Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/20/24
Area Forecast Discussion
National Weather Service North Platte NE
647 PM CDT Fri Apr 19 2024
.KEY MESSAGES...
- Light snow is likely south and west of North Platte tonight
and Saturday. No travel impacts are expected.
- The next significant storm system could affect wrn/ncntl
Nebraska Thursday and Friday next week. The potential for
strong or severe thunderstorms is uncertain.
&&
.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 312 PM CDT Fri Apr 19 2024
The forecast tonight through Saturday night revolves around the fate
of an upper level disturbance moving through Colorado. The latest
guidance suggests measureable rain and snow will remain mostly south
and west of North Platte. The dry air associated a late season high
pressure system from Canada should delay low level saturation in
many areas east of Ogallala until Saturday afternoon. By then the
best forcing or dynamics will be moving through KS, away from swrn
Nebraska. So, the moisture will be in place for precipitation
Saturday afternoon, but the forcing will be too weak for much more
than sprinkles or flurries.
The POP and QPF forecast leans on the HREF, or high resolution
ensemble forecast. This forecast generated an inch or less snow
across parts of the srn Panhandle and swrn Nebraska.
The temperature forecast leans on the the short term model blend,
the HRRR and RAP models which were warmer tonight than the NBM in
many areas, and cooler in many areas Saturday. The reason for this
is cloud cover which will block radiational cooling tonight and
solar insolation Saturday across most areas along and south of
highway 2.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 312 PM CDT Fri Apr 19 2024
Late season high pressure from Canada will build south and be
located over TX/OK/KS/MO by Sunday afternoon. In response to sfc low
pressure developing over wrn Canada, a warm front should push east
into wrn Nebraska.
There is not much change in the temperature forecast Sunday through
Tuesday; highs in the 50s and 60s Sunday warm into the 60s and 70s
Monday followed by a weak Pacific cold front Tuesday. Cool air will
back into Wednesday.
The main weather system next week will affect wrn and ncntl Nebraska
Thursday and Friday. The sfc low isn`t particularly deep near 993 mb
but the attendant warm front could provide excellent focus for
thunderstorms across ncntl Nebraska Thursday aftn/evening or perhaps
earlier. It is too early too speculate on the severe threat but
moisture, focus and shear will be in place. If the model timing is
correct, wrn and ncntl Nebraska will be post-frontal Friday. POPs
for this event are 40-60 percent which could be too high west of
highway 83 where somewhat drier air will be in place. The drier,
slower ECM shows a strong cap ahead of the upper low, while the
faster, wetter GFS has weakened the cap ahead of the dynamics.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 633 PM CDT Fri Apr 19 2024
Mostly VFR conditions will prevail across western and north
central Nebraska through Saturday. The exception will be across
southwest Nebraska to the south of I-80...where MVFR and some
light precipitation will be possible late tonight into Saturday
morning. Winds will be light, generally less than 15 kts.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Taylor
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1001 PM EDT Fri Apr 19 2024
...New UPDATE...
.UPDATE...
Issued at 953 PM EDT Fri Apr 19 2024
Cold front was moving into the mountains of east Tennessee late
this evening. As projected by various runs of a few different CAM
models, additional showers have popped up in the higher terrain as
a result of the front moving into these areas. Believe we still
have a few hours left of these scattered showers, but expect all
precip to clear to the east of the CWA well before daybreak. No
other changes appear necessary.
&&
.SHORT TERM...
(This evening through Saturday)
Issued at 245 PM EDT Fri Apr 19 2024
Key Messages:
1. Scattered showers and storms will continue into the early evening
hours with some possibly becoming strong to severe, mainly along and
east of I-75. Damaging winds and hail in excess of 1 inch in
diameter are the main concerns.
2. After the storms, cooler conditions will return with overnight
lows in the 50s and highs on Saturday remaining in the 60s for most
areas.
This Evening/Tonight
Currently this afternoon, fairly zonal flow is in place aloft with a
broad jet of over 100 kts north of Tennessee through the Great Lakes
region. A surface cold front is currently moving onto the Cumberland
Plateau. Ahead of the front, scattered convection has developed
across northern and eastern portions of the area with additional
development expected as the front advances eastward. The environment
consists of 500 to 1,000 J/kg of MLCAPE with fairly uni-directional
effective shear of 35 to 45 kts. Luckily, the overall forcing is
limited, in addition to very weak shear in the lower levels, keeping
the threat as damaging winds and hail. Places further north will
continue to be in the higher end of the shear magnitude due to upper-
level flow with places further south expected to see DCAPE values
closer to 800 J/kg or more. Area-wide, there is notable (>600 J/kg)
CAPE in the -10 to -30 region with WBZ heights only around 10,000.
This will allow for some melting of hail before it reaches the
ground with RAP data suggesting 50 dBZ reflectivity values around
25,000 feet AGL sufficient for 1-inch hail. These values are lower
in southwest Virginia. While shear is certainly sufficient for more
organized or even supercell structures, the environment is limited
by the overall forcing. Overnight, the front will move through the
area with lingering showers and storms diminishing west to east
around sunset. Winds will shift to a more northerly direction,
allowing for seasonally cooler conditions compared to last night.
Saturday
By Saturday, the cold front will have pushed off to our south with
high pressure expanding from the northwest. Increasing subsidence
and northerly flow will allow for low-level moisture to exit the
area, promoting mostly sunny and mild conditions. This will also
support efficient mixing and a drop in RH`s to near or below 30
percent across most of the area. Thankfully, a lot of vegetation has
returned, and low-level flow is expected to be fairly light.
&&
.LONG TERM...
(Saturday night through next Friday)
Issued at 245 PM EDT Fri Apr 19 2024
Key Messages:
1. Low chance of rain, mainly across our southern areas, on Saturday
night and Sunday morning associated with a surface low to our south.
2. High pressure arrives early next week with cooler temperatures;
chance of frost across the higher elevations and plateau on Monday
morning.
3. A quick system will bring low chances of precipitation towards
the middle of next week with high pressure returning behind the cold
front.
Discussion:
Generally quiet weather is expected for most of the extended period
with limited impacts. As a surface low pressure system moves across
the Southeast CONUS, widespread cloud cover and rain chances are
expected Saturday night into Sunday. This will mainly impact our
southern areas with clearer sky conditions and drier weather
arriving Sunday evening into the overnight hours.
Cooler temperatures and light winds will result in opportunities for
patchy frost across the higher terrain and plateau areas on Sunday
night into Monday morning and again on Monday night into Tuesday
morning. At this time, limited impacts are anticipated. With the
cold surface high pressure airmass and Eastern CONUS troughing,
temperatures will be 5 to 10 degrees below normal early next week.
Ridging begins to build back in on Tuesday with a low pressure
system moving quickly across the Great Lakes region. This will bring
another cold front across our region on Wednesday. However, with
high pressure and ridging across the Lower Mississippi Valley
limiting moisture advection northward across the Tennessee Valley
and Southern Appalachians, probabilities of precipitation remain low
with only light accumulation expected.
High pressure is forecast to return in the wake of the departing
cold front late next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 755 PM EDT Fri Apr 19 2024
All sites are currently VFR, but widespread MVFR CIGS are expected
to push into east Tennessee in the next 3-6 hours and last into
tomorrow morning. Low level moisture supporting MVFR CIGS is
fairly thin, so expect a return to VFR for all terminals by around
16z Sat morning after mixing gets underway. Otherwise, winds will
be light through the period, generally around 5kt or so out of the
north.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 81 57 69 50 / 50 10 10 40
Knoxville McGhee Tyson Airport, TN 81 54 67 48 / 80 10 10 20
Oak Ridge, TN 78 53 68 47 / 70 10 10 20
Tri Cities Airport, TN 76 51 65 43 / 80 30 10 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...CD
LONG TERM....JB
AVIATION...CD