Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/18/18
Area Forecast Discussion
National Weather Service Bismarck ND
953 PM CDT Thu May 17 2018
.UPDATE...
Issued at 944 PM CDT Thu May 17 2018
Moderate rain with a few embedded thunderstorms continue across
far south central North Dakota and the James River Valley along a
stalled front that will lift north as a warm front overnight. The
CAMs through the 01 UTC HRRR continue to suggest a potential MCV
propagating north out of the South Dakota convection, likely
phasing with upstream impulses. The evolution of this feature
will be key to precipitation potential the remainder of the
overnight and into Friday morning especially across central North
Dakota. Will continue to monitor convection across northeast
Montana as of 0250 UTC with a corridor of greater elevated
instability. However, its survival to the North Dakota border is
somewhat uncertain.
UPDATE Issued at 646 PM CDT Thu May 17 2018
Cancelled Severe Thunderstorm Watch 102 with this update, as the
severe threat the remainder of the evening will remain across
north central North Dakota in association with the stalled front.
The CAMs through the 22 UTC HRRR, and the 18 UTC NAM/GFS continue
to suggest potential Mesoscale Convective Vortex (MCV)
development overnight that will propagate northeast out of the
South Dakota convection. This will be the focus for widespread
rain with a few embedded thunderstorms through the night into
Friday, especially across central North Dakota.
UPDATE Issued at 408 PM CDT Thu May 17 2018
Issued Severe Thunderstorm Watch 102 valid through 03 UTC for
Sioux, Emmons, Dickey and McIntosh counties. At this time,
significant cloud cover across southwest North Dakota will be a
limiting factor to the severe threat for these areas, however,
this will be closely monitored.
&&
.SHORT TERM...(This evening through Friday)
Issued at 237 PM CDT Thu May 17 2018
Convection ongoing with the morning activity cooling the surface
temperatures resulting in added Convective inhibition to overcome.
Currently teh thunderstorms over south central North dakota appear
to be elevated and less of a severe threat as a result of the
cooling.
Tonight, the thunderstorm complex expected to form over western
South Dakota will move northeast into Southwest and south central
North Dakota this evening and overnight and abundant rainfall
still expected across central North Dakota tonight. Isolated
severe potential still remains in place later this evening and
overnight.
Storm total rainfall of 1 to 2 inches still looks reasonable with
the abundant PW that models see. Overnight lows in the lower 40s
northwest to around 60 southeast.
Friday will see the best chance move north then diminish by
evening.
.LONG TERM...(Friday night through Thursday)
Issued at 237 PM CDT Thu May 17 2018
Scattered frost is still possible Saturday morning and Sunday
morning as a cold high pressure moves into the region. This may
eventually require a frost advisory for portions of teh north
central and southwest. Highs both days should be in the 60s to
lower 70s.
After that a slow moderating trend into the 70s will be seen
through the end of the week with slight chances for showers and
thunderstorms Wednesday and Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 944 PM CDT Thu May 17 2018
Rain with a few embedded thunderstorms will become more widespread
and move north through the evening and night through Friday
morning across central North Dakota. MVFR/IFR stratus across
northwest and north central North Dakota this evening will spread
south through the night, covering most of southwest and south
central North Dakota late tonight through most of Friday. Showers
and thunderstorms will be isolated across western North Dakota
tonight into Friday. Thunderstorms may redevelop across the James
River Valley, including KJMS, Friday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PA
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...PA
Area Forecast Discussion
National Weather Service Boston/Norton MA
1000 PM EDT Thu May 17 2018
.SYNOPSIS...
A weak cold front will move south across the region tonight
High pressure builds to the north Friday bringing dry but
cooler weather with northeast flow. Widespread rainfall,
locally heavy, on Saturday, followed by warmer and drier
weather Sunday and Monday although hit or miss
showers and thunderstorms possible Sunday. Unsettled conditions
may return Tuesday/Wednesday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
10PM UPDATE...
Dense fog has settled in across the Cape and Islands as light
offshore winds continue. Visibilities have dropped below a mile,
with Nantucket dipping below a half mile. A Dense Fog Advisory
has been issued for Nantucket until 8AM Friday.
The latest HRRR and CONSSHORT guidance suggests visibilities
will decrease northward throughout the night as an inversion
remains aloft. A cold front will push south across the region
around midnight with dry air following behind the boundary.
Visibilities will improve north to south inland by 10Z, but
this largely depends on when the dry air moves into the region.
Fog could linger on the islands past 12Z but should lift as
winds shift and strengthen out of the northeast.
Previous forecast remains on track.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Friday...
High pressure builds to the north and east which will advect
drier air from the north into SNE. Dry weather will continue
but NE flow and lingering low level moisture will result in
lots of clouds, especially south of the Pike with a bit more
sunshine to the north. Gusty NE flow will bring cooler temps in
the mid 50s to low/mid 60s, coolest along the coast where winds
will gust to 20-30 mph at times.
Friday night...
Old frontal boundary to the south will begin to push back north
toward SNE with deeper moisture slowly pushing into the region
overnight from the SW. Model trends are slower with onset of
overrunning rain as drier air hangs on longer. Rain should begin
to move in from SW to NE well after midnight, reaching NE MA
Sat morning.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
*/ Highlights...
- Moderate to heavy rain Saturday
- Showers, maybe a shot at storms early to midday Sunday
- Potential midweek wet-weather
*/ Overview...
It`s Spring. Persistent Baffin Bay low neighbored by the beginnings
of a Bermuda high. Meanwhile upstream, Aleutian low promoting NW N
America ridge, often SW CONUS cutoff lows. With Aleutian low death,
pattern snaps, ejects E, promoting a S-dip of N-stream energy round
the Baffin Bay low. Cool air pushed SE over the NE CONUS, shower
chances, chilly. However, the pattern can come together promoting
heavy rain / convective elements when any present SW CONUS cutoff
low pushes E as well, drawing N/E warmer air and/or tropical energy
with aiding Bermuda high, as was the case May 15th with a line of
severe weather, and as is the case this weekend with a heavy rain
threat. Ebb and flow otherwise, periods of active weather, with
persistent NW flow throughout in Baffin Bay low vicinity wobbles
against the Bermuda high. Will hit on targets of opportunity below.
*/ Discussion...
Saturday...
Moderate to heavy rain. Ejecting E Pacific-energy / SW CONUS low, as
N-stream vortmax dips S round Baffin Bay low. Draw N +2-3 standard
deviation precipitable water and specific humidity, clash of rich,
deep column moisture pressed by confluent low-level jet beneath H3
diffluent motions. Stronger low-mid level frontogenesis along warm
front appears focused over E Great Lakes ahead of H85 parent low,
lifting over Michigan into S Canada perhaps keeping us out of worst
threat. However decent isentropic upslope along 290-310K surfaces /
warm front, can`t rule out a decent slug of rain. Precipitable water
upwards of 2-inches, deep column moisture up to H3-4, freezing level
heights up around 14 kft with decent lift / ascent apparent, warm
rain processes possible. Fairly soaked already. However, RFC FFG
guidance roughly 2.5 to 3.5 inches for both 3- to 6-hour periods,
respectively. With fast 0-6 / 0-10 km flow, non-training, have low
confidence in widespread flood threats. Perhaps isolated urban /
poor-drainage issues. Will note in hazardous weather outlook. Per
tropical connection, isentropic motions, heaviest rains focus N/W
likely aided by S-facing slopes of high terrain per orographic
forcing of +2-3 standard deviation S low-level jet.
Low clouds and/or fog along with breezy S/SW winds likely to impact
S-coastal New England through this event. Higher dewpoint air over
still cool waters, definite potential for dense fog. Saturday into
Saturday night potentially continuing into Sunday morning with non-
diurnal temperature trend.
Sunday...
Late morning thunderstorms? Brief warm sector ahead of N-stream vort-
max S-dip. Perhaps upwards of several hundreds J/kg MLcape beneath a
parent low-mid level trof boundary / surface cold front. Low-level
forcing apparent, if enough MLcape within modest bulk shear, can`t
rule out some storms, isolated wind threats. But with late morning
timing am skeptical. Modest shear over weak MLcape, forcing along
the front more likely to get things organized over S/E New England
late morning but thinking scattered to a line of showers with some
embedded heavier rains. If model guidance suite is correct, we clear
out and dry out late day. Cold front timing crucial, must watch.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Friday Night/...High confidence.
Tonight...
IFR-LIFR with low stratus / fog S of BVY-HFD line. Highest
confidence S-coastal terminals, especially ACK with lowest
conditions, through roughly 6-10z, and 12z at the latest for
ACK. Light winds with IFR-LIFR conditions, shifting N winds,
becoming quickly breezy and immediately VFR.
Friday...
MVFR cigs may linger through the morning near the south coast
with patchy IFR over the islands. Otherwise VFR cigs. NE wind
gusts to 25 kt along the coast. Dry weather.
Friday night...
Conditions lowering to MVFR/IFR along the south coast, then
spreading northward toward daybreak. Rain developing from SW to
NE well after midnight.
KBOS Terminal...Moderate confidence in TAF. There is a risk of
MVFR-IFR cigs redeveloping close to midnight. Will hint with
SCT008 in collaboration with ZBW. NE wind gusts 20-25 kt
developing after 06z.
KBDL Terminal..High confidence in TAF. Hold VFR.
Outlook /Saturday through Tuesday/...Moderate confidence.
Saturday: Mainly IFR, with local MVFR possible. Breezy. RA
likely, patchy FG.
Saturday Night: Mainly IFR, with local MVFR possible. Breezy.
Chance RA, chance SHRA, patchy FG, slight chance TSRA.
Sunday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA, slight chance TSRA.
Sunday Night through Monday: VFR.
Monday Night through Tuesday: VFR. Chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Friday Night/...Moderate confidence.
Surge of increasing NE winds developing late tonight behind a
cold front and continuing during Friday with strong pressure
gradient in place. Gusts to 25-30 kt and SCA will continue.
Seas gradually building late tonight through Friday. Winds
diminish somewhat Friday night, but still gusty over south
coastal waters. Areas of fog will reduce vsbys tonight,
especially south coastal waters.
Outlook /Saturday through Tuesday/...Moderate confidence.
Saturday: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain, patchy fog. Areas of visibility 1 nm or less.
Saturday Night: Winds less than 25 kt. Local rough seas. Chance
of rain, chance of rain showers, patchy fog, slight chance of
thunderstorms. Visibility 1 nm or less.
Sunday: Winds less than 25 kt. Areas of rough seas. Slight
chance of rain showers, slight chance of thunderstorms, patchy
fog. Local visibility 1 to 3 nm.
Sunday Night: Winds less than 25 kt. Local rough seas.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Monday Night through Tuesday: Winds less than 25 kt. Chance of
rain showers.
&&
.TIDES/COASTAL FLOODING...
Astronomical tides are high for the early Friday morning tide
cycle. Boston tide is 11.8 ft. With developing NE flow, may see
a surge 0.3 to 0.5 ft along the east coast. Despite light seas,
elevated water levels may result in minor splashover for the
typical low lying areas prone to tidal flooding along the
eastern MA coast.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until 8 AM EDT Friday for MAZ024.
RI...None.
MARINE...Small Craft Advisory from 4 AM Friday to 2 AM EDT Saturday for
ANZ232>235-237.
Small Craft Advisory from 4 AM to 2 PM EDT Friday for ANZ230-
236.
Small Craft Advisory from 2 AM to 5 PM EDT Friday for ANZ231-
251.
Small Craft Advisory from 2 AM to 8 PM EDT Friday for ANZ250.
Small Craft Advisory from 4 AM Friday to 8 AM EDT Saturday for
ANZ254>256.
&&
$$
SYNOPSIS...KJC/Sipprell
NEAR TERM...Belk/KJC/Correia
SHORT TERM...KJC
LONG TERM...Sipprell
AVIATION...Belk/KJC/Sipprell/Correia
MARINE...KJC/Sipprell
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Dodge City KS
657 PM CDT Thu May 17 2018
...Updated Aviation Section...
.SHORT TERM...(This afternoon through Friday)
Issued at 1213 PM CDT Thu May 17 2018
Gearing up for severe weather operations later today and again on
Friday/Friday night.
Surprise convection that developed earlier this morning is
weakening rapidly. We are expecting it to be quiet for several
hours now, through about 4 pm, as SE winds increase markedly and
instability mounts. CAPE in excess of 3000 J/kg is expected across
along and west of US 83 by peak heating. Thunderstorms are
expected to initiate along the KS/CO border around 5 pm, and
subsequently spread eastward across SW KS this evening, reaching
Highway 283 by 9 pm. Many CAMs, HRRR and 12z NAM all show
convection remaining largely discrete/supercellular, which will
greatly enhance very large hail potential (up to 3" in diameter).
SPC has expanded severe probability and upgraded risk for large
hail, and we concur. Regarding tornado potential, low level shear
and moisture quality are less than optimal, keeping the risk low.
This said, we are talking about discrete supercells in SW KS in
May, during the early evening when SE 850 mb winds increase to
30-40 kts. A tornado can`t be ruled out, but clearly hail is the
primary threat through this evening. Maintained a severe hail/wind
mention in the forecast mainly west of US 283 through this
evening. Increased pops into the likely category for several hours
this evening. Weakening storms will progress through the eastern
zones later tonight. There is uncertainty regarding the rate of
decay, as moisture quality will only be improving with eastward
extent and time. Regardless, expect most/all activity to clear SW
KS by sunrise Friday morning. Radiational cooling will be very
poor tonight, with moist SE flow persisting, holding most
locations in the lower 60s.
Another active severe weather day is expected on Friday. Details
are still emerging. Of note, a trend toward a slower solution
continues, with 12z NAM now trending its surface low SW toward
Clayton, New Mexico by 7 pm. This is close to the ECMWF`s
continuity, placing its surface cyclone near Elkhart 7 pm Friday.
This slightly slower solution will give moisture quality some
additional time to improve, with initiation not expected until the
7 pm time frame along the US 83 corridor. Moisture quality will be
less than pristine (less than what we can normally get from the
Gulf of Mexico in May). Moisture depth in the boundary layer will
be less than optimal as seen from forecast soundings. Still, ECMWF
continues to spread low to mid 60 dewpoints into the eastern CWA,
and lower 60s can be expected along the dryline/triple point at
initiation time Friday evening. CAPE of 2-3k J/kg will be common,
with convergence and shear assisting in triggering and organizing
convection. The threat for tornadic supercells remains, with the
threat area trending SW with time. Excellent lapse rates will
continue to support huge hail from any discrete activity.
Otherwise, strong SE winds will continue moisture advection
through the daylight hours Friday, with highs again in the 80s.
.LONG TERM...(Friday night through Thursday)
Issued at 137 PM CDT Thu May 17 2018
Very little time spent on the long term, given severe weather
threatening today and Friday. Model blend from forecast builder
was largely accepted, with small chances of showers and
thunderstorms virtually every day except Sunday.
Closed low over northern Utah Friday PM ejects rather quickly into
Nebraska on Saturday. Vast majority of associated shower and
thunderstorm activity will be north of SW KS by Saturday, with
gusty W/NW winds and modestly cooler temperatures. Some wraparound
rain showers will likely clip the I-70 corridor.
Broad shortwave ridging on Sunday, delivering a beautiful spring
day and dry weather. Pleasant highs in the 70s with light winds.
Monday into next week, 12z ECMWF displays a rather odd pattern for
May, with a large scale but relatively weak closed low enveloping
the SW US. 568 dm low near Los Angeles Monday afternoon
essentially sits and spins to Las Vegas Tuesday, before weakening
and lifting north through the Rockies. Broad SWly flow aloft will
prevail over the plains as a result, with numerous embedded
shortwaves triggering virtually constant small chances of daily
convection. Given it`s May, some severe weather potential will
have to be evaluated day-to-day, as shortwaves/jet maxima interact
with the dryline and moisture supply. Temperatures will show
little diurnal change, with highs in 80s and lows in the 50s and
60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 653 PM CDT Thu May 17 2018
The main question is whether strong/severe convection will impact
terminals through the early part of this TAF period. Earlier
indications were that storms would grow upscale into one or two
clusters later on in the evening, but the convective coverage
through 23z has been lower than expected. If there is growing
confidence that storms will likely not impact GCK and/or DDC, then
TAF will need to be amended to remove VCTS. Otherwise, southeast
winds will continue through the night at 10 to 15 knots, picking
back up late morning through afternoon to around 20 knots
sustained. More thunderstorms are likely to impact at least one or
two of the terminals just beyond this TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 62 86 61 81 / 60 30 30 10
GCK 61 88 57 74 / 60 50 30 10
EHA 60 90 56 77 / 40 10 10 10
LBL 64 91 60 81 / 60 50 10 10
HYS 63 84 61 77 / 30 30 40 30
P28 65 88 66 89 / 20 20 30 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Umscheid
Area Forecast Discussion
National Weather Service North Platte NE
634 PM CDT Thu May 17 2018
.SHORT TERM...(This evening through Friday)
Issued at 344 PM CDT Thu May 17 2018
An upper trough was positioned across the Great Basin late this
afternoon. Disturbances on the downstream side of this trough
along the Central and Northern High Plains will lift northeast
overnight. Across western Nebraska, scattered thunderstorms in the
panhandle will move east and should expand in coverage. A low
level jet is expected to sustain thunderstorm development. The
latest HRRR and NAM models do not develop deep convection
southward into southwest Nebraska. However, southeastward
development is expected. Any storms this evening would favor
large hail and gusty winds, with a transition more towards brief
heavy rain and gusty winds as system coverage increases. Much of
the thunderstorms should remain west of highway 83 before
midnight, then progress eastward overnight. With the atmosphere
fairly moist with precipitable water values from an inch up to
1.25 inches, locally heavy rainfall over an inch is possible.
On Friday, scattered showers are expected mainly east of highway
83 during the morning, with a chance further west. In the
afternoon, thunderstorms expected to develop, especially after
21z, ahead of the advancing upper trough. Focus will be along a
weak front aloft, with models indicating initiation from between
Valentine through Bassett south through Mullen and Thedford. A few
storms by late afternoon could be severe.
.LONG TERM...(Friday night through Thursday)
Issued at 344 PM CDT Thu May 17 2018
The upper trough will advance into most of western Nebraska as a
closed lows deepens in northeast Colorado. Likely to categorical
POPs with widespread showers and thunderstorms expected as a cold
front advances southeast overnight. With precipitable water values
remaining high up to 1.25 inches, and fairly widespread showers
and thunderstorms, areas of heavy rainfall expected. One to 1.5
inches of rainfall is forecast most of the forecast area, with
local amounts near 2 inches. Chances increase that at least
localized minor flooding will occur. A few storms could also be
severe during the evening.
On Saturday and Saturday night, the upper trough and closed low
will move across. While strong or severe storms are not expected,
the threat for showers and a few thunderstorms will continue.
Additional rainfall of a quarter to half inch is expected, with
locally up to an inch possible. Therefore, some continued chances
for heavy rainfall and localized minor flooding could continue.
Much cooler, with highs from the upper 40s to lower 50s
northwest, to near 60 far southeast.
Sunday, morning shower chances remain across the east as the
system begins to exit the area. Highs should reach the lower 60s
most areas.
Mainly dry Sunday night into Monday as temporary upper ridging
develops across the Central Plains. Chances for showers and
thunderstorms return Monday night through Thursday of next week,
as an upper trough in the western U.S. keeps gulf moisture in
place across the region. Upper flow begins the period fairly
zonal, then more southwesterly as the upper trough lifts
northeast. Highs warm from the low 70s Monday, to the upper 70s to
around 80 Tuesday through Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 631 PM CDT Thu May 17 2018
Thunderstorms will organize and move east across the area this
evening and overnight. Areas of MVFR can be expected where
thunderstorms occur. Otherwise some lower ceilings and MVFR
conditions can be expected Friday morning prior to 18Z. Low level
wind shear will also be a concern tonight as a southerly low level
jet increases to 50 kt.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Taylor
Area Forecast Discussion
National Weather Service Melbourne FL
825 PM EDT Thu May 17 2018
.UPDATE...
Line of fast-moving showers and isolated storms from Osceola
southward into Okeechobee county will continue to push eastward
from Brevard southward to the Treasure Coast this evening. Areas
farther north and inland can expect occasional light to moderate
rain through this evening. Have only made minor adjustments to
PoP/wx grids based on radar trends and short-term guidance.
Most precipitation should be over with by midnight but will keep a
slight chance of showers in with the HRRR and local WRF showing a
few showers developing overnight. Lows will be in the low 70s
along the coast and around 70 inland.
&&
.AVIATION...
Line of showers will move through MLB-SUA this evening with brief
MVFR cigs around 1500-2000ft and visibilities in the 3-5 SM range.
VCSH all other sites with most precip expected to end by 04Z. VFR
expected overnight. Another wet day expected on Friday with
numerous showers and storms expected in the afternoon.
&&
.MARINE...
8 p.m. observation from buoy 41009 shows seas of 3 feet and winds
around 10-12 kt. Seas 2-3FT nearshore, 3-4FT offshore and up to
5FT in the Gulf Stream north of Sebastian Inlet from previous
forecast look right on track. No changes will be made.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 71 81 73 82 / 30 80 40 60
MCO 72 85 72 86 / 40 70 30 70
MLB 73 81 74 81 / 60 80 40 60
VRB 73 81 75 81 / 60 80 40 60
LEE 72 85 72 85 / 30 70 30 70
SFB 71 84 71 85 / 30 70 30 70
ORL 72 85 72 85 / 30 70 30 70
FPR 73 81 75 81 / 60 80 40 60
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Combs/Spratt
Area Forecast Discussion
National Weather Service Raleigh NC
945 PM EDT Thu May 17 2018
.SYNOPSIS...
An area of low pressure will drift slowly northward across the
Southeast U.S. through Friday, bringing an increased threat for
showers and few thunderstorms to central NC.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 945 PM Thursday...
Deep cyclonic southerly flow continues to draw moist air into NC,
with PW holding at 150-200% of normal in the area and upstream. 00z
upper air analyses depict the mid level low over MO, with the lower
level circulation center further SE between Tupelo MS and Muscle
Shoals AL. A subtle/weak southerly upper jetlet over N FL across GA
will translate northward into the S Appalachians tonight, boosting
weak upper divergence the region, while in the low levels, the 925
moisture transport maximum will surge into central and eastern NC.
The greatest shower and isolated storm coverage in the last several
hours has been between the Highway 1 and I-95 corridors, at the nose
of the northwest-pushing 925 mb jet, and as this continues to
translate to the NW, as the HRRR has indicated, the band of showers
should continue a NW translation through the CWA, reaching the NW
Piedmont late tonight. Otherwise, while moisture remains plentiful,
there is little dynamic support for strong ascent, so any other
showers should be scattered and disorganized, with a diminishing
storm threat given weak to absent deep layer shear, dwindling CAPE
with nightfall, and poor mid level lapse rates. Will keep a band of
likely to categorical pops tracking to the NW overnight, while
maintaining at least chance pops elsewhere, with isolated storms for
another few hours. Another sticky night, with lows in the upper 60s
to lower 70s. -GIH
Earlier discussion from 315 PM: Afternoon convection is a little
less than earlier anticipated, and this may be attributed to one or
two factors: 1.) Minor perturbation aloft lifting north-northeast
from central SC into central NC. The best lift associated with this
feature occurring to its east and north, or essentially along and
east of highway 1; 2.) cluster of showers and storms over north
central SC disrupting the 850mb moisture transport into central NC,
cutting off the better inflow into the Piedmont.
As the upper level feature lifts farther east-ne, 850mb moisture
transport should become re-established this evening, leading to a
likely uptick in convective coverage this evening. With loss of
heating, should see a downward trend late this evening into the
overnight. That being said, the abundantly moist air mass and the
relatively close proximity of the upper level low over the Mid-
South, a threat for scattered showers will persist through the
night. The showers and storms will be efficient rain producers
thanks to the available moisture, and with the deep sly flow, the
convection will train repeatedly over the same location. This may
lead to minor flooding of streets and low lying areas.
Overnight temperatures in the upper 60s-lower 70s.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 315 PM Thursday...
The weather pattern changes little Friday and Friday night as the
mid-upper level low traverses slowly east, and maintains a deep sly
flow over central NC. Perturbations in this flow should trigger
numerous showers and storms, especially during the heat of the
afternoon into the evening hours. Coverage Friday afternoon-evening
may be enhanced by a decent perturbation or s/w depicted by the
majority of the models, lifting newd from SC. If this materializes,
a steady band of convection may result, increasing the threat for
locally excessive rainfall. Based on expected sfc pattern, the
Piedmont counties may be more under the gun through Friday
afternoon, with the heavy rain threat shifting east into the Coastal
Plain Friday night. Will hold off on the issuance of a Flash Flood
Watch at this time, and see where the heavy rain occurs tonight, and
see if models begin to indicate a stronger signal (such as stronger
low level convergence) for Friday-Friday afternoon.
Extensive cloudiness and scattered/numerous convection will hold
temperatures mainly in the 70s to around 80 Friday afternoon.
Overnight temperatures Friday night in the 65-70 degree range.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 255 PM Thursday...
The long term period will feature a gradual easing of the ongoing
wet pattern into more scattered rain chances as we head into
the middle of next week.
The start of the long term period will feature an amplified pattern
with the sub-tropical ridge off the southeast coast and a
shearing trough across the OH and TN Valleys. A deep southerly
flow will drive an axis of convection across central and eastern
NC on Saturday that will shift east on Sunday. Fairly
widespread showers and thunderstorms are expected on Saturday
with a bit less coverage and a greater focus to the east on
Sunday. While the trough departs early next week, a weakness
aloft persists on Monday and Tuesday that will support more
scattered, mainly afternoon and evening showers and storms. The
approach of a backdoor cold front late Tuesday into Wednesday
will support scattered storms with a drier air mass reducing
storm coverage on Thursday. With very little air mass change, a
good deal of cloudiness and at least scattered convection, highs
will consistently range in the lower to mid 80s with low mainly
in the mid to upper 60s. -Blaes
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 745 PM Thursday...
24 hour TAF period: A lot less coverage of precipitation this
evening with moderate rain across the southern counties and a few
lighter showers mainly across the eastern half of the forecast area.
Scattered showers will continue overnight with little to no thunder
expected at any TAF site. Ceilings will drop overnight to MVFR and
then IFR with a low chance of LIFR conditions possible before
sunrise. Gradual lifting of ceilings after sunrise is expected but
depending on precipitation distribution, sub-VFR conditions could
occur at any time during the 24 hour TAF period. Another round of
showers and thunderstorms with southwesterly winds expected on
Friday.
Long Term: Sub-VFR conditions possible each day with showers and
thunderstorms expected each day through the long term. By Monday,
moisture transport into the area will decrease and coverage of
precipitation could become more widespread.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...WSS
NEAR TERM...Hartfield/WSS
SHORT TERM...WSS
LONG TERM...BLAES
AVIATION...Ellis
Area Forecast Discussion
National Weather Service Springfield MO
659 PM CDT Thu May 17 2018
.SHORT TERM...(This evening through Friday)
Issued at 203 PM CDT Thu May 17 2018
A couple of upper level disturbances continue to affect the area.
Early on today the more prominent disturbance over AR was
producing some some heavier rainfall amounts in south central MO with
some slow rise flooding possible in some areas. The atmosphere
has stabilized in that area but will need to watch for some
additional convection drifting in from the southeast.
Another disturbance has moved south into west central MO with
fresh convection popping up over the past couple of hours north of
KSGF. The disturbance will drift southeast today and tonight and
we will continue to see showers/thunderstorms, particularly north
and east of the upper disturbance. Could see a stronger brief
pulse storm or two with hail and wind the main risks. With slow
moving storms, pockets of heavy rain and localized flooding will
be a continued concern.
The HRRR radar simulation does weaken convection this evening and
overnight as the upper disturbance drifts off to the east. Some
showers may linger over the eastern cwfa for a time.
With a shortwave ridge moving into the area Friday, convective
coverage looks to be more sparse, but some diurnal convection
chance will linger over the eastern cwfa.
.LONG TERM...(Saturday through Thursday)
Issued at 203 PM CDT Thu May 17 2018
The shortwave ridge will shift off to the east with another
disturbance and associated weak sfc low moving from the Plains
into IA/western IL by Sunday night. The weakening trailing sfc
cold front will gradually become a west-east oriented boundary
that drifts into the area Monday. Guidance varies with subtle
features by this time, but there looks to be some rain/tstms
chances continuing into the midweek period with upper level
disturbances in the weak upper level westerlies. Definitely a
continuation of a late June type pattern versus stronger May type
systems.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 657 PM CDT Thu May 17 2018
Pilots can expect prevailing VFR conditions at area terminals
through Thursday but will have to monitor for potential MVFR to
locally IFR conditions late tonight. Expect to see patchy to
perhaps areas of fog and low stratus late tonight into early
Thursday morning. Otherwise VFR conditions will prevail by
Thursday afternoon.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...DSA
LONG TERM...DSA
AVIATION...Foster
Area Forecast Discussion
National Weather Service Las Vegas NV
859 PM PDT Thu May 17 2018
.SYNOPSIS...Scattered showers and isolated thunderstorms are
possible in the eastern Sierra and central Nevada through Saturday
evening. An isolated shower is still possible in the same locations
on Sunday. Temperatures primarily over northern Lincoln County and
in the eastern Sierra this evening and again Friday afternoon.
Temperatures will trend upward a degree or two each day through
Sunday.
&&
.UPDATE...Can not rule out a few light rain showers overnight
across northern Inyo, Esmeralda, central Nye and Lincoln Counties on
backside of upper low. The rest of region will stay dry with some
increase in cloud cover across southern Nevada. Update out soon.
&&
.DISCUSSION...through Thursday.
An upper low continues to move slow to the east across White Pine
this afternoon. So far showers and thunderstorms have been limited to
northern Nye and White Pine Counties. Clouds have been relatively
flat so far in northern Lincoln County. Still anticipated the
potential for some showers on the back side of the low but will
likely be fairly limited. The recent HRRR runs continue to show the
potential for showers in the northern portions of Inyo County and
Esmeralda County, primarily over the higher terrain throughout the
evening. Gusty winds will occur over San Bernardino County this
evening with gusts of 30 to 40 mph. Lingering moisture and
instability will provide a chance for showers in northern Lincoln
and eastern Sierra again on Friday afternoon. The next weak wave
will move across central California the area on Saturday afternoon
providing another chance of showers and isolated thunderstorms from
the eastern Sierra through Esmeralda, central Nye and Lincoln
Counties on Saturday afternoon. A shower couldn`t be ruled out in
the Spring Mountains as well.
An upper low will be dropping down the California coast on Sunday
night into Monday providing an increase in south to southwest winds
on Monday afternoon across the area and a chance of showers and
thunderstorms to Inyo and Esmeralda Counties on Monday. The models
are in good agreement with the low moving into southern Nevada on
Tuesday and then lingering in the area into Wednesday. Moisture will
be limited but showers and thunderstorms will be possible across the
eastern Sierra and over the higher terrain of southern Nevada on
Tuesday. There are some differences on how quickly the upper low
fills and/or moves to the east. Temperatures will cool a few degrees
with the upper low on Tuesday and Wednesday but will remain near the
seasonal normals through the period.
&&
.AVIATION...For McCarran...Light, variable wind will continue
through through the afternoon then transition to southwesterly flow
between 6-12 knots through the evening and overnight. Light,
variable winds will prevail Friday morning. By the afternoon, east-
southeast winds between 4-8 knots. Typical drainage wind overnight
into Saturday morning. Prevailing VFR.
For the rest of southern Nevada, northwest Arizona and southeast
California...Outside of KBIH, west to southwest winds will hold
through the evening. At KBIH, gusty north winds will persist through
late evening. Friday, winds will be 10-20 and follow typical diurnal
trends. Strongest winds develop across the western Mojave Desert and
KDAG. FEW-SCT skies with CIGs at or above 15k feet, except at KBIH
where CIGs may drop to 10k feet this evening.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
Discussion...Czyzyk
Aviation...Boothe
&&
$$
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