Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/04/21
Area Forecast Discussion
National Weather Service Bismarck ND
922 PM CST Wed Mar 3 2021
Issued at 918 PM CST Wed Mar 3 2021
Minor adjustments were made to low temperatures tonight and high
temperatures tomorrow. Some parts of southwest North Dakota have
already seen temperatures fall near the inherited forecast
minimum. Lows were decreased by a few degrees mainly along a line
from Glen Ullin to Hettinger, and also near Beach. High
temperatures tomorrow were lowered by a few degrees at most
locations. The reasoning for this is that weak easterly flow is
not as conducive to strong diurnal mixing, and the current
forecast was already approaching the NBM 90th percentile. But
forecast highs were kept at least as warm as the NBM 75th
percentile. Most bias-corrected guidance is actually much colder
east of Highway 83, but we think non-RAP/HRRR models are
over-simulating low-level moisture.
The mention of patchy fog was brought a little farther west based
on latest mesoscale guidance trends, which now brings it to most
areas along and east of Highway 83.
UPDATE Issued at 544 PM CST Wed Mar 3 2021
No major changes are needed for this update. The most notable
adjustment was to the coverage of patchy fog tonight through
tomorrow morning, which generally extends from north central North
Dakota into the James River Valley. A model blended approach of
visibility output was used to define the areas of patchy fog,
excluding the RAP as it is currently a far western outlier.
.SHORT TERM...(This evening through Thursday)
Issued at 215 PM CST Wed Mar 3 2021
Overall dry and warm conditions will persist through the short
term period, possibly elevating the fire weather danger threat.
Other than a few passing high clouds the rest of tonight looks to
be mainly clear and dry with mild temperatures. Light winds and
high RH values could provide for some patchy fog, especially in
local river valleys. Much of the same is expected for Thursday as
a ridge of high pressure remains overhead and a weak surface low
form in MT. The result will be high temperatures again in the 75
to 90th percentile resulting in widespread 50s and 60s. Low may
develop a light breeze out of the east tomorrow afternoon. The
result could be some elevate fire danger, especially in the
southwest. Winds may not quite be high enough for critical fire
danger, however, local burn bans should be observed.
.LONG TERM...(Thursday night through Wednesday)
Issued at 215 PM CST Wed Mar 3 2021
The long term sees a warm start followed by potentially active
weather. Thursday night through the weekend sees the ridge
overhead further amplify across the region. The result will be
temperatures warming into the 75th to 90th percentile, which
results in widespread 50s, 60s, and perhaps some low 70s. Elevated
fire danger will be found each of these days. Saturday as the
ridge progresses eastward and returns dry southerly flow, look to
see the warmest temperatures across the region with perhaps some
70s. This might also be one of the breezier days further elevating
the fire weather threat to perhaps near critical. A weak and dry
cold front then looks to move through Sunday into Monday. This
will cool temperatures somewhat, yet still see them remain above
normal. Breezy winds may also be found at times.
A potential low pressure system could still bring impacts to the
area on Tuesday and Wednesday. Ensembles and plume data still
showing a wide range of possible solutions. To start there are
still plenty of timing and amplitude differences to work out,
however, most guidance indicates an early to mid week event. Much
of the differences deal with the possibility of a split flow
regime, which has been common occurrence this winter sending
storms to our south. However, there are enough indications a
northern track or a larger wave is possible. QPF wise as expected
has a wide range, although most ensembles indicate 50-60 percent
chance of 0.1 inches of QPF and perhaps 10 to 30 percent chance of
at least a half inch across the area. Combine that with the fact
there could be ample warm weather followed by a cold front, the
worst case scenario of this system brings widespread rain and
snow. Overall there remains much uncertainty with this system, and
if the high impact solution comes a reality widespread impacting
snow and much needed rain is possible across the area. Current
forecast keeps in the NBM blend and will have to continue to
monitor the setup of this system.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 544 PM CST Wed Mar 3 2021
Fog or very low stratus clouds may develop at KMOT and KJMS
overnight. Confidence is high enough to introduce a TEMPO group
for IFR visibility and LIFR ceilings with this issuance.
Otherwise, VFR conditions are expected with light winds. Surface
flow will become easterly on Thursday.
Area Forecast Discussion
National Weather Service Lake Charles LA
925 PM CST Wed Mar 3 2021
Clear skies and light to calm winds will prevail through the night
with high pressure nearly overhead. The ideal radiational cooling
environment is showing off the urban heat island effect on the
latest observations this evening with Alexandria, Lafayette, Lake
Charles, Orange and Beaumont all showing temperatures several
degrees (11 in the case of Alexandria) higher than the surrounding
Only change to the forecast this evening was to add patchy fog
wording across the area through the early morning as the HRRR and
NAM are both hinting at radiation fog. The clear skies should
allow any fog that develops to clear by 14Z.
.PREV DISCUSSION... /issued 540 PM CST Wed Mar 3 2021/
For the 03/04/21 0000 UTC TAF package.
VFR is expected to continue to prevail the rest of the evening and
into the overnight amid SFC high pressure and a generally dry
atmosphere, with light winds and a clear sky yielding some
possible radiation fog toward early THU morning. Inserted a TEMPO
each site for this potential, with VFR expected to prevail once
any fog erodes by mid morning.
PREV DISCUSSION... /issued 345 PM CST Wed Mar 3 2021/
Mid-afternoon sfc analysis shows high pressure centered over the
ArkLaTex controlling our area weather at the moment, with a light
nerly low-level flow holding dewpoints generally in the 30s. Water
vapor imagery shows a general zonal flow aloft while our next
weather maker begins to get cranked up along the West Coast. Sfc
obs/satellite imagery show clear skies continuing across the
region with temps nearing seasonal high values. Regional 88Ds are
Another night of clear cool conditions looks on tap for tonight as
the sfc high sits nearly overhead. Some of the fog guidance is
pushing for some development late tonight primarily over the nern
zones...however despite good radiative conditions, have elected to
hold out of the forecast for now with the uncertainty of true
boundary layer saturation at this time. Mostly sunny conditions
are forecast for Thursday along with some warming as a low-level
return flow sets up during the afternoon and forecast soundings
indicate temps aloft beginning to warm.
The storm system crossing SoCal this afternoon is progged to
proceed swiftly ewd over the next 48 hours, moving into wrn TX by
Friday and helping induce sfc low pressure development over the Red
River Valley at that time. With a deepening onshore flow
developing prior to its arrival, expect scattered showers/few
storms to develop over the area by late Friday, continuing through
the evening as the system pushes esewd into the forecast area.
Precip should shut off by the early morning on Saturday as drier
nrly flow sets up through the column behind the system. Expect
clearing skies by late in the day and slightly below normal temps.
Fairly benign weather anticipated through the remainder of the
weekend and early next week. One quick passage of a mid/upper-
level disturbance Sunday night into Monday is expected to only
bring a quick shot of additional cloud cover as low-level
moisture return isn`t expected in time to allow additional low-
level moistening. Temps will start on the cool/seasonal side with
lows generally in the 40`s before the warming commences (highs in
the 70`s by Tuesday). Next rain chances appear to accompany the
system on Wednesday, although at this time it doesn`t appear
chances are high for a frontal passage as mid-level flow stalls
from the southwest prior to the boundary`s arrival.
No flags are anticipated on the coastal waters through this
.PRELIMINARY POINT TEMPS/POPS...
AEX 37 69 45 66 / 0 0 0 50
LCH 41 69 48 68 / 0 0 0 40
LFT 40 69 46 69 / 0 0 0 30
BPT 42 68 50 68 / 0 0 0 40
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
748 PM CST Wed Mar 3 2021
Issued at 748 PM CST Wed Mar 3 2021
An area of mid level stratus continues to shift east from central MN
into western WI. Clear skies are expected outside of this area of
stratus. Models are much too aggressive with the stratus overnight
and Thursday as there is virtually nothing off to the west. There is
a possibility of fog or low stratus to develop overnight, but you
usually see some low stratus somewhere by now if it will become
widespread during the next several hours. Trended the sky cover down
a lot tonight into Thursday.
The upper pattern doesn`t change much for the next few days.
Light/variable or light easterly winds will continue. Highs today
surpassed NBM by a whopping 10 degrees and even topped the 95th
percentile in some instances. Models are simply giving the existing
snowfield too much credit for limiting potential heating. Raised
highs through Saturday to levels slightly cooler than seen today,
but still near the 95th percentile, so wouldn`t be surprised if we
had even warmer highs. On top of that, the snow will continue melting
and will become an even smaller factor in the coming days.
.SHORT TERM...(This evening through Thursday night)
Issued at 222 PM CST Wed Mar 3 2021
Satellite imagery this afternoon shows clear to partly cloudy skies
over most of the area, with a bit more cloud cover over the northern
portion where some thicker mid clouds have been able to develop along
the eastern periphery of the upper ridge and leading edge of slightly
better mid-level moisture. RAP analysis actually show some whopping
MUCAPE values of around 10-15 J/Kg in that area at the current time.
Overall, it will remain quiet through the short term as the surface
high drifts to the east. We will see an increase in mid/high clouds
across the entire area, and some SCT-BKN lower (around 5k ft AGL)
clouds later tonight into Thursday.
.LONG TERM...(Friday through Wednesday)
Issued at 222 PM CST Wed Mar 3 2021
The warming trend looks to persist through the weekend as the upper
ridge builds east and amplifies across the central part of the
country. The warmest temperatures look to come during the Sunday-
Tuesday time period ahead of an upper trough that will eventually
work to cool things back down to near normal for the middle to end of
next week. The numerical guidance is in anything but good agreement
on forecast details beyond Sunday, but there is enough consistency in
the ensemble guidance to favor a general return toward more normal
conditions later next week. As often happens during such transitions,
a storm looks to be involved, with varying depictions of a moderate
to strong system over the central US in the Tuesday to Wednesday time
frame. For now, simply bumped up chance PoPs for Tuesday into
Wednesday in line with the NBM consensus. The preponderance of
guidance still lifts the system by to our west/northwest, keeping us
in the warm sector with rain for our area. Things are obviously a
long way off, so will certainly require some watching, but at this
point it appears we`ll see warming temperatures through Monday or
Tuesday, then a period of rain (and possibly some thunder, although
it`s too early to mention that given the uncertainty) before we
return to more typical March temperatures (at least for a little
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 549 PM CST Wed Mar 3 2021
Mid level clouds will exit to the east this evening. Will need to
watch for fog and/or stratus development overnight, but wind should
keep from decoupling in western MN. Wind has already decoupled in
eastern MN and WI, but air is drier in WI than this time yesterday,
so fog potential shouldn`t be quite as high.
/OUTLOOK FOR KMSP/
FRI-SAT...VFR. Wind ESE-SE 5 kts.
SUN...VFR. Wind S 15G30 kts.
Area Forecast Discussion
National Weather Service Reno NV
244 PM PST Wed Mar 3 2021
Mild temperatures will rise to well above average Friday. Breezy
winds Thursday afternoon will increase Friday. Except for a few
snow showers this evening in Mono County, dry conditions will
prevail through Friday evening. Cooler temperatures and chances
for mountain snow and valley rain and snow return Saturday with a
more active winter weather pattern possible for much of next week.
The main change to the short term forecast was to increase winds
Friday and Friday night.
Low pressure is moving ashore over southern California this
afternoon. It is mostly just a mid and high cloud maker for
northeast CA, the Sierra, and western NV; however, as it scoots
over southeast CA and southern NV this evening there remains a
lower-end chance for some very light snow over western Mono
County and in the White Mountains. Given the HRRR now shows
nothing east of the crest and slightly less than half of EPS
members show any snow at all in southern Mono County, chances
mostly remain at less than 50%. In any case, little impact is
expected as trans-Sierra passes are closed and Hwy 395 is unlikely
to see more than a brief snow shower here and there (and then only
south of Mono Lake).
Thursday and Friday, south flow increases over the Sierra and
western NV in between a ridge axis over the eastern Great Basin
and a trough approaching the West Coast. These increased winds
and less overall cloud cover will improve mixing and push
temperatures up into the upper 50s to upper 60s across most lower
elevations with 50s for Sierra valleys. Friday looks to be the
warmer and windier day. Wind speeds don`t look overly strong
into Friday evening with gusts mainly 25-35 mph with Sierra ridge
gusts 60-80 mph. However, a burst of winds could accompany the
trough passage later Friday night.
As for precipitation, the system for late Friday night and
Saturday remains a fast-mover. Thus, snowfall amounts in the
Sierra and parts of northeast CA look to be limited; however,
snowfall rates could briefly ramp up near the trough passage
Saturday morning for some travel concerns. More on that below.
.LONG TERM...Saturday into next week...
*Main Message: Colder and wetter pattern change likely beginning
this weekend and extending into next week.
Changes made this forecast cycle:
*Increased POPs for Friday night-Saturday system as well as
throughout next week mainly for northeast California, the Sierra,
and extreme portions of western Nevada.
*Decreased high temperatures for next week.
Confidence continues to increase in a colder and wetter pattern
change across much of the western United States through much of next
week, starting out with an appetizer system for Friday night into
Saturday. Following the gusty winds on Friday, moisture moves into
the region for Friday night. The overall progression of this storm
remains quick according to the recent model guidance with peak
precipitation intensity from midnight Saturday through Saturday
While most of the precipitation will likely fall as snow during this
time in the Sierra, elevations around and below 5000 ft in Lassen
and Plumas counties could see a rain to rain-snow mix first before
snow levels drop to all valley floors by Saturday morning as the
shortwave trough`s front sweeps through. Even though the ensembles
as well as the deterministic GFS and ECMWF show the system pushing
through the region rather quickly, the trough looks to be dynamic
becoming more negatively-titled as it treks over the Sierra and
western Nevada. If the strength of the shortwave does indeed
materialize, then this would provide sufficient forcing enough to
see some intense snowfall rates for a short period of time in the
Sierra. This would include the Tahoe Basin and the Sierra passes.
Because of the more southerly flow, most of western Nevada is
expected to be shadowed out for the majority of this storm. As of
now, best chances for some light rain-snow mix to snow showers
for these locations would be Saturday morning, coinciding with the
trough`s frontal passage.
Here are the current NBM snow probabilities across the region:
Susanville: 10% chance for >1"
Truckee: 15% chance for >3", 45% chance for >2"
South Lake Tahoe: 25% chance for >3", 50% chance for >2"
Sierra Foothills: 25% chance for >1"
Reno-Carson City: 40% chance for a coating
Mammoth Lakes: 15% chance for >2"
The areas most likely to be impacted will be the Sierra passes where
3-6 inches of snow is possible. Expect hazardous travel during this
After a brief break on Sunday, most, if not all forecast guidance
points to a general trough setting up over the West for most of next
week. At this time, no significant atmospheric river type systems are
expected; however, the pattern overall looks to favor a 3-4 day
period of waves containing modest moisture with the potential for
a few inches of liquid equivalent moisture across the Sierra during
this period. The GEFS, EPS, and the Day 3-7 WPC Clusters all show
this potential outcome which has increased our confidence in not
only precipitation chances but also colder temperatures across the
region. Winds do not look too impressive at this time due to the
core of the upper-level jet remaining towards the south of the
forecast area for next week. To sum up, anticipate high and low
temperatures 4-8 degrees below average, periods of precipitation,
breezy to gusty southwest winds, and Sierra travel impacts from
Monday through next Thursday. -LaGuardia
VFR conditions will prevail through Friday. The only possible
exception is in Mono County west of Highway 395 into this evening
where terrain obscuration with isolated to scattered -SHSN are
possible. For KMMH, it is likely to remain VFR although brief
-SHSN are possible.
South winds will begin to increase in higher elevations Thursday
and Friday, with some of these winds mixing to the terminals.
The main effect would mainly be increased turbulence, although
the potential for LLWS may increase Friday night/early Saturday
with a fast moving trough passage. -Snyder/MJD
For more information from the National Weather Service visit...