Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/20
Area Forecast Discussion
National Weather Service Bismarck ND
906 PM CDT Mon May 18 2020
.UPDATE...
Issued at 854 PM CDT Mon May 18 2020
Will allow the Wind Advisory to expire. Winds at Williston have
diminished to around 20 mph with gusts to 35 mph (below advisory
criteria) at 9 PM CST and are the strongest in western ND this
hour. It will remain breezy through the night across western and
central ND, but winds will remain below advisory criteria.
We bumped up sky cover a little, otherwise no significant changes
for the late evening update.
UPDATE Issued at 639 PM CDT Mon May 18 2020
Current forecast looks in line so only a few adjustments to sky
increase sky cover a bit with thicker cirrus moving over the
forecast area. A strong pressure gradient remains over the west
and is pushing into the central. The current advisory in the west
runs through 8 PM MDT and that looks reasonable. Winds from the
Highway 83 corridor west to the current advisory are right near
advisory criteria, but we expect these winds to diminish here
shortly. Everyone will see breezy winds overnight, but below
advisory criteria.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 251 PM CDT Mon May 18 2020
Warm and breezy conditions are expected on Tuesday with highs
nearing 90 degrees F in the west/southwest. There is a very slight
chance of thunderstorms in the far west Tuesday evening, with the
potential for severe hail if one does form.
Aloft, a deep trough was situated over the western US coast with 50
kt 500mb flow extending from the Great Basin through the Northern
Rockies. A ridge was parked over the central High Plains through the
Upper Mississippi Valley upstream of a closed low centered over
Illinois. At the surface a strong pressure gradient was draped north-
south through the western Dakotas as pressure falls were ongoing in
eastern Montana. Within this surface pressure gradient, southerly
winds gusting to around 50 mph were reported this afternoon in far
western North Dakota.
Though diminished somewhat, breezy winds will continue overnight
tonight and tomorrow as the pressure gradient slowly shifts east.
Low-mid level flow will be slightly so surface winds shouldn`t be as
strong, but still in the 20 to near 30 mph range Tuesday afternoon.
Very warm low level temperatures begin to move over the area as well
with MOS guidance consistent in producing surface temperatures in
the upper 80s to near 90 in the far west. 70s to low 80s can be
expected elsewhere.
Tuesday afternoon and evening, ongoing southerly low level flow is
expected to advect dew points in the 50s to around 60 in the
southwest/west portions of the state. Coincident with the warming
850-700mb air mass and the development of a potent elevated mixed
layer, a capped atmosphere with increasing MUCAPE will be in place
by Tuesday evening. Though the 12Z GFS/NAM produce a subtle impulse
out of the main trough in the evening, there is little evidence in
forecast soundings of enough low to mid level moistening to overcome
the capping inversion. On the conditional potential that a
thunderstorm does form Tuesday evening, lapse rates and deep layer
flow may be enough to produce a severe hail threat.
.LONG TERM...(Wednesday through Monday)
Issued at 251 PM CDT Mon May 18 2020
Chances for showers and thunderstorms increase Wednesday
afternoon/evening in far western North Dakota with a potential
for severe weather and heavy rainfall. Generally the best chances
for thunderstorms will be further west into Montana. Almost daily
chances for showers and thunderstorm fill out the rest of the long
term forecast.
Wednesday, the main trough is forecast to track northeastward out of
the Intermountain West and the Northern Rockies. In response,
surface cyclogenesis will occur over eastern Montana, Wyoming, and
the western Dakotas. With a continued poleward flux of boundary
layer moisture expected along the surface trough and ongoing mid-
level lapse rate advection, a corridor of 1000-2000 J/kg of MLCAPE
is expected to develop Wednesday afternoon. Greatest instability and
forcing for ascent should be focused generally along and in the near-
vicinity of the surface trough axis and frontal boundary, making the
potential of severe convection in North Dakota uncertain as 12Z
guidance keeps the surface trough axis in eastern Montana through
most of the night. Additionally, deep layer shear will be in
question with the 12Z GFS/ECMWF producing only 25-35 kts of
effective bulk shear along our west as the bulk of the better mid-
level flow should be kept further west. In either scenario, mostly
unidirectional southerly flow along the frontal boundary should
promote upscale growth or messy convective modes Wednesday
evening...further decreasing confidence in a more widespread
severe potential. At the time it looks as if the the greatest
severe potential will be for the very far west portions of the
state on the condition of initially discrete storms in a modest
but adequate supercell environment. This applies as well to the
general eastward extent of precipitation in the forecast with best
chances kept to the west. Lastly, there will be the additional
threat of very heavy rainfall with these potential thunderstorms
given anomalously high precipitable water values in the west
shown on NAEFS guidance (in the 90th to near climatological max).
Another shortwave enters the broad trough from the northwest coast
on Thursday, keeping a mean troughing pattern over the
west/northwest CONUS through the rest of the week. Embedded
perturbations in southwest flow over the Northern Plains keeps
persistent daily chances for showers/thunderstorms for the remainder
of the forecast period with somewhat cooler but seasonable
temperatures expected.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 854 PM CDT Mon May 18 2020
LLWS was added to KMOT and KBIS around the 06-12 UTC timeframe.
Otherwise VFR conditions expected through the forecast period
with only mid and high clouds and a moderate to strong southeast
flow.
00Z RAP soundings continue to indicate winds around 50 knots at
Minot and Bismarck after midnight. No changes to current TAFs.
Previous Discussion...
The 19 May 00 UTC Bismarck sounding indicates strong southeast
flow aloft. This seems to match up better with the current RAP
guidance better than the NAM or GFS. The latest RAP forecast
soundings show winds aloft increase tonight to around 50 knots
out of the south southeast at Bismarck and Minot after midnight.
Even though surface winds are nearly the same direction, this
still gives 30 to 40 knots of shear. We did allow for surface
winds to drop off to around 15 knots. If surface winds do not drop
off, we probably won`t have enough shear, just some turbulence
through 2000 ft. Will continue to monitor this evening for the 06Z
TAFS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...AE
LONG TERM...AE
AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
812 PM MDT Mon May 18 2020
.UPDATE...
Issued at 812 PM MDT Mon May 18 2020
Some cumulus congestus clouds formed to the southwest of Denver
early this evening. Radar didn`t pick up much for echos. This
likely had a little virga and localized gusty winds. The activity
will decrease in the next couple hours. Gusty southeast winds to
40 mph are expected to linger through the evening and then
decrease across the eastern plains. Enough wind should prevail
overnight to produce mild overnight lows. Made a few tweaks to
winds and sky coverage to line up with current conditions,
otherwise no other changes were made to the forecast.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 328 PM MDT Mon May 18 2020
Temperatures have warmed quickly this afternoon with DIA reaching
88 by 245pm. The HRRR still produces showers over the Denver
metro this evening but considering the lack of almost any cloud
development over the mountains and foothills this afternoon, I
doubt those showers will occur. Therefore, PoPs were kept below
10 percent this evening.
Tonight, there could be some hazy conditions as moisture creeps in
from the east but fog is not expected to develop. Some low clouds
are possible mainly across the far eastern plains closer to
Kansas and Nebraska.
A large trough continues pushing eastward toward Colorado on
Tuesday although the strongest mid to upper level winds will not
enter the state until Wednesday. With 700 mb temperatures
approaching 16-17 degrees C, high temperatures will race toward
90 degrees F over the Denver metro and the South Platte River
Valley. Current, the forecast is 89 at DIA as the presence of
cloud cover and scattered showers and storms may keep the
temperature down just a tad. However, the record high of 90
degrees in Denver could be tied or broken. High lapse rates with
near dry adiabatic temperatures to around 500 mb will lead to
high-based showers and storms developing in the afternoon.
Considering the inverted-V soundings all the way up to 500 mb,
these showers and storms will likely produce dry microbursts with
strong to severe wind gusts up to 60 mph. These showers and storms
could produce small hail which should remain below severe limits
across our forecast area. The only exception would be across the
northern half of Weld and Larimer Counties as better instability
will exist there. The dry and windy conditions will create
critical fire danger as well and that is discussed in the fire
weather section below.
.LONG TERM...(Tuesday night through Monday)
Issued at 328 PM MDT Mon May 18 2020
Warm and active weather will continue on Wednesday as a high
amplitude upper air pattern remains over the western United
States. Moderate southwesterly flow aloft will continue downstream
from an upper low over Idaho. At the surface, a low pressure
trough along the foothills will help to induce southeasterly low
level flow which will be drawing gulf moisture into the region.
Daytime heating and wind shear profiles should be sufficient for
strong afternoon thunderstorms to develop on the plains.
A weak cold front moving over the plains Thursday morning, in the
wake of Wednesday evening`s convection should be enough to reduce
the threat of thunderstorms as afternoon highs only reach the
lower 70s. Heading into the weekend, temperatures are expected to
warm again to slightly warmer than normal. Afternoon instability
each day should allow for widely scattered thunderstorm activity
to develop. The latter half of the weekend will be cooler again,
but medium range models show a variety of solutions for the
start of next week, so no more details can be given now.
Most precipitation over the next several days should be on the
plains, so it should have little impact in the ongoing melt-out of
the winter snowpack. Mountain streams will see increased flows,
but channels will have plenty of capacity to handle the flow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 812 PM MDT Mon May 18 2020
VFR conditions will continue through Tuesday. Winds will stay
more south to southeast compared to drainage tonight. Gusts to 30
knots will continue through 05Z before decreasing.
Elevated showers and storms will be more numerous tomorrow
afternoon. With inverted-V soundings that reach up to near 500mb,
these showers and storms will be capable of producing very strong
to potentially severe wind gusts. Ceilings and visibilities should
not be reduced much in these showers and storms. Expect this
convection to occur after 21Z Tuesday.
&&
.FIRE WEATHER...
Issued at 328 PM MDT Mon May 18 2020
Moderate to strong south-southwesterly flow will be over the
forecast area on Tuesday with surface wind gusts as high as 35-40
mph. Relative humidities will drop to the low teens across South
Park, the southern Front Range Foothills, the Palmer Divide, and
the Denver metro. This combination of dry and windy conditions
will lead to critical fire weather conditions across these areas.
In addition, showers and storms could create strong to severe wind
gusts up to 60 mph with very little rainfall which will increase
the fire danger further. Overall, these conditions are somewhat
marginal to issue a Red Flag Warning but the fact that a fire
started in the southern foothills today has lead me to issues one.
The Red Flag Warning will be in effect from noon to 8pm tomorrow for
South Park, the southern Front Range foothills, and the Palmer
Divide. A Red Flag Warning was not issued over the Denver metro
since fuels are in green-up and not conducive for rapid fire
growth.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Tuesday for COZ214-216-
241.
&&
$$
UPDATE...Meier
SHORT TERM...Danielson
LONG TERM...Dankers
AVIATION...Meier
FIRE WEATHER...Danielson
Area Forecast Discussion
National Weather Service Duluth MN
1048 PM CDT Mon May 18 2020
.SHORT TERM...(This evening through Tuesday night)
Issued at 249 PM CDT Mon May 18 2020
Windy conditions with critical fire weather across portions of
northeast Minnesota this afternoon and evening highlight the short
term forecast.
See the fire weather section below for details on critical fire
weather conditions that will continue for portions of northeast
Minnesota into early this evening. Strong northeast to easterly
winds across the Northland will continue into the early evening
north of deep low pressure across Illinois. Momentum transfer has
been very efficient thus far this afternoon from the Brainerd and
Walker areas northeast into the Twin Ports and the Iron Range with
peak gusts of 30-40kts. 17Z RAP soundings favor a very slow
decrease in the mixed layer momentum through the afternoon and
early evening, thus, peak gusts over 30kts are likely to continue
into the early evening.
On Tuesday, a surface ridge axis will support east to southeast
surface winds across the Northland favoring highs in the 50s and
60s near Lake Superior with onshore flow, and 70s elsewhere far
enough from the influence of the lake with plentiful sunshine.
.LONG TERM...(Wednesday through Monday)
Issued at 249 PM CDT Mon May 18 2020
A warming trend through the extended with chances for
thunderstorms late this week and into the weekend highlight the
extended forecast.
The 12 UTC global suite favors an upper level ridge building
across the central CONUS into mid week, transitioning to a high
over low blocking pattern, and eventual southwest flow aloft
across the Upper Midwest late this weekend and weekend. This all
favors a warming trend to widespread highs in the 70s, and maybe
a few 80s, this week with increasing chances for thunderstorms
Friday and into the weekend with impulses likely to be embedded in
southwest flow aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 655 PM CDT Mon May 18 2020
As high pressure moves into the region, mostly clear skies and
VFR conditions will continue this evening and into Tuesday. Winds
will be breezy at the surface this evening with LLWS about 2000
feet agl possible at HYR in the overnight hours. There is also a
chance for LLWS near DLH and BRD from midnight to 7 AM CDT;
however, there was quite a bit of variation between models of the wind
shear strength and timing. Thus decided not to add LLWS to DLH
and BRD yet and see how winds progress over this evening. High
pressure continues on Tuesday with VFR conditions and
west/northwesterly winds 10 to 15 knots with stronger winds near
DLH.
&&
.MARINE...
Issued at 1035 PM CDT Mon May 18 2020
Breezy conditions are again likely across western Lake Superior on
Tuesday before winds begin to decrease on Wednesday. As high
pressure continues to move into the region, winds and waves will
diminish overnight before increasing again early Tuesday morning.
Northeasterly winds 10 to 20 knots with gusts up to 25 knots, and
waves 3 to 5 feet will affect the North Shore from Grand Marais to
the Twin Ports, as well as the South Shore. A Small Craft
Advisory is in effect from 8 AM to 9 PM CDT on Tuesday. Depending
on how strong the winds get the Advisory might need to be extended
further towards Grand Portage Monday afternoon. By Wednesday,
winds begin to calm with northeasterly winds 5 to 10 knots.
&&
.FIRE WEATHER...
Issued at 249 PM CDT Mon May 18 2020
A Red Flag Warning remains in effect until 7 PM CDT from the
Walker and Brainerd areas northeast through the Iron Range of
central St. Louis county. Strong easterly winds sustained at 15 to
20 mph with gusts to near 30 mph at times, relative humidity of
20 to 25 percent, and high temperatures in the 70s will combine
with dry fuels to create critical fire weather conditions this
afternoon and early evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 43 61 44 69 / 0 0 0 0
INL 43 77 49 79 / 0 0 0 0
BRD 44 70 52 76 / 0 0 0 0
HYR 46 73 49 78 / 0 0 0 0
ASX 41 62 44 73 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from 8 AM to 9 PM CDT Tuesday for LSZ121-
141>148.
&&
$$
SHORT TERM...PA
LONG TERM...PA
AVIATION...KL/BJH
FIRE WEATHER...PA
MARINE...KL/BJH
Area Forecast Discussion
National Weather Service North Platte NE
815 PM CDT Mon May 18 2020
.UPDATE...
Issued at 815 PM CDT Mon May 18 2020
Sky cover was increased tonight after midnight especially across
central and eastern areas. The latest RAP and NAM models are
forecasting stratus to develop later tonight and last until mid
morning Tuesday. The remainder of the forecast remains unchanged.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 255 PM CDT Mon May 18 2020
Ridging and mid-level height rises continue to dominate the weather
pattern across central and western Nebraska as quiet weather
continues towards mid-week. Morning stratus across much of central
Nebraska is starting to dissipate as low-level winds veer and warm-
air advection increases across the area. Winds will remain generally
out of the south through the next few days, helping to advect better
moisture in the area that`ll set the stage for periodic rain and
thunderstorm chances, mainly covered in the Long Term discussion.
For the rest of Monday, dry conditions are expected as the area
falls between the troughing in the west and east. Temperatures will
generally remain at or above normal for mid-May standards with lows
falling into the 40s and 50s, or generally around 5 degrees above
climatological lows. Winds off the surface will increase tonight as
mid-level heights compress and a modest low-level jet develops.
Strongest winds will remain west of Highway 83 where occasional
gusts of up to 20 mph will be possible overnight.
Dry conditions are again expected for most if not all locations on
Tuesday as shortwave ridging peaks over the area during the daytime
hours. Mid-level moisture advection may lead to redeveloping stratus
across portions of the area, particularly the eastern half of the
CWA. This may help to limit daytime heating slightly, though
temperatures are anticipated to be warmer than what was seen Monday.
High temperatures will range from the mid 70s in the east to low 80s
in the west. Breezy south winds will be prevalent for areas west of
Highway 83, where gusts may be as high as 25 mph. With the continued
push of better moisture into the Panhandle region, dew points look
to climb into the mid to upper 50s. This combined with the warm
temperatures should lead to some modest instability developing with
MLCAPE values of 1500-2000 j/kg with 0-6km BWD values in the 25-35
knot range. Conditions will be supportive of strong to severe
thunderstorms further west from the local area, the question is how
far east does activity make it if at all. Shear vectors and corfidi
vectors while initially look to steer any high plains activity into
the local area during the afternoon, will make a sharp turn more
south to north during the evening hours and so confidence in storm
threat to the local area is low at this time. Though unlikely,
should a storm form earlier in the afternoon the threat to the
Deuel/Garden/Sheridan Counties line would increase. Since this
outcome doesn`t appear likely, have decided to remove what little
PoPs there were Tuesday evening. Another low-level jet is expected
to develop Tuesday night and is anticipated to be stronger than the
previous night`s. This in combination with better low-level moisture
and increasing temperatures at h85, should see an even warmer
morning on Wednesday with low temperatures in the 50s for all.
Occasional wind gusts overnight could once again approach 20 mph.
.LONG TERM...(Wednesday through Monday)
Issued at 255 PM CDT Mon May 18 2020
Beginning 12z Wednesday. The long awaited trough from the west will
begin its approach during the daytime Wednesday. Height falls will
begin early and persist through the daytime hours. Temperatures will
be warm again with highs generally in the upper 70s, or 5-8 degrees
above normal. Moisture advection across the western tier of counties
will reintroduce partly to mostly cloudy skies by the afternoon. A
strong vort max will pivot across the eastern periphery of what will
by then be a negative tilt trough centered over the northern
Rockies. This, working in concert with a surface cool front expected
to take shape during the day, will be the focus for scattered rain
and thunderstorms during the late afternoon and evening. Have slowed
down the arrival of precipitation slightly locally owing to a strong
capping inversion and timing of the greatest forcing for ascent. As
a result, only have Slight Chance PoPs along and west of a Lewellen
to Gordon line prior to 00z Thursday. Temperatures at h7 will be in
the low teens, which is leading to strong CIN. What storms that do
form on the High Plains will likely be moving north to north-
northeast due to the highly amplified flow with shear vectors and
corfidi vectors all oriented south to north. Believe the strong to
severe thunderstorm threat to be rather limited locally as
instability drops off significantly the further east you get with
nearly 2000 j/kg of MUCAPE along the western border or Garden County
to less than 1000 j/kg east of Highway 61. Do believe some eastward
progression of convection is expected late Wednesday into early
Thursday, however, due to the surface boundary moving east with
time but no strong to severe weather is expected overnight.
The frontal boundary will likely stall across the area on Thursday
and serve as the focus yet again for rain and thunderstorm
development during the day. A second vort max rotating around the
parent trough across the northern Rockies will be the source for
forcing as divergence aloft increases during the day. How far east
this frontal boundary makes it will play a large role in where the
greatest PoPs will be and thus the greatest QPF falls. For now, have
Likely PoPs along and east of a North Platte to Ainsworth line but
adjustments in the coming days will be likely. High temperatures
Thursday are medium confidence at best with general highs in the 70s
expected. The extended forecast remains active as troughing
continues in the west with additional disturbances moving through
the area and an unimpeded flow from the Gulf of Mexico. Temperatures
heading into the weekend look to be above normal with 70s and 80s
expected Friday and Saturday but falling to the 60s and 70s for
Sunday and Memorial Day. Right now, the holiday weekend appears to
be fairly active across the region but long, appreciable breaks are
likely locally with the best rain/thunderstorm chances on Saturday.
High pressure works in the start the following week with an
anomalous disturbance churning over Texas but cutting off local
moisture sources and keeping forcing for ascent out of the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 634 PM CDT Mon May 18 2020
Main aviation concern will be the development of IFR ceilings late
tonight. IFR ceilings are forecast to develop in central Nebraska
including KBBW and expand westward to include a BKN004 ceiling at the
KLBF terminal by 11Z and lasting until at least 13Z. Latest
mesoscale models indicate stratus development, with the westward
extend still in question. IFR ceilings may also include KVTN, and
have included a SCT004 12Z-15Z. Further refinement is likely with
the next scheduled TAF issuance at 06Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Roberg
SHORT TERM...Jurgensen
LONG TERM...Jurgensen
AVIATION...Roberg
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
924 PM EDT Mon May 18 2020
.DISCUSSION...
Currently-Overnight...Showers and a few storms ascd with diurnal
heating and large scale instability across the region will move
offshore the Treasure Coast over the next couple of hours. The
recently updated forecast keeps isold/sct chcs possible during the
overnight, mainly due to shortwave axis which will move across the
state overnight. stronger jet level winds combined with suitable
moisture and UL temp profile may lead to onset of some additional
convection overnight, esp across the south, where HRRR guid suggests
some re-development overnight.
Tuesday...As the UL wave shifts east of the area by Tuesday morning,
models have drier air moving in, which will gradually end rain
chances across north central Florida. However, sufficient moisture
and instability to the south, ahead of a weak surface trough may
lead to additional scattered showers and storms into the late
morning and afternoon, especially across Okeechobee County and the
Treasure Coast. A few stronger storms may still be possible with
this activity, before it shifts offshore by the evening, with rain
chances then ending across the area.
&&
.AVIATION...
Will keep a low shower chance overnight most of area, with mention
of showers across southern sites primarily VRB-FPR-SUA. A dry slot
in the mid levels will work in north of a KISM-KTIX line on Tuesday
substantially lowering rain chances with mainly VFR conds. Expect
SCT SHRA/TSRA in the KVRB-KSUA corridor Tue afternoon.
&&
.MARINE...
Tonight...Main boating concern will be with a few stronger storms
that may still push offshore through midnight, south of Sebastian
Inlet. Otherwise winds will be out of the S/SW around 10-15 knots
with seas 2-4 feet.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
JP/JC