Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/07/21
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
956 PM CDT Wed Oct 6 2021
...Short Term Update...
Issued at 954 PM CDT Wed Oct 6 2021
THE BASICS: Regarding "beefing up" of fog potential for Thurs AM
(especially in our eastern zones):
Well, another night and another round of late night/early morning
fog potential it appears. To be very honest, fog potential for
tonight has ramped up a bit in various model visibility progs
(particularly HRRR/RAP13) since the original afternoon discussion
came out hours ago. As a result, have added generic "patchy fog"
potential to the ENTIRE coverage area (CWA) from at least 5-9 AM,
and have introduced "areas of fog/visibility less than 1 mile" to
mainly Nebraska counties east of Hwy 281. These eastern areas
actually stand a chance for at least patchy dense fog (visibility
1/4 mile or less), and although do not currently have enough
confidence in the ultimate coverage of potentially-dense fog to
issue a formal Dense Fog Advisory, have at least introduced the
possibility to the Hazardous Weather Outlook (HWOGID), and will
defer to overnight and possibly day shifts to address the possible
need for an Advisory.
The overall synoptic setup for early AM fog development appears
relatively similar to last night/early Wed AM (when at least
patchy dense DID in fact develop especially some central/eastern
counties). And if anything, the last several hourly runs of the
HRRR/RAP are hitting potentially dense fog potential a bit harder
than last night (especially for far eastern counties along/near
Hwy 81). Like last night, we will have at least mostly clear skies
and fairly light southeasterly breezes (especially eastern half),
along with high boundary layer relative humidity (RH), which if
anything may be a bit higher than last night given dewpoints
currently running low-mid 50s. As a result, there is increasing
confidence in at least "some" fog development mainly after 5 AM,
some of which could be impactful to the morning commute,
especially eastern zones. While the highest concerns (and greatest
potential for a possible eventual Advisory...NOT a sure thing of
course) resides within eastern counties, felt it would be prudent
to blanket the ENTIRE CWA with a generic "patchy fog" mention,
although SREF visibility probs suggest our far southwestern
counties would be most favored to remain largely fog-free.
QUICK NOTE ABOUT LOW TEMPS BEING LOWERED:
Last night, we saw low temps drop generally 2-4 degrees degrees
below our official forecast in many areas, and although the
slightly higher dewpoints tonight should keep things a few degrees
"warmer" than last night overall, still opted to drop lows a good
1-3 degrees from the initial afternoon forecast issuance. The
result is more of the CWA now aimed into the low 50s (versus mid
50s), and even have some upper 40s far north (Ord area).
.DISCUSSION...(This evening through Wednesday)
Issued at 243 PM CDT Wed Oct 6 2021
Main issues to consider for this forecast will be extent of
cloudiness today into tomorrow, a cold front passage Saturday
evening, and precip chance uncertainty for Sunday night into Monday.
The closed upper low meandering from Arkansas into Missouri will
continue to play havoc on our sky cover forecast for the rest of the
day into tonight as it wobbles its influence with increased sky
cover from the east, especially our eastern CWA. As for fog chances,
I really think we will have less of a chance as low-level moisture
profile looks even more shallow, the surface ridge will not be
directly overhead, and the HRRR is backing off of fog chances
compared to what was advertised this morning.
This low will finally get caught in flow that will take it farther
east by tomorrow, although we will have some clouds around, should
not see as much as today, especially in our east.
Dry period until the next wave gets closer and cold front approaches
toward Saturday night. High temperatures will trend warmer until
then. Ensembles are generally trending toward strengthening of the
shortwave trough moving through from the southwest Sunday night into
Monday. ECMWF is significantly stronger than the GFS is advertising
and thus producing well over an inch of rain for most of the CWA
with this system, while the GFS gives very little. With given
trends, I would not be surprised to see an increase in POPs for
Sunday night into Monday with future forecasts. With the potential
of a stronger wave, I stuck in thunder for Sunday night into Monday.
Kept thunder for parts of the CWA in for Tuesday.
Cooler temps are still expected behind the cold front Saturday
evening, with highs Sunday and beyond in the 60s to mid 70s.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 716 PM CDT Wed Oct 6 2021
The period is almost guaranteed rain-free, and confidence is high
that at least the vast majority of the time will feature VFR
ceiling/visibility. In fact, the TAFs officially reflect VFR
throughout, although there are admittedly some question marks
especially between 10-15Z as there is a non-zero chance for at
least brief fog and/or low ceilings.
High confidence that the vast majority of the period is VFR,
featuring no more than very limited clouds (both low and high
level possible)...and actually prevailing mostly clear most of the
time. However, after seeing a round of "sneaky" fog briefly become
an issue Wednesday AM, am a bit concerned that a "repeat
performance" could try to occur Thursday AM as well given fairly
similar conditions. Most models/guidance focus any
widespread/potentially dense fog issues at least 25-50 miles east
and/or north of KGRI/KEAR, but at least light MVFR fog (and
perhaps a brief MVFR/IFR ceiling) would not be a big surprise. For
now, have only opted to "hint" at possible reduced visbility with
a low-end VFR "6SM BR" group focused 10-15Z, and will defer to
later issuances to keep a close eye on visibility/ceiling trends.
Things are more straightforward here. Direction will remain fairly
consistent from southeasterly to south-southeasterly. Speeds
overnight will average under 10KT, but by late morning-early
afternoon Thursday a touch of breeziness will kick in with
sustained speeds averaging around 12-13KT/gusts 15-20KT.
Area Forecast Discussion
National Weather Service Goodland KS
950 PM MDT Wed Oct 6 2021
.SHORT TERM...(This evening through Thursday)
Issued at 241 PM MDT Wed Oct 6 2021
RAP analysis and water vapor imagery shows a large low pressure
system over the Missouri Valley region and a trough located over the
Rockies. The start of the afternoon has the forecast on track as
these two synoptic features begin to collide with one another which
is resulting in tightening of pressure gradients over the Tri-
State area. Winds have gusted slightly higher than expected at
KGLD with 33 mph the strongest observed thus far. The remainder of
the afternoon is expected to remain dry as the Tri-State area
remains in between the two systems, showers develop along the
Front Range and move east late this afternoon and into the
evening, but confidence is currently low if they will be able to
sustain themselves into the eastern Colorado counties. Tonight,
clouds move in west to east as the trough moves by just to the
west of the CWA. Guidance has been indicating that a piece of
energy breaks off from the trough and moves through Yuma and Dundy
counties. This along with forecast soundings showing moistening
mid levels through the night which will create the chance for
sprinkles and perhaps and an isolated light rain shower through
sunrise. Overnight lows are forecasted to be in the mid 40s to
Thursday, elevated fire weather concerns continue for eastern
Colorado, albeit slightly tempered from previous days as RH values
fall into the low to mid 20s. Breezy winds in the morning due to a
surface low over SW Kansas will gradually decrease through the day
with afternoon highs mainly in the low 80s; morning wind gusts of 20-
25 miles per hour are possible along and south of Interstate 70.
Thursday night clouds again increase from the west as overnight lows
fall into the mid 40s to lower 50s across the area.
.LONG TERM...(Friday through Wednesday)
Issued at 250 PM MDT Wed Oct 6 2021
Friday...the upper level pattern features the forecast area under a
fast southwest flow aloft, in between an upper level trough along
the west coast of the country and an upper level ridge from Texas
northeast into the northern plains. High clouds are expected to move
across the area from southwest to northeast with no precipitation
expected. High temperatures are forecast to reach into the low
to mid 80s. Overnight low temperatures are expected to be
in the low to mid 50s.
Saturday...Fridays west coast trough shifts east into the northern
plains southwest into New Mexico as a larger upper level trough
approaches the Pacific Northwest. High clouds will continue to
periodically streak across the area from southwest to northeast.
There is a bit of moisture in the 700-500mb layer that move into the
northern portion of the area during the late afternoon and evening
hours sliding east and south after midnight supporting a slight
chance for some rain showers. Southwest winds pick up a bit across
far eastern Colorado in the afternoon ahead of a cold front that
moves through the area during the night. High temperatures reach
into the mid 70s to low 80s in far eastern Colorado, low 80s to
around 90 elsewhere, hottest in the Hill City area. In fact, the
forecast high of 90 degrees in Hill City would tie the record high
for the date set back in 1965. Low temperatures drop into the low
40s to low 50s.
Sunday...a closed upper level low associated with the trough
mentioned above approaches the Texas panhandle in the afternoon then
toward eastern Kansas overnight. There are some timing differences
between the GFS and ECMWF regarding the speed of movement with the
GFS faster. The current forecast follows the slower ECMWF and
supports rain showers/possibly a thunderstorm. High temperatures
cool down into the mid 60s to mid 70s with low temperatures in the
upper 30s to upper 40s.
Monday...a significant change in the weather patter begins with the
GFS/ECMWF/Canadian and GEFS models in good agreement carving out a
strong/deep upper level low pressure area over Nevada and Utah by
sunrise Tuesday morning. Rain chances decrease from west to east
during the day with sunshine returning to much of the area. Dry
conditions are currently expected during the night. The ECMWF is a
little faster bringing some moisture in the 850-500mb layer and
perhaps a rain shower into parts of far eastern Colorado. High
temperatures remain in the mid 60s to mid 70s. Low temperatures are
expected to be in the upper 30s to upper 40s.
Tuesday...the 12z GFS/ECMWF/Canadian and GEFS models shunt the deep
closed upper low into the four corners area during the day with a
deepening surface low somewhere across eastern Colorado. The
synoptic setup is favorable for blowing dust/possible dust storm
conditions. Based on the GFS model and local ongoing research the
parameters are favorable for an organized threat of blowing dust and
unhealthy air quality to move northeast out of south central
Colorado and into our area (mainly across far eastern Colorado)
during the afternoon. The ECMWF wind profile isnt nearly as
favorable. Stay tuned as any shift in the upper level low will
shift the axis of strongest winds, either to the west of our area or
east or completely fall apart. High temperatures range from the
upper 60s to upper 70s. Surface winds will likely need to be
increased as well given the pressure gradient. A few rain showers
and thunderstorms are possible, mainly along the KS/NE border and
eastern CWA while the rest of the area is dry slotted.
For the overnight hours there is some timing differences regarding
how the upper low lifts northeast. The GFS is faster putting the
upper low into the Nebraska panhandle while the ECMWF has it near
the Palmer Divide. The Canadian model has it over south central
Colorado. The GEFS has it in between the GFS and ECMWF. The
timing of this is critical in how cold temperatures get on the
backside of the low, if at all. Currently low temperatures are
expected to range from the low to upper 30s in far eastern
Colorado to the upper 30s to near 50 east of the CO/KS border.
Despite the current forecast of slight chance and low chance pops
there is a pronounced mid level dry slot over all but the far
eastern Colorado counties which should limit qpf potential quite a
bit. But for now will keep the pop forecast going. So with that
said we`ll be watching for the possibility of some snow mixing in
with some rain around the Flagler area. Confidence is rather low
in the precipitation and temperature forecast at this time.
Wednesday...The dynamic storm system lifts northeast into the
northern plains with precipitation chances decreasing from south to
north during the day. Breezy west to northwest winds are expected.
High temperatures are expected to be in the mid 50s to low 60s in
far eastern Colorado, low 60s to around 70 elsewhere.
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 946 PM MDT Wed Oct 6 2021
At KGLD terminal, VFR conditions are expected through the TAF
period. Southeast winds are expected to gradually diminish after
midnight. There is a brief period between 07 and 09Z where some
low level wind shear may be possible. Winds turn light and
variable around sunrise, becoming northerly by mid-morning around
09kts. Winds become light and variable in the afternoon.
At KMCK, VFR conditions are expected for the forecast period.
Southeast winds persist through the overnight hours. A brief
period of low level wind shear will be possible between 08 and
11Z. Low confidence in the potential for some patchy fog to
develop around 12Z in the vicinity of the terminal. Winds through
the day will be light and variable.
Issued at 250 PM MDT Wed Oct 6 2021
A record or near record high temperature is possible at the
following location Saturday, October 9:
Hill City..........90 degrees set back in 1965
Area Forecast Discussion
National Weather Service Wilmington NC
815 PM EDT Wed Oct 6 2021
Showers and storms will gradually increase this week as tropical
moisture moves into the region. Above normal temperatures are
expected much of this week, particularly morning lows. Unsettled
weather will continue into early next week as a wave of low
pressure meanders off of the Southeast coast.
Minor adjustments to previous forecast based on current radar
trends. High res near term guidance not handling current
situation very well. HRRR having trouble with the activity near
Cape Fear, but there is an area of enhanced moisture at
850/700mb showing up in the high res guidance. This moisture
combined with some weak isentropic lift is likely the cause of
the ongoing activity. The enhanced moisture in these layers
slowly shifts west-northwest during the overnight hours and
remains in the vicinity of weak speed enhancement at 850/700mb.
Not significant enough to call it a low level jet, but it is
likely to play a role in rain/showers continuing overnight.
Temperatures well above climo with clouds and tropical moisture
.NEAR TERM /THROUGH THURSDAY NIGHT/...
Tropical moisture feed via onshore low level flow will maintain
scattered showers across NE SC through this evening. Ample cloud
cover has kept showers shallow and lightning free. A swath of
precipitable water near 2" moves up the coast tonight as a tropical
wave strengthens as it moves up the SE coast. Best chance of rain
will be near the coast from south to north after midnight through
Thursday morning. Well above normal low temps tonight near 70 with
cloudy skies and scattered precip.
Rain chances linger through Thursday with trough/weak low offshore
and persisting low level onshore flow. Closed upper low continues to
move north across the Midwest before opening into a wave Thursday
night as it approaches the Great Lakes. This will turn flow aloft to
westerly and dries out the mid and upper levels. Better chance for
scattered thunderstorms Thursday with daytime heating. High temps
around 80-82. Rain chances decrease Thursday night, but remain in
the slight chance range, with lows in the upper 60s.
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Very unsettled weather this period with SW flow aloft around upper
low moving into Great Lakes and surface/low level flow onshore and
moisture-laden. And while the chance for rain will be ever present
there is no forcing for it to ever be very heavy. The antecedent
ridge will lead to one last mild afternoon, while extensive cloud
cover will keep nighttime lows quite elevated.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
An uncertain forecast on Saturday. Upper trough axis to swing
through arguing for a drying trend while possible tropical or hybrid
low off the coast-its position uncertain and thus how far west it
manages to fling moisture. More certain drying slated for Sunday as
the upper wave continues east and the offshore low accelerates away
from the area. Mid level ridge will build for the remainder of the
period keeping the area dry and bringing a slight warming trend.
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR conditions will continue into the first part of Thu before
ceilings start to drop. Increase in low level moisture and
isentropic lift helps spread a lower cloud deck over the area.
Inland areas will flirt with IFR by daybreak while along the
coast 1500 to 2000 ft seems more likely. Ceilings start to lift
by mid-morning and could see breaks in the the deck by early
afternoon as the bulk of the moisture shifts off to the north.
Winds will remain out of the northeast with speeds generally
under 10 kt.
Extended Outlook...MVFR conditions could develop in
association with clouds and multiple rounds of showers through
the end of the week.
Through Thursday Night...While not at advisory levels, marine
conditions this evening into overnight will be a bit rough.
Northeast winds 15-20 kts, occasional gusts to 25 kt, and seas 3-4
ft with 5 footers in outer coastal waters. Conditions improve before
sunrise tomorrow morning with the pinched gradient relaxing as a
tropical wave approaches from the south. ENE winds Thursday and
Thursday night generally 10-15 kts with seas 3-4 ft. Seas will
be a mix of a 7-8 sec SE swell and a 2 ft NE wind wave. Best
chance for showers and thunderstorms over coastal waters will be
Friday through Monday...Winds to be out of the N to NE for the
entire period. High pressure passing by well to our north will be
the primary wind-maker. A weak and small low well offshore will make
a contribution as well, but tend to stay far enough offshore to
bring any increase in speeds. Seas will tend to build as time wears
on both as the NE fetch becomes more and more established and a
small easterly swell component materializes.
Combination of a new moon this morning and persistent onshore
flow will contribute to coastal flooding risk through end of the
week. Along the Lower Cape Fear River at Downtown Wilmington,
coastal flooding is forecasted with each high tide through at
least Friday. Morning high tides will be the higher of the two,
with the evening high tides currently forecasted right at 5.5`.
For the beaches, New Hanover and Pender county beaches are
forecasted to experience minor coastal flooding Thursday and
Friday mornings, with southern beaches going over Friday
NC...High Rip Current Risk from 6 AM EDT Thursday through Thursday
evening for NCZ106-108.
Coastal Flood Advisory until midnight EDT tonight for NCZ107.
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
657 PM CDT Wed Oct 6 2021
.SHORT TERM...(This evening through Thursday night)
Issued at 252 PM CDT Wed Oct 6 2021
The stratus deck that moved up from the southeast this morning is
narrowing and where the sun has been able to come out CU fields have
developed. The NBM was pretty aggressive in reducing cloud cover
overnight, so in coordination with neighboring offices we bumped up
the cloud coverage overnight. An upper low will move north out of
the Arkansas/Missouri area, more or less tracking along the
Mississippi River, and advect deeper moisture into our forecast
area. This will bring the chance for isolated to scattered showers
tomorrow. Reduced the PoPs a bit for tomorrow as the NBM PoPs looked
overdone. Rainfall totals look to be quite light with only a few
hundredths, to perhaps a tenth of an inch. The best chance for any
showers will be in eastern Minnesota and west central Wisconsin.
There is some CAPE in the forecast, so some thunder is possible,
particularly in southern Minnesota. Clouds overnight should keep the
threat of fog pretty minimal. The chance for showers will continue
into Thursday evening before winding down overnight as the upper low
gets caught up in the southwest flow aloft and begins tracking more
to the northeast.
Not much change in temperatures through the short term. Highs
tomorrow will be mainly in the low to mid 70s with the warmest
temperatures in western Minnesota. Lows tonight will fall into the
50s, to around 60 in the Metro area, with clouds increasing. Low
temperatures tomorrow night will be similar, perhaps a degree or two
.LONG TERM...(Friday through Wednesday)
Issued at 252 PM CDT Wed Oct 6 2021
The already above normal temperatures are forecast to climb even
more Friday into Saturday as a thermal ridge builds into the Central
Plains from the southwest. Highs Friday and Saturday are forecast in
the mid to upper 70s, with a chance of isolated 80s. In fact, the
deterministic ECWMF and GFS show MSP reaching 80 at least one day to
end the week. Lows Friday and Saturday night will be in the mid to
upper 50s, with the Twin Cities heat island remaining slightly
warmer. Showers are possible across our eastern CWA Friday afternoon
as a weak, cutoff low over the Mississippi River Valley slowly
meanders northward. This disturbance will eventually make its way
into the Great Lakes before getting caught up in the upper-level
flow and traveling east.
Meanwhile, our next good chance of precip looks to be Saturday into
Sunday as a vorticity maximum associated with a positively tilted
trough over CA/NV breaks off and travels northeast into the Northern
Plains. A strong, 140 knot southwesterly jetstreak ahead of the
vorticity max should allow for a deepening surface low, moving from
the Dakotas across northern MN into Sunday night. Guidance favors
the heaviest area of precip along the northern periphery of the low
near the warm front and deformation zone. To the south, the moisture
profile in the low to mid-levels is drier causing models to be more
stingy with rain. As such, NBM has likely to definite PoPs across
northern MN, decreasing to chance then slight chance PoPs as one
goes south to southern MN. QPF amounts follow the same regime with
perhaps our northern MN counties nearing an inch total for the
weekend. Guidance does hint multiple inches across northwest MN; an
area that desperately needs rain.
Heading into early next week, models amplify a vast upper-level
ridge across eastern North America in response to strong low-level
WAA. The placement and strength of this ridge should act to steer
any future systems northward as they enter the central CONUS.
Indeed, another chance of rain is possible across the Upper Midwest
Monday into Monday night as the remainder of the aforementioned
CA/NV trough finally ejects east of the Rockies. Following this
system is when things could get really interesting. A strong upper-
level jetstreak is forecast to dive south along the west coast
Monday, highly amplifying a trough over the western CONUS by Monday
night. Long range models show this trough crossing the Rockies and
ejecting northeast into the Northern Plains by mid-next week. While
timing and placement uncertainty exists, ensembles and deterministic
guidance seem to agree that there will be a strong low and surface
cyclone affecting some part of the north-central CONUS Wednesday
into Thursday. Thus, our first strong low pressure system for the
Fall season could be on the horizon. Temperatures for next week are
forecast to cool but still remain slightly above normal for early to
mid October (normal highs are in the lower 60s while lows are in the
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 657 PM CDT Wed Oct 6 2021
The biggest issue this period surrounds around MVFR stratus
timing/extent on Thursday. Trends for precip are on a downward
direction for the day on Thursday, but increasing Thursday evening
(after this period for all but MSP). For the stratus, favored the
more conservative GFS for bringing it in and how far northwest to
take it. This did delay when MN terminals see the stratus and we
introduced it into WI as well. RAP/HRRR are a bit more aggressive
with the stratus for both bringing it in earlier and spreading it
across all MPX terminals, so continued modifications to the cig
forecast are likely.
KMSP...RAP shows stratus moving into MSP as early as 11z and quite a
bit lower (IFR) than the GFS. However, with the sub-VFR stratus
currently just a narrow east-west band of MVFR cigs from the Quad
Cities to Chicago, not confident enough in the RAP to go that
/OUTLOOK FOR KMSP/
Fri...VFR. Wind S 5-10 kts.
Sat...VFR. Chc MVFR/-SHRA. Wind SE 15G25 kts.
Sun...VFR. Chc MVFR/-SHRA. Wind W 10-15 kts.
Area Forecast Discussion
National Weather Service Nashville TN
1048 PM CDT Wed Oct 6 2021
FOR EVENING DISCUSSION.
Allowed the Tornado Watch to expire as scheduled at 10pm, and have
continued the Flash Flood Watch through 7am as previously issued.
Latest radar imagery shows numerous showers and storms continue
across the area, mainly the eastern half of the cwa, with numerous
flash flood warnings and flood advisories ongoing. Although
showers and storms will gradually diminish in coverage overnight
per latest HRRR model runs, any additional rainfall could cause
flooding - especially in the watch area where radar estimates show
1 to over 6 inches of rain has fallen today. Instability has
diminished across the area so the threat for severe weather and
brief tornadoes has decreased, but cannot rule out a strong storm
or two. Have updated grids and zones based on latest radar trends
and short term models.
00Z TAF DISCUSSION.
Upper level impulse will work northward this evening across
primarily the eastern half of the mid state. Airmass is rather
unstable and strong to severe storm potential will remain for CSV
through 03Z. Aft 03Z, showers to continue through at least 08Z to
10Z. Elsewhere, western and central middle TN taf sites will lean
toward NSW aft 06Z. Across the east, convective coverage should
begin to decrease late tonight with this trend continuing into the
day on Thursday.
Flash Flood Watch until 7 AM CDT Thursday for Bedford-Coffee-