Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/31/18
Area Forecast Discussion
National Weather Service Bismarck ND
1000 PM CDT Wed May 30 2018
.UPDATE...
Issued at 1000 PM CDT Wed May 30 2018
The main adjustment with this update was to increase the coverage
of fog late tonight and early Thursday morning in central ND. The
presence of weak deep-layer winds beneath a shortwave ridge axis,
seasonably-high low-level moisture content that will be augmented
locally in some spots by recent rainfall, and a supportive stable
boundary layer per modified Richardson Number output all supports
the fog that`s been consistently simulated by the HRRR and GLAMP.
Given the setup, later shifts will need to monitor for a possible
Dense Fog Advisory issuance, especially over south central ND.
Meanwhile, initial convection has entered northwestern ND as the
first in a series of mid-level impulses in developing southwest
flow aloft have reached the area. Additional upstream convection
in MT may propagate into western and especially northwestern ND
through the night, but initially-moderate bouyancy that`s being
offset by weak shear will be replaced by weaker elevated CAPE on
the order of 400-800 J/kg after 06 UTC, but modestly larger wind
shear. The net effect should continue to be a generally low risk
of severe storms overnight, especially once instability decreases
somewhat over northwest ND where a more intense storm is ongoing
as of 03 UTC.
UPDATE Issued at 604 PM CDT Wed May 30 2018
We increased PoPs into the 40 to 50 percent range in northwest ND
this evening in respect to upstream convection propagating across
northeast MT as of 23 UTC. Simple extrapolation takes the leading
cells across the state line beginning about 00 UTC, and a time-
lagged consensus of recent HRRR iterations suggests that the
activity could make it as far east as a Bowbells to Parshall line
before it diminishes by late evening. MLCAPE of 500-1000 J/kg is
present, but effective shear is 20 kt or less, which will greatly
marginalize any severe threat. Diurnally-steepened low-level lapse
rates could support gusty outflow winds, though. Otherwise, the
convection in central ND is diminishing as convective processing
and expanding cool outflow is reducing instability, a process
that will only be hastened by the onset of boundary layer cooling
over the next one to two hours.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 203 PM CDT Wed May 30 2018
The main forecast issue in the short term period will be
shower and thunderstorm chances today and Thursday.
Surface and upper level low were located in the vicinity of the
southern James River Valley early this Wednesday afternoon.
Scattered showers and a few thunderstorms continue over central and
eastern ND within the circulation of the 50H low. Expect activity to
continue through the afternoon. Weak shear and modest instability
should inhibit severe activity, but a few stronger cells are
possible with small hail and locally gusty winds. Heavy rain will
be associated with these storms. Afternoon activity is expected
to diminish in the early evening over eastern portions of central
ND.
The next threat of thunderstorms will be late this evening and
overnight in the northwest portion of the state as convection
fires over Saskatchewan into north central MT today along a
surface cold front and pushes eastward. CAMS vary in the extent of
intrusion of convection into NW and even NC North Dakota before
it runs into less favorable atmospheric conditions of weaker bulk
shear and increasing CIN with the loss of daytime heating. The
cold front associated with this convection will become stationary
over nw/nc ND late tonight with patchy fog mainly along and north
of this boundary late tonight into Thursday morning. Also extended
a mention of patchy fog south through central ND with light
surface flow.
On Thursday, upper level ridging increases over central and eastern
ND as a western upper trough moves onto the western U.S. coast.
Think that most of the forecast area will see capping on Thursday
but the aforementioned stationary will be a focus for low level
moisture pooling and will reside close to upper level impulses
impinging on the mid level trough. The daytime hours over the
northwest and north central Thursday may be a will be a battle
along this boundary over the nw/nc between capping and convective
initiation. While most of the forecast area remains dry. Another
potential concern late Thursday afternoon will be the west central
into the southwest portion of the state. Strong surface heating
over the northern high plains of Wyoming and southeast Montana
will provide moderate to strong instability along the surface
trough. Deep layer shear of 30 to 40 knots becomes nearly
orthogonal to the surface trough. If daytime heating can overcome
the capping, isolated discrete severe convection could develop in
this area. The 12 UTC NAMNest hints at this possibility.
Convection here would likely succumb to strong capping before it
makes it too far east.
.LONG TERM...(Thursday night through Wednesday)
Issued at 203 PM CDT Wed May 30 2018
Thursday evening moderate instability and strong deep layer shear
supports the potential for organized severe convection over
eastern Montana and into northwest ND. Given shear orientation
somewhat parallel to the surface boundary, storms may quickly
cluster, with possible MCS formation along the international
border through the late evening and overnight sustained by a
strengthening low level jet. Scattered elevated convection may
develop across the remainder of western and central North Dakota
through the night with the low level jet, continued moisture
transport, Elevated Mixed Layer (EML) arrival and impulses in
southwest flow aloft. Although this is less certain.
A more significant severe weather event is possible across
western and central North Dakota on Friday. This has been
consistently shown by the global suite and CIPs analogs. Most of
western and central North Dakota remain in a Slight Risk in the
SPC Day 3 outlook. Moderate to strong instability is forecast to
build across central North Dakota within the warm sector of the
surface low. Deep layer shear is forecast to be sufficient for
organized convection. The highest shear however may potentially
lag the cold/occluding front. Strong forcing with the arrival of
the significant shortwave and mid level jet is expected late
Friday afternoon through Friday night, coupled with low level
forcing with the occluding frontal boundaries. All threats remain
possible as storm mode may range from initial supercells to
upscale growth into linear segments. Certainly questions of
capping and cloud cover impacts from overnight convection still
remain, and likely will into Friday. However, the consistent
signal, strength of forcing, and instability and shear parameter
spaces all point to a possible widespread severe threat across the
area on Friday.
We dry out over the upcoming weekend. However a stray shower or
thunderstorm is possible over the north central Saturday
afternoon. Slightly cooler late in the weekend into next week with
chances of showers and thunderstorms returning Tuesday and
Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 1000 PM CDT Wed May 30 2018
Localized MVFR conditions in thunderstorms are possible in western
and especially northwestern ND tonight, possibly impacting KISN. A
new round of more intense and possibly severe storms will likely
erupt after 21 UTC Thursday near a surface front in western ND, so
the 06 UTC TAFs may reflect higher probabilities of impacts at the
KISN and KDIK terminals late Thursday afternoon and evening.
Meanwhile, the presence of a moist air mass and light winds will
likely favor fog and possible low stratus development in central
ND late tonight and Thursday morning. IFR to LIFR conditions are
possible, especially at KBIS and KMOT between 10 and 14 UTC.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...CJS
Area Forecast Discussion
National Weather Service Columbia SC
1042 PM EDT Wed May 30 2018
.SYNOPSIS...
High pressure centered off the Southeast Coast will direct a
moist southerly flow into the forecast area through Thursday.
The flow should turn more westerly over the weekend with ridging
extending from the Atlantic into the Gulf of Mexico. Slightly
drier air will move into the forecast area in the westerly flow,
but enough moisture will continue for scattered thunderstorms.
&&
.NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
A moist southerly flow across the region continues with
precipitable water around 2.0 inches. Convection has dissipated
for the evening. Both the RAP and HRRR indicated a weak short
wave over southern GA moving northeast into the forecast area
late tonight. Although models have timing differences....should
see an increase in showers especially across eastern SC toward
daybreak. Otherwise expect cloudy skies with lows mostly in the
lower 70s.
&&
.SHORT TERM /8 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
The models maintain deep moisture through Thursday in a southerly
flow on the backside of offshore surface high pressure and
ahead of upper troughing. Showers and thunderstorms will be
likely by early afternoon as a shortwave moves up the coast.
The heaviest rain will therefore be across the eastern Midlands,
and there will also be a continued chance of localized flooding
with precipitable water around 2 inches. A second shortwave will
move in from the west during the evening. The models indicate
moderate instability with surface-based LI values -5 to -8, so
damaging wind will also be possible with the thunderstorms.
The models depict the low-level flow veering more westerly Friday
with deeper moisture shifted farther east. However, a front
approaching from the west should help support thunderstorms in
the late afternoon and evening. The GFS and NAM support best
pops with the front after 8 PM. It will be quite warm with highs
in the low to mid 90s, causing increased instability, and the
models show surface-based LI values -8 to -12. Shear is weak,
but any storms that develop could produce damaging wind or hail.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Upper troughing will remain over the area through the middle of
next week. Embedded shortwaves and diurnal heating mean that
showers and thunderstorms will continue to be possible this
afternoon, but drier air moving into the region will keep
coverage spotty. There is a low chance Saturday, with a better
chance Sunday as another front moves through. Drier conditions
are more probable Monday through Wednesday, but convection
cannot be completely rules out. Temperatures will be seasonable
through the period with highs in the mid 80s to low 90s and
lows in the mid 60s to low 70s.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
High confidence for restrictions overnight in moist airmass.
Observations at 02Z indicated patches of MVFR/IFR cigs
affecting the TAF sites. Persistence forecast as well as LAMP
and HRRR guidance suggest MVFR/IFR cigs becoming more widespread
after 06Z. Should see conditions improving to VFR from mid to
late Thursday morning. Although showers have ended for the
evening...may see showers redevelop toward daybreak as a weak
upper level disturbance approaches the area. Scattered to
numerous showers and thunderstorms still expected to develop
Thursday afternoon as the airmass becomes more unstable.
Light south wind overnight will become southwest 5 to 10 knots
Thursday morning.
EXTENDED AVIATION OUTLOOK...Expect mainly diurnal showers and
thunderstorms through Monday.
&&
.HYDROLOGY...
Heavy rain in the headwaters may lead to river flooding later in
the week. With area lakes already near full pool, expect most
water to be passed on through the dams. Expect area streams and
rivers to have elevated flows through the rest of the week.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service State College PA
1025 PM EDT Wed May 30 2018
.SYNOPSIS...
The remnants of Alberto are pretty much on top of Kalamazoo as
of 10PM and moving northward. A deep southerly flow of very
moist, tropical air into the region will keep local conditions
warm and humid with a daily chance of showers and thunderstorms
through the rest of the week.
&&
.NEAR TERM /THROUGH TONIGHT...
Radar shows mainly light showers developing and streaming north
in the moist tropical airmass. The remainder of the overnight
will be muggy with scattered showers and perhaps a rumble of
thunder. The HRRR shows the shower activity increasing as we
move into the wee hours of Thursday morning. It hints at the
first area of these showers moving off to the north by mid
morning before new convection breaks out in the soupy air.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
the Remnants of Alberto over NW Indiana gets absorbed into the
general south-southwesterly flow aloft (on the western periphery
of a sharp upper level ridge), and passes by pretty much
harmlessly to our northwest then north on Thurs. However, this
compact storm will enhance a boundary along the St Lawrence and
Lower Glakes, and eventually push it SE across the Commonwealth
on Friday.
Temps dip a bit in many locations on Thursday with cloud cover
being thicker and more widespread than today. Therefore it
appears like instability will be limited until late in the day.
CAPEs climb to healthy levels, but distinct triggers for
organized larger- scale lift are lacking and instability is
questionable.
Similar to today (Wednesday), the best chance for thunder will
be across the southwest zones.
The boundary to our north will slowly push it`s way toward us
Thurs, and should pass through the state during the day Friday.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
An upper level trough will dig southeast from the western Great
Lakes Thursday night into the southern Mid Atlantic coastal
region over the weekend. Shortwaves reinforcing the upper trough
along with some blocking downstream will cause the trough to
slow down and possibly cut off for a time near the Delmarva on
Sunday. Model guidance shows another upper trough moving into
the Northeast U.S. early next week.
The anomalously high/near record level [tropical] precipitable
water values along with broad upper level support should
contribute to scattered convection with heavy downpours and
increased risk of localized flash flooding Thu. Night into
Friday. Showers will linger into the weekend especially across
south central and southeastern PA. A push of relatively drier
(less humid) air should arrive by early next week as PWs return
to near normal.
Temperatures trend relatively cooler through the weekend into
early next week. The mean upper troughing will maintain an
unsettled pattern with at least some chance of rain/showers
into early June.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Light showers continue to move through central PA. Latest sat
shows overrunning as MVFR cigs continue to move over the
region. Expect these cigs to lower through the overnight hours.
The main chance for wet conditions and lower MVFR and IFR
conditions arrives later tonight and continues into Friday as
increasing upward motion develops over our region ahead of an
upper level disturbance moving north- northeast from the SW part
of VA. IFR cigs overnight will continue before slowly improving
late tomorrow morning. However scattered showers will keep at
least MVFR cigs through 21Z.
.Outlook...
Thu-Fri...AM rain/low cigs possible. Intermittent shra/tsra
impacts.
Sat-Sun...AM showers/low cigs possible. Sct showers.
&&
.HYDROLOGY...
Precipitable Water values in the 1-1.5 inch range today will
continue to climb to nearly 2" for Thurs-Fri in the S and up to
1.5+" N. The anomalous moisture and some slow movement/MBE
vectors on Thurs and Fri could put the region as risk for flash
flooding, esp in the srn tier. WPC excessive rain outlooks place
the srn half into SLGT risk for Thurs and constricts it a bit
to the S/W on Friday. Will mention this possibility of +RA in
the HWO for now and pass the buck to future shifts for more
consideration on flood watch potential.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Dangelo/Lambert
LONG TERM...Steinbugl
AVIATION...Lambert/Ceru
HYDROLOGY...
Area Forecast Discussion
National Weather Service Wilmington NC
925 PM EDT Wed May 30 2018
.SYNOPSIS...
Numerous showers are expected Thursday, otherwise showers will
be isolated to perhaps scattered through Friday. The probability
for showers and thunderstorms will likely increase again ahead
of a cold front Saturday and Saturday night with unsettled
weather perhaps lingering into Monday. Drier air will slowly try
to build into the area from the north Tuesday and Wednesday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 930 PM Wednesday...As expected, showers dissipated quickly
with the stabilization of the boundary layer, and dry weather
should continue at least the next 6-7 hours. The HRRR and RAP
look at least 3-4 hours too fast with their redevelopment of
showers late tonight versus other models and just by timing the
mid-level disturbance now moving into SE Georgia. I prefer the
slower GFS, WRF-NMM and WRF-ARW models which bring showers up
to the Santee River near daybreak, then across the remainder of
our forecast area during the mid to late morning hours. No
further changes have been made to forecast lows which remain in
the 72-76 range, almost 10 degrees above normal.
As of now, Wilmington`s rainfall total for this month stands at
14.36 inches, 5.24 inches above the next wettest May in history
(9.12 inches in 1956). Wilmington`s rainfall records began in
1871. -TRA
Discussion from 300 PM follows...
Just a smattering of showers this afternoon concentrated moreso
down south where the boundary layer has been able to recover
somewhat. Will adjust pops for the afternoon hours accordingly
but overall no significant changes for the next few hours.
Tonight should be essentially a repeat of last night with little
to no activity. Guidance has trended somewhat wetter for
Thursday via a slightly more conducive mid level environment
working on the very moist column. We are advertising good chance
to in some cases likely pops. Overnight lows on the warm side
of guidance with daytime highs Thursday in the lower and middle
80s highly dependent on the extent of convective coverage.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...As mid level flow turns from SW to W
Thursday night PW values will drop from 2.2 to 1.7", which
takes them from near record values to the `mere` 90% max values
climatologically. It is tempting to offer up a rain-free
forecast (assuming no evening convection lingers from the near
term) but there are still some vorticity maxima traversing the
area so will maintain the inherited low POPs. Friday brings
weak lapse rates through 700mb with slightly higher rates atop
this level as flow turns to NW in the 600-700 layer as another
batch of disturbances approach from the NW. Assuming deep layer
ascent associated with these features hold off until Friday
night Friday afternoon may too offer up a relative minimum
activity level. This idea is supported by the operational GFS
and WRF. Both models show a dissipating convective signal
approaching from the NW. The WRF washes out all QPF before
entering the area whereas the GFS advects some into the region.
Though the latter is a known bias of many models will maintain
rain chances into Friday night due to the high low level
moisture available.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...Forecast Area will be in between upper high
centered across the Bahamas and western Caribbean islands an upper
low wobbling across the Mid-Atlantic States during the weekend. The
eastern Carolinas will be under the influence of NW flow aloft. One
vigorous mid-level shortwave trough in this flow will move across
the FA Sat morning and then another one late day Sat and Sat night
coincident with a surface cold front. This front should get
reinforced with the passage of another shortwave trough later
Sun/Sun eve. The upper low should then open up Mon as it becomes
absorbed by a much stronger system diving SE across SE Canada and
the Northeast States. This large system will then move slowly
offshore of the Northeast States Tue and Wed. Perturbations embedded
in NW to WNW flow will periodically move across the Carolinas early
into mid next week, thus making it virtually impossible to not
include at least isolated to scattered convection on a daily basis.
However, at the surface, high pressure will attempt to build
southward and into the Southeast States Tue night and Wed. Given the
progressive pattern and the extended range, confidence is not high
enough to include numerous or widespread convection in any 12 hour
period, however, generally expect the afternoon and early eve hours
to be a more favored time of day for convection although convection
should persist longer Sat night. Showers and thunderstorms should be
fewer by the middle of next week as compared to the weekend and
early in the new week.
The warmest day of this period is forecast to be Sat when highs will
be in the upper 80s and lower 90s, warmest inland. Prevailing WSW to
W flow should allow the beaches to warm to the upper 80s as well.
Otherwise, daytime highs should be in the seasonable mid and upper
80s. Lows will be mainly in the lower 70s Sat night with upper 60s
and lower 70s dominating the balance of the forecast period.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 00Z...A rather organized cluster of convection that formed on
an outflow boundary will slowly wane over the next couple of hours.
Looks like stratus will once again return mainly after midnight.
Light southerly flow. Thursday, another repeat performance for
showers. With low LFCs, will not take much heat to kick them off,
probably around 15Z, with peak coverage moving inland around 18-19Z.
Brief IFR visibilities are possible with isolated thunder.
Extended Outlook...VFR. Tempo MVFR/IFR in AM fog/stratus, and
brief MVFR/IFR in mainly late morning through early evening
showers/thunderstorms.
&&
.MARINE...
NEAR TERM /THROUGH THURSDAY/...
As of 930 PM Wednesday...Southwesterly winds 10-15 kt should
decrease to around 10 kt overnight as what`s left of former
subtropical storm Alberto weakens across the Great Lakes. Seas
remain in the 3 foot range across the coastal waters, with
little change anticipated overnight. Largely dry weather
overnight may begin to change toward daybreak as a disturbance
approaches from the south. Shower and t-storm potential should
increase substantially after daybreak Thursday. -TRA
Discussion from 300 PM follows...
Little to no change in the synoptic pattern yields a
persistence forecast for the marine community. Expect south to
southwest winds of 10-15 knots through the period with
significant seas of 2-4 feet.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Summer-like quasi-unchanging conditions in
store for the short term. High pressure will sit well off the coast
and a piedmont trough may weakly take shape. This will promote a
continued southwesterly flow across the waters. In this coast-
parallel flow there will be a nearshore vs offshore gradient in wave
height and a blend of WNA and SWAN shows that swell energy briefly
leads to 5 ft seas out at 41013. Across the 20nm forecast zone
however will see a continuation of 3 to 4 ft.
LONG TERM /SATURDAY THROUGH MONDAY/..
As of 300 PM Wednesday...SW winds will still be the rule ahead of a
cold front Sat. The wind direction will veer to W Sat night and to
NW by Sun morning. The wind direction should then back slightly
during Sun ahead of a reinforcing cold front before shifting to
N Sun night in its wake. N winds will then veer to NE Mon and
possibly become variable Mon night. The strongest winds should
be Sat, up to 15 to 20 kt. Otherwise wind speeds Sat night should
be diminishing to 10 to 15 kt with 10 kt or less for the remainder
of this forecast period. Seas of 2 to 4 ft into Sun will subside
to 2 to 3 ft beginning late Sun and through the end of the forecast
period.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Advisory until midnight EDT tonight for NCZ107.
MARINE...None.
&&
$$
SYNOPSIS...RJD
NEAR TERM...TRA/SHK
SHORT TERM...MBB
LONG TERM...RJD
AVIATION...DL
Area Forecast Discussion
National Weather Service Reno NV
237 PM PDT Wed May 30 2018
.SYNOPSIS...
Low pressure approaching the West Coast will move inland and
bring gusty afternoon and evening winds through Thursday, with
isolated showers and thunderstorms mainly well east of Fallon and
Lovelock. Dry conditions with a warming trend are expected Friday
through the weekend.
&&
.DISCUSSION...
A weak trough of low pressure along the Pacific Northwest coast
has induced stronger thermal gradients/winds across northeast CA
and western NV, with gusts generally in the 25-35 mph range so
far today. Meanwhile, isolated showers and thunderstorms are
underway over central and northeast Nevada in the area of best
convergence and instability ahead of the low. Elsewhere, a lack of
convergence and somewhat drier air has limited cumulus development
and no showers or storms are expected. The only exception could
wind up being well north of Susanville and in the Surprise Valley
where a few showers or brief thunderstorms could develop by early
evening (as shown in HRRR simulations), although chances look
low.
The aforementioned weak trough will move over northern California
and Nevada on Thursday. This will bring another day of breezy
afternoon and evening winds, although top wind speed potential
looks slightly lower (20-30 mph) as thermal gradients relax some
with cooling working into the Great Basin. A few showers north of
Susanville/Gerlach or showers/thunderstorms well east of Fallon
and Lovelock will still be possible although the best chance will
shift over into northeast Nevada near a cold front.
Friday through Sunday, moderate-strength high pressure builds over
northeast CA and western NV for a warming trend. Highs will reach
10-15 degrees above average by Sunday with 80s to near 90 for the
lower valleys. For the first half of next week, weak troughing
will return for a gradual cool down to near average temperatures.
No precipitation is expected Friday through Wednesday. -Snyder
&&
.AVIATION...
Breezy south to southwest winds this afternoon will switch to
southwest to west for Thursday afternoon. Wind speeds should
decrease slightly for Thursday with peak gusts generally to
around 25 kts. Isolated showers should remain in similar locations
as today (north of KSVE and well east of KLOL/KNFL), with a weak
thunderstorm or two possible over extreme eastern Churchill and
Pershing Counties (but more likely farther east).
Conditions improve Friday this weekend with no storms expected
and decreasing winds. -Snyder/Dawn
&&
.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 9 PM PDT this evening NVZ002.
Lake Wind Advisory until 9 PM PDT this evening for Washoe Lake
in NVZ003.
Lake Wind Advisory until 9 PM PDT this evening NVZ004.
CA...Lake Wind Advisory until 9 PM PDT this evening CAZ071.
Lake Wind Advisory until 9 PM PDT this evening CAZ073.
Lake Wind Advisory until 9 PM PDT this evening CAZ072.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Tulsa OK
835 PM CDT Wed May 30 2018
...UPDATE...
.DISCUSSION...
Main concern for the rest of the night is the likelihood of a
severe MCS moving through at least a portion of northeast Oklahoma
early Thursday morning. Severe thunderstorms have already
developed early this evening across portions of the Oklahoma and
Texas panhandles, and this activity will continue to move eastward
this evening and early tomorrow morning. Some increase in coverage is
likely as the low level jet increases later tonight. Low level
moisture has pooled across portions of northeast Oklahoma along
and north of a subtle boundary laying just north of Highway 412
right now, per Mesonet observations. Dew points to the north of
the boundary are in the upper 70s in a few spots, with a marked
drop off into the lower 70s near and south of Interstate 40. Low
level wind fields in the HRRR show that this boundary will
continue to move northward this evening, likely lying across parts
of southern Kansas by the time the MCS reaches areas this far
east. This should mean that the instability maximum would be
located along and north of the Kansas border after midnight as
well, leading to an eventual east-northeasterly propagation of the
strongest portion of the MCS. As a result, confidence in severe
weather occurrence is highest in portions of northeast Oklahoma
along and to the north of Interstate 44.
Major changes to the going forecast include an increased temporal
resolution in the POP grids, delaying thunderstorm onset until
11 pm, and decreasing low temperatures across portions of
northeast Oklahoma most likely to see heavier rainfall overnight.
Updates already out.
&&
.PREV DISCUSSION... /Issued 330 PM CDT Wed May 30 2018/
DISCUSSION...
Another complex of thunderstorms is forecast to move across at
least the northern portions of the forecast area late tonight
followed by several days of heat and humidity before a cold front
arrives Saturday.
Storms have already formed across the higher terrain in southeast
Colorado and northeast New Mexico this afternoon, and this marks
the beginning of tonight`s convective complex. Storms will form
into a forward propagating MCS that will track across southern
Kansas and northern Oklahoma, primarily after midnight. The main
threat will be damaging wind gusts and heavy rain. There will be
a limited threat for tornadoes given that the low level inflow
will be greater than last night`s complex. In any event, the
potential is there for damaging wind gusts tonight. If storms can
train, particularly along the KS/OK border, there would be an
increased chance of localized flash flooding.
There will be low chances for storms continuing early on Thursday
especially if storms can form along any residual outflow
boundaries, so will maintain low chances northeast.
The heat and humidity will take center stage by Friday, when heat
advisories will likely be needed. The cold front arrives Saturday,
and the timing will be important for high temperatures and related
heat index values. If drier air can work into the northern
sections of the forecast area earlier on Saturday, it will keep
heat index values across northeast Oklahoma just below criteria.
Areas south of I-40 will likely see some areas reach the 100
degree mark.
Upper ridge builds in for the beginning of next week, after a
"cooler" Sunday with highs only in the mid to upper 80s. There are
minimal chances for showers and storms next week, but will leave
the going forecast dry for now.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...22