a pre-frontal surface
trough ahead of the front, one that could be a focus for
convection to fire. Model theta-e fields do show a theta-e ridge
crossing the Northeast Corridor Saturday afternoon/evening.
After a short break early Saturday afternoon, expect a second
round of showers mid to late afternoon. Totals are forecast at
47-51 after 18Z, with lifted index sub-zero. So along with the
showers, we should also have a few thunderstorms. Winds aloft
are rather light for generating any damaging gusts, although 500
mb winds do increase to 50 knots around midnight. This is a
little late for us regarding any severe weather. So at this time
we are not thinking of any severe storms in our area.
Total rainfall amounts through Saturday night should generally
range between one-half and one inch, with the greatest amounts
toward the south coast, including the Cape and islands.
Once the cold front moves through, expect winds to shift out of
the west and showers/storms will move off.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
*/ Highlights...
- Overall dry pattern, some shower chances, but nothing drenching
- Seasonable conditions with low humidity overall
- Long-range pattern change, could see warmer temperatures return
*/ Overview...
A downstream cascade of outcomes. Within the mid- to upper-levels,
progressive deep troughing over N-Central Asia acts to cut off an
area of low pressure near the Kamchatka Peninsula. Both continuing E
subsequently flip the dipole over the N Pacific with lower pressure
building into the Aleutians and high pressure developing over the
Gulf of Alaska. The subsequent breakdown seemingly has implications
downstream with flow becoming more zonal across the CONUS with less
amplification of preferred troughing over our region. Subsequently
there are indications of a slight warm-up across the region at times
interrupted by continued weak Pacific-origin impulses and chances of
wet-weather. Overall though it would appear that the sub-tropical
airmass and more sultry air is buffered offshore, thus conditions do
look to remain comfortable. Will hit on specifics below.
*/ Details...
Sunday into Monday...
Lingering showers early Sunday, turning dry. Sunday morning cool
frontal push along with a mid-level trough axis, much drier air
builds into the region. Increasing confluence of mid to upper level
flow aloft, surface high pressure builds across the region Monday,
light winds contributing to onshore sea-breezes. Scattered to broken
cloud decks associated with some mid-level energy through the
confluent flow. Overall a dry period of weather with near-seasonable
temperatures and low humidity.
Tuesday into Wednesday...
Possibly our next best chance of wet-weather. Confluent mid to upper
level flow becoming lax, deeper troughing and attendant vortmax
energy sweeping the region. Model forecast guidance mixed as to
whether the offshore sub-tropical quasi-stationary boundary lifts
back to the N or rather shower / thunderstorm activity developing
over the N/W interior of the NE CONUS impacts our region. Could be a
situation where S New England is wedged-out within subsidence being
neighbored by two areas of lower pressure. Will keep the mention of
chance PoPs on Tuesday given better moisture availability, also lean
warmest conditions for the week. Wednesday looks to remain dry with
the majority of forcing/lifting mechanisms swept through the region
behind which cooler, drier air builds in.
Thursday into Friday...
Dry, near-seasonable, slight warm-up by day. High pressure building
across the region yet again. Cooler airmass in place on Thursday
which is quickly replaced Friday by warmer, S flow. Both days the
winds have the potential of being light to allow onshore sea-breeze
winds. Increasing clouds late on Friday with the chance of showers
overnight ahead of a warm-frontal boundary.
Weekend...
Potentially wet on Saturday, dry Sunday. A warm front looks to lift
through the region, hanging along the coast up against the cooler
waters. S flow increasing as the mid to upper level pattern exhibits
less troughing, looking at a possible slow build up of heat and
humidity with the chances of showers and thunderstorms into early
next week. Way out there, very early to say, so a low confidence
forecast. But if the mid to upper level pattern is changing as was
addressed in the overview, the pattern we`ve seen as of late of
continued N flow of cooler and drier air may become relaxed allowing
warmer Summer conditions to return as hinted by the Climate
Prediction Center`s 6-10/8-14 day outlooks.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday Night/...
Tonight...Moderate confidence.
VFR lowering towards MVFR into morning for most terminals. South
coastal terminals in a IFR-LIFR soup already. Light S winds.
Light RA spreading SW to NE overnight, could be RA/+RA along
the south coast by morning.
Saturday...Moderate confidence.
MVFR lifting back to VFR across the interior, but the IFR-LIFR soup
continues to plague S-coastal terminals. ACK at the highest risk
of remaining in low clouds all day. Increasing S winds. -RA and
possible TSRA encroaching from the S/W late, potentially impacting
the W terminals, sliding along the S-coast into evening. From
roughly BDL-ORH and terminals N/E up through BOS may have no
issues at all.
Saturday night...
VFR lowering back down to MVFR briefly across the interior before
winds shift back out of the W. IFR-LIFR continues to plague S-coastal
terminals, clearing out towards Sunday morning with the wind shift.
KBOS Terminal...
Will keep with VFR lowering to MVFR shortly after midnight with -RA.
Feel the terminal may not experience much in the way of issues
through the TAF period over the next 30 hours.
KBDL Terminal...
VFR lowering to MVFR with likely rain around midnight. There is
the possibility of RA/+RA though feel the better risk will hold
to the S of the terminal overnight. Though no mention, there is
a risk of TSRA late Saturday from the W/SW.
Outlook /Sunday through Wednesday/...Moderate confidence.
Sunday...VFR. Lingering SHRA across S/E coastal terminals,
otherwise dry. N/W winds breezy during the day, lax overnight.
Monday...VFR. Light winds. Sea-breezes possible. SCT-BKN mid-
high CIGs.
Tuesday...
VFR. S winds, breezy. Possible SHRA/TSRA, better chances N/W.
Wednesday...VFR. Winds shifting N/W, initially breezy,
becoming light. Sea- breezes possible.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday Night/...High confidence.
A Small Craft advisory may be needed on the southern outer
waters Saturday night.
Southerly winds tonight and Saturday shift from the west later
Saturday night as a cold front moves across the waters. Winds
remain less than 20 knots through Saturday night. The sustained
south flow prior to that may build 5 foot seas on the southern
outer water by Saturday night.
Showers and areas of fog will bring reduced visibility through
much of Saturday night.
Outlook /Sunday through Wednesday/...Moderate confidence.
Showers clearing out over the waters early Sunday making for a nice
weather the remainder of the day, though breezy out of the N/W. For
the small boaters especially, can`t rule out gusts up to 20 kts.
Will see winds diminish into Monday with high pressure. Monitoring
for possible encroaching rain from the S on Tuesday with perhaps
some breezy SW flow, otherwise Wednesday looks to be good boating
weather with N/W winds behind a Tuesday night cool frontal
passage.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...WTB/Sipprell
NEAR TERM...WTB/Belk/Sipprell
SHORT TERM...WTB
LONG TERM...Sipprell
AVIATION...WTB/Sipprell
MARINE...WTB/Sipprell
Area Forecast Discussion
National Weather Service Cheyenne WY
510 PM MDT Fri Aug 11 2017
.SHORT TERM...(This evening through Sunday night)
Issued at 120 PM MDT Fri Aug 11 2017
Forecast challenges with this package deals with severe thunderstorm
potential both today and Saturday.
Currently...Upper ridge remains stationary over the northern
Rockies from northern Idaho to northern Utah into southwestern
Colorado this afternoon. Water vapor imagery showing a small
disturbance moving through the ridge into south central Wyoming
this afternoon thats interacting with low level moisture and the
tail end of a stationary front on surface analysis. A stronger low
pressure system can be seen on water vapor imagery over north
central Montana that will have some impacts on us tomorrow. Latest
mesoanalysis showing surface based CAPE up to 1500 J/KG over
Converse and Niobrara Counties this afternoon at 1PM. Radar is
starting to light up on convection mainly in this area, extending
south into northern Platte County.
Latest HRRR simulated radar showing the area of convection over
Converse County dropping south as the afternoon progresses and
this is what the SPC mesoanalysis page also shows with increasing
CAPE. We could see a few severe thunderstorms down here in Laramie
County late this afternoon just east of Cheyenne if the HRRR
forecast comes true. Forecast CAPE up to 1500 J/KG by 23Z across
Laramie County.
Better chances for severe thunderstorms Saturday as that Montana
low tracks southeast into western South Dakota. By late Saturday
afternoon, upper low near Rapid City with a cold front moving
south into Converse and Niobrara Counties. Afternoon MUCAPE from
NAM up to 2500 J/KG. Pretty high shear values as well with
northeast surface winds at 10kts and upper level winds at 65kts at
350mbs. Agree with SPCs Slight Risk area they have identified for
the Panhandle and would only maybe shift it a little further west
into Wyoming. Good shear means we will likely see a few severe
thunderstorms with very large hail. Did introduce severe
thunderstorms into the weather grids for the Panhandle and extreme
southeastern Wyoming for tomorrow afternoon/early evening. Also
updated HWO and weather story to reflect current thinking.
Sunday may be a little drier with upper ridge starting to move
into western WYoming. Most of the precip should be down over
Colorado Sunday, but we could see a few thunderstorms coming off
the mountains Sunday afternoon, so kept low chance PoPs going.
.LONG TERM...(Monday through Friday)
Issued at 120 PM MDT Fri Aug 11 2017
Monday...Expect to see a decrease in afternoon and evening shower
and thunderstorm coverage as a ridge aloft moves overhead. Still
though, enough low and mid level moisture for isolated to widely
scattered afternoon and evening showers and thunderstorms. Definite
warming trend with more sunshine and a moderating airmass.
Tuesday...With a shortwave trough aloft moving overhead in the
afternoon, and adequate low and mid level moisture, expect to see
scattered showers and thunderstorms develop, especially east of
Interstate 25.
Wednesday...In the wake of the shortwave trough aloft, will see some
low and mid level drying, thus minimal chances for showers and
thunderstorms in the afternoon and evening. Warming trend continues
with more sunshine and downslope winds.
Thursday...Continued mild per thicknesses and mid level
temperatures. Flow aloft becomes northwest and with limited low and
mid level moisture, minimal chances for showers and thunderstorms.
Friday...Continued dry and seasonably mild with the flow aloft
backing to zonal, west to east, and limited low and mid level
moisture to fuel any showers or thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 510 PM MDT Fri Aug 11 2017
Wyoming TAFS...VFR prevails, with thunderstorms near terminals until
02Z producing wind gusts to 35 knots and again after 20Z on
Saturday. Although low stratus and fog are possible at KCYS,
confidence is pretty low at this time.
Nebraska TAFS...VFR prevails, with thunderstorms until 04Z producing
wind gusts to 45 knots. Low CIGS are possible by early Saturday
morning, but confidence is rather low at this time.
&&
.FIRE WEATHER...
Issued at 120 PM MDT Fri Aug 11 2017
Minimal fire weather concerns as a cool and unsettled weather
remains in place across southeast Wyoming and Nebraska Panhandle.
Upper ridge over the northern Rockies will keep a northwest flow
over the area with disturbances moving across our area from the
northwest on a daily basis. Rainshowers and thunderstorms look to
occur on a daily basis with these disturbances, so most areas
should see measurable rainfall at least Tuesday before drying out
towards the end of next week.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RUBIN/TT
FIRE WEATHER...GCC
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
641 PM CDT Fri Aug 11 2017
.AVIATION.../00Z TAF CYCLE/
VFR conditions prevail are and expected through the the 24-30 hour
period. While the NAM continues to be more aggressive with low-level
moisture Saturday morning, both the GFS and recent time-series of
the HRRR suggest lower saturation levels. Have continued the SCT010
grouping for KAUS/KSAT/KSSF sites given the low probability of MVFR
ceilings. Some very patchy MVFR/IFR ceilings could occur west across
the higher terrain of the Escarpment region but actual TAF sites
should remain VFR. will need to monitor HRRR trends overnight to see
if KSAT/KSSF could briefly go MVFR in the 11-15Z time-frame. OVerall
confidence is low at this time. Surface winds will be south to
southeast at 5-10 knots overnight with some periodic gusts to near
15-20 knots near KDRT by Saturday afternoon.
&&
.PREV DISCUSSION... /ISSUED 153 PM CDT Fri Aug 11 2017/
SHORT TERM (Tonight through Saturday Night)...
The mid and upper level ridge will continue to stretch from west to
east across the southern U.S. through the weekend. The ridge axis is
just about right over south central Texas, so we expect little change
in conditions from today through Sunday. A little drier air will work
into the northern portions of the area for Saturday and Sunday, so
the Heat Advisory area will be scaled back to counties east of
Interstate 35 for those two afternoons.
LONG TERM (Sunday through Friday)...
The ridge begins to break down and thin out, with easterly flow
becoming established across the northern Gulf by midweek. This
onshore flow will increase PW and allow easterly waves to enter the
state. With typical summertime instability already in place, the
ingredients will then be present for isolated to scattered showers
and thunderstorms. The best chances will be Tuesday and Wednesday
across the coastal plains, but many locations in south central Texas
will remain hot and dry through the end of next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 76 100 76 100 77 / - 0 0 0 0
Austin Bergstrom Intl Airport 75 99 75 100 76 / - 0 0 0 0
New Braunfels Muni Airport 75 99 74 100 75 / 0 0 0 0 0
Burnet Muni Airport 74 97 74 98 74 / 0 0 0 0 0
Del Rio Intl Airport 78 101 78 103 78 / 0 0 0 0 0
Georgetown Muni Airport 76 98 75 98 76 / 0 0 0 0 0
Hondo Muni Airport 75 100 75 102 76 / 0 0 0 0 0
San Marcos Muni Airport 75 99 75 100 76 / - 0 0 0 0
La Grange - Fayette Regional 77 99 76 99 77 / 0 0 0 - 0
San Antonio Intl Airport 76 99 76 101 77 / 0 0 0 0 0
Stinson Muni Airport 76 99 76 101 77 / 0 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT this evening for the following
counties: Atascosa...Bastrop...Bexar...Caldwell...Comal...De Witt...
Fayette...Gonzales...Guadalupe...Hays...Karnes...Lavaca...Lee...
Travis...Williamson...Wilson.
Heat Advisory from 2 PM to 7 PM CDT Saturday for the following
counties: Atascosa...Bastrop...Caldwell...De Witt...Fayette...
Gonzales...Guadalupe...Karnes...Lavaca...Lee...Wilson.
&&
$$
Mesoscale/Aviation...Allen
Synoptic/Grids...Oaks
Public Service/Data Collection...30
Area Forecast Discussion
National Weather Service Green Bay WI
1046 PM CDT Fri Aug 11 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Saturday
Issued at 210 PM CDT Fri Aug 11 2017
Cyclonic flow over the region were keeping clouds around along
with cooler afternoon temperatures. Various models including the
short range runs continue to develop isolated light showers
across the area during the remainder of the afternoon, but so far
only spots of drizzle or sprinkles were noted. Local radars show
light showers over the area, with more numerous showers with
isolated storms over Lower Michigan. The HRRR even produces a few
light showers over Door County late tonight, where the cyclonic
flow may linger a bit longer and some instability contribution
with the cooler air flowing over the Great Lakes region. Will
leave dry for now due to limited coverage of showers this
afternoon.
High pressure approaching from the west along with drier air on
northwest winds were gradually eroding the clouds or increasing
the base height over central and north central Wisconsin early
this afternoon. Appears this trend of clearing is lagging so will
slow down this trend this afternoon and evening across northeast
Wisconsin.
Eventually clearing skies and diminishing winds will prevail
across much of the area, and allow temperatures to fall.
Typical Climatological cool spots of central and north-central
Wisconsin may make a run toward the upper 30s to around 40.
High pressure settling over the area Saturday will allow abundant
sunshine and allow temperatures to return closer to normal.
.LONG TERM...Saturday Night Through Friday
Issued at 210 PM CDT Fri Aug 11 2017
A fairly stable pattern will be in place across North America over
the next week, consisting of a potent ridge slowly moving east over
central Canada. Will therefore see mainly quiet conditions until
this ridge passes to our east, which will allow the deep layer flow
to turn back to the southwest and increase precip chances. Plenty
of differences in the models by this time, and prefer a solution
closer to the gfs.
Saturday night through Monday...Conditions will start out quiet on
Saturday night with a large area of high pressure in control. Dry
conditions will probably continue into Sunday morning, but clouds
will be on the increase as weak shortwave energy moves into the
region. This shortwave will move across the region during Sunday
afternoon into Sunday night. Progged soundings indicate that the
atmosphere will struggle to saturate below 700mb, so cannot see much
more that scattered light showers and sprinkles during this time.
Clouds will then decrease behind the shortwave for late Sunday night
into Monday morning. Scattered high based cu is likely to form on
Monday, but precip chances look too low to mention at this time.
Comfortable temps near normal over this period.
Rest of the forecast...High pressure is then projected to stick
around for Tuesday into much of Wednesday. The flow will be
shifting more to the southwest aloft during this time, so think
precip chances will gradually ramp up late Wednesday into Thursday.
Temps and humidity levels will also be slowly increasing during this
time.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1046 PM CDT Fri Aug 11 2017
Clouds should exit northeast Wisconsin by around 12z
Saturday. Some MVFR ceilings are possible east of an Iron Mountain
to Green Bay line, but it will mostly be VFR. Good flying weather
is expected Saturday through Sunday except for areas of ground fog
Sunday morning between 09z and 12z.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TDH
LONG TERM......MPC
AVIATION.......RDM
Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
816 PM CDT Fri Aug 11 2017
.NEAR TERM...(Tonight)
Issued at 816 PM CDT Fri Aug 11 2017
Loosely organized MCS was moving southeast through southern TN and
north central AL. Radar trends indicate that the intensity of the
rainfall has diminished somewhat. We have had reports of 1.5-2.75
inches of rain in and around HSV in the past couple of hours, with
2.60 at UAH/MIPs adjacent to here at the NWS office. The HRRR trends
indicate a similar trend of further weakening/dissipating over the
next couple of hours as the system moves southeast. Have updated
PoP/Wx grids to account for this trend. Will leave a 20-30 PoP after
06Z given the very moist and unstable airmass we have in place.
Otherwise, low clouds will once again redevelop and plague the area
late tonight into Saturday morning.
.SHORT TERM...(Saturday through Sunday)
Issued at 230 PM CDT Fri Aug 11 2017
Overall the model chaos continues in the short term. The guidance all
agrees that a series of shortwaves/embedded vortices will round the
base of the longwave trough across the Mid Mississippi Valley and
across the Tennessee Valley sometime in the Saturday-Sunday time
frame. Unfortunately, in this type of pattern the timing is all over
the place. The 12z ECMWF swings a rather notable s/w across the area
on Sunday while the NAM/GFS are subsident on Sunday.
Conversely the GFS/NAM have a much stronger shortwave on Saturday
while that feature is not as well depicted in the ECMWF. For now,
will have slightly higher pops overall for Saturday (where PWATs will
be similar to the past 24 hours) but generally mid range both days.
Given high PWATs and saturated soils, the largest concern will
continue to be heavy rainfall/flash flooding. Temperatures will
also continue to run 5-7 degrees below normal through the weekend.
.LONG TERM...(Sunday night through Thursday)
Issued at 230 PM CDT Fri Aug 11 2017
The extended seems like a rinse and repeat with unsettled weather
lingering through the week and nearly steady temps. An upper-level
trough will dig out of the Northern Plains on Monday and as a sfc low
lifts through the OH Valley, a front will stall near the TN Valley.
Heavy rainfall and gusty winds will be the main threats with these
storms as once again, moisture will not be a problem with PWATS ~2
inches and a lack of shear. Rain chances will decrease as we head
into the middle of the week as Great Lakes sfc high pressure builds a
little bit into the region. As for temps, look for daytime highs in
the mid/upper 80s with overnight lows around 70.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 558 PM CDT Fri Aug 11 2017
Clusters of thunderstorms and showers will occur this evening, mainly
before 03Z. Visibility may be reduced to 2sm or less in heavy
rainfall with ceilings at or below 025agl. Given the very moist
airmass, low clouds are again expected to develop late tonight into
Saturday morning. Ceilings of 010-015agl are likely, and could drop
to around 006agl in some areas. The ceilings should lift slowly
Saturday morning, with VFR conditions returning by around 18Z with
scattered cumulus of around 040agl.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...17
SHORT TERM...15
LONG TERM...JMS
AVIATION...17
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Wichita KS
608 PM CDT Fri Aug 11 2017
.SHORT TERM...(This evening through Monday night)
Issued at 245 PM CDT Fri Aug 11 2017
Cold front that pushed through KS late last night is currently
situated down along the Red River with a slightly cooler and drier
airmass spilling into the region. Water vapor imagery shows an
impulse embedded in the moonsonal flow over the desert sw and
lifting to the northeast.
Made some fairly significant changes to precip chances for
tonight and Sat to basically decrease chances. Best storm chances
tonight now look to remain southwest of the forecast area where
better 850-700mb moisture transport will be situated. Models also
in good agreement that shower/storm chances associated with the
moonsonal impulse, will be very slow to work back to the northeast
for Sat, keeping the bulk of the activity down in OK. So feel
that most of the area will remain dry Sat with the exception of
southwest portions of the forecast area. Will hold onto some storm
chances Sat night but confidence is much higher for locations
across far southern KS and especially OK.
For Sun there is good model agreement that shortwave energy will
be tracking across the northern Mississippi Valley and approaching
the western Great Lakes region. Meanwhile, the Plains will remain
in unseasonably strong west/nw flow with a series of weak
perturbations sliding through. Will maintain some small precip
chances for Sun into Sun night but confidence is very low at this
time and would not be surprised if precip chances are removed for
Sun with later forecasts.
The GFS is much more aggressive than the ECMWF, and somewhat the
NAM, in tracking upper energy out of the Rockies and across KS Mon
into Mon evening. Meanwhile, the ECMWF and NAM keep the bulk of
the precip south of the forecast area. Once again, will hold onto
storm chances Mon-Mon night with low confidence in this occurring.
Confidence is much higher with regards to temps as they will
remain well below seasonal averages as they top out in the 80s.
.LONG TERM...(Tuesday through Friday)
Issued at 245 PM CDT Fri Aug 11 2017
Pattern looks to remain unsettled through at least mid week
before upper ridging starts to strengthen over the southern Plains
which will push the stronger westerlies north. So at this time
feel the better precip chances will be through Wed night, before
we enter a less progressive pattern. Should also see a return to
more seasonal temps by the end of the work week as we get highs
back to the low 90s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 610 PM CDT Fri Aug 11 2017
High pressure ridging into the area will continue this evening.
Overnight, several of the latest runs of the HRRR have produced an
MCS moving into the region overnight. Arrival will be at GBD by
10z and areas east of there (HUT/ICT) by 12z. Introduced a VCTS
for GBD but will hold off until more confident for TAFs east of
there.
What happens with this convection will drive much of Saturday. Any
precipitation will be south of I-7o in eastern KS.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 66 80 66 82 / 10 20 30 20
Hutchinson 65 79 64 82 / 10 20 30 20
Newton 64 78 64 81 / 10 10 20 20
ElDorado 65 79 64 81 / 10 10 20 30
Winfield-KWLD 67 80 66 82 / 10 20 30 20
Russell 62 81 64 83 / 10 30 30 20
Great Bend 63 80 64 83 / 20 40 30 20
Salina 63 82 64 84 / 10 10 20 30
McPherson 64 80 63 82 / 10 20 20 30
Coffeyville 64 82 67 80 / 10 10 40 60
Chanute 63 81 65 80 / 10 10 20 40
Iola 63 81 65 80 / 10 10 20 40
Parsons-KPPF 63 82 67 80 / 10 10 30 50
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...RBL
LONG TERM...RBL
AVIATION...CWH
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1016 PM CDT Fri Aug 11 2017
.UPDATE...
A batch of scattered showers and t-storms have developed along a
confluent zone across the central and eastern South Plains in
conjunction with a larger-scale outflow boundary moving southwest
from the Rolling Plains onto the Caprock. This activity will
continue to move northeast over the next few hours, although we
can`t rule out some additional isolated development along the
outflow boundary.
Of greater concern is the t-storm activity in New Mexico
associated with a mid-level vortmax. The latest satellite and
radar imagery shows one MCS taking shape across northeast NM
leaning into the western Panhandles, with indications of another
developing in the vicinity of the Sacramento Mtns in south-
central NM. The latest high-res guidance including the HRRR and
TTU-WRF along with the 00 UTC NAM suggest that this activity will
progress across much of our forecast area in the early morning
hours Saturday - although there is quite a bit of difference in
the details. We have the highest confidence of storms affecting
our western and northern counties, but the picture becomes more
murky to the south and east as the LLJ will be weakening by the
time storms approach that area - likely leading to their weakening
as well. Some pockets of heavy rainfall are certainly possible
across the southwest Texas Panhandle and western South Plains.
PoPs have this scenario well represented and we`ve made only a few
minor adjustments.
&&
.PREV DISCUSSION... /issued 649 PM CDT Fri Aug 11 2017/
AVIATION...
Isolated convection has recently been attempting to develop
between KPVW and KCDS along a residual boundary, but this activity
will likely fade out later this evening without impacting either
terminal. Of greater concern is more widespread convection
currently over central New Mexico. There is a good signal that a
large batch of showers and thunderstorms will move eastward out of
New Mexico late tonight and across parts or much of the South
Plains region Saturday morning as it gradually decays. Given this
we have decided to include PROB30 remarks at all three terminals
valid Saturday morning at KLBB and KPVW (for thunder) and at KCDS
(for showers) from late morning into the early afternoon.
Increasing moisture may also support the development of sub-VFR
ceilings at times Saturday morning, while light winds prevail
outside of any thunderstorm influences.
PREV DISCUSSION... /issued 402 PM CDT Fri Aug 11 2017/
DISCUSSION...
The biggest change with this forecast iteration was to boost PoPs
considerably late tonight through Sat morning over much of the
Caprock. Rationale for this is tied to a well defined mid-level
vorticity maximum exiting southeast AZ. Water vapor imagery shows an
axis of deeper ascent ahead of this impulse - the leading edge of
which should reach our western zones after midnight. Until then, the
main focus for rain chances appears to favor the southern Panhandle
near a stationary front partially reinforced from overnight storms.
Visible satellite shows agitated Cu near Tulia just after 3 PM which
could easily manifest into some storms with max heating/convective
temps just around the corner. Continued light upslope winds should
also aid in low level ascent for at least spotty storms despite
prevalent upper ridging.
As the aforementioned impulse exits NM on Saturday, the upper ridge
will completely erode as 20-40 meters worth of mid-level height
falls unfold. Such forcing this time of year is sizable enough to
sustain the early A.M. precip through most/all of the morning.
Pending the behavior of the lingering frontal boundary, models favor
the brunt of precip to affect our N-NW zones. PWATs of 1.5 inches on
the Caprock would easily breed some heavy rainfall at times, but
sufficient W-SW flow aloft should keep precip progressive enough to
stave off a larger flooding threat. This more definitive round of
morning precip and thicker clouds could deal a blow to PoP chances
later in the day, particularly behind the departing impulse. Opted
to trim PoPs a bit lower in the afternoon compared to the morning to
reflect the departing wave and generally more stable conditions.
High temps were also scaled a bit lower for Saturday`s thicker
clouds and rain chances.
On Sunday, steady height rises initially are progged to be replaced
by another respectable trough in westerly flow. Favorable SE low
level flow ahead of this wave will maintain good PWATs of 1.5 to 2
inches from W-E across the CWA, so once forcing arrives later in
the day (along with a stalling cold front) we should see our next
good opportunity for rain and perhaps even some flooding.
Thereafter, westerly winds aloft will back more SW as mean
troughing occupies the western CONUS. Such a pattern looks
favorable for directing a monsoonal plume over West Texas, but
subtle day-to-day variations could easily hinder the otherwise
generous Superblend PoPs through late week. Opted to lower these
Superblend values a bit for obvious uncertainty, but max and min
temps look to fall close to climo most days.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
23/33
Area Forecast Discussion
National Weather Service Melbourne FL
852 PM EDT Fri Aug 11 2017
.DISCUSSION...
Currently/Tonight...The weak surface low continues to pull slowly to
the north of the area, which is allowing the surface ridge to build
across the southern peninsula. Sandwiched in between is a slug of
very high precipitable water around 2.2 inches. Diurnally driven
convection is diminishing but the high moisture and a few lingering
boundaries may continue to generate isolated-scattered showers
across the north. We have chance POPs there until midnight which
still seems prudent. A large area of stratiform rain across the
south third will gradually diminish through late evening.
Thereafter, the HRRR and local WRF don`t show any further precip
chances. With all the moisture in the atmosphere, considerable
cloudiness should linger through the night. Only minor changes have
been made to the previous forecast.
&&
.AVIATION...Lingering stratiform rain across the southern terminals
will diminish through late evening. Low levels will be very moist
but considerable debris cloudiness should preclude any significant
periods of low stratus. How long the cloudiness persists into Sat
will determine time of convective onset. Have gone with 17-18z for
now, but could be sooner in some spots if clouds break up quicker.
&&
.MARINE...
Tonight-Saturday....Weak surface low lifting north of the waters and
ridge building in across the south will gradually ease the pressure
gradient tonight and by Sat we should have a southwest wind flow 10
knots or less across the waters. This will result in rather benign
seas on Sat. Some strong storms should push off the coast in the
afternoon though.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Forecasts...Lascody
Radar/Impact Wx...Sedlock/Smith
Area Forecast Discussion
National Weather Service San Angelo TX
614 PM CDT Fri Aug 11 2017
.AVIATION...
/00Z TAFS/
VFR conditions will continue across West Central Texas terminals
through Saturday morning. A few of the high res models
(Specifically the HRRR) are showing a chance of showers and storms
moving across the area and its terminals n Saturday afternoon.
This not really supported by the other models or the current
forecast and will not include a mention of these storms at this
point. Have plenty of time to watch and update the late forecasts
if the trend of the HRRR continues. Otherwise, light winds will
prevail.
&&
.PREV DISCUSSION... /issued 345 PM CDT Fri Aug 11 2017/
SHORT TERM...
(Today and Saturday)
An upper level high centered over central Texas will lead to another
warm and mainly dry night across our area. An isolated shower or
thunderstorm, however, cannot be ruled across the northern Big
Country mainly north of I-20. Otherwise, expect mostly clear skies
with lows in the lower to mid 70s.
On Saturday, the upper high will remain centered across the southern
half of the CWA. Meanwhile, a frontal boundary draped across the Red
River will sag slowly southward and lie near the northern Big
Country by the late afternoon. Hi-res model guidance indicates
scattered thunderstorms developing mainly north of the I-20 corridor
along the boundary. The Storm Prediction Center does have Haskell
and Throckmorton counties outlined in a slight risk for severe
thunderstorms with the primary threat being damaging downburst
winds. Otherwise, expect another hot afternoon across the CWA with
highs in the mid to upper 90s.
LONG TERM...
(Saturday night through Friday)
A cold front is forecast to stall across North Texas Saturday
night, with shower and thunderstorms development across much of
North Texas/Oklahoma. Some of this activity may move into portions
of the Big Country, although the bulk of the convection will
remain north of the area. In addition, isolated to scattered
showers and thunderstorms are forecast to develop across West
Texas during the early evening hours. Some of this activity may
drift into western portions of the forecast area, before
dissipating by mid to late evening. A few of these storms may
become strong to severe, with hail, strong gusty winds, and
locally heavy rainfall being the main concerns.
Sunday into the first part of next week, scattered showers and
thunderstorms will once again be possible across North Texas in
association with the remnant cold front, with isolated to scattered
showers and thunderstorms possible across portions of West Texas due
to a continued surface trough. Some of this activity may approach
our northern and western counties during the late afternoon/evening
hours. The influence of an upper level ridge centered across South
Texas will preclude this activity from making it too far south and
east into the forecast area. Highs through this period will remain
in the mid to upper 90s, although a few locations may approach the
century mark. Overnight lows will mainly be in the mid 70s. Upper
level ridging will build back into the area for the middle to latter
part of the week, resulting in hot and dry conditions
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 75 98 75 98 / 10 10 30 20
San Angelo 74 100 75 100 / 5 5 10 10
Junction 73 98 74 99 / 5 5 5 5
Brownwood 74 99 75 99 / 5 10 10 20
Sweetwater 74 96 74 96 / 10 20 30 30
Ozona 73 96 73 98 / 5 10 5 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07
Area Forecast Discussion
National Weather Service Tulsa OK
853 PM CDT Fri Aug 11 2017
...UPDATE...
.DISCUSSION...
Forecast is largely on track for tonight, with only a few tweaks
to cloud cover required. Very isolated diurnal showers/storms
across far eastern Oklahoma and western Arkansas have dissipated
with sunset, and most areas should remain dry through the night.
The HRRR continues to show some development toward sunrise across
portions of southeast Oklahoma, in response to increasing low
level warm advection. The existing slight chance POPs should cover
this potential, as the better chances and greater coverage should
hold off until tomorrow. Updated products already out.
&&
.PREV DISCUSSION... /Issued 642 PM CDT Fri Aug 11 2017/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Few to scattered mid/high clouds should remain common across
Eastern Oklahoma and Northwest Arkansas overnight. Parts of far
Northwest Arkansas may develop some MVFR cig/vis early Saturday
morning...though conditions should lift back to VFR mid to late
morning Saturday. During the day Saturday...increasing mid and
high clouds are forecast to spread across the CWA with east to
northeasterly winds. Some precip chances could become possible
during the afternoon hours and have added a Prob30 group to MLC as
Southeast Oklahoma looks to have the greater potential.
PREV DISCUSSION... /Issued 321 PM CDT Fri Aug 11 2017/
DISCUSSION...
Overnight convection has essentially worked over the atmosphere
today and also shoved the synoptic boundary well south of the
forecast area. Thus...chances of any convective redevelopment the
remainder of the day will be slim.
Models continue to struggle with the placement of the heaviest
rainfall through the weekend/early next week...although current
indications point to the Red River area as the favored area
beginning late Saturday. The aforementioned frontal boundary is
expected to lift a bit north tomorrow...with increasing convection
north of the boundary by the afternoon as a well-defined mid-level
wave traverses the southern Plains. This activity should continue
to organize and peel east-southeast...impacting areas mainly
south of I-40 during the evening and overnight hours. Some severe
weather will be possible along with locally heavy rainfall given
forecast PWATs near 2 inches. Have held off on any flood headlines
at this time as the event is still a good 24-30 hours
away...although evening/overnight crew will need to revisit.
The GFS and ECMWF diverge significantly with their respective QPF
later Sunday into early Monday...with the GFS much farther north
with the axis of heavy rain. Will lean toward a farther south
solution at this time (essentially blending the two
solutions)...which places additional heavy rainfall along the I-40
corridor.
The upper pattern is expected to become a bit more southwesterly
going into mid-week...which should eventually lift the synoptic
boundary north of the area along with decreasing rain chances.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...22
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
531 PM MDT Fri Aug 11 2017
.DISCUSSION...(This Evening Through Friday)
Issued at 135 PM MDT Fri Aug 11 2017
Upper trough continues across the eastern half of the CONUS...while
ridging remains over the west coast. A series of shortwaves are
pushing southeast across the northern High Plains...all the way into
Canada. This will allow for active weather over the next couple
days. Storms have quickly developed over the last hour across
northeast WY and the Black Hills area. Models continue to show
relatively weak CAPE of 800-1200 J/KG and decent shear. A few storms
could end up severe...but generally most storms are expected to be
weak to moderately strong with small hail and gusty winds. HRRR
shows the developing line of storms moving eastward over the next 6
hours crossing the Black Hills area...then pushing into central SD
through the evening.
Surface high pressure across the MS Valley will keep south/east flow
across the area Saturday as a shortwave crosses the region. A
surface trough will straddle the CWA through the day with the best
instability across southwest to south central SD. MLCAPE of 1500-
2500 J/KG is expected with decent...but not great...shear. It will
enough for some storms to become strong to severe Monday afternoon
and evening. Highs will be in the 70s to low 80s. Upper wave will
push east of the area Sunday with drier weather expected. The ridge
axis will cross the northern plains Monday morning with southwest
flow developing by Monday evening. Another round of storms are
possible Monday evening with some severe storms possible as a strong
upper wave crosses the region along with a surface trough. Daily
chances for storms are expected next week as a broad upper trough
slowly crosses the region.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 526 PM MDT Fri Aug 11 2017
A broken line of thunderstorms will continue to shift east across
the southeast third this evening. Gusts to 45 knots will be
possible with these storms. Other isolated TS are possible across
NW SD this evening, with large hail and gusts over 45 knots
possible there. Local IFR conditions are possible with the
thunderstorms. There may be some patchy fog in the early morning
adjacent to the Hills. Otherwise, TS will develop once again
across western SD, esp scentral SD Sat afternoon. A few strong to
severe storms will be possible as well as local MVFR/IFR conds.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...13
AVIATION...JC