Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/21/20
Area Forecast Discussion
National Weather Service Grand Forks ND
942 PM CDT Mon Apr 20 2020
.UPDATE...
Issued at 942 PM CDT Mon Apr 20 2020
Clear sky has developed as high pressure builds into the region.
Winds will continue to diminish and should be light and variable
at some point after midnight.
Watching the incoming guidance for Tuesday weather impacts. Not
much change to the previous thoughts. Large temperature gradient
across the region with a couple shortwaves quickly moving across
the baroclinic zone should lead to to periods of snow/rain. At
this point predictability is still low with details as the main
forcing mechanism is Fgen and the upper waves in the northwest
flow are not strong. Every solution is slightly different and will
stick with the previous messaging.
UPDATE Issued at 618 PM CDT Mon Apr 20 2020
Was able to allow the Red Flag Warning to expire at 6pm. Will be
able to allow the wind advisory to expire at 7pm. One last area of
scattered showers now across the central Red River Valley expected
to continue to propagate south/southeast but diminish in the next
hour or two. Still expect high pressure to build into the region
this evening with sky clearing and winds diminishing. No impacts
expected through tonight.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 308 PM CDT Mon Apr 20 2020
Winds and shower activity will continue to be the main challenges
for the period.
Scattered showers continue across the forecast area, mainly from
peak heating as the main shortwave has move southeastward into MN.
Several of the model solutions from this morning show a lot of
momentum transfer across most of our area this evening. So far the
gusts have mostly been staying below 40 mph except for Valley City
and Cooperstown at times, which is in the wind advisory. Some of
the model soundings show the boundary layer mixing all the way to
700mb, which would bring 50 to 60 mph gusts. The RAP even shows
the possibility of 65 or 70 in some places. Cold air advection is
helping with some mixing, and there could be enough clear spots in
the shower activity this afternoon to mix a bit more. Not sure we
will get to 700mb, but at least 925 to 850mb where winds are
around 35 kts. Will continue to keep the wind advisory going in
our southwestern counties where there has been the most consistent
high gusts, and will keep an eye on the other counties through
this evening. Conditions will be much more quiet after sunset with
weak surface high pressure building in and showers dissipating
with the loss of heating. Temps should get pretty cold tonight
with 20s and even some upper teens in NW MN where dew points are
pretty low.
Northwest flow aloft continues into tomorrow, and there will be a
jet streak digging down that will put northwestern MN into the
right entrance region of the feature. Frontogenesis is strong,
especially at 850mb, as a warm front lifts into the CWA with 60s
in southeastern ND and upper 30s/low 40s. Synoptic lift is not
quite as strong, and although some models are indicating some
banding potential, there is also the question of temperatures.
Even with some cooling thanks to precip evaporating into dry air,
think that any snow showers will mostly melt as they fall during
the day on Tuesday. Maybe a dusting of snow as temperatures drop
at night. A few of the CAMs try and break out a narrow band of
higher QPF values and even some mixed precip is not out of the
question. Given all the uncertainty will just continue to keep an
eye on things as conditions develop tomorrow.
.LONG TERM...(Wednesday through Monday)
Issued at 308 PM CDT Mon Apr 20 2020
The chance for impactful weather is low within the long term period.
Still expecting a warming trend to temperatures near normal, ie lows
in the 30s and highs in the 50s to 60s. While the pattern is looking
to become more active towards mid to late this week, significant
precipitation is not forecast within the long term period.
Wednesday starts cool with temperatures in the 20s and 30s with a
small chance of very light precipitation, possibly a wintry mix for
Minnesota locations. Warmer temperatures aloft should be in place by
the start of Wednesday behind Tuesday`s system as the upper pattern
remains northwesterly to zonal flow. This should allow highs to
reach into the 50s and 60s, again cooler into northwest Minnesota.
Upper pattern begins to shift Thursday and beyond with troughing
favored over the Upper Midwest mid to late this week. This will
bring period chances for light precipitation, especially on Thursday
as a system is progged to develop out of the central or northern
Plains into the Upper Midwest. Temperatures should remain warm
enough that all rain is favored as the precip type. Still too early
to comment on total QPF from this system as an uncertain track
dictates this detail. With general troughing starting to build near
the area, extensive cloudiness may moderate diurnal temperature
swings with highs in the 50s and lows in the 30s generally expected.
After this weekend, upper ridging or at least a breakdown of the
troughing is forecast which would indicate warmer temperatures
possible.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 618 PM CDT Mon Apr 20 2020
Scattered VFR cigs will dissipate quickly this evening leaving
clear sky. Winds will also diminish and will be light and variable
at some point tonight. Clear sky and light winds will continue
until later Tuesday morning. Anticipate southerly winds along with
VFR cigs at some point Tuesday afternoon. There is the low chance
for a band of precipitation somewhere within the region, but at
this time not sure where that will exist.
&&
.HYDROLOGY...
Issued at 942 PM CDT Mon Apr 20 2020
Pembina and Drayton remain at major flood stage. Pembina is expected
to remain in major flood stage until the weekend. Drayton is
expected to fall into moderate flood stage early Wednesday.
Satellite continued to indicate a flood area generally east of I-29
from Manvel northward to Pembina ND. Road closures and overland
flooding remain in and near this flooded area. Oslo continues at
moderate flood stage and was the only forecast point at moderate
flood stage. Fargo and East Grand Forks were at minor flood stage.
East Grand Forks is expected to remain at minor flood stage until
the weekend. Fargo is expected to fall below flood stage until early
Thursday. Hallock, Abercrombie, Kindred, Harwood, Mapleton, and the
West Fargo Diversion were at a high water stage.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.
&&
$$
UPDATE...TG
SHORT TERM...JR
LONG TERM...CJ
AVIATION...TG
HYDROLOGY...JH
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
826 PM CDT Mon Apr 20 2020
...Fire Weather Update...
.UPDATE...
Issued at 825 PM CDT Mon Apr 20 2020
The bottom line:
The Red Flag Warning was allowed to expire on time for our entire
Nebraska coverage area (CWA) at 8 PM, as the last of the gusty
winds from the afternoon hours are steadily diminishing and
relative humidity (RH) values will continue a steady rise from
currently 20s/30s to well into the 40s to around 50 percent over
the next 1-2 hours. For more fire weather info (including a recap
of today and a peek at "near-critical" potential tomorrow, please
refer to the separate FIRE WEATHER section below...
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 410 PM CDT Mon Apr 20 2020
Upper air analysis reveals NW flow across the central Plains due
to troughing over E third of CONUS and ridging over W third.
Visible sat has blossomed w/ diurnally driven cld cover over the
past couple of hrs, aided by deep cyclonic flow on the backside of
potent vort max S of Hudson Bay and deep mixing. The deep mixing
allowed temps to quickly rise late AM along with momentum
xfer of gusts 35-40mph. But w/ some areas now experiencing broken
cld cover, temps have leveled off or even dropped a few deg.
Fire weather issues in the very near term are discussed below.
After sunset this eve, winds and lingering CU/Stratocu will
quickly diminish as sfc ridge axis moves in from the NW. Mostly
clr skies and relatively dry airmass should allow for cool low
temps in the mid 30s to around 40. If winds really fall off,
usual cold spots and low lying areas could fall to near freezing.
Tuesday looks to be a much more pleasant day compared to today as
temps will be warmer and winds much much lighter. The upper level
flow will flatten some as the NE trough shifts E. After
coordination w/ neighbors, decided to incr Tue highs above
guidance, closer to extended RAP values. NBM and MOS blends have
been consistently too cool as of late, and don`t see why Tue would
be any different given copious amounts of sunshine expected. This
gives highs in the mid 70s. As mentioned above, winds will be
much lighter out of the south around 5-15mph, with maybe some
gusts closer to 20mph for the aftn. All in all, a very nice day!
May see some incr clds late in the day over the far SW, ahead of
our next disturbance. There`s a slight chc some shwrs could sneak
into Rooks and Philips Co by sunset, but overall, best chcs remain
further S/SW until Tue night.
.LONG TERM...(Tuesday night through Monday)
Issued at 410 PM CDT Mon Apr 20 2020
A bit of a "messy" pattern in the extended w/ multiple pcpn chcs,
but overall not very wet, and a mix of seasonably warm and cool
temps.
The upper pattern will continue the transition towards a
flatter/more zonal look thru midweek. A progressive shortwave
trough will shift E thru the Plains Tue night into Wed, but it
looks like the brunt of this upper energy will slide by to our S.
Wed night into Thu looks quiet, before another disturbance arrives
in the zonal/NW flow later Thu in Fri, w/ perhaps another wave
sometime around Sat. Then it appears upper ridging will build Sun
into early next week.
POPs have generally been reduced for the Tue night into Wed time
frame as models suggest the core of upper energy remains largely
across KS/OK. NAM remains the most aggressive w/ pcpn
coverage/intensity along its N shield, but tend to favor
ensemble/EC which keeps the N shield more muted. Have 20-30 POPs
mainly along and S of the state line. Chcs appear a little better
Wed aftn w/ some daytime heating along and ahead of a weak cold
front. Modest CAPE values suggest some thunder potential, but
shear values are weak. Highs look to range from upper 60s to mid
70s, coolest across KS zones where cld cover will be thickest.
Thu looks to be another mild day ahead of next cold front and weak
disturbance. This front may eventually spark off some shwrs or
tstms Thu aftn/eve into the overnight, but it doesn`t look like
anything too organized. Best chcs will be over the E half of CWA.
Temps will cool off behind this system, with mainly 60s expected
for Fri and Sat. Current 20-30 POPs for Fri may be overdone, as
latest EC suggests mainly dry day. A shortwave in the NW flow
could spark off some mainly diurnally driven shwrs on Sat, but
again, nothing too heavy or organized. So again, extended is
littered with several pcpn chances, but would not expect much QPF
out of these given their origin and the upper pattern, and some
places may miss these altogether.
Ensembles are in good agreement for a warming trend Sun into early
next week, with 80s a good possibility for at least portions of
the CWA.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 654 PM CDT Mon Apr 20 2020
General overview:
High confidence in VFR ceiling/visibility and rain-free weather
through the period, with only limited mid-level "fair weather"
stratocumulus mainly right away this evening, and then again
perhaps Tuesday afternoon. That leaves winds as the primary issue,
as gusty northwesterly speeds right away this evening will quickly
die down overnight, before somewhat-breezy southerly speeds kick
in for Tuesday afternoon. Read on for more wind-related details if
interested...
Wind details:
The last of pronounced afternoon northwesterly gustiness will
steadily subside this evening, but not before providing at least 1
more hour of gust potential to roughly 25KT. Already by 02Z,
sustained speeds should be under 10KT, with a light/variable-
direction regime then taking hold through much of the late-
night/early morning hours as surface high pressure translates
through. By mid-morning Tuesday southerly breezes will start to
become established again, and most of the afternoon will feature a
steady south-southwesterly wind frequently gusting 15-20KT.
&&
.FIRE WEATHER...
Issued at 825 PM CDT Mon Apr 20 2020
Follow-up on Monday`s Warning:
There are very FEW "fire weather afternoons" during the
spring/fall where conditions end up being "better"/less-severe
than anticipated, but this was actually one of those rare cases
where most of the Warned area struggled to consistently drop to 20
-percent-or-lower RH. Despite this "verification technicality",
still feel the Warning was largely warranted from an impact-based
standpoint given that RH values were "close enough", and
especially given that northwest winds were every bit as strong (if
not a bit stronger) than anticipated, as most areas notched peak
gusts of 35-40+ MPH. We also had (unofficial) word of at least one
grass fire that got out of hand for a time in our far western
CWA.
Looking ahead:
Will defer to overnight shift to make the "final call" whether
it`s worthy of introduction to our Hazardous Weather Outlook, but
technically we are now forecasting parts of our Nebraska CWA to
realize "near-critical" fire weather Tuesday afternoon (meaning
overlap of RH 25 percent-or-less and wind gusts 20 MPH-or-
higher). However, unlike today, south winds tomorrow should not be
nearly as strong, precluding critical conditions and the need for
a formal Warning.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Pfannkuch
SHORT TERM...Thies
LONG TERM...Thies
AVIATION...Pfannkuch
FIRE WEATHER...Pfannkuch
Area Forecast Discussion
National Weather Service Wichita KS
1032 PM CDT Mon Apr 20 2020
.SHORT TERM...(This evening through Thursday)
Issued at 331 PM CDT Mon Apr 20 2020
A weak cold front continues to push south across the forecast area
this afternoon, with remnants from last nights convection over
eastern KS dropping southeast into SW MO. Latest RAP does show
some SBCAPE around 100 j/kg over extreme SE KS this afternoon, but
the RAP also shows most of the moisture transport focusing the
better moisture into SW MO. But as the front pushes SE, still
could see a brief window for an isolated storm to develop over
extreme SE KS for late this afternoon, as convergence increases
and lapse rates steepen. Will keep a low pop in for a few hours
late this afternoon, before any convective chances shift further
E-Se into OK and SW MO.
For the rest of the evening and overnight hours, expect mostly clear
skies, as a weak area of high pressure rapidly drops southeast over
the area. Expect seasonal temperatures for overnight lows.
Weak ridging will remain in control for most of the daylight hours
on Tue, as the ridge moves slowly east-southeast into the Ozarks.
Attention then turns back to the west, as the next shortwave in the
NW to zonal flow pulls out of the southern Rockies and into the
plains for Tue afternoon. Latest models suggest that this shortwave
will come into the plains in two pieces, with the initial impulse
increasing lift and moisture transport for Tue afternoon for SW KS.
Think scattered showers and some thunder will slowly shift east into
south central KS by Tue evening, or possibly as late as overnight
Tue. Not alot of instability as this initial impulse comes out, so
think scattered showers and possibly an isolated storm or two will
be the main concern.
Second and stronger impulse looks to move out into the plains for
early Wed, with a low pressure area developing over the OK
panhandle. Some uncertainty on the track of this low, with the GFS
taking it straight east across northern OK, while the ECMWF takes
the low further south along the Red River. Both models seem to
agree that the main mid level impulse and mid level frontogenesis
associated with it, will move along the KS/OK border. This
secondary shortwave has better moisture transport and increasing
instability for early Wed morning. Think the rainfall amounts Wed
morning will become more widespread than late Tue night. Bulk shear
and elevated instability suggests possibly some strong to marginally
severe storms for early Wed morning for areas south of highway 54,
and certainly closer to the KS/OK border. Expect the heaviest
rainfall amounts, around an inch, to be across southern KS and areas
east of the KS Turnpike.
Expect the showers and embedded storms to continue off and on across
southern and SE KS for a good portion of the daytime hours on Wed,
before gradually ending from west to east by Wed evening. Am a
little concerned with the GFS showing the shortwave deepening over
SW MO for Wed afternoon, which may lead to heavier rainfall amounts
of 1.5 to 2 inches over extreme SE KS by Wed evening. This could
lead to some localized flooding over SE KS if it materializes.
Expect another lull in shower/storm chances for late Wed thru early
Thu, as weak mid level ridging moves across the area. Good downslope
flow will lead to max temps on Thu, climbing well above normal into
the upper 70s, and possibly into the low 80s for portions of central
KS.
Ketcham
.LONG TERM...(Thursday night through Monday)
Issued at 331 PM CDT Mon Apr 20 2020
The dry conditions will be short lived, as another shortwave in the
NW flow will drop SE across the forecast area for late Thu night as
a cold front drops south. Could see scattered showers and
thunderstorms for Thu evening into Thu night, with post frontal
showers lasting into early Fri for much of southeast KS as well.
Some uncertainty on how the weekend will play out, as NW flow will
lead to a rapid succession of weak shortwaves dropping southeast.
The next small chance looks to drop southeast for Sat.
Ketcham
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1030 PM CDT Mon Apr 20 2020
VFR conditions will prevail across central and southern Kansas
with light and variable winds switching to the southeast tomorrow.
Showers and storms look to develop over northern Oklahoma and
southwest Kansas which could push into central/south central
Kansas by Tuesday evening.
&&
.FIRE WEATHER...
Issued at 331 PM CDT Mon Apr 20 2020
Widespread rainfall rainfall expected for Tuesday and
Wednesday will lead to grassland fire values remaining low.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 49 75 52 64 / 0 0 50 70
Hutchinson 45 75 51 63 / 0 0 50 60
Newton 46 73 51 62 / 0 0 40 60
ElDorado 46 74 51 64 / 0 0 50 80
Winfield-KWLD 47 75 53 65 / 0 10 60 80
Russell 43 76 48 68 / 0 10 40 40
Great Bend 43 75 48 66 / 0 10 50 40
Salina 42 76 50 65 / 0 0 40 50
McPherson 43 74 50 62 / 0 0 40 60
Coffeyville 46 75 52 64 / 10 0 50 90
Chanute 45 73 51 62 / 10 0 40 80
Iola 44 73 50 62 / 10 0 30 70
Parsons-KPPF 47 74 52 63 / 10 0 40 80
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Ketcham
LONG TERM...Ketcham
AVIATION...CDJ
FIRE WEATHER...Ketcham
Area Forecast Discussion
National Weather Service Lubbock TX
632 PM CDT Mon Apr 20 2020
.AVIATION...
Showers across the northern half of the Texas Panhandle should
stay north of the terminals. VFR conditions expected through much
of the night with stratus expected to develop again late tonight
toward dawn Tuesday. Models now focusing more on KLBB and KPVW for
ceilings near high end IFR and low end MVFR with KCDS more
questionable regarding extent of low cloud. Improvement expected
early to mid afternoon Tuesday.
&&
.PREV DISCUSSION... /issued 245 PM CDT Mon Apr 20 2020/
SHORT TERM...
Afternoon RAP 500 mb analysis and water vapor imagery indicates an
open wave pivoting into the Sierra Nevada Mountain range, along with
a substantially weakened mid-level ridge oriented across the Rocky
and Cascade Mountain region. At the surface, a weak, stalled front
is draped across central New Mexico into central Texas. A surface
low will begin to develop this evening across east-central New
Mexico, with a pseudo-warm front that will drift north across the
CWA overnight. As this happens, boundary-layer moisture will
increase and a shallow stratus deck is forecast to develop during
the mid-morning hours across the region in addition to localized
patchy fog. Moisture return will continue throughout the morning and
into the early afternoon hours, with a nose of strong theta-e
advection orienting itself across the northeastern Rolling Plains
Tuesday afternoon.
Advected Layer Precipitable Water (ALPW) imagery indicates a modest
EML across the Desert Southwest, and this EML will continue to
advect east into the forecast area during the overnight hours.
Strong ML theta-e advection, identified on ALPW imagery and modified
1200 UTC RAOBs from Flagstaff and Albuquerque, will result in the
development of stout convective inhibition across the forecast area
tomorrow afternoon. Beneath the EML, a moist boundary-layer will
exist, characterized by a 60 deg F isodrosotherm and mean mixing
ratios near 11-13 g/kg draped across the northeastern Rolling
Plains. Backed surface winds will aid in localized surface
convergence; however, surface-based parcels will likely fail to
reach their LFCs due to strong CINH. The erosion of CINH should be
rather slow during the early part of the day until the stratus deck
mixes out. However, vertical thermodynamic profiles are supportive
for the development of an isolated, high-based supercell or two
across the central areas of the extreme southern Texas Panhandle and
northeastern Rolling Plains Tuesday afternoon. This remains quite
conditional despite the presence of an EML characterized by MUCAPE
near 1,000-1,500 J/kg and favorable deep-layer shear.
Should convective initiation occur, the orientation of the deep-
layer shear profile (i.e. relatively straight, long hodographs) will
favor strong precipitation ventilation in updrafts given anvil-level
storm-relative winds in excess of 50 knots. LP supercells will be
the primary storm mode with broad, mid-level mesocyclones supporting
an attendant risk for hail production of 1-2" in diameter. Storms
that do develop will have a residence time of several hours as they
move along the southern Panhandle due to the increase in the low-
level jet coincident with the arrival of the mid-level jet streak
and associated wave. Chances for storms will begin to diminish after
dark and upon passage of the cold front.
Sincavage
LONG TERM...
Overall a quiet pattern is expected through the weekend. The axis
of the upper trough will be across our western FA border by
Wednesday morning and will push to our east by the afternoon. Some
light showers and thunderstorms will be possible as the trough
moves across the FA. A weak cold front will follow behind the
upper low with highs getting into the low 70s to low 80s.
Northwesterly flow will dominate going into late week. An embedded
shortwave is progged to push across the central US Thursday
evening/Friday morning bringing a slightly stronger cold front as
the airmass source region is central Canada. This results in highs
only in the 60s and 70s on Saturday. Winds are expected to
quickly return to the south by Sunday.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 256 PM CDT Mon Apr 20 2020
Our Monday afternoon has been a breezy one, but still plenty warm
despite the gusty northwest winds across the region. Temperatures
are in the upper 60s to lower 70s with winds gusting 30-40 mph at
most locations. Humidity fell into the 17-28 percent range as
expected, with additional decreases likely in the next few hours,
and the resulting very high to extreme fire danger will persist
through approximately 7 PM today. One interesting feature at the
moment is the southwesterly extension of a short wave trough as
the trough axis is moving across the forecast area this afternoon.
Ahead of the trough axis have seen an increase in shallow cumulus
cloud cover at the top of the mixed layer near 10k feet AGL. There
are a few weak returns showing up on radar, but with the high
cloud bases and RH around 20 percent it is very unlikely that
precip will reach the surface. Behind the trough, subsidence is
evident in WV imagery over SD and now moving into far northern NE.
This has helped to increase wind gusts a bit to 40 kts or
stronger. Northeast NE may experience a few of these stronger
gusts in the late afternoon hours as well, but should see a
general decrease in the intensity as we approach sunset.
Surface high pressure builds over the region tonight with winds
becoming light by morning. This will offer an efficient
radiational cooling night once the winds die down, and have
adjusted temperatures a bit cooler than most guidance especially
in northeast NE. Tuesday will feature a return of light southerly
flow and warm advection. Model guidance has been persistently much
too cool and moist with surface T/Td predictions in similar days
this spring so have gone several degrees warmer and a good amount
drier than almost all guidance...leaning close to a RAP solution.
This will result in another day with RH potentially at or below
20 percent, but winds will be light enough that there is no
extreme fire danger expected. Rather, it will probably be a "Top
10 day" with widespread upper 60s to mid 70s, sunshine, and light
winds.
Expect a bit of low-level moisture return on Wednesday in advance
of a weak cold front. This could be sufficient to spark showers
and a few thunderstorms along the advancing front in the
afternoon. At this time, instability appears minimal and surface
convergence along the front is not clearly strong enough to
initiate convection so strong storms are unlikely. A better chance
of rain arrives late Thursday into early Friday with a strong
storm system and attendant cold front. Once again, instability is
weak and while thunderstorms are possible it appears unlikely to
pose any organized severe threat at this time. A few areas may
pick up a half inch of rain or so. Will have some cold advection
behind this system with Fri/Sat/Sun highs in the 60s. For the most
part, morning lows should be around 40, but IF high pressure and
clear skies should time themselves to arrive around sunrise on any
given morning could see temperatures approach freezing.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 716 PM CDT Mon Apr 20 2020
No significant aviation impacts are expected through 00Z Tuesday.
Conditions should be VFR, with light and variable winds tonight
becoming light southerly winds between 15 and 20Z Tuesday.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Barjenbruch
AVIATION...Albright
Area Forecast Discussion
National Weather Service Nashville TN
725 PM CDT Mon Apr 20 2020
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
A weak cold front is situated to our northwest early this evening
and will swing across Middle Tennessee later tonight. In spite of
relative dry air in place, the front should be able to gather up
enough moisture to squeeze out a few light showers during fropa.
The latest HRRR does show scattered light echoes from late this
evening until early Tuesday morning, but all precipitation should
be gone by 12Z. Then we`ll get back to mostly sunny skies tomorrow
and pleasant temperatures. Hourly grids are in good shape for
now. No forecast changes are planned this shift.
&&
.AVIATION...
00Z TAF DISCUSSION.
Conditions will stay VFR for the next 24 hours. A quick moving
clipper system will move through the terminals overnight, but 00z
OHX sounding shows ample dry air in the low levels. A couple light
showers or sprinkles could impact the terminals, but cigs should
stay VFR. Winds behind the system will shift to the NW and remain
around 10 kts. Winds will become gusty by mid morning with gusts
to around 20 kts for the remainder of the day.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......08
AVIATION........Reagan
Area Forecast Discussion
National Weather Service Pueblo CO
344 PM MDT Mon Apr 20 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 344 PM MDT Mon Apr 20 2020
...More Active weather expected for Tuesday...
Orphaned upper trof over the western U.S. will get picked up by
Pacific jet energy and will translate eastward under the ridge and
across CO on Tuesday. Ahead of this system this evening...high
based showers and thunderstorms will be possible, particularly
across the mountains and adjacent plains and southern border areas
through this evening. CAPE is rather limited as low level moisture
remains meager...so main threat with thunderstorms this afternoon
and evening will be erratic gusty winds to around 40 mph or so.
Thunderstorms should range from isolated to scattered in coverage at
best.
Activity winds down this evening, but with the approaching system
will see shower chances increase again across the southwest
mountains after midnight, spreading northeastward with time across
southern portions of the southeast plains towards dawn. By morning
should see fairly widespread rain and embedded thunderstorms
spreading northward across the plains as moisture advection and
overrunning sets up across the plains north of the front across
NM/TX. Question will be how much instability there will be for
strong to severe afternoon thunderstorms and how far north these
ingredients will spread. Majority of the high res models keep
stronger activity to the south, with 12z experimental HRRR the most
optimistic model in bringing potential for marginal severe storms
into Baca and Las Animas counties in the afternoon. 18z run seems
to be shifting focus southward. To some extent moisture return
tonight and amount of heating on Tuesday will be the primary driver
of severe potential tomorrow. If all goes well, up to 1000 J/kg of
CAPE could be lurking along the southern border with deep layer
shears running around 40 kts or greater. This would lead to the
potential for one or two strong to severe storms with hail the
primary threat. However morning convection could also serve to
stabilize things too much which would limit activity across
southeast CO and place focus farther south. Either way, it appears
there will be a good chance for some wetting rains across much of
southern Colorado, and will carry high pops. Have leaned the
forecast towards a more southward focus for severe potential, but
this could change with later model runs.
Higher elevations will also see a good chance of snow late tonight
through Tuesday, with snow levels wavering between 9-10Kft. Snow
accumulations of 2-5 inches will be possible across the higher
elevations above 10000 feet. The higher peaks and passes along the
Continental Divide will likely see slushy to snowpacked conditions
at times under the heavier snow showers. Will have to watch the burn
scars in the southeast mountains, particularly Spring and perhaps
Junkins burn scar for heavy rainfall on the lower elevations of the
burn scar. But for now think snow levels may be locally driven down
lower and or small hail/graupel with any stronger embedded
convective elements should help offset flash flood concerns. -KT
.LONG TERM...(Tuesday night through Monday)
Issued at 344 PM MDT Mon Apr 20 2020
Not many adjustments required from previous longer term
meteorological reasoning as additional upper disturbances
impact the CWA into late this week.
Initially, scattered to numerous showers as well as isolated to
scattered thunderstorms(some on the stronger to potentially
severe side over the far southeastern Colorado Plains and also
capable of producing locally heavy rainfall) ongoing late Tuesday
afternoon/evening as an upper disturbance(per PV analysis)
continues to impact primarily southern locations.
Also, have depicted additional 12 hour snow amounts up to 3 inches
over favored higher terrain locations from 6 PM MDT Tuesday to 6
AM MDT Wednesday.
A brief lull in activity is expected over the CWA from Wednesday
afternoon into Wednesday night in advance of next system producing
generally isolated to scattered pops(including thunderstorms and
higher terrain snow) from Thursday into at least Friday night.
Then, drier and warmer conditions are still expected to develop
over southern Colorado(especially from later in the weekend into
early next week) as upper ridging builds into southern Colorado.
Minimal fire weather concerns are expected continue over the
majority of the CWA into the weekend, with increasing fire
potential developing by early next week.
In addition, it still appears that the highest potential for more
widespread gusty winds over the CWA during the longer term should
be realized over primarily eastern locations from Tuesday night
into Wednesday and then again from Thursday evening into Friday
night.
Finally, coolest temperatures during the longer should still be
noted Friday, with warmest temperatures expected Sunday and
especially Monday(with maximum temperatures on Monday expected to
climb into the 80s over many eastern locations).
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 344 PM MDT Mon Apr 20 2020
VFR conditions expected at the TAF sites with high based showers and
isolated thunderstorms this evening. Main threat will be gusty
erratic winds up to 30 kts near high based showers this evening
along with brief VFR CIGS. CIGS will lower overnight but
predominantly remain VFR at all three TAF sites (KCOS, KPUB and
KALS). A wave of showers will lift northward bringing the chance
for some -SHRA at KALS early Tues morning, spreading northward into
KPUB and KCOS by mid day. Some local MVFR cigs will be possible
under the heavier showers and isolated embedded thunderstorms during
the afternoon. Mountain areas will see mtn obscurations spread in
late tonight along the Continental Divide spreading eastward into
the southeast mountains on Tuesday. Expect IFR to LIFR conditions
over the mountains above 10000 feet with periods of SHSN. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Area Forecast Discussion
National Weather Service Las Vegas NV
845 PM PDT Mon Apr 20 2020
.SYNOPSIS...An area of low pressure will slowly move across the
area and bring another round of showers and isolated thunderstorms
to parts of the region. Impacts are expected to be low but a few
lightning strikes and gusty outflow winds are possible where storms
develop, mostly off higher terrain. Dry and much warmer weather is
on the way for the latter half of the week and lasting into the
weekend. Expect plenty of sunshine to go along with the warmer
weather and occasional breezy winds.
&&
.UPDATE...The area of showers and thunderstorms that brought record
rainfall to Las Vegas this afternoon continues to shift northeast
this evening and are currently moving out of Clark County and into
northern Mohave County. With loss of afternoon heating these showers
and storms have been gradually weakening with just a couple of
lightning strikes over the past hour. Rainfall rates have also
decreased significantly with just a few hundredths reported. There
have been a few pop up isolated showers across southern Inyo and
eastern San Bernardino Counties this evening, but overall these will
remain weak and produce additional light rain amounts. Forecast in
good shape and no updates planned.
&&
.AVIATION...For McCarran...Outside of a light shower overnight,
conditions are not expected to be impactful overnight. Light diurnal
winds and mid-level clouds are expected. Winds will likely turn
northward Tuesday morning with a frontal passage. North winds may
approach 10-12 knots at times. Shower activity is not expected in
the valley, but cannot rule out outflow winds from showers that
develop over the terrain.
For the rest of southern Nevada, northwest Arizona and southeast
California...Shower activity will be widely scattered overnight
across the Mojave Desert and southern Great Basin. Most sites should
remain dry; however, light showers cannot be ruled out in the Owens
or Las Vegas valleys. With showers, temporary lower ceilings are
possible otherwise ceilings will stay between 8-12 kft. Winds are
expected to be light and favor diurnal trends up until a frontal
passage tomorrow (Tuesday) which will redirect winds northerly.
&&
PREV DISCUSSION
231 PM PDT Mon Apr 20 2020
.SHORT TERM...through Tuesday.
Latest HREF and HRRR trends continue to show showers and isolated
thunderstorms developing after this afternoon out west off the
higher terrain of Inyo County and around 00Z farther east as the
weak low moves over the region. While this low will produce a
similar low end PoP/Thunder chance for this evening to what we`ve
seen over the last several days, this activity will be largely
driven by instability and lack dynamic support. Thus feel fairly
confident that initiation will be largely tied to higher terrain
areas such as the Springs, Sheep Range, and possibly Black
Mountain. That being said, RAP instability shows some impressive
CAPE values and with the cooling 500 mb temps and increasing
surface moisture this evening, can`t argue with the trend upward.
So included thunder over a larger area than previous forecasts,
now encompassing much of Clark County. DCAPE values look meager
compared to previous days but can`t rule out some gusty outflow
winds up to 30 mph with thunderstorms either.
The low is progged to center itself over southern Nevada by early
tomorrow morning and shift east moving into the afternoon so PoP
potential lingers through the overnight period but looks looks less
likely after 12Z Tuesday and should be more confined to
.LONG TERM...Wednesday through the Weekend.
A much more benign weather pattern is in store through the rest of
the period. The biggest news for the long term period is the
prospect for the first 90+ degree day for the LV Valley and 100+
day for Death Valley which looks like it will be Thursday before
a brief cool down Friday and Saturday and return to 90+ highs by
Sunday according to the latest NBM. The first broad, significant
amplitude ridge looks to build over the eastern Pacific as our
current low pushes east and will shift to the west coast by the
late week. This should serve to finally push the overall flow well
to the north and keep any new shortwaves across the northern US or
Canada. Looking all the way through 240hrs, there is good
agreement in the 12Z deterministic long range models and diving
into ensemble analysis, this only question seems to be how deep
will it get and thus how much warmer will get in the 8-10 day time
frame. NBM seems to be fully on board with such agreement so no
changes were made at this time to the long term.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...TB3
AVIATION...Kryston
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