Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/03/21
Area Forecast Discussion
National Weather Service Bismarck ND
859 PM CDT Fri Apr 2 2021
.UPDATE...
Issued at 859 PM CDT Fri Apr 2 2021
The Red Flag Warning was allowed to expire on time. For this
update, we decided to issue a Fire Weather Watch for south central
North Dakota and the James River Valley Saturday afternoon and
early evening. There is high confidence in relative humidity
falling into the 10 to 15 percent range across nearly all of
western and central North Dakota. The watch was limited to areas
where there is higher confidence of sustained winds reaching 20
mph. This area also contains a wind direction shift from southerly
early in the afternoon to westerly by late afternoon.
UPDATE Issued at 536 PM CDT Fri Apr 2 2021
Critical fire weather conditions continue across much of the area
late this afternoon, with a wide swath of northwest winds around
20 mph overlaying relative humidity under 20 percent across
central North Dakota, and closer to 10 percent in south central
North Dakota. Parts of LaMoure and Dickey Counties may see an hour
or two of critical fire weather conditions before sunset, but
this duration does not warrant them being added to the ongoing
Red Flag Warning.
We are now evaluating the potential for another round of critical
fire weather conditions tomorrow. All of western and central North
Dakota is expected to see minimum relative humidity drop into the
10 to 15 percent range. The strongest winds of around 20 to 25
mph out of the south are expected from the Missouri and James
River Valleys up to the Devils Lake Basin. We will continue to
evaluate the most recent guidance and make any adjustments to the
forecast as needed.
&&
.SHORT TERM...(This afternoon through Saturday night)
Issued at 245 PM CDT Fri Apr 2 2021
Fire weather concerns continue to be the main weather story for
the short term forecast period.
The general story remains the same for this afternoon through
Saturday, just with slightly different details. Relative humidity
values across almost all of western and central North Dakota
continue to dive. Hettinger airport is currently observing the
lowest humidity value of 9 percent but others will likely follow,
dipping below 10 percent. Much of the area is currently sitting
below 20 percent. Winds also continue to increase with more
afternoon mixing. Behind a surface pressure trough (currently
approaching the southern James River valley), winds will be out of
the northwest sustained around 20 mph. Gusts up to 30 mph will be
possible. Thus, the Red Flag Warning looks to be in good shape.
Thus far abundant high clouds haven`t really impacted temperatures
or mixing and clearing has already started across the northwest.
Tonight, winds will relax, humidity will come up, and fire
weather conditions will improve. Expect lows in the 30s. As we
turn the page to Saturday, fire weather concerns present
themselves to be a challenge once again. Near critical fire
weather conditions will be possible across pretty much all of
western and central North Dakota, but another Red Flag Warning
will likely be needed somewhere across the area. At this time, the
most likely area will be generally across the far south central
and east of the Missouri River. Here, afternoon humidity values
will range from 10 to 20 percent, overlapping sustained northwest
winds up to 25 mph and gusts to 35 mph. Elsewhere the very dry air
will be in place, but winds will be lower. That being said, there
is still some uncertainty about how widespread the sustained
winds of 20 mph or greater will setup. Because of this uncertainty
and the fact that we already have a Red Flag Warning out for
today, we will not be issuing headlines for tomorrow yet as to
avoid any confusion.
For today`s dewpoints, stuck with the latest time lagged HRRR as
it typically does very well in these setups. And for tonight and
tomorrow, generally went with the latest time lagged RAP.
Regarding high temperatures for Saturday, stuck with the trend of
using the NBM 75th percentile which brings widespread 70s to the
area with a few lower 80s across the far southwest. Broad ridging
starts to nudge in Saturday night and we will see lows mainly in
the 30s with a few lower 40s across the south.
.LONG TERM...(Sunday through Friday)
Issued at 245 PM CDT Fri Apr 2 2021
Another very warm day will be in place on Sunday. There continues
to be quite a bit of spread in the NBM for highs. Guidance
suggests that widespread cloud cover will be in place for much of
the day so it may be hard to reach into the upper percentiles of
the guidance. Thus, we decided to stick with the 50th percentile
for highs on Sunday which still bumped the values up a bit from
raw NBM output. Near critical fire weather conditions will once
again be possible on Sunday, but winds will be lighter.
A shortwave riding across the broad ridge (north of the
International Border) will flatten the flow on Monday,
transitioning us into a zonal pattern at least briefly. This will
lead to cooler temperatures and we also went with the NBM 50th
percentiles for Monday`s highs, nudging them up slightly from the
raw NBM output.
A more appreciable pattern change looks to start on Tuesday as a
west coast trough digs and approaches. Still quite a bit
uncertainty. At first glance, the deterministic global models look
to be in better agreement bringing a closed upper low from Wyoming
into the central or northern Plains Tuesday into Wednesday.
However, looking at the latest WPC cluster analysis and various
ensemble members, it is apparent that a very wide envelope of
solutions are still on the table, so caution is advised in trusting
any deterministic solutions at the moment. Still, it appears that
there is at least some possibility of widespread precipitation
somewhere across the central or northern Plains in the Tuesday
through Thursday time frame. For now we will keep mention of
slight chance to chance PoPs in the forecast Tuesday through
Thursday morning with the best chances on Wednesday across the
south.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 647 PM CDT Fri Apr 2 2021
VFR conditions are expected through the forecast period. Northwest
winds will diminish this evening. Wind direction will then make a
complete clockwise turn, coming back to the northwest late
Saturday morning through the early evening. Sustained winds will
reach around 15-20 kts Saturday afternoon, strongest at KXWA and
between KBIS and KJMS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for NDZ022-023-025-034>037-042-045>048-050-051.
&&
$$
UPDATE...Hollan
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...Hollan
Area Forecast Discussion
National Weather Service Dodge City KS
657 PM CDT Fri Apr 2 2021
...Updated Aviation Section...
.SHORT TERM...(This evening through Saturday)
Issued at 300 PM CDT Fri Apr 2 2021
Very strong south to southwest winds across southwest Kansas today
underneath a 40-50 knot low level jet at 850 mb. A few gusts to around
or over 50 mph were noted just before midday. This mornings RAP model
guidance has been showing the low level jet weakening somewhat and
propagating to the east. Latest surface winds/gusts at 2 pm are showing
a decreasing trend and this will continue to be the case through
the rest of today.
Upper air analysis showed strong westerly flow aloft over the northern
Rockies and adjacent Plains States. Weaker flow was noted farther
south with a closed upper low over Arizona moving east. A weak
disturbance moving out over the northern Plains will push a weak
cold front into central and southwest Kansas late tonight which
will stall out on Saturday. The decreasing winds overnight along
with lower dewpoints will allow temperatures to fall into the mid
30s to lower 40s. Winds on Saturday will be fairly light compared
to today with variable winds at 5 to 10 mph expected. With high
temperatures in the upper 70s to lower 80s, Saturday is shaping up
to be be a fine Spring day.
.LONG TERM...(Saturday night through Friday)
Issued at 300 PM CDT Fri Apr 2 2021
The extended period will see a continuation of the upper level
westerly flow pattern. This will be conducive to redevelopment of
a low pressure trough in the lee of the Rockies with a strengthening
pressure gradient and return to gusty south winds across western
Kansas on Sunday. Some of the models are breaking out isolated to widely
scattered thunderstorms near the surface trough over far western
Kansas on Sunday afternoon into early Sunday evening. CAPE and
shear values are not overly strong. Inverted V sounding profiles
would suggest high based showers and thunderstorms with virga
along with downburst wind potential.
Another upper low is forecast to drop into the Pacific Northwest
on Monday and then move east across the northern Plains through
mid week. Gulf moisture will get pulled northward into the central
Plains as broad scale southerly flow develops ahead of this system.
Surface dewpoints could increase into the 50s across central and
eastern Kansas. While details are vague at this time, there could
be potential for dryline thunderstorms somewhere across central
and adjacent portions of southwest Kansas Tuesday afternoon. A
cold front will also push through the region by Tuesday evening as
the upper system moves east.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 653 PM CDT Fri Apr 2 2021
Strong south winds at the onset of this TAF period will decrease
in strength through the evening. The south to southwest wind will
eventually become a light and variable wind at speeds of 6 knots
or less during the day Saturday as a trough axis moves east and
stalls out across southwest and west central Kansas. Flight
category will remain VFR through this TAF period amidst a
continued dry lower atmosphere and absence of deep moisture
advection from the south/southeast.
&&
.FIRE WEATHER...
Issued at 300 PM CDT Fri Apr 2 2021
Near Red Flag conditions will continue through the rest of this
afternoon. Strong south to southwest winds will continue through
the rest of today across all but the far west central Kansas
counties. Relative humidity should bottom out in the upper teen
to lower 20 percent range with a few locations in the far southwest
falling to around 15 percent for a few hours.
Conditions will be much improved on Saturday with much lighter winds
but elevated to near critical conditions could redevelop late in
the weekend and early next week as southerly winds increase.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 43 80 49 83 / 0 0 0 0
GCK 39 80 47 83 / 0 0 0 10
EHA 40 81 47 83 / 0 0 0 20
LBL 40 82 46 83 / 0 0 0 0
HYS 41 80 48 84 / 0 0 0 10
P28 43 77 48 81 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM CDT this evening for KSZ031-046-065-
066-079>081-089-090.
&&
$$
SHORT TERM...Gerard
LONG TERM...Gerard
AVIATION...Umscheid
FIRE WEATHER...Gerard
Area Forecast Discussion
National Weather Service Marquette MI
812 PM EDT Fri Apr 2 2021
.SHORT TERM...(This evening through Saturday)
Issued at 339 PM EDT FRI APR 2 2021
Water vapor imagery and RAP analysis show mid-level ridge extending
from the Plains into the Upper Great Lakes and Hudson Bay. At the
sfc, a tightening pres gradient between high pressure se into the
Ohio Valley and a trough approaching from the Northern Plains has
resulted in somewhat gusty south winds of 20-25 knots this
afternoon. These gusty winds mixing through a very dry attendant air
mass has also led to RH values in the 15-25 pct range and elevated
wildfire concerns. A SPS will remain in effect through 00Z this
evening for gusty winds and low RHs for Alger and Delta counties
westward. Weak shortwave and an associated sfc trough/frontal
boundary approaching from southern Saskatchewan/eastern Dakotas will
reach Upper MI by 12z Sat. Models indicate any waa/isentropic ascent
pcpn from system will stay north of Upper Mi tonight into Sat. Gusty
winds of today will continue into at least the evening hrs across
the n, in particular the downslope areas of n central Upper MI
(Marquette County eastward), as 40-45kt low-level jet translates
across the area. Continues to incorporate guidance from the HRRR to
raise winds and gusts as it performs well with such events. Expect
gusts up to around 35mph. The combination of gusty winds and
continue dry dew points will lead to relatively poor RH recovery
(not much better than 60%) for downsloping areas along Lake
Superior. Look for min temps mostly in the 30s, except for a few
upper 20s readings over the interior.
As the weak shortwave and associated sfc trough push into the area
on Saturday, expect continued mostly sunny, dry and even warmer
conditions. Look for highs in the 50s most areas with even lower 60s
possible over the interior west near the WI border. Closer to the
shorelines east of Marquette on Lake Superior and along Lake Mi
readings may stay in the 40s with enhanced lake breezes developing.
Did again side at or below the lower end of guidance for dew points
on Saturday given the dry air mass still in place and decent mixing
fcst. Using the mixed dew point tool and blending with bias-
corrected MET guidance yielded dew points in the 20s across much of
the area which drops min RHs into the 25 to 30 pct range over
portions of the interior west. Fortunately, lighter winds with gusts
more in the 10-15 mph range should help limit elevated wildfire
concerns.
.LONG TERM...(Saturday night through Friday)
Issued at 423 PM EDT FRI APR 2 2021
A highly anomalous blocking ridge across the North Atlantic Ocean
will be the stalwart of the long-term pattern. The general consensus
among ensemble guidance is for the blocking ridge to retrograde
toward the Hudson Bay late next week resulting in increasingly split
flow aloft. A series of undercutting troughs and potential for interactions
among those troughs will be the primary weather makers throughout
the long range. In general, above normal temperatures prevail with
precipitation chances increasing Sunday night into Monday night
then falling somewhat Tuesday through the end of the week.
However, forecast confidence decreases quickly on Tuesday as a
substantial trough enters the Plains and tracks east through the
end of the week.
The long-term period begins with a broad ridge over the Central
Plains. NAEFS analysis indicates 500 mb heights associated with
this ridge exceed the 99.5th percentile across large portions of
CO, WY, NE, and KS. Upper Michigan will initially be within a
northwest flow regime on the northeast side of this ridge. The
ridge axis shifts east into our CWA on Monday as a sharp shortwave
trough moves across the Canadian Prairies. This shortwave advects
a plume of rich moisture (NAEFS Pwat > 90th percentile) beneath
and EML with 850 mb temperatures >5C. The combination of
relatively rich moisture and steepening mid-level lapse rates
(>7C/km) should result in up to 1000 J/kg of MUCAPE. Thus, there`s
potential for a few rumbles of thunder with passing showers
primarily on Monday night as a cold front moves across the area. I
removed thunder from the grids for Monday evening/overnight since
confidence is low (~15%) in thunderstorms actually materializing.
The general consensus is for the frontal boundary to stall to our
south on Tuesday with northerly flow resulting in cooler
temperatures and extensive cloud cover. However, substantial
differences in the track of the Canadian Prairies shortwave amplify
by Tuesday as the next trough/closed low results in cyclogenesis on
the Central Plains. Where the cyclone tracks next and how it
interacts with lingering shortwave energy is difficult to know at
this time. Ensemble clustering analyses for Wednesday evening
indicates three solution clusters to choose from. Roughly 60% of
ensemble members support a southeast trajectory from the Northern
Plains into the Ohio Valley that leaves Upper Michigan in relatively
dry northwest flow aloft. The remaining 40% of guidance is almost
evenly split between easterly and northeasterly trajectories. An
easterly trajectory implies a surface low tracking just to our south
with widespread stratiform precipitation across Upper Michigan. A
northeasterly trajectory implies a negative tilt trough with
potentially heavier precipitation, but the blocking ridge to our
northeast suggests this outcome is unlikely. The observed reality of
local weather over the past 5 months favors drier solutions until a
more coherent signal for wet weather emerges.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 812 PM EDT FRI APR 2 2021
Under a dry air mass, VFR conditions will prevail at KIWD/KCMX/KSAW
through the forecast period. A low level jet over the area this
evening will result in gusty south winds at times as well as LLWS.
Winds will diminish late tonight and Saturday.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 339 PM EDT FRI APR 2 2021
Tight gradient ahead of incoming trough over the northern Plains
will sustain fairly strong s-se winds of 20-30 kt into tonight,
especially over the east half of the lake. Not out of the question
that some high obs platforms could see a few gale force gusts this
evening, including into the nearshore waters e of Marquette.
Weakening sfc trough will cross Lake Superior Sat. With the relaxing
pres gradient, expect winds blo 20kt across the lake. These lighter
winds will continue into Sun. Building high pres to the ne and a low
pres trof moving out across the Plains will then lead to increasing
se-e on Mon. Wind gusts may increase back to the 20-30kt over
eastern and north central portions of Lake Superior. The approaching
trof will weaken as it crosses the lake late Mon night/Tue morning.
As a result, winds should relax a bit for Tue. The approach of
another low pressure system from the Central Plains will lead to
increasing ne winds on Wed, especially over the west half where
gusts could reach 25-30 knots over the western third.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...EK
AVIATION...JLB
MARINE...Voss