Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/13/20
Area Forecast Discussion
National Weather Service Caribou ME
916 PM EDT Tue May 12 2020
.SYNOPSIS...
A low pressure system will continue to exit across the
Maritimes overnight. High pressure will build toward the region
Wednesday through Thursday. Low pressure will approach on
Friday then move east of the region Saturday followed by high
pressure for Sunday. Another low from the lower great lakes will
approach on Monday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
9:16 pm update: Latest radar returns indicate that there are
still a few snow showers and flurries in parts of northern and
eastern Aroostook County. Flurries could linger till past
midnight in far eastern Aroostook County. Otherwise, is is
currently mostly cloudy across the northern half of the FA and
clear to partly cloudy to the south. The clouds in the north
will likely begin to break up more toward morning. Temperatures
are already in the 30s in most areas Downeast and the freeze
headlines look good. Made some minor adjustments for the
remainder of the night based on the latest satellite pictures,
radar returns, and observations; but overall the changes were
relatively minor.
Previous discussion:
It was an interesting day across northern Maine with the
coldest early afternoon temperatures ever recorded in Caribou as
the thermometer fell to the upper 20s thanks to low cloud
cover, precipitation, and strong cold advection of a very
anomalously cold air mass over central Quebec. Due to loss of
cloud ice, freezing rain also fell briefly and created a glaze
on elevated surfaces. Water vapor satellite this afternoon shows
two distinct upper level lows, one over the Canadian Maritimes
and another entering southern Quebec. Just ahead of this, a weak
theta-e ridge is noted and has led to a slight moderation of
temperatures over the past hour or so across northern Maine. As
the second upper low moves across the forecast area this
evening, a band of snow will briefly form again over eastern
Aroostook County as noted on the HRRR and hinted at on the RGEM.
Accumulation will be limited to an inch or less. Any lingering
precipitation should end after midnight as the second 500mb
vorticity maxima moves off to the east and drier air advects in
aloft. Temperatures will fall below freezing across nearly the
entire forecast area, except perhaps along the immediate coast.
A rare advection driven freeze warning has been issued for
portions of Downeast Maine where the growing season has begun. A
light to moderate breeze and dry advection should keep
widespread frost from forming.
Skies will clear out for tomorrow with 850mb temperatures of -5
to -10C limiting warming despite the strong May sun. Late
afternoon stratocumulus development is also possible across
northern Maine, so current sky cover forecasts are on the
optimistic side there for the late afternoon.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Wed ngt will likely be the last unseasonably cold ngt as,
finally, the last of historic arctic air masses that has
dominated the Rgn retreats NE toward the Nrn Can Maritimes.
This will allow for additional sig recovery of hi temps on Thu
under msly sunny skies and contd breezy conditions with mixing
of stronger winds from alf from late morning thru mid aftn.
Winds will quickly diminish Thu eve as the sfc ridge crosses the
FA, but increasing hi/mid cldnss from low pres movg E from the
midwest/lower great lks. Shwrs/rn from this system will begin
ovr Wrn areas by Fri morn, but will likely hold off ovr Nrn/Ern
areas til Fri aftn or even evening. Ovrgnt lows will be milder
Thu ngt, with hi temps Fri capped earlier in the day by cld cvr
and rnfl arrival.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Rain will taper off to sct shwrs and then end from late Fri ngt
into Sat morn across the FA. With the dynamics of low weakening
somewhat as it crosses the FA, it appears best rnfl will be
across Cntrl and Downeast areas with a quarter to half inch of
event rnfl indicated there attm, to as little as arnd a tenth
across the far N. Subsequently, highest PoPs in the categorical
range were weighted ovr Cntrl and Downeast areas.
By Sat aftn, skies look to at least partially clr across the FA
with with warmer, even slightly abv normal, hi temps with the
air mass behind the low warmer than the one ahead of it. Sat
ngt and Sun morn also look fair attm. Clds will be on the
increase by Sun aftn with shwrs/rn a good bet for later Sun into
Mon eve as another low approaches from the great lks and tracks
ewrd just S of the FA.
Behind this low, the consensus of long range models indicates
that Tue and Wed look to be fair, with potentially warmer
conditions by Wed.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM:
VFR Downeast. Mainly VFR from KHUL north with brief MVFR
visibility possible in any remaining snow showers late this
evening, then VFR late tonight and Wed. VFR at the Downeast
terminals. NW wind gusts up to 25 knots are expected during the
day Wed.
SHORT TO LONG TERM:
Wed Ngt - Thu Ngt...VFR all TAF sites. Brisk NW winds durg the
day Thu.
Fri - Fri Ngt...MVFR-IFR clgs/vsbys all TAF sites in rn or rn
shwrs. Lgt winds.
Sat - Sun...Mainly VFR all TAF sites with lgt winds.
&&
.MARINE...
NEAR TERM: While a brief break in small craft conditions is
anticipated this evening, the small craft advisory has been
extended until Wednesday afternoon to account for increasing
wind gusts to around 25 knots again after midnight. Seas over
the outer waters of 3 to 5 feet will also continue overnight and
into Wednesday. Winds and seas diminish below small craft later
Wednesday afternoon.
SHORT TO LONG TERM: No definitive SCA pds identified for this
update, although wind gusts and seas may approach attms. Kept
close to blended wv model guidance for fcst wv hts for these
ptns of the fcst. Initially wvs will be composed of a SE
propagating short fetch pd of 3 to 5 sec and a NW propagating
open Atlc background swell Wed ngt and Thu, consolidating to a
single northward propagating 6 to 9 sec wv group by Fri, contg
into the weekend.
&&
.FIRE WEATHER...
Fire concerns will only start becoming a
concern for our FA by Wed aftn as breezy winds and lower aftn
RHs begin to dry the duff later from recent rains and snows.
Relatively low aftn hi temps may also somewhat limit combustion
potential from ignition sources Wed aftn
A better potential for for fire starts will likely occur on
Thursday when breezy NW winds, low aftn RHs, and warmer hi temps
further dry out fine fuels.
We will coordinate any fire wx products with the State of ME
Forest service beginning tomorrow morning based on there
assessment of fire danger attm.
&&
.CLIMATE...
0.3" of snow and freezing rain was observed in Caribou, Maine
today. This brings our monthly snowfall total to 5.9" and makes
it the 3rd snowiest May on record. A total of 151.9" of snow
has been observed for the season, which is good enough for 6th
place. Weather records in Caribou date back to 1940.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Freeze Warning until 8 AM EDT Wednesday for MEZ015>017-029-030.
MARINE...Small Craft Advisory until 2 PM EDT Wednesday for ANZ050>052.
&&
$$
Near Term...CB/MStrauser
Short Term...VJN
Long Term...VJN
Aviation...CB/MStrauser/VJN
Marine...CB/MStrauser/VJN
Fire Weather...VJN
Climate...CB
Area Forecast Discussion
National Weather Service Dodge City KS
605 PM CDT Tue May 12 2020
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Wednesday)
Issued at 349 PM CDT Tue May 12 2020
The persistent cool, cloudy, moist airmass will continue across
southwest Kansas tonight into Wednesday morning before finally
eroding away. Temperatures struggled to get much above the mid 40s
mid afternoon on a continued east-southeast wind. Morning light fog
and drizzle waned late this morning toward the lunch hour but is
expected to redevelop later this evening as low level moist
advection just off the surface increases. Another round of elevated
showers and thunderstorms are expected to develop across south
central Kansas, so we will keep at least some low POPs going across
the far eastern counties adjacent NWS ICT forecast area. The HRRR
and RAP models are fairly aggressive with dense fog development with
a rather large area of model visibility one-quarter mile or less.
The incoming swing shift will need to monitor this closely.
Wednesday will be quite the wild temperature ride for most --
especially far southwest Kansas. A hot, dry airmass will be
replacing the cool, moist airmass over far southwest Kansas, and
these areas will likely see afternoon temperatures some 40-degrees
warmer than this afternoon! The remnant cool, moist airmass will be
slower to erode farther east, and this is where the temperature
forecast will get quite tricky. Some of the latest high-resolution
model solutions, including WRF-ARW, NAM12, and HRRRv4 show central
Kansas stuck in the mid-upper 50s by mid to late afternoon, and
should this pan out, it will really limit the spatial extent of
boundary layer instability for severe local storms. The latest
SWODY2 maintains a 15-percent large hail outlook with 10-percent
hatched area for significant hail potential (two-inch diameter or
larger). Much of late tomorrow/tomorrow evening`s convective event
will be confined to areas south and east of the NWS DDC forecast
area, but the latest thinking is that 3 to 5 of our counties stand a
decent chance for a severe storm or two (perhaps more if the primary
zone for convective initiation shifts farther west). Any severe
weather threat should wane by late evening as storms move east,
deeper into Kansas and Oklahoma. The remainder of Wednesday Night
period looks quiet with south winds remaining in place ahead of
another cold front.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 349 PM CDT Tue May 12 2020
On Thursday, another cold front will push south before slowing down
and eventually stalling out somewhere just south of the NWS DDC
forecast area. Another severe weather risk will exist along this
front, but south of our area across western and central Oklahoma.
Post-frontal upslope will develop later in the evening Thursday, and
this is also likely to support thunderstorm activity across
southeastern Colorado. Any southeastern Co storms in the evening
would move into and/or expand across west central and southwest
Kansas. In fact, the period from late Thursday Night through late
Saturday Night looks convectively-active across the southwest Kansas
region as the quasi-stationary front will remained positioned close
to the Oklahoma-Kansas border. Fairly vigorous surface-based
convection also appears more likely along the boundary, wherever it
sets up, late Friday afternoon/evening. Overall, this pattern is a
little more reminiscent of early-mid June instead of mid-May given
the fairly weakish mid level westerly winds (25 to 30 knots at
500mb) and the absence of a formidable short-wave trough, thus
keeping the surface frontal zone quasi-stationary for a prolonged
period of time -- which will mainly shift due to various
convectively-induced outflows. That being said, a stronger polar
front will move across western Kansas late Saturday Night/early
Sunday, putting an end to this stormy multi-day period. The ECMWF
shows a quite pattern developing with a 590 decameter 500mb ridge
forming over New Mexico, nosing into southwest Kansas early next
week. It remains to be seen how this will affect the next large
scale trough coming into the western CONUS early-mid next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 602 PM CDT Tue May 12 2020
LIFR ceilings can be expected overnight as a southeasterly wind
at 10knots or less continues across southwest and north central
Kansas. Areas of fog and drizzle will also be likely with
visibilities of 1/2mile or less being possible at times...mainly
from 06z and 14z Wednesday in the Dodge City and Garden City
areas. After 14z ceilings and visibilities will improve with MVFR
conditions developing by 18z Wednesday. VFR conditions are
expected between 18z and 21z Wednesday. Southeast winds at around
10 knots at 12z Wednesday will become more southerly by noon as
the wind speeds increase to around 15 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 44 77 55 81 / 10 20 10 0
GCK 43 85 50 81 / 10 10 10 0
EHA 47 89 52 84 / 0 0 0 0
LBL 45 89 52 84 / 10 10 10 0
HYS 44 73 55 79 / 20 20 20 0
P28 46 72 61 85 / 20 20 20 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Goodland KS
553 PM MDT Tue May 12 2020
.UPDATE...
Issued at 553 PM MDT Tue May 12 2020
Some locales are seeing reduction in visibility and have opted
for a Dense Fog Advisory issuance for the CWA thru 15z Wednesday.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 305 PM MDT Tue May 12 2020
Through Tonight: Strengthening SE-SSE upslope flow /low-level warm
advection will maintain the shallow cool/moist airmass in place
over the Tri-State area through tonight. No well-defined upper
level features can can be identified upstream this afternoon. In
the absence of focused upper forcing (i.e. DPVA) -- precipitation
will likely be confined to periods of drizzle. Fog will likely
re-develop after sunset, with dense fog possible late this
evening through tonight (similar to last night).
Wed-Wed night: The shallow cool/moist airmass will begin to mix-
out /recede eastward/ on Wed. Increasingly (albeit broad)
cyclonic flow aloft over the Western CONUS /WSW flow atop the
Rockies/ and a diurnally enhanced SFC-H85 baroclinic zone (on the
western periphery of the receding airmass) will aid in the
development of a lee cyclone in eastern Colorado during the day.
In the absence of discernible/focused upper forcing, significant
uncertainty persists with regard to (1) the timing (and extent to
which) the shallow/stable airmass will mix-out/recede and (2) the
precise evolution of the lee cyclone. Guidance suggests that the
aforementioned airmass will fully mix-out as far east as Hwy 283
(Hill City) by late afternoon. With weak synoptic forcing
(predominately confined to low-level convergence invof the
aforementioned sfc boundary) and a pronounced /renewed/ elevated
mixed layer advecting eastward from the Rockies into the Central
Plains -- convective development is far from certain. Simulated
reflectivity forecasts via the HRRR and NAM NEST show little or no
convective development in Northwest KS late Wed aft/eve. *If*
isolated updrafts (1) develop and (2) survive dry-air entrainment
ascending through the EML -- thermodynamic/kinematic profiles
appear supportive of supercells. Thus, a conditional potential for
severe weather will exist during the late afternoon and early
evening, mainly northeast of Goodland between 22-02Z.
.LONG TERM...(Thursday through Tuesday)
Issued at 158 PM MDT Tue May 12 2020
Unsettled weather continues into the long term period. On Thursday,
a shortwave passes across the northern Plains with a cold front
already through the region. A disturbance moves through the zonal
flow, generating chances for showers and storms in the afternoon
through overnight hours. Am anticipating storms to develop off the
Front Range and track eastward to the region through the evening. At
this point, do not see much of a severe threat as we will be post-
frontal, but a couple strong storms could occur.
Another wave is expected to eject over the Central Plains on Friday,
with a round of showers and storms moving into the region from
Colorado in the afternoon and crossing the area Friday night. With
better moisture filtering into the High Plains and better
instability, a few strong to severe storms could develop. Will
continue to monitor to pin down more details in the coming days.
Chances for showers and storms linger into Saturday as the shortwave
passes east of the region. Confidence in precipitation occurring
this day is low at this point due to disagreement among guidance
with the speed of the disturbance`s exit.
A large, upper closed low slowly approaches the west coast on
Sunday. Meanwhile, upper ridging builds out ahead and progresses
towards the High Plains. As a result, the region will see a change
in weather, with dry conditions and warmer temperatures.
A slight cooling trend is anticipated Thursday (70s/low 80s) through
Saturday (upper 60s/70s). Temperatures warm Sunday (70s), Monday
(80s), and Tuesday (low 90s). Low temperatures range in the 40s and
50s through the period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 530 PM MDT Tue May 12 2020
Through about 14z-16z Wednesday, both terminals will see mainly
IFR to LIFR ceilings ranging from OVC003 to OVC008. KMCK will see
brief MVFR ceilings around OVC010 thru about 02z before
transitioning lower. After about 14z-16z, VFR skies for KGLD,
while KMCK will see MVFR near BKN015 before going VFR by 18z.
Besides continued lowered ceilings, fog will be the other main wx
issue. Thru about 05z-06z Wed, both sites will see 5-6sm.
Afterwards 1sm or less, especially for KGLD. 14z-16z will have
2-3sm before going to VFR vsby.
Winds for KGLD, SSE around 15-30kts thru 16z, then SW around
10kts. Winds for KMCK, SE 10-20kts thru 16z, then diminishing to
10-15kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Dense Fog Advisory until 9 AM MDT /10 AM CDT/ Wednesday for
KSZ001>004-013>016-027>029-041-042.
CO...Dense Fog Advisory until 9 AM MDT Wednesday for COZ090>092.
NE...Dense Fog Advisory until 9 AM MDT /10 AM CDT/ Wednesday for
NEZ079>081.
&&
$$
UPDATE...JN
SHORT TERM...VINCENT
LONG TERM...JBH
AVIATION...JN
Area Forecast Discussion
National Weather Service Green Bay WI
1052 PM CDT Tue May 12 2020
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 247 PM CDT Tue May 12 2020
The latest RAP analysis and satellite/radar imagery show surface
high pressure centered over the northern Plains to the Ohio Valley.
A very dry airmass has resulted in clear skies and low humidity
levels between 15 to 25 percent across the region early this
afternoon. The northern edge of the return flow is not too far
away, and marked by the northern edge of mid-level clouds
stretching from Montana to Iowa. As high pressure moves across the
region tonight, forecast concerns continue to revolve around low
temps and the frost/freeze potential.
Tonight...The surface high will quickly move across the region to
the eastern Great Lakes by 12z Wednesday. Meanwhile, mid and high
clouds will gradually invade from the west after midnight. Ideal
radiational cooling conditions will therefore remain present
during the evening before clouds start arriving. This should
provide enough time for temps to fall into the upper 20s to middle
30s by late tonight. Used the best performing guidance for low
temps, then dropped the cold spots down by a degree or two. As a
result, will hoist a frost advisory from central to northeast WI.
Wednesday...The region will be positioned between high pressure
over the east coast and low pressure emerging into the Plains.
Deep layer south to southwest flow will continue to push in cloud
cover, so will see increasing clouds through the day. The morning
continues to look dry though, with more sunshine over far
northeast WI than further southwest. Humidity levels will likely
approach 25 pct again over far northern WI before rising in the
afternoon. As the moisture transport axis shifts east in the
afternoon, chances for showers will increase across north- central
WI. But the main push of precip will arrive on Wednesday night.
Because of gusty southeast winds, temps over far eastern WI will
likely cool off in the afternoon after thicker cloud cover
arrives. Highs should range from the mid 50s to near 60 at most
locations, locally cooler near Lake Michigan.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 247 PM CDT Tue May 12 2020
Mean flow is forecast to become more zonal or only slightly
amplified later this week which would allow more of a Pacific air
mass to spread into WI and bring warmer temperatures to the
region. There will be a good chance of showers/slight chance of
thunderstorms Wednesday night through Thursday as the warmer air
arrives, along with a mid-level shortwave trough. A stronger
shortwave trough is expected to arrive late Saturday into Sunday
morning and bring northeast WI another chance for showers/storms.
As a closed upper low hits the West Coast early next week, a
downstream upper ridge to develop over the central CONUS with
temperatures moving above normal.
A broad southwest flow aloft will pull gulf moisture northward
into WI ahead of a weak cold front Wednesday night. This moisture
transport, coupled with WAA, should bring a round of showers
across northeast WI. The atmosphere is only marginally unstable
with an elevated LI barely getting to zero over our southernmost
counties. Thus, only a slight chance of thunder mainly south of
Highway 10. Min temperatures to range from the lower 40s north/
near Lake MI, middle to upper 40s south. The chance for showers/
thunderstorms would continue into Thursday as the cold front moves
across WI. However, guidance indicates that heavier precipitation
would remain to our south (IA/southern WI/northern IL) in the
vicinity of a warm front. Depending on how far north this warm
front can get will determine if the northern edge of these heavier
rains can reach parts of central/east-central WI. For now, have
kept pops at a chance north/likely south and keep the heavy
rainfall to our south. Max temperatures Thursday to range from
around 60 degrees lakeside, lower 60s north, middle to upper 60s
south.
As this entire system (warm front/cold front/shortwave trough)
shifts east Thursday night, improving conditions will be observed
over the region. Look for a decrease in clouds, a light west-
northwest wind and min temperatures near normal. This would put
readings around 40 degrees far north, upper 40s across east-
central WI (slightly cooler near the lake). High pressure to move
across the Great Lakes region on Friday, bringing mostly sunny
skies and temperatures closer to mid-May values. This translates
to readings in the upper 50s near Lake MI, middle 60s to around 70
degrees inland.
Clouds are expected to slowly be on the increase Friday night as a
new system organizes over the central Plains. A shortwave trough
is progged to move into the northern/central Plains on Saturday
with a weak surface low to move into the Midwest. Increasing
south-southwest winds will begin to not only tap gulf moisture,
but also pull the old cold front north as a warm front into
central IA/northern IL by 00Z Sunday. Anticipate thickening cloud
cover with the leading edge of showers/possible thunderstorms
pushing into northeast WI, mainly during the afternoon. Max
temperatures Saturday to be in the middle to upper 50s near Lake
MI, middle to upper 60s inland.
Saturday night simply looks wet as the shortwave trough moves into
the Upper Midwest and a cold front enters WI after midnight.
Models vary with the strength of the corresponding surface low,
but with increasing mid-level forcing and lift from both the cold
front/right entrance region of the upper jet, prefer to ramp up
pops from the previous forecast. In fact, some of this rain may
become locally heavy at times. The showers/storms would continue
into Sunday as the cold front/shortwave trough push across WI. A
little too early yet to determine whether any of these storms
could become strong or severe. Max temperatures for Sunday to be
around 60 degrees lakeside, middle 60s to around 70 degrees
inland.
A ridge of high pressure to quickly advance into the western Great
Lakes region Sunday night, thus ending the precipitation and
allowing for skies to become partly cloudy. Monday looks like a
nice, Spring day with mostly sunny to partly cloudy skies and
temperatures warming above normal as an upper ridge builds
overhead. Max temperatures to reach the lower 60s near Lake MI,
lower to middle 70s inland.
The forecast for Monday night/Tuesday is more uncertain depending
on the strength of the upper ridge over the region. A stronger
ridge would keep any precipitation to our north and west along a
quasi-stationary front. A weaker ridge could allow this front to
sag south and bring chance pops to at least northern WI. Have
followed the consensus solution which only bring a minimal pop to
northern WI on Tuesday. We do expect warm and more humid
conditions to return by Tuesday with max temperatures in the
middle 60s lakeside, middle 70s to around 80 degrees inland.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1052 PM CDT Tue May 12 2020
Continue good flying conditions with VFR skies and cloud cover
through Wednesday afternoon. Winds are expected to remain fairly
light and variable through the night.
Cloud cover will increase and thicken during the day Wednesday
with high clouds moving in Wednesday morning and mid clouds
developing/moving in Wednesday afternoon. It is possible that a
few showers could move into the central WI TAF sites late
Wednesday afternoon, but most of the models are keeping the
precipitation out of the area until Wednesday evening. As the rain
moves into central WI, ceilings will likely drop into the MVFR
range. The pressure gradient will also tighten ahead of the next
system, allowing gusty southeast winds to develop through the day
Wednesday, with some gusts reaching to around 25 mph. As the
atmosphere becomes more stable Wednesday evening, some LLWS will
likely develop under an inversion.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT Wednesday for WIZ020-022-030-031-
035>040-045-048>050-073-074.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kallas
AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Hanford CA
132 PM PDT Tue May 12 2020
.SYNOPSIS...
Storm system continues to impact Central California today by
bringing cooler temperatures into the San Joaquin Valley and
strong winds through Kern County. Below average temperatures
across the forecast area along with periods of gusty winds in Kern
County will persist for the next few days. Brief warmup later in
the week, followed by another storm system that will impact the
forecast area starting next Sunday.
&&
.DISCUSSION...
Scattered showers passed through the San Joaquin Valley this
morning as a trough of low pressure slowly approaches the West
Coast. Fort Ord profiler reveals a marine layer close to 3,000
feet as of of this writing, which reflects the cool, onshore flow
we are receiving today. Afternoon highs today will generally be in
the mid to upper 70s across the forecast area, which is several
degrees below average. The main impact this storm system will
bring to the forecast area this afternoon though early tomorrow
morning is strong winds through Kern County. HRRR analysis and
short range guidance shows a significant pressure gradient forming
across the Tehachapi Mountains through this afternoon, capable of
producing wind gusts near 60 mph. Therefore, a High Wind Warning
has been issued through 5 AM Wednesday through and just below the
Tehachapi Mountain passes, as well as the Mojave Desert in Kern
County. Another burst of shortwave energy looks to pass through
the main trough tomorrow afternoon, which will likely lead to
another round of gusty winds in the Tehachapi Mountains/passes
and Mojave Desert. Otherwise, expect another day of cooler than
average temperatures across the forecast area.
Shortwave ridging starts to build late on Thursday, which will
mark the beginning of a short-lived warming trend. Near normal
afternoon high temperatures can be expected Friday in the low to mid
80s. Upper 80s across the San Joaquin Valley can be expected
Saturday, which will be a few degrees above normal for mid May.
Model confidence is increasing that another trough of low pressure
will near the California Coast by Sunday. This will re-introduce
chances of precip (likely light) across the forecast area, cooler
temps, and strong winds in the usual wind-prone areas. More
specific details of upcoming impacts from this next storm will be
clarified in later forecast packages.
&&
.AVIATION...
Occasional wind gusts around 50 knots are possible over the
ridges and through and below the Kern County mountain passes
through 12Z Wednesday. VFR conditions will otherwise prevail
across the Central CA interior for the next 24 hours.
&&
.AIR QUALITY ISSUES...
None.
&&
.CERTAINTY...
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
an/or to provide feedback.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 5 AM PDT Wednesday for CAZ196-198-199.
&&
$$
public...Bollenbacher
aviation....Bollenbacher
weather.gov/hanford
Area Forecast Discussion
National Weather Service Wichita KS
1002 PM CDT Tue May 12 2020
...Evening Update for Overnight Thunderstorm Potential...
.MESOSCALE DISCUSSION...
Issued at 959 PM CDT Tue May 12 2020
Quick update on the possible convective evolution overnight into
Wednesday morning...
Low-level water vapor imagery and 00z observed upper air soundings
show two areas of moisture advection this evening. One is rooted
around 700-600mb and is advecting in from western KS. The other is
rooted closer to 850mb, and is advecting north out of OK. Meanwhile,
there may be a subtle mid-level s/w over eastern CO.
Observed soundings reveal some mid-level warming is ongoing at this
time, which will likely limit where any elevated convection
overnight can be rooted. RAP forecast soundings appear to be
handling the incoming mid-level moisture from the west fairly well.
Based on this, it still appears that there will be enough moistening
above the inversion, combined with some lift from the CO s/w, to
produce scattered thunderstorms after Midnight tonight. Unless the
low-level moistening is being underdone by the models, storms should
be rooted near/above 700mb, which may only allow 250-500 j/kg MUCAPE
to be realized, with somewhat weaker shear. If the mid-level temps
end up cooler, or if the low-level moistening is more pronounced,
then up to 1000 j/kg MUCAPE could be realized, along with slightly
better shear.
Bottom line, confidence is increasing in elevated storms developing
overnight into Wednesday morning, but the severe threat looks very
conditional. If storms remain rooted at/above 700mb, severe weather
would be unlikely. If storms can be rooted a bit lower, the
potential would exist for hail up to quarter size.
Martin
&&
.SHORT TERM...(This evening through Friday night)
Issued at 303 PM CDT Tue May 12 2020
Model sounding show periods of drizzle possible through the night
with deep low-level saturation persisting. Current satellite total
precipitable water analysis shows that deeper Gulf of Mexico
moisture has been streaming northward across Texas reaching the
confines of southern Oklahoma. This moisture will continue to spread
northward tonight and interact with a north to south aligned
elevated frontal boundary. This could spark off elevated
showers/storms for late tonight into Wednesday morning across
central and south central Kansas. Expected wind shear/instability
aloft supports a few strong or possible marginal severe storms. This
activity will slide eastward during the morning hours tomorrow.
Meanwhile, models still suggest a warm front will migrate northward
into the area with increasing low level moisture during the day
tomorrow. A fairly strong cap aloft combined with residual low
clouds could be a substantial prohibiter for surface based
thunderstorm development in the wake of elevated morning convection.
Therefore, believe next round of storms will be tied to convergence
areas along the dry-line (positioned well west and southwest of
central/south central KS) during the mid-late afternoon hours. Some
of this activity could try and spread into south central Kansas
later Wednesday evening, but it would be fighting against the
capping temperatures aloft. Thinking that elevated storms should re-
develop north of the warm front Wednesday night, however that
moisture transport looks to target northeast Kansas thus sparing
most of our area. Still cannot rule out a few storms from
attempting to develop in the strong moisture transport axis over
our area.
A weak frontal boundary will sag southward during the day on
Thursday and should be the focus for afternoon/evening storms. Shear
aloft is on the weaker side but instability will be plenty high
enough for severe multi-storms to materialize. The forecast becomes
a little more uncertain for Thursday night into Friday. Although
models do show a fairly pronounced mid-level front draped over
the area with a long duration of warm moist advection aloft. This
shows signs of generating numerous showers/storms across the
region. Flooding could become a bigger issue across the area by
Thursday night into Friday due to widespread recent rains of
1-2.25 inches soaking the ground soils and causing rises on local
rivers.
.LONG TERM...(Saturday through Tuesday)
Issued at 303 PM CDT Tue May 12 2020
Thunderstorm chances will continue for Saturday across the region
with chances tapering off by late Saturday night, as a more
substantial frontal boundary pushes east of the region.
High confidence of dry weather to prevail for Sunday-Tuesday as long
range models show well pronounced upper ridging building over the
central plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 642 PM CDT Tue May 12 2020
*Low CIGs and DZ/BR to linger into at least Wednesday morning
*SHRA/TSRA possible overnight, and again later Wednesday
Low CIGs continue to persist across much of Kansas this evening,
and will likely linger well into Wednesday. It appears there will
be enough low level lift for periods of DZ overnight into
Wednesday morning. Additionally, SHRA and TSRA may develop after
05z, posing a risk of reduced VIS and possibly some hail.
Confidence in TSRA development is lower for now, and I opted to
remove any TSRA/VCTS mention in the TAFs. This will be closely
monitored, though, with amendments if confidence increases. CIGs
may rise some on Wednesday, with a few breaks in the clouds
possible, especially southern Kansas. This factors in for
where/if TSRA can redevelop Wednesday afternoon/evening. Stay
tuned.
EXTENDED OUTLOOK: TSRA will remain a concern through the upcoming
weekend.
Martin
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 49 72 64 82 / 30 30 20 30
Hutchinson 47 69 61 81 / 30 30 20 10
Newton 48 69 62 80 / 30 30 30 30
ElDorado 48 73 63 81 / 30 40 30 40
Winfield-KWLD 50 75 64 82 / 30 40 20 30
Russell 44 72 55 79 / 20 20 20 10
Great Bend 45 72 57 81 / 20 20 20 0
Salina 48 68 60 80 / 30 30 30 20
McPherson 47 67 60 80 / 30 30 30 20
Coffeyville 51 75 65 79 / 30 40 10 30
Chanute 49 74 65 78 / 20 50 20 50
Iola 48 73 64 78 / 20 50 30 60
Parsons-KPPF 50 75 65 79 / 30 40 20 40
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
MESOSCALE...RM
SHORT TERM...CDJ
LONG TERM...CDJ
AVIATION...RM
Area Forecast Discussion
National Weather Service North Platte NE
628 PM CDT Tue May 12 2020
.SHORT TERM...(This evening through Wednesday night)
Issued at 311 PM CDT Tue May 12 2020
A warm front accompanied by dry air is currently across Colorado
this afternoon. The front will move east into wrn Nebraska tonight
triggering scattered showers and isolated thunderstorms, mainly
across nrn Nebraska. The dry air aloft should cause an area of fog
to form affecting areas along and west of highway 83. Southeast
winds and increasing moisture beneath the dry air would support an
advection type fog. The RAP model shows this fog affecting the
highlands with lower visibility than the valleys.
The dry air and clearing should move through wrn Nebraska Wednesday
morning and progress into ncntl Nebraska during the afternoon. A
second area of showers and thunderstorms is expected to form off the
Colorado Front Range and Laramie Range Wednesday afternoon. The
showers and thunderstorms should move through wrn and ncntl Nebraska
Wednesday night.
The temperature forecast leans on the short term model blend which
works well with warm air advection patterns, it incorporates
deterministic model temperatures and tends to limit the fall in
temperatures at night. Temperatures Wednesday will be moderated by
the progress of the clearing line. Continued warm air advection,
increasing cloudiness and a chance of showers and thunderstorms
Wednesday night would suggest the short term model blend would be
the preferred forecast tool vs the cooler guidance blend.
.LONG TERM...(Thursday through Tuesday)
Issued at 311 PM CDT Tue May 12 2020
Shower and thunderstorm chances continue Thursday, Friday and
Saturday. This rain chance is associated with the slow eastward
migration of an upper low off the coast of Oregon this afternoon.
The upper low is expected to track through MT and SD placing wrn and
ncntl Nebraska in the southern or warm advection side of the system.
A weak area of Pacific high pressure will build into wrn and ncntl
Nebraska ahead of the upper low and this should set up a stationary
front for focus.
Once this upper low moves into the Great Lakes late Saturday, a new
upper low, currently across the Aleutians, should drop south and
move into the Great Basin forming a long wave trof. The trof should
flush warm air out the Desert Southwest and into the Central high
Plains (CHP). WPC has outlooked the CHP for much above normal
temperatures Monday and Tuesday. The GFS ensemble and other models
keep the sfc low pressure near the WY-SD border and this would place
the warmest air across wrn Nebraska and the Panhandle. Highs in the
80s are in place both days across all of wrn and ncntl Nebraska.
Future forecasts could feature highs near 90 in some areas as
suggested by the GFS guidance. H700mb temperatures will be rising to
between 10C and 15C which supports highs of 90 or warmer if mixing
heights can reach 700mb.
The forecast is dry Sunday through Tuesday. The very warm air aloft
predicted across the region should "cap" thunderstorm chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 627 PM CDT Tue May 12 2020
Ceilings will continue to fall overnight at both the KLBF and KVTN
terminals, becoming IFR at the KLBF terminal and MVFR at the KVTN
terminal overnight. Ceilings will become VFR late morning
Wednesday with clearing skies expected into the afternoon hours.
Fog will be possible across southwestern Nebraska overnight,
impacting the KLBF terminal from 10z through 17z. Visibilities may
fall off to 1SM overnight.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Buttler
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
1003 PM EDT Tue May 12 2020
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
As of this writing time, regional radar is showing light rain
moving across middle TN and starting to reach the central plateau,
however, surface observations indicate that this is not reaching
the ground. There is alot of dry air remaining below 700 mb
leading to this virga. As the surface high slowly shifts off of
the FL coast tonight and lee cyclogenesis takes shape east of the
Rockies, a warm front that currently stretches from AR across
central MS and AL will slowly lift into the southern TN valley.
Strengthening WAA and isentropic lift ahead of the front will
continue to moisten the 700-500 mb layer late tonight, and
soundings show some saturation nearing the surface after 09Z, so
updated PoPs to reflect a gradual expansion of slight chance to
chance from W to E between now and 09Z. The latest RAP and NAM,
along with HREF ensembles suggest a strip of light showers in the
08-15Z timeframe from the central plateau through the central
valley into NE TN and SW VA, so confidence is quite high that
there will be at least scattered showers. QPF will be very light
with generally 0.02 or less. The rest of the forecast remains on
track.
RG
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR will generally prevail through the TAF period, but a warm
front lifting into the southern Appalachians will begin
increasing mid level moisture late tonight. As a result, cigs
will lower through the night with a BKN to OVC layer between 3 and
5 thousand feet developing after 08Z at TYS and TRI, while higher
cigs dominate at CHA. Isolated showers are also possible late
tonight into late Wednesday morning, but coverage is low
confidence, so included VCSH and Prob30 groups for a few hours at
TYS and TRI which could result in very brief periods of MVFR cigs
and vis. Conditions will rapidly improve by late afternoon.
RG
&&
.PREV DISCUSSION...
/ISSUED 255 PM EDT Tue May 12 2020/
SHORT TERM (This Afternoon through Wednesday)...
The period of below normal temperatures continues throughout the
short-term forecast. Temperatures as of 2 PM are in the upper 50s to
mid 60s for most locations. Seeing more cloud cover today compared
to the last couple of days with increased moisture in the mid-
levels. Mid to upper level flow is generally northwesterly with a
closed upper level low to the north across New England. Seeing a few
weak shortwave troughs in this northwesterly flow rotate through the
area. At the surface, a warm front extends across north Texas to the
east into the Lower Mississippi River Valley. The low-levels across
the southern Appalachians remain dry with surface dewpoints
currently in the 30s. PW values are higher than yesterday and range
from around 0.5-0.6 inches across northeast Tennessee/southwest
Virginia to near an inch for southwestern portions of the forecast
area. These values near an inch are much closer to normal for mid-
May. Current radar imagery indicates a few light returns showing up
across northern Alabama associated with lift to the north of the
warm front. There are some observations of the precipitation reaching
the ground in northwest Alabama. Overall, expect the low-levels
remain too dry for rain this afternoon and evening. The area of
isentropic lift to the north of the front will continue to increase
overnight. Look for best chances of any precipitation around 5 AM -
11 AM Wednesday morning when this area of lift moves through. Warm
air advection will return to the area later this evening into the
overnight hours as the low-level high shifts to the east. Overnight
lows will be warmer than the last few nights in the low 40s to low
50s for most locations. Rain chances will decrease late tomorrow
morning into the afternoon from south to north. Overall, any
rainfall will be light with amounts under a tenth of an inch. Highs
tomorrow will range from low 60s in northeast Tennessee and
southwest Virgina where clouds and light precip. will linger longer
to upper 60s to low 70s for locations generally south of I-40.
MA
LONG TERM (Wednesday night through Tuesday)...
Some scattered showers may still linger Wednesday night as the front
continues to move northward towards the Ohio River Valley. However,
forecast models still indicate that the best lift will remain to our
west closer to the shortwave.
Ridge begins to build in strength quickly on Thursday and
temperatures will also increase in response. Expect high
temperatures to reach into the upper 70`s and even the 80`s. With
the building ridge will come more southerly winds which should help
keep dew point values somewhat elevated, and these combined with the
strong daytime heating means we should see some isolated/scattered
showers and thunderstorms through the end of the week and into the
weekend. Best precipitation chances will be over the higher terrain
that may help spark showers and thunderstorms, especially along the
Cumberland Plateau into SW Virginia along the outer edge of the
surface high.
Towards the end of the weekend a cold front will move down from the
Ohio Valley, but there is not much of a push with this front and the
higher moisture associated with it remains further north closer to
the low. So we will see an increase in precipitation chances, but
coverage and QPF amounts are still expected to be somewhat limited.
After the front moves through a ridge quickly builds in behind it
and temperatures remaining near or above normal.
ABM
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 53 76 58 81 62 / 20 20 0 10 0
Knoxville McGhee Tyson Airport, TN 51 70 54 81 61 / 30 30 0 10 0
Oak Ridge, TN 50 69 53 81 60 / 30 40 0 10 0
Tri Cities Airport, TN 43 63 51 78 56 / 30 30 10 20 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
833 PM PDT Tue May 12 2020
.SYNOPSIS...Isolated to scattered rain showers will remain
possible at times through early Thursday, with the best chance of
precipitation over the North Bay. Temperatures across the interior
are forecast to remain below normal through Thursday, while
coastal temperatures will be near seasonal averages. Drier
conditions and slightly warmer temperatures are expected from
Thursday through at least midday Saturday before cooler, unsettled
conditions return late in the upcoming weekend.
&&
.DISCUSSION...As of 8:30 PM PDT Tuesday...Isolated shower
activity has decreased since early evening and all shower activity
is expected to end by sunset. Dry conditions are forecast
overnight and through about midday Wednesday.
The longwave upper trough responsible for our wet weather over the
past few days remains nearly stationary offshore with its axis
centered along 130W. Two more shortwaves moving through the
longwave trough are expected to trigger additional shower
activity, the first between late Wednesday morning and Wednesday
afternoon, and the second from late Wednesday night through about
midday Thursday. Precipitation in both cases is forecast to be
light and primarily confined to the North Bay, although the 00Z
NAM and latest HRRR indicate isolated light showers from San
Francisco southward, especially on Wednesday afternoon and
evening. Additional rainfall through Thursday is forecast to be a
quarter inch or less in the North Bay, with no measurable rain or
just a few hundredths elsewhere.
Inland temperatures will remain below seasonal averages through
Thursday, while coastal temps hold near normal.
Dry conditions will return to all areas by Friday, as will warmer
temperatures, as a shortwave ridge briefly develops over
California. Dry conditions will then likely persist into Saturday
morning before the next late-season system spreads rain across our
area from Saturday afternoon through Sunday. Models agree that
the system due in next weekend will be stronger, and track
farther south, compared to the current system. Therefore,
precipitation is likely to be more widespread, especially across
the southern part of our area. Also, thunderstorms could develop
by late Sunday night or Monday as a cold upper low tracks across
northern California.
&&
.AVIATION...as of 5:59 PM PDT Tuesday...for 00z TAFs. VFR. A few
isolated showers will diminish by sunset. VFR to MVFR ceilings and
a local patch or two of valley fog is possible late tonight and
Wednesday morning. Light to moderate showers arrive over the North
Bay Wednesday morning with MVFR to IFR developing, elsewhere mainly
MVFR to VFR.
Vicinity of KSFO...VFR to MVFR tonight, VFR Wednesday. West wind
to 15 knots this evening diminishing to light and variable early
Wednesday morning. West wind increasing to 10 to 15 knots in the
afternoon and evening.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR to MVFR tonight, VFR Wednesday. West
to northwest winds diminishing and becoming light and variable
tonight. West winds redeveloping Wednesday.
&&
.MARINE...as of 5:25 PM PDT Tuesday...Generally light to locally
moderate south to soutwest winds will persist through tonight
before winds over the southern waters begin to transition back out
of the northwest. Southerly winds will briefly return across the
southern waters tomorrow afternoon as another weak boundary moves
through. West to northwest winds will then return later this week.
Mixed seas will continue with a moderate northwest swell and a
longer period southerly swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...None.
$$
PUBLIC FORECAST: Dykema
AVIATION: Canepa
MARINE: AS
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Area Forecast Discussion
National Weather Service Pocatello ID
135 PM MDT Tue May 12 2020
.SHORT TERM...tonight through Thursday night. A low pressure
system off the Pacific Northwest coast continues to send waves of
moisture through central and east Idaho. We are seeing showers and
a few thunderstorms drift through the region. This activity will
continue through the night, although the odds for thunder will
decrease with nighttime cooling. A lake wind advisory is in effect
for this evening for the American Falls Reservoir where winds of
around 20mph were observed at Aberdeen and Sterling.
We may see a few more showers on Wednesday and Thursday as the low
pressure system slowly advances inland. The increase in clouds/rain
will produce lower temperatures as well. Winds are expected to
remain breezy on Wednesday but not so much on Thursday. Lake wind
conditions may be realized again on Wednesday.
13
.LONG TERM...Fri through next Tue night. The upper level low
responsible for all the showers and thunderstorms previous to this
day actually starts lifting out from its nearly stationary positions
on the OR-CA coast and moves through southern Idaho during the day
Fri. This still means dry northwesterly flow develops Fri night and
continues during the day Sat, for the driest day of the seven days
in the complete forecast. Another closed low slides into the OR-CA
coast, and starts up a repeat of stormy weather. However, it does
not linger as long out in the Pacific. By Wed/Wed night, just
outside of this forecast period, this upper level low is moving
through Idaho. Both lows are creating enough unstable conditions
that daytime heating should mean thunderstorm activity every
afternoon and evening except Sat. At this time, there are no
significant impulses bringing in a strong front, so do not expect
thunderstorms to be severe. Messick
&&
.AVIATION...Extensive cloud cover has been slow to leave, and most
model guidance has eliminated TSRA in the Snake River plain and
eastern Magic Valley. Satellite imagery paints a different story,
with a large hole in the cloud cover moving eastward and into
eastern Idaho at this time. So have kept TS activity to just VCTS
for KIDA, KPIH, and KDIJ. KSUN and KBYI are in much more stable air
on most products, so have lowered expectations at those two
airdromes to VCSH. A second band of clouds, with scattered SHRA, is
expected after 13/06Z in eastern Idaho. The SHRA surrounds KSUN in
the mountains, so have left that and KBYI as VCSH. However, the HRRR
indicates KPIH and KIDA to take a more direct hit, so have a period
of -SHRA for both airports. For KDIJ, this second wave should
actually bring marginal VFR along with the showers. Wind-wise, every
location is looking for elevated west to southwest wind for much of
the night, with only KSUN slowing and shifting to its normal
northwest flow. KPIH and KBYI likely to stay at least southerly.
Messick
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 10 PM MDT this evening for IDZ054.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
444 PM MST Tue May 12 2020
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
A cooling trend will bring temperatures back to around normal
readings beginning today, lasting through Friday while dry
conditions prevail. Increased afternoon breeziness will be common
for much of the week as several weather systems move well north
of the area. The fire weather threat will remain elevated as well.
Increasing high pressure into the weekend will lead to warmer
temperatures and highs once again reaching near 100 degrees.
&&
.DISCUSSION...
Dry westerly flow across the region has now pretty much cleared
skies entirely across our CWA this afternoon and dropped sfc
dewpoints into the 20`s at many lower desert locations. These dry
conditions (Rh`s in the high single-number to mid-teen range) and
locally gusty winds are resulting in elevated fire danger levels as
well. Winds have been strongest at the usually-favored locations
across SW Imperial County, with gusts over 30 mph already being
reported. Latest NAM-3km and HRRR high-res models continue to
forecast the winds to continue to increase through the remainder of
the afternoon/evening hours. with gusts to 50 mph possible. Thus, a
Wind Advisory remains in effect through 5 am Wed for SW Imperial
County. Highs today are still expected to top out in the low-mid
90`s, noticeably cooler than they have been the last few days.
Further cooling is still forecast for Wednesday as 500mb heights
lower a bit more, with lower desert highs falling into the upper-80
to low-90 range, along with some afternoon breeziness once again.
These near to slightly below normal temperatures look to last
through Thursday before weak ridging begins to move in from the west
starting Friday.
Another deep trough is shown dropping out of the northern Pacific
on Friday before slowly moving southeastward into the Pacific
Northwest this weekend. This trough will amplify the ridge
already in place across the Southwestern U.S. leading to further
warming across our region. Latest model trends have slightly
higher heights and warmer temperatures building over our region
which should push lower desert highs close to 100 degrees for this
weekend. Into next week, much higher model spread is seen as the
closed low potentially moves into California and the Great Basin
next Monday into Tuesday. This should lead to a bit of a dip in
temperatures for early next week and potentially even more if the
trough continues to sag southward into our region sometime during
the middle of next week. Even if the trough were to move through
the Desert Southwest at some point next week, it is highly
unlikely it would bring much in the way of any rain chances to the
region. The main impact from next week`s trof will likely be an
increase in winds and fire danger levels.
&&
.AVIATION...Updated at 2345Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Gusty westerly winds will continue through this evening and for a
few hours after sunset. The strongest gusts this afternoon may
reach the 20-25 kt range although most will remain below 20 kts.
The return of the overnight easterly winds are less certain, and
may not develop until the 9-12Z timeframe. As such, there may be
periods of light speeds, mostly AOB 8 kts, and variable directions
beginning very late tonight and lasting through tomorrow morning
until the westerly winds resume around 19-20Z.
Southeast California/Southwest Arizona including KIPL and KBLH:
Strong, westerly and southwesterly winds will remain in place
through this evening and much of the night. At KIPL, wind gusts
nearing 30 kts may be common until early tomorrow morning.
Occasionally stronger "mountain rotor" winds may reach the
terminal area. At KBLH, wind gusts of 22-26 kts are likely until
6Z. For tomorrow, gusts will return by the early afternoon but at
speeds weaker than the last two days.
&&
.FIRE WEATHER...
Friday through Tuesday: Warmer temperatures are expected for the
upcoming weekend, with lower desert highs likely returning to near
100 degrees by Sunday and Monday along with widespread dry
conditions. Afternoon humidity levels will remain low in the teens
across all districts while overnight recovery improve to a 30-40%
range in eastern districts and closer to 50-60% in western
districts. Stronger winds and cooler temperatures are forecast for
Tuesday, as a late-season Pacific low pressure system approaches the
region. Gust speeds 20-30 mph will be possible, even locally 35-40
mph across southeast California, enhancing the fire danger
particularly in areas with abundant cured fine fuels.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT Wednesday for CAZ562.
&&
$$
DISCUSSION...Percha/Kuhlman
AVIATION...AD
FIRE WEATHER...Percha/Benedict/MO
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Wednesday)
Issued at 409 PM CDT Tue May 12 2020
Plenty of challenges remain with the forecast in the next couple of
days. For today, radar has continued to show very light returns with
drizzle occurring in east central KS this morning into the early
afternoon due to weak isentropic lift. Forecast soundings
(NAM/RAP/HRRR) in Emporia keep the low levels saturated through the
evening and overnight hours, and areas further north toward Topeka
and Manhattan show the low levels gradually becoming saturated late
this evening and remaining so overnight. As such, have added drizzle
to the forecast increasing north with time this evening and lasting
through the overnight hours across much of the CWA. With WAA
increasing, temperatures should remain steady or even rise slightly
through the night with lows expected in the mid to upper 40s.
By early tomorrow morning, WAA increases further with a
strengthening LLJ of 30-40 kts. This is when we`ll be watching for
the first round of storms, some of which could potentially become
strong. The exact timing and placement of storms remains uncertain
as some models have placed these more in north central KS while
other runs have them in east central KS. Regardless, a brief window
of stronger storms at least looks like a possibility with elevated
instability increasing after 12Z. The NAM seems to keep the better
CAPE in north central KS (up to 1000 J/kg), while the RAP carries
this instability into east central KS during the mid to late morning
as well. 0-6 km bulk shear of 25-35 kts keeps the strong storm
potential more in question during this time frame, but with the LLJ
and the instability, can`t entirely rule out some large hail with a
few storms.
The next chance for thunderstorms comes tomorrow evening, but this
also comes with uncertainties. Low pressure deepens in eastern CO
with most models showing storms initiating ahead of a dryline in
western KS during the late afternoon/early evening. This also
coincides with a weak mid-level shortwave moving over the state
during the 18-00Z time frame, and the LLJ is expected to strengthen
further to 40-50 kts late in the evening. Questions remain on when
and if storms will get going with a strong cap in place, but these
factors could result in enough lift to overcome that cap. The other
question is how much instability -- the NAM has MUCAPE of up to 2500-
3000 J/kg in east central KS, while the GFS has considerably less
based on forecast soundings. Based on the elevated nature of these
storms, large hail and some damaging winds are the main hazards.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 409 PM CDT Tue May 12 2020
By Thursday morning, a frontal boundary looks to extend from
southwestern to north central KS, which moves across the state
during the day and will be the focal point for the next chance of
storms. The best chance looks to be in east central KS along and
southeast of the boundary by the late afternoon. CAPE of 1500-2500
J/kg could once again bring the threat of hail and damaging wind,
although it is worth mentioning that the NAM keeps this area more
capped while the GFS erodes the cap during the afternoon.
The frontal boundary remains in the area through Friday and Saturday
with on and off chances of showers and storms during this period,
although am not expecting more rounds of severe weather at this
time. The main concern by this point is the potential for minor
flooding and locally heavy rainfall, especially over areas that may
see repeated rounds of storms.
Sunday afternoon into Tuesday, a drying pattern is expected to
return as an amplified ridge moves into the area. Temperatures are
generally expected to reach the 70s and 80s for the afternoon, but
could reach the mid 80s by Tuesday with the strengthening ridge.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 633 PM CDT Tue May 12 2020
Not much change from previous forecast. Flying conditions are
expected to deteriorate through the overnight period with CIGS
dropping to IFR and drizzle possible after 06Z. A further
reduction to LIFR CIGS is looking more likely after 09Z at all
terminals. Thunderstorm development still looks possible early
tomorrow morning, so have continued mention of VCTS by 15Z. Some
improvement is expected during the afternoon, but IFR CIGS should
remain in place much of the period. Will monitor trends for the
possibility of another round of storms developing late in the
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Picha
LONG TERM...Picha
AVIATION...Teefey
Area Forecast Discussion
National Weather Service Tulsa OK
927 PM CDT Tue May 12 2020
.DISCUSSION...
Warm front, currently located just south of the Red River this evening,
will begin to lift north overnight. Areas of light rain/drizzle will
likely persist north of boundary with a slight chance for an isolated
thunderstorm or two as low level jet begins to develop. Whatever
precipitation does occur should remain relatively light both tonight
and into the day Wednesday with only minor QPF amounts.
Storms that develop in southwest Oklahoma Wednesday afternoon may begin
to weaken significantly as activity moves into eastern Oklahoma
Wednesday evening/overnight as CIN increases/boundary layer begins
to stabilize. Taking a quick look at latest NAM, HRRR and WRF-NSSL
models continue to support this scenario.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...12