Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/14/19
AREA FORECAST DISCUSSION
National Weather Service Cleveland OH
1052 PM EDT Sat Apr 13 2019
Low pressure over the southern United States will move northeast
overnight. This low will move over Ohio on Sunday and extend a
warm front over the area by Sunday afternoon. The low will
depart to the northeast on Sunday night and extend a cold front
over the area by Monday morning. High pressure moving through
the southeastern United States on Monday night will ridge into
the eastern Great Lakes for Tuesday. Low pressure over the
Central Plains on Tuesday night will extend a warm front over
the area before moving east on Wednesday.
.NEAR TERM /THROUGH SUNDAY NIGHT/...
Main update to the forecast this evening is to slow down the
arrival of precip after midnight. Based the forecast update on
the latest trends with radar and hi-res guidance, which holds
off precip until generally after 06-07Z across the forecast
area. Otherwise, just minor updates to temperature trends
Looking at Sunday`s severe weather threat, the latest HRRR is
trending stronger/westward with the surface low, bringing the
warm front farther north through the area, and putting the area
squarely in the warm sector. This trend would support an
increased severe weather threat tomorrow afternoon for the
central and eastern part of the forecast area. Will continue to
monitor the latest trends in the guidance overnight and adjust
the forecast accordingly.
High pressure over the Upper Midwest extends east over the Great
Lakes region this afternoon and is keeping the area dry. The
only nuisance this evening will be some cirrus advecting in from
the southwest. Low pressure over the southern CONUS will move
northeast tonight and reach the lower Ohio Valley by daybreak on
Sunday. This low will bring rain to the region on Sunday into
Sunday night as the low moves northeast through the state of
Ohio. With the low bisecting the state, this low will extend a
warm front north into north central and northeast Ohio and
temperatures will surge into the mid to upper 60s. The warm
sector will be the focus for thunderstorms and perhaps some
strong to severe thunderstorms as this is where the best
instability will reside, along with the warm frontal boundary
that may be a spot where thunderstorms may initiate and persist.
With this, have thunder in the forecast limited to the warm
sector or mostly counties along and east of I-71. On the back
side of the low, temperatures will remain cold with temperatures
in the 40s and 50s and rain will be much more stratiform in
nature. As the low departs the region, rain chances decrease
from west to east, but rain will linger from Sunday night into
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The surface low pressure system will be pulling away from the region
on Monday. The upper level trough will be right over the area Monday
and also moving eastward. We can expect mostly cloudy skies and
breezy conditions with a few scattered showers on Monday. Weak high
pressure will move over the area Monday night with lighter winds.
Light southerly winds will return on Tuesday. A weak warm front
lifting back northward may bring a few showers on Tuesday,
especially closer to the lake. It will be milder on Tuesday and
warmer on Wednesday.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
We will be watching for another strong storm system to develop in
the central U.S. by the middle of the week. This weather system will
be another dynamic system with a strong upper level through and a
strong surface low developing. The system will have a good source of
moisture and wind shear. Late Thursday afternoon into Thursday night
will be the timeframe we will be watching for the possibility for
strong to severe convection. The Storm Prediction Center already has
a portion of the region in a day 6 outlook for this potential.
Temperatures will be warm and Spring-like for the middle and end of
.AVIATION /00Z Sunday THROUGH Thursday/...
Low pressure will track northeast across Ohio on Sunday, with
rain ahead of the system moving into the terminals during the
first half of the period. VFR conditions will deteriorate to
MVFR and potential IFR after 12Z as the low moves into southwest
Ohio. As the low tracks northeast across the local area Sunday
afternoon, a line of thunderstorms is expected to develop,
possibly impacting KMFD to KCLE and terminals east, mainly from
21Z through the end of the period. Winds will becoming north to
northeast ahead of the low overnight, with a shift to southerly
winds along/south of the low track tomorrow afternoon with
increasing gusts to 20-25 kts. Winds will become westerly behind
the low towards the end of the period.
OUTLOOK...Non-VFR likely into Monday and possible again Monday
night into Wednesday.
A low pressure system will be approaching the region from the
southwest tonight into Sunday morning. Light winds this evening
will shift to northeasterly. Winds will increase 15 to 25 knots
on Sunday. Waves on the lake will also build. The water level on
the lake is already running high at about 20 inches above
normal. Northeast flow on Sunday will likely cause water levels
to rise on the western end of the lake. A coastal flood watch
has been issued for western shoreline areas of the lake for
Sunday. A small craft advisory has also been issued for
increased winds and waves. An additional small craft advisory
will likely be needed Sunday night into Monday for gusty west to
northwest winds behind the passage of the cold front. There
will northwest winds 15 to 25 knots on Monday as the surface low
moves away from the area. Weak high pressure will move over the
region Monday night with lighter winds. Winds will become
southerly again for the middle and end of next week. Another
strong area of low pressure will impact the region late next
week with gusty winds.
OH...Lakeshore Flood Watch from 8 AM EDT Sunday through Sunday
afternoon for OHZ003-007>009.
MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Sunday for
Area Forecast Discussion
National Weather Service Grand Forks ND
705 PM CDT Sat Apr 13 2019
Issued at 702 PM CDT Sat Apr 13 2019
Fcst in good shape. Surface high pressure ridge axis roughly
Roseau to Fargo and slowly moving east. HRRR model indicates best
fog chances near or just east of this ridge axis later tonight
which will be Bemidji-Fergus Falls region into eastern SD and
farther south into SW MN. I will leave fog mention other areas per
current fcst but chances appear more spotty for areas west of the
sfc ridge over the central and northern RRV and far NW MN and NE
.SHORT TERM...(This afternoon through Monday)
Issued at 336 PM CDT Sat Apr 13 2019
Ridge aloft and surface high pressure keeping quiet conditions in
place with moderating temps aloft and sunny skies supporting some
locations as warm as 50 in our northwest this afternoon. All
locations at or above freezing, though deeper snow pack in our south
has limited warm up. Generally clear skies, calm winds, and
lingering low level moisture (from daytime melting) will support fog
development, though RAP/HRRR are not widespread in fog signal.
NAM/ARW/NMM showing much stronger signal for dense fog. I kept
patchy fog across our CWA with "areas" coverage where strongest
overlap/consensus with shorter range guidance shows it. This will be
the main concern for overnight/morning period.
Sunday-Monday: After any fog lifts Sunday morning, dry/quiet
expected through Sunday afternoon, with temps in line with today
(40s maybe an isolated 50). Negatively tilted shortwave trough
tracks along International Border Sunday night and east of our area
by Monday morning. Strong forcing (WAA ahead of this system followed
by strong 850-700MB frontogenesis) is shown to track across our CWA.
Duration of forcing/moisture advection is quick, but this should
support increasing precip chances (especially north). Lapse rates
are favorable for possible more intense showers to develop, but due
to duration, even convective allowing guidance is only showing high
end QPF generally around 0.25". Current potential is there for a
wintry mix of rain/snow (some sleet) and light snow accumulations
before precip ends Monday monitoring. Westerly flow and drier
air/clearing skies follows this system, so milder highs should
arrive Monday for most of our area (50s for more locations).
.LONG TERM...(Tuesday through Saturday)
Issued at 336 PM CDT Sat Apr 13 2019
Model consensus favors near normal to slightly above normal temps,
but there is more uncertainty in the middle of the week for temps
and precipitation chances. Another strong system may develop into
the Central US. Main track/forcing/QPF axis from latest ECMWF/GFS is
further south. Late runs do show a possible 700MB deformation axis
extending northward from this system into our CWA which could bring a
period of higher precipitation into our area. Right now rain is
favored based on current timing, but soundings at least support
potential for more in the way of snow than rain. Evolution of this
system, track, and timing of CAA all will play a role in impacts over
our area, and confidence is low as models have varied on these
details. This will need to be monitored. Another quick moving
(weaker) system may bring precip chances by next weekend, but
impacts would be lower and at this range it isn`t as much of a
focus for concern.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 702 PM CDT Sat Apr 13 2019
Radiational ground fog is the issue later tonight/Sun AM. These
are always tough to forecast ahead of time in terms of exact
location and impacts at airports. It appears best chances would be
Bemidji to Fargo and south/east of this area. Kept some light fog
BJI, FAR, TVF overnight kept vsbys in the TAF in MVFR range.
Issued at 336 PM CDT Sat Apr 13 2019
Regionally, recent snowfall across is expected to begin melting in
the coming days as temperatures climb and remain above freezing.
This will drive either an increase in water levels or will slow down
water level decline at most points along the mainstem Red River.
The Red River at Fargo will see a secondary rise around mid-week as
snowmelt works it`s way into the channel. Other notable rises could
occur along the South Buffalo and Buffalo at Sabin, Hawley, and
Water levels on the Snake River upstream of Warren have continued
falling over the past 24 hours and have fallen below action stage.
Slight increases in the coming days are possible as snow melt runs
off into the river, but no rise to Minor flood stage is expected at
At Hallock, we will see the decrease in water level begin to level
off as increased melting and runoff are expected to cause a
secondary rise in river levels.
Areal and river point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.
Area Forecast Discussion
National Weather Service Huntsville AL
925 PM CDT Sat Apr 13 2019
.NEAR TERM...(Rest of tonight)
Issued at 925 PM CDT Sat Apr 13 2019
After coordination with SPC, have added a few more counties up to the
TN border in the Tornado Watch until 08Z. The warm front continues to
make progress northward with temperatures warming into the upper 60s
to around 70, with dew points in the lower to middle 60s. Further
south, southeast inflow continues with temps in the m70s and dew
points in the m60s nosing into west central AL. This air will feed
the incoming QLCS(s) in MS. The HRRR suggests that these QLCS will
maintain a threat of damaging winds and tornadoes feeding off very
high 1km SRH values of 400+ and MLCAPEs of ~500+ just south of the
warm front. The threat may go beyond 08Z in our northeast AL
.SHORT TERM...(Sunday through Sunday night)
Issued at 407 PM CDT Sat Apr 13 2019
As previously mentioned, the threat for severe weather will persist
into Sunday morning. The main line is expected to exit the forecast
area around 15Z and some drier air will filter in. There will be a
break in activity before another round of storms is expected with the
arrival of the cold front and the passage of the upper-level system.
Instability will be lower but lapse rates will improve and 0-6km
shear will be approaching 90kts. With winds more unidirectional than
the overnight hours, the main threat will be damaging winds and hail
for the afternoon hours. Locations east of I-65 will have the higher
chances to see severe weather during this time. Precip will come to
an end Sunday night as the system lifts NE. Daytime highs could reach
the lower 70s and fall into the upper 30s/lower 40s behind the cold
.LONG TERM...(Monday through Friday)
Issued at 407 PM CDT Sat Apr 13 2019
The extended period will begin with dry northwest flow aloft in the
wake of a trough lifting northeastward off the mid-Atlantic coast.
Although any lingering postfrontal cloud cover should dissipate
rather quickly in the morning, modest low-level CAA in the wake of a
frontal passage Sunday afternoon will provide cooler max temps in the
mid 60s on Monday and min temps in the mid 40s Monday night, as
conditions will be favorable for radiational cooling. A warming trend
is expected to begin on Tuesday, as a low-amplitude mid-level ridge
translating across the region will provide mostly sunny skies
concurrent with the return of southerly flow in the boundary layer.
We expect highs to reach the m-u 70s both Tuesday/Wednesday, with
lows Wednesday morning only falling into the l-m 50s in a regime of
increasing low-level moisture.
By the middle of next week, our attention will focus on an
amplifying 500-mb longwave trough, which extended range models
suggest will be migrating slowly eastward across the central Plains
on Wednesday. At least a couple of weak disturbances ejecting
northeastward in strengthening southwest flow aloft will cross the TN
Valley from Wednesday-Wednesday night, perhaps bringing a few
showers and thunderstorms to the northwestern half of the area.
However, coverage of showers and thunderstorms is expected to
increase across the same area early Thursday morning, as deeper
moisture begins to return northward in advance of the approaching
Global models indicate that further deepening/amplification of the
broad longwave trough can be expected on Thursday and Thursday night,
as the system translates slowly eastward across the central Plains
and into the MS Valley, with the intensification process expected to
peak sometime early Friday morning. At the surface, a low initially
across IA will lift east-northeastward into the Great Lakes, with a
Pacific cold front extending southward from the low expected to push
eastward across the local area Thursday afternoon/evening. Latest
guidance suggests that strong forcing for ascent attendant to the
longwave trough will result in upscale growth of a QLCS along the
Pacific cold front, and based on a favorable combination of
atmoshperic lift, instability and deep-layer shear we strongly
suspect that this will produce another severe thunderstorm event for
the TN Valley. Low-level flow will veer to southwest by early Friday
morning, but should result in limited advection of dry air, and with
the axis of the longwave trough remaining to the west of the region,
we anticipate a continuation of clouds and perhaps some showers on
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 549 PM CDT Sat Apr 13 2019
VFR flight weather conditions will continue through around 06Z at
KMSL and 08Z at KHSV. However, southeast surface winds will abruptly
increase to 15-18kt with gusts around 28kt, with LLWS developing.
Gusts should reach 30kt by 06-08Z with lower ceilings of 015-025agl
expected (MVFR). A few showers or thunderstorms cannot be ruled out
this evening, but the main line of thunderstorms arrives between
06-08Z at KMSL and 08-10Z at KHSV. Strong wind gusts will be possible
with the line of thunderstorms. After the thunderstorms and showers
end by 11-12Z, expect a wind shift to the southwest with continued
gustiness up to 30-32kt.
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AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1055 PM EDT Sat Apr 13 2019
Issued at 1055 PM EDT SAT APR 13 2019
The latest model runs show the progression of the morning line of
showers through eastern Kentucky to be slightly slower than was
originally forecast. Looking downstream at current radar, these
trends would agree. Also, there has been a downward trend in the
strength of these showers. This is particularly true in the latest
HRRR run, where an organized line of showers that was present is
now more of a broken line. Therefore, have adjusted PoPs into the
early morning hours to account for these trends. Also, with
increasing cloud cover from the southwest late this evening,
expecting the minimum temperature to occur before midnight
tonight. Thus, have also adjusted minimum temperatures and the
diurnal curve for the overnight. A new ZFP was sent to capture
these changes. Updates have also been sent to the web and to NDFD.
UPDATE Issued at 905 PM EDT SAT APR 13 2019
Monitoring as precipitation has overspread into much of western
and central Kentucky this evening. Some light, isolated showers
continue over the Cumberland Basin region as well according to
current radar. Hi-Res models show that a line of heavier showers
will advance towards eastern Kentucky after dawn tomorrow morning.
PoPs during this time are consistent with the Hi-Res models, so
only needed to make minor adjustments to late evening PoPs based
on current trends. Also ingested current observations for
temperature and winds and blended them into the forecast.
Temperatures are generally in the lower 60s at present across the
area. An updated ZFP was not needed at this time. Updates have
been sent to NDFD and to the web.
UPDATE Issued at 550 PM EDT SAT APR 13 2019
Adjusted PoPs into the evening based on the latest radar trends
that show some light precipitation moving into the Cumberland
Basin. No other significant changes were needed beyond this, other
than to ingest and blend the latest observations for
temperatures, wind, and sky cover. Current temperatures are in the
upper 60s to low 70s late this afternoon. Sent a new ZFP to
include PoP updates for the evening. Updates have been sent to
NDFD and to the web.
.SHORT TERM...(This evening through Sunday night)
Issued at 354 PM EDT SAT APR 13 2019
We are continuing to monitor the potential for strong winds and
severe storm potential on Sunday. Still a bit of uncertainty on
the extend of severe weather on Sunday as there are lots of
concerns and potential limitations which will be discussed below.
The confidence is a bit higher on the potential for large scale
wind gusts reaching or exceeding 40 mph.
Presently, s potent vort max is ejecting out of a base of a mid
level trough in the southern plains leading to a developing low
pressure system and a threat of severe storms over the lower
Mississippi river valley. This will be the system we will be
watching for tomorrow. To the northeast of this developing system,
a baroclinic zone is oriented northeast to southwest across
eastern Kentucky, providing a nice spread in dewpoints across the
area. Presently dewpoints range from the mid 30s in the north to
the mid 50s in the south. Cloud cover has limited the temperature
spread from north to south. This boundary will jump to the north
tonight as the low level jet strengthens as the deepening area of
low pressure tracks into far western Kentucky. With the jet
strengthening overnight, winds above 3000 feet in southeast
Kentucky may start to get a bit gusty. With some uncertainty with
how low the inversion will be tonight, opted to not go with a wind
advisory for these areas through tonight, but evening and
overnight shifts may need to start the advisory earlier if the
inversion ends up below the ridgetops. Moisture transport and jet
dynamics will lead to increasing rain chances for our western
areas by dawn. This activity will be fighting the downsloping
flow, but should be enough to overcome this across our western
zones, so have gone with categorical pops in the west by dawn.
Tomorrow, showers and embedded thunderstorms will continue to
spread east during the morning hours but gradually weaken as they
run ahead of the weakening jet and lack of better upper level
support. Thus, pops will have a diminishing trend during the
morning hours with a a period of lower pops for the middle of the
day. South wind will continue to ramp up tomorrow with the BUFKIT
momentum transfer showing wind gusts potential in the 40 to 45 mph
range areawide. MAV/MET numbers are also some of the highest we
have seen with the MAV at LOZ showing 25 knots. Given the high
wind potential for tomorrow, have opted for a wind advisory for
the entire forecast area.
Now addressing the severe threat. Winds will likely stay almost
due south through the day and never really switch to a southwest
direction. Thus, current thinking is that dewpoints could be
overdone on the models and readings near 60 may not be reachable.
Given instability was already a question mark, put lower dewpoints
on the table, and you will get even less instability. Thus, will
there be enough surface moisture advection to overcome the
downslope potential, especially with the strong flow expected off
the terrain? Certainly going to go lower with the dewpoints than
the model blends would entertain. The better chance for higher
dewpoints could be across our Bluegrass region where they may be
less impacted from the downsloping flow. The other aspect to deal
with tomorrow is cloud cover and potential lack of
clearing/warming. If we cannot clear, it may be hard for us to
overcome the expected lower dewpoints and generate much
instability at all. Finally, the other aspect is that the shear is
so impressive with 0-6km shear values in the 80-90 knot range.
Thus, updraft potential may be limited as they get toppled with
the strong shear. However, if any storm organization can take
place, it won`t take much to generate widespread damaging winds.
Thus, this is a precarious situation as we will be walking a fine
line. The 12z HREF does show some weak probabilities for some
updraft helicity over eastern Kentucky, and does support the
better threat across the Bluegrass region. The area remains in an
enhanced risk for severe storms, and at this point cannot
completely argue against it, but as mentioned above, there are
many aspects to this event that could yield fewer severe storms.
At this point, damaging winds will be the primary hazard given the
tremendous unidirectional shear in place with any convection
likely developing into linear bow segments.
By Sunday night, cold advection will kick into full gear with
some wrap around moisture spreading into the coal fields. This
will yield scattered rain showers or drizzle through much of the
night. A few snowflakes cannot be completely ruled out by dawn
Monday on some of the highest ridgetops along the Virginia border.
Lows will fall back into the 30s for most locations.
.LONG TERM...(Monday through Saturday)
Issued at 354 PM EDT SAT APR 13 2019
The 500 mb trough axis will have moved east of the area at the start
of the period with rising heights expected from the Southeast into
the Lower OH Valley region. Further height rises are anticipated into
Tue night. Meanwhile at the sfc, the area of low pressure and cold
front that will bring convection in the near will move further to
the north and east with sfc high pressure building into the
Commonwealth from the Gulf States. By Tuesday the sfc high is
expected to be centered along the coast of the Carolinas before
shifting into the Atlantic by Tuesday night. Further west,
meanwhile, a mid and upper level trough should move onshore of the
west coast of the Conus from late Monday into Monday night and then
progress east across the Rockies through Tuesday night and then
emerging into the Plains at midweek, when a sfc low will
develop/deepen in the Central Plains.
This pattern will bring drier, but initially colder weather to East
KY. Temperatures should not climb out of the mid 50s across much of
the area on Monday. Clearing skies under the influence of ridging on
Monday night and dewpoints in the low to mid 30s support some mid
and upper 30s for sheltered southeastern valleys, when patchy frost
will be a possibility. Tuesday and Wednesday should be considerably
milder as the sfc high moves further east and the region gets into a
return flow of initially warmer and eventually more moist air.
Temperatures should climb well into the 70s on Tuesday and at least
the upper 70s on Wednesday.
From late Wed into Wed night, the shortwave trough is expected to
close off to an upper low over the NE/KS vicinity and meander toward
the MS Valley by Thu night and Fri. Uncertainty remains in the
timing and track of this upper low with quite a bit of variability
from run to run and model to model. The model consensus is for the
upper low/trough to move east of the MS River by the end of the
period. The sfc low should track into the mid MS Valley by early on
Thu and into the Great Lakes Thu night and Friday and Ontario and
Quebec late in the period. The trailing cold front should cross the
Commonwealth by late Thu night to early on Friday. Under the
increasing influence of the trough/upper low, unsettled weather will
return with the best chances for showers and some thunderstorms
nearer to the cold front itself which at this point appears to cross
the region Thu night to early on Friday. Wind fields may be
sufficiently strong and potentially some limited instability to
coincide such that storms along or near that front could produce
gusty winds. However, the timing generally expected to be at night
or possibly early on Friday morning should be a limiting factor. The
evolution of this system will continue to be monitored in the coming
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 805 PM EDT SAT APR 13 2019
A low pressure system will approach eastern Kentucky later
tonight. This will bring rain showers and the potential for some
thunderstorms overnight tonight and into tomorrow morning.
Confidence is low if any early morning storms would affect the TAF
sites, so did not include thunder for the morning at this time. A
second wave of showers and thunderstorms will then affect the
region in the afternoon. This will be the period with the greatest
potential for strong to severe thunderstorms and thus, have
included the mention of thunder for all TAF sites. Accompanying
the heavier showers and storms will be reduced visibilities. Lower
ceilings to MVFR are also expected tomorrow afternoon as the
second wave of showers and storms moves through. The other concern
for the period will be LLWS overnight tonight and then strong
winds through the afternoon tomorrow. Easterly winds will shift to
be southwesterly and increase to be between 15 and 20 knots
tomorrow afternoon. Wind gusts between 30 and 40 knots are also
likely during this time, with locally higher gusts possible in the
higher terrain of southeastern Kentucky.
Wind Advisory from noon to 8 PM EDT Sunday for KYZ044-050>052-
Wind Advisory from 8 AM to 8 PM EDT Sunday for KYZ087-088-118.
Area Forecast Discussion
National Weather Service Key West FL
1042 PM EDT Sat Apr 13 2019
There are a lot of similarities between this evening and the
previous 2 evenings. Have been watching clouds above 5,000 feet
move north from Cuba, the leftovers of afternoon convection there.
Now that it is late evening, a few small showers are starting to
reach north to near Key West. The 01z HRRR shows a few additional
showers developing south of the Middle and Lower Keys overnight
and moving north toward the island chain, especially between about
Sugarloaf and Vaca Keys. Indeed, the 00z KEY sounding showed a PW
value of 1.41" and a capping inversion just below 10,000 feet,
which is also similar. With so many similarities to the last 2
nights which have seen no thunder, have removed thunder from the
forecast for the rest of tonight.
Any showers will lift north of and away from the Keys around or
very soon after sunrise on Sunday. This will leave a mostly dry
and sunny day behind.
The deep low center that is moving across the Tennessee Valley
late tonight will exit up the Ohio Valley on Sunday. A trailing
cold front will weaken significantly as it approaches the Keys on
Sunday night and passes the Keys on Monday. Some low-level
convergence along and in advance of the front could squeeze out a
few showers on Sunday night and Monday as surface winds veer
around out of the southwest then northwest. Am growing more
skeptical on thunder chances.
Upper level high pressure will grow strong over the Keys on
Tuesday, with the 500 mb forecast map showing a 591 decameter high
centered directly over the Keys. This will keep surface-based
moisture too shallow from Monday night through Tuesday for any
noteworthy shower activity, even as surface winds turn from north
.LONG TERM...(Tuesday night thru Saturday)
From Previous Discussion: Surface ridging will slowly move east
driving a similar moderate gradient across the Keys thru the week.
Chance for showers will still be slight thru Wednesday Night, but
temperature highs and lows will return above normal Tuesday thru
Wednesday night. For Thursday through Saturday, ample moisture
will be in place and given convergence, have maintained a low
chance for showers, 30%. This will be out ahead of another
approaching trough which will transport abundant moisture out of
the Caribbean Sea allowing for elevated chances for rainfall.
Above normal for mid to late April.
.MARINE...Winds have been rising this evening at ob sites from the
Middle Keys to Pulaski Shoals, with both Smith Shoal and the NAS
on Boca Chica Key recently gusting to 24 knots. This made for an
easy decision to expand the SCA to include all marine zones except
Florida Bay. Looks like winds will be peaking over the Lower Keys
around midnight, then late tonight over the Upper Keys.
Winds will ease during the day on Sunday in advance of a weakening
cold front that will pass the waters on Monday morning. High
pressure will then move across the Southeast on Monday, at first
bringing northerly winds to the Keys. As high pressure move off
the Carolina coast on Tuesday and out to Bermuda on Thursday,
winds will turn out of the east, then southeast by mid-week.
Moderate to fresh southeast breezes on Wednesday and Thursday.
Mostly VFR conditions expected for the next 24 hours at the island
terminals. The only exception could be during the upcoming
overnight period, when a few showers moving north across the Lower
and Middle Keys could bring temporary BKN cigs in the 018-025
range. Otherwise, looking at the usual FEW-SCT coverage of fair
weather cumulus clouds during the day on Sunday, with bases in
the 020-025 range.
GM...Small Craft Advisory for GMZ032>035-042>044-052>055-072>075.
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Area Forecast Discussion
National Weather Service New Orleans LA
411 PM CDT Sat Apr 13 2019
Basically two systems to deal with in this forecast package. First
is responsible for the severe weather threat late this afternoon
through tonight. Second will bring another chance of severe
Starting with today... Storms have been a little slower to move
east than originally thought. While there have been some scattered
showers across the northern zones today, there has been very
little lightning at all in our entire forecast area thus far. Main
action is still off to the west and north of the local area. That
won`t be the case forever though. The surface low should start
moving more quickly toward the northeast in the next few hours. In
turn, this will force the convective focus farther east as well.
Still looking like a significant threat of severe weather, with
impressive shear and instability values as the main focus moves
eastward through tonight. Original thinking was that a squall
line would solidify and progress through the area, but all day the
CAM runs have struggled to solidify a QLCS. This could be both
good and bad. The good news is that broken lines tend not to
produce as widespread damage as solid lines with bows. The bad
news is that individual cells are more conducive for tornadic
development. And in fact, the HRRR has been hinting at a broken
line of cyclic rotating storms as the system moves across the
area, with the more impressive storms being across the northern
half of the area. This lines up well with the SPC outlook for
potentially significant tornadoes which runs along/north of a line
from Lafayette to Hammond to Hattiesburg. Timing is tough to nail
down, but expect the main threat timing to begin around 6pm or
7pm for our far west/northwest zones. It will progress eastward
through the evening and overnight, and the threat should be over
before daybreak across our far eastern zones on the MS Coast.
Also of note is the strong winds that we have been experiencing
well ahead of these storms. A tight pressure gradient has led to
widespread sustained winds of 20 to 25 mph with frequent gusts in
the 30 to 35 mph range. Several sites have also been reporting
occasional gusts near or just over 40 mph. Wind will continue
howling until the cold front gets closer and the pressure gradient
relaxes a bit, likely around midnight.
The trailing cold front will usher in much cooler weather for
tomorrow with highs generally only reaching the upper 60s to lower
70s most places. Strong cold air advection will also lead to a
second round of strong winds, and another wind advisory may be
needed mainly on the south shore of Lake Pontchartrain. Winds will
begin to drop off tomorrow night as the high becomes centered
closer to the area. Lows should drop into the mid to upper 40s
north and in the lower 50s south, which is around 10 degrees lower
than normal for this time of year.
The high shifts eastward by Monday night, with winds turning
onshore again and beginning the return flow process as another low
pressure system takes shape over the plains states. This system
looks to bring another threat of severe weather to the area
sometime from late Wednesday through Thursday. SPC has currently
outlooked the area for Thursday, which is unusual given the 6
day lead time. CIPS analogs also continue to hint at potential for
severe weather during this time frame. Given the lead time,
there`s not a lot of detail to be gleaned at this time, but it`s
certainly something to monitor as we move into next week.
Main concern is severe weather impacting terminals
through the evening and overnight hours. Broken line of storms
should begin to approach BTR and MCB between 01-03z and then work
east approaching ASd and MSY/NEW around 03-06z and then coastal MS
GPT/PQL around 05-10z. These storms could be severe with damaging
winds and even tornadoes possible. Have indicated winds of 30-35kts
with gusts of 45-50kts. LLWS may become an issue this evening as the
wind right at the sfc begin to back off a tad but just off the deck
remain around 40-50kts.
Strong onshore flow will continue to ramp up throughout the
afternoon and evening with small craft advisories in affect for
all marine zones from Saturday morning through 12Z Sunday. A front
will pass through the waters toward daybreak, and in the wake of
the front, expect strong cold air advection to strengthen the
winds even further. Have issued a Gale Watch for all of the open
waters in effect from 12z Sunday through 00z Monday, and have
extended the small craft advisory for the lakes and sounds for the
same time frame. Winds will begin to relax late Sunday night as
surface high builds in overhead. A light return flow will take
hold by Tuesday and continue through Thursday. Another strong
system expected Thursday evening with northwest winds expected
Friday and into the weekend behind the system.
DSS code: Orange.
Activities: Moderate risk of severe weather through tonight
Wind Advisory through midnight
River flood warnings
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or high
visibility event; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or advisory
issuances; radar support for slight risk severe or excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical
events; HazMat or other large episodes.
Red = Full engagement for Moderate to high risk of severe and/or excessive
rainfall, or direct tropical threats; Events of National Significance.
.PRELIMINARY POINT TEMPS/POPS...
MCB 55 63 43 75 / 80 10 0 0
BTR 55 65 45 75 / 60 10 0 0
ASD 60 69 45 74 / 80 10 0 0
MSY 60 69 52 74 / 80 10 0 0
GPT 63 70 48 72 / 70 10 0 0
PQL 65 74 45 75 / 70 10 0 0
LA...Wind Advisory until midnight CDT tonight for LAZ034>037-039-040-
GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ530-532-534-
MS...Wind Advisory until midnight CDT tonight for MSZ068>071-077-
Coastal Flood Advisory until 1 AM CDT Sunday for MSZ080.
GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ532-534-536-
Rest of Discussion...95/DM
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
630 PM CDT Sat Apr 13 2019
.SHORT TERM... (Through Late Sunday Night)
Issued at 431 PM CDT Sat Apr 13 2019
A strong Spring storm system is moving through the central portion
of the U.S. This system will bring a variety of weather to the
forecast area over the next 24-30 hours including rain, a chance of
a few thunderstorms, and likely some snow to portions of northeast
Missouri and west central Illinois. Current radar is showing a rain
shield moving up from Arkansas in to southern Missouri. Short range
models show strong moisture convergence along and south of the 850mb
front tonight as the central of the storm system moves up from the
lower Mississippi Valley into the Tennessee Valley. Most models are
showing elevated instability across southern Missouri and southern
Illinois tonight...and the latest runs of the RAP show 300+ J/Kg
MUCAPE as afar north as east central Missouri into south central
Illinois. This may be a bit much especially given the much more
conservative values that the NAM and GFS are showing. None-the-
less, I did bump thunderstorm chances slightly further
north...especially after midnight tonight to account for the
potential for a bit more instability. Regardless of how much
thunder there is, all that moisture convergence should produce
plenty of rain across the area tonight with as much as 1 to 1.5
inches across southeast Missouri and around an inch as far north as
a line from Columbia MO to Pittsfield IL. The deformation zone
precip will move across the area in the wake of the warm advection
late tonight and early Sunday morning. Forecast soundings continue
to look cold enough to support a change over from rain to snow as
this occurs across parts of northeast Missouri and west central
Illinois. Boundary layer conditions may be iffy, but it does look
like there will be enough dry air being pulled in behind the storm
in the low levels for temperatures to cool enough for the snow to
get all the way to the ground. That being said...2 inch soil
temperatures are pretty warm in the low 50s at this time. If
snowfall rates are high enough though some accumulation is
likely...how much is still uncertain given the antecedent
warmth...but up to 1 inch on grassy and elevated surfaces still
Precipitation should end from southwest to northeast from mid-
morning through mid afternoon. Temperatures are not expected to
rise above the mid 40s in most locations on Sunday. A weak ridge is
expected to build across the region Sunday night into early Monday
morning. At this time, it looks like dew point temperatures will be
in the low 30s with temperatures falling into the low to mid 30s as
well. This would be an excellent set up for frost for the area...so
we`ll need to monitor this closely for a possible Frost Advisory
.LONG TERM... (Monday through Next Saturday)
Issued at 431 PM CDT Sat Apr 13 2019
Spring returns on Monday after a cold start with southerly flow
ahead of the next storm system spinning up over the Great Plains.
Temperatures should rebound into the 60s and low 70s under
strong mid-April sunshine. The warming trend will continue on
Tuesday under the influence of south-southwest flow as the Plains
storm continues to gain strength. Ridging aloft along with 850mb
temperatures pushing 14-15C should be good for highs in the mid 70s
to around 80. The next chance for rain begins developing late
Tuesday night into Wednesday as the main upper level wave moves off
the Rockies into the central Great Plains. The stacked system
pushes into Kansas by 00Z Thursday and the GFS and ECMWF look to be
in good agreement that there will be showers and thunderstorms
developing ahead of the system in the mid Mississippi Valley
Wednesday into Wednesday night. Showers and thunderstorms continue
into Thursday with the potential for lingering light rain on the
western side of the system as it pulls away from the Mississippi
Valley Friday into Saturday.
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 620 PM CDT Sat Apr 13 2019
Forecast remains on track with rain currently spreading north into
the area. Current obs show visbys along the initial thrust of rain
dropping to MVFR, so went ahead and dropped visbys to 4SM in the
STL metro TAFs where rain is expected to be the heaviest. Cigs
will drop to MVFR a few hours after the onset of rain and continue
to drop through the night, reaching IFR in the early morning
hours at the STL metro TAFs. A light rain/snow mix is expected
for locations near UIN. Precipitation will clear out of the area
tomorrow morning, though reduced flight categories will linger
through much of the day thanks to ample lingering moisture.
SPECIFICS FOR KSTL:
The main difference at STL will be the intensity of the initial
shot of rain and the cigs tomorrow morning. It appears as though
the rain at STL will be strong enough to drop visbys to IFR
before relenting somewhat around 06z. Cigs will then fall through
MVFR into IFR by the early morning hours. The good news is that
cigs should at least crawl into MVFR shortly after the precip
clear out of the region.
Area Forecast Discussion
National Weather Service Blacksburg VA
1115 PM EDT Sat Apr 13 2019
A strong cold front will bring rain and an enhanced risk for
severe thunderstorms to the region Sunday and Sunday night.
Following the front, high pressure will settle over the region
for the first half of next week.
.NEAR TERM /THROUGH SUNDAY/...
As of 1110 PM EDT Saturday...
Enhanced Risk for Severe Weather and a Marginal Risk for
Excessive Rainfall Sunday and Sunday Night...
Low clouds had advanced north to a Bluefield to Lynchburg line
and will continue to spread over the rest of southeast West
Virginia and southwest Virginia overnight. Have slowed down the
chance of rain along the southern Blue Ridge and foothills this
evening in line with current radar trends and close to the
timing of the HRRR and Hires guidance through 8AM/12Z. Have
added some fog in the mountains where the ridges will be in the
clouds and where the temperature/dew point spread was near zero.
Muggy overnight lows expected with readings in the upper 50s to
Active weather pattern with strong storm system to impact the
region Sunday. A favorable set-up for severe weather Sunday per
strong mid- upper level trough poised to advance across the Ohio
Valley and into the Appalachians during peak heating Sunday. A
deepening area of low pressure is forecast to move east-
northeast across the Ohio Valley through the day Sunday, and
then across the central-northern Appalachians Sunday evening.
Showers and thunderstorms are forecast to be ongoing in a
north- south pre-frontal band from Indiana to Alabama Sunday
morning. As modest heating of a moistening pre-frontal warm
sector commences, 500 to 1000 J/kg mixed-layer CAPE is expected
to evolve ahead of the ongoing band of convection, from the Ohio
Valley to the Gulf Coast. This should result in a gradual
intensification of storms through the afternoon, aided by a very
strong deep-layer wind field accompanying this storm system,
including 60+ kt south-southwest flow at mid levels. A second
round of storms will accompany the cold front Sunday evening and
Primary storm mode Sunday afternoon is progged to begin
cellular, then gelling into complex bows and rotating updrafts.
Damaging winds will likely be the primary threat, though
tornadoes also a possibility. Risk should diminish gradually
through the evening, though gusty post frontal gradient winds
will likely persist through Sunday night and into Monday.
Heavy rain may become a concern pending persistence of the
thunderstorm activity. However, confidence is low attm with
respect to flooding as the storms are expected to be transient.
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 130 PM EDT Saturday...
Sunday evening, a surface cold front will head east of the
area, and then be following shortly behind by the parent upper
level trough axis by midnight. Indicators are still looking
promising for robust shower and thunderstorm activity as the
system passes through the region, along with the potential for
locally heavy rains. Southside Virginia and neighboring portions
of north central North Carolina have had multiple days now of
brief heavy rains, so this region will be in particular need for
The Storm Prediction Center is still outlooking the region to
be within Enhanced and Slight risk areas with the greatest
threat being straight line winds and large hail with a lesser,
but not zero, potential for an isolated tornado.
Once we get past about midnight Sunday night, the area will be
on the backside of the upper trough, and 850mb winds will
increase significantly from the northwest. Guidance has been
persistent, thus confidence is rising, that Wind Advisory level
gusts may be obtained through a generous portion of the second
half of Sunday night through the daytime and perhaps early
evening hours of Monday. Likewise, also at this time, there has
been persistence on the wind gusts not reaching High Wind
Warning criteria. Therefore, we are a little too early in time
for the hoisting of a Wind Advisory, and a High Wind Watch is
not looking probable, so we will continue to reflect the
appropriate wind speeds and gusts in the forecast grids, and
continue to highlight the concern in the Hazardous Weather
These gusty northwest winds will help to maintain upslope cloud
cover and isolated scattered precipitation across mainly the
higher terrain of southeast West Virginia, south into the
Northern Mountains of North Carolina Sunday night and early
Monday morning. As notably colder air rushes into the region, a
few of the highest peaks within this region may see rain showers
change, or mix with, snow showers by daybreak Monday, and
receive a light coating of snow on the ground, generally less
than one-half inch. Coverage of the precipitation and cloud
cover will decrease on Monday as drier air continues to progress
rapidly into the area.
The pressure gradient, and thus the wind speeds/gusts, will
slacken as we progress through Monday night into Tuesday. High
pressure will dominate our weather pattern with dry conditions
and limited cloud cover Tuesday and Wednesday.
Temperatures during this portion of the forecast will trend
cooler, with readings averaging around normal for this time of
year by Tuesday.
Confidence in this portion of the forecast is moderate to high.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 230 PM EDT Saturday...
During this portion of the forecast, we will encounter a
weather pattern similar to what is playing out across the region
today into tomorrow.
An upper level trough is expected to deepen over the Rockies
and head eastward into the Central Plains states where it
develop into a strong upper level low during the Wednesday into
Thursday time frame. A strong southerly fetch of moisture will
race north from the Gulf of Mexico in advance of this system and
progress into our region. The upper low`s associated cold front
is expected to cross our area Thursday night into Friday. Model
vary on the timing, but currently this is the general span of
time offered for this occurrence. Some guidance track an
additional shortwave trough northward along this front on
Friday, slowing its departure, and thus keeping the potential
for active weather into Friday night. The parent upper low and
its associated trough axis is expected to cross the area
Saturday or Saturday night.
What the above scenario means for our region will be
temperatures on the mild side in advance of this approaching
upper low/trough. Plenty of moisture and lift to have showers
probable Thursday through Friday, and perhaps even Friday night.
Thunderstorms, some potentially on the strong side thanks to
notable low level shear and marginal SBCAPE, will be possible
Friday afternoon and evening.
Cooler weather and gusty northwest winds are expected behind
the system, but this detail currently will fall outside the
extent of our seven-day forecast, more within the Saturday night
into Sunday time frame.
Temperatures during the Wednesday through Friday time frame are
expected to average 10 to 15 degrees above normal. On Saturday,
readings will be closer to 5 to 10 degrees above normal.
Confidence in this portion of the forecast is moderate. The
biggest question is how any change in timing of the upper low
and its associated surface features will impact the sensible
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 750 PM EDT Saturday...
A cold front extended from eastern North Carolina to a low in
northern Louisiana this evening. This front will move north as
the low tracks into the Great Lakes. The cold front will this
system will bring two bands of thunderstorms across the Mid
Atlantic region on Sunday, mainly in the afternoon and evening,
with MVFR ceilings and visibilities, very heavy rain and gusty
wind. Some of these storms may be severe with damaging winds and
Tonight IFR to LIFR ceilings are expected to develop across much
of southeast West Virginia, southwest Virginia and northwest
North Carolina. Areas of MVFR fog are also likely, especially in
locations that had rain Saturday morning, including KDAN and
KBCB. If the stratus develops first, the areal extent of fog may
be limited but ridges will be obscured.
Winds will be light out of the southeast tonight but will become
south ahead of the front Sunday morning with increasing wind
speeds and gusts of 20 to 25 knots.
Confidence is average for the ceilings and above average for the
thunderstorms and wind. Confidence is below average for fog and
EXTENDED AVIATION DISCUSSION...
A front shifts east to the mountains by late Sunday with
showers/storms, some strong to severe, so expect poor flying
conditions at times into late Sunday night.
Monday should be returning to VFR as high pressure builds in,
aside from lingering upslope MVFR in the mountains. Winds will
be strong and gusty behind the front Monday.
High pressure will keep Tuesday through Thursday VFR.