Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/24/18
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
521 PM MDT Wed May 23 2018
.AVIATION...
00Z TAF CYCLE
SHRA/TSRA will continue to move northeast around 20 kt as they
progress across the eastern plains this evening. TSRA will be strong
to locally severe with large hail, high winds, torrential rainfall,
and frequent cloud to ground lightning strikes. Low clouds will
redevelop again tonight along and east of the central mt chain in the
wake of the storm activity. Confidence however is not as high on
coverage of clouds and potential IFR impacts.
&&
.PREV DISCUSSION...221 PM MDT Wed May 23 2018...
.SYNOPSIS...
Another round of afternoon thunderstorm activity has begun across
eastern New Mexico today with several storms becoming severe
producing large hail. A few storms could become tornadic across the
southeast. Storm activity will gradually move east into Texas this
evening. Thursday will see lesser thunderstorm activity with the main
focus starting over the Sacramento Mountains moving over southeastern
NM. Drier air and warmer temperatures move in across the state Friday
and through the weekend.
&&
.DISCUSSION...
Today`s crop of afternoon t-storm activity has begun to fire off the
eastern slopes of the ctrl mtn chain. SW flow aloft remains with sfc
Gulf moisture remaining, allowing for plenty of MLCAPE upwards of
3000 J/kg. The one limiting factor will be the bulk shear only
reaching up to about 30 kts, while still strong enough to allow for
severe, storms today will once again likely be pulsy. Directional
shear will be such to allow for the potential of an isolated tornado
or two in the strongest cells across the southeast. The HRRR has
continued to show the strongest cells remaining over the eastern
third of the state, moving into Texas sunset. Areas that have
already received good rainfall amounts in the previous days will be
at risk for localized flash flooding from strong downpours.
SW flow will will weaken Thursday with ridging starting to build
over southern NM. Enough Gulf moisture will still linger over the far
SE to allow for a few more storms firing off the Sacramento Mtns and
Chaves County. The rest of the state will continue to see drier air
moving in with warmer temperatures. All areas will see PoPs fall to
nil Friday with well above normal temperatures. Temperatures continue
to rise Saturday before falling across the west Sunday as a large
upper low moves into the Great Basin. SW flow will strengthen across
the east Sunday increasing the risk of critical fire weather.
Temperatures trend back up across the west, while remaining well
above normal across the east early next week. Increased chances for
precipitation may return by mid next week as another trough looks to
move across the central Rocky Mtns.
24
&&
.FIRE WEATHER...
...RETURN OF CRITICAL FIRE WEATHER CONDITIONS LATE WEEK AND INTO
THE WEEKEND...
Very dry air has spread farther east today into the Rio Grande
Valley. Marginal critical conditions are expected for parts of
central and western NM through the remainder of today. Deeper
moisture remains in place across eastern NM where the threat of
strong storms with locally heavy rainfall continues. Recoveries
overnight will be fair across central and western NM and very good
to excellent across the east with more low clouds.
A ridge of high pressure will build northward into NM Thursday and
Friday with above normal temperatures and lighter winds. The focus
for isolated storms will continue over eastern NM Thursday then
mainly over far southeastern NM Friday. The west will remain very
dry with single digit min humidities and poor recoveries. Haines
values of 6 will be common with super Haines for parts of the Rio
Grande Valley and western NM both days.
The upper ridge will break down quickly Saturday and lead to more
widespread strong southwest winds across NM. Critical fire weather
conditions Saturday will be followed by poor overnight recoveries,
then another round of critical fire weather Sunday for central and
eastern NM. Critical conditions may occur through Monday as an upper
wave ejects slowly northeastward across Colorado.
Guyer
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Bismarck ND
1020 PM CDT Wed May 23 2018
.UPDATE...
Issued at 1007 PM CDT Wed May 23 2018
Pops are the main problem for the late evening update. Cut back
on pops quite a bit overnight but did keep some pops mainly in the
west and south central to the James River Valley. Current
convection over southwest ND into northeast MT is expected to
continue to lift northward. Lately this convection has been
producing some small hail and gusty winds to around 40 mph. Expect
this trend to continue, but an isolated severe wind gust is still
possible. Convection over Dickey and Mcintosh counties continues
to lift slowly north within an area of maximized cape. However,
expect CIN to continue increasing, which should help suppress
these storms. Localized heavy rain and small hail can still be
expected over the next hour or so. Farther south, stronger
convection over west central South Dakota is forecast to lift
north and east into north Dakota after midnight. Experimental HRRR
seemed to have a good handle on current convection and this is the
model we leaned toward for pops going forward overnight. This
brings a few stronger cells into south central ND after midnight
and lifts them almost due north as they slowly weaken.
Climatologically not a favorite time for severe weather but this
is when the forcing from the upper level system will be maximized
so a stronger thunderstorm late tonight over central can not be
ruled out.
UPDATE Issued at 648 PM CDT Wed May 23 2018
Latest Radar and satellite imagery shows convection trying to fire
over southeast ND with a strong to severe cell just south of
Dickey county in the southern James River Valley. Throughout the
afternoon, any convection here has had a hard time maintaining
its intensity. 00 UTC Bismarck sounding does show some capping
over the are, so will see if this convection can overcome this.
The most unstable area in the region remains from this convection
and back west northwest toward Bismarck. If we don`t see the
convection maintain itself over the James River Valley, or
additional convection doesn`t fire over the south central in the
next couple hours, it may not be until stronger forcing arrives
later tonight. Farther west, convection remains ongoing over
eastern Montana and into western South Dakota. This convection may
also push into western ND later tonight.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 250 PM CDT Wed May 23 2018
Convective potential highlights the short term forecast.
The CAMs through the 18 UTC HRRR suggest the the mostly likely
area for strong to severe convection is across northwest North
Dakota this evening. This would be in association with a
convergence line/inverted trough from across southeast Montana
into northwest North Dakota. GOES-East trends through 2020 UTC
depict a growing cumulus field under the dry slot across Montana,
with deeper convective initiation possible in the next 2-3 hours
that would propagate into northwest North Dakota this evening.
Deep layer shear and thermodynamic profiles support a possible
severe threat through sunset. Elsewhere across western and central
North Dakota, the potential convective coverage and severity
still remains uncertain, and is limited by weak forcing and cloud
cover. The one exception would be the James River Valley this
evening as convection that initiates across central South Dakota
may propagate northeast aided by a low level jet and the arrival
of greater mid/upper level forcing. An isolated severe threat is
possible.
For Thursday, the upper level low across Montana today will
propagate across North Dakota with an associated surface cold
front. Moderate CAPE with surface dewpoints in the 60s is expected
ahead of the front with deep layer shear of around 20-30kts. SPC
has the Turtle Mountains through the James River Valley in a
marginal risk for severe thunderstorms Thursday afternoon, with a
greater risk further east where instability will be greater.
Scattered organized, discrete convection is possible after 21 UTC
along the front. Its development seems to have a bit better
predictability given the greater forcing.
.LONG TERM...(Thursday night through Wednesday)
Issued at 250 PM CDT Wed May 23 2018
Above normal temperatures Friday through the weekend highlight the
extended forecast.
The 00 UTC NAEFS 850 mb mean percentiles from their 90-97.5th
percentiles Friday through the weekend signal a period of above
normal temperatures. With favorable westerly winds, widespread
highs in the upper 80s and lower 90s are forecast on Friday.
While mixing is weaker Saturday, the airmass is warmer and
widespread highs in the lower to mid 90s are possible. Above
normal temperatures in the 80s and lower 90s may continue on
Sunday with the upper level ridge across the Northern Plains. An
active thunderstorm period is possible late Sunday through mid
next week with southwest flow aloft. This period will have to be
monitored for severe convective potential.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1007 PM CDT Wed May 23 2018
VFR conditions to begin the TAF period. Expect mainly VFR
conditions through the period, but scattered convection remains
possible at all TAF sites. Some of these storms could be strong to
severe with large hail and damaging winds. But uncertainty remains
high. Southerly surface flow continues tonight. Flow turns
west over western ND Thursday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...PA
LONG TERM...PA
AVIATION...TWH
Area Forecast Discussion
National Weather Service Birmingham AL
734 PM CDT Wed May 23 2018
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
The most concentrated convergence zone evident this morning has
migrated to the southern extent of Central Alabama this afternoon.
As mentioned in previous discussion, numerous boundaries remain
over the area and expect additional showers/storms to develop as
the afternoon progresses. Due to the low clouds and fog east, this
area will be the last to have some development, but nonetheless,
at least some scattered activity. The highest rain chances remain
south and west with likely to categorical until sunset.
Rather weak low pressure surface and aloft will remain from
central Georgia into southern Mississippi into Thursday. An area
of upward motion rotates around the low overnight, which should
kick off some activity after midnight in southeast areas. The
highest rain chances will be close to where we experienced 3-6
inches last night, and will need to be monitored closely due to
saturated ground conditions.
Slightly drier air and a shift in the pattern will push the
highest rain chances farther south on Thursday, with an axis near
I-85 and US 80 and southward.
The National Hurricane Center has increased the chances of
tropical to subtropical development in the northern gulf to 60
percent. The GFS is the outlier with this system so far, but at
this time, it still looks like there will be a heavy rain threat.
Will add isolated mention Friday and Saturday.
75
Previous short-term discussion:
Numerous boundaries are located over Central Alabama this
morning. These boundaries range from a mid level trough, a low
level trough, rain/no rain boundary, cloud no cloud (differential
heating) area, fog/no fog, and finally storm scale outflows. The
latest RUC analysis has much of the area in the relative humidity
maximum, with precipitable water values 1.8 inches or higher. Due
to this moisture content, microburst indices are low today. But
SBCape values are around 2500 with an instability maximum also
near us. 850-300 mean winds are rather light and lower level
convergence is not hugely outstanding, but enhanced near the
boundaries. Therefore, some of the stronger storms will be
capable of brief very heavy rainfall on the order of a few inches
in a short period of time and some gusty winds from precip
loading. The coverage of the heavy rain potential is should remain
relatively small, but where it rains, it will rain. Increased rain
chances west and south with likely to categorical rain chances
south of I-20.
75
Previous short-term discussion:Today and Tonight.
A concentrated area of heavy rainfall fell over Lee County overnight
with radar rainfall estimates of 4-6 inches over the far southeast
portion of Lee County. This activity was along a low level trof axis
and decent convergence enhancing rainfall rates. The low level trof
axis is forecast to push slightly southward today, with convergence
weakening due to a decrease in low level inflow south of the
boundary. Do not expect a repeat of excessive rainfall rates today
or tonight, but the areas along and south of I-85 will have the best
chance of rain today and tonight. There also appears to be a zone of
mid level convergence setting up across west Alabama by early
afternoon, so there is a chance of showers and a few thunderstorms
for a majority of central Alabama. Better chances for thunderstorm
activity today will be west of I-65 where surface temperatures will
be warmer. Shower and thunderstorm activity will diminish in areal
coverage this evening, but some activity will likely linger
overnight south of I-20.
58/rose
.LONG TERM...
Thursday through Tuesday.
High rain chances continue on Thursday as the moist air mass
remains in place. The low to mid-level circulation/remnant MCV
that has been hanging around the past couple days will initially
be over Georgia, but some high-res models retrograde its remnants
westward during the day. Drier air will briefly filter in across
the far northern/northwest counties.
A very stagnant upper-level pattern will be in place across the
Southeast and the Gulf throughout the forecast period, as a
southern-stream anomalous trough becomes trapped underneath mean
ridging in the northern stream. At the surface, low pressure is
expected to develop near the Yucatan by the end of the week and
lift northward towards the northern Gulf Coast this weekend. NHC`s
latest outlook indicates a 50% chance that this will become a
subtropical or tropical system. The GFS remains an eastern outlier
with this system tracking this system along the Florida
Peninsula. The ECMWF and its ensembles as well as the Canadian are
in better agreement that this system will lift towards the
northern Gulf Coast, putting much if not all of Central Alabama in
the moist eastern side of the system. Once it moves inland, it is
expected to stall out as a cutoff low next week. While wind shear
associated with the upper-level trough will probably prevent a
strong system from forming, slow-moving tropical depressions and
weak tropical storms have historically been heavy rainfall
producers. A tropical-like air mass is already in place and deeper
tropical moisture will move in by this weekend. Isolated flash
flooding will be possible almost any day. Daily high rain chances
will have a cumulative effect, and the best chance for more
organized flooding will come when 850mb moisture transport
associated with the low pressure system arrives by Sunday. There`s
still plenty of uncertainty regarding rainfall amounts and
timing, keeping confidence on the lower end at this time, but it
seems prudent to add a mention of flooding to the HWO for the
Sunday-Tuesday timeframe. Latest 7-day QPF from WPC indicates 3-6
inch area-average amounts across the area. Low-level wind fields
appear too weak to support any tropical tornado threat at this
time.
32/Davis
&&
.AVIATION...
00Z TAF Discussion.
Convection is tapering down with focus tonight over MS, the AL
gulf coast, and GA. Could see some MVFR patchy fog tonight well
after midnight, but high cloudiness will need to thin out some
first. Some MVFR cigs will come in from the east and south and
could reach TOI in the AM. Afternoon TS will be possible again
with best chances in southern part of the state. Have added in a
mention at TOI for Thursday afternoon as we remain in a wet
pattern.
08
&&
.FIRE WEATHER...
A moist pattern is expected over the next seven days and should
result in daily rain chances. Patchy fog and low clouds will be
possible each morning particularly where rainfall occurs during
the prior afternoon and evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 67 86 67 82 66 / 20 40 30 60 40
Anniston 68 85 68 82 66 / 30 40 40 60 40
Birmingham 69 87 69 85 69 / 20 40 30 60 40
Tuscaloosa 69 89 69 86 68 / 30 40 40 60 40
Calera 67 86 68 84 67 / 30 50 40 60 40
Auburn 68 82 68 81 67 / 60 60 40 70 50
Montgomery 70 86 69 85 68 / 40 60 40 70 50
Troy 68 85 68 84 68 / 50 70 40 70 50
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
75/58/32/08
Area Forecast Discussion
National Weather Service Columbia SC
1051 PM EDT Wed May 23 2018
.SYNOPSIS...
The region will remain moist and unstable the next few days
between a ridge offshore and weak low pressure to the west.
Scattered to numerous showers and thunderstorms mainly during
the afternoon and evening expected over the next few days.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Showers have mostly dissipated with a few cells along
intersecting outflow boundaries and a few thunderstorms along
the boundary just north of the forecast area. Overnight expect
some showers and possibly a thunderstorm to develop along the
boundary as well as the southern CSRA where outflows will
persist from current convection. Other concern will again be
potential for early morning fog. Have remained with patchy fog
in the forecast as uncertainty remains with the boundary moving
into the northern Midlands and outflow in the southern Midlands
and CSRA. Overnight lows will be around 70.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
A weak front and drier air aloft will move into the forecast area
(FA) from the north Thursday. Deep, moist flow from the SE and
surface-based forcing along the boundary will result in moderate
instability and trigger showers and thunderstorms in the afternoon.
Expect slow storm movement given weak mean wind speeds, increasing
the threat for localized heavy rainfall and flooding. Particularly
in areas that have already received heavy rainfall in the past few
days. Small hail will also be possible with drier mid level air
impinging from the north. Max temperatures will be in in the low to
mid 80s and lows in the upper 60s and near 70.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A moist airmass will remain over the region, with similar conditions
as previous few days. Convection will mainly be diurnally driven
through Saturday with moderate rain from scattered showers and
thunderstorms likely each afternoon. Sunday through Wednesday,
models are in good agreement that there will be a 500 mb trough to
the west, driving a tropical plume of moisture into the Southeast.
PWAT values in the GFS and ECMWF are well above normal or near
record during the time period. There is at least a high chance of
moderate rainfall during the period with heavy rainfall possible at
times.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
The moist air mass will remain through the TAF period. The high
moisture combined with nocturnal cooling and convergence
associated with a weak front sinking southward should result in
widespread IFR development tonight as indicated by most of the
guidance. Followed the GFS LAMP for the timing. The high
moisture and convergence may help support showers or thunderstorms
overnight but expect little coverage because of nocturnal
cooling. The HRRR displayed little coverage. The chance was too
low to include in the terminal forecasts. The front in the
region will slow improvement Thursday morning but expect diurnal
heating and mixing will eventually lead to MVFR conditions
later in the morning. Heating combined with high moisture and
the front in the region should result in widespread showers and
scattered thunderstorms later during the day and expect mainly
MVFR conditions as indicated by the NAM MOS. IFR conditions will
likely occur at times in heavy showers and possible thunderstorms.
However, did not include the more pessimistic conditions in the
terminal forecasts at this time because of timing uncertainty.
EXTENDED AVIATION OUTLOOK...Late night and early morning IFR to
MVFR ceilings and visibilities along with mainly diurnal
showers and thunderstorms through early next week as a very
moist air mass remains over the region.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Charleston SC
1011 PM EDT Wed May 23 2018
.SYNOPSIS...
High pressure will remain to the east through Friday while a
trough of low pressure lingers to the west. Developing low
pressure over the Gulf of Mexico will slowly move north toward
the central Gulf Coast this weekend, possibly lingering through
early next week. This pattern will maintain higher than normal
rain chances across the area.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A mid level perturbation will linger over central and south-
central Georgia, while an MCV which has been evident on radar
and the HRRR will also be situated in a similar position through
the overnight. These features along with modest low level
moisture convergence, lingering surface outflow boundaries and
weak upper difluence will allow for isolated to scattered
showers and a few t-storms to linger through overnight, mainly
across Georgia to the south and west of Savannah. Pockets of fog
can certainly occur late in locations where earlier rains
occurred and the convective debris clouds diminish. But
probabilities are not high enough to include adding to the
forecast.
Previous discussion... Boundary interactions and deep moisture
convergence, aided by some upper difluence and weak PVA will
continue to allow for scattered convection, mainly to the W and
SW of Beaufort and Savannah. Although the overall thermodynamics
are unimpressive, all of the Hi-Res models show that convection
south of the Altamaha River will move in during the mid evening
and could last through the late evening or in some capacity
even after midnight. Heavy rains are the main weather hazard
given weak storm flow and excessive moisture where PWat is near
160% of normal.
There are no strong indications of anything more than ground fog
or patches of low stratus late tonight, so no need to mention in
the forecast.
Other than hourly temp adjustments to account for the convection,
it`ll be another warm and humid night with persistence the best
forecast in regards to low temps.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Thursday into Saturday look to continue the wetter than normal
pattern due to a weakness in the upper ridge over the area and
an inland surface trough, along with a tropical airmass.
Conditions will be more favorable for convective initiation
inland, closer to the surface trough and upper shortwave,
especially during the daytime hours. We continue to show high
end chance to likely PoPs across inland areas during the daytime
periods, with chance PoPs elsewhere. Given fairly weak
instability we are only showing isolated thunderstorms. No
significant flooding or severe weather is anticipated at this
time. Temperatures will generally be near to above normal,
especially lows.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Not much pattern change late this week into early next week with
high pressure remaining to the east and low pressure over the Gulf
of Mexico moving north, most likely toward the north-central Gulf
Coast. The low could stall out near the Gulf Coast into early next
week. This pattern will mean the tropical air mass will remain in
place across southeast SC/GA leading to the continuation of higher
than normal rain chances, especially each afternoon/evening.
Temperatures should generally stay near to above normal.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
KSAV: Mainly VFR. But nonetheless keeping a close watch on
convection far to the SW of the terminal which will approach
during the late evening. In all likelihood it will fall apart
before reaching the airfield. Only small chances of flight
restrictions in ground fog/stratus late tonight/early Thursday
and again in SHRA/TSRA Thursday afternoon.
KCHS: Mainly VFR. Low risk of flight restrictions in ground
fog/stratus late tonight/early Thursday and again in SHRA/TSRA
Thursday afternoon.
Extended Aviation Outlook: A persistent tropical air mass will
lead to higher than normal rain chances into early next week,
mainly each afternoon. Thunder chances will be low, however,
given the limited instability. Some restrictions will also be
possible from morning low clouds and/or fog.
&&
.MARINE...
Tonight: Winds have been a little slow in veering as quickly as
we were forecasting, but still looking for winds to clock around
to the SW north and S-SW south overnight. Speeds will be as high
as 10-15 kt, dropping off several knots late, with seas
generally 2-4 ft and highest on the outer Georgia waters. There
remains little to no risk for convection through daybreak.
Thursday through Monday: The area will remain between a trough
to the west and high pressure to the east, with generally
onshore flow prevailing. The gradient will tighten slightly
Friday into Saturday, increasing marine winds a bit, especially
the afternoon sea breeze along the coast. Although confidence
remains low, a tropical cyclone could develop in the Gulf of
Mexico over the weekend and move north, enhancing the gradient
and potentially requiring Small Craft Advisories for some
waters late weekend or early next week.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Hastings NE
940 PM CDT Wed May 23 2018
.UPDATE...
Issued at 939 PM CDT Wed May 23 2018
Have refreshed our forecast and Hazardous Weather Outlook (HWOGID)
within the past 30 minutes to reflect our latest thinking for the
overnight hours...
A brief look back:
Late this afternoon/early evening we dealt with a few isolated
severe storms driven primarily by daytime/diurnal heating and
instability (most severe hail reports were from Phillips County
KS). This convection has long since died off, and over the last
few hours the focus for strong/severe activity has focused (as
expected) to our west over western Nebraska.
Rest of tonight:
The vast majority of the CWA (except for perhaps the far western
fringes) should remain storm-free through at least midnight.
However, agree with the previous forecaster that the overnight
hours could feature almost "random" isolated thunderstorm activity
almost anywhere, especially after 3-4 AM, as weak disturbances in
west-southwest flow aloft interact with a modest 30-45kt low level
jet, and with elevated CAPE/instability in the 850-700 millibar
layer averaging roughly 500-1000 J/kg. With deep-layer shear
remaining fairly weak at around 25kt-or-less, am not expecting
organized severe storms, although a few instances of small
hail/gusty winds cannot be ruled out. Although SPC has formally
placed/kept much of the western half of our coverage area (CWA) in
a Marginal Risk through the night, we have geared our local- level
thinking more toward the non-severe side, and this is reflected in
the latest HWO. That being said, we will need to closely monitor
the western NE convection just in case it tries growing upscale
into more of an organized wind threat. Even so, current
radar/short term model trends largely suggest that any organized
severe storm threat overnight should continue to focus at least
slightly west-northwest of our CWA.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 237 PM CDT Wed May 23 2018
Aloft: RAP analyses/WV imagery and 12Z RAOBs show the Rex block
remains over Wrn N America. The low was over ID/WY with SW flow
over the Plns. The Rex block will finally break down over the next
24 hrs...but that does not mean an end to the summer wx. Models
are tightly clustered on the low drifting into MT tonight and into
the Canadian Prairies tomorrow. As this occurs...the flow will
remain SW over the Cntrl Plns...but a trailing trof from the low
will move over the Plns from ND to Wrn KS by 00Z/Fri.
Surface: The CWA was in the warm sector. Low pres was over MT
with a warm front extending SE into the mid-MS Vly. High pres was
over the GtLakes. The rgn will remain in the warm sector thru
tomorrow as the low lifts to Lk Winnipeg. As it does so...a
trailing sfc trof will drift from the lee side of the Rockies into
Cntrl Neb and NW KS... extending from ONL-LXN-CBK.
Now thru mid-evening: Isolated tstms. MLCAPE 1500-2000 J/kg but
0-6 km shear is very weak (20 kt). So expect outflow dominant
ordinary cells.
Tonight: Any evening storms will die shortly after sunset with no
help aloft. With no change in the situation...could small/isolated
shwrs and possibly a tstm or two redevelop after 3 AM...similar to
this morning. Most locations will remain dry.
A mild and muggy night with dwpts in the 60s. Temps will not fall
below 70F until after midnight.
Thu: Possibly similar to this AM with small isolated shwrs
associated with high-based ACCAS. Isolated tstms could develop
along the sfc trof. With temps 87-92F and dwpts in the 60s...
MLCAPE is fcst near 2500 J/kg. 0-6 km shear will be 15-25 kt
across the CWA (lowest E/highest W). Any tstms that develop could
turn svr...but tstm coverage will not be widespread.
Temps similar to today (87-92F).
.LONG TERM...(Thursday night through Wednesday)
Issued at 237 PM CDT Wed May 23 2018
Aloft: The last 2 runs of global models and the EC/GFS ensemble
means are in excellent agreement that the Westerlies will remain
far to the N over Canada thru next Wed. Low-amplitude NW flow will
occur Fri behind Thu`s trof. A ridge will then build over the
Cntrl USA Sat downstream of a low that moves into the Wrn USA and
cuts off over UT. Neb/KS will be on the W side of the ridge with
weak SW flow. Predictability regarding when cut-off`s open up or
become mobile is low...but present indications are that a trof
approaching the W coast could force the low to lift into the Nrn
Rckys Tue and the Nrn Plns Wed as a remnant trof. The tail end of
this trof could affect the CWA.
Surface: Very weak high pres will build over the Cntrl Plns Fri-
Sat. It is then fcst to drift E of the rgn Sun. A large high will
sink from Canada into the GtLakes Mon-Wed. This scenario will
maintain Multiple days of return flow.
Temps: The heat is on. Welcome to an early summer. Widespread
low-mid 90s Fri-Mon...then possibly cooling back into the 80s-low
90s Tue-Wed as heights fall a bit.
Precip: Mostly dry. There will be the typical isolated tstms that
fire daily well to the W within the lee trof. The weak flow and
lack of forcing will keep nearly all of it well to the W of the
CWA...but can`t completely rule out a rogue storm or two making it
to areas W of Hwy 183. If the upr trof moves thru here Tue or Wed
that would increase the risk of sct tstms.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 730 PM CDT Wed May 23 2018
General overview/thunderstorm chances:
VFR ceiling/visibility expected to prevail, with only varying
amounts of mid-high level cloud cover. As for rain/thunderstorm
chances, they are not "zero", especially late tonight into
Thursday morning, but these chances currently appear small enough
that even a generic "vicinity thunderstorm" (VCTS) mention cannot
really be justified. There may also be somewhat better
thunderstorm chances just beyond this valid period Thursday
evening.
Winds:
Turning to surface winds (and assuming no thunderstorm
influences), they will remain fairly consistent from a southerly
direction through the period. Sustained speeds will average
10-15KT through most of the period, with the overall-strongest
speeds featuring gusts 20-25kt occurring Thursday afternoon.
Looking just above the surface, have maintained a mention of low
level wind shear (LLWS) from later this evening through early
Thursday morning, but it currently appears somewhat marginal for
TAF inclusion. Nonetheless, the presence of southerly winds within
the lowest 1,000 ft. increasing to around 40kt could result in
roughly 30kt of shear magnitude between the surface and this
level.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Pfannkuch
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Gray ME
927 PM EDT Wed May 23 2018
.SYNOPSIS...
A cold front will exit the region this evening, allowing showers
and thunderstorms across portions of Maine to move offshore.
A warm front will approach the region Thursday before crossing
the region Thursday night. This will lead to very warm
conditions on Friday. A backdoor cold front drops into the
region this weekend and will likely provide for some unsettled
weather.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
---920pm Update---
Scattered clouds moving across the CWA this evening. An area of
cooler tops on satellite coming off the mountains and headed toward
the midcoast. High resolution short range models are picking up on
this feature and have increased clouds over the midcoast over the
next six hours or so. Another trend that is showing up is that the
temperatures are not falling quite as quickly as the models were
originally suggesting. This could turn out to be a fairly large issue.
If temperatures stay 5F to 7F degrees warmer than expected over
most of New Hampshire and interior Maine, then the relative humidity
recovery will not be as good tonight. With extremely dry air in place,
we were already expecting minimum relative humidity values tomorrow
in those locations to be 20 to 30 percent. A small error in the
temperatures tonight could lead to RH values tomorrow 5 to 10 percent
lower than originally expected. As of right now, it does not appear
that the winds will be strong enough to meet red flag warning criteria,
but they will not be far away... maybe only 5 to 10 mph shy of red flag
criteria. Will issue an SPS for fire conditions with this update for
tomorrow to get the word out.
---630pm Update---
Showers and thunderstorms have now completely fallen apart across
the area. Will update the forecast to remove mention of
precipitation tonight. Also, the winds have now shifted to the
north across the forecast area and much drier air is streaming
in. This should make for a more comfortable airmass over the
next few hours.
.Previous Discussion...
HRRR continues to have a very good handle on the ongoing
convection. The precipitation will slip off the coast over
the next hour or two and diminish. A northwest breeze will
follow drying conditions out across the region. There is still
the possibility of light patchy fog however in the Penobscot
River Valley where the heaviest precipitation fell today.
Cold air advection will continue overnight. This will allow for
readings to fall through the 40s with upper 30s likely in the
mountains.
&&
.SHORT TERM /3 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
On Thursday a warm front will approach the region from the west.
This will cross the region Thursday night with an increasing
gradient and strong warm air advection above the surface during
the overnight hours. The front will be relatively moisture
starved. This system will be the leading edge of much warmer
air to follow for late in the work week.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
A warm westerly flow will send temperatures soaring on Friday as
high pressure remains south of the region. Expect most of the
region to range through the 80s and will even approach 90 in far
southern New Hampshire. A back door cold front will bring
increasing clouds and a chance of late day showers into far
northeast zones but the remainder of the forecast area will see
a dry day.
Cold front will sag south into northern zones Friday night and
will be the focus for continued shower activity in central and
northern sections of Maine and New Hampshire. Lows overnight
will range from the mid 50s north to the mid 60s south.
Cold front will continue to push south through the region on
Saturday and will end up stalled over southern New England by
late in the day. Looking for occasional showers and perhaps an
afternoon thunderstorm in southern zones. Highs will range from
the upper 60s to mid 70s north and will range through the 80s in
the south.
High pressure building in from the northeast Saturday night
will set up an increasing onshore flow bringing ocean stratus
into southern New Hampshire and southwest Maine. Looking for
occasional showers with lows in the mid 40s to mid 50s.
Although the sun angle is reaching its highest point
considerable high and mid level clouds may prevent this low
level moisture from burning off in inland locations on Sunday.
Occasional showers will again dampen the holiday weekend. Highs
will generally remain in the 50s across western Maine and lower
to mid 60s in New Hampshire.
Low level moisture will invade most of the forecast area Sunday
night and Monday along will a continuing chance of showers. Weak
shortwave moving in from the west on Monday will enhance shower
activity across the region. Highs on Monday will range from the
upper 50s to upper 60s. A weak cold front behind the departing
shortwave will push south into northern zones Monday night and
will continue south and offshore by early afternoon on Tuesday
bringing sunshine and warmer temps back into the region.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
Short Term...VFR conditions expected tonight through Thursday
night. However, there will be some patchy inland valley fog over
eastern areas tonight with localized MVFR or IFR conditions
along and near the Penobscot River Valley.
Long Term...
VFR Friday and Saturday. Areas of IFR/LIFR ceilings developing
in southern zones Saturday night and Sunday. Widespread IFR/LIFR
ceilings developing Sunday night and persisting through Monday
night.
&&
.MARINE...
Short Term...Winds will be relatively light tonight and
Thursday. However, the gradient will increase with the passage
of a warm front Thursday night. Winds will likely exceed SCA
thresholds at that time.
Long Term...
SCA`s likely on Friday.
&&
.FIRE WEATHER...
On Thursday, RH values will fall into the 20 to 25% range across
most of the area away from the coast. Occasionally gusty winds
will create an elevated fire danger.
Friday will see gusty west to northwesterly flow around 25 kt.
These winds will help to mix down dry air from aloft with RH
dropping to around 30 to 40% across southern New Hampshire and
possibly portions of southwestern Maine. This will put southern
NH near Red Flag criteria and will need to be watched for
possible Fire Wx headlines.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
Pohl
Area Forecast Discussion
National Weather Service Wilmington NC
904 PM EDT Wed May 23 2018
.SYNOPSIS...
A weak cold front approaching from the north will produce a
continued low chance for showers and thunderstorms late this
evening and overnight. The front across or just south of the
local area will dissipate during Friday. Low pressure
developing across the Gulf of Mexico will bring tropical
moisture northward and help fuel a higher probability of showers
and thunderstorms with heavy rain across the eastern Carolinas
Sunday and into early next week.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 845 PM Wednesday...The diurnally induced convection across
the FA is waning fast at the moment and is nearly gone. Have
lowered POPs to chance or slight chance for the remainder of
this evening as a result. However, HRRR model runs indicate
that as the sfc cold front drops further south and across the FA
toward daybreak, showers and or tstorms could re-develop given
a better convergence zone for initiation. As a result, have
kept the 20-30 POPs going thruout the night. Some tweaks to
overnight mins and Hrly temps and dewpts based on trends with no
categorical changes.
Previous.......................................................
As of 300 PM Wednesday...A mid-level disturbance along the
Savannah River surrounded by very light steering flow should
move very little over the next 24 hours. Surface high pressure
moving across the Great Lakes will nudge a surface cold front
southward across North Carolina tonight, stalling out across
eastern South Carolina on Thursday. This should be the focus
for another day of showers and thunderstorms.
Today`s thunderstorm activity is developing along multiple
east-west oriented convergence boundaries where the airmass is
uncapped with CAPE of 1500-2500 J/kg. Convective organization
has remained minimal due to very weak wind shear: bulk shear
across the 0-6 km layer is only 10-20 kt. SPC`s marginal severe
weather threat across northeastern NC and southeastern VA is
keyed to the stronger shear and potential for more significant
storm cell organization that exists there.
Convective activity should diminish this evening, however
most recent runs of the synoptic and rapid update models show
convection lingering through the night along the south end of
the higher shear zone across North Carolina, particularly as the
cold front eases its way south overnight and increases low-
level convergence. A relative minimum in convection should occur
Thursday morning, with showers and storms reblossoming Thursday
afternoon mainly across South Carolina near the stalled front
and pooled low-level moisture. Forecast PoPs are as high as 70
percent in the Florence vicinity Thursday afternoon.
Lows tonight should range from 68-71. Highs Thursday are
forecast to reach 80 on the beaches to around 84 inland.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 3 PM Wednesday...Weak upper low across GA Thursday night
will drift northward and weaken further across the far western
Carolinas during Friday. In addition, the H5 ridge situated off
the coast will help direct moisture plume back into the
Carolinas and precipitable water will increase during the day in
response. Expect the best convective coverage to be across the
SC zones initially during Friday, then in the LBT zone group
later in the day. During Friday the residual foot print of the
old front will drift northward and finally become absorbed in
the broader scale flow and awash in the sea breeze circulation.
Favor a blend of MAV/MET numbers through the period which
suggests near climatology high temperatures Friday and warmer
than normal low temperatures each night.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 3 PM Wednesday...A return to a very wet period appears to
be in order for the extended time frame. A ridge of high
pressure will weaken and the trough will open up across the
eastern half of the United States. The models continue to show a
low developing over the Gulf either as a subtropical or
tropical system. For our area this means we should expect to see
increased moisture and the chance of heavy rain. The models
continue to show a surface low developing over the Gulf of
Mexico, the 12Z ECMWF shows the low moving northward to
Louisiana and slowing off the coast on Tuesday. The GFS is near
the Florida peninsula and the Canadian is in middle. With the
recent rains flood watches may be required Sunday into early
next week.
With cloud cover and rain chances high temperatures are expected
to remain in the middle 80s and lows should be range from 68 to
73 through the period.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
As of 23Z...Convection approaching KFLO and KLBT has been
weakening and will continue until dissipating after sunset. Weak
frontal boundary will drop south overnight and result in a wind
shift early Thursday. Scattered convection is expected to
develop early Thursday afternoon along and south of the front.
Extended Outlook...Brief/local IFR visibility is possible in
thunderstorms Thursday afternoon. Tropical moisture returning to
the area Sunday and Monday could bring more widespread
thunderstorms with periods of IFR ceilings/visibility possible.
&&
.MARINE...
NEAR TERM /THROUGH THURSDAY/...
As of 845 PM Wednesday...Winds ahead of sfc cold front dropping
southward, will drop to 5 to 10 kt with the sfc pg ahead of it
becoming quite relaxed. By daybreak, the cold front`s position
will be near Cape Fear. This front will continue to push
southward and by midday will likely stall just out of the ILM
waters. Have continued the brief veering trend with winds until
it`s final direction of NE-ENE is established. Could see
isolated convection along and ahead of the cold front dropping
southward during this overnight period. Significant seas will
run 2 to 3 ft, with only a few 4 footers possible from Cape Fear
northward. The 8 to 9 second period SE Ground swell will
continue to dominate the overall seas with the higher producing
wave energy via spectral density plots from NDBC.
Previous.........................................................
As of 300 PM Wednesday...High pressure pushing east across the
Great Lakes will ease a cold front southward through North
Carolina tonight. The front should reach the Cape Fear area
shortly after sunrise Thursday, with the boundary slipping south
along the Grand Strand between 8-11 AM. Southwesterly winds
ahead of the front should turn northeasterly behind the front,
but with no significant increase in wind speed expected.
Scattered showers and thunderstorms should end early this
evening south of Cape Fear but may continue overnight north of
Cape Fear. Showers/storms should develop again Thursday
afternoon, mainly south of Cape Fear. Seas currently around 3
feet should diminish by about a foot with lighter wind speeds on
Thursday.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 3 PM Wednesday...Onshore flow around 10 knots expected
Thursday night with seas less than 3 ft. As high pressure off
the Southeast U.S. becomes better established the flow will veer
to a southerly wind by Friday night. Chance of showers and
thunderstorms across the waters, more-so during Friday and
Friday night. Seas 3 ft or less expected Friday and Friday
night.
LONG TERM /SATURDAY THROUGH MONDAY/...
As of 300 PM Wednesday...As high pressure off the coast shifts
eastward and a trough of low pressure exists over the east half
of the United States, the winds will be from the south-
southeast to south-southwest at 10 to 15 knots. This extended
period of fetch will see the seas rising from around 2 to 3 feet
on Saturday to 4 to 6 feet by late in the day on Monday, when a
small craft advisory may be needed.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/TRA
SHORT TERM...SRP
LONG TERM...DRH
AVIATION...CRM
Area Forecast Discussion
National Weather Service Lubbock TX
620 PM CDT Wed May 23 2018
.UPDATE...
Update to raise PoPs to likelies west of Highway 385 this evening,
while lowering values elsewhere. Also inserted heavy rain mention
across our western zones this evening for PWATs of 1 to 1.2
inches collocated with weak steering winds.
Regional radar and satellite reveal a consolidating line of
storms across western Lea County early this evening. Although
favorable storm relative inflow and instability exist, mid level
winds are largely anemic. This will be a major deterrent for
significant eastward propagation of convection, with most of this
process relying on outflow mechanics. Recent iterations of the
HRRR indicate such a scenario this evening with a marked decay of
convection expected after sunset with increasingly hostile CINH
across the eastern South Plains. Window for severe modes should
be small and confined mostly to our counties adjacent to the NM
border.
&&
.PREV DISCUSSION... /issued 550 PM CDT Wed May 23 2018/
AVIATION...
Thunderstorm activity across eastern NM has slowly been expanding
eastward toward West Texas. There is a risk of some of this
activity accelerating eastward during the evening hours though
confidence in reaching KPVW/KLBB remains too low for mention at
this time. Otherwise, VFR is expected outside of convection.
PREV DISCUSSION... /issued 223 PM CDT Wed May 23 2018/
DISCUSSION...
Mostly elevated convection has developed across sections of
eastern New Mexico already this afternoon, the southern bit
already petering out as it crosses into the northwestern part of
the forecast area while scattered storms south of Clayton to near
Dalhart are having a better go at it. Hi-res models are again more
generous with QPF this evening than the WRF-NAM and GFS, although
that hasn`t been a good thing of late. Favored area for initiation
by the models is Eddy and Lea counties in New Mexico with some
form of eastward movement. That area was populated by stratus this
morning and is taking some time to warm up but do appear to be
nearing convective temperatures. Convection is also developing on
the Sacramentos and Guadalupes and may be a player again for areas
near the state line late tonight. Any storms that form eastern New
Mexico and migrate into the forecast area late afternoon/early
evening will have a chance to become marginally severe. CAPE is
healthier than yesterday, on the order of 2000 J/kg, which may
give that convection a better chance to develop than yesterday`s
as well. However, shear remains the limiting factor as far as
severe potential goes with 0-6 km bulk shear values on the order
of 20 kts. Will continue with chance PoP`s for the western half of
the forecast area for tonight tapering to slight chance east.
Precip chances take diminish after tonight as upper level ridging
is still progged to develop over the forecast area, the axis being
overhead Friday and Saturday. Could see some isolated storms
develop Thursday afternoon under the building ridge, but a
stronger ridge and veering low level flow should for the most part
squash storm potential Friday and Saturday. Storm chances could
return for Sunday through Tuesday an upper low moves out of the
Great Basin onto the central Plains breaking down the upper ridge
and backing the low level flow across the forecast area.
Temperatures are still expected to push the century mark this
weekend in response to the building upper ridge.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
93
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1037 PM CDT Wed May 23 2018
.SHORT TERM...(This evening through Thursday)
Issued at 313 PM CDT Wed May 23 2018
As of this afternoon, the upper level ridge axis is nearly overhead
with a couple subtle waves expected to lift northeast from the
upstream trough across the western CONUS. Deep southerly flow has
brought increased moisture north, with dew points in the area now in
the mid 60s. This is the beginning of the trend to warmer and more
humid weather to come.
A very slow moving area of showers and thunderstorms across western
MN has decayed as it`s moved east, but not before sending an outflow
boundary southward. A few brief thunderstorms have been able to
initiate along the boundary, which has now essentially stalled out
just north of the Iowa border. Don`t expect these storms to
maintain themselves as they run northeast of the best instability.
Speaking of, ample warmth and moisture has pooled to the west, with
3-4k j/kg of MU CAPE across portions of eastern South Dakota and
Nebraska. For tonight, expecting our forecast area to be primarily
dry, but an isolated shower or storm can`t be ruled out.
Undoubtedly, the main activity will be to our west and north. Even
though instability is lacking to our north, the upper level
shortwave will continue northeast from the Dakotas, bringing some
lift to northern MN, so rain chances are much better there.
The latest HRRR solution for the overnight period seems to have a
reasonable expectation of storms continuing overnight across eastern
South Dakota near the nose of the low level jet with a gradual
progressing eastward by tomorrow morning. Did include some chance
PoPs across western MN for tomorrow morning to account for the
possibility of the storm remnants moving in tomorrow morning.
A warmer day is in store for us tomorrow and the upper ridge will
shift slightly east. SPC has continued a slight risk for western
MN, which makes sense given the 3-5 k j/Kg CAPE, but marginal to
weak shear environment. With additional upper level waves moving
northeast along the backside of the ridge, do expect some
thunderstorms to be set off tomorrow afternoon into the evening
across western MN. Similar to what is occurring now in Nebraska and
South Dakota, expect some severe hail potential given the large
amount of instability. However, expect these storms pulse up and
down during the afternoon. Wind damage could be possible with a
few storms if strong cold pools develop.
.LONG TERM...(Thursday night through Wednesday)
Issued at 313 PM CDT Wed May 23 2018
The low-level jet of 25 kts and near 1200-1700 J/kg of MLCAPE will
allow convection to be ongoing during the early overnight hours into
Friday. The eastward progressing storms are expected to weaken by
mid- Friday morning with increasing CIN.
The upper-level shortwave trough and surface cold front will
continue progressing eastward through Eastern MN and Western WI on
Friday. Mostly sunny skies over Western WI will allow temperatures
to warm in the upper 80s and lower 90s on the Buffalo Ridge. Remnant
outflow boundaries as well as the main boundary along the cold front
will be the sources of lift for afternoon convection over Eastern
MN and Western WI. Shear does not appear to be high with only
about 15- 20 kt bulk shear, so there is only a marginal severe
threat forecast.
Upper level ridging will commence on Saturday. As mentioned in the
previous long-term discussion, the GFS hints at a "dirty ridge" with
the 12Z GFS pushing a shortwave across MN on Sunday into Monday. The
grids indicate slight chances for precipitation, but PoPs may be
eliminated in the days to come if other guidance continue to show
dry conditions. The ECMWF is one of the models that indicate dry
conditions though the remainder of Memorial Day weekend before
advecting cyclonic vorticity on Tuesday. This may potentially
bring rain chances on Tuesday to Western MN but confidence is low.
Thus, left chance PoPs in the forecast for Tuesday. Otherwise,
the next best chance for precipitation looks to be Wednesday with
both the GFS and ECMWF both indicating a short-wave traveling
through the CWA.
Besides rain and storm chances, the other main concern over the long-
term period will be the heat. High temperatures are expected to be
widespread in the upper 80s to lower 90s Saturday through Monday
with the Buffalo Ridge likely reaching into the mid 90s. There is
expected to be an increasing humidity trend throughout the Memorial
Day weekend, so Sunday and Monday will likely be the muggiest
days.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1037 PM CDT Wed May 23 2018
Scattered showers and thunderstorms continue near AXN, which
should wane in the next couple hours. Broken mid or high level
clouds are shrouding the rest of the region. Mostly dry conditions
are expected through Thursday morning, but some storms are likely
to develop across MN Thursday afternoon, spreading east to WI
Thursday evening.
KMSP...No concerns tonight.
/OUTLOOK FOR KMSP/
FRI...Mainly VFR. Chc TSRA. Wind SW 5-10 kts.
SAT...VFR. Wind WSW 5-10 kts.
SUN...VFR. Wind W 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...SPD
LONG TERM...AMK
AVIATION...BORGHOFF
Area Forecast Discussion
National Weather Service Omaha/Valley NE
737 PM CDT Wed May 23 2018
.SHORT TERM...(Tonight through Saturday)
Issued at 332 PM CDT Wed May 23 2018
Thunderstorm chances tonight and especially Thursday afternoon and
evening are the primary forecast concerns.
Showers and thunderstorms that had pretty much dissipated this
morning in central Nebraska had reformed this afternoon along mid
level theta-e axis working into northeast Nebraska. Hi-res model
output had not captured this activity in afternoon hourly runs.
Storms are expected to continue tracking north-northeast this
afternoon, and may linger in parts of northeast Nebraska during the
evening before dissipating with loss of daytime heating.
Second area of convection is possible late today and this evening,
tied to weak mid level impulse lifting northeast from western NE/KS
shown on water vapor satellite imagery and RAP 500mb analysis. Hi-
res models were becoming more insistent on scattered storms
developing in northwest Kansas and south central Nebraska, and
tracking activity into our western CWA this evening. While shear is
weak, modest instability should support storms through sunset before
diminishing.
Both these areas of storms are in an environment with weak shear,
but instability on the order of 2000-2500 J/kg of MLCAPE may aid
in low-end severe hail potential.
Attention then turns to later tonight when low level jet increases
to near 40kt from central into northeast Nebraska under southwest
mid level flow regime. Nose of that jet is forecast over north
central and northeast Nebraska between 06Z and 12Z in area where
MUCAPE increases to 1500 J/kg based on NAM forecast soundings.
Expect scattered convection to fire by 09Z and gradually work north
and northeast through northeast Nebraska through mid morning.
A lull in the action is likely a few hours either side of 18Z
Thursday, allowing atmosphere to recharge from central into
northeast Nebraska. Models suggest surface dew points in the mid
and upper 60s combined with cooling mid level temperatures with
approach of shortwave will push MLCAPE values potentially north of
3000 J/kg. Bulk shear looks modest at best, maybe around 25kt
0-6km, and low level convergence appears to lag instability. SPC
has elevated our severe risk into the Slight category, and given
instability, think that is reasonable if storms fire in our CWA.
Convection is expected to continue much of the night Thursday night
as shortwave gradually works through eastern Nebraska and southwest
Iowa by Friday morning. Storms may linger a while longer in
southeast Nebraska and southwest Iowa, and could re-fire Friday
afternoon if instability is not swept southeast as per latest GFS
indications.
Otherwise a mainly warm forecast is in order as 850 temps climb into
the lower and middle 20`s C range for Friday and Saturday. Many
spots should reach 90 one or both of those days.
.LONG TERM...(Saturday night through Wednesday)
Issued at 332 PM CDT Wed May 23 2018
A fairly active setup appears to be forming for next week, at least
in terms of chances for thunderstorms. Potential severity of
convection will have to be determined at a later time, but it
looks like we`ll have chances for storms much of the period
Monday through Wednesday.
Upper low moving through the western U.S. on Sunday will eventually
open up and send several impulses through the Plains, with the
timing of each impossible to time this far out as solutions are
widely variable between model to model and run to run. However low
level southerly flow should maintain a moist and warm atmosphere
conducive for convection with each impulse.
As far as temperatures are concerned, Sunday looks like the warmest
day of the long term period under mid level ridging ahead of
approaching low. Monday through Wednesday temperatures should
average 85 to 90, but could vary based on convection and cloud cover
day to day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 728 PM CDT Wed May 23 2018
Isolated thunderstorms over northeast Nebraska to the west of KOFK
at the start of the period are located on the eastern edge of
instability axis in place across the west half of the state.
This instability pocket is forecast to shift east by the end of
the period with an increasing chance of storms at TAF sites.
VFR conditions will prevail outside of convective areas during the
period with more widespread convection likely after 18Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...Fobert
Area Forecast Discussion
National Weather Service Pocatello ID
206 PM MDT Wed May 23 2018
.SHORT TERM...The low pressure disturbance is moving into Montana
this afternoon. The main area of precipitation is roughly from
Howe to Spencer, Osgood, and Driggs with radar showing a
decreasing area the past hour or two. Isolated thunderstorms have
developed between Hailey and Howe, also between Oakley and
Rockland where the sun has broken through for some afternoon
heating. By Thursday morning we will see showers linger in the
Central Mountains and along the Montana line as a ridge of high
pressure builds quickly ahead of the next round of weather.
Southerly winds will push temperatures back to the 70s and lower
80s Thursday and Friday. By Saturday, the next closed low pressure
disturbance will cross California into the Great Basin. Current
models are similar in timing, but this disturbance looks a bit
removed from the upper level flow pattern and may stall a bit over
Nevada and Utah. RS
.LONG TERM...Sat night through next Wed night. By Memorial Day (Mon)
the eastern Pacific upper level longwave trough has slid farther
north, leaving much of the U.S. West under weak and variable flow.
Thus there is low confidence in the forecast starting Memorial Day.
Such a pattern does allow subtropical moisture this far north
easily. This would mean mild overnight lows, and if the wind is from
the south, warmer than normal highs. Certainly any subtropical
moisture will mean also unstable air and a threat of afternoon
thunderstorms and rain showers. The lack of any organized front
should keep wind light, outside of thunderstorms. The ECMWF and the
GFS both have a closed low moving through Great Basin in different
locations, with the ECMWF sometimes stationary. But on Mon night
this closed low lifts directly over the forecast area heading nearly
northward. So by late night Mon/Tue morning, the precipitation
decreases significantly from what we will be receiving prior to this
point. Showers and thunderstorms do continue though for Tue
afternoon/evening. By Wed afternoon, a will organized upper level
trough is moving into western Idaho, bringing showers and
thunderstorms with it. Through it all, the GFS has considerably more
precipitation, compared to the ECMWF. Have attempted to compromise
between these two product suites, but even the location of heaviest
rainfall is at times nowhere near what the other guidance says. So
painted with a very broad brush. Messick
&&
.FIRE WEATHER...Low pressure over the region will produce scattered
showers and thunderstorms through Thursday. Gusty erratic winds and
small hail are likely near thunderstorms. May see widespread
coverage today across much of northeast Idaho along the upper Snake
Highlands and perhaps into the upper Snake Plain. Friday may be dry
before another system arrives for the weekend.
Valle
&&
.AVIATION...Abundant rainfall today continues through the early
evening. It has brought with it some marginal VFR at two airdromes,
where it has been raining since last night, KIDA and KDIJ. Skies
will clear from west to east, and so KIDA will improve earlier. KDIJ
is likely not to clear much at all, as it already has had close to
half an inch of precipitation since 23/06Z. Expect stratus and BR to
be a problem there tonight. Vertical height-time cross sections have
the increase in surface humidity around 24/12Z, and the NAM output
reduces visibility to the 1SM range, and it all seems plausible.
Elsewhere, TSRA should develop this afternoon, but HRRR guidance
does not present any sort of boundary that develops and pushes
through. This could give some accuracy in timing, but without it, am
pretty much limited to VCTS remarks so that the airdromes are not
shut down for the entire afternoon and early evening. KBYI is the
least affected, and may receive no rain this afternoon. Mid- to low
level moisture appears to continue at KSUN, and so the CIG will
continue during the overnight and into Thu afternoon. TSRA activity
for Thu afternoon/evening should be much less at KSUN and the three
valley airdromes, but actually higher at KDIJ as skies will be
clearer and more heating generates strong instability. Messick
&&
.HYDROLOGY...The past 24 hours there is a pretty good size area
that includes Rexburg, Ashton, Ririe, Driggs, and Antelope Flat
that received .75 to 1.40 inches of rain. a Flood Advisory was
issued for the Teton River at St. Anthony and a Flood Watch was
issued for the henry`s Fork River near Rexburg. It may take a few
hours before the impact of rain and runoff is felt. There is some
uncertainty about how much rain is yet to fall through the
afternoon hours. Some smaller creeks and streams could run swift
tonight and Thursday. Total observed rainfall in the area of the
Big Wood at Hailey has been much less than anticipated and impacts
should be minimal. RS
&&
.PIH WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
757 PM MDT Wed May 23 2018
.UPDATE...
Issued at 757 PM MDT Wed May 23 2018
Updated to allow the red flag warning for the San Luis Valley
to expire at 8 pm.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 307 PM MDT Wed May 23 2018
Thunderstorms will continue to generate along and east of the
surface trof axis across the southeast plains through this evening.
To the east of this axis which roughly runs from KTAD to KLHX to
KLIC, dew points will run in the 40s to around 50 with MLCape values
up to 2000 j/kg per SPC MesoAnalysis. Deep layer shears are running
on the light side for organized severe thunderstorms, generally in
the 20-30 kt range, but given the sufficient CAPE a strong to severe
storm or two will be possible across the far eastern plains through
the evening. HRRR runs continue to suggest activity will be very
isolated in coverage with Kiowa county having the best chance. To
the west of the surface trof axis, dew points have been falling into
the teens and 20s with gusty southwest winds resulting in critical
fire weather conditions across the San Luis Valley. This will
continue through the early evening until winds subside.
With clearing skies and dry surface dew points, tonight should be on
the cool side again across the mountains and valleys and have leaned
temperatures on the low side of guidance. Southeast plains should
see lows in the 50s to around 60. Could be some lingering showers
across the far southeast corner of the plains overnight, though high
res models seem to be backing off on this potential.
For Thursday, it will be dry and hot across the district. Far
southeast plains could see a stray storm or two, but chances look
even lower than today. Dew points will fall off into the teens and
20s across the I-25 corridor westward. This will lead to afternoon
humidity levels below 15 percent. However winds will be lighter so
no additional fire weather highlights expected. -KT
.LONG TERM...(Thursday night through Wednesday)
Issued at 307 PM MDT Wed May 23 2018
Thursday night-Saturday...Upper level ridging continues to build
across the Rockies through the early holiday weekend, as Eastern
Pacific energy translates across the West Coast and develops a
closed upper low across the Great Basin on Saturday. This pattern
supports warm and mainly dry weather, with temperatures expected to
remain well above late spring norms, with highs in the mid 80s to
mid 90s across the lower elevations, and mainly in the 60s and 70s
across the higher terrain. As for precipitation, can`t totally rule
out some high based convection in the afternoon and early evening
hours over the higher terrain, though soundings support mainly virga
and gusty winds.
Sunday-Wednesday...Latest models remain consistent in increasing
southwest flow aloft across the region, as the Great Basin upper
low slowly weakens as it ejects north and west across the Northern
Rockies through early next week. Models do differ on how far east
the system moves before lifting north and west, though generally
this pattern suggests mainly dry, warm and breezy conditions
across the area with temperatures expected to stay above seasonal
levels, in the 80s and 90s across the lower elevations and mainly
60s and 70s across the higher terrain, through the period. Pattern
also leads to increasing fire danger with the potential for
critical fire weather conditions across portions of the South
Central and Southeast Colorado, especially Sunday and Monday.
Pattern also support the potential for strong to severe convection
across the far Southeast Plains Sunday and Monday with possible
dryline interaction, along with better chances of convection
across the eastern mountains and plains into the middle of next
week, as low level moisture increases behind the passing systems
backdoor cold front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 307 PM MDT Wed May 23 2018
VFR conditions expected at the TAF sites over the next 24 hours.
Gusty south to southwest winds will continue until 02z for KCOS,
KPUB and KALS before decreasing overnight. Any isolated
thunderstorms will be well to the east of the KCOS and KPUB
terminals. Thursday will be dry with less wind...though diurnally
driven south to southeast winds are expected in the 10-15 kt range
during the afternoon. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MW
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
Area Forecast Discussion
National Weather Service Blacksburg VA
732 PM EDT Wed May 23 2018
.SYNOPSIS...
A weak cold front slides through the region this evening. High
pressure noses down from the Ohio Valley and Mid Atlantic late
tonight into Thursday, then moves off the coast by Friday.
Warmer air returns on the backside of the high Saturday along
with increasing humidity and the threat for more rain.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 724 PM EDT Wednesday...An already limited convective
threat spatially continues to gradually wane early this evening.
Some scattered storms with brief downpours and gusty outflow
still remain possible through 800 PM in Wilkes and Yadkin
Counties, where moderate instability still exists in proximity
to synoptic cold front. A number of higher-resolution solutions
also point to re- development of scattered showers or storms
from Charlotte County southwest through eastern Pittsylvania and
Caswell Counties over the next hour or two. This potentially
may stem from an outflow boundary now racing northwestward from
earlier severe storms in the Norfolk area. Thunderstorm threat
indicated the most aggressively by the 18z 3-km NAM, which had
handled the earlier storms in central Rockingham County the
best, with some hints of developing in recent runs of the HRRR.
Presently pretty unimpressive thus far in these eastern
counties, but will continue to watch carefully. So all told, I
made some small tweaks to PoPs through 02z to carry scattered
mention of thunder from Charlotte to Caswell Counties, while
tapering PoPs down to all dry elsewhere. Threat of thunder
should end after 02z as boundary layer stabilizes and northerly
flow advects deep- layer dry air from large high over the Ohio
Valley. All areas dry before midnight.
Aforementioned high pressure ridges into the region after
midnight, allowing for northerly winds to slacken. In spite of
dry advection/falling dewpoints, with how wet the ground is,
we should have favorable hydrolapse profiles for patchy fog,
best chance in the western mountains toward sunrise but also
potentially in the Piedmont. Visibility guidance off the NAM and
HRRR don`t suggest the potential but I`m not convinced it`s
recognizing how damp the soils are.
No changes to low temps attm. With drier air, should be a more
comfortable night than experienced recently.
Previous near-term discussion issued at 135 PM follows...
A weak trough moved over the mountains this morning and has
stalled stalled over the foothills this afternoon. Behind this
trough are slightly drier conditions with modest CAPE values
around 1000 J/KG. Under afternoon heading and with an approach
cold front, a few showers and thunderstorms are possible along
and west of the Blue Ridge this afternoon. Ahead of this surface
trough, PWATS are around 1.50 inches and CAPE values 1500-2500
J/KG. As the cold front crosses the mountains this afternoon,
scattered showers and thunderstorms are expected across the
piedmont and along the VA/NC border south. A few of these
showers could become strong to severe and produce heavy
downpours late this afternoon into the evening hours. Since the
ground remains wet, there is a concern for flooding today.
However, steering currents are faster than the past couple of
days and heavy rain from stronger storms should remain brief.
The main threat into this evening will be damaging straight-line
winds and hail. SPC has a marginal risk roughly from a line
east from Buckingham VA south to Reidsville, NC.
Drier air shifts toward the mountains of WV/VA north of
Bluefield to Roanoke this evening then slowly edges southward
overnight, but still some slowness in frontal boundary may keep
the southeast in the soupy airmass one more night. Most of the
convection will wane by midnight. Fog will form in the deeper
valleys by dawn Thursday.
Tonight`s lows will be a touch cooler over the mountains, but
still 10 degrees above normal, from the lower 50s in the
Greenbrier Valley, to mid to upper 50s rest of the mountains,
surging up to around 60 Roanoke to Lynchburg north, and in the
lower to mid 60s southeast to the NC foothills. Highs for
Thursday will be closer to normal with 70s west of the Blue
Ridge to lower 80s east.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 230 PM EDT Wednesday...
Weak residual front well to the south will dissipate by Friday as high
pressure remains in place under shortwave ridging aloft. However a
gradual return to weak southerly flow aloft should bring moisture back
around the surface high espcly southwestern sections by the end of the
week. Per latest model trends looks like any showers Thursday night
will be quite isolated and closer to the NC mountains before expanding
a bit, mainly west of the Blue Ridge Friday, as the flow around
the primary high offshore deepens a bit.
Expect most showers to fade with loss of heating given lack of support
Friday night with increasing coverage across the area from west to east
Saturday with the combination of heating/moisture and deeper southwest
flow. Thus will have likely pops far west Saturday with chances
elsewhere similar to the latest SREF model ensemble. Should again see
things diminish Saturday night with loss of heating, but perhaps
lingering longer into the night with more moisture around so
kept in chance pops for now. High temps mostly upper 70s to mid
80s, except perhaps a little warmer east Saturday under warming
aloft despite possible offset by late day clouds/showers.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 130 PM EDT Wednesday...
Rather wet pattern looks to return through the period as tropical
moisture heads back north ahead of low pressure across parts of
the Gulf states and added weak upper troffiness dropping in
with a surface front to the north. Pending future evolution of
the tropical low to the south, appears will see deepening
south/southeast flow take shape by early next week with an
influx of both Gulf and Atlantic moisture around the rather
large mid level circulation heading out of the Gulf. This should
set the stage for at least more diurnally driven convection
late in the weekend espcly mountains, and across the region
through midweek. However decent surface high pressure building
in from the north next week and potential for more organized
convection to the south may tend to at least slow down northward
expanse of deeper moisture which could mean less coverage at
times. Thus plan to have higher chance to likely pops during
heating and overall lower chances at night unless the core of
the tropical juice ends up farther north/northeast. This could
also mean some heavy rain producers at times given such high
forecast Pwats of better than 1.5 inches. Otherwise will be
turning more humid under varying degrees of clouds with highs
mostly 70s mountains to low 80s east and lows mostly in the
muggy 60s.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
As of 731 PM EDT Wednesday...
Isolated TSRA near the southern Blue Ridge should exist through
01z before trending dry. TAFs should trend VFR, though potential
for at least MVFR mist/fog at Blacksburg, Lewisburg and
Lynchburg between 09-12z. Visibility forecast is of low
confidence given falling dewpoints after midnight, but the
potential for IFR or lower fog isn`t out of the question. More
limited potential for fog development at Danville given enough
northerly flow. Winds north 4-8 kts trend light north to calm by
12z.
Generally VFR at the TAFs on Thursday after early-morning fog
burns off. May be some lingering MVFR ceilings along the
southern Blue Ridge that may obstruct ridges south of Hillsville
to Boone, as moisture begins to return on east-southeast flow.
Winds should veer to east/east-northeast 3-7 kts.
High confidence in ceilings/winds through the TAF period,
moderate to low confidence on overnight visbys in fog. High
confidence in VFR visbys Thursday.
.Extended Aviation Discussion...
VFR Thursday and Friday. Tropical like moisture streams back
north as a warm front moves through Saturday with a return to
showers/storms and potential sub-VFR conditions and heavy rain
thru the holiday weekend.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RCS
NEAR TERM...AL/RCS
SHORT TERM...JH
LONG TERM...JH
AVIATION...AL/RCS
...Update to aviation forecast discussion...
.DISCUSSION...(This evening through Wednesday)
Issued at 613 PM CDT Wed May 23 2018
The overall synoptic pattern will change little over the course
of the next week with well above normal temperatures and periodic
chances for showers and storms.
The early afternoon synoptic setup featured an amplified upper
tropospheric ridge axis centered along the Mississippi River
valley. A Rex Block was in the process of breaking down over the
western CONUS with the weak and complex low over Montana/Wyoming
lifting northward into southern Canada. Broad, weak south to
southwesterly flow could be found over NE Kansas with H850 temps
of +17 to +19 C and surface highs approaching 90 degrees in many
locations. Dewpoints more typical of June and July were in place
owing to an open Gulf, with values in the 60s to low 70s at times.
Isolated showers and storms developed near Emporia midday along a
very weak ribbon of 305-310K isentropic upglide coincident with
1500- 2500 J/kg of MLCAPE and minimal CINH, but given the
negligible deep shear profiles, these pulse storms quickly
collapsed. However, the residual convective perturbations/outflow
boundaries may serve for additional thunderstorm development
throughout the course of the afternoon--waning this evening after
peak heating. However, as with earlier convection, the fact that
winds are 20 kts or less through the entire troposphere will
hinder organization and longevity. A stray downburst would be the
main threat with any storm.
Convection has started redeveloping with a remnant MCV over
Norton and Graham counties in north central KS early this
afternoon. The HRRR has been pegging this development with its
last five runs and tracks it eastward along the KS/NE border
before it decaying at sunset. Have leveraged the time-lagged HRRR
for POPs in the NW this evening to account for this possibility.
As the cutoff low over the western CONUS ejects into SW Canada
tonight, a trailing shortwave drags eastward over the High Plains
on Thursday. A few CAMs maintain some reflection of overnight High
Plains convection into northeast KS Thu morning, but confidence
in this solution is not very high. Additional peak heating showers
and storms are possible Thursday afternoon with a better chance
for storms on Thursday night/Friday morning as a thunderstorm
complex over southern Nebraska advances southeastward with the
upper level trough. As with convection the previous two days, the
lack of deep shear through the column will limit organizational
potential and result in new convection being forced on the
advancing cold pool. There remains a modest amount of MUCAPE in
place and a strengthening LLJ to support convection through the
overnight hours and into Friday morning as the line moves through
NE Kansas. Large hail and potentially gusty winds would be the
main impacts.
As we roll into the holiday weekend, the main theme will be the
continued summertime heat and humidity. H850 temps increase to +20
to +24 C by Friday morning and persist well into next week as a
new cutoff low becomes established over the western CONUS. This
will translate into surface highs in the low 90s throughout the
entire forecast period. Weak southerly flow will sustain the Gulf
moisture plume already anchored over eastern Kansas. Continued
ill-timed chances for pulse showers and storms will also persist
through the weekend, with the next decent chance of a more
organized storm threat not coming until Tuesday night as the
cutoff low devolves into a wave and ejects ENE.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 613 PM CDT Wed May 23 2018
VFR conditions are expected throughout the period. There is still
a chance for some isolated storms to form near terminals tomorrow
afternoon but predictability is too low at this time to include
in this TAF issuance.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Skow
AVIATION...Heller