Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/30/20
Area Forecast Discussion
National Weather Service Amarillo TX
527 PM CDT Sun Mar 29 2020
.AVIATION...
VFR conditions expected through about 18Z with southerly winds 10
to 15 kts. After 18Z there will be a chance for showers and
thunderstorms for KGUY and KAMA. After 21Z for KDHT. Expect low
CIGs east of a line from roughly KGUY and KAMA. Winds west of this
line will have mainly a westerly component while winds east of
this line will have an easterly component by the end of the 00Z
TAF period ahead of a frontal boundary. Winds will start to
transition to the north behind a cold front towards the very end
of the TAF period for KDHT and KGUY first. LLWS will also be an
issue starting around 05Z for the northern Terminals, 10Z for
KAMA.
Hoffeditz
&&
.PREV DISCUSSION... /Issued 248 PM CDT Sun Mar 29 2020/
SHORT TERM...Today through Tomorrow Night...
Westerly winds aloft are bringing Pacific moisture across West Texas
with persistent high clouds over the forecast area all day today.
High temperatures will reach the mid to upper 60s, despite the
continuous cloud cover. The RAP shows the next shortwave pushing
onshore the western CONUS as it makes its way over the plains
tomorrow evening. Ascent ahead of the shortwave trough and a 50-60
knot jet with the left exit region over the Panhandles will provide
the dynamics for precipitation Monday. Meanwhile, a surface low will
form Monday morning in SE CO/NE NM and push southeast late Monday
afternoon along with the mid-level shortwave.
The chance for precipitation will begin in the eastern half of the
Panhandles during the mid-morning hours Monday as southerly winds
around 700mb begin to drive GoM moisture into Texas. Instability is
weak during this time with MUCAPE of about 500 J/kg present in the
eastern TX/OK Panhandles. The main show will be in the afternoon
hours, but this is contingent on how fast the clouds from the
morning precipitation can move out of the area and allow for daytime
heating. The areas of greater potential for storms to fire in the
afternoon are currently the west and central Panhandles along a
surface dryline. South winds will continue through the early
afternoon with a tongue of theta-e advection stretching across the
eastern Panhandles and dewpoints in the upper 40s to lower 50s.
Instability is better in the late afternoon and evening hours, with
MUCAPE values in excess of 1000 to 1500 J/kg and 0-6 km effective
bulk shear in the 60s as the overhead jet strengthens. Storms will
move east and out of the area by the late evening hours, but a few
storms may become severe before moving out as mid-level lapse rates
are around 7-8 C/km.
The CAMs have been picking up on the second round of initiation
across the central Panhandles. The NAM has not been as excited with
the second round of storms and has some initiation in the north, but
then is quick to die out with the lack of proper heating as it has a
cap overhead most of the day due to lingering cloud cover. Storms
that do form will be isolated in nature and mostly likely begin high-
based, but there is a chance for them to become surface based as
they move east as instability increases.
The Pacific front associated with the shortwave will push across the
forecast area late Monday evening as the chance for precipitation
will be cut off by 00z-03z and any storms that do fire will now have
moved into OK. A weak surface front will push south behind the
Pacific front with little effect to the temperatures Monday night.
Rutt
LONG TERM...
After the main H500 trough exits the region to the east early
Tuesday morning, zonal mid level flow will return to the region
through the first half of Thursday. Temperatures will remain
above average through Thursday with temperatures in the 70s with
some locations might reach the lower 80s. With a pronounced H250
140 kt southern stream zonal jet across south and west Texas, this
will set the stages for large scale upper level divergence and a
surface low to form over SW Kansas/northern combined Panhandles.
Latest 29/12Z model and numerical data does shows an associated
pseudo-dryline associated with surface low with some moisture
return out ahead. This could produce a chance of a shower or storm
for the far SE TX Panhandle ahead of the dryline where surface
moisture will try and work north from the Gulf of Mexico.
Otherwise, most areas will remain dry through mid week.
As we go thorough the day on Friday, a cold front will work south
from the central Plains, which will drop high temperatures back
to near or slightly below average. Going into Friday night and
early Saturday morning, a second mid level disturbance in the wake
of the cold front will work east across the central rockies into
the central Plains. With temperatures dropping by Friday night
into the upper 20s and lower 30s for parts of the northern
Panhandles, some local lift from the disturbance to the north may
produce light rain or rain/snow showers with no snow accumulations
expected at this time. H500 NW flow will return to the Panhandles
with dry conditions to end the long term forecast period.
Meccariello
FIRE WEATHER...
Elevated to near critical fire weather conditions are expected in
the far southwest Texas Panhandle Monday. 15 foot winds along the
Pacific front will range from 15 to 25 knots with gusts up to 35
knots possible. Winds will be out the south in the morning hours and
then begin to shift clockwise towards a northerly wind by the
afternoon and into the evening. A dryline setup will leave dry
conditions in the west with minimum relative humidity values in the
mid-teens. With the lack of precipitation, fuels have been near the
50th percentile and RFTI values are forecasted to be around 3-4.
Rutt
&&
.AMA Watches/Warnings/Advisories...
TX...Fire Weather Watch from Monday afternoon through Monday evening
for the following zones: Deaf Smith.
OK...None.
&&
$$
36/11
Area Forecast Discussion
National Weather Service Denver/Boulder CO
832 PM MDT Sun Mar 29 2020
.UPDATE...
Issued at 823 PM MDT Sun Mar 29 2020
Most of the showers moving off the foothills this evening appear
to be more virga vs actual showers so backed off the pops this
evening along the urban corridor, and kept most of the activity
near the foothills. Also made some adjustments to sky grids based
off the satellite.
&&
.SHORT TERM...(This evening through Monday)
Issued at 318 PM MDT Sun Mar 29 2020
Satellite imagery and radar data from the western slope are
showing increasing clouds and shower activity over the last couple
hours. The trough axis remains well to the west, indicating that
it will take until tomorrow afternoon for the main trough to pass
east of the state. Snow will gradually increase in the mountains
overnight with only light snow amounts. Shower activity on the
plains should be very minimal tonight.
For tomorrow, high resolution models continue showing shower
activity over the mountains and plains, mainly in the afternoon.
The RAP shows the main convective activity will be a bit further
to the east, and possibly entirely east of our forecast area.
Since it is late in the month, and Spring is springing, enough
daytime heating and instability will be present for some embedded
thunderstorm activity over the mountains and precipitation on the
far northeast plains to be entirely from thunderstorms. There are
indications that the I-25 corridor may only see virga from the
passing shower activity, with very little measurable
precipitation. That would open the door for some gusty winds near
the showers. Temperatures will be similar to this afternoon`s
values, primarily because of increasing amounts of clouds through
the day.
.LONG TERM...(Monday night through Sunday)
Issued at 318 PM MDT Sun Mar 29 2020
An upper level trough will exit the region Mon night, with any
leftover precip, ending in the early evening hours. Cross-
sections show gusty winds developing, in and near the foothills,
overnight into Tue morning with speeds just below hi wind
criteria. For the rest of the day, it looks mainly dry except for
a chc of showers over the far nrn mtns. Meanwhile, will see
warmer temps, as downslope westerly flow occurs, with readings in
the 60`s over nern CO.
For Tue night into Wed, a broad upper level trough will extend from
the nwrn US into the nrn Rockies, with west to southwest flow
aloft, across the area. There will be some moisture embedded in
the flow, which will bring a chc of showers to the nrn mtns.
Across nern CO, there are some differences as to whether a weak
front affects the plains on Wed. The GFS has this feature moving
into the area, while the ECMWF keeps it further north. As a
result, the ECMWF has temps in the upper 60`s to mid 70`s over
nern CO while the GFS has readings in the upper 50s to mid 60`s.
By Wed night into Thu, a piece of energy will move across Wyoming
with nrn CO on the srn fringe of this feature. In addition, a
cold front will move across nern CO as well. As a result, will
see a good of chc of snow in the nrn mtns, with a chc of showers
over nern CO. Highs will drop into the lower to mid 50s across the
plains.
For Thu night a second surge of colder air will move into nrn CO as
a weak disturbance affects the area. Thus, this will lead to a
chc of snow in the mtns, and possibly at lower elevators as well.
On Fri, drier air in westerly flow aloft, will move into the area
with decreasing precipitation chances. Temperatures will remain
below normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 823 PM MDT Sun Mar 29 2020
Easterly winds this evening should gradually transition to a
weaker southerly drainage overnight. Dropped the vcsh from the
terminals this evening as it appeared to be more virga vs actual
showers. Expect primarily VFR conditions. Minimal aviation impacts
expected again on Monday, but a few afternoon showers will be
possible after 2 PM, as a weather system moves out of the
mountains.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Dankers
LONG TERM...RPK
AVIATION...Cooper
Area Forecast Discussion
National Weather Service Boston/Norton MA
802 PM EDT Sun Mar 29 2020
.SYNOPSIS...
Pattern not changing much tonight into Monday as a secondary low
pressure lingers just east of Cape Cod and Nantucket. This will
lock in the clouds and continue a risk for showers or drizzle.
This low pressure should finally depart Monday night into
Tuesday. Variable cloudiness and seasonably cooler weather for
Tuesday into Wednesday. Though a midweek coastal low is looking
more likely to stay away from Southern New England, wrap-around
moisture from it will bring increasing clouds and periods of
showers by late week. Moderating temperatures for the weekend,
with the next cold front either late Saturday or Sunday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
730 PM Update:
Feeling the effects of increasing upper-level support from the
approaching trough, and in conjunction with elevated instability
(mid-level lapse rates around 6-6.5 C/km producing a narrow
ribbon of MUCAPEs < 500 J/kg), heavy showers and thunderstorms
have again blossomed over the Berkshires into the Pioneer Valley
and into northern Worcester County. These showers and storms
are rooted above chilly and very stable low-levels, moving to
the northeast at a fairly fast clip (60 mph). Given the elevated
weak instability, generally expecting these storms to mainly
produce occasional lightning and heavy rains, though in a
worst-case stronger cell, small hail between pea to half-inch
size would be possible. The stable low-levels should mitigate
how much wind is transported to the surface. Severe weather
isn`t expected, but the thunder could certainly startle some
people.
Did re-shape PoPs/Wx to bring isolated thunder mention at least
across a good part of western and central MA. Poor consistency
in the high-res CAMs makes for less confidence on if any storms
make it into the Boston-Providence corridor. At the moment,
appears the recent HRRR has the best handle on current activity,
with any thunder through midnight being north of the Mass Pike.
May need some adjustments to PoPs/Wx later, though did include
areas of drizzle/fog for the after-midnight portion of the
forecast.
No changes to temps which will not change much.
Previous discussion follows...
Secondary low pressure lingers east of Cape Cod and Nantucket
tonight. Expecting a lingering risk for showers or drizzle at
just about any time through this evening. Drier air moves in
aloft after midnight, ending most of the precipitation towards
CT and portions of the CT River Valley in MA.
Plenty of clouds sticking around, should mean temperatures
should not fall far. Still thinking above normal low
temperatures for the last day of March.
Some stronger showers/possible thunderstorms across the coastal
waters late this afternoon. Thinking this is about as far north
as any convection will get. Lapse rates are just too poor
farther north. In any case, any instability we do have will move
well off to the east by this evening.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As the secondary low pressure gets a bit stronger and moves
slightly farther offshore, expecting winds to turn more
northerly. It will be a subtle, but important, detail. Winds a
shade more from the northeast are much more likely to lock in
low clouds and drizzle, while a shift of only 20 degrees more to
the north will permit some drying in the lower levels, meaning
less drizzle.
A decent cold pool moves over the Great Lakes tomorrow, which is
close enough to generate a diurnal shower risk, especially if
some breaks of sunshine can develop. As this cold pool moves
farther east later in the day into Monday night, could see some
wet snow develop across the higher terrain of the interior.
Little to no snow accumulation expected.
Expecting high temperatures Monday to be similar to today,
before colder air arrives Monday night. Near normal low
temperatures for Tuesday morning.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...
* Cloudy and cooler than normal weather Tuesday into Wednesday.
* Monitoring track of a coastal low later Tuesday into Wednesday
night, though a direct impact is looking less likely. Better
chance for wrap-around showers central and eastern/coastal MA into
RI Thursday into Friday.
* Moderating temperatures by the weekend, though a cold front brings
a related threat for showers either Saturday or Sunday.
Details...
Tuesday:
Upper-level low will pull away into the waters south of Nova
Scotia on Tuesday. Pressure gradient between an offshore weak
cyclone and a high pressure wedge will continue to support a
cool onshore NE component, with winds at times across the outer
eastern/southeast waters gusting to near gale force at times.
Coverage of showers should dwindle into the afternoon as surface
ridge wedges southeast, with modest cool advection. All in all,
still a fairly unsettled day with a considerable amt of clouds
and highs in the low to mid 40s, coolest near the eastern MA
coast.
Tuesday Night through Wednesday Night:
Due to increasingly blocked mid/upper flow evolving over the
North Atlantic, the upper-level low over the Canadian Maritimes
retrogrades back across New England Tuesday night. Meanwhile, a
southern-stream trough over the central Appalachians and related
surface low will shift off the Carolina coast early Tuesday
night. This coastal storm remains progged to stay well south of
40 deg N latitude with little if any northward jog following
good consistency in the deterministic and ensemble guidance
across several model cycles. Given this, and now that the
southern-stream disturbance is entering the West Coast as of
this writing (and is becoming better sampled by the radiosonde
network), it appears less likely that Southern New England will
see any impact from this system. Have decreased PoPs to below
mentionable levels/dry forecast. Will be some wrap-around
moisture on an inverted trough that will affect our area
Thursday into Friday, however (to be described below).
So for Tuesday night through Wednesday night, while the pattern
is trending drier, expect a continued cooler than normal period
with still a fair amount of clouds as the retrograding upper low
and its cool pocket of air re-establishes itself. Highs on
Wednesday into the 40s (a spot 50 possible in the CT Valley into
Tolland County), coolest near the coast. Lows mainly in the 30s
each night, though may dip below freezing in northern MA.
Thursday into Friday Night:
12z guidance now indicates the best chance for any showers is
toward the latter part of the week, as an inverted trough trails
back across ME into Thursday, and shifts/builds southward
towards Southern New England later Thursday into Friday. Expect
a renewed increase in clouds areawide, and while some threat for
showers exists for many, the better chances are mainly across
east-central MA/northern RI eastward. Sided toward solid Chance
PoPs for the MA coastal plain eastward into the coastal waters,
with limited/slight chance shown further west into western MA
and northern CT.
Biggest source of uncertainty is regarding how quickly will the
inverted trough and related showers pivot SE and exit Southern
New England. The 12z ECMWF clears us out by Friday afternoon,
whereas the Canadian GEM and the GFS maintain lingering showers
even into Friday night. Did start to trend PoPs downward into
Friday night but with the blocky pattern upstream and at least
leftover troughiness hanging around into Friday night,
maintaining at least a slight chance shower mention.
Showed highs in the upper 40s to mid 50s Thursday, closer to
normal for this time of year. However, depending on how quickly
clouds/showers advance in on Thursday, it is possible that these
may be a bit too warm and may need to be lowered by a few
degrees. Similar highs for Friday. Lows each night in the mid
30s to lower 40s.
Saturday into Sunday:
Pattern starts to moderate into the weekend, with gradually
warming temperatures and shortwave ridging aloft supporting
less cloudy conditions.
Model guidance differs on when a cold front moves eastward
across our area. GFS and the Canadian are most progressive
(later Saturday) while the ECMWF is more into Sunday. Ensemble
means tend to support a later arrival, though will stick with
a general blend of models for this period.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update:
Tonight...Moderate to high confidence.
IFR to LIFR conditions to continue through much of the
overnight. Radar and near-term guidance indicate rumbles of
thunder mainly N/W of ORH/BED thru about 05z, moving quickly NE.
Low confidence on if these, or any additional storms make it
into eastern MA into RI and the South Shore. Will likely TEMPO
any imminent thunder threat, main threat would be occasional
lightning and brief downpours. Winds to become E and NE aroud
3-6 kt in the interior, but around 10-15 kt eastern MA and the
coast.
Monday and Monday Night...High confidence in trends. Moderate
confidence in timing.
Mainly low-end MVFR with areas of IFR conditions. Scattered
-SHRA at times. Chance for -SHSN across the higher terrain
Monday evening into Monday night.
KBOS Terminal...High confidence in the TAF trends.
KBDL Terminal...High confidence in the TAF trends.
Outlook /Tuesday through Friday/...
Tuesday: Mainly VFR, with areas MVFR possible. Windy with local
gusts up to 30 kt. Slight chance SHRA.
Tuesday Night: Mainly VFR, with local MVFR possible. Breezy.
Wednesday: VFR. Breezy.
Wednesday Night through Thursday: Mainly VFR, with local MVFR
possible. Breezy. Slight chance SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.
Friday: Mainly VFR, with local IFR possible. Breezy. Slight
chance SHRA.
&&
.MARINE...
Easterly winds diminishing tonight and shifting toward the
north/northeast tonight. Still expect heightened seas across the
ocean through Monday with rain and fog at times. Winds increase
once more as colder air arrive late Monday into Monday night.
Extended the Small Craft Advisories across the outer coastal
waters, where rough seas should linger into Tuesday. Elsewhere
across the coast waters, did not change much with respect to
previous timing. Did cancel the advisories for Boston Harbor and
Narragansett Bay, where wind gusts up to 20 kt are expected this
evening.
Outlook /Tuesday through Friday/...
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 12 ft. Slight chance of
rain showers.
Tuesday Night: Winds less than 25 kt. Areas of rough seas.
Slight chance of rain showers.
Wednesday: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers.
Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers.
Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas. Chance of rain showers.
Thursday Night through Friday: Low risk for Small Craft
Advisory winds with gusts up to 25 kt. Areas of rough seas.
Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ231-232.
Small Craft Advisory until 10 PM EDT this evening for ANZ233-
234.
Small Craft Advisory until 8 AM EDT Monday for ANZ235-237.
Small Craft Advisory until 8 PM EDT Tuesday for ANZ250-251-
254>256.
&&
$$
SYNOPSIS...Belk/Loconto
NEAR TERM...Belk/Loconto
SHORT TERM...Belk
LONG TERM...Loconto
AVIATION...Belk/Loconto
MARINE...Belk/Loconto
Area Forecast Discussion
National Weather Service North Platte NE
627 PM CDT Sun Mar 29 2020
.SHORT TERM...(This evening through Monday night)
Issued at 259 PM CDT Sun Mar 29 2020
A storm system over central California this afternoon will move
east and spread rain into parts of wrn and ncntl Nebraska Monday.
1/4 to 1/2 inch of rain is expected in many areas.
A fairly strong 700mb warm front should lift north through the
central high Plains tonight and precipitable water rises to over 1/2
inch Monday morning. The RAP model shows a 500mb wind speed max
aiding the warm front and this will likely be part of the forcing
for rainfall. Rain cooled sfc high pressure providing isentropic
lift just off the sfc might help support the longevity of the rain.
The models indicate once winds at 500mb decrease Monday evening, the
rain should end.
The SREF and HREF are close with the evolution of the rain spreading
north late tonight and Monday. The rain forecast Monday uses the
short term model blend for likely to definite rain chances across
much of western and north central Nebraska. The SREF is also giving
a fog signal across the wrn Sandhills early Tuesday morning. This
area will see partial clearing Monday night presenting the
opportunity for radiation fog.
The temperature forecast tonight through Monday night leans on the
short term model blend plus bias correction. This dataset marks up
lows tonight and Monday night and marks down highs Monday. The south
winds tonight, rain Monday, and extensive cloud cover Monday night
should support a narrower diurnal temperature swing relative to the
guidance blend.
.LONG TERM...(Tuesday through Sunday)
Issued at 259 PM CDT Sun Mar 29 2020
Today`s model runs indicate an upper low will form across western
Canada and remain nearly stationary next week. Disturbances
emanating from the upper low will move east through the nrn plains
and drive cold fronts through wrn and ncntl Nebraska. The fronts
will tap into 1065 mb arctic high pressure across nrn Canada north
of Hudson Bay. Cold air will begin spilling into wrn and ncntl
Nebraska Wednesday and continue through Friday. Cold south winds
develop around high pressure centered over the upper Midwest
Saturday producing a modest rebound in temperatures.
The best chances for rain or snow are Wednesday night and Thursday
night. WPC suggested a 10 to 30 percent chance of significant
weather weather across nrn Nebraska during these times. The event
Wednesday night is prefrontal while the event Thursday night is post-
frontal which might represent the better chance winter weather.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 627 PM CDT Sun Mar 29 2020
VFR will continue through early Monday morning for all terminals.
Cloud cover increases and cigs begin to drop around sunrise, then
precipitation spreads from southwest Nebraska into the Sandhills
during the day. MVFR cigs are likely in the afternoon, along with
intermittent visby drops and gusty southeast winds.
&&
.HYDROLOGY...
Issued at 259 PM CDT Sun Mar 29 2020
River levels on the Elkhorn river near Atkinson are being monitored
for possible flooding.
The Elkhorn river gage near Atkinson is on the rise and above action
stage this afternoon. Additional rises are expected and minor
flooding may develop in this area Monday. The MBRFC forecast
suggests a crest near 7.3 feet Monday evening. Flood stage is 7.5
feet. The rainfall Monday could produce additional rises on the
river Tuesday which could cause the river to rise to 7.5 feet.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
HYDROLOGY...CDC