Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/17
Area Forecast Discussion
National Weather Service Taunton MA
1026 PM EDT Thu May 18 2017
.SYNOPSIS...
After today`s record heat, we may see strong thunderstorms
tonight, especially in western New England. A cold front pushing
through the region Friday may trigger an isolated shower or
storm, mainly south of the Mass Pike. High pressure moves over
the region during the weekend bringing dry weather and more
seasonable temperatures. A weather system from the Midwest
sweeps east Monday with showers. Drier air moves in Tuesday.
Another weather system will bring showers on Wednesday and
Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1015 PM Update...
Line of strong to severe thunderstorms progressing across
central and northeast sections of southern New England.
Surface temperatures were remaining in the low to mid 80s across
much of eastern MA still at 10 PM, and mid level lapse rates
across much of southern New England were running 6.5 to 7+ at 10
PM. Although the line has shown some fragmentation in the last
10 to 15 minutes, a risk for severe wind gusts still persists. The
gust front with G30-35 KT has pushed ahead of the deep
convection. Hence, we are considering Special Marine Warnings
for the NE MA coast as far south as Boston Harbor.
We anticipate the activity will begin to settle down by around
midnight with a much lower risk of severe. May still have some
persistent convection even into the early morning hours with
some hint of an instability axis becoming established across CT.
Will need to keep an eye on the area later.
Have adjusted POPs in accordance with ongoing convection with
HRRR guidance for next 3 to 6 hours. Have also made some minor
adjustments in temperatures per current trends.
650 PM Update...
* Few severe storms still possible tonight in western New
England
* Most of activity may stay to our north but not confident
enough to remove threat in SNE
Still seeing temps in 90s across much of SNE this evening after
a record-setting day at BDL, BOS, PVD, and a tie at ORH (see
below). Winds have become more SW and will begin to diminish
around sunset.
Our focus remains on the potential for severe storms tonight,
especially in western New England. Activity has been focused
along axis of higher K-index values from northern PA into
central NY and northern New England. This will slowly shift
toward our area tonight, as we are already seeing moisture
increase on the latest precipitable water analysis. Dewpoints,
which dropped into 40s and lower 50s due to mixing, will slowly
increase as well.
High-res models continue to insist that activity now along NY/PA
border west of BGM will reach western New England around 10 pm,
then weaken as it heads into eastern MA and RI closer to 2 am.
Despite loss of daytime heating, it`s fairly cold aloft (-11C
at 500 mb) to help sustain convection. Mid level lapse rates
look favorable and 0-6km shear will be increasing over region
this evening, so our thinking remains same - that is, we see
lines or small clusters of storms tonight with wind damage
being main threat. This does not look like a widespread event
but one which features a number of strong storms (40 mph gusts)
and perhaps a few severe storms capable of producing wind
damage.
The limiting factor is fact that best synoptic scale forcing
associated with short wave seems to stay to our north across
northern New England (where storms are lining up now). But we do
have subtle height falls over southern New England which may be
enough.
Once any activity weakens overnight, expect clouds to linger
with patchy fog near South Coast. Lows should only drop back
into the 60s to around 70.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Cold front drops through region Fri. Enough lingering moisture,
instability, and convergence ahead of it to possibly trigger a
few showers or even a thunderstorm, especially south of Mass
Pike from late morning into mid afternoon.
Drier air arrives from NW during day, but many areas will still
top out in 80s. Forecast soundings once again show deep mixing,
so we should see 20-30 mph gusts at times Fri afternoon.
Clear and cooler Fri night with lows falling back into 40s and
lower 50s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Big Picture...
Longwave pattern is in transition next week with flow flattening to
zonal. A trough then digs over the Eastern USA while a ridge builds
along the West Coast. Shortwave scale shows Eastern high pressure
in control over the weekend. Upper low pressure over the Southwest
USA ejects across the plains to the Great Lakes by Monday, then
crosses New England Monday night/Tuesday. Another upper low dives
south from Canada and sweeps across New England Wednesday
night/Thursday.
Models are in fair agreement through Tuesday. Thereafter there are
differences in handling of the late week system. Confidence is high
for the weekend and early week. Confidence is moderate overall for
the late week storm, but with low confidence on details of timing.
Details...
Saturday-Sunday...
High pressure from Canada builds south over New England Saturday
with a northwest flow aloft. The high then moves overhead Saturday
night and Sunday. Expect dry weather through the weekend. Mid and
high level moisture increase during Sunday suggesting increasing
cirrus cover and possibly some mid level clouds.
Mixing levels look to reach 850 mb. Temps at 850 will be 5-7C both
days, which would support max temps in the mid 60s to low 70s. The
easterly flow off the water may buffer temps in Eastern Mass, thus
expect high 50s and 60s there Saturday, then temps a few degrees
warmer Sunday as the flow shifts.
Monday...
Shortwave over the Great Lakes moves east, driving a cold front
through NY/PA during the day and into Western New England
during the evening. Increasing south-southwest flow during the
early morning as a 40-knot low level jet shifts east. This
increases by Monday evening to a 50-knot jet. This flow supplies
plenty of moisture with PW values of 1.5 to 1.7 inches. Cross
sections show a deep moisture layer most of the day. Sufficient
confidence for chance pops after midnight early Monday and
likely pops during the day Monday. Convective parameters are
marginal at best, but enough chance to mention scattered or
widely scattered storms.
Cold front crosses the region Monday night between 00Z and 06Z.
Drier air moves in during the overnight and should bring clearing
skies.
Tuesday...
Upper shortwave crosses early Tuesday with cooling temps at 500 mb
during the day. This should generate diurnal cumulus, but
insufficient for showers. Mixing to 800 mb with temps 4-6C...that
should support max temps in the 70s.
Wednesday-Thursday...
The next shortwave sweeps east from the Midwest Wednesday with
increasing upper divergence/venting during the afternoon and night.
Low confidence on timing of the onset, but expect a chance of
showers starting either Wednesday afternoon or at night.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Friday Night/...
03z TAF Update...Moderate confidence through 06Z due to
convection and then high confidence thereafter.
SW winds diminish this evening.
VFR conditions should persist most areas with localized
MVFR/IFR in scattered showers/tstms. The tstms should weaken as
they reach RI and the eastern MA coast 04-06z. Main concern
continues to be strong wind gusts (40kt) with the tstms,
especially those moving across NE MA.
Also expecting patchy fog near South Coast, Cape, and Islands
with local MVFR/IFR visibilities, which rapidly improve after
sunrise Fri.
Winds shift to W and then NW during day Fri. VFR outside of
isolated showers/storm mainly focused south of Mass Pike thru
mid afternoon. VFR Fri night.
KBOS TAF...High confidence, including timing of VCTS later
tonight.
KBDL TAF...High confidence, including timing of VCTS tonight.
Outlook /Saturday through Tuesday/... Moderate confidence.
Saturday-Sunday...
VFR. Diminishing northeast gradient winds Saturday, becoming
variable in the afternoon. Light wind Sunday with developing sea
breezes along the coasts.
Monday...
General MVFR cigs/vsbys in rain and fog with areas of IFR possible.
South-southwest winds with 2000-foot winds reaching 40-50 knots
along the coastal plain...potential for low level wind shear.
Tuesday...
VFR with west winds gusting to 20 knots.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Friday Night/... High confidence.
SW winds diminish this evening. Seas build on outer waters S
and E of Cape Cod where we will issue a Small Craft Advisory
through Fri.
Cold front drops south across waters Fri, and may trigger an
isolated shower or storm through mid afternoon. More
importantly, winds shift to W during the morning and then NW in
the afternoon. May see brief 20-25kt gusts but not confident
enough to expand SCA.
Outlook /Saturday through Tuesday/... Moderate confidence.
Saturday-Sunday...
High pressure moves over the waters Saturday and off to the
southeast Sunday. Expect northeast winds Saturday trending to light
later in the day and then become southerly on Sunday. Seas less
than 5 feet. No headlines expected.
Sunday night-Monday...
Weather system sweeps east from the Great Lakes. South-southwest
winds will increase during Monday. Winds at 2000 feet will increase
with speeds of 40-50 knots by afternoon. This may bring a period of
20-25 knot speeds by Monday afternoon. The steady southwest wind may
bump seas to around 5 feet on the outer waters and exposed waters
such as Rhode Island Sound. Visibility will be low at times in rain
and fog. A cold front moves through Monday night, bringing a wind
shift from the west and lighter wind.
Tuesday...
West-northwest winds will bring drier air. Expect speeds less than
20 knots, with seas less than 5 feet.
&&
.CLIMATE...
Records were broken in Boston, Providence, and Hartford today
and tied at Worcester. Refer to the latest Record Event Reports
which were issued earlier.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ002>004.
MA...Air Quality Alert until 11 PM EDT this evening for MAZ004>007-
010>023-026.
RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>008.
MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ235-254>256.
&&
$$
SYNOPSIS...WTB/JWD
NEAR TERM...JWD/Thompson
SHORT TERM...JWD
LONG TERM...WTB
AVIATION...WTB/JWD/Thompson
MARINE...WTB/JWD
CLIMATE...
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1203 AM EDT Fri May 19 2017
.AVIATION...
A well, organized trough axis is extending through southwestern
Ontario into far southeastern Michigan as of 4Z. This surface
feature is the delineator of the main surface cold front. Model data
continues to advertise the surface cold front will push from north
to south tonight, clearing the Michigan and Ohio stateline between
09-12Z this morning. Very strong signal exists for stratus
development in the cold air advection. Satellite trends have been
very bullish thus far, with extensive stratus/stratocumulus in place
over central and northern Lower Michigan. Stratus will be slow to
scatter out, possibly holding on as late as 20Z.
//DTW THRESHOLD PROBABILITIES...
* High for ceilings below 5kft late tonight through Friday morning.
&&
.PREV DISCUSSION...
Issued at 301 PM EDT Thu May 18 2017
DISCUSSION...
Wind advisory continues through 8 PM.
Center of upper level PV anomaly and surface low now due north of
Lake Huron over Ontario late this afternoon. Excellent boundary layer
mixing today has yielding wind gusts around 40 knots/45+ mph, along
with lowering dew pts into the 50s, as dry mid level air is tapped.
It remains highly doubtful any activity (outside of an isolated
shower) will be touched off across southeast Michigan except right
near the Michigan/Ohio border as the cold front tracks through early
this evening. Even with lower dew pts, SBCAPES still around 1500 J/kg
near the southern Michigan border, with visible satellite showing
decent CU field over northeast Indiana, so a low chance of thunderstorms
(slight chance severe) remains until the cold front pushes south of
the state. The 12z HIRESW-ARW has come in dry, as well as the muted
response and south of the border solution offered up by the 17z HRRR
which seems reasonable.
Good low level cold advection Tonight, helped out by northerly
marine push off Lake Huron, as 925 mb temps lower to around zero over
the northern thumb region by 12z Friday. This amount of cold air
over the warmer nearshore waters/Saginaw Bay could possibly trigger a
few sprinkles, but inversion heights are very low, and likely just
looking at low stratus deck which will gradually mix out during the
daytime hours. Significant north-south temp gradient advertised over
southeast Michigan, with 925 mb temps around 10 C supporting lower
60s south of M-59 to lower 50s degrees across northern Thumb region.
Large upper level low over Four Corners region/Central Rockies to
lift northeast, with max 6 hr height fall center tracking
through/near Minneapolis Saturday Evening. The question is how long
will the large high over Ontario/Southern Quebec hold, before the
moisture advection/transport overtakes the Central Great Lakes. It is
possible showers and thunderstorms arrive during the day on
Saturday, especially west of U.S. 23, but more than likely the bulk
of the activity will hold off until Saturday night when the low level
jet and triple point/occlusion lifts through the State.
The area will remain in a large upper level trough through much of
the extended forecast period. This brings continued chances of
unsettled weather and cooler temps to the area. A cold front will
push across on Sunday as the low moves towards the Hudson Bay. Rain
is expected to diminish by Sunday evening as drier conditions move
in. Cooler air filtering behind the front will keep temps on the
cooler side with highs in the 60s for most of the week.
MARINE...
Southwest flow ahead of an approaching cold front will continue to
provide strong gusts over the land through early evening. Gusts up
to 35 knots will persist along the immediate shorelines, and also
over Saginaw Bay where winds have been locally higher this afternoon
due to funneling effects. Small Craft Advisories remain in effect
for most nearshore waters, with the exception of Saginaw Bay where a
Gale Warning continues until 800 PM. There is also a small chance
for thunderstorms to develop in advance of the cold front through
early evening, with best potential over Western Lake Erie.
Winds will turn north as the front drops south through the region
this evening and tonight. Winds will initially be gusty, especially
over Lake Huron, then decrease in speed by early Friday morning. The
long duration of north winds into Friday will allow wave heights to
build in excess of 4 feet over southern Lake Huron. Hence, Small
Craft Advisories for the Lake Huron nearshore waters will continue
into Friday.
HYDROLOGY...
Isolated thunderstorms may develop late this afternoon/early this
evening toward the Ohio Border. Storms will have the potential to
produce brief periods of heavy rainfall if they do develop. The fast
motion of the storms will limit rainfall, however, limiting totals to
one- quarter of an inch or less.
Low pressure lifting across the Upper Midwest will spread showers
and thunderstorms into the area late Saturday through Sunday. Total
rainfall looks to average in the 0.3 to 0.6 range, with higher
totals expected in places where thunderstorms occur.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-422-
441>443.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....DRK
DISCUSSION...SF/SS
MARINE.......HLO
HYDROLOGY....HLO
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
636 PM CDT Thu May 18 2017
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 255 PM CDT Thu May 18 2017
Cold front extended from lower MI to central IL and then to low
pressure situated in the se corner of CO. Classic severe weather
set-up in the Plains with a dry line in west TX with temperatures
around 90 and dewpoints in the teens to the west, and readings
near 90 with dewpoints near 70 east of the dry line. GOES-16
showed supercells rapidly developing west of Wichita Falls and
Lawton moving northeast. In the meantime, a snowstorm was
occurringin CO and WY.
In the dvn cwa, northerly winds were bringing clouds and cooler
temperatures to our northern cwa while it was milder in the south
with a west wind, and plenty of sunshine. 2 pm temperatures
ranged from 61 at Independence to 82 at Macomb.
&&
.SHORT TERM...(This Evening through Friday)
ISSUED AT 255 PM CDT Thu May 18 2017
Forecast focus on showers and thunderstorms returning.
Numerous tornadic supercells will be firing across the central/southern
Plains and into western MO through this evening. These will
eventually congeal into clusters/lines and then spread towards the
dvn cwa. The ESRL HRRR and NAMNEST indicate these storms to gradually
weaken and stratify out as they get into our sw cwa well after
midnight. However, an isolated elevated severe hailer (around 1 inch)
is possible in our far south where SPC has a marginal risk. There
is at least moderate shear but instability is minimal. These
showers and embedded storms will then continue spreading northeast
over the remainder of the cwa Friday morning. On Friday afternoon,
any scattered showers and isolated storms should gradually
diminish and many areas may end up dry, as the forcing weakens.
Rainfall amounts averaging around 1/2 inch is expected.
Lows tonight will range from the lower 40s along Highway 20 to the
mid 50s in extreme northeast MO. Highs on Friday should range from
the lower 50s along Highway 20 to the mid 60s in extreme northeast MO.
.LONG TERM...(Friday Night through Thursday)
ISSUED AT 255 PM CDT Thu May 18 2017
Complex long term scenario, with a slight chance of severe
weather and decent rainfall early this weekend, along with a drop
in temperatures expected by next week.
Friday night into Saturday...Model consensus is in good agreement of
showers and thunderstorms across the entire CWA beginning during the
Friday night period. Modest instability and shear will also be
present, which may help support hail in the stronger storms.
Compared to previous runs, all models seem to be converging on the
track of the surface low, with a general track from southern Iowa to
northeast Iowa during the day. Handling of the warm sector, however,
is still subpar likely due to forecast precipitation coverage. The
GFS continues to favor a more northern intrusion of the warm sector
into our southeastern counties, while others such as the Canadian
keep it and associated precipitation south into central Illinois.
The Storm Prediction Center has placed our counties along and
east of the Mississippi in a marginal risk of severe weather at
this time, and will therefore continue to monitor this low
confidence situation.
Saturday night through Monday afternoon...Showers and thunderstorms
will exit the region Saturday night, giving way to a mix of clouds
and sunshine for Sunday and much of Monday as high pressure builds
across the central Great Plains and lower Mississippi Valley.
Temperatures for Sunday will be below normal as cooler air advects
behind the departing low, with highs expected to climb into the
upper 60s. By Monday we will return to normal as highs climb into
the lower 70s.
Monday night on...Our next system will impact the CWA Monday night,
with showers and thunderstorms expected through the day Tuesday.
It`s too early to gage if severe weather will be possible, but at
this time forecast instability is low across the region.
Further out, most models suggest drier weather making its way
into the region by Wednesday and continuing through at least
Thursday evening. The GFS is the only outlier with an upper level
shortwave moving into the area on Thursday. Look for temperatures
to average below to near normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
ISSUED AT 637 PM CDT Thu May 18 2017
A reinforcing cold front making its way southeast through eastern
Iowa was providing a wind shift to more northerly surface winds
and a trailing stratocu deck likely to remain just above MVFR
thresholds this evening. Winds will veer to the northeast and
strengthen overnight as a storm system strengthens in the plains.
Elevated showers and thunderstorms are expected late tonight and early
Friday morning, which will dissipate to showers by mid morning.
This is expected to be followed by lowering ceilings and possible
light fog as cooler air moves in from the east-northeast during
the day. Will keep conditions MVFR for now, thinking the models
may be too pessimistic with their widespread sub 1000 ft, IFR,
ceilings over the region in the afternoon.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Speck
AVIATION...Sheets
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
731 PM CDT Thu May 18 2017
.AVIATION...
00 UTC TAFs
Concerns---Timing of convection and convective cessation. Any
storms that occur at or near TAF sites will have the ability to
produce frequent lightning, large hail and strong winds in excess
of 30-40 knots. MVFR, possibly IFR ceilings may return tonight
with additional chances for convection on Friday afternoon.
Otherwise, breezy southerly non-thunderstorm winds will likely
continue through the entire TAF period.
For the DFW Metroplex TAFs---Convection has been slow to develop
across North Texas this afternoon and evening mainly as a result
of a stout capping inversion and the lack of large scale ascent.
The latest 00 UTC FWD RAOB has indicated that capping has weakened
and while this has occurred, large scale ascent has been lacking.
As a corridor of better ascent slowly overspreads from the
northwest and low level wind flow intensifies, it`s possible that
this convection slowly moves towards the east. At this time, think
that most operational guidance has been a little overdone in its
QPF/simulated refelctivity output. That being said, the latest
experimental HRRR and to some degree the latest TTU WRF appear to
offer plausible solutions. Strengthening low level flow of around
40 knots around 925mb may fuel the ongoing complex of storms
eastward towards the I-35 corridor through midnight. Right now,
confidence is a tad on the low side and so for now, I`ll simply go
with VCTS for a couple of hours between 0300-0500 UTC. If
activity out to the west becomes a bit more robust, amendments to
re-introduce TS may be necessary.
With the increasing wind field through 0300 UTC coupled with
subsidence beneath the anvil, the Metroplex terminals should
respond and gust upwards into the 30 to 35 knots.
Convective chances should subside through the overnight hours,
but we will need to keep tabs on any complexes that attempt to
develop to the west. MVFR stratus should flow northward towards
Metroplex terminals around 09 UTC, as a strong low level jet
persists. Some guidance hints at the potential for IFR ceilings,
but the strong winds at and just above the surface should largely
mitigate this threat. MVFR stratus below FL020 will likely
continue through a majority of the day on Friday as the boundary
layer remains moist. Breezy southerly winds with gusts up to near
25-30 knots will also be possible. There may be an outside chance
for some showers just before midday, but confidence isn`t very
high during this time. For now, will only introduce VCSH until 21
UTC, but we will monitor the potential for inclusion of TS in
later issuances.
For the Waco TAF site---Breezy southerly winds will continue at
the Waco TAF site as the surface pressure gradient remains tight.
Similar to the Metroplex, convective chances at Waco will hinge
largely on the areal coverage of storms to the west. At this time,
will keep VCTS for a few hours this evening and monitor trends.
MVFR stratus should return just after midnight and continue
through the afternoon. There`s a low threat for some IFR ceilings,
but at this time, think that the breezy winds down near the
surface may keep the duration very low.
24-Bain
&&
.PREV DISCUSSION... /ISSUED 358 PM CDT Thu May 18 2017/
Afternoon visible satellite imagery shows an extensive cumulus
field across North Texas with ongoing severe thunderstorms across
western Oklahoma and far northwest Texas. There have been several
convective attempts farther south across our western counties, but
so far the cap has held. The cu field is showing some signs of
becoming more vertical though and with stronger forcing for ascent
still expected, we should see scattered severe thunderstorms
develop through the early evening. Short term model guidance is
still in fairly good agreement with scattered deep convection
developing from near Wichita Falls as far south as Killeen. The
atmosphere remains strongly unstable with surface based CAPE near
4000 J/kg. Very steep lapse rates and sufficient deep layer wind
shear will support supercell storms capable of producing very
large hail and damaging winds along with a few tornadoes.
Organized clusters of thunderstorms should also develop mature
cold pools given the amount of dry air aloft which would enhance
the potential for damaging winds.
Coverage of thunderstorms still remains the main uncertainty given
the cap strength. Initial development across the western counties
should be scattered (30-40%) and could occur on any one of a
number of localized areas of convergence. One of these extends
south of the ongoing supercell thunderstorms west of Wichita
Falls. Thunderstorms may tend to increase in coverage as they move
east later this evening as the cap continues to erode. After dark,
the main area of forcing will begin to shift off to the northeast
and areas along and north of I-20 may have the better chance for
continued thunderstorms. Long story short, there is the potential
for significant severe weather across parts of North Texas, but
not all areas are expected to be impacted.
Convection should weaken during the overnight hours, although the
front/dryline will remain across southwest Texas. Another strong
vort max will rotate around the main upper low over New Mexico.
This stronger forcing for ascent should help ignite a new round of
showers and thunderstorms, most of which will remain to the west
of the area. This convection will weaken during the early morning
hours on Friday. By Friday afternoon, we should remain fairly
unstable and a new round of convection is expected to develop
along the front/dryline to the northwest of the area. The
potential will remain for severe weather during this time. As the
main upper low finally ejects out into the Plains, a cold front
will slide southward and rain/storm chances will increase across
all of North Texas Friday night into Saturday morning. There will
be a threat for severe weather during this time, with damaging
winds being the main threat. In addition, there could be some
locally heavy rainfall.
The cold front should be south of the area on Saturday, although
rain and thunderstorm chances will continue, especially south of
I-20. We`ll maintain rather high PoPs south of I-20 through the
day Saturday with things tapering off by Sunday. The weather
pattern will remain active through next week with additional
thunderstorm chances Monday through Tuesday night.
Dunn
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 73 87 70 80 62 / 60 20 80 40 30
Waco 74 88 72 83 63 / 30 20 50 60 60
Paris 70 82 69 78 59 / 40 10 60 50 30
Denton 72 83 67 78 58 / 60 20 80 40 20
McKinney 71 84 69 79 60 / 50 20 80 40 30
Dallas 74 87 72 81 64 / 50 20 80 50 40
Terrell 73 87 71 81 62 / 30 10 60 50 40
Corsicana 74 89 72 83 64 / 20 10 40 60 60
Temple 74 87 72 84 64 / 30 20 40 60 60
Mineral Wells 70 84 65 77 58 / 60 30 80 40 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
24/24
Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CDT Thu May 18 2017
.UPDATE...
Issued at 905 PM CDT Thu May 18 2017
A couple of narrow bands of convection have lingered in far
eastern Illinois this evening, in the vicinity of a stalled
frontal boundary. There has been a general weakening trend over
the last couple of hours. Those storms should dissipate over the
next hour or so, with dry conditions for several hours and
possibly much of the rest of the night. The HRRR is indicating
some redevelopment near the front by 09z, mainly between I-70 and
I-72. A stronger wave of storms is projected to arrive from the
west toward 12z, with a few of those storms possibly strong to
severe. Bulk shear and low level helicity north of the warm front
appear sufficient for a few strong updrafts, with some strong
downburst winds possible as the line advances to the ENE after
sunrise tomorrow morning.
Have adjusted the PoP, Weather and Sky grids down in coverage
over the next 3-5 hours, with gradual increasing PoPs from west to
east late tonight.
A wide range of temps will exist across central Illinois for low
temps, due to the presence of the front. Lows will remain in the
low to mid 60s south of the front, with low 50s from Galesburg to
Lacon and mid-upper 50s in between.
Updated forecast info is already available.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 300 PM CDT Thu May 18 2017
Showers and a few storms beginning to increase again across the
Ohio Valley this afternoon, back into southeast Missouri. Most of
the forecast area only seeing scattered clouds at the moment, with
a cold front edging into the northwest part of the CWA.
Temperatures have reached the mid-upper 80s over a good part of
the CWA except northwest of the Illinois River near the front,
where Galesburg was still holding in the upper 70s.
The front will be settling to around the I-72 corridor by mid to
late evening and I-70 overnight, with little movement due to the
near parallel flow aloft. Most of the short-range models maintain
some isolated showers or storms south of it through the evening.
The main threat of rain will be spreading in from the southwest
later in the night, as the large upper low over Utah and Colorado
digs southward and sends energy northeast out of the Texas
panhandle.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 300 PM CDT Thu May 18 2017
The front doesn`t make a lot of northward progress during the day
on Friday, but will surge northward Friday night as a shortwave
continues to push northeast. A rather large temperature gradient
can be expected, with highs ranging from the 60s from Havana-
Bloomington northward to around 80 degrees south of I-70. Plenty
of CAPE will be available south of the front, generally at least
2000 J/kg with even higher numbers indicated by the NAM, although
this will not be in an area of favorable shear. This should be
enough for some strong to severe storms, primarily over areas from
about I-72 southward.
Some tapering of the rain is expected during the evening, before
another widespread rainfall accompanies the approach of the
surface low as the upper system moves into the Plains. This will
usher in an extended period of precipitable water values of around
1.5 inches, which will persist until the low lifts northwest of
Illinois Saturday evening. A fairly widespread 1-2 inches of rain
appears likely over the forecast area, with some heavier amounts
in the stronger storms.
Once this system exits early Sunday, an extended period of cooler
conditions is expected for the upcoming week. As the upper low
moves north of the Great Lakes, a lobe of energy will drop
southward and form a deep trough over the Plains, slowly pushing
eastward across the Mississippi valley in the Tuesday night to
Wednesday time frame. Some model differences in the longer range
with this feature, with the ECMWF slower and further south as an
upper low cuts off. However, the precipitation that occurs should
mainly be periodic showers, with thunder chances fairly small.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 703 PM CDT Thu May 18 2017
Ongoing convection associated with a stalled frontal boundary
are expected to remain clear of the TAF sites for much of the
first 12 hours of this TAF period. A wave of storms is projected
to arrive near PIA and SPI between 11z-13z. The line of storms
will progress eastward across the area tomorrow morning, but with
scattered storms possible through mid-day. There should be a break
in the rain/storms for at least the first half of the afternoon,
before another line of storms progresses eastward across central
IL starting near the end of this TAF period.
Forecast soundings are showing a stratus deck developing after the
line of storms moves through tomorrow morning, with low MVFR and
IFR conditions expected. Conditions should improve to MVFR
tomorrow afternoon, with VFR conditions possible at times.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Indianapolis IN
1157 PM EDT Thu May 18 2017
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 240 PM EDT Thu May 18 2017
A frontal system will interact with instability and increasing
moisture and result in showers and thunderstorm chances through
Sunday. The best chances will be Saturday night and Sunday, when a
cold front will be moving across central Indiana from west to east.
High pressure will bring dry weather to the area by Sunday night,
but then there will be more thunderstorm chances starting overnight
Monday night as an upper system tracks southeast towards the lower
Great Lakes and Ohio Valley.
Above normal temperatures will persist through the weekend with
cooler temperatures in store next week.
&&
.NEAR TERM /Overnight/...
Issued at 947 PM EDT Thu May 18 2017
Radar shows Thunderstorms slowly weakening across the two
boundaries in central Indiana. The storms across the southern
parts of the forecast area have almost dissipated
completely...while the northern line continues to slowly wane and
move east. Expect this trend to continue as daytime heating
continues to be lost and storms continue to slide east along the
boundary to the north. For now GOESR show nearly steady state
cloudy top temps...but for now not expecting this trend to
continue with loss of instability.
THus will trend pops lower and progress storms east-southeast over
the next few hours. The surface boundary is expected to sink
farther south across Central Indiana...and as dynamics approach
the area toward daybreak...the HRRR suggests new development along
and near the boundary. Thus will return to ramping pops upward
after 09Z. Used a blend on Temps...and feel that cooling on the
northside of the boundary may be overdone. Points on the warm side
of the front should see lows close to persistence.
&&
.SHORT TERM.../Friday through Sunday/
Issued at 240 PM EDT Thu May 18 2017
The main focus for the short term will be on timing and coverage of
showers and thunderstorms through Sunday.
Models general agree on synoptic pattern and features. So, will
accept the blend.
An upper low over southern Colorado and northern New Mexico Friday
morning will makes it way north and northeastward to northern
Minnesota on Sunday as a ridge builds over the eastern states.
Meanwhile, a cold front will start off over southern Indiana on
Friday but should return north as a warm front Friday night and
Saturday. Finally, a cold front will sweep through the area
overnight Saturday night into Sunday.
Models have an upper wave ejected from the upper low move through
the area Friday afternoon from southwest to northeast. Thus, after
small morning pops along and south of the front, will keep the good
chance afternoon pops from the blend.
As the upper waves moves northeast of the area and sun sets, should
see a lull in convection Friday evening. However, the upper ridge
will move into eastern Indiana and western Ohio Friday overnight and
into Saturday and a modest low level jet will set up over west
central Indiana. This warrants higher pops overnight Friday night
into Saturday. The best combination of moisture and forcing will be
Saturday night and Sunday morning as the cold front moves in from
the west. In addition, upper jet dynamics will become a factor as
the area will be in the right rear quadrant of a 90 plus know 250
millibar jet. The activity will then be ending from west to east
behind the front Sunday afternoon.
With the front moving through, temperatures should only reach normal
highs in the lower and mid 70s per the blend. Prior to that, With
the cold front moving through tonight expected to stall over south
central Indiana, looks like there will be a decent temperature
gradient on Friday, with near normal highs in the lower 70s north of
the front and above normal highs in the upper 70s to around 80 south
of the front. With the front to the north, prefer above normal highs
in the upper 70s and lower 80s.
Plenty of instability for thunderstorms through the short term per
all the models. Also, Marginal Risks for severe storms from the
Storm Prediction Center look reasonable through Day3.
&&
.LONG TERM (Sunday night through Thursday)...
Issued at 153 PM EDT Thu May 18 2017
The initialization from Region will be used with rather high
confidence.
The deterministic models have differences, but arrive at similar
temperature and precipitation predictions. This builds confidence
in today`s forecast since no matter which model is right, the end
result should be about the same.
Possible temperature errors are 1-3 degrees, and possible POP
errors around 10 percent.
&&
.AVIATION /Discussion for the 190600Z TAFs/...
Issued at 1159 PM EDT Thu May 18 2017
VFR Conditions will continue through the overnight. Isolated
showers/storms continue to dissipate and weaken as the frontal
boundary sags southward across the forecast area. May include a
brief mention of VCTS at some of the taf sites based upon radar
trends near issuance time to account for this. A decreasing trend
is still expected.
Some MVFR Conditions are possible on Friday by mid morning as a
short wave is expected to push across Central Indiana. Models
suggest favorable forcing for precip and MVFR CIGS are expected as
the forcing passes and the surface boundaries remain in the area.
Time heights show plentiful lower level moisture available. Thus
have included a prevailing precipitation event. As forcing
departs after 00Z Saturday...a return to VFR conditions is
expected.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...Puma
SHORT TERM...MK
LONG TERM....JK
AVIATION...JP
Area Forecast Discussion
National Weather Service Jackson MS
942 PM CDT Thu May 18 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
The showers and thunderstorms that moved through early this
evening have dissipated across our region, and conditions are
expected to stay dry overnight. However, with still an abundant
amount of moisture left in the atmosphere, some patchy fog can`t
be ruled out before first light. Spots east of I-55 will be the
main area for developing fog, which shouldn`t come as no surprise
since this was the main sector that had isolated showers/storms
earlier when that tongue of moisture seeped in from the Gulf.
Friday will have another build up of showers and thunderstorms as
the day progresses, but unlike today the Delta will not be immune
to staying dry. A shift of higher values of preciptable water in
the HRRR suggests values above 1.50 inches in the Delta and SE
Mississippi. Expect these two regions to be the areas to watch on
radar Friday afternoon as isolated pop-up storms come in from the
south. /12/
Prior discussion below:
Tonight through Friday,
A warmer than normal and moist weather pattern will persist over the
ArkLaMiss tonight through Friday as a mid level ridge center remains
anchored near the southern Atlantic Coast region. The resulting
southerly flow will continue to send copious amounts of low level
moisture into the forecast area making for rather humid conditions
and considerable late night and morning low clouds, including a
chance for fog mainly in the Pine Belt region where winds will be
lighter. As was the case today, diurnal convective precipitation
will develop Friday given plenty of instability and sufficient deep
layer moisture, but relative warmth in the mid levels of the
atmosphere associated with ridge should help to limit thunder
potential. Overall, the potential for any strong to severe storms is
very low through tomorrow. High temperatures will once again
approach 90 F over much of the area. /EC/
Friday night through Wednesday:
On Friday night an active pattern will continue through the Plains
as we will be wedged from strong ridging centered over the Southeast
Atlantic coast. Rain chances will continue as we push into the
weekend. As we move into Saturday instability will be increasing
during the day as a wave pushes into the region from the plains.
We will be looking at vertical totals in the upper 20s, lapse rate
around 7c, ML Capes of 2000 Plus, and some deep layer shear of 20
to 40 knots. The flow will be on the weak side in general
according to model soundings. So with this in mind will follow
SPC`s marginal risk across the west half with the risk of damaging
winds, and some hail up to quarter size. Rain chances will be on
the likely side through the weekend. The front is expected to come
through on Sunday into Sunday night. There could also be some
possible strong storms with the frontal passage, which will bear
watching on Sunday into Sunday night. The Euro and its ensembles
seem to hang to front up during this period, while the GFS and
Canadian as well as their ensembles seem to be more progressive as
the upper trough energy lifts into the Upper Mississippi Valley
then the Great Lakes by early next week. As we move into early
next week we will have a zonal flow and will go to a more diurnal
convective pattern. Meanwhile another upper trough will be
rotating around the Mid Mississippi Valley to the southern plains
which will send a front toward the region. The upper trough axis
will rotate into the Mississippi Valley which will push another
front into the region for midweek. This system will send a 140
knot jet across north Mississippi. This system may trigger some
severe storms and will bear watching with deep layer shear of 40
to 50 knots. The Euro was farther south with the Closed Low./17/
&&
.AVIATION...
00Z TAF discussion:
Convection continues to wind down with lingering storms closest to
the GTR vicinity. VFR conditions will prevail until midnight with
MVFR/IFR ceilings moving in from the south after midnight. These
ceilings will begin rising after sunrise and be VFR by 19/18Z.
Convection will be somewhat less on Friday compared to today and
mainly confined to the GLH vicinity./26/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 71 89 70 87 / 9 24 8 58
Meridian 68 89 69 88 / 6 18 7 55
Vicksburg 71 89 72 89 / 11 30 9 55
Hattiesburg 69 88 68 87 / 9 26 7 59
Natchez 71 88 71 88 / 11 32 10 59
Greenville 72 88 72 87 / 3 33 10 48
Greenwood 72 88 71 87 / 4 22 9 51
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
12
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
854 PM EDT Thu May 18 2017
.UPDATE...
Issued at 854 PM EDT THU MAY 18 2017
The remainder of the evening looks to remain dry, before showers
and thunderstorms increase in coverage tonight ahead of a
shortwave impulse across lower Tennessee/northern Alabama. Deeper
moistening late tonight and Friday morning further support
development, although wind fields will remain rather lackluster.
Will also have to monitor the potential for fog through early
tonight, given crossover temperatures mainly in the mid-upper 60s,
before precipitation produces enough mixing to erode this concern.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 331 PM EDT THU MAY 18 2017
Convection has increased in coverage in the southern part of the
forecast area over the past hour, and is greater in coverage than
originally expected. Showers and thunderstorms continue to move
northeast. With that in mind have increased thunderstorm coverage
from isolated to scattered over the southeast part of the forecast
area for the remainder of the afternoon and into the early
evening, while continuing with the isolated coverage in the
northwest.
With the loss of daytime heating the convection should quickly die
off this evening. However, while there is considerable model
disagreement on redevelopment later tonight some of the latest
short range guidance including the HRRR is pointing towards
redevelopment in the southeast late tonight and towards dawn.
This seems to be related to a subtle short wave trough that will
move northeast towards the area late tonight. With this in mind
have decided to go with chance probability area wide late tonight,
with best chances in the southeast.
There is still considerable model disagreement with the extent of
convective development on Friday, though it looks like coverage
should once again be scattered, but with more of the area
affected than this afternoon. Will continue with generally high
chance probabilties for showers and thunderstorms area wide on
Friday.
With more clouds and precipitation tonight through Friday night
there will be less of a diurnal temperature range with highs on
Friday a little lower than today.
.LONG TERM...(Saturday through Thursday)
Issued at 354 PM EDT THU MAY 18 2017
A longwave trough pattern will be centered around two upper level
lows as they move across the Northern Plains to start out the period
at 12Z Saturday. This pair of lows will combine into one system,
continuing its slow track to the northeast over the next couple of
days, reaching Minnesota by Sunday morning and Ontario by Monday
morning. This will push the longwave trough and lowering heights
eastward as well, impacting the Ohio Valley through the weekend. The
axis of this trough should pass across Kentucky Monday morning as it
deamplifies considerably. Models remain in fairly good agreement
during the day Monday and into Tuesday, developing another shortwave
that will drop south across the Northern Plains and Upper
Mississippi Valley during this time, then swing eastward towards the
Ohio Valley Tuesday night. Timing starts to diverge at this point as
both the GFS and ECMWF push this system across our region to end out
the forecast period. This will have an effect on when at to what
extent precip associated with this system impacts the region, so
relied on model blends to round out this portion of the forecast.
At the surface, a low pressure feature will be in place, shifting
northeast across the Central Plains and into the Mid/Upper
Mississippi Valley during the day Saturday. It will slowly track
northeast, reaching the Upper Great Lakes by Sunday morning, and
then into Ontario by Monday morning. A cold front will extend
southward from this low pressure center, sweeping eastward across
the Mississippi Valley Saturday night, then into the western Ohio
Valley during the day Sunday. The front is expected to pass eastward
across our CWA Sunday night, consistent with previous runs over the
last day or two, so confidence in timing is pretty high. That being
said, the low will be pulling so far north at this point, the
frontal boundary will begin to shear out a bit as it passes over the
region, so won`t be quite as strong. The frontal passage will
quickly pass off to our east during the day Monday, with high
pressure expected to move in across the region through the day
Tuesday. The secondary shortwave that develops late in the period
will also translate to another surface low developing to our
northeast, and ultimately a secondary frontal system that will move
across the region Tuesday night into Wednesday.
As for sensible weather, a warm front will be located just along and
to our north during the day Saturday, with warm moist unstable flow
into the region, producing scattered showers and thunderstorms
throughout the day and boosting temps back into the mid 80s. The
loss of heating overnight will allow many of these showers and
thunderstorms to dissipate briefly. However, the incoming cold
front will create enough lift to produce more scattered convection
moving eastward across the CWA late Sunday night. These showers and
thunderstorms will increase in coverage throughout the day Sunday as
the cold front continues to near. Still not expecting a whole lot in
the way of severe weather with this, though given the super
saturated nature of the soundings from the surface all the way
through the atmosphere, would be more concerned for heavy rainers
and excessive lightning.
Once the front passes over Sunday evening/night, llvl winds will
make a sharp turn to the NE and temperatures will quickly drop, with
substantial dry air moving in a few hours later. This will
effectively cut off convective activity and precip all together, so
did not include mention of thunder after 12Z Monday. Highs on Sunday
will be in the mid and upper 70s based on clouds and rain, but post
frontal highs will struggle to reach 70 degrees in some locations by
Monday afternoon. Another incoming cold front for Tuesday night will
help boost southerly flow and temps during the day Tuesday, but
will also lead to another round of showers and potential
thunderstorms Tuesday afternoon/Tuesday night. The frontal passage
Tuesday night will bring an end to the convection once again, as
well as allow for the return of a cooler airmass to round out the
forecast period. Highs Wednesday and Thursday will only be in the
upper 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 854 PM EDT THU MAY 18 2017
Mainly VFR conditions to prevail through Friday afternoon,
although shower and thunderstorm coverage will likely be greater
beginning tonight into early Friday. Have thus inserted VCTS for
all sites from tonight through Friday morning. SYM probably will
not see much activity until after daybreak Friday. Held off on
prevailing thunder mention at any given terminal based on the
pulse nature of these storms and thus their quick-lived nature.
May very well see a period of sub-VFR ceilings or visibilities
underneath any shower or storm, but this probability also remains
too low at this time to include mention. Will monitor the
potential for any fog development through this evening and early
tonight before incoming precipitation produces enough mixing to
erode this threat. Showers and thunderstorms will also be possible
later on Friday, but timing/placement remain uncertain depending
on how the morning`s activity plays out.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GUSEMAN
SHORT TERM...SBH
LONG TERM...JMW
AVIATION...GUSEMAN
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
920 PM CDT Thu May 18 2017
.UPDATE...
Issued at 918 PM CDT Thu May 18 2017
We continue to track convective evolution out to the west this
evening. A broken line of thunderstorms exists over eastern
KS/eastern OK from earlier convection across the central and
southern Plains. A few supercells also have developed ahead of
this broken line, mainly north of a surface warm front near the
Kansas City metro area.
Convective evolution remains a bit uncertain overnight, as many of
the CAMs had suggested an organized cold pool would have developed
by now. While there have certainly been some bowing structures at
times, it appears convection remains fairly disorganized at this
time. Nonetheless, an increase in a nocturnal low-level jet is
likely underway and should lead to continued thunderstorm
development/sustenance over portions of eastern KS and into
western MO. While forecast soundings suggest increasing nocturnal,
surfaced-based CIN with time over central and eastern MO, think
if storms are able to develop a cold pool we may still see some
strong/locally damaging wind gusts along with some locally severe
hail as the convection moves into central/eastern MO. Have updated
the forecast to reflect these latest trends.
KD
&&
.SHORT TERM... (Through Late Friday Afternoon)
Issued at 333 PM CDT Thu May 18 2017
Main concerns through tomorrow will be the potential for severe
thunderstorms.
Cold front has become quasi-stationary from near Kansas City to
Quincy to Chicago. To the south, there have been a few showers and
thunderstorms that have developed across southeast Missouri. There
is still potential for thunderstorms to develop farther north near I-
70 late this afternoon into the early evening hours according to the
latest runs of the CAMS. This falls in line with the RAP which
shows some weak surface moisture convergence south of the front in
the 2000-3000 J/kg MLCAPEs. There may be a few storms continue to
develop along the front into the early evening hours.
Focus for storms will increase later this evening and overnight
farther west where severe thunderstorms that are expected to develop
over the Central Plains will grow upscale into an MCS per the latest
runs of the HRRR and move east across the CWA between 08-14Z. There
will be the possibility for a few strong to severe thunderstorms
during this time with some large hail and damaging winds. This
complex will lift to the northeast by mid morning allowing for dry
time from mid morning until early afternoon. If the atmosphere can
recover from the morning convection, then a few severe thunderstorms
will be possible in the afternoon given MLCAPES between 1500-2000
J/kg and deep layer shear values 40+kts along and south of the warm
front. Main focus for severe storms in the afternoon would be along
the warm front.
Britt
.LONG TERM... (Friday Night through Next Thursday)
Issued at 333 PM CDT Thu May 18 2017
(Friday Night - Saturday Night)
Best chance of convection early in the period will be along/north of
the slowly retreating warm front. Some disagreement on how
widespread this activity will be with CAMs suggesting isolated-
scattered activity while global models seem a bit more bullish.
Regardless, favorable environment will exist for strong to severe
thunderstorms capable of producing large hail and damaging winds,
with a tornado threat for any storms that can travel along the warm
front.
Another round of storms then looks to move in from western Missouri
overnight Friday night. Straight-line winds look like the primary
threat with convection expected to be more linear by the time it
reaches our CWA. Could Some signs the quasi-linear convective system
will weaken as it heads toward the Mississippi River toward daybreak
as low-level moisture convergence and instability slowly abates.
Will have to also monitor the potential for flash flooding with this
round of activity. Thankfully, the ground has gotten a good week to
dry out so flash flood guidance is fairly high. Concern would be for
any areas that get hit fairly hard tonight through Friday afternoon
and then get hit again Friday night. Will continue to monitor this
potential, but for now will hold off on a flash flood watch and see
how the next ~24 hours evolves.
Uncertainty increases on Saturday with respect to convective trends.
There will likely be some ongoing convection on Saturday morning as
alluded to above. How the morning convection evolves will be
important regarding afternoon destabilization and severe potential.
Does look like more of a marginal setup however with quite a bit
uncertainty with the amount of destabilization. Higher chance for
strong/severe storms at the moment look east of the Mississippi
River where higher instability will likely reside. Do expect at
least another round of showers and storms regardless of severity to
form along/ahead of the cold front which will sweep through the bi-
state area.
(Sunday - Next Thursday)
Well-below normal temperatures continue to increase in likelihood in
the extended with a deep upper-level trough carving out across the
eastern two-thirds of the CONUS. Highs generally will range from the
mid 60s to low 70s each day with lows as cool as the mid to upper
40s. Best chance of rain, with a few thunderstorms possible,
continues to look like the Monday night through Tuesday timeframe
coincident with a closed midlevel circulation moving
southeastward into the mid-upper Mississippi Valley and eventually
the Ohio Valley.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 636 PM CDT Thu May 18 2017
Main TAF concern will be convective trends overnight into Friday.
While a few storms continue to linger over eastern MO early this
evening, think we will see a general lull in thunderstorms from
this evening into the early overnight hours. However, a line of
showers/storms should approach COU/UIN after 07Z, spreading into
the St. Louis metro sites after 08-09Z. These storms will bring
lowered vsbys in heavy rain along with locally gusty winds.
Showers and a few thunderstorms will likely persist into the day
on Friday, but confidence is fairly low on timing/coverage.
Outside of any showers/storms on Friday, UIN will reside on the
cool side of a warm front which will allow for some MVFR cigs to
work in from the north.
SPECIFICS FOR KSTL:
Main TAF concern will be convection early Friday morning. Think
convection may begin to develop near the terminal as early as
7-8Z, but think a more concentrated line of showers/storms is
likely to move through between 10-14Z Friday morning. Any storm
will likely bring vsbys into the MVFR/IFR range. After the round
of convection Friday morning, confidence decreases in convective
coverage for Friday afternoon/evening. For now, will keep VCTS out
of the forecast for the afternoon until trends are better
ascertained.
KD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Midland/Odessa TX
928 PM CDT Thu May 18 2017
.DISCUSSION...
Latest sfc analysis shows the dryline slowly retreating up thru
the lwr Trans Pecos, w/convection trying to develop along this
feature east of the area. However, hi-res models continuing to
show convection developing in the Permian Basin after 06Z. We`ve
let the RFW and HWW expire, and will do a quick update to remove
them from grids and products. We`ll also adjust other parameters
as necessary based on latest obs and forecast data. Updates out
shortly.
&&
.PREV DISCUSSION... /issued 617 PM CDT Thu May 18 2017/
DISCUSSION...
See 00z aviation discussion below.
AVIATION...
VFR conditions are expected for the next 24 hours. Winds will
weaken this evening and become variable. Winds will intensify out
of the west late Friday morning. There is a slight chance of
thunderstorms tonight for MAF and FST.
PREV DISCUSSION... /issued 240 PM CDT Thu May 18 2017/
DISCUSSION...
Another hot and windy afternoon underway as the dryline continues
eastward across the area. This boundary will waffle back and
forth over our region the couple of days bringing chances for
rain mainly for the eastern Permian Basin and Lower Trans Pecos.
Much of W TX and SE NM has not received appreciable rainfall in
over a month and fuels continue to dry. Thus the need for Red Flag
Warnings over a large portion of the CWA. Please see the Fire Wx
section below for more information.
An upper level trough over the Rockies will lift into the Plains in
the coming days. Height falls associated with this system will
pull the dryline back west tonight to near the I-20 corridor. A
shortwave will round the base of the trough overnight helping to
increase large scale lift. Thunderstorms are expected to develop
along the dryline after midnight and push east. Will follow the
HRRR closest with respect to the position of the dryline since it
did will Tuesday with a similar situation. Some of these storms
will have the potential to be severe given adequate shear and
steep lapse rates. Large hail and damaging winds will be the main
threat with these storms. The dryline will move east again Friday
with much of our area being the in dry air by afternoon.
A cold front will head south as the upper trough lifts into the
Plains Saturday. A few storms are possible along the boundary Friday
night into Saturday mainly over the eastern Permian Basin and Lower
Trans Pecos. Much cooler conditions are expected behind the front
with below normal temperatures lasting through the weekend.
We warm slightly early next week before yet another cold front makes
a run at the area on Tuesday. A few more storms are possible with
this front as well, but widespread precipitation is not looking
likely at this time.
FIRE WEATHER...
Fuel conditions are pretty primed across the area today with the ERC
at the 75th percentile across most of the PB and 90th across the
Trans Pecos. Meanwhile critical fire is largely occurring across the
area too with single digit RHs across much of the Trans Pecos. Winds
are mostly 15-25 mph resulting RFTI of 3-4. RFW will continue until
9 PM CDT/8 PM MDT. Thur fire wx will be a concern again, but winds
will probably be just a little less. 85h winds of 20-22kts may end
up in a narrow corridor from the Upper Trans Pecos into the ne PB,
RH will be no problem. As such most favored area for RF wx will be
GDP Mtns/Upper Trans Pecos, possibly Eddy Co.? However fuels across
the Trans Pecos including BBNP and SE NM are dry enough keeping Sig
Fire Potential at least moderate? For now will issue a fire wx watch
for the GDP Mtns for Fri, but could be expanded to included
Culberson Co, Eddy County plains, most of the Trans Pecos for tmw as
a fuel biased RF could be justified.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 68 91 58 78 / 30 20 20 20
Carlsbad 58 85 52 81 / 10 0 0 0
Dryden 72 94 67 81 / 10 10 30 40
Fort Stockton 66 92 61 81 / 10 10 10 20
Guadalupe Pass 57 76 52 76 / 10 0 0 0
Hobbs 55 83 50 78 / 10 0 10 10
Marfa 55 84 45 81 / 10 0 0 10
Midland Intl Airport 63 92 57 81 / 20 10 10 20
Odessa 65 90 57 80 / 10 10 10 10
Wink 58 89 55 82 / 10 0 10 10
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...Fire Weather Watch from Friday morning through Friday evening
for Guadalupe Mountains.
TX...Fire Weather Watch from Friday morning through Friday evening
for Guadalupe Mountains.
&&
$$
80/44
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
911 PM CDT Thu May 18 2017
.UPDATE...
9PM CDT GOES IR imagery showed clear skies over the Midsouth, with
cirrus approaching from southern plains storms. Temperatures
prevailed in the lower 80s, expect over northeast MS, where
mid/upper 70s prevailed in a more humid airmass.
For the overnight last few runs of the HRRR and the 18Z/00Z NAM
models show little to no rain over the Midsouth. HRRR does hint at
some storms reaching northeast AR toward 7 AM, a southerly
extension of a storm complex lifting across MO.
Forecast was recently updated with a reduction in first period
rain chances.
PWB
&&
.PREV DISCUSSION... /issued 639 PM CDT Thu May 18 2017/
UPDATE...
Updated to add 00Z Aviation Discussion.
PREV DISCUSSION... /issued 338 PM CDT Thu May 18 2017/
DISCUSSION...
Current KNQA radar shows two areas of shower and thunderstorms
occurring across the Mid-South. The first being Northeast Arkansas
and the second being Northeast Mississippi. Expect this activity
to die out around sunset. Expect the rest of the evening to be
tranquil. Latest HRRR and NSSL WRF-ARW models show convection that
is currently developing across Oklahoma to begin approaching the
Eastern Arkansas around or shortly after midnight. Even the 3 KM
NAM is indicating that this could happen. Although this model
shows the line of convection dying as it pushes into the CWA. The
other two models indicate the line may hold together to at least
the Mississippi River. A lot will depend on the strength of the
line as it pushes across Arkansas as the upper ridge remains
fairly strong across the Mid-South. Will go ahead and bump up POPS
to likelys across Randolph and Lawrence Counties after midnight.
Will also have 40-50 POPS for the rest of Eastern Arkansas and the
Missouri Bootheel. Elsewhere, expect stratus to invade the area
around sunrise.
Whatever convection remains after sunrise will diminish during the
morning hours. Redevelopment will begin to occur by the early
afternoon hours due to diurnal heating. Any thunderstorms that do
develop on Friday will be very isolated to scattered in nature.
Otherwise, expect another warm day across the Mid-South with highs
in the upper 80s for the most part.
Diurnal convection will quickly dissipate during the evening
hours. Then all eyes will turn toward another possible line of
thunderstorms that will be moving across Arkansas that could bring
chances for showers and thunderstorms to Eastern Arkansas after
midnight Friday Night into Saturday morning.
By Saturday afternoon, expect numerous showers and thunderstorms
to be developing across the Mid-South ahead of a cold front.
Chances for convection will continue into Saturday Night into
Sunday as the cold front pushes through the CWA.
As for severe weather chances, can`t rule out strong to severe
storms occurring with the convection after midnight tonight across
portions of Eastern Arkansas or late Friday Night into Saturday
Morning. By Saturday afternoon through the rest of the weekend,
chances for strong to severe storms will occur across the entire
Mid-South ahead of the cold front.
Another cold front will move through the Mid-South on Tuesday and
will bring additional chances for showers and thunderstorms.
Wednesday will be a cool day across the Mid-South as an upper trof
is expected to move through the area. Expect light showers or
drizzle to occur with the trof. Highs will be in the upper 60s to
lower 70s.
KRM
&&
.AVIATION...
00Z TAFs
VFR conditions expected for much of tonight. MVFR ceilings are
anticipated to develop across the Lower Mississippi Valley and
into TAF sites between 10-12Z, with VFR conditions returning
towards Friday afternoon. VCTS possible at all sites mainly after
19/18Z. Light south winds will increase to 10-12 kts with a few
gusts to around 18 kts on Friday.
CJC
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1042 PM CDT Thu May 18 2017
.UPDATE...
Issued at 930 PM CDT Thu May 18 2017
Main concern tonight is the convective debris from storms that
fired over central Kansas during the afternoon is screaming north
and already working into the Twin Cities. This may keep us from
having frost issues, with lows tonight likely staying up a couple
degrees higher than we had, which would be enough to cut back on
the frost potential. At this point, we`ll keep the frost advisory
going, but confidence in the frost potential is decreasing.
For tomorrow, have slowed the northward push of the rain chances
as the 00z NAM has come in line with what most of the hi-res
models are showing with rain making up to about Mankato before dry
air takes over. Still looks like the big slug of rain comes up
after midnight Friday night, with Saturday morning looking rather
ugly with rain and temperatures in the 40s.
&&
.SHORT TERM...(This evening through Friday)
Issued at 253 PM CDT Thu May 18 2017
The low pressure system that moved through yesterday and last night,
is still departing to the east with widespread low clouds in
cyclonic circulation on the back side. The clouds have been eroding
across northern MN as high pressure across south central Canada
pushes in from the north. The eroding cloud trend will continue
through tonight, with slow dissipation of the clouds expected across
the area. The northerly flow is also bringing some pretty chilly air
down from Canada as 850H temps are now flirting with the freezing
mark.
So, the main concern is for frost tonight and the most susceptible
area is across northeast MN and northwest WI, and dipping into west
central WI and parts of central MN. Forecast lows indicate cold
enough temps for frost across these areas so went ahead and issued
a frost advisory. We will have to watch the wind though because
with the high well to our north, we may keep a slight breeze in our
area tonight, whereas farther north confidence is higher that
temperatures will dip.
For tomorrow, shortwave energy and low level warm air advection
will stream northward through Iowa into southern MN where rain is
likely, but with the stout high pressure in place and very dry air
from central MN and northward, the precip may not make it that far
north. Another cool day with temepratures in the 50s with that cool
airmass remaining in place.
.LONG TERM...(Friday night through Thursday)
Issued at 253 PM CDT Thu May 18 2017
Early afternoon water vapor imagery together Rap13 heights and winds
showed a powerful cyclone approaching the TX/OK panhandles. This
system will bring widespread rain across the entire region late
Friday night into Saturday. This system will be slow to move out, so
expect low clouds and a few showers to linger on Saturday. At this
point Monday looks dry, but overall expect a cooler more cloudy
forecast for the upcoming week with periodic chances for showers and
thunderstorms. The threat for severe weather is very low.
Saturday will be rainy as a large area of synoptic forcing
associated with the height falls from the Upper Level wave lead to
rising air, saturation, and rain. This is a large system so feel
very confident that most if not all locations have measurable
rainfall on Saturday. There are some slight timing differences
between the models, and for that reason used 3 hourly precip grids,
but increased the 12hr pop grid. Forecast soundings show little in
the way of instability except for far southeast MN and western WI,
so see this as mainly a light to moderate rain event. Total
accumulations of around 0.75 inches can be expected.
Wrap around could air advection will lead to cool temperatures on
Sunday, and forecast soundings show overcast skies with enough
instability atop the boundary layer to produce a few light rain
showers, so tried to time increased pops during the heating of the
day. Monday will be dry, but another northern stream shortwave will
rotate across the region and bring another round of showers.
Northerly flow will develop which should bring in some drier air and
upper level subsidence for the end of the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1045 PM CDT Thu May 18 2017
Only change made to existing TAFs was to remove prob30s for -SHRA
at MSP and RWF. 00z NAM has come in similar to what we are seeing
with the RAP and HRRR that dry air locally will keep any rain
Friday south of the MPX terminal. Main surge of rain Friday night
looks to be coming after 06z.
KMSP...we may see MVFR cigs and -RA moving in right at the tail
end of the TAF, but with the dry air expected to be in place, felt
better about taking a slower route to the arrival of both this far
out.
/OUTLOOK FOR KMSP/
Sat...MVFR/RA with IFR possible. Wind E at 10G20kt.
Sun...MVFR. Chc -shra. Wind WNW at 15G25kt.
Mon...VFR. Chc MVFR/-shra. Wind NW at 5-10kt.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Frost Advisory until 8 AM CDT Friday for WIZ014>016-025-027-028.
MN...Frost Advisory until 8 AM CDT Friday for MNZ043>045-052-053.
&&
$$
UPDATE...MPG
SHORT TERM...SPD
LONG TERM...JRB
AVIATION...MPG
Area Forecast Discussion...UPDATED
National Weather Service Omaha/Valley NE
726 PM CDT Thu May 18 2017
.UPDATE...
Issued at 725 PM CDT Thu May 18 2017
Showers and storms continue to expand northward early this
evening.
Added some counties in eastern Nebraska to the Flash Flood watch,
based on trends of storms to the south moving north. RAP model
suggests potential for rain amounts of 1.50 inches or more over
parts of southeast Nebraska by daybreak Friday morning.
&&
.SHORT TERM...(Tonight through Sunday)
Issued at 307 PM CDT Thu May 18 2017
...Near-term forecast concerns are heavy rainfall potential across
our southern counties tonight into Friday night...
A prominent mid-level cyclone was analyzed over the central
Rockies as of early afternoon with an associated vorticity lobe
and attending jet streak pivoting northeast across the central and
southern High Plains. At the surface, 19z analysis depicted an
area of low pressure over southwest KS with an accompanying
quasi-stationary front stretching northeast into northern MO.
The influence of the above-mentioned vorticity lobe and jet streak
on a strongly unstable air mass will yield widespread thunderstorm
development this afternoon within the warm sector across KS into
OK. Increasing moisture flux and warm advection along a
nocturnally strengthening LLJ will aid in the northward movement
of these storms into our area overnight. Isolated severe weather
in the form of marginally severe hail and locally strong wind
gusts is possible. However, the primary concern is flooding
rainfall given the antecedent near-saturated soil conditions. As a
result, we have issued a Flash Flood Watch from tonight into
Friday night for several of our counties in southeast NE.
We should see a break in the precipitation across much of the area
Friday morning as the stronger forcing associated with the lead
vorticity maximum lifts into the northern Plains. However, by
Friday afternoon into Friday night, the primary mid-level system
will shift east into the central Plains, contributing to
widespread showers and thunderstorms. Current indications are
that the system warm sector will remain to the south of the NE-KS
state line with the primary concern again being flooding
rainfall.
The deep-layer synoptic cyclone will develop northeast into the
upper Midwest on Saturday with drier conditions anticipated by
afternoon. By Sunday, northwest, downslope flow in the low levels
will support a warming trend with highs rising back into the 60s
areawide.
.LONG TERM...(Sunday night through Thursday)
Issued at 307 PM CDT Thu May 18 2017
Latest medium-range guidance is in reasonably good agreement in
suggesting that a substantial short-wave trough will track south
through the mid MO Valley in the Monday-Tuesday time frame,
supporting an increasing chance of showers and thunderstorms.
Thereafter, building mid-level heights will signal a drier pattern
along with gradually warming temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 654 PM CDT Thu May 18 2017
MVFR cigs and vsbys developing across the area through 06Z as
showers and thunderstorms spread north out of Kansas. Periods of
showers with cigs becoming IFR between 06Z and 12Z then continuing
through remainder of the forecast period as upper low tracks into
the western high plains.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch through late Friday night for NEZ050-051-
065>068-078-088>093.
IA...None.
&&
$$
UPDATE...Miller
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Fobert
Area Forecast Discussion
National Weather Service Pueblo CO
743 PM MDT Thu May 18 2017
.UPDATE...
Issued at 742 PM MDT Thu May 18 2017
Quick update to the forecast grids for latest obs data and radar
trends. Added isolated pops for the southern foothills and I-25
corridor through 11 pm tonight. Moore
&&
.SHORT TERM...(This evening through Friday)
Issued at 301 PM MDT Thu May 18 2017
This afternoon, thunderstorms have fired along a boundary in
southeast CO and are tracking northeastward. There will continue to
be the potential for a couple severe storms over sern CO into this
evening, with the main threat being large hail.
This evening, the highest chances for pcpn are expected to be found
over the central CO mtns, Teller county, Pikes Peak, and the
southwest mtns. These areas will see some additional accumulations
of snow. The latest run of the HRRR and the 18Z run of the NAM12
are showing decreasing chances of pcpn over El Paso county thru the
evening hours, except maybe ovr the Monument Hill area where there
could be a couple or a few inches of additional snow accumulation.
After midnight, the HRRR and NAM12 show a significant decrease in
pcpn chances across all of southeast and south central CO, with only
some isolated showers. The GFS continues to show a little more pcpn
than the other models, showing continued snowfall in the central
mtns thru the night, and some light snow accumulations over Teller
county and Pikes Peak, with some light showers over portions of the
southeast plains, increasing toward 12Z. The NAM is a bit farther
south with the upper low center Fri morning than the GFS. Both the
NAM and the GFS show widespread pcpn moving into southeast CO after
12Z, with the GFS being wetter and more widespread than the NAM. At
this time, it looks like there could be several inches of snow over
the southern Sangre de Cristo mtns beginning Fri morning and thru
the day, so will issue a Winter Weather Advisory. It is also
possible that the southern I-25 corridor counties could see several
inches of snow in the morning hours on Fri, mainly over Huerfano and
western Las Animas counties and especially west of the Interstate,
as temps are expected to be cold enough for a short period, but
impact will probably be low as the roads will probably just be
slushy or wet.
One other worry is the potential for low temps tonight around
freezing. Have decided to issue a Freeze Warning for northern El
Paso county, and a Frost Advisory for southern El Paso, Huerfano and
western Las Animas counties.
.LONG TERM...(Friday night through Thursday)
Issued at 301 PM MDT Thu May 18 2017
Friday night and Saturday...Models place a secondary piece of the
upper low over the southeast corner of the state Friday evening,
with snow for the higher elevations and rain for the lower expected
to continue through the evening. As the low pulls off to the e-ne
away from Colorado overnight, pcpn chances are forecast to diminish
quickly after midnight with unsettled nw flow aloft then settling
in. Another cold night on tap for the forecast area Fri night, and
additional frost/freeze highlights will likely be needed tomorrow.
Otherwise, look for temps to only warm into the 50s and 60s across
the area on Sat.
Sunday through Thursday...As the system exits the region, long range
models continue to keep Colorado under active northwest flow, with
multiple shortwaves crossing the region. There will be a nearly
constant threat of at least isolated convection over the higher
terrain and adjacent plains each day. A cold front dropping south
across the eastern plains Mon aftn will produce cooler temps for
Tue, then drier air filtering in behind is forecast to keep the cwa
dry for Wed. Temps will climb into the 60s to lower 70s each day,
but cooler on Tue with 50s and 60s expected. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 301 PM MDT Thu May 18 2017
At this time is looks like KPUB will mostly see VFR conditions
tonight and into Fri morning, however there may be some showers or
tstms in the area this evening. Fri morning there will be
increasing chances for rain again and ceilings will lower, possibly
into the MVFR category by late morning. KCOS will probably see some
showers/tstms in the area this evening with periods of MVFR
conditions. Chances for pcpn then are expected to decrease or end by
late evening with VFR conditions. Chances for pcpn are then
expected to increase during the day Fri, but VFR conditions are
still expected until toward evening when ceilings are forecast to
lower into the MVFR category. KALS is expected to have VFR
conditions until around 13Z Fri and then the ceilings are expected
to lower into the MVFR or IFR category. There may be some
showers/tstms in the vcnty of KALS this evening, and could move into
the area again Fri afternoon.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight tonight to 9 AM MDT Friday for
COZ085-087-088.
Winter Weather Advisory until 6 PM MDT Friday for COZ059-063-066-
068-081.
Winter Storm Warning until 6 PM MDT Friday for COZ058-060-082.
Winter Weather Advisory from 6 AM to 6 PM MDT Friday for COZ074-
075.
Winter Weather Advisory until 9 PM MDT this evening for COZ084.
Freeze Warning until 11 AM MDT Friday for COZ084.
&&
$$
UPDATE...MOORE
SHORT TERM...28
LONG TERM...MOORE
AVIATION...28
Area Forecast Discussion
National Weather Service Blacksburg VA
942 PM EDT Thu May 18 2017
.SYNOPSIS...
High pressure east of the Carolinas will continue to produce a
warm and humid southwest flow of air through tonight. The
increasing moisture will result in a threat for widely scattered
showers and storms into tonight, especially across the higher
terrain. A weak cold front will approach from the northwest
Friday, providing a better focus for showers and thunderstorms.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 935 PM EDT Thursday...
The forecast update late this evening will account for a
dissipation trend of the scattered showers and storms have have
been near the VA/NC border. The latest radar trends have been
showing a decrease in coverage thanks to loss of heating after
sunset, and activity in the east progressing into dryer air.
Have also tweaked hourly temperatures and dew points based upon
the latest observations and trends into the early morning hours
of Saturday.
As of 750 PM EDT Thursday...
Our forecast has been updated to reflect the better than
anticipated coverage of showers and storms east of the crest of
the Blue Ridge between rough Hillsville, VA and Prestonville,
NC. This activity is expected continue progressing southeast
this evening, but coverage will be waning as we lose the heating
of the day and the activity moves into a dryer air mass.
Other activity was focused across parts of the Northern
Mountains of North Carolina, especially over portions of Watauga
County.
Elsewhere, have downscaled the extend of the anticipate
scattered coverage across the mountains, to isolated or no
coverage the remainder of this evening.
As of 230 PM EDT Thursday...
Convection has been slow to develop this afternoon likely due to mixing
of dry air aloft and better focus remaining just west of the ridges
along a residual trough axis. MLCAPE values also reflect a bit less
instability with the best convergence along the southern Blue Ridge
where expect more coverage to develop over the next few hours. However
guidance remains inconsistent with the latest RAP showing some broken
clusters western third, while the HRRR more of a shotgun pattern
mountains into early evening. Therefore other than to cut back on pops
initially will keep in chances mainly west until just after sunset for
now.
Initial shearing shortwave will pass well north tonight allowing for a
continued weakening of the upper ridge overnight into Friday. May see a
few showers linger due to possible outflow and leftover instability
into late this evening, and over the far west for late tonight as
perhaps another band of convection arrives ahead of an upstream cold
front. This shown by a few models so after decreasing pops this
evening, will bump back up espcly northwest by daybreak. Otherwise will
call it mainly partly cloudy overnight under residual debris clouds
including spots of stratus/fog late. Should be quite muggy with
dewpoints keeping lows mostly in the 60s except for a few 50s valleys.
Still some uncertainty with convective coverage Friday ahead of a slow
moving backdoor front approaching from the north under flat flow aloft.
Guidance does show a weak shortwave rotating in ahead of the boundary
and may coincide with pre-frontal convergence during time of max
heating to spark some deeper bands of storms espcly west in the
afternoon. This in conjunction with better lapse rates aloft and decent
instability without much cap. However flow/shear remains quite weak
within a more westerly flow regime that could result in only scattered
clusters of shra/tsra as suggested by the SPC-WRF/Nam, with perhaps a
more organized area of convection to the northwest closer to the front.
Also early clouds along with far western showers could hinder
instability for a bit so running with mainly mid/high chance pops with
brief likelys mainly southwest sections where late day convergence
looks best. Appears temps similar to today pending the degree of
insolation with highs mostly 80-85 mountains and mid/upper 80s east
with more humidity around.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 230 PM EDT Thursday...
A back-door cold front draped from Ohio to northern Virginia will
sink south as a weak surface wave moves off the Virginia coast
Friday night. This boundary will become stationary over southern
Virginia Saturday morning. Some models are agressive with allowing
this front to move south during the day Saturday. However, with a
heat ridge across the southeast and no jet overhead, it will take
some strong diurnal convection along the boundary to help it move
south during the day. Strong convection maybe possible during the
mid afternoon, but the boundary may not start moving until after
sunset Friday evening.
Convection likely Saturday afternoon for area outside of the wedge.
Mechanisms will be a combination of diurnal heating, orographical
and frontal lift. As storms get going in the mid to late afternoon,
outflow boundaries will also help initiate convection over North
Carolina. Areas inside the wedge could see a showers with a few
rumbles of thunder from elevated instabilities.
Tricky temperatures forecast Saturday depending on where the wedge
stalls. Inside, temperatures will range from the upper 60s to mid
70s. Outside the wedge. temperatures could warm into the upper 70s
to mid 80s.
The wedge will sit over the area Saturday night into Sunday morning,
then erode during the day Sunday as a front moves over the Ohio-
Tennessee Valley. The piedmont may not see the wedge erode until
late in the afternoon. Showers from the front will enter the
mountains during the late afternoon/evening. Some strong storms are
possible especially with an eroding wedge boundary. Majority of the
showers will enter the mountains after peak heating, therefore
limiting the potential of strong storms to just a few. Showers
expected to move east of the Blue Ridge after midnight, then east
over the coastal piedmont by noon Monday. Jet dynamics and
instabilities remain high enough to keep some mention of thunder
overnight.
Another tricky temperatures forecast for Sunday with wedge eroding
and convection coming in late in the afternoon from the next front.
Thinking wedge will be gone by mid afternoon allowing temperatures
to warm very quickly before frontal showers move in. Sunday
afternoon temperatures should warm into the upper 70s to lower 80s.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 240 PM EDT Thursday...
The front and rain will clear the area by Monday afternoon. High
pressure will bring a brief period of dry weather from Monday
afternoon into Tuesday evening. A strong cold front will move across
the region Wednesday. A dry slot will grace the area Wednesday night
then the upper level portion of the storm will move across the area
Thursday.
Temperatures will remain close to normal for early next week, then
fall below normal to end the week.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
As of 740 PM EDT Thursday...
Primarily VFR conditions prevail across the region. A scattered
line of thunderstorms existed between roughly KTNB-KHLX-KMTV.
Potentially, of the TAF locations, KDAN may be impacted by some
of this activity over the next couple of hours. However, the
trend should be a weakening on with the loss of daytime heating
and the arrival of the precipitation into a dryer airmass.
Localized sub-VFR ceilings and visibilities will accompany the
heavy showers and storms within this activity.
Sub-VFR conditions in the form of patchy fog will impact some of
the terminal locations late tonight into early Friday morning.
Any sub-VFR conditions will dissipate two or three hours after
sunrise.
Better threat for greater coverage of afternoon
showers/thunderstorms Friday with periodic rounds of sub-VFR
possible Friday afternoon/evening as a frontal boundary moves
southeast toward the central Appalachians. Low clouds from
earlier burn off of fog along with possible convection to the
west could result in MVFR cigs through midday Friday mountains.
Otherwise wont include any shra/tsra mention on Friday as
appears most coverage wont occur until near or after the end of
the valid TAF period.
Extended Aviation Discussion...
The front is forecast to stall across the region into this
weekend, with best shower/storm chances over the mountains
Saturday afternoon/evening. Coverage should then trend more
isolated until late Sunday as this residual boundary lifts out
to the northeast ahead of another cold front approaching from
the west. This front may then bring another round of deeper
convection to the mountains by Sunday evening and over much of
the region into Sunday night. Front crosses the region Monday
morning with possible residual sub-VFR in the east early on and
across the mountains due to upslope flow through much of the
day.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/PM
NEAR TERM...DS/JH
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...DS/JH/PM
Area Forecast Discussion
National Weather Service Shreveport LA
1000 PM CDT Thu May 18 2017
.DISCUSSION...
The evening satellite imagery indicates an extensive area of
convective debris spilling E into the region from the ongoing MCS
over Srn/Ern OK, as well as sct supercells over Wcntrl TX.
Isolated to widely sct convection has increased over the last hour
or so over McCurtain County OK as well as the Nrn sections of SW
AR, where Srly low level winds just away from the LLJ have
increased to 30-40kts ahead of a broadly difluent region over
much of OK well ahead of the upper closed low spinning over Wrn CO
this evening. Although the earlier progs had suggested MCS
development a little later tonight where convection is ongoing
attm, the HRRR is also having to play catchup with the Srn most
edge of the bow about to enter Nrn Atoka/Pittsburg Counties in SE
OK possibly affecting Nrn McCurtain County OK between 04-05Z,
should it backbuild farther S. However, the progs do suggest that
this convection should continue to build more NE overnight,
consistent with embedded shortwave energy also ejecting NE ahead
of the closed low. The air mass over this region remains
moderately unstable this evening with MLCapes of 2500-3000 J/Kg,
with strong capping noted on the 00Z KSHV raob near H700 (and even
weak capping noted at FWD) limiting the Swd extent of convection
development overnight. Still can`t rule out an isolated svr threat
for our far NW counties given the extent of instability and the
increasing SSW LLJ, which should help sustain convection through
at least a portion of the overnight hours.
Have updated the forecast to lower pops a bit over SW AR/extreme
NE TX, but did maintain low to mid chance pops across the far NW
zones. Also removed pops for much of E TX/N LA/Scntrl AR as the
isolated and rogue -SHRA have diminished with the loss of heating.
Given the Srly winds staying up overnight, and the extensive
convective debris spreading E, with additional low stratus
developing/advecting N late, have bumped up min temps slightly
with temps only falling into the lower and mid 70s, with the
warmer temps confined to portions of E TX/extreme NW LA.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 712 PM CDT Thu May 18 2017/
AVIATION...
For the ArkLaTex, VFR even with vcsh near KLFK for a few hrs.
Overnight, Southerly winds will slack gust but keep 5-15KT. Climb
winds are S20-30KT and SW30-50KT for flight levels. Expect
stratus decks IFR/MVFR 09Z-18Z. A weak system approaching will
time well with afternoon heating on Friday for a few terminals
with VCTS late this cycle as clouds scatter to VFR. Area outlook
remains unsettle into weekend with a stronger system/fropa. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 74 88 73 83 / 10 30 20 60
MLU 72 88 72 86 / 10 30 20 50
DEQ 69 85 69 79 / 30 30 50 80
TXK 72 85 71 80 / 20 30 40 70
ELD 72 87 71 82 / 10 30 20 60
TYR 74 89 72 81 / 20 30 40 80
GGG 74 88 72 82 / 10 30 30 70
LFK 73 89 73 85 / 10 30 20 60
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Tonight)
Issued at 159 PM CDT Thu May 18 2017
Focus for tonight will be the threat for severe weather across
northeast Kansas. This afternoon, a warm front was noted across
east central Kansas oriented from east to west. Main concern this
afternoon will be if storms begin to develop along this warm front
as the HRRR has been depicting in model runs. CAPE near/south of
this boundary is over 3000 J/kg with effective bulk shear values of
50 knots. During the afternoon hours, the NAM also shows 0-1 shear
along this boundary around 25 knots, with steep mid-level lapse
rates. Any discrete storms forming along this boundary will have the
potential to quickly become supercellular with the main hazards
being large hail, damaging winds, and tornadoes. If storms do form
this afternoon, exact details for tonight look more unclear as
instability will be weaker and subsidence from storms may act to
alleviate severity later tonight. For tonight, storms that are
expected to fire up on the dry line located in southwestern Kansas
and extending southward into Oklahoma. Models have been fairly
consistent in having these storms congeal into a line/bow and move
through northeast Kansas this evening. This would bring a main
hazard of widespread wind damage across the area, although hail or
an embedded spin up tornado cannot be ruled out. Additional
development behind this line is possible bringing another round of
heavy rain to the area, increasing the potential for flash flooding.
This is especially true in areas in north central Kansas that have
already seen heavy rainfall totals earlier in the week. With the
potential for more developing showers and thunderstorms tomorrow, a
flash flood watch has been issued for the entirety of northeast
Kansas beginning this afternoon and extending into Saturday morning.
.LONG TERM...(Friday through Thursday)
Issued at 159 PM CDT Thu May 18 2017
The vast majority of the long term forecast period forecast effort
focuses on Friday and Friday night severe/flooding potential, with
periods beyond that generally trending toward a model consensus at
this time with minimal expected impacts through the remainder of
the forecast.
For Friday, much of the details will lie in how quickly convection
exits the area early Friday morning. Current indications are that
it will make a substantial eastward push overnight and exit the
region early. If this occurs, it would give much of the forecast
area more time to recharge instability as the true warm front
surges/mixes back north during the day in advance of a strong
upper level trough. Long, clockwise curved hodographs with low
LCL/LFC heights and rather steep lapse rates through the cloud-
bearing layer all point to another day with widespread severe
weather potential. This will include tornado potential across the
warm sector, and the most likely this warm sector will include
much of eastern Kansas with main uncertainty being in the
northwestward extent. There are two potential limiting factors.
1) Early day convection ends late and keeps the boundary layer
stable for much of the day, effectively mitigating instability.
2) Storms develop too close to each other, resulting in continued
hail and damaging wind potential but limiting overall tornado
potential.
Regardless, severe storms are possible with some potential for
another higher-end episode of severe weather. The other concern
will be flash flooding with multiple rounds of thunderstorm again
possible over what is likely to be saturated ground conditions
with elevated stream levels after tonight`s storms. WPC has the
area in a moderate risk for excessive rainfall and for good
reason, so have continued the flash flood watch through Friday
night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 636 PM CDT Thu May 18 2017
VFR conditions will occur outside of convection through 07Z. MVFR
cigs are expected after 07Z and prior to that with convection.
MVFR and ifr vsbys are expected with storms. Showers along with
isolated tsra are expected at TOP and FOE from 07Z-12Z then again
after 18Z Friday. Also some ifr cigs may move into the MHK area
after 19Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Saturday morning for KSZ008>012-
020>024-026-034>040-054>056-058-059.
&&
$$
SHORT TERM...Heller
LONG TERM...Barjenbruch
AVIATION...53