Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/21/22
weather forecast discussion!
With the main cold front moving through the Panhandles this
morning, a much cooler airmass funneling south from the northern
Plains has made its presence in the region. High temperatures
today have been under performing compared to the latest numerical
data with some areas in the northern Panhandles not climbing out
of the 60s. As winds become more easterly and weaken this evening,
temperatures will drop into the upper 30s through mid 40s across
the Panhandles.
Observations in Colorado and Wyoming well upstream of the
Panhandles this afternoon have temperatures struggling to get out
of the 30s with snow being reported in some of these locations. A
piece of the core of the colder airmass will moderate as it moves
south into the Panhandles with a very notable H700 temp gradient
and a H850-700 (-)theta-e gradient reinforcing cold and more dense
airmass. This will result in increasing cloud coverage going into
the day tomorrow and with a persistent north to northeasterly
winds, temperatures may struggle to get out of the 50s in the OK
and northern TX Panhandle with 60s in the southern TX Panhandle.
Tomorrow night, some frost headlines may be needed. As we approach
sunrise very early Sunday morning, winds will subside under 10 mph
in some locations. If sky cover can begin to clear out, the
northwest Panhandles may experience low temperatures as low as 35
to 36 degrees with upper 30s to lower 40s elsewhere. Will have to
watch closely and see if the northwest Panhandles could
experience a frost that could impact outdoor vegetation. Areas
along a line from Dumas, TX to Eva, OK and points west will have
the greatest chance of some patchy frost at this time by the
pre-sunrise hours early Sunday morning.
Meccariello
LONG TERM...Sunday through Thursday...
Mid-level troughing to the west and ridging off the east coast
lead to southwest flow aloft Sunday. At the surface, high pressure
settles over the Southern Plains. As the high shifts southeastward,
the Panhandles will see southerly flow return and moisture
advection take place. Moisture fills in and precip chances
increase starting Sunday night through Wednesday afternoon.
Several GEFS members and a couple EC members show some precip
chances starting Sunday night, but deterministic models keep us
dry till Monday daytime. This is also when almost every EC and
GEFS member comes on board with precip in the area. A cold front
looks to push into the Panhandles Monday night, which will provide
the needed lift for the showers and thunderstorms. Models don`t
show much for instability and several models show quite a bit of
CIN to prevent these from becoming a widespread severe weather
event.
The post frontal environment for Tuesday appears to remain fairly
moist with precip coming out of the mountains and getting to the
Panhandles later in the afternoon and evening. Long range models
have some disagreements on timing of the next cold front and the
transition of the mid-level trough axis across the area, but it
should be sometime between Tuesday night and Wednesday. When this
occurs, dry air will fill in and the precip chances will end. The
latter half of the work week will see northwest flow aloft take
over as ridging fills into the western CONUS.
Beat
&&
.AMA Watches/Warnings/Advisories...
TX...Red Flag Warning until 8 PM CDT this evening for the following
zones: Deaf Smith...Oldham...Palo Duro Canyon...Randall.
OK...None.
&&
$$
88/88
Area Forecast Discussion
National Weather Service Denver/Boulder CO
712 PM MDT Fri May 20 2022
.UPDATE...
Issued at 712 PM MDT Fri May 20 2022
For the most part the the snow is going as planned. A heavy band
forced by 700-500 mb frontogenesis is draped across the Palmer
Divide into Washington County. We`ve adjusted the additional
snowfall totals to reflect 3-7" associated with this band through
tonight, with the higher totals along the Palmer Divide above
6,500 ft elevation where it`s significantly colder than areas to
the northeast. Latest CAM guidance and observational trends are
backing off any significant snow across the northern parts of
Colorado, especially Larimer and Weld Counties. We knocked
additional snow totals back quite a bit in those areas, especially
east of the Front Range where now we are thinking an inch of
additional accumulation for Fort Collins and another 1-4" for
Estes Park. The snow totals south of RMNP look on track for the
mountains, foothills, and mountain valleys and for the most part
left those additional totals alone. Thus the Fort Collins and NW
Weld County forecast zone was dropped to an advisory. The reasons
this event is far from over is that the sun is setting in an
hour, there will be a decent coupled jet structure overhead a
little before midnight, and the short wave trough is still to the
west. Platteville profiler is showing a deepening upslope, but
weaker in the lowest km. As long as the upslope remains 15-30 kts
in the 1-3 km range AGL, snow will continue especially across the
east slope foothills, Palmer Divide, and west metro Denver and
Boulder. Mesoscale jet-induced lift should begin to weaken around
midnight, and QG lift from the approaching short wave trough
should also wane very early Saturday. However, some instability
and weak upslope should keep the light snow going until 7-10 AM
across all but the highest elevations. Additional accumulations of
5-10" are possible across the foothills and higher mountain
passes mainly from Boulder County south, including US-40 around
Berthoud Pass, I-70 corridor, and US-285. Much less snow is
expected across the west slope mainly north of the north of the
middle Fraser Valley and the Colorado River. An additional 2-6"
are possible in metro Denver, with the highest totals west and
south of Denver proper.
Because the sun is about to set, we are seeing adverse travel
impacts in most mountainous areas, and slick conditions should
spread east to the I-25 corridor and Palmer Divide between now and
late evening. We have already received numerous reports of
bending trees and some branches snapping, so power outages are
still possible later this evening as well in the areas that
receive an additional 3 or more inches. Road conditions will
improve dramatically Saturday morning within a few hours after
sunrise.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 255 PM MDT Fri May 20 2022
The forecast remains largely on track this afternoon as an
significant winter storm continues to impact the region. A
reinforcing cold air surge raced across the plains over the past
couple of hours, and the resulting ~3F change in wet bulb
temperature has been enough to transition much the Denver metro
over to snow. In fact, several areas from Boulder down into the
southeast side of the metro have noted moderate to heavy snow with
accumulations already beginning on grassy surfaces. Over the past
45 minutes, a well defined subsidence zone has developed from
downtown Denver towards Fort Morgan in between two of the stronger
snow bands, which has temporarily stopped snow in those areas.
While things have gone according to plan so far, the forecast for
the rest of the afternoon and overnight remains quite
complicated. Aloft, the departing 140kt upper jet streak should
slowly drift south and east this evening, while a second, lesser
speed max enters central Colorado. For the next several hours, the
region should benefit from the lift from these coupled jet
streaks, with the best forcing slowly sinking south towards the
Palmer Divide overnight. Meanwhile, cold mid-level air will
continue to filter in from Wyoming with north-northeast upslope
flow remaining in place. Strong 700-500mb FGEN will also provide
an additional source of lift this evening as it shifts
southeastward. All of these ingredients point to a classic setup
for heavy, banded snowfall across the Foothills and urban corridor
southward into the Palmer Divide.
There are two areas of uncertainty with the afternoon package:
(1) the northern extent of the upslope & banded snowfall through
the overnight hours, and (2) how efficient snowfall accumulations
will be in the lower elevations. The HRRR continues to be
remarkably consistent with the northern edge of the precipitation
shield - roughly from Estes Park to Ft. Collins to Hudson to
southern Washington county - with roughly 0.5-1.25 inches of QPF
falling between 3pm to 6am south of there. I am skeptical that
snow will set up this far north, especially with a well defined
jet-band already trying to push east of Estes Park. We shifted our
forecast south to better reflect these trends, but there is still
quite a bit of uncertainty for Estes/RMNP and into the Fort
Collins area with regards to how much upslope snow can develop
later tonight. Meanwhile, we`ve already seeing fairly efficient
snowfall accumulation outside our window in Boulder during peak
heating/sun angle hours. Assuming upslope/banded snow continues
after sunset, there shouldn`t be much stopping snow from
accumulating on grassy surfaces and trees. Have bumped up snowfall
totals slightly for the southern Foothills and Denver metro
accordingly.
Upslope will continue through at least midnight before gradually
tapering off as the better moisture, upslope flow, and upper level
support all shift out of the area. There should be at least some
light snow showers continuing across the Front Range and Foothills
on Saturday, but accumulations during the day will be minor.
Tomorrow`s highs will make it back into the 40s to low 50s over
the plains, with 20s to 30s likely in the high country. Snowfall
totals are still expected to range from one to two feet across the
Foothills, especially Boulder county south, and 10-20" for the
Palmer Divide. Across the Denver metro, 5-10 inches of snow
appears likely, with a sharp gradient running from Longmont - DIA
- eastern Arapahoe county. As is usually the case with banded
snowfall events, there will almost certainly be locally higher
(and locally much lower) totals in the warning areas.
.LONG TERM...(Saturday night through Friday)
Issued at 224 PM MDT Fri May 20 2022
Saturday evening, there will be zonal flow aloft at the base of
the upper trough with a strong jet still overhead. Expect isolated
to scattered showers, focused on the southern Front Range
mountains and foothills and Palmer Divide, through Saturday night.
Precipitation will be light, with a mix of rain and snow
dependent on temperatures. There may be some banding but
significant accumulation is not expected. Overnight low
temperatures will be in the teens to lower 30s across the area.
There may be patchy or areas of fog on the plains late Saturday
night and early Sunday morning depending on how much skies clear
out, light winds, and high humidity, but based on the most recent
forecast data this seems less likely.
Sunday, flow aloft will be gradually decreasing and turning more
southwesterly ahead of an incoming shortwave, which will force
scattered afternoon showers favoring the high terrain. A warming
trend begins, and high temperatures will increase to the 50s on
the plains and mostly 30s and 40s in the high country. Showers
will increase in coverage and intensity through the evening and
peak synoptic scale forcing should occur around midnight. QG omega
fields show 10 to 15 mb/hr of ascent across the area.
There`s actually pretty decent agreement between the long term
models for the week. Monday, that shortwave should move over and
keep scattered showers going for most of northeast Colorado.
Snowfall should be almost confined to the mountains by this time.
High temperatures look to increase to the 60s on the plains. On
Tuesday, a deeper trough should be moving over Colorado and by
Tuesday night models show synoptic ascent turn to subsidence
behind the trough axis, then a northerly jet overhead Wednesday
afternoon and evening between the trough and following ridge.
Right now it looks like it will be warm and dry again under
ridging aloft on Thursday and Friday, and elevated fire weather
conditions probable across much of the lower elevations again as
well. However, another trough may coming in over the west coast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 545 PM MDT Fri May 20 2022
The snow will continue tonight through about 8-9 AM Saturday
morning. A few rounds of moderate snow are possible at all the
terminals from now until midnight or 1 AM, after which the snow
rates will be much lighter (more like flurries off and on during
the later morning hours). ILS conditions will persist into
Saturday midday. During the heaviest snow tonight CIG/VIS should
still remain above LIFR, generally 1/2SM and CIGS as low as 003 at
DIA and APA but only temporarily that low. CIGs could get a
little lower at BJC. CIG/VIS should slowly improve throughout the
night. Winds won`t be an issue as speeds should remain 3-6 kts out
of the WNW after midnight until late morning Saturday. The low
clouds may finally scatter out by early afternoon Saturday, with
winds light out of the southeast turning southwest by the evening
hours. Snow accumulation on the runways is likely from 8 PM
through about midnight, but minimal accumulations are expected at
DIA, and 1-3" on runways at BJC and APA are possible.
&&
.HYDROLOGY...
Issued at 224 PM MDT Fri May 20 2022
Sunday afternoon and evening, scattered showers will pose a
limited threat of flash flooding to the Cameron Peak burn area.
Precipitation amounts should be marginal and snow on the ground
should limit any flooding activity.
Persistent showers this week, mostly in the afternoon and
evening, should bring generally light precipitation and pose very
low threat of burn area flash flooding.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 10 AM MDT Saturday for COZ038>051.
Winter Storm Warning until noon MDT Saturday for COZ030-032>037-
039>041.
Winter Weather Advisory until noon MDT Saturday for COZ031-045-
046.
Winter Weather Advisory until 9 AM MDT Saturday for COZ038.
&&
$$
UPDATE...Schlatter
SHORT TERM...Hiris
LONG TERM...EJD
AVIATION...Schlatter
HYDROLOGY...EJD
Area Forecast Discussion
National Weather Service Cheyenne WY
918 PM MDT Fri May 20 2022
.UPDATE...
Issued at 918 PM MDT Fri May 20 2022
Winter weather headlines were cancelled this evening as snow
shower activity decreased in coverage and intensity. The majority
of the models show light snow moving south of I-80 into northern
CO tonight. Additional accumulations of less than a half inch
lower elevations and one to three inches above 8500 feet will be
possible. No changes to the current Hard Freeze/Freeze Warnings
as low temperatures are expected to lower to between 20 and 30
degrees early Saturday morning. Added frost across central and
northern portions of the CWA.
&&
.SHORT TERM...(Tonight - Saturday Night)
Issued at 330 PM MDT Fri May 20 2022
Snow has continued to diminish in coverage & intensity through the
last several hours as the elongated H5 vorticity lobe shifts south
into Colorado. Main plume of mid & high-level moisture now bisects
the CWA from SW-NE from the Snowy/Sierra Madre ranges in southeast
Wyoming to near Chadron in the northern Nebraska Panhandle. A good
bit of clearing is occurring northwest of that line per the latest
day/cloud phase RGB from GOES-16. The higher sun angle for late in
May has kept impacts fairly low for the most part, outside of some
morning road closures over the higher terrain between Cheyenne and
Laramie per WYDOT. Area webcams suggest there has been quite a bit
of improvement recently, and this will likely continue as the main
threat area shifts south into Colorado and some sunshine begins to
peak through. High-res guidance including the HRRR suggests little
in the way of additional accumulations for most areas, between one
half and one inch along/south of I-80 from Elk Mtn to Cheyenne.
Winter Storm Warnings have been cancelled for the South Laramie
Range and adjacent foothills. The other headlines will be allowed
to continue, but may be able to cancel these later this evening.
Near-record low temperatures and a hard freeze still appear likely
for much of southeast Wyoming and western Nebraska tonight through
early Saturday w/ the NAEFS continuing to show H7 temperatures at/
near climatological minimums around -10 deg C. Some guidance hints
at potential low-stratus development overnight which could lead to
a very tricky overnight low forecast with high bust potential. Not
really buying the likelihood of stratus just yet given a some-what
dry boundary layer, but it is not impossible. No doubt, this would
keep lows several degrees warmer than forecast. Nonetheless, opted
for the colder forecast given the unseasonably cold air mass which
has worked into the region. The latest grids reflect a good bit of
weight toward the 10th percentile of the NBM spectrum for lows. No
changes were necessary to inherited freeze highlights.
.LONG TERM...(Sunday - Friday)
Issued at 330 PM MDT Fri May 20 2022
The early part of the long term forecast will be characterized by
cool and unsettled weather continuing, while much warmer and drier
weather will work in late next week.
A broad trough will be positioned over the western United States
on Sunday. The initial shortwave responsible for today`s snowfall
will be pushing eastward across the plains, while another
shortwave dives into the Pacific northwest. Low level winds shift
around to southerly ahead of this system and will help to advect
increased moisture aloft into the area. Dewpoints will creep up,
but the low levels will remain fairly dry. The 500-mb vorticity
maximum will shift overhead late Sunday night, bringing increased
lift ahead of it. Thus, expecting scattered showers to develop and
bring some thunder. Some isolated showers and storms are possible
on Monday on the backside of the departing shortwave. Another weak
vorticity maximum will push through on Tuesday and provide some
lift mainly over Wyoming.
Concerning temperatures, we remain cooler than average through
midweek. 700-mb temperatures will generally fall in the 0 to -5C
range through Wednesday. Odds seem to favor the frost/freeze
threat diminishing for locations east of the Laramie range after
Sunday morning, but can`t rule out continued freezes in the higher
elevations. The 10th percentile of the NBM continues to show sub-
freezing lows in Cheyenne both Monday and Tuesday nights, while
the 50th percentile remains around 35F. Freezes are more likely
west of the Laramie range through Wednesday morning.
Starting on Wednesday, the broad trough will shift east, allowing
ridging to build back in across the Rockies. Thus expect warming
temperatures and drier conditions for the second half of the week.
The ECMWF brings in a stronger and more persistent ridge with
700-mb temperature climbing up to +15C by Friday, whereas the GFS
is a little narrower and less amplified. The ECMWF solution brings
temperatures on the warm end with highs in the upper 80s to even
90s east of the Laramie range, while the GFS is slightly
cooler. Regardless, above average temperatures will become favored
for Thursday and Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 449 PM MDT Fri May 20 2022
Current radar imagery has a bulk of the rain/snow pushing
southward along the boundary, with the snow/rain shower coverage
decreasing from the northwest to the southeast. Main concerns
over the next 24 hours exist with some dropped ceilings in the
overnight hours and a slight chance for lingering precipitation
across southeastern Wyoming and portions of the Nebraska
Panhandle. Confidence is on the low end for both ceilings and
additional precipitation chances with a relatively dry boundary
layer, but cannot rule out the possibilities with the recent
precipitation that fell.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Fri May 20 2022
Cooler temperatures for the next several days will keep fire
weather concerns low. Scattered showers and thunderstorms return
to the forecast on Sunday afternoon. Cool and unsettled weather
continues through Tuesday. A gradual warm up is expected to begin
on Wednesday, and above normal temperatures are likely by Thursday
and Friday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Hard Freeze Warning until 9 AM MDT Saturday for WYZ101-102-
104>111-113-115>119.
NE...Hard Freeze Warning until 9 AM MDT Saturday for NEZ020-054-095-
096.
Freeze Warning until 9 AM MDT Saturday for NEZ002-003-019-021-
055.
&&
$$
UPDATE...MAJ
SHORT TERM...CLH
LONG TERM...MN
AVIATION...MRD
FIRE WEATHER...MN
Area Forecast Discussion
National Weather Service Des Moines IA
640 PM CDT Fri May 20 2022
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Friday/
Issued at 314 PM CDT Fri May 20 2022
Forecast Highlights:
-Much cooler over the weekend, especially Saturday with light rain
showers
-Isolated frost possible early Sunday, only full dry day otherwise
-Rainy work week ahead, best chance for appreciable rainfall Tuesday
to Wednesday
GOES satellite imagery depicts an abundance of cloud cover across
the upper midwest this afternoon, with the departing cold front
tracking east over Illinois and eastern Wisconsin with the
associated upper level low. Despite the ever present cloud cover,
daytime heating allowed for temperatures to rise into the upper 50s
to low 60s across Iowa, which compared to the more summerlike
conditions in the 80s yesterday, is quite a change. Dry
conditions will return for all into the late afternoon to evening,
with breaks in the clouds expected for most areas later in the
day and keeping quiet weather for the rest of the day. Periods of
breezy conditions will continue with winds out of the northwest
behind the front, with cold air advection allowing for much cooler
air to arrive across Iowa, bringing below average temperatures
for the upcoming weekend. Overnight temperatures into Saturday
morning are expected to fall into the 40s. The dry weather wont
last very long, as a shortwave trough over the Pacific Northwest
arrives into the Central Plains into early Saturday, bringing
another round of rain showers across much of the state. The cooler
air overhead will limit the instability needed for storms, as the
HRRR and RAP models depict CAPE values under 500 J/kg, mainly
favored across far southeastern Iowa. Overall, a few rumbles of
thunder are possible with these showers, which are expected to
occur on and off through the day before ending in the evening.
Well below average high temperatures are expected for the season
Saturday, with values only reaching into the 50s across Iowa.
Sunday will be dry as a large surface high pressure system enters
the region from the Canadian Province. This will aid to reinforce
the cooler air over the region, as lows are expected to drop into
the upper 30s to 40s. Isolated frost is possible early, given the
cooler temperatures, clearing skies and light winds expected, but
would be brief before eroding after sunrise. Sunny conditions
with improving temperatures will occur Sunday, with highs in the
upper 50s to the northeast and in the 60s across the rest of the
state.
Cooler, dreary and rainy will be the theme for much of the next work
week as multiple systems are slated to push across the region. The
first of the week will be a mid-level shortwave trough developing
out over the western CONUS, tracking northeastward into the Central
Plains Monday. This will bring rain showers by Monday afternoon
through the evening, though overall lower end accumulations are
expected with this system under a quarter of an inch. A much deeper
trough will follow right after this system though, paired with a
northerly surge of moisture and associated surface low. This midweek
system currently has the greatest potential to bring more
appreciable rain accumulations Tuesday into Wednesday. WPC guidance
along with the NBM suggests that accumulations may reach upwards of
1 to 2 inches of rain, mostly concentrated along the south/southeast
half of the state. Ensemble guidance does show some uncertainty with
the placement of the system, with some suggesting this to be a more
widespread event across the state, while more model members favor
this system mainly impacting the southeastern half of the state.
Confidence on the placement of the system and total rainfall is
expected to increase in the coming days. Storm chances are on the
low end at this time, as cooler conditions will again limit the
available fuel needed for storm development, which would be most
likely Tuesday if any storms were to develop. Lingering rain showers
on the backside of the departing low Thursday may occur based on
recent input from long term model guidance, though additional
accumulations look to be minimal at this time. Temperatures will see
little improvement through the majority of the week, with overnight
lows in the 40s to 50s and highs in the 60s. A dry day will finally
make a return across Iowa by Friday with slightly warmer
temperatures nearing the 70s as an area of narrow ridging moves
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 637 PM CDT Fri May 20 2022
VFR conditions expected overnight with showers affecting southeast
terminals by 12z. Uncertainty remains in northward extent in
showers. MVFR cigs may occur with showers.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Bury/Krull
AVIATION...Jimenez/Martin
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT Fri May 20 2022
.AVIATION...
A cold front will slowly slide south across Se Mi overnight.
Clusters of thunderstorms will occur on the cool side of the sfc
front within the elevated frontal zone through much of the night,
affecting mainly MBS and FNT. Low level moistening along the cool
side of the front will support some low stratus development (MVFR)
late tonight into early Sat morning. Ceiling heights in all
likelihood will be highly variable across Se Mi during the course of
the morning.
For DTW...Metro continues to bee more influenced by the mid level
anticyclonic flow now over the eastern Great Lakes, which will hold
nighttime convection northwest of Detroit. The elevated frontal
boundary will reside over metro on Sat, suggesting chances for
showers and perhaps a few thunderstorms throughout the day.
.DTW THRESHOLD PROBABILITIES...
* Moderate in ceilings below 5000 feet overnight, high Saturday.
* Low in thunderstorms Saturday morning. Moderate Saturday
and evening.
&&
.PREV DISCUSSION...
Issued at 813 PM EDT Fri May 20 2022
UPDATE...
The 00Z DTX sounding showed a strong inversion based just above
850mb with very steep mid level lapse rates above this inversion. It
was this inversion that inhibited deep surface based convection
across Se Mi this afternoon. The robust convective response occurred
north of the cap across northern Lower Mi. The cold front is already
advancing into the Saginaw Valley and will slowly move across Se Mi
tonight. While sfc based convection will be inhibited through the
night, the cluster of thunderstorms now advancing across the
Muskegon area is occurring within the elevated portion of the front.
Several weak mid level short waves embedded within the southwest flow
along the elevated front will support convection tonight, mainly
across the northern portions of the forecast area. The steep mid
level lapse rates will contribute to respectable elevated instability
on the order of 1500-2k J/kg. So some of the stronger convection may
still pose a large hail risk and perhaps and isolated strong wind
gust.
PREV DISCUSSION...
Issued at 433 PM EDT Fri May 20 2022
DISCUSSION...
Main risk for severe weather exists along and north of M-46 from
6 PM this evening until 3 AM Saturday...
Latest ultra HiRes WoFS 18 member suite suggests convection remains
northwest of the CWA until 21Z today as a dynamic cold front works
across portions of Lake Michigan and western Lower Michigan.
Upstream FGEN response has been robust with increasingly organized
linear convection and some supercell development out ahead of the
main line. Meanwhile, well discussed low-level stability is
currently in place over most of Southeast Michigan with patches of
diurnal cumulus in the sub-inversion layer. MLCIN builds in excess
of 200 J/kg as elevated CAPE trends toward the 1750-2000 J/kg range.
The absence of meaningful forcing with the resident warm sector
limits the likelihood of storm development, even as dewpoints climb
into the mid-upper 60s. Initial convection begins across the
northern tier of counties (Midland/Bay/Huron) with some of the
latest HRRR runs suggesting CI may be delayed until 00Z. Strong 0-6
km bulk shear and CAPE look favorable for strong to severe storms
Main threat is one inch diameter hail and gusts to 60 mph. Still
monitoring the potential for surface-based convection as MLLRs peak
on the order of 8.0-8.5 C/km. Main area would be far NW Midland and
Bay counties where supercells could develop before midnight.
Although tornadic potential remains low with only mildly conducive
hodographs, a confirmed tornado touched down north of the area, in
Gaylord.
Forward progress of the cold front slows overnight with minimal
reorientation or translation of the parent longwave feature. This
transitions the front into a stationary feature resulting in a
longer duration of weak convergence while axis of higher moisture
settles across Lower Michigan. This higher ThetaE environment
sustains weaker convection beyond 3 AM holding mainly along/north of
I-69. As the severe potential wanes from collapsing ELs and
reestablished inversion/stable layers, showers are still expected to
continue in scattered fashion early Saturday morning with some
embedded thunderstorms. Winds also decrease significantly with the
departure of the LLJ.
Lower column flow veers west Saturday eventually drawing in cooler
Canadian air cyclonically which should hold temperatures in the 70s.
Instability reservoir redevelops with low-mid level moisture flux
over a more limited area. Shear parameters look more favorable than
instability, but at least a minor severe wind risk along/south of I-
94 until late evening is warranted with appropriate removal of
Slight Risk via SPC DY2 outlook. Scattered showers continue for the
Metro area until midday Sunday while there is still synoptic scale
divergence aloft. The stationary jetstreak then fully dislodges and
allows the front to move east resulting in decreasing coverage of
rain by early Sunday afternoon. Subsidence and high pressure fills
in behind the front with colder feed of air in place Monday and
Tuesday under anticyclonic flow. Next low and chance for rain
arrives Tuesday into Wednesday along with a minor warmup after a
couple days with highs in the 60s.
MARINE...
Active marine weather persists for the remainder of the afternoon
and evening periods. Strong thunderstorms currently upstream over
Lake Michigan will track eastward into northern Lake Huron over the
next several hours, in which mariners should be prepared for large
hail, gusty winds, elevated wave heights, and frequent lightning.
Further south, Small Craft Advisories continue in the wake of a
strong low level jet supportive of 30 knot gusts. While cooler lake
temperatures and associated stability keep the majority of gusts
below gales, isolated gusts to gales cannot be ruled out,
particularly close to the shoreline. Gusts diminish overnight with a
directional shift to NW flow as a cold front sags southeast.
Additional shower and thunderstorm development is possible this
evening and overnight along and ahead of the front, with widespread
rain continuing into Saturday as the front stalls over lower Mi.
Quiet and dry conditions emerge Sunday as high pressure builds in
with prevailing northwest flow.
HYDROLOGY...
A cold front arrives this evening producing increasing coverage of
showers and thunderstorms. Most of the heavier rainfall holds to the
north until late tonight with up to 0.25 inches possible. Major
revisions made to Saturday rainfall with longer periods of drier
weather now expected. Total rainfall Saturday and Saturday night is
on the order of 0.25 to 0.50 inches. Widespread flooding is not
expected given the prolonged duration of rainfall, but areas that
receive heavy downpours from storms that arrive in quick succession
could see ponding on roadways and in poor drainage areas.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....99
UPDATE.......SC
DISCUSSION...KK
MARINE.......MV
HYDROLOGY....KK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Goodland KS
535 PM MDT Fri May 20 2022
.UPDATE...
Issued at 530 PM MDT Fri May 20 2022
Expanded the Frost Advisory another row of counties east as recent
runs of guidance indicate more of an eastward propagation for the
area of precipitation. 21Z RAP Wet Bulb analysis indicates the
rain/snow line will make it into portions of Hitchcock, Rawlins,
Thomas, Logan and Wichita counties. If any snow were to occur it
would be precipitation driven and would allow for a few degrees
of cooler temperatures than forecasted to occur around sunrise.
The timing of the rain/snow has also been moved up a few hours as
webcams are currently showing all snow occurring in Last Chance,
Colorado.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 247 PM MDT Fri May 20 2022
Across the region this afternoon, skies are a mix of sunny to mostly
sunny in the east and southeast, to mainly cloudy skies working
north and west. There is currently a wide range in temperatures with
40s and 50s under the thickest cloud cover, and upper 60s to around
70F for areas seeing the most sunshine. Overall, a northwesterly
wind is blowing over the entire area, with gusts around 30 mph at
times.
For the remainder of the afternoon, expecting cloud cover to remain
intact across the north and west, expanding over the entire area as
the evening progresses. The latest RAP40 500 mb analysis is showing
a shortwave moving across the central Rockies, and a surface low
over south central Colorado and a surface ridge to the northwest
nosing into the Plains.
This will lead into the weather concerns for tonight on into
Saturday. Currently there is some light rain falling over portions
of northeast Colorado and latest models show this to enhance and
grow in areal coverage overnight. This will be in tandem with temps
slowly falling as well, especially over northeast Colorado. The
result will be any rain falling to mix with and even change over to
light snow, with possible accumulations up to a couple inches in
Colorado. Some trace to a couple tenths are possible closer to the
NE/KS border.
Of concern will be the very warm ground temps around 60F currently
over the area. This will allow for melting on roadways, but some
accum on other raised surfaces. Potential for some locally heavier
snows at times that could briefly overwhelm surface temps. Overall,
did not issue a Winter Wx Advisory but will monitor later this
evening and next shift may issue if warranted.
With the current forecasted lows however, did issue a Freeze Warning
for northeast Colorado and also a Frost Advisory for adjacent KS/NE
for 06z-15z Saturday. Added in patchy frost but is contingent on
strength of caa south and cloud cover/precip.
Precip will taper off during the morning hours for the most part on
Saturday, but lingering moisture will impact northeast Colorado for
additional moisture into Sunday. Will have to monitor clouds for
potential frost/freeze products Saturday night/Sunday morning as a
good portion of the area could be impacted.
For temps, colder air working south into the cwa will have a wide
range for lows tonight, with around 30F in the west up to the low
40s east. This will give way to highs on Saturday in the mid 40s
west to mid 50s east. Colder temps west potentially affected by any
remaining colder air and even snow, if it survives the warm ground
temps. Going into Saturday night, mainly 30s are expected, with
upper 50s west into the mid and upper 60s going east on Sunday.
With the cold overnight temperatures tonight and again Saturday
night, wind chill readings come into play. For tonight into Saturday
morning, readings as low as the 20s mostly with some 30s east of
Highway 83. For Saturday night into Sunday morning, mainly 20s in
Colorado and 30s elsewhere.
.LONG TERM...(Sunday night through Friday)
Issued at 159 PM MDT Fri May 20 2022
For this long-term forecast period, the weather pattern will
unsettled with cool, cloudy, and showery weather anticipated.
However, the pattern looks to change with a ridge building in from
the west, resulting in a return to warm, dry weather.
Beginning with Sunday night through Wednesday night, a trough of low
pressure looks to stall out over the High Plains as a high pressure
block forms over the southeastern United States. As a result, cool,
cloudy, and showery weather should persist over the high plains as
disturbances rotate through the flow overhead. As another lee
cyclone forms along the Rockies, south flow will return and bring
slightly warmer temperatures back to the region for the start of the
work week. The most substantial disturbance to impact the Plains,
and thus bringing the best chance for precipitation, will eject east
from the Rockies on Monday night. After that, chances for
precipitation will slowly wane, and perhaps approach zero sooner
than currently anticipated depending on where the surface
low/surface features end up. From Sunday night through Wednesday
night, precipitation with the showers/light steady rainfall will be
on the order of one quarter to three quarters of an inch. This
beneficial rainfall will certainly help the green-up process kick
into a higher gear, but will not do much to bust the current drought
conditions that continue to expand across the region.
Beginning on Thursday, a ridge of high pressure will begin building
over the region from the Desert Southwest. As this happens, a
noticeable increase in temperatures and a clearing of the skies/end
of the precipitation will be observed. By the end of the week, it`s
quite possible that we once observe temperatures in the 90s, a
drastic change from this weekend and the first half of next week.
The 6-10 day and 8-14 day outlooks indicate above normal
temperatures will persist, so this pattern change seems as though it
will stay around for a while. As the ridge builds, it doesn`t
currently seem like there will be any substantial disturbances that
may lead to thunderstorm development. That being said, with the
southerly flow from the Gulf and the warmer temperatures, the
atmosphere should become more conducive for thunderstorm activity so
any subtle shortwave troughs, which can not be discerned at this
time, will need to be watched for potential strong/severe
thunderstorm development.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 456 PM MDT Fri May 20 2022
VFR ceilings are currently present at each TAF site and are
anticipated to persist through the first 5-6 hours of this TAF
period. Ceilings will become MVFR around or just after 06Z at KGLD
as a band of frontogentical precipitation moves towards the
Kansas State line. The precipitation will start out as all rain
before becoming all snow around 10Z with IFR ceilings looking
likely. Confidence is low in how far east the precipitation will
survive so left VCSH at KMCK for now with ceilings becoming MVFR
around sunrise.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Frost Advisory from midnight MDT /1 AM CDT/ tonight to 10 AM MDT
/11 AM CDT/ Saturday for KSZ001-002-013-014-027-028-041-042.
CO...Freeze Warning from midnight tonight to 10 AM MDT Saturday for
COZ090>092.
NE...Frost Advisory from midnight MDT /1 AM CDT/ tonight to 10 AM MDT
/11 AM CDT/ Saturday for NEZ079-080.
&&
$$
UPDATE...TT
SHORT TERM...JN
LONG TERM...RRH
AVIATION...TT
Area Forecast Discussion
National Weather Service Lake Charles LA
932 PM CDT Fri May 20 2022
.DISCUSSION...
Made some minor modifications to the pop grid as not expecting any
significant shower activity until Saturday afternoon. Otherwise,
mostly cloudy skies tonight with muggy temperatures.
Southerly winds will remain elevated over the coastal waters
through Saturday morning and extended the small craft advisory for
a few hours to reflect this.
Rua
&&
.PREV DISCUSSION... /issued 624 PM CDT Fri May 20 2022/
DISCUSSION...
For the 05/21/2022 0000 UTC TAF package.
AVIATION...
Mostly VFR conditions are anticipated through the period, however
MVFR ceilings may occur around sunrise for a few hours. Ceilings
will improve a couple hours after sunrise. Winds will be generally
south during the period, and gusty again Saturday.
05
PREV DISCUSSION... /issued 417 PM CDT Fri May 20 2022/
SHORT TERM [Today through Sunday]...
Some low-level clouds are currently in the area with temperatures
will above average and moderate relative humidity. The continued
onshore flow will lead to increase moisture in the area overnight
into tomorrow. Winds will be expected to be elevated overnight
which will likely inhibit any significant fog formation.
A frontal system will be expected to move through the area
Saturday into Sunday. The HRRR shows organized convective
thunderstorms moving through the area from Texas. The Storm
Prediction Center has parts of our area in a Marginal Risk of
Severe Weather Saturday and Sunday. HRRR soundings indicate
significant DCAPE values which suggest the potential for damaging
wind gusts. Large hail will be possible as well.
55
LONG TERM [Monday through Saturday]...
For the start of the long term high pressure will dominate from the
rockies to the mid Atlantic states and south to the gulf coast as a
stalled frontal boundary will be draped along the nw gulf coast.
Aloft a broad upper level trof will extend from coast to coast with
shrtwv ripping through this pattern. This will finally bring temps
drop back into the 30 climo range 85 for highs and mid 60s for
morning lows... more importantly this will step up a rain event
across the region for the week ahead.
Afternoon temperatures will hold in the mid 80s as clouds and rain
will cooled air... Monday. The stalled front is expected to lift
back to the north during the day into the eve hours with a sfc low
developing along the frontal boundary in north Texas. This will help
pull additional moisture from the gulf with PWAT`s around 1.75
inches and MUCAPE approaching 1100 j/kg.
Tuesday an upr lvl impulse is pushing into east Texas ahead of a
band of storms projected to make the Texas/ Louisiana state border
during the afternoon hours. The front slows keeping the region in
the warm slot into Wednesday morning. Showers and thunderstorms will
be scattered during the morning hours becoming better organized into
the afternoon as the front drops into the coastal waters. The ECMWF
has a similar overall signature but is holding the front along the
coast as gulf moisture streams in from the gulf and above the
boundary. The chance for showers will extend as the axis of the upr
lvl trof will be just to the west movg into se Tx around sunrise
with the front in eastern Louisiana. Therefore the chance for
showers and isolated thunderstorms will continue but will begin to
fade during the afternoon hours as the trof aloft moves into south
central Louisiana with sinking air aloft becoming established. The
good news is Thursday and Friday morning lows expected into the 60s
with clearing skies Friday and afternoon highs in the upr 80s.
19
MARINE...
A Small Craft Advisory will remain in effect through tomorrow
morning for parts of the area. Winds and seas will be elevated
over the next few days as a frontal system moves through the area.
Showers and thunderstorms will be expected as the front moves
through the area.
55
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Exercise Caution through Saturday morning for GMZ430-
432-435-455-475.
Small Craft Advisory until 10 AM CDT Saturday for GMZ450-452-470-
472.
&&
$$
Area Forecast Discussion
National Weather Service New Orleans LA
441 PM CDT Fri May 20 2022
.SHORT TERM...Another quiet and warm day. There have been a few
light showers across coastal MS but most of the area remained dry
while the strong storms stayed off to our east.
Activity will pick up considerably over the next 72 hours but the
one time frame that is in question is tomorrow. Quite a bit of
uncertainty with how much convective development we see tomorrow
along with the threat of a few strong to possibly severe storms. A
lot depends on what set of models you trust tomorrow and there is no
real agreement with any of the reliable guidance. Even the
ensemble means from the GEFS and ECS are far apart, the MOS
between the 2 is as much as a 40-60% spread in PoPs, and that is
also leading to a decent spread in highs tomorrow. The NBM appears
to be weighted towards the ECMWF for PoPs but for highs tomorrow
it looks like a good blend. The GFS is almost completely dry
tomorrow but it does have isolated to widely scattered storms
still but the ECMWF has a strong easterly wave like system moving
through tomorrow and that does not agree at all with the pattern
we are in. The GFS has support from the 18z HRRR which is mostly
dry but the rest of the CAMs spread support across the board.
Looking at current obs and satellite, along with what would
typically happen, am leaning more towards the GFS.
Still quite the area of dry air over the western Gulf and much of
the Lower MS but that should start to improve overnight and more so
tomorrow. GOES16 TPW shows the very rich tropical air over the
Yucatan, east of the Yucatan and into the southeastern Gulf. Again
this atmospheric river (Maya Express) will push into the area but
this will come in from the southeast which the GFS is fairly on top
of that (the ECMWF again brings the moisture from east to west and
that is not what looking likely). The deep moisture will finally
push into the area midday/tomorrow afternoon and as the noses in we
may start to see some convection develop. Now the problem is with
convection likely having less coverage and taking longer to develop
we will get warmer and thus more unstable and there is enough other
ingredients that look interesting from a severe standpoint. Forecast
soundings across the northern half of the CWA are quite unstable.
Very high DCAPE values possibly in excess of 1300 j/kg. The will be
a CAP in place through the first half of the day and that should
help eliminate some storms till afternoon. There will be some mid-
level dry air initially to help in momentum transport. Mid-level
lapse rates don`t look to bad either; possibly greater than 7 C/km.
Mid-level support is not there so everything will be highly dictated
by daytime heating, sea/lake breeze, and outflow boundaries. This is
all is suggesting a threat of wet microbursts and that is why SPC has
put most of the area in a Marginal Risk. Freezing lvl is a little
high but h5 temps could be around - 10 to -11 C and that could also
lead to hail concerns.
Heading into Sunday and Sunday night and probably through much of
Monday the threat for heavy rain will increase. Moisture will
continue to pump into the region from the south and southeast with
PWs around 1.75 to 1.9". The weak front that will approach the
region tomorrow will likely stall over the CWA late Sunday with an
inverted trough remaining over the CWA through the night. Upper
level support won`t be strong but there will be some to work with as
the RRQ of the jet will be over the region Sunday and then possibly
a couple jet structure over the area Sunday night into Monday. The
We will continue to be unstable leading to a greater threat of
thunderstorms and not just showers. The combination of divergence
aloft and unstable conditions will enhance the rain potential making
storms rather efficient. Storm motion will be slow meaning heavy
rain for longer over some locations. The one rather positive thing
right now is the lack of any strong support. Mid level flow will be
with just a weak trough over the area or even just a weakness in the
mid levels. With no southwest flow aloft parallel to the sfc
boundary the threat of training is lower. WPC does have the entire
area in a Slight Risk for excessive rainfall Sunday and Sunday night
and it would not be out of the question to see a small area move
under a Moderate Risk for excessive rainfall at some point. /CAB/
.LONG TERM...Active weather should continue through much of the work
week as the pattern will be blocked across the CONUS. Good agreement
with the pattern from all of the reliable guidance but as always
there are some differences in the details. Stuck with the NBM for
the extended portion of the forecast.
Tuesday through Thursday will be dominated by southwest flow aloft
and multiple disturbances. The L/W trough over the central CONUS
will be blocked due to a strong ridge in the western Atlantic and
then multiple s/w`s dropping down the back side of the trough. As
each wave rotates around the base of the trough and through the
Lower/Mid MS Valley and to the northeast rain chances will increase.
The problem is timing these and the exact location and at that time
it is too difficult to even try to. That said we will hold on to
higher PoPs during the day mainly due to daytimes heating which in
itself should be enough to spark some storms given the ample
moisture we will still have over the region.
Uncertainty becomes greater late in the work week as some of the
guidance is a little slower with the L/W trough axis moving through
and continuing the threat for rain through the remainder of the
forecast while a few others are a little faster and start to dry us
out late Thursday. /CAB/
&&
.MARINE...High pressure will remain in control across much of the
eastern and northern Gulf with a sfc low developing over the
southern Plains. This should keep moderate winds in place across the
coastal waters tonight but the gradient should begin to weaken
tomorrow as the sfc low fills in some and a cold front slowly drifts
towards the region. The cold front will stall across the area Sunday
with an inverted trough developing over the northwestern Gulf and
then slowly retreating northwest early Monday. After that we should
move back under persistent southeast flow across much of the central
and western Gulf. That could remain in place till late Thursday
leading to a decent fetch for a prolonged period of time so seas
could be higher than typical with the winds being forecast.
&&
.AVIATION...18z TAF Package...for the next 18 hrs impacts should
be fairly minimal with the only concern really being low cigs after
midnight tonight and that is mainly over coastal MS (MCB) and
perhaps ASD in SELA. Again models are advertising low vsbys at MCB
but that did not occur this morning so hesitant to add that to the
TAFs at this time. after 13z all sites should be moving back into
VFR but low cigs will still be likely but these should remain north
of 3500 ft. Tomorrow afternoon convection may start to develop and
impact the region. /CAB/
.PRELIMINARY POINT TEMPS/POPS...
MCB 73 93 70 85 / 10 40 20 100
BTR 75 94 72 86 / 0 50 30 100
ASD 74 92 71 86 / 0 60 40 90
MSY 78 92 75 86 / 0 60 40 100
GPT 77 88 74 86 / 10 50 40 90
PQL 74 90 72 86 / 10 50 40 90
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
700 PM EDT Fri May 20 2022
...Updated Aviation Discussion...
.Short Term...(This evening through Saturday)
Issued at 340 PM EDT Fri May 20 2022
=====================================
Near Term (Now through 800 PM EDT)
Risks: Gusty southwest winds
Confidence: High
=====================================
Afternoon satellite imagery shows mostly sunny skies across southern
Indiana and central Kentucky with only a small Cu field observed.
Temperatures were generally in the mid 80s over across the Bluegrass
with generally upper 80s west of the US 27/127 corridor. Afternoon
temps should top out in the 84-89 degree range in most areas, though
Louisville metro will likely top out at 90-91. It has been a breezy
day with sustained winds of 15-20 mph with gusts to 30-35 mph at
times. We expect these gusty southwest winds to continue through
sunset and then taper off. Temperatures will cool down this evening
with most places remain in the lower 80s through 800 PM EDT.
======================================
Tonight (800 PM EDT to 800 AM EDT Sat)
Risks: None
Confidence: High
======================================
Moving into the evening hours, mostly clear skies are expected
across the region. Clear skies will continue into the overnight
hours. While the gusty winds will slacken off, surface winds will
remain a bit more elevated overnight with a gentle southwest breeze
expected. Low temperatures will average from the upper 60s to the
lower 70s. A few high clouds may work their way into southern IN
and western KY late tonight.
======================================
Saturday (800 AM to 800 PM EDT)
Risks: Thunderstorms (Strong/Severe)
Confidence: Medium
======================================
In the upper levels, a positively tilted upper trough axis is
forecast to be positioned from eastern Canada southwest into the
central Plains. The overall flow pattern aloft is slow and this
trough axis is not forecast to move eastward quickly. A rather long
cold front is expected to move slowly eastward from the upper
Midwest southwestward through the southern Plains. The latest
guidance suggests that this front will move rather slowly eastward
through the day on Saturday. In advance of the front, widespread
low-level moisture is expected to be in place across the Ohio
Valley. Model solutions vary on the quantity and quality of
moisture which will have an impact on surface based instability
developing. The NAM3K runs suggest dewpoints will be in the upper
60s to the lower 70s across the region, while recent runs of the
HRRR are quite a bit lower with low-mid 60s. This is likely due to
the HRRR allowing somewhat more robust mixing in the afternoon.
Partly to mostly sunny skies are expected early and that should lead
to a good amount of heating during the day with afternoon highs
topping out in the mid-upper 80s once again.
Convection evolution for tomorrow is still a bit unclear. However,
the general consensus of the models is that convection will likely
develop out to our west and gradually spread eastward into the
region during the afternoon hours. The best chances of
precipitation look to be in areas mainly west of I-65.
Model proximity soundings vary from model to model with HRRR showing
a bit more mixing in its proximity sounding across the region. The
HRRR soundings show your typical inverted V soundings in the low-
levels which is most likely why the HRRR has lower dewpoints than
say the NAM3K. NAM3K soundings do not have the inverted V soundings
and have dewpoints much higher in the lower 70s. As a result of the
higher dewpoints and temps, that model has much higher instability
values. Looking through other parts of the soundings, mid-level
lapse rates (700-500 hPa) remain quite steep in both models but the
overall bulk shear values remain < 30kts. The higher values of
shear are actually displaced well to our west. So the overall setup
is generally a high instability/low shear case.
Despite having/anticipating strong instability, it is rather
difficult to find a strongly forced mechanism for lift during the
afternoon hours. Bulk shear values are less than 30 kts, and the
most likely forcing would come from differential heating as better
slab forcing from the front remains to our west. So, multi-cellular
clusters of storms may develop across portions of the region, with
the highest risk mainly west of I-65. For now, plan on carrying
mainly 30-40% coverage west of I-65 with 20-25% coverage out east of
there. The multi-model consensus suggests the possibility of some
sort of more organized line of storms coming into the region
tomorrow night.
The main hazards with any storm Saturday afternoon with damaging
wind gusts and large hail given the rather steep mid-level lapse
rates and higher CAPE values within the hail growth zone.
.Long Term...(Saturday night through Friday)
Issued at 350 PM EDT Fri May 20 2022
Synopsis...The mean upper-level pattern for the next seven days will
feature a longwave trough slowly settling over the Central US while
several shortwave energy waves will ride its base, allowing further
amplification of the negative height anomalies. At the same time,
the trough will be flanked by ridging on both coasts which will
favor the moisture advection towards the lower Ohio valley along
with the mean storm track right overhead. Albeit there has been
considerable model variability handling the trough`s amplitude and
progression, it seems that the latest (20/12Z) deterministic model
runs are leaning towards the slower and deeper GFS solution. As a
result, expect periods of heavy rain and warming temperatures for
next week.
Saturday Night - Sunday...Best chance of storms for the weekend will
be focus during Saturday night into Sunday morning when a katafront
will sweep through the lower Ohio Valley. Currently, SPC has an
Slight risk of severe weather along the northwestern corner of our
CWA concerning wind and hail threats. However, hi-res models
indicate that the main convective line should be arriving right
after the diurnal instability maximum which can cause disruption of
the storms development as they sag southward. The best chance for
isolated instances of severe concerns will be if the line moves
faster to coincide with the best instability or if pre-frontal
storms form ahead of the line. Sunday morning will be characterized
by storms with lightning, strong gusts, and heavy rain being the
main threats since the PBL will be stable (according to forecast
soundings) and the best synoptic dynamics will stay up north.
Monday...Following a GFS-like solution, expect the main frontal
boundary to has pushed south of the Kentucky-Tennessee boundary,
enough to have a break from the rain/storms. Northeast winds will
keep temperatures in check as mins will fall to the low/mid 50s and
highs will stay around the low 70s. There will be some clearing
working out from southern Indiana and north-central Kentucky, but
clouds will hold over the Cumberland areas with an isolated light
shower during sunrise.
Tuesday - Friday...Several low-pressure waves are forecast to track
along the Ohio Valley as the main trough begins to lift northeast.
Periodic warm-sector rain and storms look possible over this period,
so flooding and potentially severe weather concerns would have to be
closely monitored during this timeframe. Also, soils might be
saturated by the second half of next week after several rounds of at
least moderate precipitation, allowing some rivers to rise above
action stage.
&&
.Aviation...(00Z TAF Issuance)
Issued at 701 PM EDT Fri May 20 2022
Gusty winds should begin to subside this evening as the nocturnal
inversion sets in. Winds just off the surface will still be strong,
and result in LLWS later tonight for all TAF sites.
Expect another day of breezy conditions tomorrow, though gusts
Saturday should be a little weaker (~20kts) compared to today. There
is the potential for showers/storms late in the period ahead of an
approaching cold front, but at this time coverage of precipitation
looks too limited to include in TAFs. The better chances for
showers/storms come tomorrow night.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Short Term...MJ
Long Term....ALL
Aviation...DM
Area Forecast Discussion
National Weather Service Memphis TN
917 PM CDT Fri May 20 2022
.UPDATE...
A tranquil night is occurring this evening across the Mid-South.
Expect this trend to continue through the remainder of the night.
The big question remains with the timing of showers and
thunderstorms tomorrow. The 18Z run of the HRRR had been bringing
in convection earlier in the afternoon than some of the other
CAMS. Latest runs seem to be backing off on this idea. Hard to say
what will happen until initiation of the storms occur. The storms
will definitely have the potential to be severe when they move
into the Mid-South due to the warm, moist and unstable airmass
that will be in place. Stay tuned for the latest. Made some minor
tweaks to temperatures, POPS, and cloud cover. Update will be out
shortly.
KRM
&&
.DISCUSSION.../issued 301 PM CDT Fri May 20 2022/
Gusty conditions continue across the Mid-South this afternoon.
Observations for areas along and west of the Ms River (advisory
area) indicate sustained winds 15 to 25mph with gusts of 35mph.
The current wind advisory will remain in place until 7pm this
evening. Dry and warm conditions will continue overnight with low
temperatures generally in the 70s.
The start of an unsettled weather pattern will return to the area
this weekend. A very broad upper level trough and slowing moving
surface cold front will begin to approach the area from the west
early Saturday. The best chance for rain across the Mid-South looks
to be Saturday night into Sunday in association with the surface
front. However, development of storms during the afternoon and
early evening hours on Saturday is not out of the question.
Sufficient surface instability (2000-3000J/kg) and ample moisture
(upper 60 to low 70s dewpoints) will be in place though shear and
lift will be slightly displaced back to the west. If storms can
get going during this time they could be strong to severe as well
with hail being a threat. SPC has upgraded the Mid- South to
either a Marginal (1/5) or Slight (2/5) Risk for severe
thunderstorms on Saturday. Primary threats include damaging winds
and heavy rainfall with a secondary hail threat. Similarly, WPC
has highlighted the Mid- South in a Marginal (1/4) to Slight (2/4)
Risk for Excessive rainfall for roughly the same area as the
severe outlook. Given that this will be a slow moving system with
sufficient instability and high PWATs 1.5 to 1.75 inches heavy
rainfall resulting in flash flooding is not out of the question,
Especially for areas along and west of the MS River, PWAT values
will exceed the 90th percentile on Saturday tonight. 1 to 2 inches
with locally higher amounts of rainfall will be possible primarily
along and west of the MS River. The main uncertainty with this
next system is storm development during the afternoon hours on
Saturday ahead of the front. Will need to continue monitoring this
potential in the short-term.
The cold front will push through the area on Sunday and stall to our
southeast. However, by Monday this front will lift back north as a
warm front bring more rain to the area. Expect on and off rain
chances and cooler temperatures through at least mid-week next
week. The next system of interest looks to impact the Mid- South
by mid- to late week. However, it is too early to get into the
specifics regarding timing and location. Stay tuned!
17
&&
.AVIATION...
VFR conditions continue overnight with S winds remaining elevated
at 10-12 kts. A brief MVFR deck is expected early Saturday
morning before scattering out by late morning with S wind becoming
gusty again. CAMs are all over the place with respect to
convection associated with the approaching cold front. There is at
least some chance of development during the afternoon though
better chances wait until Saturday night. Added a VCTS at MEM at
03z for now.
SJM
&&
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Spokane WA
403 PM PDT Fri May 20 2022
.SYNOPSIS...
Scattered showers and thunderstorms are forecast through Saturday,
with a slight warming trend through the weekend. Near seasonal
temperatures are forecast early next week, with a more substantial
warmup possible Wednesday and Thursday. Next weekend is looking
unsettled.
&&
.DISCUSSION...
Tonight through Sunday: A cold upper trough will remain over the
region into Saturday. This will result in more shower and mainly
isolated thunderstorm activity with the highest coverage during
the afternoon and early evening hours as the atmosphere
destabilizes with daytime heating. With the region under the
trough there isn`t much shear to work with so most of these storms
will be short lived producing brief downpours, gusty winds, and
small hail. Through the afternoon the highest coverage of showers
has been over North Central and Northeast Washington into the
North Idaho Panhandle with isolated lightning strikes. Going into
the evening a rain cooled outflow boundary will sag south which
will likely initiate new convection shifting south with time
towards the Ritzville, Spokane, and Coeur d`Alene areas and
potentially eventually the palouse. This activity should weaken
after sunset with the loss of daytime heating but with an upper
low over British Columbia dropping south towards the Cascades by
morning there remains enough mid level moisture and instability
for a chance of showers overnight into Saturday morning. The
atmosphere again destabilizes Saturday afternoon with a broad area
of instability over the region for another round of showers and
isolated thunderstorms. With the closed low tracking from the
Cascades into SE WA/Central Idaho on Saturday there should be
higher coverage of showers in these areas relative to NE WA/N
Idaho Panhandle. Saturday Night into Sunday the upper low pushes
out as a short wave ridge begins to nose in. However a few
mountain showers may redevelop Sunday afternoon over the northern
mountains and Idaho Panhandle as shallow instability lingers.
Snow has been falling today above 5000 feet in northern WA. Snow
levels will remain near this level into Saturday morning, with
snow levels rising to 6000 feet Saturday afternoon. Localized
accumulations will again be possible tonight and Saturday morning over
Sherman Pass especially under heavier showers. Given the localized
nature of the heavier showers will be ending the Winter Weather
Advisory this afternoon. JW
Sunday Night through Tuesday: Showers will quickly diminish Sunday
early evening. A broad ridge begins to move into the region.
Monday and Tuesday there is a chance of showers across the ID
Panhandle and extreme NE WA with a better chance of thunder Monday
than Tuesday. Low temperatures will be in the 40s with highs in
the 60s (low 70s for parts central WA), which is 1-3 degrees
below average for this time of the year.
Wednesday through Friday: More uncertainty comes into the
forecast. The ridge moves inland and we will see some warming. In
fact, the latest NBM is giving the Spokane airport a high of 72 on
Wednesday, with a 70% of seeing 70 degrees or warmer. That will
break the record of latest 70 degrees at Spokane. (the previous
record being May 21st in 1896) Thursday the uncertainty in the
forecast begins to become more noticeable. 30% of the ensembles
are showing the trough moving onshore with cooler temperatures and
some spotty mountain precip, while 70% are trying to hang on to
the ridge, which keeps us dry and slightly warmer. NBM is showing
a 80% chance of 70 degrees or warmer for Thursday for Spokane.
Friday most ensembles are showing the trough moving onto the west
coast or already moving into our area, with an increased chance of
showers and cooler temperatures. 16% of ensembles hold onto the
ridge with dry conditions and warmer temps. So, the issue in the
extended is the timing of the trough, and currently it looks like
Memorial Weekend isn`t looking so nice. /Nisbet
&&
.AVIATION...
00z TAFs: An upper level trough will promote showers over the
region into Saturday with the highest coverage during peak heating
(afternoon and evening). There has been enough instability for
isolated thunderstorm development and given recent lightning
trends have indicated VCTS in the Spokane area TAF`s as well as
Wenatchee through 02z-03z this evening. Wind shifts from
convection has already been observed today and will continue into
the evening with outflow gusts up to near 20 kts. HRRR shows a
wind shift reaching KGEG/KSFF/KCOE around 0030z- 0100z, with
potential wind shifts around KEAT/KMWH but confidence is magnitude
and timing is less so handled this with a variable wind forecast,
but some gusts to 15-20kts are possible at times. Best potential
for shower or thunderstorm activity for KPUW/KLWS will arrive
Saturday afternoon as an upper low moves over the area. Conditions
are expected to remain VFR through the period except for brief
MVFR conditions under heavier showers and isolated thunderstorm
activity. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 39 62 39 67 43 67 / 60 30 20 10 0 20
Coeur d`Alene 38 61 39 65 42 65 / 60 30 20 10 0 20
Pullman 37 59 39 63 42 65 / 20 40 30 10 0 10
Lewiston 43 66 46 70 47 71 / 20 40 30 10 0 10
Colville 38 64 37 70 41 68 / 50 30 20 10 0 20
Sandpoint 40 61 37 65 41 64 / 50 20 20 10 0 20
Kellogg 39 59 40 63 43 63 / 40 30 20 10 0 20
Moses Lake 42 67 41 73 47 75 / 30 20 20 0 0 0
Wenatchee 44 64 44 73 50 72 / 20 40 30 0 0 0
Omak 43 64 41 72 46 72 / 40 40 30 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Tulsa OK
951 PM CDT Fri May 20 2022
...New SHORT TERM...
.SHORT TERM...
(The rest of tonight)
Issued at 944 PM CDT Fri May 20 2022
Cold front has made very slow progress southeast this evening, and
currently extends from near Miami in far northeast OK to Okmulgee
into south central OK. So far convection has been slow to develop,
with a modest increase in post-frontal showers across northeast
OK over the past 1-2 hours. 00Z NAM and the most recent HRRR have
backed off a bit on frontal convection into the night, with the
bulk of storms likely remaining elevated behind the front. Elevated
instability and 0-6km shear will be supportive of a few severe
storms, with large hail being the main threat. Will also need to
monitor any locally heavy rainfall with training cells possible
through the night.
&&
.LONG TERM...
(Tomorrow through Friday)
Issued at 418 PM CDT Fri May 20 2022
Scattered showers and thunderstorms are forecast to be ongoing
across parts of the CWA Saturday morning as the frontal boundary
remains over the region. This boundary is expected to pick up
momentum during the day...entering Southeast Oklahoma and
Northwest Arkansas by early afternoon and finally exiting the CWA
Saturday evening. Ahead of the front...continued storm chances
with severe weather potentials are possible through Saturday
evening. Again locally damaging winds and large hail should be the
main threats. Behind the surface frontal passage...elevated
instability back to the 850-mb front will allow for lingering
shower and thunderstorm chances tapering off from northwest to
southeast Saturday evening through Sunday. The greater potential
for storms Saturday night into Sunday is forecast across parts of
Southeast Oklahoma into West Central Arkansas.
Sunday night into Monday...another low pressure system is progged
to drop southeast into the Plains. Within this upper trof...a
secondary upper low rounding the base of the trof is forecast
Wednesday before the trof finally exits the region Thursday. In
response...widespread showers and scattered thunderstorms are
forecast to spread back over the CWA starting Sunday night with
the peak of the precipitation being Tuesday. Precip chances look
to begin decreasing west to east during the day Wednesday and
finally tapering off Thursday with the departing upper level trof
axis. Limited severe potentials will be possible with this
activity Monday into Wednesday...though the greater impacts could
be from multiple rounds of locally heavy rainfall. Forecast
rainfall amounts Monday through Wednesday look to be widespread 3
to 5 inches across the CWA with the potential for locally higher
amounts. Continue to monitor forecast updates as the event nears
as amounts and locations are refined.
Across the CWA...temperatures behind the frontal boundary tonight
through Wednesday are forecast to be well below the seasonal
average with lows in the 40s and 50s and highs in the 60s to lower
70s! The coldest morning looks to be early Sunday morning as
cloud cover tries to scatter out across the north with lows in the
low/mid 40s to lower 50s north to south. Once the upper trof
exits Thursday...a ridge of high pressure looks to set up over the
region for next weekend which will help to return temperatures
back closer to the seasonal average. Drier conditions are also
forecast with the return of the ridge late next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Fri May 20 2022
Cold front located from approx KSNL-KTUL-KMIO currently and will
move little during the evening. Scattered storms are expected to
develop near the boundary around 00z, but evolution of this
activity remains very uncertain. More widespread showers and
storms with deteriorating flight conditions can be expected after
06z tonight north of the front, which will eventually push into
SE OK and NW AR Saturday and spread MVFR and periodic IFR
conditions into those areas by Saturday morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 60 63 47 68 / 60 50 20 10
FSM 71 82 54 68 / 40 70 60 20
MLC 68 76 50 68 / 50 50 30 10
BVO 56 60 44 67 / 60 40 10 10
FYV 67 77 48 66 / 50 70 60 10
BYV 66 76 48 64 / 50 70 60 10
MKO 64 69 49 67 / 60 50 30 10
MIO 58 61 46 65 / 70 70 30 10
F10 63 67 48 67 / 60 50 20 10
HHW 70 86 55 68 / 20 50 50 20
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18
LONG TERM....12
AVIATION...14