Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/20
Area Forecast Discussion
National Weather Service Cheyenne WY
556 PM MDT Fri Apr 24 2020
.SHORT TERM...(This evening through Saturday)
Issued at 311 PM MDT Fri Apr 24 2020
Weather Impact Summary: Ongoing scattered showers and isolated
thunderstorms are occurring across High Plains of SE WY and NE
Panhandle. Some of the deeper showers and thunderstorms have
produced pea-sized hail and wind gusts of 40 mph. These stronger
isolated showers will continue through about 8pm and decrease in
coverage and intensity thereafter.
Weather Details: MLCAPE values near 300-600 J/KG and steep mid-
level lapse rates under embedded weak H7-H3 vorticity impulses is
supporting scattered to numerous shower and isolated thunderstorm
activity this afternoon. Instability will wane through the early
evening hours and overall coverage will slowly decrease through
the evening and overnight. Some light residual precipitation could
linger across the higher terrain through early Saturday morning
due to weak orographics but amounts will be light and no impacts
are expected.
For Saturday - slightly stronger ridging and warmer H7
temperatures will shift east across WY and NE. While some very
isolated showers will be possible along the southern Laramie
Mountains and foothills, much less coverage is expected tomorrow
vs. today given lower instability and slightly increased
subsidence. Saturday will start the warming trend into the back
half of the weekend and into next week.
.LONG TERM...(Sunday night through Thursday)
Issued at 300 AM MDT Fri Apr 24 2020
Long range models for next week continue to show a warmer and more
pleasant weather pattern across the Front Range with low chances for
precipitation until the end of the week. Northwest flow aloft this
weekend will become more westerly on Monday as a Pacific disturbance
aloft rapidly moves eastward embedded in the westerly flow. Outside
of some showers or thundershowers Monday and Monday night, this
system will have little impact over southeast Wyoming and western
Nebraska. All models then show a high amplitude upper level ridge
axis developing over the western third of the United States by
midweek, allowing 700mb temperatures to increase between 5c to 12c.
Expect daytime temperatures in the 70s for most of the week with a
brief cool down on Tuesday. Highs on Thursday may even reach the low
to mid 80s for the eastern plains, east of the Laramie Range, as the
upper level ridge axis nudges east of Front Range during the day.
Past Thursday, noting an increase in llvl instability and a greater
potential for afternoon/evening showers and thunderstorms under
southwest flow aloft later in the week. Started increasing POP
next Friday with models in pretty good agreement.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 553 PM MDT Fri Apr 24 2020
Showers and isolated weak/brief thunderstorms coming down the
northwesterly flow will gradually diminish through 03Z. Still some
potential (especially over the Nebraska Panhandle) of getting a
gust to near 40 kts out of some of this activity judging from the
boundary layer profiles, but chances of anything stronger right
now look to remain low. IC and CC lightning activity also dropping
gradually as well where currently noted in far eastern Wyoming
and the western Panhandle. Looks like a similar pattern tomorrow,
but as the HRRR and the NAM-Nest suggests less coverage with
midlevel temperatures warming up a bit as ridging works in from
the west. So, resultant forecast keeps all TAF locations in VFR
through the next 24 hours with the exception of Laramie where we
may get some fog and lower ceilings down to MVFR toward morning.
&&
.FIRE WEATHER...
Issued at 311 PM MDT Fri Apr 24 2020
No fire weather concerns today and next several days with non-critical
winds and humidity levels. Precipitation today will wane this evening
with a drier and warmer weekend ahead. Will need to keep watch of next
Tuesday and Wednesday for critical relative humidity levels but winds
should remain below 20-25 mph.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...JSA
LONG TERM...TJT
AVIATION...Garmon
FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1108 PM EDT Fri Apr 24 2020
.AVIATION...
High pressure with dry northerly flow has largely scattered out low
clouds tonight with VFR conditions expected to prevail through this
morning and afternoon. There will be some mid to high cloud streaming
over the region associated with various waves moving across the
plains and into the Midwest. Strengthening low pressure system to our
south will lift into the Ohio Valley bringing a low chance for light
rain showers during the afternoon for the southern terminals. Will
leave mention of showers out for now due to the amount of low level
dry air that is maintained across the area in the lowest 5kft that
may result in mostly virga. The best chance at any rain showers will
likely come in the evening with the closer approach of the low
pressure system and again confined to the southern terminals, which
still may hold to the south. Prolonged period of N-NE winds will
continue with a gradual increase in gust potential resulting from the
tightening pressure gradient during the evening as well.
DTW THRESHOLD PROBABILITIES...
* Low for ceiling below 5000 feet through this morning.
&&
.PREV DISCUSSION...
Issued at 343 PM EDT Fri Apr 24 2020
DISCUSSION...
Residual low level stability that developed from low level cold
advection in recent days has been perpetuated over Southeast
Michigan today with cold stable flow off of Lake Huron. Not much
synoptic scale forcing for surface anticyclone exists at this time
with upper level confluence having pushed eastward and straight
neutral flow trajectories through the lowest 10 kft agl. This is not
totally trivial as the cloud trends today have been a function of
the amount of lower tropospheric stability with trapped moisture
below inversion. The 24.12Z KDTX RAOB was a tell this morning with
high RH below 9.0 kft agl and deep saturation from the surface
through 2.5 kft agl. Surprising then to see the amount of clearing
that developed midday. The relatively dry RAP based soundings
support a cumulus response this afternoon with daytime heating and
increased insolation. Combination of high cloud and afternoon
cumulus on satellite holding firm with the sky fraction this
afternoon.
An extremely busy 500mb vorticity chart is in place over much of
North America. Suppressed geopotential heights exist over the
southern 1/2 of the contiguous United States with zonal flow
throughout much of the northern half of North America. What this has
led to is a weekend forecast period that has been difficult to
forecast for. The low predictability has arisen from the multitude
of shortwaves "advecting" through the flow and the models difficulty
in handling the phasing/separation of the shortwaves. As for the
sensible weather forecast for Southeast Michigan this weekend there
are a couple of features to key off of. The first is the secondary
jet streak set to develop directly overhead of Southeast Michigan
tonight. Recent model trends suggest that right entrance region
dynamics and associated frontogenetic/inverted trough response is
now farther to the south and southwest. The result of this is a less
progressive solution in lifting midlevel fgen into the cwa during
the day Saturday. The second item to key off of is the stout,
organized dry air feed that will remain directed at the area. Survey
of model soundings show less saturation and moisture in the lowest
10 kft agl, especially in the NAM soundings. For this issuance,
decided to go with broadbrush chance PoPs to account for midlevel
fgen, and likely virga activity south of I 69 late Saturday
afternoon
Model consensus exists that keeps northern sharp edge to deformation
forcing mainly south of Southeast Michigan Saturday night and
Sunday. NWP is showing a good signal for enhanced AVA dipole and
assoicated deep subsidence settling across Southeast Michigan.
Surface ridging is expected again with cold stable flow off of Lake
Huron which will result in relatively decent day. Questions still
exist on the amount of high cloud that will persist over the area,
but all in all a decent Spring days expected both Sunday and Monday.
The next chance for precipitation will come Monday night and Tuesday
as warm advection ramps up across the area. Difficult to project
coverage of precipitation at this time as area will largely be under
the influence of very strong anticyclonic flow.
MARINE...
Winds will gradually diminish this evening across the central Great
Lakes given an increasingly diffuse pressure field and stable
nocturnal low-levels. Dry conditions persist through the night with
rain chances steadily rising on Saturday as a plume of moisture
associated with a strengthening low pressure system lifts into the
lower Ohio Valley. Flow will hold in the northeast quadrant for most
of Saturday with speeds AOB 15 knots. Stronger winds are expected
late Saturday night and Sunday as the northwest corner of the
tighter pressure gradient clips the southern waterways as the low
tracks northeast. This will likely lead to a period of 25-30 knot
gusts and higher wave action until late Sunday night. Dry weather
Sunday afternoon will then continue through Monday night as high
pressure west of Lake Michigan briefly takes control.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....AA
DISCUSSION...CB
MARINE.......KK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
815 PM EDT Fri Apr 24 2020
.UPDATE...
Issued at 755 PM EDT FRI APR 24 2020
Hourly grids were updated based on recent observations and
satellite and model trends. Cumulus and stratocu linger across
the region with some cirrus passing overhead as well and sky cover
was increased a bit over the next couple of hours. Overall, no
substantial changes were needed at this time.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 430 PM EDT FRI APR 24 2020
Late this afternoon, an upper level trough is nearing the mid
Atlantic coast and continues to depart to the northeast. A pattern
of a broad trough from the central to eastern Conus is in place
with this trough being downstream of a ridge the axis of which is
near the west coast of the Conus. Also moving within the upper
level trough was a shortwave over the Plains. At the surface, an
area of low pressure was centered over eastern OK with a warm
front extending into the Gulf of Mexico and a cold front trailing
into central TX. Locally weak high pressure between a departing
system and the system to the southwest was building into the
area. Low level moisture lingers with some breaks in the cumulus
and stratocumulus. A few sprinkles were still occurring from Pike
County southwest to Harlan County.
This evening and tonight, some further clearing is expected and
window of mostly clear skies may be experienced across portions of
the area by late evening into the start of the overnight. As the
low level flow becomes northeast to east the clearing may slow in
the Big Sandy region or clouds might advect back in. Winds are
expected to slacken overnight and where skies can clear fog may
form in valleys considering the recent wet weather. Patchy fog or
even areas of valley fog were used to cover this. Clouds will
increase later tonight as the next system approaches and this may
tend to lead to the valley fog dissipating toward sunrise. Valley
locations should experience lows in the mid 40s with upper 40s
expected elsewhere.
Clouds will thicken and lower further on Saturday as the low
pressure system and upper level trough move from the mid MS Valley
into the lower OH Valley. Models are rather consistent with
isentropic lift/warm advection leading to one or more bands of
showers or an area of showers that moves across the southern
portions of the area late in the morning to midday and then into
the central and northern portions of the area from midday through
the afternoon. Behind the initial isentropic lift/warm air
advection band of showers, instability will increase as mid level
lapse rates approach or possibly exceed 7C/km near peak solar
insolation as the low tracks into central KY. Bulk layer shear of
30 to 40KT is forecast in the models with MUCAPE of about 1000 to
1500 J/KG in the west and south. This could set the stage for a
couple of clusters or discrete cells that could exhibit some
updraft rotation and produce hail, gusty winds, and or brief
heavy rain. HREF probabilities point toward locations near the TN
border over to the KY/TN/VA tri state area having the greatest
chance for a stronger storm or two. Convective allowing models
from 18Z such as the NAMMEST and HRRR have a few updraft helicity
swaths extending into mainly the southern counties. The 12Z HREF
UH probs are generally greatest near the TN border. If enough
instability is realized, an isolated severe thunderstorm or two
may occur late in the afternoon or early in the evening.
The surface low should move slowly to the mid OH Valley through
around dawn on Sunday with the upper level trough axis moving into
the area on Saturday night. Even after the threat for
thunderstorms diminishes with lessing instability on Saturday
evening, cooling aloft will lead to the continued threat of rain
showers for Saturday night.
Another wetting and soaking rain is expected with this system.
Around a half of an inch of rain is expected from Saturday into
Saturday night with additional showers early in the long term
period on Sunday.
.LONG TERM...(Sunday through Friday)
Issued at 240 PM EDT FRI APR 24 2020
The period begins with vertically stacked low pushing northeast
of Kentucky. We will see wrap around moisture leading to rain on
Sunday especially in northeast Kentucky, as this system departs to
the east. The guidance continues to lean toward dry weather
returning Monday, as high pressure and shortwave upper level
ridging briefly build in from the west.
Another more amplified wave progresses toward the area bringing
another shot of rain beginning Tuesday night, and the chances of
rain will go into Thursday as closed upper low pushes across the
Ohio Valley. The peak chances for showers and some thunderstorms
will be Wednesday, as a cold front is set to cross the Bluegrass
State. This could lead to a few strong storms under a strongly
sheared environment, but the MUCAPE looks more marginal right
now. However, the steeping mid level lapse rates may be able to
help the marginal CAPE. The timing of the front may also be a bit
quick for better building of instability. The GEFS CIPS analog
does have a signal in the area, but plenty enough uncertainty to
leave any mention out of the HWO for now.
Finally this amplified system will slowly push across the Ohio
Valley and this will keep cool rain going through Thursday into
Thursday night. Then yet another surface high pressure and more
amplified upper level ridge will push toward the Ohio Valley
Friday, but some left over isolated northwest flow showers remain
possible before this builds into eastern Kentucky.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 800 PM EDT FRI APR 24 2020
Mostly VFR was observed across the region with some localized IFR
or MVFR in the southeast portions of the area in the KSJS vicinity.
Weak high pressure will cross the area tonight, with another low
pressure system entering the OH Valley. Some stratocu redevelopment
may occur in the Big Sandy region near KSJS and some deeper river
valley fog generally not affecting the TAF sites. Otherwise, mid
level clouds should increase, thicken and lower from southwest to
northeast generally after 12Z with one or more bands of showers
spreading across the area. Some brief MVFR is possible as these
pass. Overall, mainly VFR is expected to remain until the end of
the period at the TAF sites, but MVFR should move into the
northwest near KSYM late. Isolated thunder is also possible after
18Z, but confidence and coverage is not great enough to include
at this time. Winds will average northeast through 0Z at less than
10KT, before becoming light and variable. East southeast to
southeast winds will increase between 12Z and 18Z into the 5 to
10KT range.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...JP
LONG TERM...DJ
AVIATION...JP
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1045 PM CDT Fri Apr 24 2020
...New AVIATION...
.SHORT TERM...
(This evening through Saturday)
Issued at 236 PM CDT Fri Apr 24 2020
An upper trough currently across the Central High Plains will be
digging into Oklahoma in the next few hours and through the evening
hours, providing the upper support for storms to begin firing up
soon across portions of northcentral into eastcentral Oklahoma.
Meanwhile, a surface low will continue to be pushed across southern
Oklahoma and into southeastern Oklahoma as the afternoon progresses,
while this systems breezy cold front nearly along the I-44 corridor
will continue to move through. So far, radar has been showing
scattered light rain showers near the front across northcentral
Oklahoma, with isolated storms just outside our CWA in Osage County.
Expecting more convection to develop further southward along the
surface boundary and become more linear in shape across portions of
eastcentral Oklahoma. Latest HRRR seems to have a good handle on
these storms, becoming more intense as develop across southeast
Oklahoma. As the surface low settles into southeast Oklahoma,
expecting the midlevel to cool and strongly destabilize, with
MUCAPE values approaching 3000 J/kg. Conditions will be favorable
for supercells to develop across portions of southeast Oklahoma
late in the afternoon as the surface boundary starts to move in,
with large hail and severe wind gusts as the main hazard.
Expecting this system to move through our far eastern CWA and
further into southeast Oklahoma by the evening hours.
Being on the back side of the cold front, tonight should be dry and
a little bit cooler and breezy as we tap into air originating from
the Central High Plains. Saturday will be dry and mild with
seasonably average temperatures.
&&
.LONG TERM...
(Saturday night through next Thursday)
Issued at 146 PM CDT Fri Apr 24 2020
Models continue to show WNW or NW upper flow for the region for much
of next week with a trough digging into the eastern U.S. with an
upper low in the Great Lakes/Ohio Valley area. Models then show the
upper ridge shifting east across the southern Plains late next week.
Models also show a cold front moving across the area Tuesday.
Disturbances moving through the WNW/NW flow could lead to off and on
shower and thunderstorm chances. The most likely or consistent time
frame for showers/storms has been Monday and Tuesday, especially on
Tuesday with the front moving across the area. Enough instability
could be around for some strong to severe storms to be possible.
Near or above average temperatures are expected Sunday through next
week.
&&
.AVIATION...
(06Z TAFS)
Issued at 1023 PM CDT Fri Apr 24 2020
VFR conditions expected. Mainly light to moderate northerly winds
will continue into tomorrow, with winds becoming light and
variable by end of forecast period. LLWS will be included from
KPNC down to KOKC/KOUN first part of forecast with strong
northerly flow just off the deck due to strong cyclogenesis over
Missouri.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 50 71 48 75 / 0 0 0 0
Hobart OK 47 73 47 78 / 0 0 0 0
Wichita Falls TX 49 75 48 80 / 0 0 0 0
Gage OK 44 71 45 79 / 0 0 0 0
Ponca City OK 49 70 44 75 / 0 0 0 0
Durant OK 52 73 50 77 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...03
LONG TERM....68
AVIATION...11