Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/03/21
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
700 PM CDT Sun May 2 2021
.AVIATION...
For the 00Z TAFs, a cold front will move across the area this
evening with gusty north winds in its wake. A cluster of showers
and tstms will track east across parts of the OK Panhandle this
evening, and have included VCSH at KGUY for a few hours. MVFR cigs
are then forecast to develop at KGUY, KDHT, and KAMA late tonight
through the end of the fcst cycle. Scattered light rain showers
are also possible late tonight into Monday.
02
&&
.PREV DISCUSSION... /Issued 256 PM CDT Sun May 2 2021/
SHORT TERM...Tonight through Tomorrow Night...
19Z WV satellite shows a longwave trough over the Rockies with jet
streak on the equatorward side of this feature over the southern
AZ/NM USA-Mexico border. A weak shortwave is seen to our west over
Colfax County with some cumulus development ongoing ahead of this
feature. At the surface, low pressure has developed under the left
exit region of the upper jet in Cimarron County, with a dryline
extending southward from this feature through western portions of
Sherman, Moore, Potter, and Randall Counties, separating areas with
dewpoints in the mid 20s to the west and dewpoints around 50 to the
east.
This afternoon into early this evening, a few thunderstorms may
develop in the OK Panhandle as the NE NM shortwave approaches the
dryline. HRRR/NAMNest/NMM/ARW all suggest at least a storm or two
will develop. The RAP is less bullish, depicting less instability
overall. That being said, have discounted RAP solutions as modeled
dewpoints have come in consistently below observations east of the
dryline, suggesting instability parameters are underdone in this
model. Given mid level lapse rates of 8.5 C/km or greater and the
overall improvement in hodograph curvature, do think that hail
remains a potential hazard. Additionally, DCAPE of around 1000 J/kg
would promote a risk for damaging wind gust. Despite the
aforementioned improvement in hodograph curvature, continue to think
that the tornado risk is very low given LCLs above 3000m.
Tonight into tomorrow night, surface low shifts to the east and a
cold front pushes south through the Panhandles. Progged saturation
seen at 850/700mb suggests widespread cloudiness will follow the
front, so have gone with the low end of consensus blends for
temperatures Monday. These saturated profiles will also allow for a
chance for showers and maybe a rumble of thunder or two. As the base
of the trough approaches Monday afternoon, shower coverage should
increase a bit. That being said, overall progged moisture depth has
trended downward over the past few days of model runs, so optimism
continues to wane as the event trends toward a typical post-frontal
shallow moisture setup, which usually yields highly disappointing
precip amounts and spotty coverage. Have thus generally leaned below
NBM PoPs for Monday, leaving mainly likely mentions across the
forecast area during the early afternoon.
Ferguson
LONG TERM...Tuesday through Saturday...
The extended is mostly dry with some possible fire weather
towards the end of the week into the weekend.
Tues morning will see the upper level trough shift eastward and
the cold front push into southeast TX, leaving the Panhandles dry
as high pressure fills in. By Tuesday evening the high pressure
spreads eastward and allows surface winds to become southerly.
Wednesday will see a shortwave cross the northern Plains and have
an inverted trough with an associated cold front. The cold front
should push into the Panhandles. There is some moisture with the
front that may bring precip to KS, but by the time it gets to the
Panhandles, the moisture may be too lacking to bring precip and
be just clouds. High pressure fills in again for Thursday with mid
level height rises. Long range models show the next low pressure
system start to dive southeastward into the Pacific northwest on
Friday. This will help shove the ridging over the western CONUS
eastward over the Rockies and bring shortwaves to the Panhandles.
Some models indicate precip chances could be possible Friday
evening, but NBM is running dry with this run. Likely this is due
to timing differences between models, so for now have left things
dry until more consistency on the timing of moisture and waves can
come together. NBM does have precip chances in the southern Plains
for Saturday as more moisture will be present for the next cold
front which looks to be over the weekend sometime.
Beat
FIRE WEATHER...Tuesday through Saturday...
Tuesday, Wednesday, and Thursday could see some very spotty
elevated fire weather conditions generally for RH around 20
percent and winds around 20 mph in various parts of the Panhandles.
Friday and Saturday will be the "bigger" deal with a majority of
the Panhandles having possible elevated to critical fire weather
conditions. Friday will still have RH around 20 percent with some
spots dropping to near 15 percent. Winds will be a bit stronger,
getting upwards of 20-30 mph. RFTI values will generally be 2 with
some 3s. Saturday looks to have RH drop to single digits in the
west and near 20 percent in the east. Winds will again be 20-30
mph and RFTI values will be from 0 in the east to 5-6 in the west.
With no appreciable precip in the extended, ERC values are
forecast to be around the 80-90th percentile. Temps on Saturday
will be near 90 degrees with the LLTR reaching up through the
TX/NM state border. Jets are not looking stacked or much in the
area, so not looking for strong winds.
Beat
&&
.AMA Watches/Warnings/Advisories...
TX...Red Flag Warning until 10 PM CDT this evening for the following
zones: Armstrong...Deaf Smith...Hartley...Oldham...Palo
Duro Canyon...Potter...Randall.
OK...None.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
636 PM CDT Sun May 2 2021
.SHORT TERM...(This evening through Monday)
Issued at 225 PM CDT Sun May 2 2021
The cold front was making very slow southward progress across the
area early this afternoon, stretching from southwest Minnesota into
central Wisconsin. With a somewhat baggy gradient in the vicinity of
the front, the wind flow and resulting moisture return in the warm
sector has been rather slow. Upper 50s to around 60 dew points were
just starting to approach the area and most of the area south of the
Interstate 90 corridor should see at least upper 50s by late
afternoon. The RAP suggests this will result in about 1000-1500 J/kg
of ML CAPE being in place. As a short wave trough currently moving
across South Dakota and Nebraska interacts with the front, showers
and storms are expected to develop along the front starting late
this afternoon and then should grow into a pretty solid line of
activity by early evening. The best deep layer shear will reside
north of the front but around 20 to 25 knots in the 0-3km layer
should be in place over the front. This may pop up to around 30
knots at times which could be enough to support some strong storms
with gusty winds and small hail.
With the flow staying out of the southwest overnight, additional
short wave troughs are expected to move over the region. The forcing
from these waves combined with a band of weak frontogenesis in the
850-500 mb layer will help to keep the showers going in the
baroclinic zone overnight. The coverage may become a bit more
scattered Monday morning in a diurnal minimum before picking back up
again in the afternoon as some CAPE returns in the warm sector. The
threat for a strong storm looks even lower Monday with less shear in
place. In general, the activity and front will get a push to the
southeast during the day Monday as a stronger northern stream short
wave trough advances out of Canada into the Upper Midwest.
.LONG TERM...(Monday night through Sunday)
Issued at 225 PM CDT Sun May 2 2021
Any lingering rain will move out of the area Monday evening as the
cold front continues to push eastward and weak surface ridging
builds into the upper midwest. Upper low over Ontario will
initially drive the weather over the northern US this week.
Quasi-zonal flow over the Upper Mississippi Valley and weak
surface ridging Tuesday and Wednesday will lend itself to below
normal temperatures. Then Wednesday night into Thursday, a long
wave ridge builds over the west coast, amplifying the flow over
the plains. Meanwhile, a short wave will drop into the Mississippi
Valley, bringing another weak front and chance of showers
Wednesday night into Thursday. By the weekend the upper ridge
flattens, and another surface low is progged to develop and move
east across the central US. Given the generally zonal pattern,
confidence is low on the particulars by late week. Generally
though, the signals are for near to slightly below normal
temperatures and another period of rain next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 636 PM CDT Sun May 2 2021
Main taf concern is thunderstorm chances through tonight then IFR
condition at both taf sites late tonight into Monday. A cold
front extending from central Wisconsin into western Iowa will be
the focus for periodic showers and a few thunderstorms through
tonight. Current showers/storms that are impacting the taf
sites... will diminish over the next couple of hours.
Then...expect some redevelopment of showers and possibly a few
storms to move across the area during the night time hours. With
the cold front over the region ceilings will lower into IFR at
both taf sites after 06z Monday and prevail through much of the
taf period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...04
LONG TERM...DMD
AVIATION...DTJ
Area Forecast Discussion
National Weather Service Denver/Boulder CO
730 PM MDT Sun May 2 2021
.UPDATE...
Issued at 709 PM MDT Sun May 2 2021
Latest HRRR models runs were trending colder in the foothills,
which will translate to a lowering of snow levels and expected
snowfall. Main concern will be for areas in the foothills above
7500 feet, so have gone ahead an issued a Winter Weather Advisory
for this area from midnight tonight through 6 pm Monday evening.
Heaviest snowfall will likely occur late tonight through midday
with expected storm totals anywhere from 4 to 10 inches. Strong
thunderstorms continue to develop this evening with the focus for
the strongest storms shifting south and east of Denver at least
over the next hour or two. Cold front has also pushed through
Denver 6-7 pm this evening, accompanied by wind gusts to 40 mph.
Stronger winds will weaken this evening and become more
northeasterly overnight. Deepening upslope should then focus more
of the precipitation on locations in and near the Front Range
mountains, foothills and Palmer Divide later tonight into Monday.
&&
.SHORT TERM...(This evening through Monday)
Issued at 242 PM MDT Sun May 2 2021
Scattered thunderstorms from late today and early this afternoon
are moving off east to Kansas and Nebraska. It looks like there
could be another round of convective storms through the rest of
the afternoon and early evening, and a Severe Thunderstorm Watch
remains in effect for much of the plains through 7 PM MDT.
Precipitation will become more stratiform behind a stronger front
in the early evening. Continue to expect widespread precipitation
falling as mostly snow in the mountains and higher foothills and
rain across the plains and lower foothills, with a mix in between
at elevations roughly 7000 to 8000 feet. The Winter Weather
Warning for the Front Range Mountains remains in place for tonight
through Monday evening as heavy snowfall is still expected along
and east of the Continental Divide driven by deep and persistent
upslope flow, accumulating 7 to 14 inches through that period. We
have also issued a Winter Weather Advisory for the Park and Gore
Ranges from 6 PM this evening through 6 PM Monday evening, focused
on the Park Range in Jackson County specifically above about 9000
feet where forecast precipitation has increased and to snowfall
of 6 to 12 inches.
High temperatures today will be cooler behind the fronts, in the
mid 60s to mid 70s F on the plains. Lows tonight will also be
cooler but should be insulated by mostly cloudy to overcast skies
overnight, with lows in the low 40s F on the plains and upper 20s
to mid 30s F in the mountains. Expect widespread showers to
continue through Monday under overcast skies.
.LONG TERM...(Monday night through Sunday)
Issued at 242 PM MDT Sun May 2 2021
By Monday night the upper level trough will be in place over eastern
CO. Moisture and weak northeasterly upslope will continue along the
foothills into the evening hours on Monday keeping light snow over
the higher terrain and some rain possible along and west of I-25.
Northwesterly flow will push in behind the trough with the surface
low moving into southeast CO pulling in drier air from the north.
This will help to bring precipitation to an end through Tuesday
morning. The continued northwest flow will keep conditions on the
cooler side for Tuesday with highs in the upper 50s to lower 60s. A
weak shortwave embedded in the flow should be able to feed off the
residual moisture in the area and with enough orographic lift
produce scattered showers over the higher terrain by Tuesday
afternoon that could move over the lower elevations Tuesday evening.
Yet another shortwave in the flow aloft will move through Wednesday
mainly tracking over the northern portions of the CWA bringing
isolated to scattered showers to the northeast plains counties
Wednesday afternoon. Temperatures will start to see a rebound by mid-
week with highs getting back into the 60s.
A ridge will build in Thursday bringing dry conditions for Thursday
and most of Friday with just a slight chance of some showers for the
northern mountains Friday afternoon. This is due to increased
moisture and lift ahead of the next trough. Temperatures are
expected to warm back into the 70s and possible lower 80s by Friday
with southwest surface flow and 700 mb temperatures approaching 12C.
At this time it appears Saturday will remain dry with a chance of
showers Sunday depending on where the upper trough moves.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 709 PM MDT Sun May 2 2021
Prevalent MVFR ceilings expected tonight into Monday morning, with
intermittent IFR conditions with periods of stronger precipitation.
Winds should remain generally north to northeast through the period.
Gusty winds associated with the cold front and nearby thunderstorms
will weaken to 10-15 kts overnight. Ceilings will gradually improve
ILS restrictions Monday afternoon, as the focus for heavier
precipitation shifts south.
&&
.HYDROLOGY...
Issued at 242 PM MDT Sun May 2 2021
Heavier rainfall from thunderstorms late this afternoon has
shifted to the south and east of the burn scars early this
evening. We still expect the precipitation will become more
stratiform with light to moderate rain which will persist through
Tuesday morning. The higher foothills, above 7500 feet, and
mountains and portions of the burn areas there will see snowfall
and decreasing potential for flooding. The highest potential for
flooding would then be over the Calwood burn scar as there may
heavier rainfall through the night. No flash flood watches are
planned at this time, but we will continue to monitor the area
closely.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 6 PM MDT Monday
for COZ035-036.
Winter Storm Warning until midnight MDT Monday night for COZ033-
034.
Winter Weather Advisory until 6 PM MDT Monday for COZ031.
&&
$$
UPDATE...Cooper
SHORT TERM...Direnzo
LONG TERM...Bowen
AVIATION...Cooper/Direnzo
HYDROLOGY...Direnzo
Area Forecast Discussion
National Weather Service Charleston SC
927 PM EDT Sun May 2 2021
.SYNOPSIS...
High pressure will extend across the region through tonight. A
series of storm systems could then bring unsettled weather
through mid week before a cold front crosses the region late
Wednesday into Thursday. Dry high pressure should prevail next
weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Surface streamline and observations trends show the warm front
remains situated northwest-southeast across central Georgia into
far Southeast Georgia at 03/01z. The front is beginning to move
slowly northeast and will move across Southeast Georgia,
southern South Carolina and eventually the Charleston Tri-County
area overnight. The overall forecast philosophy has changed
little from the previous update. There will be a continued risk
for isolated to scattered showers/tstms overnight ahead of the
warm front with the best juxtaposition of isentropic ascent,
theta-e advection and instability occurring over the Charleston
Tri-County area, especially along the Charleston County coast.
Pops were adjusted slightly to expand the chance pops around 30%
a bit more per going RAP/H3R trends. Lows in the upper 60s/lower
70s still look on track.
RAP instability profiles show SBCAPE values reaching as high as
1500-2000 J/kg across much of southern South Carolina overnight
(highest in Charleston County) as low-level moisture increases
from off the Atlantic and mid-level lapse rates cool ahead of
the warm front. The combination of modest 0-6km bulk shear and
some low-level helicity (0-1km ~200 m2/s2) could yield a window
where an isolated strong to severe tstm could form, mainly
across the Charleston Tri-County area. This potential will be
closely monitored overnight.
It will be a warm/humid night for May with lows only dropping
into the upper 60s/lower 70s.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Monday: A low pressure system will track across the Midwest with h5
shortwave energy rounding its southern periphery, eventually
traversing much of the Southeast and Mid-Atlantic states during the
day. This shortwave activity along with increasing levels of
moisture (PWATs around 1.5 inches) within a southerly sfc wind
should support few/scattered showers and thunderstorms late morning
into the afternoon. Temps should also be a few degrees warmer than
the previous day as breaks in clouds occur and a southwest flow
prevails along the fringes of a mid-lvl ridge centered off the
Southeast Coast. In general, highs should peak in the mid/upper 80s
across southeast South Carolina to around 90 degrees away from the
coast in southeast Georgia. Conditions are expected to remain dry
overnight with the loss of diurnal heating and forcing well to the
north. Lows will remain mild, ranging in the upper 60s inland to
lower 70s closer to the coast.
Tuesday: A fairly warm day is expected with a southwest flow in
place along a large ridge of high pressure centered across the
Caribbean and western Atlantic. Temps should be the warmest of the
week, peaking in the lower 90s inland while remaining in the low/mid
80s closer to the coast. A large/broad trough should advance across
the Central United States during the afternoon with leading h5
shortwave energy entering the Southeast mid-late afternoon into
evening hours. Forcing along with slightly deeper moisture than the
previous day (PWATs 1.50-1.75 inches) should support few to
scattered showers/thunderstorms arriving later in the day with
greatest coverage anticipated well inland late day before activity
slowly transitions toward the coast overnight. Another mild night
will be in place with a light southwest wind under increasing
clouds. In general, lows should remain in the upper 60s inland to
lower 70s closer to the coast.
Wednesday: A broad mid-upper lvl trough will slowly advance towards
the Eastern Seaboard with an associated cold front, forcing a broad
ridge further south of the area. Deep moisture and forcing will
likely support scattered to numerous showers/thunderstorms across
the local area, with convective activity generally expected to
remain sub-severe and mainly away from the coast during the day.
Cloud cover and precip activity should limit overall sfc heating
potential, with highs generally ranging in the mid/upper 80s.
Despite some limitation to overall heating, 35-40 kt low-lvl wind
fields in advance of the approaching front should support breezy
conditions late morning through afternoon hours, with southwest
winds gusting upwards to 15-25 mph at times.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Scattered to potentially numerous shower and/or thunderstorms are
possible across the area Wednesday night, with activity generally
expected to remain sub-severe as a cold front shifts offshore. Few
to scattered showers and thunderstorms could persist into Thursday,
depending on the overall south-southeast progression of the front
and low pressure traversing along it. There are also indications
that a secondary front could shift through the area late Thursday
into early Friday, but confidence remains somewhat low this feature
will produce additional precip activity. Dry high pressure should
arrive by late Friday morning, then prevail through the weekend. In
general, high temps should cool post fropa into the mid-upper 70s
Friday, before gradually warming into the upper 70s/lower 80s
Saturday, then lower/middle 80s Sunday under sunny skies and weak
ridging aloft. Overnight lows will show a similar trend, ranging in
the lower/middle 50s by Friday night, then gradually warming to the
lower-middle 60s by Sunday night.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR this evening will give way to MVFR cigs overnight as a warm
front lifts north. The specific timing of the onset of MVFR
remains in question, but short term guidance generally favors
05z at KSAV and 07z at KCHS. There could be a brief period of
transient IFR cigs at KCHS just before warm FROPA, but chances
look too low to justify a mention at this time. Will hint at IFR
with a TEMPO 09-12z with SCT007 BKN018. Isolated showers/tstms
will lurk about the KCHS terminal early Monday, mainly after
07z. VCSH will be mentioned between 07-13z to account for this.
Did not include any mention of TSRA at this time. Cigs will lift
to VFR by 13z at KCHS and 10z at KSAV as the warm front moves
north of the terminals. Gusty winds will develop by early
afternoon as a sea breeze moves inland. Gusts as high as 20 kt
can be expected.
Extended Aviation Outlook: VFR conditions should prevail at both CHS
and SAV terminals through Tuesday. Flight restrictions are possible
at both terminals Wednesday into Thursday with showers/thunderstorms
occurring near/along a passing cold front.
&&
.MARINE...
Tonight: Southeast winds will veer more southerly as a weak warm
front lifts north. Speeds in the 10-15 knot range will prevail. Seas
will average 1-3 ft nearshore waters and 3-4 ft offshore waters.
Monday through Friday: Local waters will remain along the western
periphery of high pressure extending across the western Atlantic
early week, well in advance of a low pressure system and associated
cold front approaching the coast mid week. South-southwest winds
should gradually increase early week, surging upwards to 15-20 kt at
times daily. Seas should also build up to 3-5 ft into early
Wednesday. A cold front should then shift offshore Wednesday night
into early Thursday with scattered to numerous showers and/or
thunderstorms. However, conditions outside thunderstorms should
remain below small craft advisory levels with winds turning more
west across local waters as high pressure builds across the area
heading into late week. There is some indication that a secondary
front could pass across local waters heading into Friday, which will
could usher in slightly stronger winds and higher seas Thursday
night and Friday. However, conditions should remain below small
craft advisory levels.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
1052 PM CDT Sun May 2 2021
...UPDATE TO AVIATION...
.SHORT TERM...(This afternoon through Monday night)
Issued at 1150 AM CDT Sun May 2 2021
Instability was beginning to build as of midday, with dewpoints
well into the 50s for most zones, and lower 60s across eastern
areas. NAM continues to project 2000-2500 J/kg CAPE east of the
dryline by late afternoon, as strong low pressure deepens near
Dalhart, Texas (987 mb on HRRR, 984 mb on NAM). Convection through 7
pm will be limited, but there will probably be some convection near
the southwest zones by evening, in the convergence zone northeast of
the strong surface low. In this drier air, some outflow winds are
possible from this activity, but coverage and impacts are expected
to be limited.
Much higher confidence of a strong thunderstorm complex
organizing over NE Colorado/NW Kansas by 7-8 pm this evening.
Various CAMs, HRRR and 12z NAM all agree impacts from this
MCS will be greatest along and especially north of K-96 this
evening. Given the linear nature of the upscale growth expected
along the surging cold front (and the impressive bowing on the
CAMs) severe/damaging wind gusts will be the primary threat this
evening. Wind gusts of 60-70 mph are probable, and coordinated
with SPC about upgrading severe wind probabilities (30%/enhanced).
Per SPC`s 1630z outlook, wind gusts of 70-80 mph are possible
from the organized bow echo along the I-70 corridor. Best guess is
the tail end of this line will track in proximity to US 50 this
evening, but isolated storms are possible south of US 50 as well.
Strong outflow from the complex will propel an already strong cold
front, surging it south through SW KS around midnight. Pressure
gradients immediately behind the MCS and north of the strong
surface cyclone in the Texas panhandle will be intense for a few
hours tonight, and will need to monitor for high wind/convective
wind products. Followed the stronger MAV guidance overnight, which
focuses the strongest winds/gusts along the preferred US 83
corridor. Increased pops to the definite category for the northern
zones tonight, and included damaging winds in the grids for areas
north of K-96.
A sharp change on tap for Monday in the post cold front
environment. Clouds and intense north winds will continue during
the daytime hours, and temperatures will consequently struggle.
12z NAM/GFS both cool 850 mb temperatures to near 4C at Dodge City
by late afternoon, keeping many locations in the lower to mid 50s.
MOS guidance continues to trend down, and followed that trend.
North 850 mb winds are sustained at about 40 mph all day long, so
gusts of that magnitude are expected. Finally, 12z NAM has come into
alignment with what ECMWF runs have been showing for days, with
widespread rain Monday afternoon. Increased pops to the 90% range
across the preferred southern and western zones, where rainfall
amounts near/over 0.50 inch look probable. Extended HRRR also shows
numerous rain showers blossoming Monday afternoon. CAPE appears to
be completely eliminated Monday, so took out any mention of thunder.
Rain will persist across primarily the southeast zones for much of
Monday night, as north winds gradually relax. Although clouds are
expected to hold in place through sunrise Tuesday, lowered minimum
temperatures to the upper 30s for many zones Tuesday morning.
.LONG TERM...(Tuesday through Sunday)
Issued at 210 PM CDT Sun May 2 2021
Quiet weather will prevail Tuesday through at least Friday, with
few if any impacts. Given this, and the complexity of the short
term, NBM guidance was generally accepted for the long term with
no modifications.
Much improved weather is expected Tuesday, as sunshine and much
lighter winds return. With light easterly boundary layer flow,
afternoon temperatures will still be about 10 degrees below
normal, in the 60s. Still a pleasant spring day, especially
compared to Monday.
A weak shortwave embedded in the NW flow aloft will zip through on
Wednesday. Moisture and instability will be limited, and model QPF
is also limited, so just accepted NBM`s minimal pops across the
northern zones for now. Rainfall will be limited.
Dry weather and a warming trend are expected Thursday and Friday,
as a midlevel ridge axis slowly expands eastward from the Great
Basin to the Rockies to the high plains. Strong south winds and
afternoon temperatures in the 80s will return by Friday as lee
troughing reorganizes.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1043 PM CDT Sun May 2 2021
Low level stratus is expected to develop along and behind a cold
front pushing southeast across western/central Kansas overnight,
resulting in primarily MVFR cigs developing in vicinity of all TAF
sites generally after 08-10Z. Brief periods of IFR cigs will also
be possible through daybreak. North winds 20 to 30kt with gusts
up to 35kt will develop west to east behind the aforementioned
cold front as it moves southeast into northern Oklahoma by daybreak.
Gusty winds may subside somewhat but are expected to persist through
Monday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 54 56 37 64 / 80 90 60 10
GCK 50 54 38 63 / 50 90 50 0
EHA 51 53 39 66 / 40 90 50 0
LBL 51 56 39 66 / 50 90 60 10
HYS 54 60 39 64 / 90 50 50 0
P28 58 64 46 66 / 30 50 70 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Grand Junction CO
856 PM MDT Sun May 2 2021
.UPDATE...
Issued at 854 PM MDT Sun May 2 2021
Winds have lessened with relative humidity beginning to recover.
Critical fire weather conditions are no longer being met so let
the Red Flag Warning expire at 8 pm MDT. Updated AFD to reflect
this update.
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 200 PM MDT Sun May 2 2021
Showers and thunderstorms continue over much of western Colorado
and northeast Utah this Sunday afternoon. Despite morning
convection, some clearing this afternoon has allowed an
environment with 500-700 J/kg of SB CAPE to develop. Per latest
RAP mesoanalysis, around 25-35 knots of bulk shear remain present
generally along and north of I-70. This will support a few
isolated thunderstorms throughout the remainder of the afternoon,
with the primary threat being wind gusts to around 50 mph given
a dry subcloud layer. Some small hail, generally 1/2 inch or less,
will also be possible. Farther south, the fire weather threat will
continue into the early evening hours. Clouds have developed over
the northern portion of the Red Flag highlighted zones, however RH
levels remain at or slightly exceeding criteria. No changes have
been made to the Red Flag warnings currently in effect.
From this evening through Monday night, attention turns to the
winter side of the storm system. Forecast guidance has continued
to trend upward with regard to snow totals over much of the
northern and central mountains of Colorado. This was most evident
in the NAM, as well as several short-term high-res models today.
As low pressure develops over southern Colorado early on Monday
morning, there is some hints of deeper moisture return westward
over the Continental Divide, supporting a period of moderate to
briefly heavy snow over the high country. Snow levels will remain
high, generally over 9,000 feet, however locally heavier snowfall
will help cool the column and locally lower the rain/snow line on
Monday morning. While some uncertainty remains in exactly where
the heaviest banded snowfall will occur, enough confidence exists
to issue winter highlights for this event on the western slope. A
Winter Weather Advisory has been issued for most all of the
central and northern mountains for elevations above 9,500 feet,
starting tonight and ending on Monday evening. 5 to as much as 10
inches of snow will be possible in the higher elevations. As
mentioned earlier, snow is possible below 9,000 feet as well, but
any accumulations will be limited to those areas that see the
heaviest snow rates. While road temperatures will be quite warm
given mild temperatures lately, some travel issues may develop
especially over the higher mountain passes on Monday.
Lower down in the valleys, liquid totals have also increased in
today`s forecast guidance. Places such as Grand Junction and
Montrose will likely see around 0.25" of liquid from now through
Monday. Around 0.1" is possible for Moab and Durango, with totals
coming in around 0.2 to 0.4" for Rifle, Aspen, Gunnison and Pagosa
Springs. Rain and snow showers are expected to taper off on
Monday afternoon and transition to a more convective, showery
event as low pressure pulls east into the high plains. Expect
below average temperatures through the period.
.LONG TERM...(Tuesday through Sunday)
Issued at 200 PM MDT Sun May 2 2021
We start out under west-northwest flow Tuesday as the current trough
continues east and a ridge builds over the western CONUS coast. On
Wednesday, the ridge axis moves over the Great Basin...sliding east
into our forecast area by Thursday afternoon thanks to a large mid-
level low spinning near the Pacific Northwest. As this occurs,
afternoon winds increase, temperatures rise, and humidities
fall...leading to increased fire weather concerns. However, as was
previously mentioned, green-up is well underway in most low / mid
elevations. Given the recent rainfall (and really the lower Pd
values), fuels readiness could likely be a limiting factor by that
point. That being said, given the forecast RHs (below 10%) and
wind gusts (exceeding 30-35 mph) on Friday and Saturday, marginal
fuel conditions will need to be watched closely. By the coming
weekend, this low settles just to the north of us, over Montana
for a day or two. As this occurs, models begin to diverge
significantly. At any rate, precipitation chances re-enter the
northern 1/2 of the forecast area on Saturday and Sunday as this
disturbance moves through to our north.
Temperatures start out near normals on Tuesday. With the ridge
headed this way, highs rise to around 10 degrees above normal
Thursday and Friday. As the ridge breaks down and the mid-level low
moves just to our north, temperatures return near to just below
normals for to round out the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 547 PM MDT Sun May 2 2021
Showers and thunderstorms continue to grow in coverage late this
afternoon with a continued threat of gusty outflow winds and
possibly small hail and brief moderate rainfall with the strongest
storms. VFR will remain the dominant forecast but temporary ILS
to MVFR could be possible if a storm moves directly over an
airfield. KDRO...KTEX...KCNY will be the least probable to see
this activity through the evening hours. Activity will transition
to widespread lighter precipitation overnight bringing ILS to
MVFR conditions to many areas by sunrise on Monday and continuing
through the afternoon hours. A mix and changeover to snow is
possible at higher mountain TAF sites by Monday morning.
&&
.FIRE WEATHER...
Issued at 854 PM MDT Sun May 2 2021
The main part of this storm system will stall over
western Colorado overnight bringing a better coverage of
precipitation to the area...including high elevation snow. This
will bring a reprieve to fire weather conditions until Friday
when the next possible critical fire weather day is coming.
Critical fire weather conditions look to return Friday into
Saturday with dry and breezy conditions and a return to above
normal temperatures.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 6 PM MDT Monday for COZ004-009-010-
012-013-018.
UT...None.
&&
$$
UPDATE...MDA
SHORT TERM...MAC
LONG TERM...SS
AVIATION...MPM
FIRE WEATHER...TGJT
Area Forecast Discussion
National Weather Service Grand Rapids MI
955 PM EDT Sun May 2 2021
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 328 PM EDT Sun May 2 2021
- Storms north tonight but quiet south
- Rain moves into southern 1/3rd mostly dry elsewhere
- Convection across all Southwest Michigan Monday night
- Trailing storm misses this area Wednesday
- Yet another cold front Friday with showers
&&
.UPDATE...
Issued at 955 PM EDT Sun May 2 2021
Downdraft capes are around 800 J/KG in a corridor from MKG and
Holland across GRR to Alma per latest SPC mesoanalysis. Also some
fairly strong winds of 40-45 kts are noted in RAP progs at 2000
ft or so, related to the low level jet in the area. Thus any
showers or storms that develop over the next few hours south of
the current convection could produce localized wind gusts over 40
mph.
Lakeshore communities south of Whitehall may see some gusts over
40 mph the next few hours even without convection nearby as the
core of the low level jet is over srn Lk MI.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 328 PM EDT Sun May 2 2021
- Storms north tonight but quiet south -
We are expecting showers and thunderstorms to become numerous over
the northern third of our forecast area tonight (8 pm ish). The
remainder of southwest Michigan will be unseasonably mild but
quiet weather-wise.
We have that southern stream closed upper low that is being booted
northeast as a stronger Pacific system digs into the Southwest
CONUS tonight. As that comes out toward the southern Great Lakes
tonight the ridge axis ahead of the system will move east of the
area. That will start to feed deeper moisture into this area.
Meanwhile the jet entrance region of jet segement on the polar jet
will be tracking across Lake Superior tonight. These two features
(southern stream system and northern stream system) will activate
the warm front (which was a stationary front today). The greatest
instability will be over western sections. Still the thunder risk
is marginal at best. The low levels will be rather moist so we
will not have the downdraft cape like last night. The precipitation
will be more of rain showers than thunderstorms. The heaviest
rainfall will be north of Route 10.
The rest of the county warning area will be partly cloudy with
lows in the 60s.
- Rain moves into southern 1/3rd mostly dry elsewhere -
On Monday we have that system from the Southwest CONUS tracking
mostly just south of this area. We will get the northern edge of
the rain shield of the system. There is little if any instability
for this part of the system. It will just be light rain and that
will mostly if not entirely be south of I-96. The I-69 area will
see the greatest rainfall from that system. Even there expect less
than a quarter inch of precipitation.
The warm front will have lifted far enough north on Monday so I do
not believe we will see much convection in that area during the
day.
- Convection across all Southwest Michigan Monday night -
Monday night we get the jet entrance region lift of the northern
stream system to act on the deeper moisture transported north by
the southern stream system. I would think the entire area should
see SOME rain (at least .10 inch or so). This will not be an all
night rain, but an area of convection ahead of the cold front. The
showers may last about 3 hours in any one place. There is between
500 and 1000 j/kg of MU cape over western sections just ahead of
the cold front so there will be some thunderstorms. Sounds from
the models look moist to over 500 mb ahead of the cold front so
not a lot of potential for strong downdrafts. It should be noted
over the eastern CWA, the cape does not get much over 500 j/kg,
so the risk for thunderstorms is less over eastern sections. Even
so all areas should see some rain Monday night.
- Trailing storm misses this area Wednesday -
The northern stream polar jet core will stay north of this area
until the end of this week. That will keep the really cold air
away until then. Meanwhile the Pacific system that booted the
system out of the Southwest CONUS to give southern sections rain
Monday will pass south of here on Wednesday. The core of the jet
segment with that system does not get north of I-80 so the rain
will likely not get to much farther north than that. Once again
the I-69 area is the most likely to see some light rain from that
event.
- Yet another cold front Friday with showers -
Just so you know it is spring in Michigan, we get a much stronger
push of cold air for Friday into the weekend. This is the result
of a northern stream closed upper low digging farther south that
it typically would at this time of year. That happens due to a
large blocking upper high over Greenland and a strongly developing
Pacific storm off the west coast. That Pacific system really
builds a large upper ridge over the western CONUS. The combination
of the northern stream upper low being so far south and Pacific
system building such a large upstream ridge will lock us in the
cold air for a few days. There should be enough moisture around
for most areas to see showers later Thursday into Friday from this
event.
I would expect frost and freezing temperatures Friday night once
the cold air is established and there is some clearing of the
clouds.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 758 PM EDT Sun May 2 2021
Conditions remaining VFR until very late tonight when MVFR cigs
should become more prevalent. IFR cigs are quite possible from
12Z-18Z Monday, with a higher chance of that at AZO/BTL/JXN than
at MKG/GRR/LAN.
Scattered rain showers are expected late tonight into Monday
morning. Occasional vsbys reductions of 4-5 miles may occur,
mainly at AZO/BTL/JXN. The main thunder risk this evening should
stay north of the srn Lwr MI terminals.
Gusty south sfc winds to 25 kts this evening will relax to around
10 kts overnight into Monday.
&&
.MARINE...
Issued at 935 PM EDT Sun May 2 2021
Southerly low level jet has been strengthening this evening and
will continue to do so for the next few hours before gradually
diminishing late tonight. Have issued a small craft advisory
south of Whitehall until 5 am for south winds to 30 kts.
With the cold air coming back Tuesday we will more than likely
need a small craft advisory again.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 5 AM EDT Monday for LMZ844>847.
&&
$$
UPDATE...Meade
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Meade
MARINE...Meade
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1045 PM EDT Sun May 2 2021
.SYNOPSIS...
A weather disturbance will move northeast from Louisiana crossing
our region tonight and Monday with showers and thunderstorms. Our
weather will remain unsettled until a cold front crosses from the
west on Wednesday. We may dry out temporarily on Thursday as high
pressure moves past to our north. Expect some rain on Friday mainly
over the mountains.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1045 pm: Still relatively quiet across the area with only
isolated low topped convection across the Upper Savannah
Valley. The latest model guidance has trended downward in shower
and thunderstorm coverage and intensity overnight likely owing
to a lack of a kicker and a nocturnal cap and therefore keeping
instability mostly elevated. However, because of the capping
overnight, it now looks like daytime heating could provide a
rather robust convective response with the latest HRRR in
particular covering much of the area. The increased coverage may
limit severe potential somewhat, but potential increase the
hydro threat. Still expecting enough moisture combined with
increasing orographic enhancement for likely PoPs by late
tonight over the mountains with chance or less elsewhere. Bumped
PoPs up considerably for the mid morning to mid afternoon
period Monday due the expected blossoming of convection.
Otherwise, in response to the next round of height falls
overspreading the Desert Southwest, the upper low over the south
central Conus will pick up speed and evolve into an open wave and
dampen as it lifts from the TN Valley to the Mid-Atlantic late
tonight into tomorrow. Increasingly moist warm advection
overspreading the forecast area will result in increasing pops
beginning this evening, with likely to categorical pops expected to
encompass all but the southeast quarter or so of the forecast area
by daybreak Monday. CAPE will be adequate to support scattered
thunderstorms over much of the area. Short term guidance is quite
disparate regarding the degree of surface-based instability
overnight, with the NAM depicting values of around 500 J/kg, and the
GFS offering little more than 0. If any appreciable instability is
realized, deep layer shear of up to 40 kts will yield a small severe
storm threat tonight.
Pops maximize across the forecast area between 10 am and 3 pm
Monday, with most locations receiving at least a likely pop. Mid-
levels will dry during the afternoon, as dampening wave passes north
of the forecast area, but low level will remain juiced, with
dewpoints likely pushing well into the 60s. As such, guidance
depicts moderate levels of PM instability along with still-adequate
shear. The limiting factor for afternoon convection will be an
absence of organized lift, possibly even weak DNVA in the wake of
the wave, and this will limit coverage of convection after 3 pm or
so. Nevertheless, if anything can initiate, the environment will
support a continued marginal threat of severe storms through the end
of the period. Min temps tonight will be well above climo, while
afternoon thinning clouds should allow maxes to warm to near normal
in most areas.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 130 PM EDT Sunday...The short range period remains active as
waves of ulvl energy traverse the flow Tue night. With continued
upslope/isent lift across the wrn zones...isol convec will likely
continue overnight while tapping into elCAPE on the order of 1000
J/kg. The FA remains in the warm sector Tue ahead of a cold front
impinging upon the NC mtns and along with good sw/ly flow, max temps
shud reach 10-12 degrees abv normal while sfc td/s are maintained in
the l60s. Soundings on the NAM and GFS show sbCAPE developing in the
low-moderate range while bulk shear lowers a little from Mon`s
values into the 25-30 kt range. Still, there should be enough
cape/shear interaction to expect multi-cells, with a few becoming
quite stg or severe. The afternoon period aft 18z may be interesting
as cross sections on the GFS/NAM both indicate a pronounced blob of
negative omega east of the mtns while the h92-h85 flow sets up a
fairly strong w/ly downslope component. This flow could disrupt
convec activity in the immediate lee and make for better chances of
tstms across the ern and srn zones. The cold front arrives to the NC
mtns Tue night and the models have varying timings with it`s
passage, but generally it looks like the llvl convg zone and tstm
potential will shift east of the FA before 18z. Yet, there is a
smaller possibility accordng to the NAM, the front will slow and
linger south the I-85 corridor into the later afternoon. Shear
levels will remain low-end and depending on when exactly the front
crosses the FA will determine the amt of destabilization available
for stronger tstm development. For now, expect mainly general tstms
or a poorly defined squall line before 18z.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 150 PM EDT Sunday...the 500mb flow remains active in the
second half of the week with a trough setting up for the East in the
weekend. Brief dry high pressure passes to our north Thursday
morning as the next shortwave crosses Missouri. A broad trough
deepens Thursday night with its axis nearing the Appalachian chain.
The latest GFS has rain crossing the mountains through the central
Carolinas late Thursday night. The ECMWF has the bulk of the rain
passing over VA and NC late Friday. The coolest night will be Friday
night with some upper 30s in the NC northern mountains. Some NW
Flow showers along the TN border Friday night but otherwise dry
weather into Saturday with the next shortwave approaching from
Arkansas. The bulk of the rain associated with this system begins to
arrive over our western zones late Sunday night. Temperatures will
be below normal Thursday through Saturday then nearing normal on
Sunday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Moderate confidence in cigs/vsbys with low
confidence in shra/tsra timing. TSRA could be possible as early as
04Z for SC terminals and after 06Z elsewhere, although guidance
suggests peak chances sometime in the 10Z to 18Z window for most as
covered by prob30. TSRA is possible after this window, but guidance
suggests coverage will be widely scattered at best. If cigs scatter
out in the afternoon, there may be some potential for brief wind
gusts in the 25-30kt range. Brief wind gusts from 260 will be
possible at KAVL between 15Z and 19Z.
Outlook: A cold front will likely bring another round of SHRA/TSRA
to the area by Tue afternoon, with chances persisting into Wed.
Another lull in convection is expected for the end of the week.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 91% High 86% High 100%
KGSP High 93% Med 68% Med 75% High 92%
KAVL High 86% Med 65% High 80% High 100%
KHKY High 100% Med 60% Med 79% High 96%
KGMU High 94% Med 70% Med 68% High 84%
KAND High 91% Med 77% Med 72% High 94%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...JDL/Munroe
SHORT TERM...SBK
LONG TERM...DEO
AVIATION...Munroe
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
912 PM CDT Sun May 2 2021
.UPDATE...
912 PM CDT
Minor tweaks to the going forecast for the rest of tonight, with
the message remaining showers mainly overnight for areas
along/east of I-55, and a chance for a few showers or a storm to
sneak into far northern Illinois. The severe threat is low if
that were to happen. Confidence has further increased in
convection, some probably on the stronger to possibly severe end
with gusty winds, moving into northern Illinois mid to late
afternoon Monday.
First for the rest of tonight, the system responsible for the
rain in the southeast CWA -- an upper low over eastern Arkansas --
has its broad upper diffluence creeping northward across the
southern halves of Illinois and Indiana. Light showers in that
area will continue to slowly expand north, favored to reach
southern parts of the Chicago metro after 2 A.M. This rain should
primarily be light, lingering for a few hours after sunrise before
departing.
To the north, convection lit up along the frontal zone from
northern Iowa into central Wisconsin. Convective prorogation
will continue to favor more of an eastward movement, especially
with the offsetting strength of the southerly low-level winds.
However, there are multiple southward-moving outflows seen on
radar, satellite, and surface obs in southern Wisconsin, and
scattered convection on this is probable at least for the next few
hours. This should result in the outflow getting close to the
state line after midnight. While MUCAPE tapers quickly with
southern extent (a stretched out 200 J/kg on the 00Z DVN
sounding), there is enough low-level moisture transport into these
outflows to possibly force a few showers or weak storms along/north
of I-90 late.
Looking ahead to Monday, the below AFD remains representative to
expectations and the potential for some severe storms. One key
thing we have been seeing with incoming observational data and CAM
solutions is the likely presence of an MCV currently along the
Nebraska/Kansas border that several high-res solutions pick up on
and track into/across northern Illinois Monday mid-afternoon into
mid-evening. With little in the way of convection expected to our
south (upstream in the low-levels) through peak heating Monday,
this more convectively-enhanced wave than it previously looked
should have a decent air mass to work with. A convective uptick is
favored during peak heating in eastern Iowa to north central
Illinois mid to late afternoon. While morning clouds look like a
good bet, RAP soundings continue to support the afternoon cap
eroded with dew points peaking into the mid 60s up to I-80 and
possibly I-88. Mid 60s dew points are presently up to the
Missouri/Arkansas border, so that`s definitely doable.
The overnight shift will assess convective evolution further, and
try to lock down timing that still has 3 to 4 hour differences in
various NWP solutions.
MTF
&&
.SHORT TERM...
242 PM CDT
Through Monday night...
Another day of breezy and warm conditions here, with temperatures
early this afternoon generally in the low to mid 80s north of an
encroaching region of higher cloud cover. Regional visible
satellite loops show a bit more in the way of lumpy cumulus
development ongoing north of I-88 where surface dewpoints are in
the upper 50s with gradually eroding convective inhibition.
Currently, things are still quite capped to surface-based parcels
with a lingering pocket of +8 to +9 C air around 750 mb per recent
AMDAR soundings. With surface temperatures rising into the mid
80s, it`s possible we erode enough of the lingering MLCIN before
sunset to pop a few showers--maybe a thunderstorm--north of I-88.
Any activity that does develop shouldn`t be too long for this
world with the loss of daytime heating, but 30 degree dewpoint
depressions, 0-3 km lapse rates approaching 9 C/km, and DCAPE
values near 900 J/kg could support some gustier winds should any
deeper showers/storms manage to develop.
Additional--more organized/vigorous--convection is expected to
develop farther to our north and west through this afternoon and
evening ahead of a quasistationary front which stretches across
central Wisconsin and back into southern Minnesota. This activity
will build south and eastward with time, but is expected to wane
with time. It`s possible some of this activity (in a very weakened
state) presses into northwest Illinois later this evening, and
have left some low-grade PoPs in place there to capture this
potential. To the south, light showers associated with the
divergent upper-level flow ahead of a strung-out shortwave will
push into our forecast area, with the most likely areas to receive
some light precipitation those that are south and east of I-55.
This activity will peel east of the area through the mid-morning
hours on Monday, leaving behind generally dry conditions over the
region but with plenty of low and mid-level cloud cover which will
stunt our temperature climb and also the destabilization process.
However, model guidance is in pretty good agreement driving low
to even mid 60 degree dewpoints into north-central Illinois
through the afternoon hours ahead of a pretty vigorous shortwave.
There remains some degree of disparity regarding the location of
the northern terminus of the advancing EML plume tomorrow, but if
anything, guidance has trended a bit farther north into the CWA
with this. What this means for us is a greater degree of capping
through the morning/early-mid afternoon hours, but a somewhat
greater supply of instability ahead of the aforementioned
shortwave, especially as you work farther south of I-80 and into
central Illinois.
Deep layer shear will remain in short supply through much of the
morning hours on Monday, but looks to increase rapidly with the
approach of the aforementioned shortwave through the late-
afternoon. As a result, a gradual intensification of convection
along an incoming cold front is possible as it approaches our
region from the west. Thunderstorms appear likely with this
feature as it traverses our forecast area, and some could become
severe should MLCAPE values indeed claw their way towards 1000-1500
J/kg as some guidance suggests into an increasingly-sheared
environment. Largely boundary-orthogonal shear may help keep some
degree of discrete-ness going with a gradual clustering of cells
with time yielding a damaging wind threat given the fairly fast H7
flow and some degree of mid-level drying with time. The steepened
mid-level lapse rates may also afford storms the potential to
produce some large hail, and, as with any system sporting a
sub-1000 mb surface reflection traversing eastern Iowa, the
tornado potential will be non-zero. Do think the tornado potential
is probably on the lower side at this time given the
sufficiently-veered look to our surface winds and overall pretty
small hodographs in the 0-3 km layer, but still something to keep
an eye on. The main window of concern is a later one with
everything mentioned, closer to 5-9 PM or so. The main threat axis
may align mainly south of I-80 (into the corridor of better
instability), but will extent across the entire area and may
increase north towards the I-88/I-90 corridors if instability
increases sufficiently. Activity will clear the area through late
Monday evening.
Carlaw
&&
.LONG TERM...
217 PM CDT
Tuesday through Sunday...
A cooler stretch of weather is expected to starting Tuesday with
generally dry conditions expected outside of a couple systems
that may bring precip chances. On Tuesday, a cold frontal
boundary will be positioned across central IL with the low/mid
level baroclinic zone still across the local area. A longwave
trough will move across the area into Tuesday evening while a
surface low tracks up the Ohio Valley ahead of a more amplified
portion of the upper trough. As a result, Tuesday appears to be a
showery day, especially across the southern part of the area
closer to the front and better larger scale forcing. It will be
cooler with highs in the mid to upper 50s north to around 60
south, with winds off Lake Michigan keeping lakeshore areas in the
lower 50s.
High pressure moves across Wednesday leaving dry conditions and highs
in the lower 60s for all but lakeshore areas. Light winds will
likely support lake breeze development so afternoon temps will
likely only be in the low to mid 50s lakeside. By this time, large
scale ridging will have developed across western North America
with a broad upper trough over the eastern half. A shortwave
trough is expected to traverse the flow and cross the area
Thursday bringing chance for showers and maybe a few
thunderstorms. The wind field should remain light enough to
support another lake breeze. High temps should range from the
upper 50s north to lower 60s south, with mid 50s near the lake.
The pattern begins to shift east Friday allowing for somewhat
milder air to return, except for areas near the lake once again.
While the upper flow temporarily flattens into Saturday another
trough is expected to pivot southward toward the region with a
second trough ejecting from the southwest triggering surface low
pressure which will move east or northeastward across the Ohio
Valley. This would support another chance for
showers/thunderstorms some time Saturday into Sunday.
MDB
&&
.AVIATION...
For the 00Z TAFs...
636 PM...Primary forecast concerns include...
Scattered thunderstorms Monday afternoon/Monday evening.
Ifr cigs Monday morning.
Gusty southwest winds tonight.
Chance of showers early Monday morning.
Southwest winds will remain gusty this evening, into the mid 20 kt
range and will slowly diminish after midnight. Winds will turn
more southerly early Monday morning and may briefly drift to the
south/southeast after sunrise, but will turn back to the southwest
in the 10-12kt range by late Monday morning.
An area of rain across central IL and central IN will slowly drift
to the northeast later tonight and a period of showers is possible
during the predawn hours. Confidence is low for how widespread
this activity will become as well as its duration and its possible
that the bulk of this shower activity will remain east of the
Chicago area terminals with a few lingering showers possible
through mid morning Monday.
A large area of mvfr cigs will spread north across the area early
Monday morning and there is good agreement that these will lower
to ifr around or just after daybreak for a few hours before then
lifting back through mvfr by late morning and then a low vfr deck
by early afternoon. Though its possible high mvfr cigs may remain
prevailing across northwest IL and at rfd in the afternoon.
Scattered thunderstorms are expected to develop across eastern IA
and northwest IL Monday afternoon and quickly move east across the
terminals through early evening. Models have been handling this
system and these convective trends well for several days. Still
some uncertainty on timing, but current tempo timing covers the
expected time period well, with some timing adjustments possible
as trends emerge. Left thunder mention out of the gyy taf for now,
as best current timing could be at or just after the end of this
forecast. Expect some weakening of this activity as it spreads
east into the Chicago area and for now have only included higher
wind speeds/gusts in the rfd tempo but these may be needed at the
rest of the terminals as winds will likely shift from the
prevailing southwest to a northwest direction as the storms move
through. Prevailing winds expected to remain north/northwest after
this activity shifts to the east. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...nearshore waters
until 3 AM Monday.
&&
$$
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Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
609 PM CDT Sun May 2 2021
.DISCUSSION...
Updated to include the 00Z aviation discussion below...
&&
.AVIATION...
An upper level storm system is rotating over AR early this
evening...with isolated to scattered SHRA ongoing across parts of
the area. Most widespread precip is ongoing across the NRN
terminals now. Further south...a break was seen...but additional
SHRA/TSRA will be possible this evening before this system exits
to the east later tonight. While precip will limited
overnight...low CIGs will be seen through after sunrise Mon
morning. Some improvements in flight conditions will be seen by
the afternoon hrs...though a new storm system will approach from
the NW by Mon evening. This system will bring another round of
SHRA/TSRA...especially beyond this TAF period Mon night.
&&
.PREV DISCUSSION...(ISSUED 257 PM CDT Sun May 2 2021)
SHORT TERM...Tonight Through Tuesday Night
TODAY AND TONIGHT...
Recent MSAS data and mosaic radar imgry depicted a large swath of
rainfall moving across Srn AR w/ modest cyclonic low-lvl flow
beginning to advance N/wrd. Vis sat imgry depicted some clearing
over S/Wrn AR and an expansive status/cirrus deck over much of the
state. Over N/Ern TX and Nrn LA, a diurnal Cu field was noted, w/
some developing updrafts in LA.
Through this afternoon and evening, this clearing trend may continue
to expand over portions of Srn and S/Ern AR, however destabilization
wl be limited should any clearing occur. As such, this wl hinder
widespread thunderstorm activity Sun night. 12Z and 18Z CAM guidance
cont to depict a small swath of ML buoyancy of 500-1000 J/kg w/
minimal CINH over much of S/Ern AR. Should any thunderstorm activity
develop, it wl lkly be limited to far Srn and S/Ern AR and bordering
over the MS river into Nrn MS. This trend has also been captured by
the recent CAM guidance, so while sig svr wx in the FA is becoming
more conditional and unlkly, it is still non-zero. Given discrete
storm development, some large hail would be the primary threat.
MON AND TUE...
Through Mon and Tues, more unsettled wx wl persist w/ some
potential for svr wx Mon night into Tues morning...Overall, longer
range deterministic guidance continues to prog a significant
warming trend for the ARKLATEX region on Mon. Deepening sfc low
pressure over the Red River valley wl support a strengthening sfc
pres grad and increasing Srly sfc flow magnitude. A poleward
moisture flux wl cont over the region w/ fcst Td`s in the upper
60s over much of the FA by Mon evening. Strong WAA wl also support
the potential for the warmest day of the year in the Natural
State thus far w/ readings in the mid to upper 80s across Cntrl
and Nrn AR, and even some areas seeing T`s in the 90s across the
S. Overall, a hot, muggy, and windy day wl be seen for most w/
Srly winds of 10-15 kts and gusts in excess of 20 kts, especially
over the Delta region and Ern AR.
Variability among mesoscale and global deterministic guidance has
been a fight through the fcst for Mon night, w/ global model solns
remaining more aggressive among QPF and sfc mass field progs, while
NAM guidance remains somber and rather mute as far convective
activity. Mon night, a sfc trof of low pressure and weakly organized
cyclonic flow wl extend from N/E TX through the N/Wrn portion of AR
and into the Upper Midwest. A cold frnt wl be positioned along this
axis and wl lkly serve as the forcing mechanism for potential sig wx
through the overnight PD.
Through the midnight hours, the frnt wl come into phase w/ a low
amplitude perturbation moving through mean S/Wrly H500 flow over the
region. Despite initializing PoPs/QPF w/in a nocturnal timeframe b/w
06-09Z, diurnal cooling remains meager in diminishing substantial ML
buoyancy, w/ progs in excess of 2000-2500 J/kg along the bndry near
the time of CI, w/ minor CINH in place from an apparent elevated
inversion per pt fcst soundings.
As of this fcst, it seems the primary area of focus is shifting
N/wrd as outlined by the SPC D2 SLGT risk area, while over Srn AR,
the primary forcing for ascent wl be too lagged and diurnal
cooling/CINH development wl hinder nocturnal thunderstorm
development. GFS sfc mass fields continue to depict a nocturnal
precip/thunderstorm complex developing along the bndry/buoyancy axis
and advancing E/wrd through the late night hrs, and synoptic hr HRRR
runs have begun to capture CI as well along the cold frnt as it
enters N/E OK and N/W AR where some damaging hail could be possible
early on among semi-discrete storm clusters. However as
consolidation and organization begins, damaging winds wl become the
primary svr hazard as storm mode becomes more linear.
Tues, the aforementioned cold frnt wl sag S/Ewrd across the state w/
N/Wrly winds beginning to filter in drier air over the FA by the
later afternoon and evening. PoPs wl remain over much of the region
through the day w/ the FROPA and primary upper impulse lifting
N/Ewrd, however most can expect RH values and the general mugginess
begin to subside from N/W to S/E through the later evening, as Cntrl
Plains high pressure begins to sag S/wrd.
LONG TERM...Wednesday Through Sunday
A storm system/cold front will be exiting to the east to begin the
extended period. A large area of high pressure will follow the
front, and that will bring several days of dry conditions and below
average temperatures.
Toward the end of the week, the high will depart, and return flow
will bring temperatures back up to seasonal levels by the weekend.
At the same time, a new storm system in the central Plains will drag
a cold front toward Arkansas, and rain chances will increase.
Scattered showers/isolated thunderstorms are in the forecast
Saturday and Sunday. At this time, the dynamics aloft to support
severe weather do not look impressive, but we are a week away.
It is too soon to say for sure what will happen.
&&
.LZK Watches/Warnings/Advisories...NONE.
&&
$$
Aviation...62
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
651 PM CDT Sun May 2 2021
.SHORT TERM...(This evening through Monday night)
Issued at 231 PM CDT Sun May 2 2021
Scattered showers continue this afternoon from southwest MN to
northwest WI. A nearly stationary boundary from northwest IA to the
vicinity of Albert Lea and Rochester will be the focus for additional
activity this evening. Some instability has built up across IA this
afternoon and slightly better convergence along the front should help
focus convective activity. The thunderstorms will slowly sag
southeast with the front through the evening. Very little will remain
until the surface low advances northeast across IA Monday, at which
point post frontal showers will develop. How far northwest they can
reach is the main question. Some hi-res models bring them up into the
metro, similar to the 12Z NAM, but GFS, Canadian, ECMWF keep them
confined more to southeast MN. Introduced some PoP farther north, but
kept it quite low for now until more certainty can be obtained.
.LONG TERM...(Tuesday through Sunday)
Issued at 231 PM CDT Sun May 2 2021
The long term will be fairly quiet with cooler temperatures.
An upper low over Manitoba/Ontario provinces will slowly move east
and deepen while ridging builds over the west. This will result in
cool northwest flow over the CWA which will lead to temperatures
that don`t really go anywhere. Each day will feature high
temperatures in the mid 50s to lower 60, and overnight lows in the
mid 30s to low 40s. A shortwave trough and associated surface low
will move from around the South Dakota/Nebraska border into Iowa
later Wednesday into Thursday, but guidance is a little further
south and west with this feature. It looks like an area of showers
will slide southeast through the CWA. A tenth or two of
precipitation looks possible, with heavier amounts along and south
of the Minnesota River Valley. Northern and eastern parts of the
forecast area may stay dry with this system.
Late in the week the guidance diverges. There is general agreement
in the guidance that the western ridge moves eastward and looks to
flatten as troughing moves into the west, but there are timing
differences. The Blend has slight to chance PoPs for us for next
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 651 PM CDT Sun May 2 2021
Instability gradient from Fairmont over to Winona and to the north of
Tomah in WI will move little tonight. This will keep TS activity
south of all MPX terminals. There has been a definite trend with the
HRRR/RAP with keeping bulk of activity tonight to the southeast, with
only EAU looking to have a good shot at seeing some light rain
tonight. Other issue this period is what will happen with cigs. Right
now, we are all VFR, but with widespread showers and storms near La
Crosse, expect MVFR/IFR stratus to develop there overnight that will
attempt to nudge back to the west tonight. The question is how far.
Tried to lean more toward the RAP for timing of these clouds, which
did delay things a little. In addition to these clouds, we will see
another band of stratus, possibly with a shower or two coming out of
the Dakotas with a secondary trough, this looks to bring some MVFR
cigs into AXN/STC. Monday looks cloudy, though toward the end of this
TAF period, we may start seeing some clearing out in western MN.
KMSP...We`ll see occasional light rain continue for a couple of more
hours, but with cigs remaining at or above 8k ft, this moisture will
continue to struggle to reach the ground. Still a good deal of
uncertainty with how far west MVFR/IFR stratus emanating from the La
Crosse area will make it, but there is potential MSP could stay
mainly VFR this period, with reduced cigs with the surface low to our
southeast remaining to the east of MSP, with lower cigs associated
with the western trough remaining north.
/OUTLOOK FOR KMSP/
TUE...VFR. Wind NW at 10-20 kts.
WED...VFR. Chc -SHRA/MVFR. Wind N 5-10 kts.
THU...VFR. Wind W 5-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
SHORT TERM...Borghoff
LONG TERM...CEO
AVIATION...MPG
Area Forecast Discussion
National Weather Service Pocatello ID
125 PM MDT Sun May 2 2021
.SHORT TERM...Tonight through Tuesday night. Early afternoon
satellite imagery was highlighting a short-wave disturbance shearing
SE across SRN Idaho as a shallow trough settled southward across the
Panhandle and NW Montana. There appeared to be two circulations
associated with the aforementioned short-wave...one over Mountain
Home rotating SE toward Wendover and the second shearing NE through
Rock Springs. The divergence aloft between these two systems was
helping to support thunderstorm activity along a line from Sun
Valley to Craters of the Moon to Springfield. There was little
agreement among the Hires models but the HRRR (which was handling
the current activity best) was showing intensification and coverage
across this area this afternoon and then quickly dying off after 7PM
MDT. Light shower activity is expected to linger overnight as the
shallow upper trough continues to shift SE across the NRN Rockies.
Lingering moisture coupled with increased solar heating Monday
afternoon should be enough to support scattered shower activity
across the ERN mountains. An incoming disturbance rotates over the
coastal ridge and dives SE into the NRN Rockies late Monday night
and Tuesday supporting the development of showers and afternoon
thunderstorms across the CNTRL and ERN mountains favoring the
Montana and Wyoming divide areas. Along with the passing
disturbance, we may see "near" Lake Wind Advisory conditions across
American Falls Reservoir through the day. Drier conditions follow
Tuesday night as the disturbance shifts east of the region and a
ridge of high pressure expands across the NW coast. Temperatures
will remain near normal through the period with a potential
Frost/Freeze event late Tuesday night into Wednesday morning. Huston
.LONG TERM...Wednesday through next Sunday. Ridge axis will shift to
the east on Thursday afternoon. Deterministic GFS and Canadian
models are spreading showers into the Central Mountains behind the
ridge. A deep upper trough will be in place off the Pacific Coast;
the showers Thursday afternoon will be from a fairly weak shortwave
lifting out of the trough. Models show the trough lifting across the
Great Basin Friday morning, while a closed low spins off the WA
coast. There is enough instability Friday for a slight chance of
thunder in the afternoon. There is good model consensus heading into
the weekend with the low progressing eastward across the Panhandle
Area by late Friday night. Ensemble clusters appear to show similar
solutions, but varying in the intensity of the low. Expect afternoon
convection to initiate once again on Saturday near the vicinity of
the low. The low should continue spinning in our area on Sunday, so
we`ll have a third consecutive day of thunderstorm mention.
Temperatures through the week will ramp up through Friday into the
80s, but cooler weather is in store for the weekend as the upper low
and associated surface cold front passes through. Hinsberger
&&
.AVIATION...A mid-level disturbance is enhancing showers over
southeast Idaho this afternoon. Radar at TAF issuance showed returns
from around Jerome to Pocatello moving south and some new developing
showers over the Central Mountains. Expect to see showers today and
tonight, though flight conditions should be predominantly VFR. Some
upstream trends indicate BYI may see a brief period of MVFR
conditions early this afternoon. A northerly wind is in place over
IDA and DIJ this afternoon, but southwesterly/westerly winds should
prevail at PIH and BYI today. We should see that northerly wind over
PIH late in the TAF period. Given the amount of moisture present,
there is a potential for morning fog/stratus, though latest NBM and
HREF runs favor VFR at all terminals. With light winds forecast at
PIH, have included VCFG mention for the early morning. Hinsberger
&&
.PIH WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Area Forecast Discussion
National Weather Service Tallahassee FL
833 PM EDT Sun May 2 2021
.UPDATE...
Increased pops north into southeast Alabama and towards the
Apalachicola River with showers and isolated thunderstorms
holding together and outperforming the high resolution guidance.
All other elements are on track. Updates sent.
&&
.PREV DISCUSSION [646 PM EDT]...
.NEAR TERM [Through Monday]...
Visible satellite imagery and animated radar imagery from KLIX
show an expansive area of showers and thunderstorms moving east of
the Mississippi River Delta heading to the NE. Linear
extrapolation of these storms shows a time of arrival into the
marine area around 22z and approaching Walton/Bay County just
before 00z. This progression has been handled well by successive
runs of the HRRR throughout the day, so see little reason to lower
PoPs in the forecast from the previous update. Instead, have
increased rain chances slightly in the 22z-06z time frame to
account for the progression of these storms. The storms will be
moving into a less thermodynamically favorable environment (it is
a little drier over the Fla Panhandle, plus loss of daytime
heating) and the deep layer forcing will be lifting out to the NE
with time, so do not expect the storms to persist much past 03z-
06z. Elsewhere, it should be relatively quiet through the evening
hours.
Overnight, as storms diminish, modest southerly flow of 4-8kt will
continue to advect in more moisture and this will result in
increasing low cloudiness prior to sunrise. The persistent wind
should limit fog development. These low clouds should last into
the late morning before starting to scatter.
By Monday afternoon, the airmass will be relatively unstable, with
model soundings suggesting SBCAPEs in excess of 1500-2000 J/kg.
All that is really missing is a substantive trigger. The 02/12z
Euro suggest this may be provided by a weak shortwave moving
through the southern stream flow. The 02/12z HRRR is also quite
active on Monday, so will show fairly high PoPs, especially
across the northern half of the forecast area.
Further examination of the model soundings suggest that storms
could be locally strong, but the threat for severe storms seems
low given the relatively weak deep layer flow.
.SHORT TERM [Monday Night Through Tuesday Night]...
Leftover storms from Monday should persist into the evening hours
until instability wanes before midnight. Another round of low
cloudiness is expected given the humid airmass in place.
By Tuesday, a cold front will start to approach the Mid South. A
similar thermodynamic environment will set up Tuesday afternoon
compared to Monday, with SBCAPEs in excess of 1500-2000 J/kg. The
only difference is in the kinematic fields which are a little
stronger on Tuesday afternoon, likely due to an approaching
shortwave trough. As a result, the severe threat is marginally
higher across the region, with the most likely threat being
damaging winds. This threat is greatest across the western half of
the region, particularly into Southeast Alabama.
By Tuesday night, the cold front moves closer to the region, with
showers and storms likely to continue through the overnight hours.
continued humid conditions will support overnight lows in the
lower 70s.
.LONG TERM [Wednesday Through Sunday]...
The long term period begins with a cold front entering the
forecast area and serving as focus for showers and thunderstorms
developing across the region throughout the day on Wednesday. The
associated shortwave is predicted to dampen out considerably
across the Tennessee River Valley, which weakens the kinematic
fields to where the severe threat looks rather low.
Model differences emerge Wednesday night into Thursday on whether
the front will be fairly progressive (Euro) or stall and wait on a
trailing shortwave in the northern stream (GFS) to kick the front
out of here by Friday. Given that cold fronts this time of year
tend to be slow movers through the Deep South, will lean the
forecast toward the GFS, which suggests holding onto PoPs at least
into Thursday afternoon.
Thereafter, the models are in much better agreement about dry and
tranquil conditions persisting through the remainder of the
period. Temperatures in the afternoon will only be in the upper
70s to near 80 with dewpoints in the upper 40s to lower 50s, which
will create a comfortable weekend.
.AVIATION...
[Through 00Z Tuesday]
Line of showers and storms are tracking off the northern Gulf
coast moving eastward. There is a possibility that the line could
make it to ECP in the next few hours and have added a tempo group.
Otherwise, expect a period of IFR cigs overnight giving way to
gusty southwest winds Monday of AOA 20 knots.
.MARINE...
Southerly winds will increase on Monday ahead of the next storm
system and could approach cautionary levels at times over the
western waters. Storms over the marine area will increase Tuesday
into Thursday creating locally higher winds and seas. As a cold
front comes through on Thursday afternoon, winds will shift to
offshore, remaining below headline criteria into the weekend.
.FIRE WEATHER...
A humid airmass will remain in place across the region through the
next few days. As southerly flow increases, transport winds and
dispersion indicies will increase through Tuesday. Scattered showers
and thunderstorms will also be possible through at least Thursday
as a cold front moves into the region. This front will clear the
area by Friday, with a drier and marginally cooler airmass arriving
for the weekend. Even with this drier air moving in, red flag
conditions are not anticipated for the next several days.
.HYDROLOGY...
Only one river forecast point, the Withlacoochee River near
Quitman (US-84) remains in minor flood stage, but not for much
longer. This location should drop out of flood stage by this
evening. While increased flows down the Withlacoochee and into the
mainstem Suwannee will continue through the remainder of the week,
no forecast point in the Suwannee system is expected to reach
flood stage.
Rainfall this week doesn`t appear at this point to be especially
heavy, at least over a widespread area. That being said, there are
sporadic signals in various models that locally heavy rainfall
could be possible on Monday evening through Tuesday and then again
on Wednesday and Thursday. But given the uncertainty, it is
difficult to pinpoint specific flood threat areas. Certainly, this
time of year, the flood threat tends to transition more to flash
flood concerns as area rivers tend to require more rainfall to
generate significant responses.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 85 71 86 71 / 10 30 10 20 30
Panama City 71 81 72 81 71 / 50 40 10 30 40
Dothan 70 84 71 85 69 / 50 70 30 40 50
Albany 70 87 71 87 70 / 20 70 30 40 40
Valdosta 68 87 70 88 70 / 10 20 20 20 30
Cross City 69 87 70 87 71 / 10 10 10 10 20
Apalachicola 72 80 72 80 71 / 20 20 10 20 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...Scholl
NEAR TERM...Godsey
SHORT TERM...Godsey
LONG TERM...Godsey
AVIATION...Scholl
MARINE...Godsey
FIRE WEATHER...Godsey
HYDROLOGY...Godsey
my last regularly scheduled forecast discussion before I move on
in my career to WFO La Crosse. It has been a privilege
forecasting for the fine folks of northeastern Kansas and I look
forward to new forecasting challenges back home in the Upper
Midwest.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 659 PM CDT Sun May 2 2021
Not a significant change in the 00Z forecast. Tracking convection
over western Kansas. Depending on the evolution, much of this is
expected to pass the terminals off to the southwest. However, this
is some chance for a few stronger winds to make their way through
the terminals associated with decaying convection. Expecting the
timing on this would be aftern midnight. Any precipitation is
likely to be in the form of showers rather than thunderstorms at
this time. The front pushes through the area and winds turn to the
northwest behind this initial outflow and fully turn to the
northwest shortly after sunrise into mid morning. Any IFR
conditions may be brief and likely around the sunrise time frame
but could remain north of the terminals due to a more mixed
airmass in place over the terminals.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Skow
AVIATION...Drake
Area Forecast Discussion
National Weather Service Las Vegas NV
255 PM PDT Sun May 2 2021
.SYNOPSIS...Isolated showers over Lincoln and northern Mohave
Counties will dissipate early this evening. Monday will be the
coolest day of the work week before temperatures resume their upward
trend through Thursday. Another system enters the Pacific Northwest
late in the week bringing a return of gusty winds and cooler
temperatures.
&&
.SHORT TERM...through Monday night.
So far, isolated showers and thunderstorms in Lincoln County
generally running along a line from Beaver Dam State Park northward
toward Great Basin National Park. Latest HRRR indicates best
convective initiation will continue across southwest Utah with any
additional storms for Lincoln County hugging the state line through
the rest of the afternoon. Still can not rule out a stray shower
reaching as far south as near Mesquite and the Arizona Strip into
early evening.
Once showers wrap up this evening skies will become clear overnight
while north breezes linger. North winds of Monday will be strongest
down the lower Colorado River between Lake Mohave and Lake Havasu
City. Temperatures will cool several more degrees from today with
highs topping out near early May normals.
.LONG TERM...Tuesday through Sunday.
Little has changed for mid-late week. Ridge axis progged to shift
east over the Great Basin through Thursday. Temperatures will spike
on Thursday, some 10-12 degrees above normal. Stronger south-
southwest wind gusts will again develop on Thursday ahead of an
approaching trough of low pressure. A bit more uncertainty regarding
eventual depth and timing with trough next weekend. Cooling
temperatures and continued gustiness a given. A slower/deeper
solution would promise a better chance for precipitation.
&&
.AVIATION...For McCarran...Gusty northerly winds remain in the wake
of this morning`s frontal passage. Gusts to 30 kt can be expected
through into the evening hours. After sundown, north to northwest
winds will continue but reduce to 10-15 kt with gusts to around 20
kt. Scattered clouds this afternoon will clear out this evening.
Another round of gusty winds can be expected Monday morning before
decreasing in the afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty Northerly winds will continue across much of the
area through the evening hours. Wind speeds of 20-30 kt are common
in the wake of the passing front. Expect lighter wind overnight with
an increase to 20-30 kt gusts during the morning hours. decreasing
clouds can be expected through the evening. Shower activity this
afternoon and evening is largely confined to northern and eastern
Lincoln County along the Utah border.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Pierce
AVIATION...Berc
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