Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/20/19
Area Forecast Discussion
National Weather Service Bismarck ND
1042 PM CDT Tue Mar 19 2019
Issued at 1042 PM CDT Tue Mar 19 2019
With the latest HRRR/RAP/GFSLAMP trending with little to no
stratus central ND late tonight through Wednesday morning, have
opted to improve sky grids to clear/partly cloudy, and warming
afternoon high temperatures across central ND. Still cooler
across the James River Valley where the cooler 925mb-850mb
temperatures will reside.
UPDATE Issued at 917 PM CDT Tue Mar 19 2019
Latest 00Z NAM and high resolution model guidance not as aggressive
with light freezing drizzle potential, thus will leave the previous
forecast as is. The NBM and HRRR still fairly pessimistic with
higher low level RH fields working their way north to south overnight
and lingering through the day Wednesday, resulting in plenty of
clouds for central ND. The RAP has been trending with less RH and
consequently less clouds for central ND. Believe the previous forecast
has the correct trends overnight through most of Wednesday morning.
At this point, will continue to monitor upstream observations overnight
and assess the rest of the 00Z data to get a better handle on what
is to come for Wednesday afternoon. No changes with this update.
UPDATE Issued at 640 PM CDT Tue Mar 19 2019
Latest surface map shows a warm front/southern Manitoba and cold
front/central central Manitoba, with pressure falls occurring
well ahead of it into most of North Dakota. High clouds this
evening are forecast to be replaced by stratus after midnight,
dropping from north to south. High 925mb RH fields evident on the
models and can be seen on the visible satellite imagery loop over
northeast Manitoba. Concern now is for patchy light freezing
drizzle as enough weak upward vertical motion is being advertised
in the BUFKIT soundings per GFS/NAM/RAP/HRRR as well in the high
resolution ARW/NMM. However not all models develop precipitation
as the cloud depth needed for light freezing drizzle (at least
3200ft thick) and upward vertical motion/omega (at least -5 microbars
/sec) are marginally being met. Will monitor the upstream stratus
and look more into the 00z data/soundings for possibly adding a
mention of light freezing drizzle. Current forecast is on track.
.SHORT TERM...(This evening through Wednesday)
Issued at 318 PM CDT Tue Mar 19 2019
A western upper level ridge and a northern Hudson Bay low will keep
northerly upper level flow across North Dakota. A mild pacific
airmass will be maintained west/southwest of North Dakota, while the
cooler air of the Hudson Bay low will persist to our north and east.
Currently, an h850 warm front was moving southeast across the state
following this morning`s cold front, with mainly clear skies over
western ND but high level clouds moving southeast across Manitoba
into central and eastern ND. This will be followed by another upper
level shortwave and h850 cooling tonight...with the upper level low
moving southeast across western Ontario into the Great Lakes, and
mainly affecting central and eastern North Dakota with some lower
and mid level clouds and cold advection. Models are suggesting the
lower stratus clouds may even reach portions of western North Dakota
late tonight and Wednesday morning, and lingering in central North
Dakota for most of the day.
The northwesterly, then more northerly winds expected tonight with
this system help prohibit fog formation tonight. Regarding any
precipitation, the main forcing associated with the upper level
shortwave should mainly affect areas to the east of North Dakota.
The forecast cloud cover will act to keep temperatures from dipping
into the teens tonight, but the now-expected stratus cloud cover on
Wednesday will have a big effect on expected high temperatures
Wednesday. Still expecting temperatures to reach into the lower/mid
40s in the far west, but temps should remain in the 30s in central
North Dakota with cloud cover lingering until later in the
.LONG TERM...(Wednesday night through Tuesday)
Issued at 318 PM CDT Tue Mar 19 2019
A roller coaster in temperatures for the long term forecast period
with chances of rain/snow Saturday-Sunday. This pattern will be very
favorable for widespread snow melt across western North Dakota. We
expect to begin to see some rises on rivers and streams as water
from the melt begins to flow into the system.
Warm advection kicks in for Thursday as the stratus clouds and
cooler air on Wednesday exits the area Wednesday night. We should
see highs Thursday from the upper 30s/lower 40s in the James
Valley...to the 40s over the rest of central ND, and upper 40s/lower
50s in western ND under mostly sunny skies.
On Friday another intrusion of cooler air from central Canada will
keep temperatures in the 35-40F range over central ND and in the mid
and upper 40s in the west.
Saturday...A developing low pressure system over the 4-corners will
develop on Thursday and Friday, despite the upper ridge that reaches
well north into western Canada. The models are in better agreement
developing the low northward along the Front Range of
Colorado/Wyoming Friday night, reaching the border of MT/SD/WY on
Saturday. This will bring mild temperatures to western and central
North Dakota, but also a chance of rain during the day and rain/snow
Saturday night as the low meanders eastward into eastern SD/NE
Saturday night and Sunday.
On Sunday, look for cooler conditions with brisk northerly winds as
cold air from central Canada plunges southward. Expect highs Sunday
from the 30s over central ND to the lower 40s in the far west, with
chances of rain or snow across southern ND...and lows Sunday night
in the teens and lower 20s.
After another cool day Monday, warmer conditions expected on
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 1042 PM CDT Tue Mar 19 2019
A weak cold front is forecast to move from central Manitoba and
just graze central ND overnight. Behind the cold front will be an
area of stratus, likely impacting KJMS late tonight through
Wednesday morning. As of this update, the stratus may or may not
continue through Wednesday afternoon at KJMS. Will know more with
the 06z taf issuance. The rest of the terminals are expected to
remain in VFR conditions.
Area Forecast Discussion
National Weather Service Wilmington NC
1006 PM EDT Tue Mar 19 2019
Developing low pressure off the SC Coast tonight will move
northeast along the immediate NC Coast Wed into Thu. Patchy
light rain along the coast late tonight, will become more
widespread and push further inland during Wed. The rain will end
early Thu as the low lifts further north, away from the forecast
area. A cold frontal passage will occur late Fri followed by
seasonable high pressure for the weekend. A frontal boundary
accompanied with scattered showers will slowly drop south
across the region early next week.
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 830 PM Tuesday...Latest HRRR and HiResW indicate patchy
light rain late tonight and will back the rain potential to late
tonight in the 15 to 24 percent range with the hier side of
this range along the immediate NC coast and adjacent waters. The
inland SC zones should remain mostly dry. Protected areas from
north-northeast winds west of the I-95 corridor could see
patchy frost before more opaque ci moves in as well as low
level stratocu from the east. Sfc dewpts will be in the upper
20s to low 30s and do expect up to 5 degree sfc dewpoint
depressions. Winds may briefly go calm or decouple at the far NW
portions of the FA but overall do not expect a widespread
frost with min temps dropping to 36 to 39 degrees. This may
require a SPS.
As of 300 PM Tuesday...Tricky forecast on tap for the near term
period. First off, with temps mainly just getting down into the
upr 30s tonight (mid 30s though in coldest spots), not
expecting much in the way of frost with ~5 kt wind and dewpoints
down in the upr 20s. Exception may be over far western areas
where patchy frost is possible. Surface high pressure north of
the area this aftn slides offshore tonight. Meanwhile, coastal
low pressure gradually develops just offshore through Wednesday
as a mid-level shortwave trough approaches from the west. Result
will be increasing chances of rain from east to west through
the day Wednesday, continuing into Wednesday night, in response
to increasing low-level convergence and isentropic upglide. PoPs
increased to 60-70% for eastern areas where the rain may be
moderate to possibly heavy at times. As for temps, expect only
highs in the 50s Wednesday due to NE flow and a cloudy sky. Lows
temps Wednesday night mainly 40-45. &&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 300 PM Tuesday...Surface low will lift off to the
north as potent shortwave crosses the Carolinas on Thursday. Any
lingering pcp from sfc low will move out of the area Thursday
morning. Dry air will wrap around the back end with some
clearing through the day, but mid to upper shortwave will ride
through later in the day with mainly clouds, but may see some
light pcp mainly to the north of local area over NC. Deep NW
flow will develop through Thurs night on back end of shortwave
moving out of area. This will give a little punch of CAA.
Overall, expect some clouds mixing with sun and low end pcp chc
on Thurs, but weather improving through Thurs night. Temps
should be near seasonable through the period with overnight lows
in the 40s and
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 PM Tuesday...High pressure will build in slowly from
the west and will migrate eastward through the weekend at the
same time as mid to upper ridge builds over the area. Overall,
expect a dry weekend with plenty of sunshine and warming temps.
The dry air mass in place will allow for some large diurnal
temp swings with afternoon highs just above normal and overnight
lows just below.
The center of the high will shift off shore Sunday night into
Monday. This will produce a southerly return flow which will
help to increase the temps and moisture, leading to some clouds
mixing with the sunshine on Monday, but temps warming into the
70s. By Mon night into Tues, mid to upper trough will dig down
over the Southeast. This will help to deepen sfc low as it
tracks east toward the coast while at the same time, a cold
front will drop down from the north. This will help to spread
clouds and pcp into the Carolinas Mon night into midweek. Cooler
air behind the front will drop temps quite a bit for Tues.
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 00Z...Low pressure developing off the SE US coast will move
northward overnight. This has already started to bring in a mid-
level deck along the coast and this will continue overnight. Expect
MVFR conditions to develop on Wednesday morning. MVFR will be more
likely along the NC coast with SC terminals approaching MVFR later
in the morning. As of right now, most models have the developing low
pressure system remaining well offshore which will bring light rain
to ILM, with only VCSH throughout the day at coastal SC terminals. A
feed of low-level marine moisture could lead to the development of
IFR conditions along the coast with low stratus the primary threat,
late Wednesday afternoon; MVFR elsewhere. Showers ending after the
end of the forecast period. Northeast winds 5-10 knots increasing
throughout the forecast period.
Extended Outlook...Likely MVFR late Wednesday through Thursday with
storm system. VFR returns Friday into weekend.
As of 900 PM Tuesday...SCA conditions to continue across all
waters. Models are in decent agreement in developing a kink in
the sfc pressure gradient where the sfc low will develop on it.
This kink will extend from 41013 northwest to the Cape Fear
region overnight into Wed. Looking at winds becoming ENE to E
north of the kink and NNW-NNE south of this kink. Wind speeds
will increase to a solid 20 to 30 kt in the vicinity of this
kink with few to occasional gusts to Gale force. Significant
seas will further build from Cape Fear northward with double
digits possible...and hold steady south of the Cape as the fetch
As of 3 PM Tuesday...Small Craft Advisory continues over all
waters for a prolonged period of 15-25 kt NE winds with gusts up
to 30 kt. This as strong high pressure anchors off to the NE
and surface low pressure develops just offshore late Wednesday.
Winds may diminish as the center of low pressure moves directly
over the local waters Wednesday night, but continued high seas
may warrant an extension to the current Small Craft Advisory end
time (midnight Wednesday night).
Offshore flow will develop as high pressure begins to
build in behind departing low on Thursday. The diminishing off
shore flow will allow seas to subside from advisory levels Thurs
morning down to 3 to 5 ft by end of the day. Gradient will
remain a bit tight, though, as high pressure builds down and
low strengthens off the coast of New England into Fri. Therefore
winds may increase again Thurs night into early Fri, with seas
slower to drop, especially in the outer waters Fri.
By the weekend, winds will lighten as high pressure migrates
slowly eastward reaching overhead by Sunday. This will produce
improving marine conditions over the weekend with seas 2 to 4 ft
on Sat and down less than 2 ft on Sunday.
NC...Coastal Flood Advisory until 11 PM EDT this evening for NCZ107.
MARINE...Small Craft Advisory until midnight EDT Wednesday night for
Gale Warning until 3 PM EDT Wednesday for AMZ250-252.
Area Forecast Discussion
National Weather Service Key West FL
940 PM EDT Tue Mar 19 2019
After a lull in the precip activity across the Keys during the
late afternoon hours, stratiform rain coverage and embedded shower
coverage has increased once again during the mid evening, although
most of the rainfall remains light at this time. Skies are cloudy
over the Keys, with temperatures mostly in the lower 70s, and
winds on land from the northeast at 15 to 20 mph. Surface analysis
indicates that a weak low pressure area is likely located near the
northwest coast of Cuba, while water vapor satellite imagery shows
one more disturbance moving eastward across the southeastern Gulf,
with a much drier airmass filling into the central Gulf behind
this feature. The 00Z Key West sounding remained very moist with
PW of 1.74 inches, which is well above the 90th percentile for
In the short term, expect mostly stratiform light to moderate
rain to continue across the Keys for the rest of the evening. An
isolated embedded heavier shower or even a thunderstorm cannot be
ruled out over the island chain, but it is more likely that any
thunderstorms will remain over the Straits and south of the Keys.
As the disturbance currently in the SE Gulf moves quickly eastward
across the Keys late tonight, shower activity should taper off
over the Keys and Gulf waters as the primary area of deep moisture
and lift shifts SE into the eastern Straits. Otherwise, windy
conditions should also taper off late tonight, and low temps
should drop only a few degrees into the upper 60s. The public
forecasts have been updated to reflect the above thinking.
A much drier pattern remains on track for the Keys beginning
Wednesday, with rain chances tapering off to slight, then none by
Thursday afternoon. Expect mostly clear, dry and seasonable
weather for Thursday through Saturday, with highs in the upper 70s
to near 80 and lows in the mid 60s to near 70. Scattered showers
may return to the area beginning Sunday and continuing into early
next week, but recent model guidance has trended drier, and later
shifts may reduce rain chances for those periods.
NE winds have gradually decreased across much of the Keys coastal
waters during the evening, but recently surged back up to 27 knots
sustained at Pulaski Shoal Light. This may be due to the low
pressure area passing to the south of the western Straits at this
time. Winds are currently running below 20 knots at most of the
other reporting sites, but short-range model guidance suggests
that winds will surge back up above 20 knots across much of the
marine area during the next several hours as the low passes to our
south. Will maintain the Small Craft Advisory for all zones with
the late evening forecast issuance. We do expect winds to begin
decreasing toward morning, and to continue dropping on Wednesday.
Large area of light to moderate stratiform rain will spread
across the terminals for the rest of this evening. Heaviest rain
with lowest cigs/vsbys will come later this evening in the 02z-
05z time frame. During that time, cigs below 010 and vsbys in the
4- 6SM range are possible, as indicated in GFS statistical
guidance. Heavier rain should then taper off to showers before
midnight. The boundary layer will remain richly moist into Wed
morning, with GFS LAMP guidance carrying MVFR cigs in the 010-020
range until 17z at EYW. Have only shaved this expectation a little
with scattering indicated at 16z (noon) in the TAFs. The HRRR
even shows cigs hovering just below 010 on a temporary basis as
late as 14z-15z on Wed morning. Expect rapid scattering and
lifting of cloud bases after about 16z to 17z.
On this date in Florida Keys weather history, in 2003, the low
temperatures at Key West (78F) and Marathon (79F) were both warmer
than the high temperatures recorded today. The high at Key West
today was 75F and at Marathon it was 77F.
The low at Marathon on March 19th, 2003 was the first of 3 days
in a row with a low temperature of 79F, tying as the warmest low
temperature ever recorded in the month of March.
GM...Small Craft Advisory for GMZ031>035-042>044-052>055-072>075.
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Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1027 PM EDT Tue Mar 19 2019
High pressure will build in from the northwest tonight. Low
pressure will develop to the south Wednesday and lift north
across the area Wednesday night. The low will lift north of the
region later Thursday pushing a cold front offshore Thursday
night. High pressure will build into the area late week and
into the weekend. Low pressure is expected to impact the region
early next week.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 1015 PM Tuesday...Area of sprinkles or light showers now
stretches from the western Albemarle Sound south and southeast
to Cape Lookout, with latest HRRR suggesting light sprinkles or
showers could persist over this area for much of tonight. Have
added slight chance PoPs for the eastern half of the CWA for
this light precipitation. Weak convection continues adjacent to
the Gulf Stream, 20-40 nmi from shore.
High pressure will continue to build south over the area tonight.
Meanwhile, low pressure is forecast to develop along a front
stalled to the southeast off the coast. As the low develops it
will push a trough of low pressure toward the NC coast late
tonight. Sky cover will continue to increase overnight and
especially for coastal sections. Heavier showers will remain
offshore tonight, then could move onshore late tonight as the
through gets closer to the coast and have continued chance/slight
chance coastal PoPs late. Temps will be 35-40 inland and 40-45
coast. Continued breezy to windy tonight, esp along the coast,
as gradient tightens between the high to the west and the
through off the coast.
.SHORT TERM /WEDNESDAY/...
As of 325 PM Tue...The trough of low pressure will move slowly
and should be along the coast late Wed. Showers will become more
numerous and penetrate further inland, especially in the
afternoon. PoPs will increase to likely most areas in the
afternoon. Precipitation amounts will be quite variable, but
could be as high as .50-1" in frequent showers which are most
likely to occur vicinity of the coast. Highs will be in the mid
to upper 50s. Continued breezy to windy in the morning, esp
along the coast, then winds should slowly diminish in the
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
As of 300 PM Tuesday...An area of low pressure will lift across
the area Wed night into Thu bringing a period of unsettled
weather and breezy conditions. High pressure will build over the
area this weekend bringing dry wx and a warming trend.
Temperatures will be near to slightly below through the week,
then warm to slightly above normal early next week. The next
system look to impact the area Mon night and Tue.
Wednesday night through Thursday night...A robust upper trough
will approach the area Wed night and this will lift surface low
pres N across the region Wed night with it lifting N of the
region later Thu. Most all mdls show decent amount of moisture
and rain spreading across the region with the sfc low Wed night
and early Thu. Have increased pops to likely inland and
categorical coast Wed night. Given low track just inland added
some thunder to imd cst/cstl wtrs Wed night. As the low lifts
to the N later Thu precip shld taper off and end from SW to NE
in the aftn. Much drier are will spread in Thu night as cold
front trailing low pushes offshore. Lows Wed night will be mild
with 40s inland to 50s beaches. As precip tapers of Thu and
skies brighten some in aftn temps expected to reach low/mid 60s.
Lows Thu night will range from lower 40s inland to mid/upr 40s
Friday through Monday...The upper trough pushes offshore Fri
with height rises through the weekend with an upper ridge and
surface high pressure becoming centered over the area Sun. The
high will drift offshore Mon with a complex system approaching
from the west. Dry conditions continue over the weekend with a
gradual warming trend early next week. Some guidance is showing
light showers developing across the area Mon and cont slight
chance PoPs. Highs expected to continue in the low to mid 60s
inland to mid 50s coast Fri and Sat. Temps expected to warm into
the upper 60s to lower 70s inland to low to mid 60s coast Sun.
Some mid 70s poss Mon inland with SW flow on backside of high.
Mon night and Tue...Next short wave and low pres system will
impact the area this period. Long range mdls look quite wet and
windy with this system but given timing and track uncertainty
this far out will keep pops in chc range.
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Short Term /through Wednesday/...
As of 725 PM Tuesday...Expecting VFR conditions through Wed
morning as high pressure prevails across the area. Some mid
level broken clouds currently for TAF sites, though should
remain VFR overnight. By Wed afternoon a trough of low pressure
will form along the coast resulting in scattered to numerous
showers with brief sub-VFR conditions possible. Late Wed
ceilings are forecast to become sub VFR and showers will become
Long Term /Wednesday night through Sunday/...
As of 300 PM Tuesday...Good cvrg of rain expected Wed night as
low pres lift N across area...bouts of sub VFR a good bet.
Precip will taper off from S to N Thu as low lifts N of region
and shld grad see VFR return. VFR expected Fri through Sun as
high pres builds across with dry air over region.
Short Term /through Wed/...
As of 1025 PM Tue...Latest surface and buoy data indicate NE
winds 20-30 kt with seas 5-8 ft across the waters. Strong winds
and elevated seas will continue Wednesday. N/NE winds 20-30 kt
with gusts 35-40 kt south of Oregon Inlet where Gale Warnings
are in effect. These winds will continue through early Wed in
response to the gradient between high pressure to the north and
low pressure to the south. Seas will build to 7-10 ft tonight.
The winds are forecast to become E/SE Wed and decrease to 15-25
kt as a trough of low pressure moves along the coast. Seas
however, will remain 7-10 ft as the flow becomes SE and begins
to increase again late.
Long Term /Wednesday night through Sunday/...
As of 300 PM Tuesday...Low pres will lift N inland from cst Wed
night then cont to move N of region later Thu. Expect gusty E to
SE winds ahead of low Wed night that will grad shift to WNW and
remain gusty later Thu. Cold advection and decent grdnt will
keep NW winds gusty Thu night into Fri. NW winds increase a bit
later Fri night and early Sat as secondary surge of cold air
crosses. Winds diminish and become light Sat night into Sun as
high pres builds in.
Seas will be in the 6 to 10 ft range Wed night and slowly
subside to 5 to 8 feet Thu. Seas will be mainly in the 4 to 6
foot range Fri into Sat with gusty offshore flow. Seas will
subside to 2 to 3 feet later Sat night and Sunday.
As of 3 PM Tue...Persistent gusty NE flow combined with high
astronomical tides could lead to minor water level rises for
areas adjacent to the Southern Pamlico Sound through
tonight...from Downeast Carteret County over to areas along the
Neuse River and adj. creeks. Rises not expected to exceed 0.5 ft
above ground or 1 ft above normal at this time.
Gusty SE flow Wed night will lead to higher than normal water
levels along the south facing beaches and may also need High
Surf Advisory as waves in surf zone approach 8 ft.
MARINE...Small Craft Advisory until 2 PM EDT Wednesday for AMZ130-131-
Gale Warning until 8 AM EDT Wednesday for AMZ152-154-156-158.
Small Craft Advisory until 6 PM EDT Friday for AMZ150.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
643 PM PDT Tue Mar 19 2019
.SYNOPSIS...A cooling trend will begin today as cloud cover
increases over the region ahead of an approaching weather system.
Rain showers will develop over the region tonight into Wednesday
with an unsettled pattern likely to continue through late week.
While dry conditions are possible this weekend, unsettled weather
will return heading into next week.
.DISCUSSION...as of 02:40 PM PDT Tuesday...A negatively tilted
trough continues to slowly approach California from the west
this afternoon. This storm system is aligned nearly parallel with
the coastline from Point Arena through Santa Barbara and has
already brought increased cloud cover, cooler temperatures, and
higher humidities to the region thus far today.
Southerly winds will progressively strengthen ahead of the cold
front through the remainder of the day, becoming gusty (peak
gusts up to 40-50mph in the windiest spots) along the coast and
over the higher terrain with breezy winds elsewhere.
Latest KMUX radar imagery is detecting light reflectivity returns
ahead of the leading edge of a cold frontal boundary approximately
60 miles off of the coast. Despite the close proximity to the
area most models delay the onset of precipitation moving inland
until much later this evening, owing to the negative tilt and
sluggish speed of the parent trough. The latest model output has
decreased the overall precipitation intensity and coverage versus
previous runs. Storm total precipitation will range from 1.25-2.25"
for the higher terrain of the Santa Cruz and Big Sur mountains
while urban areas will generally range from 1/5" to 1/3", with
rain shadowed areas on the lower end of the spectrum. HRRR model
output confines precipitation mostly in broken bands and scattered
showers wrapped closely on the eastern flank of upper low as it
lifts northeastward across the region. Previous model runs showed
somewhat more organization and strength than the current runs and
have reduced overall QPF as a result.
Models generally agree that precipitation should begin to spread
inland between 10pm and midnight tonight, however, a few precursor
showers could arrive in time for this evenings outbound commute.
Rain intensity and coverage should scale upwards after midnight as
the upper low shifts inland and lifts northeastward over the San
Francisco Bay Area. Isolated thunderstorms will be possible
overnight tonight through Wednesday morning due to an increasingly
unstable environment advecting into the region. The overall
weaker model output from the latest runs may increase the
potential for thunderstorms Wednesday as a result increased cloud
breaks leading to more surface heating and further destabilization
of the atmosphere.
A secondary vorticity pulse on the rear flank of the broader
trough will descend into the local area later Wednesday into
Wednesday night and extend the possibility of a few lingering
showers potentially into early Thursday. Confidence is relatively
low regarding how this second disturbance will interact with the
initial disturbance with some models introducing an increased
chance of showers over the higher terrain into Thursday morning.
A transitory high pressure ridge will develop by midday Thursday
allowing for a brief warming/drying trend, however, another storm
system is set to descend into the region from the Gulf of Alaska
by Friday morning. Fridays storm system will move from north to
south and bring the bulk of any precipitation to the North Bay.
Precipitation along the North Bay coastal range could approach
1.00" while the North Bay valleys pick up 1/2 to 2/3". Much less
precipitation is expected south of the Golden Gate, with 1/4 to
1/3" in the immediate SF Bay Shoreline, and progressively less
Drier weather will prevail through most of the weekend with a
slight warming trend into Sunday but a third storm system will
begin to advance on the region early next week. Forecast models
and ensemble members continue to pepper later Monday through early
Wednesday as wet time periods, however, there is still a bit too
much noise to pin down exactly when, where, and how much to
.AVIATION...As of 6:43 PM PDT Tuesday...Increasingly strong and
gusty winds through the evening, low level wind shear developing
nearest the coast with some overlap into the South Bay, possibly
extending to the East Bay and North Bay later this evening.
Showers arriving later in the evening into Wednesday. Terminals
reporting VFR thus far.
An amplifying and negatively tilted 500 mb height trough is approx
200 miles southwest of Monterey county and moving north and will
sweep over the area through the evening and overnight. Showers on
Wednesday. NAM model shows fairly rapid cold air advection through
06z, near 7 Celsius cooling at 925 mb and 850 mb levels and
thermal troughing embedded with the 500 mb height trough indicating
this trough has a fair amount of dynamics and lift with it. Expect
rapidly changing weather conditions at least through the evening.
Clouds looking convective southwest of SLO county, but not seeing
lighting yet; echo tops near 20 thousand feet. There`s a slight
chance of thunderstorms mainly late tonight into Wednesday morning.
Vicinity of KSFO...Increasingly strong and gusty winds through the
evening. Wind flow tending to downslope, dry out any chance of
showers in nearest term. Low level wind shear developing by mid to
late evening and lasting into early Wednesday morning. Showers
arrive overnight. VFR decreasing to MVFR ceilings late tonight
into Wednesday morning. VFR Wednesday with a few showers.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR, increasing winds. Wind flow is
downsloping and drying in lee of the Santa Lucia mountains drying
out any chance of showers in nearest term. Expect rapidly changing
weather through the evening including low level wind shear through
the evening into early Wednesday morning. Showers expected to
arrive overnight into Wednesday. MVFR ceilings in showers. VFR
Wednesday and lingering showers.
.MARINE...as of 5:18 PM PDT Tuesday...Southerly winds will continue
tonight ahead of an approaching low pressure system and cold front
moving in from the west. Winds will increase overnight and tomorrow
before winds veer to the west to northwest later tomorrow. A long
period west swell will continue into this evening increasing
shoaling on bars and harbor entrances. An additional long period
west to northwest swell will arrive towards the end of the week.
.Tngt...SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...SF Bay from 3 AM
SCA...Pt Arena to Pigeon Pt 10-60 nm from 3 AM
SCA...Pt Arena to Pt Reyes 0-10 nm from 3 AM
SCA...Rough Bar Advisory for SF Bar from 9 PM
PUBLIC FORECAST: DRP
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...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Wednesday night)
Issued at 340 PM CDT Tue Mar 19 2019
As of 20Z Tuesday afternoon a midlevel shortwave trough was centered
across the NE panhandle with an attendant surface trough extending
from near Wichita, KS to near Hiawatha, KS. A band of post-frontal
rain shower activity continues to progress eastward across the
forecast area. The primary concern through the remainder of the
short-term period is enhanced rainfall rates due to shallow
convection that could lead to brief heavy rainfall. RAP and HRRR
forecast soundings continue to suggest upwards of a 50 J/kg of
MLCAPE may reside ahead of the boundary, which may briefly increase
rainfall rates. Generally additional rainfall amounts of 0.10" to
0.50" can be anticipated with lowest amounts south of I-70 and the
higher amounts north of I-70.
Temperatures have rapidly warmed southeast of the surface front with
deep mixing of the boundary layer in upwards of 700 mb. This has
resulted in surface temperatures surging into the 60s, especially
along and southeast of the KS turnpike. In addition, southwest winds
have gusted upwards of 30-35 MPH in portions of east-central KS,
where boundary layer mixing has been maximized. Some fire danger
concerns will continue through the remainder of the afternoon across
east-central KS given the gusty winds and relative humidity values
in the 20 to 30 percent range. Rich soil moisture and decreased fuel
load due to flattening of grasses from multiple winter snow events
should mitigate fire concerns through the short term period. Post-
frontal temperatures have generally decreased into the 40s. This
trend should continue into the evening with temperatures rapidly
decreasing behind the cold front.
Transitioning into tonight, the main midlevel shortwave and
attendant surface trough will progress east of the forecast area
ending precipitation from west to east. All precipitation is
expected to exit the area by 09Z. A secondary midlevel shortwave
trough is progged to traverse portions of the Great Lakes region
through the day Wednesday, shunting a secondary weak surface
boundary through the CWA late Wednesday afternoon into the evening.
Ahead of the front winds will veer to predominately a west direction
through the lowest 5kft of the atmosphere. With the downslope
component combined with deep boundary layer mixing, upwards of 850
mb, will yield mild temperatures in the 50s to near 60 area-wide.
Limited moisture should yield a dry frontal passage as winds veer to
the north Wednesday night. Surface high will build into the area
Wednesday night as low temperatures reach the low to middle 30s.
.LONG TERM...(Thursday through Tuesday)
Issued at 340 PM CDT Tue Mar 19 2019
A highly amplified midlevel ridge axis will overspread the central
US Thursday into Friday, ahead of a midlevel low across the western
US. Temperatures Thursday and Friday are progged to reach the upper
50s and lower 60s. The midlevel low will become cutoff by weeks-end
and begin to fragment into multiple shortwave troughs. Precipitation
chances look to increase late Friday into Saturday as the initial
shortwave traverses the Plains. Rain chances will persist into early
next week as additional shortwave troughs traverse the Plains. Lapse
rate profiles continue to show a weak signal given the weak nature
of the midlevel trough. Temperatures look to remain quite mild with
highs in the 50s and 60s into next week.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 630 PM CDT Tue Mar 19 2019
Band of showers will bring some reduced visibilities to TOP and
FOE over the next few hours, with MVFR cigs expected to move into
all terminals by 03Z. Based on MYZ observations, will include
some IFR cigs at MHK for a few hours and could see these
conditions be more prevalent through much of the night. VFR
conditions should return by 17Z with dry air on west winds
Area Forecast Discussion
National Weather Service Las Vegas NV
830 PM PDT Tue Mar 19 2019
.SYNOPSIS...Cloud cover is expected to increase through tonight
and precipitation chances will begin to increase from west to
east this evening through overnight tonight. Unsettled weather
will continue through Thursday with valley showers and mountain
snow. Expect a brief break on Friday before another weather system
moves into the region by Saturday.
.UPDATE...Scattered showers ahead of negatively
tilted trough over northwest San Bernardino County and southern Inyo
County will continue to develop and drift northward overnight. So
far, rain buckets across the southern Sierra reporting less than a
tenth of an inch of rain over the past 3 hours.
HRRR and HREF simulations quite similar tomorrow depicting a more
widespread band of precipitation across Lincoln County, southwest
Utah and northern Mohave County tomorrow afternoon. A more broken
line develops across Nye, Clark and northeast San Bernardino
Counties late afternoon and evening.
Updated the POPs based on the hi-res model output the rest of
tonight which keeps the highest POPs across Inyo County. No other
.DISCUSSION...Today through Monday.
The latest satellite imagery shows scattered high clouds beginning
to fill in across the region with some cumulus developing mainly
near higher terrain this afternoon. These trends will continue
through this evening with cloud cover increasing as an approaching
negatively tilted trough continues to dig into our region. Moisture
is fairly limited with this system but isolated to scattered showers
will begin to increase later this evening across Inyo County. As the
trough digs further into SoCal tomorrow, upper level difluence and
daytime heating will provide enough forcing and lift to initiate
showers and isolated thunderstorms across the Mojave Desert. The low
will eventually cut off overhead on Thursday before lifting off to
the northeast early Friday continuing precip. chances through that
time. Decent instability will be in place on Thursday across the
region allowing for more scattered thunderstorm chances mainly
across southern NV and northwest AZ. With marginal moisture and dry
low levels, storm totals are not expected to be impactful. Snow
levels will start off around 7500-7000 feet and begin to drop
overnight Wednesday to around 5500 feet. Again, with marginal
moisture, 48+ hour snow totals are 7-10 inches above 7000 feet along
the eastern Sierra, 4-6 inches in Lee Canyon and only 1-2 inches in
Kyle Canyon. Low amounts over a 48+ hour period should limit impacts
and no winter weather products are expected. Besides
precip./thunderstorm chances, no other impacts are expected with the
mid-week weather system. Winds will be breezy from the south-
southeast through this evening across much of the region. Some
breezy to gusty southeast winds will be possible across areas
north and east of Clark County tomorrow afternoon as the trough
digs into southern NV and pressure gradients increase across those
areas. Of course with any thunderstorm activity, winds may be
variable and gusty.
By Friday, a shortwave ridge will briefly be overhead in the
afternoon pushing any lingering moisture northeast. The break in
clouds and storm chances will be very brief though as another trough
is progged to dig into the Great Basin region overnight Friday
into Saturday. This next system will be fast moving and should
keep precip chances confined to south-central NV. Another ridge
will move overhead Sunday bringing mostly sunny skies through
.AVIATION...For McCarran...Light easterly winds are expected at the
terminal through the rest of the afternoon and evening before
turning back to the southeast overnight remaining below 10kts. An
increase in cloud cover is expected gradually throughout the day aoa
10kft. An incoming system tomorrow should further increase cloud
cover and shift winds to the south in the afternoon. Could become
gusty as well.
For the rest of southern Nevada, northwest Arizona and southeast
California...An incoming storm system over the next 24 hours will
first impact KBIH with gusty south winds and an increase in cloud
cover and -SHRA by late this evening. KDAG will also see a response
in winds, initially being out of the southeast and shifting to
southwest late this afternoon. Minimal impacts expected at
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
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