Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/22/18
Area Forecast Discussion
National Weather Service La Crosse WI
603 PM CDT Thu Jun 21 2018
.SHORT TERM...(Tonight through Friday)
Issued at 250 PM CDT Thu Jun 21 2018
A closed low continued to slowly sink southward across southwest
Iowa and into northwest Missouri today. Associated band of light
to moderate rainfall on the north side continued to impact the
forecast area throughout the day, but was narrowing somewhat by
the early afternoon. Dry east/northeasterly winds should continue
to erode away at the showers through the evening.
Meanwhile, a line of storms fired along the cold front associated
with the low and will move north along with the front into this
evening. Not expecting these storms to get into the forecast area
though, given lack of instability from all day cloud cover and
precipitation, and overall southern movement of the low.
Most of the rain should be out of the forecast area by mid-morning
on Friday as the center of low pressure will be over southern
Illinois/Indiana, though could see some lingering showers across far
southern Wisconsin into eastern Iowa. Otherwise, another day with
the northern half of the forecast area being warmer than the
southern half due to cloud cover, with highs ranging from the lower
70s south of Interstate 90 to the upper 70s north of Interstate 90.
.LONG TERM...(Friday night through Thursday)
Issued at 250 PM CDT Thu Jun 21 2018
Much needed drying takes place Friday night into Saturday as that
closed low continues to move east of the region and fills. Very weak
interim area of high pressure builds in with high temperatures right
around seasonal normals in the upper 70s/lower 80s.
Showers and a slight chance of thunderstorms creep back in late
Saturday night into Sunday as a weak mid-level trough rotates
southeast through the area. Look for highs in the upper 70s to lower
80s.
On/off shower and isolated thunderstorm chance will be seen Monday
through Thursday with the best chances centered around the
Tuesday/Tuesday night time frame as a fairly vigorous mid-level
trough/closed low rotates across the region from the Northern
Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 603 PM CDT Thu Jun 21 2018
Light showers continue across the area in the weak zone of
frontogenesis in the 1000-700 mb layer on the north side of the
upper level low that was over northern Missouri. As the upper
level low moves southeast, the frontogenesis will also move south
and weaken which will allow the showers to end at both airports
this evening. Even with the light rain, conditions are VFR and
this should continue through the night with the ceilings gradually
going up before the clouds scatter out Friday morning. Some
concern for fog development overnight with lots of low level
moisture in place along with light winds. Forecast soundings from
the 21.21Z RAP suggest the winds just above the surface will be at
or above 10 knots through the night which should be strong enough
to prevent much fog from developing.
&&
.HYDROLOGY...
Issued at 250 PM CDT Thu Jun 21 2018
Periods of light to moderate rainfall will continue into the
overnight hours before coming to an end for most of the area by
mid-morning on Friday. The main impact has been rises on area
rivers and streams, with the most recent being mainly across
southeast Minnesota and northeast Iowa. In addition, river levels
across western Wisconsin will remain elevated, with minor
flooding expected along portions of the Mississippi River from
rainfall in past days.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...CA
LONG TERM...DAS
AVIATION...04
HYDROLOGY...CA
Area Forecast Discussion
National Weather Service Grand Junction CO
829 PM MDT Thu Jun 21 2018
.UPDATE...
Issued at 827 PM MDT Thu Jun 21 2018
Winds have subsided across the forecast area so critical fire
weather conditions are no longer being met. The Red Flag Warning
has been allowed to expire. The Red Flag Warning for tomorrow
continues. Some midlevel clouds continue to stream across the area
but with the sun setting, do not anticipate any convection so
removed mention of storms in forecast. Rest of forecast looks
good.
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 348 PM MDT Thu Jun 21 2018
Some showers have developed across the north as anticipated but no
lightning strikes as of mid afternoon. Anticipating more virga
than anything as the low levels are very dry. This activity is all
ahead of an approaching shortwave trough currently trekking
through northern Idaho into western Montana. The winds are finally
starting to become breezy in some spots this afternoon but had a
tough time to start. Critical fire weather conditions are more
probable over northwest Colorado where the gradient is a little
better and a Red Flag Warning remains in place through this
evening. Expect isolated shower activity with low potential of a
lightning strike or two late in the day across the northern
mountains through sunset. Temperatures today are already on their
way to 5 to 10 degrees above normal as Grand Junction already
sits at the forecast high of 96, compared to 89 degrees
yesterday.
Temperatures will remain warm, above normal on Friday though
slightly cooler than today due to the aforementioned shortwave
trough and associated cold front moving through the area as the
low moves southeast through Wyoming into the Dakotas. Isolated
thunderstorms are possible over the northwest Colorado mountains
as this shortwave trough clips the area. Winds will increase as
well with a shift in winds to the northwest Friday afternoon with
trough and cold front passage. These windier and drier conditions
will result in critical fire weather conditions becoming more
widespread to include much of eastern Utah and western Colorado.
Upgraded the Fire Weather Watch to a Red Flag Warning for Friday
and expanded the area to include southeast Utah as well as the
Eagle area. Details are included in the Fire Weather section below
and in the DENRFWGJT (Red Flag Warning) product. Due to this
northwest wind shift, the latest experimental HRRR smoke model is
showing smoke from the Trail Mountain Wildfire across the north
and central areas today into this evening with the smoke
transporting to the southeast across east- central Utah into
southwest Colorado by Friday afternoon. This includes the Moab
area, so put this in the forecast through Friday night.
.LONG TERM...(Saturday through Thursday)
Issued at 348 PM MDT Thu Jun 21 2018
Winds will relax somewhat behind the passing shortwave trough as
shortwave ridging moves overhead on Saturday. The gradient
tightens late in the day on Saturday ahead of another upper low
dropping into southern Idaho. Some isolated showers and
thunderstorms are possible over the eastern Uintas as the jet
rounding the base of this trough sets up over northern Utah. This
upper low will move through Wyoming on Sunday and into northeast
Utah by Monday morning. An 85 kt jet will round the base of the
upper low with its axis directed over southeast Utah into the Four
Corners for potential for critical fire weather conditions as the
atmosphere remains dry with better chance for breezier conditions.
Still looks marginal at this time, but will be something to watch.
This upper low will also bring much cooler temperatures into the
area Sunday with temperatures some 5 to 8 degrees below normal.
The chance for showers and thunderstorms will also increase as
this upper low moves across on Sunday, with northern and central
mountains being favored for convective activity as well as
increased cloud cover. This should keep relative humidity above
critical levels for these regions. There is still some discrepancy
in the models on how quick to move this low out of the region. The
EC is quicker with Monday being drier as the low moves into the
northern High Plains, while the GFS hangs on through Monday as
the low wraps up over northeast Colorado into the Nebraska
panhandle by Monday. Temperatures are expected to rebound towards
normal by Monday with mainly dry conditions with a chance of
storms remaining over the northwest Colorado mountains.
Temperatures will make a quick return to well above normal
Tuesday through Thursday as a ridge of high pressure expands from
the desert southwest across the area. This will result in hot and
dry conditions with some lower valleys of east-central and
southeast Utah into west-central Colorado approaching triple
digit heat.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 516 PM MDT Thu Jun 21 2018
A few gusty winds of 20 to 25 kts noted across the area this
evening but they should die down in the next few hours. Tranquil
conditions overnight with clear conditions. Tomorrow, an upper
level disturbance will bring another round of gusty winds of 25 to
30kts in the afternoon. All TAF sites will see some gusty winds. VFR
conditions will remain in place.
&&
.FIRE WEATHER...
Issued at 348 PM MDT Thu Jun 21 2018
An approaching trough and weak cold front will cause winds to
increase this afternoon where conditions remained dry. Winds will
be strongest over northwest Colorado with isolated, mostly dry
thunderstorms possible. A Red Flag Warning remains in effect
until 8 PM for Colorado fire zones 200 and 202.
On Friday, the cold front will slowly move through the area and
strong and gusty surface winds will expand over across the region
in response to an increase in the surface pressure gradient.
Much of eastern Utah and western Colorado will experience critical
fire weather conditions where fuels are dry so the Fire Weather
Watch has been upgraded to a Red Flag Warning and expanded to
include a couple more zones. A detailed listing of the fire zones
included in the watch can be found in the Watch/Warning/Advisory
section which follows this discussion.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning from 10 AM to 9 PM MDT Friday for COZ200-202-
203-205-207-290>295.
UT...Red Flag Warning from 10 AM to 9 PM MDT Friday for UTZ486-487-
490-491.
&&
$$
UPDATE...TGR
SHORT TERM...MDA
LONG TERM...MDA
AVIATION...TGR
FIRE WEATHER...TGJT
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1009 PM EDT Thu Jun 21 2018
.SYNOPSIS...
Shower and thunderstorm chances will persist through Sunday as the
region remains in a warm and humid airmass to the southeast of a
low-pressure system over the lower Great Lakes. A cold front will
drop into the forecast area on Monday ushering in a more seasonable
and drier airmass for next Tuesday and Wednesday before humidity
increases Thursday ahead of the next cold front.
&&
.NEAR TERM /THROUGH FRIDAY/...
Evening Update...Ongoing convec across the NW Piedmont will continue
to track NE of the FA thru the next hour or so. Not expecting much
more than SPS level strength with these storms...but they will
produce high rainfall rates and plenty of CTG lightning. The latest
HRRR has a good handle on the current activity and indicates the
middle TN storms will dissipate as they reach the Apps. PoPs were adj
downward overnight and isol -shra with a perhaps a tstm or two will
linger into the early overnight period as the upper low and difl
zone continue pushing toward the FA. Expect mtn valley fg overnight
and perhaps across the rest of the area where winds go light as sfc
tdd/s are running low over areas that received rainfall.
700 PM Update...made some downward tweaks to temps across the
non/mtns where a swatch of heavy showers and thunder storms have
dropped values about 5-7 degrees. Expect the CLT area to be under the
gun for tstms...heavy downpours and gusty winds for the next hour
with isol thunder and -shra elsewhere over the FA thru 03z.
500 PM Update...No sigfnt changes made to the going fcst. Convec
potential is better across the wrn zones as low sfc td/s have
limited mlCAPE to under 500 J/kg across the ern Upstate and NC
piedmont. Expect a couple ts warnings over the next few hrs across
NE GA as an h5 s/w traverses east and enables deep convec along a
llvl theta/e ridge axis.
As of 2:15pm EDT Thursday: Somewhat broad 500mb trough is currently
digging into the southcentral CONUS and begins pulling northeastward
on Friday. Passage of this feature will improve wind shear and
dynamical forcing over the area, and is expected to increase
severity and coverage of afternoon thunderstorms. 500mb winds
improve to 45kts on Friday, and a couple lobes of PVA cross the CWA
ahead of the main system. However, BL instability does not improve
much and MLCAPE remains below 1000 j/kg. Most models do not have
heavy precipitation with this event, but with some forcing and
generally in-place moisture, above CLIMO coverage of afternoon
thunderstorms is anticipated both this afternoon and tomorrow
afternoon. Improved deep layer shear to 30kts will keep some risk
for severe weather with these storms. Heaviest precipitation is
expected in western upslope areas, with average rainfall declining
downslope south and east of the Southern Appalachians.
Some increase in cloudiness and a drop in thicknesses may moderate
highs a few degrees, but highs today and Friday are still expected
to be slightly above normal. Surface pressure pattern remains weak
as main low associated with upper system tracks around the southern
Great Lakes region, keeping the main front out of the GSP area. A
secondary low/weak lee trough east of the Mountains does not change
much the next 36 hours, with generally light southwesterly flow
prevailing at 5 to 10kts.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 245 PM EDT Thursday: While the western Atlantic Ridge becomes
suppressed south and retrogrades east Friday night, the upper level
low pressure system across Indiana will shift toward northeast Ohio
and weaken. Spokes of energy will continue to traverse our forecast
area (FA), as a result we will maintain some POPS but lower the
values across the board. Generally chance in the mountains and
slight chance in the piedmont. The NAM and European models also
favor this solution, in varying modes.
On Saturday and Saturday night the upper level flow flattens over
our region, but remains rather strong for this time of year. The
models show a minimum in convection, however considering the moist
and unstable atmosphere, and various flavors of lee side troughing
or left over boundaries, suggests keeping POPS in at least either a
chance or slight chance category. In our eastern FA there seems to
be more of a mid level cap which could hold back convection.
Also of note during this period, in the fast flow aloft, the NAM is
trying to drive some complex of storms Saturday evening across our
south FA. Although this would fit nicely on the southern end of the
stronger upper flow. However, our other deterministic guidance do
not offer that solution. Although, the European model has something
reaching our mountains at daybreak Sunday. Of course if any of this
plays out it would complicate the forecast Sunday.
Our call then Saturday night, we dropped off all POPS during the late
evening in the piedmont, but held onto chance in the mountains and
parts of our western FA, with the idea something could arrive late.
On Sunday we will be a little above persistence for POPS in the
mountains. This again is part of the instability and moisture, a
decent looking wave in the mean flow (which is subtly changing from
westerly to W-NW). Meanwhile, once again surface troffing and
potential outflows, could yield some convection. If any of the
aforementioned clusters of storms are true, this might change the
configuration of thunderstorm activity.
The guidance if rather close in this sticky airmass and we only
deviated slightly. Looking at heat indices, we do have a few values
around 100 degrees in the piedmont. We will watch this carefully.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 300 PM EDT Thursday: The extended period begins with an
upper-level trough axis passing overhead and the associated cold
front will be dropping through the forecast area through Monday
morning. The front will be slow to work completely through the area
on Monday and guidance differs on how long moisture and PoPs will
linger along and near the boundary. Nevertheless, given the time
of year and north-to-south progression of the front, a slow passage
and lingering moisture is reasonable underneath northerly flow aloft
downstream of the trough. We also are just displaced to the south
and west of the right-rear quadrant associated with the upper-level
jet which should help to maintain some shower activity Monday.
Therefore, the official forecast generally maintains but slowly
diminishes chance PoPs through Monday evening, with the longest
chance persistence in the Piedmont (closer to the frontal boundary).
Heights build aloft Monday evening heading into mid-week ahead
of a closed upper-low beginning to lift out of the northern
Great Plains. However, the primary influence on our sensible
weather will be the lower-level flow associated with expansive
high pressure extending from the southern Appalachians to Bermuda.
As mentioned in previous forecast cycles, model guidance continues
to stubbornly disagree on the extent of easterly moisture flux
and resultant upslope around this high pressure system, with the
ECMWF remaining moist and the GFS (and now the Canadian) drier.
In the latter models, an Atlantic moisture fetch is intermittent
whereas the ECMWF is stronger and more persistent. The blended
guidance maintains chance PoPs Tuesday and Wednesday across much
of the forecast area. The official forecast trended drier for
now and kept only slight chance PoPs across the area, especially
from the mountains south and east across the Upstate. Regardless,
high temperatures will drop back to near, if not a degree or two
below-normal on both days and the modified maritime airmass will
lower dewpoints back into the lower and mid 60s outside of the
mountains so it will be notably more pleasant.
The center of the ridge will gradually migrate north and east
from the lower Mississippi River Valley into the Ohio Valley
by the end of the week but first a weak shortwave trough drops
into the Mid-Atlantic late Thursday into Friday morning with an
attendant surface trough. The low-level flow will veer S and
SEly Thursday morning allowing higher temperatures and humidity,
and more summerlike PoPs, to return ahead of this trough.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: The main concern with the TAF set will be the
ongoing tstms lined up SW of the CLT terminal. Have tempo -tsra with
gusty winds thru 03z. Previous storms this evening have been
producing gusts arnd 35 kts or so with VSBY dropping into the IFR
range. Kept VSBY in the MVFR range at KCLT as storms are weakening
in a lower mlCAPE environ. No good chance of deep convec activity
elesewhre this evening...but showers will linger into the early
overnight period. Expect lowering CIGS and VSBY to MFVR/IFR at KAVL
and KHKY overnignt and possibly across the Upstate sites as well due
to the high precip rates. Better confidence is had with the NC sites
tho...so will leave out of the non/mtn terminals for now. Another
sct/num convec afternoon Fri...thus have PROB30s covering -TSRA
generally aft 18z all sites.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 83% High 98% High 100%
KHKY High 100% High 100% High 97% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 97% High 98% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JMP
NEAR TERM...SBK/WJM
SHORT TERM...TS
LONG TERM...JMP
AVIATION...SBK
Area Forecast Discussion
National Weather Service Wilmington NC
949 PM EDT Thu Jun 21 2018
.SYNOPSIS...
Hot and humid conditions with scattered thunderstorms will
continue through the weekend. A cold front will move through
the area Monday night. Drier and cooler conditions are expected
to gradually develop Tuesday and Wednesday of next week and may
persist into next Thursday as high pressure builds in from the
north.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 945 PM Thursday...Scattered showers and a few embedded
thunderstorms moving east across the SC Midlands and NC Piedmont
will soon be in the Pee Dee region. There has been no
significant change in forecast thoughts for the overnight period
as this wave of scattered convection moves through. Severe
weather potential appears quite limited, and forecast PoPs
remain in the `chance` range. Discussion from 645 PM follows...
Large CAPE values up to 3000 J/kg have been feeding towering
cumulus development all afternoon along the seabreeze and inland
as well, however dry air aloft has limited the area to just a
smattering of rainfall so far. Shower activity should diminish
almost entirely over the next hour, however a weak trough
associated with an enhanced area of t-storms now entering
western South Carolina may lead to a resurgence of convection
later this evening. Activity may redevelop across Lumberton and
the Pee Dee region by 10 PM, then should clear out of the Cape
Fear region by 3 AM. I`m not expecting severe weather, but
scattered showers and thunderstorms with 30ish percent coverage
sounds reasonable.
Otherwise no significant changes have been made to the forecast.
Assuming convection doesn`t become overwhelmingly widespread,
lows should remain very warm tonight with mid to upper 70s for
most areas. -TRA
Discussion from 300 PM follows...
Convective temperatures being realized this afternoon. GOES_E
visible reveals storms firing along a west to east remnant
outflow to the north across central NC. A weak surface trough
axis was analyzed from around AKQ to OCW to EYF to KMNI.
Vertical circulations from morning ACC clouds has aided the
blossoming of convection over central and SE NC. The present
steering flow will take some of the cells into the sea breeze
directly later this afternoon, which could pulse cores close to
severe thresholds. Still appears to be some inhibition aloft in
part due to short-wave thickness ridging ahead of the
approaching upper trough, however this influence will migrate
eastward into late afternoon and early evening.
Tonight, a broken line of convection ahead of an upper trough
should edge from west to east into our forecast area, with
diurnal cooling and remnant dry mid-level air serving to lessen
convective intensity. A few strong to severe storms may linger
north of Pender and Bladen counties into middle and late evening
where convergence and diffluence aloft will be stronger. The
line may bring a brief wind shift to NW-N overnight.
Heat and humidity will be short of Heat Advisory criteria on
Friday, but apparent temperatures will reach 100 degrees.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Deep low pressure over the juncture of
the Ohio and Mississippi Rivers Fri evening will continue to
lift N-NE leaving a broader, flatter flow by Sat night. A trough
will extend down from this low toward the Gulf Coast states
leaving a deep SW flow running up through the Carolinas but as
low lifts off, flow aloft will veer to a more westerly
direction. Looks like some shortwave energy rotating around the
trough may enhance some convective development which is always
tough to time exactly. But, there will also be some drier air
moving in with the SW to W flow aloft. Overall not expecting any
widespread development, but any storms that do blossom could be
quite potent depending on the timing of the mid to upper
impulses moving through, with main focus along sea breeze
boundary and trough inland.
Temps will once again soar into the 90s with overnight lows in
the mid 70s most places. With slightly drier air moving into
the I-95 corridor Sat aftn, expect heat index values to hold
just shy of heat advisory criteria, but still hot.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Ridge will be suppressed to our S Sun
and Mon as an upper trough pivots across the Northeast states
and then offshore Tue. Shortwave energy embedded in the W to WNW
flow will skirt across the Carolinas with one spoke moving
across and offshore Sun night into Mon morning and another late
Mon and Mon eve. This should help drive a surface cold front
south and into the area Mon night into Tue. High pressure will
then try to build S Tue and Wed which should push the front
further S where it will stall out Wed and Thu.
This scenario should allow for the greatest coverage of showers
and thunderstorms early in the week, especially Mon and Mon
night when precipitable water values will peak near or in excess
of 2 inches. Convection should be scattered Sun, initiating
along the seabreeze and Piedmont trough. A greater number of
thunderstorms may arrive Sun night coincident with upper level
support which should be able to sustain upstream thunderstorms
as they move into our portion of the Carolinas. The arrival of
progressively drier air from the N Tue and Wed should result in
a decrease in convective coverage and silent POPs may be
warranted for at least portions of the area Wed and Thu.
850 mb temps will reach 20-21C Sun and so expect the heat and
humidity to still be high with high temps reaching the mid and
upper 90s. This will bring the heat index to near 105 to 109
which would require a Heat Advisory. We should be at least a
degree or two cooler Mon with more clouds and developing
convection and then seasonable temps Tue through Thu as
dewpoints lower to the mid and upper 60s which will keep heat
index values below 100 degrees. Lows Sun night will still be
muggy, mid and upper 70s, but lower 70s should be more common
for the remainder of the week.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
As of 00Z...There will some instability overnight and it should be
enough to kick off some late evening convection as a weak impulse
movers through around 03Z. The HRRR model does not do much with it,
but it does have some good convection developing in the Morehead
City area after midnight. Will keep VCSH as a hedge. Little or no
fog expected. Friday, another hot one with isolated convection by
afternoon.
Extended Outlook...VFR with possible short duration MVFR fog or
IFR cigs inland terminals early each morning. Scattered
afternoon showers and thunderstorms likely each day with short
duration restrictions possible. A cold front will bring a better
chance for showers and thunderstorms Monday.
&&
.MARINE...
NEAR TERM /THROUGH FRIDAY/...
As of 945 PM Thursday...The seabreeze died a quick death this
evening, but synoptic winds continue at 10-15 kt, even a bit
stronger out at the Frying Pan Shoals buoy. No significant
changes are needed to the forecast with this late evening
update. Discussion from 645 PM follows...
Only a modest seabreeze was able to develop today despite
firecracker heat inland. It`s so warm over the ocean now in late
June that even 95 degrees inland isn`t that great a temperature
difference anymore. Background southwesterly winds 10-15 kt
should continue through the evening, but the passage of a weak
trough offshore late tonight should veer winds more westerly
with speeds dipping to 10 knots or less before sunrise. Seas
currently 2-3 feet could briefly build toward 4 feet near Cape
Fear later this evening, but should average 3 feet through the
night. -TRA
Discussion from 300 PM follows...
SW winds prevail into evening, because of TSTM steering flow,
it is advisable that mariners get a radar updated before heading
out because of potentially active marine weather tonight, most
of it north of Cape Fear and the Gulf Stream. Seas will hold at
around 3 ft, with dominant wave periods of 5 seconds. No
advisories or caution headlines are expected but periodic gusts
to 20 kt can be expected both tonight and on Friday, and 4 ft
seas outer waters at times. Winds and seas will be higher and
near TSTMS.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Low pressure over the Ohio Valley will
lift north through Saturday and tighten the gradient flow late
Sat into Sat night a bit. Overall expect SW winds 10 to 15 kts
with gusts to 20 kts, but winds should reach up to 15 to 20 kts
late Sat into Sat night. This should push seas up a bit with
some 5 fters possible in the outer waters and beyond through Sat
night into early Sun. Also, expect a spike in winds and gusts
in afternoon sea breeze, especially close to the coast.
LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 300 PM Thursday...SSW to SW winds Sun will be mainly SW
Mon and then shift to the N and NE in the wake of a cold front
late Mon night and then NE to ENE Tue as high pressure begins
to assert a southward push across the waters. The strongest
winds will be in the range of 15 to 20 kt later Sun afternoon
and eve, the result of a robust seabreeze circulation, and into
Sun night due to some nocturnal jetting. A tightening gradient
ahead of a cold front approaching from the N may keep wind
speeds close to this range into Mon. Wind speeds will diminish
to 10 kt late Mon night. A modest push of drier and cooler air
should bring wind speeds up to around 15 kt Tue. Seas will be 3
to 4 ft with a tendency to build to 4 to 5 ft during Tue.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...TRA
NEAR TERM...MJC/TRA
SHORT TERM...RGZ
LONG TERM...RJD
AVIATION...JDW
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
907 PM CDT Thu Jun 21 2018
...SEVERE THUNDERSTORMS POSSIBLE LATER TONIGHT THROUGH AT LEAST
FRIDAY NIGHT ACROSS PORTIONS OF THE REGION...
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Scattered thunderstorms have slowly dropped south out of TN into
northern MS the last few hours and the HRRR shows this southward
sag continuing after midnight. While instability has waned with
the loss of heating, a slug of rich theta-e air in the lower
levels continues to feed the convection from the southwest. This
along with 40-45 knots of bulk shear are still maintaining a few
decent updrafts. The HRRR and latest NAM are showing the
convective area continuing to wane after midnight and now only
skimming the far northern portions of the forecast area. Have,
thus, pushed the marginal severe area farther to the north and
decreased pops to the south of there./26/
Prior discussion below:
Through Friday:
Lead low level trough in advance of main height falls in association
with southern fringe of incoming big upper disturbance is now
shifting to our southeast. Most of the concentrated heavy rainfall
and storms will shift to the southeast of the Pine Belt
concurrently, although isolated to scattered thunderstorms will
remain possible over the remainder of the forecast area through
early evening. The previous MARGINAL risk of severe storms through
the afternoon has been removed as the probability of convection deep
and vigorous enough to take advantage of increasing environmental
shear is not very good until tonight. Temperatures have been kept
down a bit in most areas by the clouds and rain, but some upper 80s
to low 90s readings creeping back toward the MS River is juxtaposed
with dewpoints running in the mid to upper 70s, which of course is
delivering some unpleasant heat index values near to a little above
the century mark. This pocket of oppressive conditions will be
increasingly on our door step (and sometimes smashing through the
door) over the course of the next handful of days.
As I write this there are potent storms headed through the Midsouth
where enough atmospheric lift has materialized to spur deep
convection in an environment of 2000+ MLCAPE and deep layer shear
approaching 40 kts. The cold front triggering the storms is headed
through central AR, but likely will not get a lot farther before
stalling just to our northwest and north through tomorrow. As this
happens the environment capable of generating the current severe
storms heading toward Memphis will shift equator-ward (more into our
region) as the driving upper disturbance pushes east/southeast and
increases lift and shear over our region. We will likely start to
experience the tangible impact of this across far northern zones
tonight as potentially potent convective clusters forming upstream
push east/southeast and bring at least an isolated damaging wind
risk to the Highway 82 corridor. Worthy of mentioning that low level
shear will be marginally supportive of a stray spin-up tornado late
tonight through tomorrow with any organized thunderstorm clusters in
our region. The latter is definitely not the main risk, but it is
something to keep in mind. The larger risks will be hail and
especially damaging wind gusts.
The overall threat for severe storms will increase tomorrow.
Current expected scenario is that a combination of
thunderstorm outflow pressing south and the stalled boundary to our
northwest/north will trigger thunderstorms which will probably
quickly grow upscale into one or two potent thunderstorm clusters
that race east/southeast through at least the northern half of the
region through the day. There is uncertainty with how far south this
activity may get; at this point we cannot rule out that
thunderstorms and the attendant gusty wind threat gets all the way
to the southern fringes of the forecast area. Working CAPE values
tomorrow pushing 3000 j/kg in concert with deep layer wind shear
approaching 40 kts is a rather rare combination in our region for
the 2nd day of summer. Everyone should remain weather aware through
tomorrow and understand some of the thunderstorm activity may be far
from the typical summer-time rumbles. /BB/
Friday night through Thursday...
The forecast period will start off Friday night with a closed
mid/upper-level low over the Ohio River Valley and an associated
shortwave trough axis extending through the southeast states.
Zonal to northwest flow will be in place across the ArkLaMiss
ahead of a subtle shortwave trough and speed max ejecting out of
the Rockies and into the Southern Plains. This feature will help
to kick off a complex of thunderstorms over Oklahoma Friday night
along a stalled frontal boundary that will be draped from west to
east into northern Mississippi. This thunderstorm complex is
progged to track along the frontal boundary and into northern
portions of the area along the Hwy 82 corridor Saturday morning
into the early afternoon hours. The environment will be supportive
of isolated strong to severe thunderstorms with 20-30kts of deep
layer shear, ample instability, and respectable lapse rates. While
a marginal risk for severe weather may eventually be needed, the
placement will be highly dependent on the convective evolution
both today and tomorrow and the placement of any residual outflow
boundaries. Therefore, will hold off on mention in the
HWO/graphics for now but the potential will bear watching.
For the remainder of the weekend and into early next week, the
main headline will shift from thunderstorms to heat stress as
mid-level ridging builds north into the area keeping the better
flow and shortwave troughs displaced north over the Middle
Mississippi River Valley. High temperatures will gradually climb
into the low to mid 90s Saturday through Tuesday with low to mid
70s dewpoints supporting heat index values in the 100-105 degree
range across much of the area. This heat will be confined further
south on Saturday before spreading north by Sunday into Monday
and Tuesday. Will continue to advertise the ongoing limited risk
in the HWO/graphics for heat stress and a day or two of heat
advisories cannot be completely ruled out.
By mid to late next week, global model solutions begin to
diverge, however there is general agreement that the center of
the mid-level ridge will become further removed to the north of
the ArkLaMiss region with easterly flow helping to support
isolated to scattered diurnally driven thunderstorm chances by
Wednesday. There are also indications that a weak inverted trough
could retrograde beneath the ridge across the northern Gulf of
Mexico late next week which would further reinforce increasing
thunderstorm chances, especially across southern portions of the
area. While temperatures will still be in the low 90s, the
potential for storms and clouds to cut back on heating leads to
lower confidence on heat stress continuing further into the week,
although this will need to be evaluated on a daily basis. /TW/
&&
.AVIATION...
00Z TAF discussion:
VFR conditions will prevail through a good portion of the evening,
but VCTS will become possible toward midnight between GLH, GWO and
GTR. Further south, MVFR/IFR ceilings will develop over JAN, HKS,
MEI and HBG and persist through mid morning Friday. Thereafter,
ceilings will rise to VFR, but VCTS will become possible at all
TAF sites. Where thunderstorms occur, a brief lowering of ceilings
and visibilities will be encountered along with gusty winds./26/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 74 90 74 93 / 7 45 18 11
Meridian 72 91 74 93 / 11 54 28 12
Vicksburg 75 90 75 92 / 5 47 18 6
Hattiesburg 73 93 75 94 / 8 22 10 4
Natchez 74 91 75 91 / 4 19 8 3
Greenville 75 88 74 91 / 26 69 33 28
Greenwood 74 86 74 91 / 31 69 30 34
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1106 PM EDT Thu Jun 21 2018
.UPDATE...
Issued at 1105 PM EDT THU JUN 21 2018
Visibility at the Morehead Airport temporarily dropped to less
than one-quarter mile. This appears to be rather isolated in
nature based on other observations and webcams, and the visibility
has bounced back up to 10 miles at SYM. The nighttime
microphysics satellite view is showing some fog may also be
developing in Pike, Knott and Floyd counties in river and stream
valley areas. Have added patchy dense fog to the NDFD, mainly in
valley areas and mentioned patchy dense fog in HWO. As was the
case at SYM, dense fog may be short lived at any given location
with clouds generally on the increase and scattered showers still
around.
UPDATE Issued at 846 PM EDT THU JUN 21 2018
Radar continues to show scattered showers across the forecast
area, mainly in two bands, with one over the far northeast part
of the area and the other from near Mount Vernon to near
Middlesboro. More organized thunderstorms over western KY have
shown a weakening trend with satellite showing warming tops. There
has also been a rapid decrease in lightning with the western KY
storms. The HRRR has been consistent over the past several runs
showing the western KY convection decreasing as it moves east, and
this is confirmed by recent observational trends. Have updated
the overnight forecast mainly for recent convective trends, but
this did not result in much change in the overall forecast. Have
left the possibility of thunder in the forecast for the next
couple of hours with the shower chance gradually diminishing
through the night, and finally bottoming out around 20 percent.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 425 PM EDT THU JUN 21 2018
Upper level low over the Northern Plains will drop southeastward
and through the lower Ohio Valley during the period and then lift
back to the northeast into Ohio by late Friday night. Surface low
pressure will follow a similar track through the short term. An
occluded frontal boundary will move into the Commonwealth tonight
ahead of these other features but will dissipate before making it
into our half of the state. However, the front reforms by the time
the parent low slides into southern IL Friday morning. This
reformed boundary will then move eastward across the Commonwealth
through the day Friday, reaching eastern Kentucky by early
evening.
There will be a marginal risk for severe weather across the area
late Friday afternoon and early evening as the front approaches.
As a result some storms could produce some gusty winds and
possibly some marginally severe hail should we get enough sunshine
through the day. At present MLCAPEs could approach 1500 J/kg. This
combined with effective shear of about 35 kts may allow for a
couple of stronger storms to develop. Again, limiting factor
would be instability and much will depend on how much sunlight and
heating we manage to see through the day.
.LONG TERM...(Saturday through Thursday)
Issued at 354 PM EDT THU JUN 21 2018
A frontal boundary will push east across the region and possible a
surface trough in the wake as the surface low tracks northeast.
Opted not to go completely dry given the weak trough and a nearby
upper level shortwave. The frontal boundary will slow and become
more stationary near the border or in the Tennessee Valley. This
will interact with ripples in the quasi-zonal upper level setup
and lead to a several rounds of showers and thunderstorms.
However, given the models have shown variability in the upper
level and surface features, i.e the front now projected to be
further south, will lean toward the MOSGUIDE and blended guidance
that remains in the likely range for POPs. Despite the
uncertainties, I can see POPs increasing once some of the details
are more resolved. Good news, once this system moves south and
east on Monday, we will see high pressure build southeast and
provide a stretch of dry weather for the most part through
Wednesday. Then warm and moist air will return by late next week
and lead to increased chances of showers and thunderstorms and
more summer like airmass.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 736 PM EDT THU JUN 21 2018
Scattered showers continue to affect the area early this evening,
and some lightning is still possible until 03Z or so. Stronger
thunderstorms over western Kentucky are moving east, but these
are expected to diminish with the loss of daytime heating. Some
showers may linger in our area until after 06Z, but trends are for
a decrease in shower coverage through the night. VFR conditions
will prevail to start the period, but ceilings are expected to
lower later tonight, and some fog is possible in at least a few
locations. MVFR ceilings and localized MVFR visibility is forecast
for late tonight, thought some local IFR conditions cannot be
ruled out. After 13Z on Friday conditions will again improve to
VFR. As a cold front approaches Friday afternoon thunderstorms
will be possible across the entire area. Some of the storms Friday
afternoon could be strong.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...RAY
LONG TERM...DJ
AVIATION...SBH
Area Forecast Discussion
National Weather Service Lubbock TX
621 PM CDT Thu Jun 21 2018
.AVIATION...
TS over northeastern NM progged to move to the ESE or SE through
the evening. Model consensus brings these storms to the vicinity
of KCDS around 08Z. The HRRR is an outlier in bringing these
storms closer to KPVW and KLBB. Will monitor advecton of the
storms through the evening and insert mention in the appropriate
TAFs when confidence increases. Otherwise VFR conditions are
expected through Friday.
&&
.PREV DISCUSSION... /issued 349 PM CDT Thu Jun 21 2018/
DISCUSSION...
The forecast area remains under northwest flow aloft today and the
latest satellite imagery shows some t-storm activity currently
developing along the higher terrain of northern NM. The low-level
jet is expected to develop tonight and may give this activity a
better chance of sustaining itself as it makes a run southeast
toward the forecast area this evening. The latest few HRRR runs
have been trending more toward the activity approaching our
northern counties around midnight, and perhaps making it into
the Rolling Plains before it dissipates early Friday morning. We
have expanded the PoPs across our north and northeast counties
tonight, but they may need to be expanded even further if a small
MCS develops.
On Friday, a more energetic shortwave will be crossing the
Rockies, with pressure falls increasing the southwest breezes
across the region. Temperatures will also increase, and highs
should be in the upper 90s to lower 100s across the forecast area.
It appears there will be the potential for some t-storm
development within the pressure trough across the western counties
late Friday due to the convergence and strong heating. The cap
will be more difficult to break with southward extent, so at this
time we expect the development to be isolated south of the
Panhandles, but we have added a mention to the forecast. We`ll
also be watching the potential for another MCS to propagate
southeast Friday evening and possibly brush the far southeast
Panhandle and northern Rolling Plains.
Another outflow-enhanced cold front is progged to make it`s way
into our forecast area Saturday. At this time, this boundary does
not appear as strong in the guidance as Wednesday`s but it will
depend on the extent of the convection Friday night. With some
uncertainty in the particulars, we will indicate slightly cooler
temperatures across most of the forecast area during the day,
along with a chance of t-storm development across the southern
Rolling Plains, in the vicinity of where the boundary may stall
out Saturday afternoon.
An upper-low over the central and northern high plains Sunday
should keep most of the action to our north, although with
temperatures rising back into the upper 90s and low 100s we can`t
completely rule out a few diurnal storms. And we should see a
similar situation on Monday with that upper-low moving very
slowly. It should be slightly cooler Monday as the trough axis
moves across West Texas, and t-storm chances look to be best
across the southeast Panhandle into the northern Rolling Plains.
The upper ridge broadens across the southern tier of the CONUS
Tuesday and the slowly migrates northward through the end of the
week. This should keep the forecast area hot and dry. The upper
trough may shift far enough northeast by next weekend with a large
trough coming into the west that we`ll see cooler temperatures and
perhaps some moisture moving back in from the southwest.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07
Area Forecast Discussion
National Weather Service Memphis TN
910 PM CDT Thu Jun 21 2018
.DISCUSSION...
Severe thunderstorm watch has been allowed to expire and the main
line of convection has moved into Middle TN along with the Mid
level shortwave that helped fuel the activity. More convection
has developed across North MS along the outflow boundary generated
by the earlier storms. An isolated severe threat for mainly
damaging winds will continue for the next couple of hours with
0-6km bulk shear values of around 40 kts and SBCAPES around 2000
j/kg to the south of the outflow boundary. Latest HRRR indicates
convection should push south of the area after midnight. Patchy
fog possible after midnight.
SJM
&&
PREV DISCUSSION... /issued 210 PM CDT Thu Jun 21 2018/
The Midsouth was becoming increasingly unstable ahead of an
approaching cold front extending from southeast Missouri into
central Arkansas. Radar showing spotty convection forming along
and ahead of the boundary with one lone severe storm. In the wake
of the overnight precipitation skies were currently a mix of cu
and sun over the area with temperatures in 80s. Dewpoints were in
the low 70`s and winds were breezy from the west southwest. SPC
meso-analysis was indicated CAPE amounts of 1000 to 2000 j/kg with
effective bulk shear of 35 kts.
For this afternoon through tonight...CAMs are agreement that
current storms will intensify and congeal into a broken line over
the remaining afternoon hours and into the evening as the front
tracks through the region. A few storms likely to produce damaging
winds and large hail. A SVR watch has been issued through 9pm for
most of the CWA. Activity should scour out the atmosphere across
the northern and western counties by late this evening...leaving
higher pops to remain across North Mississippi after midnight.
Overnight lows will drop to around 70F with some patchy fog
forming. General rainfall totals will range between a half to
potentially two inches.
Friday through Sunday...models are in very good agreement that the
current upper level low in northern Missouri with drop into the
St. Louis area tonight...then slowly track towards the Eastern
Great Lakes through Saturday becoming an open wave. This will
leave a west northwest upper flow over the Midsouth of 30-50kts
with embedded shortwaves likely to trigger new storms. The first
of these disturbances will arrive tomorrow night and a second late
Saturday into early Sunday. So rain chances will continue to be
stout this weekend shifting from the southern counties to the
northern counties as the aforementioned upper low pulls northeast.
A few strong to severe storms will also suffice in this better
sheared environment. Temperatures from precipitation and lingering
cloud cover will be seasonal with highs ranging from the mid 80s
to near 90...with lows in the upper 60s and low 70s.
Monday through next Thursday...expected daily rain chances to
slowly dwindle this period as long range model solutions show
upper heights building. 90F+ temperatures will return along with
triple digit heat indices. Heat advisories may be required for
portions of the area.
JAB
&&
.AVIATION...
/00z TAFs/
Thunderstorms will continue to move east across west TN and
portions of north MS over the next several hours with generally
dry conditions anticipated at the forecast terminals beyond 05z.
There is some indication that IFR ceilings will develop over
north MS late tonight and patchy fog will be possible in areas
that clear out. Otherwise, expect VFR conditions through the
period Expect scattered storms again on Friday, mainly across
north MS. Winds will increase from the west by mid- morning.
Johnson
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
955 PM EDT Thu Jun 21 2018
.DISCUSSION...A line of showers and thunderstorms is moving across
middle Tennessee and northern Alabama. The latest HRRR model
suggest this line will move into the CHA area around 04Z, but soon
dissipate afterwards with more widely scattered showers and storms
the rest of the night.
Due to the expected breaks in the cloud cover and recent rains, do
expect more patchy fog across the region early Friday morning.
Have made some minor changes to hourly temperatures and lows, but
overall current forecast looks good.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 71 86 70 87 / 50 70 60 40
Knoxville McGhee Tyson Airport, TN 68 84 68 86 / 50 60 60 30
Oak Ridge, TN 69 84 68 86 / 50 70 60 30
Tri Cities Airport, TN 65 83 65 83 / 50 60 50 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
800 PM CDT Thu Jun 21 2018
.UPDATE...
Issued at 800 PM CDT Thu Jun 21 2018
Given the latest radar trends, updated the forecast to cancel Severe
Thunderstorm Watch 196 across the remainder of the forecast area.
Scattered showers and isolated thunderstorms will continue to be
possible through the night--and may become more common later in the
night--as the upper low draws closer. However, waning instability
should preclude any further severe potential for the nighttime hours.
The remainder of the forecast is unchanged.
UPDATE... Issued at 725 PM CDT Thu Jun 21 2018
Cluster of thunderstorms continues to shift east across the far
southern Pennyrile region of western Kentucky, thus the clearing of
additional counties from Severe Thunderstorm Watch 196 per the WCN
product. Given the mini supercell structure that produced the
tornado reports over far southeast Missouri, we decided to keep the
watch in effect for far southern portions of western Kentucky. This
was collaborated with WFO Memphis and based on the tick up in
instability depicted by the HRRR model over far western Kentucky
through early evening. Will reevaluate within the next hour or so
based on radar trends.
Also, the aviation discussion was updated.
&&
UPDATE... Issued at 550 PM CDT Thu Jun 21 2018
Strong convective line of storms continues to shift east across
western Kentucky near and east of the Land Between the Lakes area.
Atmosphere ahead of the line remains characterized by modest
instability with SBCAPE values of 1000-1500 J/kg. While the line is
slowly outrunning the best deep layer shear, 0-6 km bulk shear on
the order of 30-35 knots will continue to support localized storm
organization as the activity shifts east across the remainder of
western Kentucky through early evening. Given the severe
thunderstorm warned cell east of the Lakes, decided to extend Severe
Thunderstorm Watch 196 east to encompass the rest of our Kentucky
counties along and south of McLean and Webster to the Tennessee
border.
.SHORT TERM...(Tonight through Saturday night)
Issued at 117 PM CDT Thu Jun 21 2018
Short res analysis shows pm convective band(s) developing in
1500-1900 J/KG MUCAPE field. IR tops generally AOA -45C. Shear
should be increasing as jet pivots this way, heightening pot svr,
but thus far only marginal storms. New SWODY1 outlooks slgt risk
into early evening.
HRRR marches convective band(s) west to east across FA thru 00Z.
More isolated to widely scattered showers/storms linger across FA
thru the evening hours, with a 2ndary band pivoting across our
east, hinted at by the short res modeling. The upper Low tracks
into scntl IL by 12Z tmrw morning, and then lifts to near IND by
the end of the day (00Z Sat). Until then, scattered to likely pops
will linger.
After the Low pulls out, drier relative air invades with dew
points dropping into the mid 60s and a teleconnected upper ridge
bumping across the mid Ms river valley Friday night into Saturday.
This short-lived break will see a returning frontal boundary warm
sector again, from the south and west, as increasing moisture and
another chance of showers/storms enters the forecast from that
direction and spreads northward and eastward Saturday night.
Convection/clouds and slightly drier air will bring welcomed
relief on the mercury, with upper 70s to lower 80s tmrw, returning
to lower to middle 80s Saturday.
.LONG TERM...(Sunday through Wednesday)
Issued at 322 PM CDT Thu Jun 21 2018
On Sun, with a stalled frontal boundary just to our south, and
weakening west-northwesterly flow aloft, scattered, diurnally-driven
showers and tstms should continue in the moist and unstable
atmosphere. PoPs will be highest near the KY/TN state lines. Sun
night and beyond, the models generally indicate that the likelihood
of pcpn will wane significantly as the pattern aloft goes anti-
cyclonic, and slightly drier air is introduced into the PAH forecast
area from the northeast.
On Tue, warmer air is progged to sweep back into our region on
southwesterly low level winds, as a nearly stacked low pressure
system moves from the central Plains to the Great Lakes. There
should be enough warm air aloft to preclude shower and tstm activity
for us in the early part of next week, with the possible exception
of late Wed/Wed night, when the ridge may be suppressed enough for
isolated showers and tstms to develop north of I-64 and in the
eastern third of the PAH forecast area. After a seasonable start to
temps, the extended forecast period will have a general warming
trend, especially mid-week on. Conditions are forecast to become
more oppressive later in the week, with heat indices in excess of
100 mainly on Wed and Thu afternoons.
&&
.AVIATION...
Issued at 725 PM CDT Thu Jun 21 2018
The center of a mid level low pressure system will roll through the
region overnight. This will result in scattered to isolated shower
activity overnight, with little chance of lightning as the
atmosphere stabilizes. VFR conditions are expected to dominate most
of the night, with a limited possibility of brief MVFR vsbys in
showers, less so west of the MS River. However, by around sunrise,
MVFR cigs associated with the low are expected to develop across
much of the region, mainly east of the MS River. These clouds should
linger through much of the day, with some improvement seen late in
the planning period. As the atmosphere destabilizes again during the
day, showers are most probable in the Evansville Tri-State region,
with some possibility of tstms.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...RJP
AVIATION...DB
Area Forecast Discussion
National Weather Service Pueblo CO
548 PM MDT Thu Jun 21 2018
.UPDATE...
Issued at 548 PM MDT Thu Jun 21 2018
Updated to add isolated pops across northern El Paso County
through the early evening.
&&
.SHORT TERM...(This evening through Friday)
Issued at 245 PM MDT Thu Jun 21 2018
Not much convection across the area this afternoon, as only some
weak cells have formed in nern NM and west of KDEN as of 21z.
Mesoanalysis and HRRR suggest activity will remain sparse this
evening, with best chance of a storm from the NM border eastward
into Baca county. Could also see some virga/sprinkles drop south
across Teller and nrn El Paso counties early this evening before
activity dies toward sunset. Overnight, strengthening low level jet
may provide enough lift to keep a slight chance of tsra going
through the night along the CO/KS border, though better forcing
would appear to be just southeast of the area in the TX Panhandle.
On Friday, upper wave passes to the north of the region, with band
of stronger mid/upper level winds moving across srn CO during the
afternoon. Air mass looks dry enough to drop humidity below 15
percent over the mountains and along the srn I-25 corridor, and will
convert the Fire Wx Watch to a Red Flag Warning, plus add Teller
county/Pikes Peak, as drier air will spread eastward into the area
from Park county by afternoon. On the plains, low level moisture and
instability lurk along and just east of I-25 through the day, with
last couple runs of the NAM holding the moist air slightly farther
west than the GFS. Will certainly have enough CAPE (1000-2000 J/KG)
and shear (0-6km around 50 kts) for storms over the plains by
afternoon, though with upper support fairly far to the north, storm
initiation will be the main problem. Best guess is convergence along
the Palmer Divide and far east end of the Raton Mesa will be enough
to develop at least isolated convection, with storms potentially
intensifying as they reach the more unstable air near the KS border
toward 00z. Certainly a threat for large hail over the far east,
with SWODY2 slight risk covering much of the southeast plains
looking reasonable.
.LONG TERM...(Friday night through Thursday)
Issued at 245 PM MDT Thu Jun 21 2018
Models remain in good agreement through the extended period and
ensemble spreads remain low. This all leads to higher forecast
confidence through the extended period.
Friday night...strong to severe thunderstorms are expected to be
ongoing near the Kansas border Friday evening. These thunderstorms
will have developed along a dryline and will be making their way
east into western Kansas through the evening hours. Large hail
will be the primary threat along with lightning. Expect the severe
activity to push off into western Kansas by midnight. Behind the
departing convection, a cold front will drop south across the
Plains and shift flow northerly through Saturday morning.
Saturday...upper level high pressure will build across Colorado
for Saturday with generally dry conditions expected across the
region. There will likely be enough residual moisture around to
produce a couple of weak afternoon and evening thunderstorms over
the mountains. Temperatures will also likely warm into the lower
to mid 90s across the lower elevations.
Sunday into Monday...an upper level low pressure center will drop
south out of the Northern Rockies and across northern Colorado
Sunday into Monday. The main concerns for Sunday will be the
potential for dangerous fire weather concerns over western
Colorado, and severe weather across the Plains. Gusty westerly
winds and expected low humidity values will likely produce
dangerous fire weather conditions over the Continental Divide, San
Luis Valley and Eastern Mountains on Sunday afternoon. This will
need to be monitored closely. Further east, much will depend on
where the dryline will develop. Current model projections indicate
severe weather will be possible from the Palmer Divide, southeast
across the Plains to Baca County. Large hail and gusty outflow
winds will be the primary threat. Expect most thunderstorms
activity to shift east of the area through the overnight hours. By
Monday, the upper system will be slowly making its way into
Nebraska. Wrap around moisture and upslope flow across the Plains
will likely lead to shower and thunderstorm development on the
back side of the upper low. Expect cooler conditions Monday with
80s for highs.
Tuesday through Thursday...the upper level low will continue to
lift away from the area with broad high pressure developing over
the Desert Southwest. This will build northward across Colorado
through the middle of the week with warming temperatures. Embedded
disturbances rotating up and around the high pressure to the
south will bring diurnally driven afternoon and evening showers
and thunderstorms to the mountains. This activity will likely
spread east into the I-25 corridor before dissipating with sunset
each day. Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 245 PM MDT Thu Jun 21 2018
VFR conditions at all taf sites overnight and through 18z on Fri.
Slight chance of a tsra returns to both KPUB and KCOS beginning 18z-
20z Fri, before activity shifts eastward across the plains around
00z. Hail and strong winds will be possible with any storms that
form on Fri, with a period of IFR cigs/vis under any stronger
convection.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Friday for COZ220>225-229-
230.
&&
$$
UPDATE...MW
SHORT TERM...PETERSEN
LONG TERM...MOZLEY
AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Blacksburg VA
1123 PM EDT Thu Jun 21 2018
.SYNOPSIS...
A weak stationary front just north of the area will sink south
into the region tonight before stalling into Friday night.
Upper level energy riding across the boundary will interact with
tropical moisture in place to produce scattered to numerous
showers and thunderstorms for the remainder of this week into
this weekend.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1115 PM EDT Thursday..
Lobe of vorticity combined with a layer of deeper moisture
convergence and residual instability keeping area of
showers/embedded thunderstorms going in the piedmont late this
evening. A couple of cells in Rockingham surged into severe
range, but as of this discussion, had only one tree down.
HRRR handling the latest radar trends well, and should see most
of the activity exit our piedmont by 2am. Thereafter, expect
mainly dry rest of the night with patchy fog, locally dense in a
few spots.
Previous early evening discussion...
Convection has exited the east, with two areas in the
mountains/foothills, one over southeast WV and another along the
Blue Ridge in Alleghany/Surry County, NC south into Wilkes. This
in association with a vort lobe moving across the southern
Appalachians early this evening.
High-res models have been running too hot on coverage, but
location is not too bad, so expect best coverage the rest of the
evening to stay in the mountains where models weaken the upper
vort lobe, but keep deeper moisture convergence. Given the lack
of very deep convection and the fact the storms are moving and
not as organized, will refrain from issuing any flood watches.
The 22z RAP has better handle on current radar trends and does
try to redevelop more showers/storms from near Roanoke northward
to the Alleghanys.
Will reshape pops to lean toward this solution.
Previous discussion from early afternoon...
Main concern with convective coverage into this evening including
possible hydro issues across the north near the surface front and
severe potential south/east where have seen more sunshine/instability.
However so far early arrival of showers over the mountains has acted to
curtail more widespread heavy rainfall, while deeper convection has
been slow to develop out east given lingering westerly downslope and
lack of support. Latest models continue to show quite a band of showers
with embedded thunder swinging from southwest to northeast this evening
as the vort axis aloft heads northeast and interacts with the surface
front oozing south. Most solutions support this scenario although
differ in the strength of the convective band and also speed of
movement with some Cam output very slow to move the heavier showers
northeast. This would mainly be along the I-64 corridor, swinging
southeast across Lynchburg and down into Southside Va this evening
before lifting out toward midnight. Thus keeping a similar swath of
categorical/likely pops this evening espcly north/east before diminishing
to mostly chance or less coverage overnight as the initial shortwave
lift/diffluence exits. Given the ongoing trend in seeing less
organization, potential weakening of convection toward loss of
heating, and rather high flash flood guidance, wont hoist a short
term watch for now but rather keep mention in the HWO for more
localized flooding per models 1-2 inches of QPF. Lows similar to
the past couple of nights but perhaps slightly cooler low/mid
60s north/west where more showers appear likely.
Surface front likely to be near the Blue Ridge early Friday with more
weak wedging out east and continued southwest flow west. Midwest upper
low to gradually shift east allowing another spoke of energy to push
into the mountains during the afternoon. This should support another
round of at least heavy rain producing showers and storms mountains
where instability west of the surface front will exist. Also models
indicate more shear as the low level southwest jet increases ahead of
the upper system. Models suggesting a bit better severe threat from
southwest sections per more heating, to along the front near the Blue
Ridge including southern sections where likely to intersect more in the
way of northeast flow resulting in better helicity. Continued tropical
Pwats within a stronger more unidirectional southwest flow could
also set the stage for multicellular bands capable of producing
added heavy rain espcly along the Blue where a watch may be needed
Friday pending rainfall from this evening.
Otherwise after some fog early, running with chance pops to start
before ramping up to likely and periods of categorical in the
afternoon, with less deep convection over the far northeast within the
weak wedge. Highs tricky pending where the front ends up and how
expansive clouds/showers are by afternoon. Mav mos remains less
aggressive with the wedge while the Met cooler espcly east
where spots may stay in the cooler 70s all day. Therefore went
closer to the warmer Mav west and a blend east which keeps quite
a range from 80s southeast to only lower 70s far north.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 245 PM EDT Thursday...
Low pressure in the Ohio Valley will lift northeast into New England
by Saturday night. The closed upper low over the Mississippi Valley
will move northeast and slowly open up.
Positive vorticity advection associated with the upper low tracking
out of the Ohio Valley will reach the Appalachians early Saturday
morning. Scattered showers and thunderstorms will continue into
Friday night, before departing to the northeast Saturday morning.
Low temperatures Friday night will range from around 60 degrees
to near 70 degrees in the piedmont.
Mean trough will travel east Saturday across the Mid Atlantic region
and pass to our east Sunday morning. Bulk shear Saturday will be
decent, LIs around minus 1 to minus 3 and cooler mid level
temperatures are all supportive of thunderstorms. SPC in day 3 has
placed a marginal threat of severe weather to our east along the
coastal plain north to Delmarva. Numerous showers and thunderstorms
are expected Saturday afternoon into Saturday night. Saturday highs
will be close to normal with readings from around 70 degrees in the
northwest mountains to around 90 degrees in the piedmont. Saturday
night low temperatures will vary from the the lower 60s in the west
to the lower 70s in the east.
Confidence for all elements is average.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 245 PM EDT Thursday...
A split flow upper-level pattern across North America will gradually
become more consolidated by the middle of next week.
Upper trough axis will continue to rotate east Sunday into Sunday
night. Scattered showers and thunderstorms are expected Sunday with
the best chance in the west. Shortwave crosses the region Monday
along with a surface cold front. GFS is strong and further south
compared to ECMWF.
A large ridge builds over the eastern United States Tuesday and
slowly moves east into Wednesday. 500 MB heights over the Mid
Atlantic region will be around 591dm. subsidence and warmer
temperatures aloft will suppress widespread thunderstorm
development. Will keep Tuesday and Wednesday near normal for
temperatures and mainly dry. The ECMWF allows fore some isolated
convection in the southwest portion of forecast area. A cold front
approaches from the west on Thursday.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
As of 725 PM EDT Thursday...
Mainly VFR this evening with some areas of MVFR with
showers/isolated storms. Best threat of this will lie from
Roanoke to Lewisburg, WV.
Late tonight, looks like showers will fade and/or move
northeast of our area, and amendments as necessary will occur if
showers/storms approach other terminals. With higher lower
level moisture the formation of a layer of low level stratus
tonight with cigs 500 to 1500 feet including patchy fog is at
least likely at most of the taf sites, with lowest cigs at
LYH/BLF/BCB.
Frontal boundary is expected to remain stalled over the region
through Friday. This boundary will be the focus for
showers/storms again on Friday mainly from 17z to the end of the
taf period with varying VFR to MVFR in clouds/showers with
local IFR in areas of heavier rainfall.
Confidence is medium to high that sub-VFR cigs/vsbys occur late
tonight at times at most sites, but lower as to extent/timing of
improvement Friday morning. Confidence low to medium on timing
of showers affecting the area around 04-9z, but higher that most
will see a threat of showers/some storms Friday afternoon, but
will not put thunder as predominate wx type and keep as VCTS
with moderate showers.
.Extended Aviation Discussion...
The front will lift back north Saturday followed by another
cold front passing through from the west on Sunday. This should
result in improving conditions over the weekend with only
periods of sub- VFR likely in more scattered nature showers and
storms through Sunday or Sunday night. Increasing moisture from
rainfall will also result in the opportunity for late night fog
and stratus for much of the period. High pressure spills in
from the north early next week perhaps finally making for a
period of VFR for Monday and Tuesday.
&&
.EQUIPMENT...
As of 200 AM EDT Thursday...
The NOAA weather radio transmitter in Hinton, West Virginia that
is WXM72 and broadcasting at a frequency of 162.425 MHz is off
the air. Parts are on order to repair the transmitter, but there
is no known time of restoration. We apologize for any
inconvenience.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/WP
SHORT TERM...KK
LONG TERM...KK
AVIATION...JH/PM/WP
EQUIPMENT...
Area Forecast Discussion
National Weather Service Tallahassee FL
954 PM EDT Thu Jun 21 2018
.UPDATE...
No significant changes to the previous forecast appear necessary.
Remaining evening convection will continue to diminish over the
next few hours. The 00z HRRR shows some redevelopment around dawn
along the eastern panhandle and big bend coasts, likely
associated with the land breeze. Left a chance of convection there
around dawn to account for that possibility.
&&
.PREV DISCUSSION [723 PM EDT]...
.NEAR TERM [Through Tonight]...
Weak upper level ridging in place this afternoon will continue to
break down tonight as an upper level low across the midwest digs
southward. Scattered showers and thunderstorms this afternoon will
diminish this evening, however the line of storms over southern MS
is expected to make it into western portions of the CWA after 00z,
although likely weaker with the loss of daytime heating. Given this,
highest PoPs tonight are across southeast Alabama, 20-30%, and 10-
20% elsewhere. Lows will be in the mid 70s with upper 70s along the
coast.
.SHORT TERM [Friday Through Saturday Night]...
In the upper levels a trough will be over the Southeast. At the
surface southwesterly flow will be over the region as a low moves
from the Midwest to the Northeast. Daytime POPs will be 30 to 40
percent on Friday and 10 to 30 percent on Saturday. Overnight POPs
will be less than 20 percent. Skies will be partly to mostly cloudy.
Highs will be in the lower 90s. Lows will be in the mid 70s.
.LONG TERM [Sunday Through Thursday]...
In the upper levels a ridge will be over the Southeast. At the
surface a weak pressure gradient will be over the region with high
pressure over the Atlantic. Daytime POPs will be 10 to 30 percent on
Sunday. Daytime POPs will be 40 to 50 percent next week as the high
weakens. Overnight POPs will be 20 to 40 percent. Highs will be in
the 90s. Lows will be in the 70s.
.AVIATION [Through 00Z Saturday]...
Scattered thunderstorms will continue to impact parts of our area
through sunset before dissipating. Terminals most likely to see
brief visibility reductions are VLD, ABY, and DHN. VFR conditions
are likely to persist overnight through the early morning.
Scattered thunderstorms are possible again during the late morning
at ECP, with highest chances in the afternoon at all other
terminals with brief visibility reductions possible.
.MARINE...
Moderate southwesterly winds will continue through the weekend. Seas
will be 2 to 3 feet through the weekend.
.FIRE WEATHER...
No fire weather concerns are expected over the next several days due
to humid conditions and light winds.
.HYDROLOGY...
A wet pattern will return next week. Local rivers are steady or
falling at this time. QPF over the next seven days is 1.25 inches or
less.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 74 92 74 93 75 / 20 30 10 10 10
Panama City 79 87 79 88 79 / 30 30 10 10 0
Dothan 74 92 75 92 75 / 20 30 10 20 0
Albany 76 92 75 94 76 / 20 40 20 30 10
Valdosta 74 92 73 93 75 / 20 30 10 20 10
Cross City 75 90 75 90 76 / 20 30 10 10 10
Apalachicola 78 89 77 89 78 / 30 30 10 10 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 5 AM EDT /4 AM CDT/ Friday for
Coastal Bay-Coastal Gulf.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...DVD
NEAR TERM...Fieux
SHORT TERM...McD
LONG TERM...McD
AVIATION...Lahr
MARINE...McD
FIRE WEATHER...Lahr
HYDROLOGY...McD
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
816 PM EDT Thu Jun 21 2018
.UPDATE (Overnight through Friday)...
00Z water vapor and H4 RAP analysis showing mid/upper level
ridging extending across the Gulf of Mexico and over the FL
peninsula this evening. This ridging lies beneath a
significant trough amplification for later June that is
digging from the MS valley into the eastern third of the
nation. While the main trough base looks as through it will
stay to the north of our region into Friday...it influence
will help suppresses the lower level/surface ridging axis
well to the south through the FL straits. A ridge position
this far to the south will provide a well- defined W/SW flow
pattern in the lower portion of the atmosphere across the
eastern Gulf of Mexico and Florida peninsula. Guidance
members are suggesting a 6-10 knot mean 1000-700mb flow for
the day Friday...which places Florida within a "Type #4"
summer flow regime...and resulting convective pattern for
later tonight through Friday. A type #4 pattern and its
light/moderate low level westerly flow is favorable for
isolated to scattered late night/morning showers to develop
over the warm waters of the eastern Gulf...eventually
migrating onshore toward dawn and through the morning hours.
Given the proximity of the upper trough to our north...
would suggest some enhancement and best coverage of showers
over the NE Gulf and along the Nature Coast. This potential
for showers migrating onshore last through the morning hours
as diurnal surface heating begins over the landmass.
Eventually we see a sea-breeze form (although generally
weak). This sea-breeze is pushed quickly inland by the
prevailing synoptic flow. Therefore...along the coast/I-75
corridor, there is a short window midday/early afternoon for
more robust sea-breeze storms, before the entire boundary
and best storms potential transitions to the interior parts
of the peninsula for the later afternoon/early evening
hours. Sinking air and loss of convergence in the wake of
the sea-breeze significantly reduces rain chances. Under
this type-4 pattern, a significant number of the west-
central and southwest Florida population centers see their
best rain chances before 2 PM...with a quick drop off in
rain potential thereafter. The forecast for Friday follows
this philosophy.
A greater potential for robust convection during the later
afternoon/evening hours along the I-75 corridor and coastal
western Florida peninsula takes place when the low level
synoptic flow is from the east and southeast. This direction
acts to hold the sea-breeze closer to the coast and the
opposing flows (sea-breeze from the west and synoptic flow
from the east) results in a region of prolonged and
enhanced convergence along the I-75 corridor. Flow regime
types #6 and #7 cover these scenarios, and are
characterized by the low level ridge (subtropical ridge)
axis lying across the northern half of Florida or even
across southern GA. There are indications that our forecast
will transition more toward one of these types of patterns
by the early portion of next week. For more information on
the total of 8 defined flow regime types, and the resulting
spatial and temporal convective pattern we generally see
from each here in Florida during the summer thunderstorm
season, please see our Thunderstorm Climatology website at:
http://www.weather.gov/tbw/Thunderstorm_Climatology
Forecasters will determine the daily flow regime # from
numerical modeling and real-time observations, and then use
these climatology datasets as one of the important input
into the timing and locations for the thunderstorm forecasts
from day to day.
&&
.AVIATION (22/00Z through 23/00Z)...
VFR conditions prevail across the region this evening.
Thunderstorm activity has progresses inland from the I-75
corridor and should not impact any terminals before
completely dissipating. W/WNW winds diminish after sunset
and remain light SW/variable through sunrise. A few isolated
showers can not be ruled out moving ashore from
KTPA/KPIE/KSRQ during the late night and morning hours.
Defined westerly flow developing on Friday will allow for
scattered storms through early afternoon for any of the
terminals...with greatest thunderstorm chances again moving
well inland from the I-75 corridor through the middle to
later afternoon hours.
&&
.Preliminary Point Temps/PoPs...
TPA 80 89 80 91 / 10 30 10 20
FMY 78 90 78 92 / 30 30 10 30
GIF 75 91 76 92 / 20 40 20 50
SRQ 80 87 80 89 / 10 30 10 20
BKV 76 89 76 90 / 20 30 10 20
SPG 79 90 80 89 / 10 30 10 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Saturday evening for
Coastal Sarasota.
Gulf waters...None.
&&
$$
Update/Aviation...Mroczka