Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/30/21
Area Forecast Discussion
National Weather Service Denver/Boulder CO
841 PM MDT Sat May 29 2021
.UPDATE...
Issued at 828 PM MDT Sat May 29 2021
Scattered showers and thunderstorms will continue this evening
across the county warning area, especially across Douglas and
Elbert counties. The severe threat has diminished but could still
see some brief heavy rain and small hail with the stronger storms
across the Palmer Divide where the best instability still resides.
Elsewhere, mainly scattered light rain showers over the mountains
and locations further north towards the Wyoming border. Northern
Colorado will remain under weak synoptic scale ascent for the rest
of tonight with continued showers. Have lowered rain chances over
the I-25 corridor this evening with more stability in place.
Upslope flow will deepen a bit overnight with some increase in low
level moisture. Could see some light rain showers/drizzle as well
especially later tonight. Best chances of widespread showers will
delay until Sunday afternoon as upslope continues to deepen and
strengthen.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 324 PM MDT Sat May 29 2021
Only a couple of storms have managed to develop this afternoon,
with a cluster near the Douglas/Elbert county line along with a
single cell in far northern Weld county. The rest of the urban
corridor has actually seen some decent clearing outside the few
convective cells, though temperatures are generally still in the
low to mid 60s. Day cloud phase also shows an area of low stratus
over our far northeast, stretching from Limon and into
Julesburg/Holyoke. Underneath this cloud deck, temperatures have
remained near or below 60. Over the higher terrain, generally
light rain showers have been noted, with only a few of these
producing any lightning activity. One recent cell has produced
some heavy rain over the Cameron Peak burn area, while most of the
higher terrain has been quiet.
A recent ACARS sounding from KDEN and a special sounding released
by CSU illustrate why convection has struggled over the plains
thus far... with a robust capping layer evident near 750-700mb. It
will be difficult to get widespread surface-based convection to
develop over the urban corridor this afternoon unless strong
surface heating can occur in the next couple of hours. The HRRR
and a few other CAMs try to warm us up to near 70F in the next few
hours, with another round of stronger convection moving off the
southern Foothills, but it`s worth noting that high-resolution
guidance has struggled with the overall convective evolution so
far. This makes the forecast for the next several hours pretty
uncertain. Given the clear skies over the southwestern metro into
portions of the southern Foothills, this would probably be the
most likely area to see stronger storms initiating again sometime
in the next few hours, with continued scattered showers and weak
storms for most of other higher terrain.
We should see showers persist through most of the overnight hours
as weak upslope flow deepens a bit across the area. Models do
show a skinny CAPE profile overnight so even a few rumbles of
thunder will be possible as we head towards daybreak. With the
light/moist upslope flow there could be some patchy fog across the
area near daybreak, which has been added into the grids. Tomorrow
morning should see precipitation blossom yet again with continued
upslope flow. Confidence is low on how this precip sets up. It`s
difficult to say what exactly the models are keying into, as
there`s not a whole lot of synoptic scale lift around.
Nonetheless, the good agreement in ensemble guidance is hard to
ignore and we expect widespread light to moderate rainfall for
much of the day. It wouldn`t be surprising to see daytime rainfall
amounts near an inch in some spots. Showers will continue into
the evening hours and overnight. Details on the rest of the rain
below.
.LONG TERM...(Sunday night through Saturday)
Issued at 324 PM MDT Sat May 29 2021
The models continue to gradually slow the departure of the trough
and the steady rain. Most solutions keep at least a little rain on
the plains into Monday. While the forcing for the heavier rain is
probably past, there`s no drying yet and weak upslope winds
continue. This means we`ll stay cool as well. Monday may be a
transition day with a little drying for areas west of the Front
Range, but for the east side it`s just less rain. We`ll slow the
whole thing down another 6 hours and drop temperatures Monday by a
couple of degrees.
After that, the trend is toward a little sharper transition from
trough to ridge. This means there`s some drying but still enough
moisture for scattered mainly diurnally/terrain driven storms on
Tuesday, then quicker and stronger warming Wednesday into
Thursday. These days look relatively dry, but with the surface
moist and some southerly low level flow on the plains there will
probably still be low grade convection. It may well stay warm and
dry into next weekend, but there are some differences with a weak
short wave that pushes a weak boundary southward at least into
Wyoming. If it comes further south it could set up some increase
in storms and a little cooling for Friday and Saturday. For now
our model blend looks appropriate, which is still warm with a
little below average thunderstorm activity for early June.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 828 PM MDT Sat May 29 2021
MVFR ceilings have developed over DEN/APA in the past hour with
continued shallow northeast flow. Isolated showers/TS also
developing near APA and will include until 05z. Expect mainly
isolated/scattered coverage of showers overnight with expected
lowering ceilings later tonight. Best chance of widespread
showers will be Sunday afternoon through Monday.
&&
.HYDROLOGY...
Issued at 324 PM MDT Sat May 29 2021
Flooding threat will continue through the rest of today. A few
heavier showers and storms have started to re-develop this
afternoon, which could pose a brief flash flooding risk over the
burn areas. A more widespread rainfall event is expected early
tomorrow morning through much of the day. Precipitation rates will
likely be light to moderate, leading to a low flash flooding
risk. Rainfall totals through tomorrow evening will be close to an
inch, which will fall over a 6 to 12 hour period.
Rain will likely continue over the east slopes of the Front Range
Sunday night and Monday but the intensity should be less. On the
west side of the Front Range there may still be some thunderstorms
on Monday afternoon, but again the intensity is expected to be
less. The threat of flooding should be low during this time,
although if there are issues on larger streams from Sunday`s rains
the additional rain would prolong the problems. Lighter rain is
expected on the plains and flooding is not expected.
From Tuesday on through the week a low level of thunderstorm
activity is expected over the mountains, and storms should be
moving faster. The threat of flooding will be low.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Entrekin
SHORT TERM...Hiris
LONG TERM...Gimmestad
AVIATION...Entrekin
HYDROLOGY...Gimmestad/Hiris
Area Forecast Discussion
National Weather Service Dodge City KS
1054 PM CDT Sat May 29 2021
...Updated Aviation...
.SHORT TERM...(This evening through Sunday)
Issued at 1259 PM CDT Sat May 29 2021
Upper air analysis and water vapor satellite imagery show weak
upper level ridging is in place over the central and southern
plains early Saturday afternoon, with a shortwave trough upstream
over far southern CA. As these features move east during the day,
a surface low in eastern NM/southeastern CO will be maintained
bringing southeast winds to southwest KS. This moist upslope flow
has allowed skies to stay mostly cloudy, but visible satellite
shows clouds are eroding as diurnal heating and boundary layer
mixing are chipping away. Given at least some sunshine, afternoon
highs will reach into the low 70s for most areas, with the far
western zones seeing mid to upper 70s possible.
IR/visible satellite are already showing agitated cumulus building
over the southern Rockies in CO, and this is an early sign that
thunderstorms will initiate over the higher terrain in the next
few hours. NAM/GFS and various CAMs are in general agreement this
activity will spread into western KS later this evening or
tonight, and given a favorable CAPE/shear parameter space, would
pose a severe wind/hail threat mainly to areas west of US-83. With
time and eastward extent, a stabilizing boundary layer will
preclude severe potential. During the overnight hours, CAMs are in
decent agreement that a strengthening low level jet will cause a
rapid increase in convective coverage over southwest KS and
adjacent southeast CO and OK panhandle. These storms will likely
be elevated in nature, and therefore pose little to no severe
risk, but heavy rain/flash flooding will be a concern as storm
motion is expected to be slow.
Showers and thunderstorms may be ongoing Sunday morning as the
overnight convective complex moves slowly south or southeast. In
its wake, overcast skies will exist over southwest KS, supported
by surface winds acquiring a more upslope component. Isolated to
scattered showers are possible Sunday as subtle disturbances eject
into the central plains ahead of the parent shortwave which will
have moved into the Desert Southwest by Sunday afternoon. Given
the overcast skies and lack of any appreciable warm advection,
afternoon highs on Sunday will only reach into the low to mid 60s.
.LONG TERM...(Sunday night through Saturday)
Issued at 245 PM CDT Sat May 29 2021
Upper level flow will be mostly zonal over the central plains at
the beginning of the long term period, with a weak shortwave
trough over the Desert Southwest. At the surface, a weak low
pressure system over the southern plains will move slowly
southeast Monday morning through the afternoon, dragging a weak
cold front through southwest KS. Weak northeast winds behind the
front and overcast skies will keep Monday afternoon highs in the
low to mid 60s. Scattered showers and possibly a thunderstorm are
also possible Monday as subtle upper level disturbances move into
the central plains, but given the cold surface temperatures,
severe weather in not anticipated.
On Tuesday, the upper level pattern will begin to become blocked,
as a classic Rex Block becomes established over the western CONUS
with a building ridge over the Pacific Northwest, and a weak cut-
off low retrograding somewhat over the northern periphery of
Baja, Mexico. Scattered showers may linger into the day Tuesday,
but the incipient upper level pattern will lead to a warm, dry
pattern through the end of the period. Overcast skies will begin
to dissipate during the day Tuesday, and afternoon highs will
reach into the mid to upper 60s. Wednesday and beyond, little
change to the weather is expected as the Rex Block continues to
dominate. Afternoon highs will increase from the upper 70s on
Wednesday into the upper 80s by Saturday with southwest to
southeast winds and partly cloudy skies.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1054 PM CDT Sat May 29 2021
High confidence of widespread poor flying conditions through the
balance of this TAF cycle, with IFR or lower stratus ceilings and
widespread rain and mist reducing visibility. HRRR shows numerous
rain showers, and perhaps embedded thunder, spreading eastward
across the airports through 12z Sun. Consensus of short term
models is for stratus to persist all day Sunday, with areas of
light rain and/or BR/DZ. More rain and embedded thunder is
expected Sunday night through Monday, with more poor aviation
weather expected. SE winds of 10-15 kts will continue through
Sunday morning, then trend NEly at similar speeds for the second
half of this TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 54 64 52 63 / 50 50 50 60
GCK 54 62 50 61 / 70 50 50 40
EHA 57 69 51 63 / 70 50 70 50
LBL 55 68 51 63 / 50 50 70 50
HYS 53 59 51 62 / 50 50 50 50
P28 54 65 56 65 / 50 50 50 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Turner
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1052 PM CDT Sat May 29 2021
.UPDATE...
Given the latest output from the 00Z HRRR and TTU-WRF showing
increased potential for showers and convection on Sunday, I have
elected to raise the PoPs slightly more into the 20 to 30 percent
range and expand mentionable PoPs further westward in areal extent,
including across the San Antonio metro area.
&&
.PREV DISCUSSION... /ISSUED 624 PM CDT Sat May 29 2021/
UPDATE...
Made slight adjustments to Sunday`s forecast including the high
temperatures and a small areal increase in the coverage area for
afternoon PoPs across the eastern half of the CWA. Adjusted the
grids into the evening regarding temperatures, dew points and
sky coverage based on satellite and observational trends.
AVIATION...00Z TAF package
VFR conditions will continue at the TAF sites this evening and
through much of the night. Clouds will thicken with time and
ceilings eventually lower to MVFR to IFR conditions during the
latter half of the overnight and into Sunday morning. Cannot
rule out some light fog as well at the aerodromes in the early
morning hours. Ceilings lift to VFR from late Sunday morning
into Sunday afternoon. Added VCTS for KAUS on Sunday afternoon
where sufficient moisture and lift could allow for isolated
convection, mainly east of US Highway 183. Winds remain east-
southeasterly of mainly light to moderate levels. KDRT may
gust as high as 25 mph on Sunday afternoon. MVFR ceilings will
likely redevelop at KAUS and KSAT during Sunday night.
PREV DISCUSSION... /ISSUED 213 PM CDT Sat May 29 2021/
SHORT TERM (Tonight through Sunday Night)...
Skies remain partly to mostly cloudy but the radar is mostly rain
free at the present time as the atmosphere remains worked over after
repeated rounds of convection between late yesterday afternoon
through this morning. 1 to 4 inches of rain was common across most
locations after everything came to an end. Latest high-res models
show an isolated shower or two across the area later this afternoon
and will continue with low PoPs to account for this, but with
temperatures remaining in the 70s and 80s, think this should be
about the best the atmosphere can do. As a result, the tonight
forecast should remain mostly dry. Lows overnight should be in the
upper 60s to lower 70s with continued cloud cover.
Isolated showers and perhaps a thunderstorm will remain possible on
Sunday, but anticipate most areas will stay dry. Highs will be in
the 80s for most locations. By Sunday night, the focus will turn to
the northwest for a complex of showers and storms expected in West
Texas. High-res models differ on the evolution of this system, but
there could be some threat that it would make it into our western
counties.
LONG TERM (Monday through Saturday)...
Our active stretch of weather looks to continue as we start the first
week of June 2021. Memorial Day could feature a few strong to severe
storms out west, as the Storm Prediction Center places areas along
and west of a Rocksprings to Brackettville to Eagle Pass line in a
Slight Risk. Areas along and west of of the I-35/I-37 corridor are
within the Marginal Risk area. The primary hazards will be isolated
large hail, along with damaging winds and heavy rain, which could
lead to additional flash flooding concerns given widespread heavy
rainfall over the last few weeks.
After Memorial Day, an upper level trough will slide eastward,
amplifying rather quickly, resulting in an upper level low getting
cutoff from the main upper trough over the northern Baja of
California. This will result in a series of shortwaves rippling
through the mid-level flow over South-Central Texas. As you may have
guessed, an active pattern will be the result of this setup, with
those disturbances sparking daily rain and thunderstorm chances once
again. It feels like we did this same scenario just last week.
Strangely enough, the GFS, ECMWF, and CMC are all in fairly good
agreement on this scenario, as well as the placement and overall
strength of the upper low through at least the THU/FRI timeframe. It
will be hard to pinpoint exactly who gets the heaviest rain and when,
however, with already swollen creeks, streams, and rivers, expect any
additional rainfall to exacerbate the flooding concerns into the end
of the coming week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 69 84 69 83 69 / - 30 - 30 30
Austin Bergstrom Intl Airport 68 84 69 84 69 / - 30 - 20 20
New Braunfels Muni Airport 70 85 70 86 70 / - 30 - 20 20
Burnet Muni Airport 68 81 68 81 67 / - 20 - 30 40
Del Rio Intl Airport 74 87 73 86 72 / 10 20 30 30 40
Georgetown Muni Airport 68 82 68 83 68 / 10 20 - 30 30
Hondo Muni Airport 70 86 70 86 70 / - 20 10 20 30
San Marcos Muni Airport 69 84 69 85 69 / - 30 - 20 20
La Grange - Fayette Regional 72 85 70 86 71 / 10 30 - 20 10
San Antonio Intl Airport 70 85 71 85 70 / - 20 - 20 30
Stinson Muni Airport 72 87 72 87 72 / - 20 - 20 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Brady
Long-Term...04
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
815 PM CDT Sat May 29 2021
.UPDATE...
Issued at 801 PM CDT Sat May 29 2021
Updated the forecast to remove any thunder from the forecast
before midnight. MUCAPE is weak, and effective 0-6 km bulk shear
is even weaker and expected to weaken over the next few hours,
along with rather marginal mid-level lapse rates. Chances for
thunder improve somewhat into the overnight hours, however.
&&
.DISCUSSION...(This evening through Saturday)
Issued at 219 PM CDT Sat May 29 2021
The holiday weekend will be cool with pesky rain/thunderstorms,
but fortunately the severe threat remains very low.
Today, skies remain mostly cloudy over most of central Nebraska and
partly cloudy over northern Kansas. Near-term models show that
precipitation will not arrive until late tonight ahead of upper
level trough axis moving through the area. The RAP initially shows
100-500 J/kg of MUCAPE...enough for a few rumbles of thunder but
not for any strong/severe storms.
Scattered showers and perhaps a few thunderstorms will linger
through Monday morning before gradually decreasing in coverage and
intensity Sunday afternoon. In total, the latest ensembles show
0.50- 1.50" of rain across the area tonight through Sunday. This
could lead to minor rises on area creeks/rivers, but rainfall
rates should be low enough to avoid flooding issues.
On Memorial Day, some light showers may linger across southern
portions of the area, but skies should gradually clear from north
to south. Areas along/north of I-80 have a good shot at reach the
low/mid 70s by late afternoon. Winds will be easterly and fairly
light.
There is one more slight chance for showers on Tuesday as another
upper perturbation moves through. After that, we will see a dry and
warming trend through the end of the week as upper level ridging
pushes overhead. Highs will likely approach 90 degrees in some spots
by Friday and Saturday.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 657 PM CDT Sat May 29 2021
Biggest issue will be ceilings lowering to the cusp of IFR/LIFR by
late tonight/early Sunday. VCTS may be overdoing it for KEAR this
evening, but just enough instability to warrant some thunder
mention this evening. Better chance of thunder overnight.
Visibility could be reduced overnight/Sunday morning with some
convection that produces at least moderate rain.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Heinlein
DISCUSSION...Mangels
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Marquette MI
639 PM EDT Sat May 29 2021
.SHORT TERM...(This evening through Sunday)
Issued at 412 PM EDT SAT MAY 29 2021
WV imagery and RAP analysis indicated a mid/upper level trough from
Northern Manitoba into eastern Montana and a downstream ridge from
Iowa through western Lake Superior to James Bay. At the surface, a
ridge extended from northern Quebec through the western Great Lakes
with a very dry airmass in place over the region. A trough
stretched through the central Dakotas. Some patchy cirrus was
spreading into western Lake Superior with WAA developing ahead of
the trough. Afternoon mixing has dropped dewpoints into the mid 20s
to around 30 inland.
Tonight, another night with PWAT values to around 0.20 inch and
clear skies will result in favorable radiational cooling. As the sfc
ridge shifts off to the east, some increase in southerly winds are
expected but will be weak enough so that winds inland remain
decoupled. Increasing clouds late over the west could also limit the
cooling. Over the rest of the area, temps should drop into the lower
30s inland with areas of frost developing in typical cold spots.
Weak downslope flow will keep temps in the lower 40s closer to Lake
Superior.
Sunday, a shortwave ahead of the mid level trough may support some
light showers into the west half. However, with the antecedent dry
airmass and minimal moisture inflow, little rain is expected with
likely more virga. So, only low end chance POPs are included.
Otherwise, mixing with partly to mostly sunny skies over the east
half will drop dewpoints into the mid 20s to around 30 resulting in
RH values from 20-30 pct. With south winds gusting into the 15 to 20
mph range, elevated wildfire conditions are expected.
.LONG TERM...(Sunday night through Saturday)
Issued at 428 PM EDT SAT MAY 29 2021
For the long term forecast, we can expect an active weather pattern
with a couple of shortwave disturbances trekking across the Great
Lakes, and a gradual warming trend to continue. The CPC 8-14 Day
Outlook looks to have an above average trend for temperatures
favored, and near normal chances of average precipitation for the
Great Lakes area. Given the current deterministic output for the
extended forecast period into next weekend, upper level ridging will
be present and several areas may see afternoon highs approaching 90
degrees for the interior portions of Upper Michigan. This could be
record warm temperatures territory to end the first week of June.
From Sunday night into Monday, a shortwave will strengthen into a
shortwave trough further upstream over Manitoba and Ontario. This
shortwave will be in a favorable region for upper level dynamics to
assist with showers and convective development for Monday afternoon.
SPC has a Marginal Risk for Day 3 over the west half of Upper
Michigan, so we will have to monitor that area closely in the
upcoming 48 hours. At this time, MUCAPE values are between 1000-1500
J/kg near the MI/WI state border for the Monday afternoon period
where the convection is favored, but shear isn`t all that strong.
Trending toward a possible wind event with any downbursts from
thunderstorm cores. Still a skinny CAPE profile nonetheless, so
convection isn`t expected to become widespread at this time of
analysis. Much needed rainfall will be appreciated for Upper
Michigan on Monday, despite it putting a damper on the holiday for
several folks that may be outdoors.
The base of the trough axis will swing out of the Great Lakes area
by Tuesday, and be replaced by weak upper level ridging. This will
allow temperatures to rebound nicely for afternoon highs on Tuesday
across the cwa where low to mid 70s are likely. Another shortwave
disturbance will approach the Great Lakes on Wednesday, bringing
another opportunity for rain showers over the area. Timing and
placement of the shortwave is not in agreement well, with the GFS
bringing the most aggressive output for rain showers and possible
convection over Upper Michigan. This might be the best chance of
more widespread rain and thundershower activity for the week.
Southerly flow will assist with afternoon highs being slightly
warmer on Wednesday, where temperatures up to the Lake Superior
shoreline could reach the lower 70s, and near 80 further inland.
Kept PoPs at slight chance to chance because model agreement still
not in place at this time. Another shortwave will move through on
Thursday, bringing the opportunity for afternoon diurnal
showers/convection to the area, but the potential remains low for
total rainfall at this time.
Friday and into the weekend will bring an amplifying upper level
ridge over the central CONUS toward the Great Lakes. Extended model
guidance is hinting at very warm temperatures being possible over
Upper Michigan, possibly the warmest temperatures of the season thus
far. 850mb temperatures are signaling outputs in the +20C to +23C
for the weekend. This combined with southerly flow would easily mix
down to the surface and bring afternoon highs in the middle to upper
80s, with potentially 90+ degrees if cloud cover remained minimal
over the interior portions of the Upper Peninsula. We will continue
to monitor the extended period in the event that models continue to
agree and show the warm temperatures across the region becoming more
likely.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 639 PM EDT SAT MAY 29 2021
VFR conditions are expected to prevail through this TAF period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 412 PM EDT SAT MAY 29 2021
No real marine concerns as winds of 20 knots or less are expected
into next week. High pressure to the northeast will be the dominant
force over the region through the rest of the weekend. Late Monday,
a weak cold front will swing through the region and could produce
showers and maybe a few thunderstorms, but will then be replaced by
more ridging and dry weather by midweek.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Frost Advisory from 1 AM EDT /midnight CDT/ to 7 AM EDT /6 AM
CDT/ Sunday for MIZ005>007-010>014-085.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...BW
AVIATION...07
MARINE...JLB
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 310 PM CDT Sat May 29 2021
Precipitation chances and timing should provide the main forecast
challenges the next few days.
Large scale pattern at 850 mb shows a ridge with a cool airmass
over the Great Lakes region, which extends southwest down across
IA and toward OK. Highest moisture content at that level was from
north TX into western KS. Farther aloft, at 500 mb, a trough
extended from northern Saskatchewan down toward WY. Main height
falls with this were well to the north of our area. There was a
another mid level system with a weakly closed off low in southern
CA. Weak height falls will continue tonight mostly across the
Dakotas and MN, with weaker falls over our area later tonight and
Sunday.
Will keep rain chances going this evening in northeast NE, and
then stay with the trend of increasing POPs later tonight farther
to the east toward Omaha and Lincoln. Generally used a blend of
the recent HRRR runs along with some of RAP and GFS. The HRRR
seems to the most bullish in moving precipitation eastward late
tonight. Not completely sure that is right, so that is why we
stayed with a model blend as mentioned. Look for lows tonight from
the lower 40s to near 50. Heaviest rain tonight should be from
western KS into central NE.
Sunday...remnants from whatever develops tonight should try to
push across our area on Sunday. Kept chances highest in the
morning for the whole area. Chances from about mid morning into
the afternoon should be highest from Albion and Columbus toward
Lincoln and Beatrice. Trended POPs slightly lower across the area
for Sunday night, except in Nebraska south of I-80 late. Both the
12Z GFS and ECMWF show potential for rain amounts of 0.25 or more
late Sunday night and Monday along the KS border as some lift
moves in from the southwest. Mid level trough should push through
Tuesday night, turning our winds at 500 mb to the northwest.
Tuesday and Wednesday.
This period looks mainly dry, except will keep some low POPs
Tuesday near the KS border and for about the eastern half of the
forecast area Wednesday. High temperatures should be in the 70s
Wednesday and then mid 70s to around 80 Wednesday.
Wednesday night into Saturday.
This period also looks dry or mainly dry. Model agreement starts
to decrease at bit with the large scale pattern, especially toward
Saturday. A ridge aloft should build toward the Plains, while a
closed low stays back toward northern Baja CA. In the low levels,
southerly flow will increase. Temperatures should top out mostly
in the lower and mid 80s Thursday, with mid 80s to around 90 both
Friday and Saturday. Pattern could start to turn more active by
Saturday afternoon or evening.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 624 PM CDT Sat May 29 2021
Patchy ceilings around 3,500 ft AGL and a few showers are
possible over northeast Nebraska through 06Z Sunday. Otherwise
unrestricted visibility and ceilings around 10,000 ft AGL should
prevail through 06Z. Rain shower activity should increase after
06Z, with the peak rain potential at KLNK and KOMA between 15Z and
21Z Sunday. Ceilings in the 1,500 to 3,500 ft AGL range should
accompany any shower activity. Improving conditions are expected
after 21Z Sunday. Winds should remain light (10 kt or less)
through 00Z Monday.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Miller
AVIATION...Albright
Area Forecast Discussion
National Weather Service Phoenix AZ
450 PM MST Sat May 29 2021
.UPDATE...Updated Aviation discussion.
&&
.SYNOPSIS...
Seasonable dry and warm conditions under mostly clear
skies are expected across the lower deserts through Memorial Day.
High temperatures will mostly top out in a 99-102 degree range
through the holiday weekend with readings likely a bit warmer for
the middle of next week. A slight increase in moisture across
eastern Arizona later next week may be enough for some isolated
thunderstorms primarily over the higher terrain. An isolated shower
or thunderstorm can not be entirely ruled out for the Phoenix area
later next week.
&&
.DISCUSSION...
The upper level RAP analysis depicts W-SW flow aloft in advance of a
coastal-S CA weak UL shortwave disturbance and PVA anomalies. METSAT
imagery had clear skies over the area with a high cloud shield just
NW of the area moving NE in advance of the S CA disturbance. Further
N of the disturbance was a large amplitude Coastal PAC-NW ridge
building into W Canada. Mid-level WV imagery also showed a swath of
slightly elevated moisture moving E across the area in advance of
the S CA disturbance.
A 3rd day of the late week warming trend will continue today with
highs topping out in Phoenix and the lower deserts in the low 100s.
Models now agree on the negatively tilted open wave trough beginning
to dig SSEwrd tonight into offshore Baja while reorienting into a
positive tilted UL low. Tomorrow the base of the low digs further S
to offshore S-central Baja and on Monday an open wave trough axis
extends NE from the GOC across SW to NE AZ. This could steer smaller
weak vort max(S)disturbances from the base of the low across SE AZ
early Mon. Although the weak low is mostly moisture challenged it
will drop heights enough to allow for a very slight dip in temps
with highs near 99-101 for Sunday and Memorial Day Monday
For Wed the Clusters forecast analysis agree on maintaining the low
as a cut-off low over N-central GOC. They continue to agree on the
strong W US ridge peaking in strength on Wednesday, with the ridge
axis over N-central CA to the N Rockies. This creates a temporary
Rex Block pattern. And there is still good agreement on the ridge
shifting to the east and flattening on Thu and Fri while the
trough lingers in place. For QPF chances for Tue through Fri the
Clusters still show at least one minor cluster favoring very minor QPF
each day which is an indication of slight chances of very isolated
showers or high-based thunderstorms.
However the much more likely and bullish solution favored by the
Clusters is still dry conditions associated with the strong
midweek high pressure building in from the northwest and
associated mid-week warm up to near 103-105 degrees on Wed and
Thu. Still, the GEFS plume PW moisture continues to gradually
increases from near 0.65 Mon to near 0.9 late in the week
associated with the weak low lingering to the S or SW. The end
result are very low-end POPs near 10-15% for Phoenix for much of
the week and into next weekend. Much more likely for the lower
deserts would be gusty outflow winds from isolated thunderstorm
over higher terrain east of Phoenix. For S. Gila cty and the Tonto
Basin isolated thunderstorms will also be capable of producing
dry lightning, gusty winds and little to no rainfall.
So the indications are that the midweek warm-up resulting in areas
of moderate heat risk will likely be reigned in by increasing
moisture and decreasing high pressure during Thu and Fri which
would mitigate an excessive heat event as temperatures settle back
to near 101-103 late this week and into the weekend.
&&
.AVIATION...Updated at 2350Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Breezy conditions will persist early this evening before winds
subside around 03-04z. Winds will then generally follow typical
diurnal tendencies through Sunday. However, westerly winds will be
somewhat lighter Sunday afternoon than those observed today.
Southeast California/Southwest Arizona including KIPL and KBLH:
A weak low pressure system across southern California will result
in breezy conditions this evening. Winds will then subside
overnight as the low lifts northeastward and the pressure gradient
weakens. Another low pressure system will move southeastward
towards the Baja Peninsula Sunday afternoon. However, with a track
south of KIPL and KBLH, winds will be considerably weaker than
those observed today.
&&
.FIRE WEATHER...
Tuesday through Saturday:
Weak upper level troughing will remain near the region with high
pressure increasing by Wed. Expect max temps to remain slightly
above normal through the entire period. A gradual increase in
moisture during the period is likely to bring some isolated
thunderstorms across the AZ high terrain, with lower desert storms
not entirely out of the question though much less likely. However,
wetting rains are not very likely, so these isolated storms may
pose a dry lightning threat. Min RH values will remain quite low,
mostly staying between 7-12% each day. Daily max RHs will mostly
range from 25-45% with higher readings across the western deserts.
Winds will remain light to moderate through the bulk of the
period, but with typical afternoon breeziness most days.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...Hirsch
FIRE WEATHER...Sawtelle/Kuhlman
Area Forecast Discussion
National Weather Service San Diego CA
107 PM PDT Sat May 29 2021
.SYNOPSIS...
Our cooler than average Spring weather will persist through Sunday
as onshore flow and a fairly deep marine layer prevail west of the
mountains. Gusty late day and evening westerly winds will continue
through the passes and into the deserts one more day, even as the
high deserts begin to warm. The warming will spread across the
southern deserts on Memorial Day, with above average temperatures
expected through the middle of next week. West of the mountains,
the marine layer will shrink, but continue to moderate temperatures
over the valleys and along the coast through next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Marine layer clouds had shrunk back to coastal areas by midday,
leaving skies mostly clear. moderate onshore sfc pressure gradients
were holding to the deserts, where some wind gusts to around 35 MPH
were reported locally into the deserts.
Marine clouds were holding over he CA Bight at midday, along with a
weak eddy circulation. Those clouds will move back inland later
today and spread will inland again overnight. Some patchy drizzle
could redevelop again, especially over coastal areas where the
latest HRRR model runs continue to depict some very light, spotty
accumulations.
A weak upper-level trough will drift SE over SoCal thrugh Sunday,
maintaining a fairly deep marine layer and gusty onshore flow into
the deserts at times. That trough will settle south into NW MX and
cut off a weak upper low, which will turn our upper-level winds
from the east, and return some higher clouds and humidity aloft.
Meanwhile a ridge will poke east across NoCal from the Pacific
through midweek, almost forming a weak Rex Block over the State by
Wednesday. This proves to be temporary though, as the westerlies
across the North Pacific reclaim territory across the PacNW and
weaken the ridge. The upper low to the south moves little,
continuing the E-NE winds aloft over SoCal, and periods of high
clouds into next weekend.
It is a pretty quiet pattern overall for us, but it will be warmer
most areas next week with daytime temperatures averaging about
normal for coastal areas, and from 4-9F above average inland. The
warmer weather is confirmed by a majority of the 12Z ensemble
members of the major global models. By next weekend, into the
following week, there is more uncertainty as the ECMWF solutions
hold onto the warmer weather longer, while the GFS/CMC runs turn
cooler.
&&
.AVIATION...
291930Z...Coast/Valleys...Areas of SCT-BKN low clouds with bases
1500-2500 ft MSL near the coast will intermittently clear through
the afternoon. Low clouds will begin to spread back inland after 00Z
Sun, reaching KONT/KSBD around 10Z Sun. Low cloud extent should fill
in the coastal basin overnight. Local vis restrictions of 3-5 miles
in the valleys and where clouds intersect higher coastal terrain.
Cigs will be 1000-2000 ft MSL. Scattered conditions will return 17-
19Z Sun.
Mountains/Deserts...Mostly clear with unrestricted vis through
tonight.
&&
.MARINE...
Wind gusts periodically reaching 20-25 knots expected near San
Clemente Island through tonight. Otherwise, no hazardous marine
weather is expected through Friday.
&&
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...10
AVIATION/MARINE...CO
Area Forecast Discussion
National Weather Service Las Vegas NV
135 PM PDT Sat May 29 2021
.SYNOPSIS...Isolated showers and thunderstorms are possible this
afternoon and early evening over the Sierra, which could result in
gusty winds for the Owens Valley. Otherwise, relatively quiet
conditions with minor afternoon breezes and above normal
temperatures can be expected for the Memorial Day Weekend.
Temperatures will approach record highs for the latter half of the
upcoming week due to persistent high pressure over the region.
&&
.DISCUSSION...Forecast problem for this afternoon and evening will
be thunderstorm potential over the Sierra and resultant outflow
winds possibly pushing further east. Satellite loop showed cumulus
bubbling over the central and southern Sierra early this afternoon,
as well as the White Mountains just north of the Inyo county line.
Mesoanalysis showed MUCAPE of just over 500 J/kg and about 700 J/kg
of DCAPE along the west side of the Sierra crest, with about 50-100
J/kg of CIN keeping a lid on things as of 1 PM. RAP model forecasts
at 4 PM are quite interesting, with 800 J/kg of SBCAPE, zero CIN,
and an axis of ~1000 J/kg of DCAPE stretching east across Bishop,
through Esmeralda county and into central Nye county. This suggests
that if any downdrafts are able to make it to the east side of the
Sierra crest, gusty winds would likely make it down to the Owens
Valley floor, and similarly, any downdrafts on the east side of the
White Mountains could push through Esmeralda county. Confidence in
whether or exactly where this will occur is too low to include
specific wind forecasts in the grids, but will continue to monitor.
Convection should die off shortly after sunset with the loss of
daytime heating, but an outflow or two may persist longer. The weak
mid level trough which is helping generate storms this afternoon
will move very slowly east tonight and tomorrow, with very small
chances for showers tomorrow in the Sierra and also on the eastern
CWA border near Colorado City tomorrow and Monday. By then, heat
will be taking over as the main problem as high pressure noses in
from the east Pacific. The area of moderate heat risk increases over
the deserts starting Sunday, with high risk areas appearing in Death
Valley Tuesday and expanding Wednesday and Thursday. The first 100
degree day of the season at KLAS is likely to be Monday or Tuesday,
and Thursday is expected to be the hottest day of the week with KLAS
nearing 105 and Death Valley between 115 and 120.
&&
.AVIATION...For McCarran...In general, winds should remain light for
much of the afternoon with upticks in speed to 8-10 knots most
likely originating from the east to southeast. After 23z, southeast
winds will prevail at speeds of 9-13 knots. Gusts of around 20 knots
will be possible through around 04z after which winds will turn
southwest at 10 knots or less through late tonight. Light, diurnal
wind trends expected for Sunday. Shield of high clouds currently
over the area will clear out quickly after 22z.
For the rest of southern Nevada, northwest Arizona and southeast
California...Most areas will see a light breeze out of the south
this afternoon with gusts up to around 20 knots. Winds decrease this
evening and favor diurnal trends into Sunday. The exception will be
KDAG where winds favor a more westerly direction with speeds of 15-
20 knots gusting around 25 knots this evening. KBIH will be
interesting today as storms develop over the Sierra and to the north
of Bishop this afternoon. These storms will most likely not affect
the terminal directly but could push strong north winds down the
Owens Valley. Best chances for these strong outflow winds look to be
between 00z-04z this evening with estimated wind speeds of 10-20
knots gusting 20-30 knots. The cloud shield currently over southern
Nevada and northwest Arizona will continue to shift northeastward
through tonight.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Morgan
AVIATION...Guillet
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