Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/11/20

Area Forecast Discussion

National Weather Service Bismarck ND

853 PM CDT Tue Mar 10 2020

.UPDATE...
Issued at 853 PM CDT Tue Mar 10 2020

Fog/stratus imagery loop and surface-925mb observations show a
weak low circulation between Bismarck and Flasher. High
resolution models still forecasting stratus and patchy fog to
evolve between Bismarck and into the James River Valley 04z-09z.
Satellite indicates a developing area of stratus/patchy fog from
Wishek to Ashley, and looking at webcams at both locations, it
appears that this is indeed developing. Will add some mention of
patchy fog, although it will remain progressive in nature per
HRRR/RAP/GFSLamp guidance. As mentioned, the stratus and fog will
be exiting by 09z as warm air advection/vertical motion increase
along with westerly winds just above ground level. All of these
elements will promote drying conditions through the low level
column. Otherwise, warm air advection west with cirrus
overspreading western and central North Dakota will continue for
the rest of tonight.

UPDATE Issued at 548 PM CDT Tue Mar 10 2020

Latest radar and water vapor imagery loop shows a weakening
shortwave over south central North Dakota, approaching the James
River Valley. As expected, lightning has been decreasing over the
last hour. Will continue to monitor this as it shifts east this
evening. Low clouds over northeastern South Dakota are forecast
to move into and through the James River Valley early tonight,
from 04z-09z. Current forecast looks good.

.SHORT TERM...(This evening through Wednesday)
Issued at 237 PM CDT Tue Mar 10 2020

The main concern in the near term is scattered rain/snow showers and
the potential for isolated thunderstorms across south central North
Dakota this afternoon and evening.

An upper level trough is passing through the Northern Plains this
afternoon, with low level warm air advection underneath. This
forcing has led to scattered showers across western into south
central North Dakota this morning and early afternoon. This snow has
been much heavier and longer lasting than expected. We received
reports of around 2 to nearly 4 inches from near Grassy Butte to
Killdeer. As of 215 PM CDT, the precipitation was centered near Lake
Sakakawea. While downstream surface temperatures are near 40,
dewpoints are still around 30, so think that a wet-bulb effect could
cool temperatures enough for precipitation to remain mostly snow.
Confidence on how long this snow will continue and remain impactful
is very low.

Further south, satellite and radar show scattered showers developing
along and south of Interstate 94. Multiple consecutive runs of the
RAP have shown CAPE approaching 500 J/kg nearly overlapping with 40
kts of 0-6 km bulk shear in an area enclosed by Highway 85,
Interstate 94, the Missouri River, and the South Dakota border.
Therefore, it seems reasonable that these showers may evolve into
isolated thunderstorms through the afternoon. Regardless of whether
these showers contain lightning, BUFKIT momentum transfer suggests
gusty winds as high as 45 mph accompanying the showers. This
activity is forecast to dissipate this evening as it enters a more
stable air mass east of the Missouri River. There could be a change
over back to snow before the precipitation completely ends, with
little to no impacts expected.

A light southwesterly breeze and at least scattered cloud cover will
keep temperatures warmer tonight, with much of western and central
North Dakota seeing lows in the lower to mid 30s. Some models are
suggesting fog development from south central into eastern North
Dakota tonight, but winds just above the surface seem a bit too
strong, so will leave this out of the forecast for now.

For much of Wednesday, western and central North Dakota will be
under the warm sector of a clipper system moving from central
Saskatchewan into southern Manitoba. Most areas outside the James
River Valley and Turtle Mountains will see highs in the 50s. Models
have trended farther south with this system and have sped up the
cold front arrival in northwest North Dakota to as early as mid
afternoon. There could be some rain showers along the cold front as
it moves through. Also, expect breezy conditions on Wednesday.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 237 PM CDT Tue Mar 10 2020

The main concern for the long term period is increasing chances for
accumulating snow this weekend.

By the middle of the night Wednesday, the cold front will have moved
through the area. Thursday will be cooler, with highs mainly in the
30s. Some models are suggesting the potential for flurries mainly
across northern North Dakota on Thursday under cyclonic flow aloft,
but the probability is not high enough to include in the forecast at
this time. Colder air will continue to filter into the region on
Friday, ushering in a prolonged period of weather more typical of
winter.

The main feature of concern is a strong closed upper low that is
forecast to land on the Pacific Northwest coast by Friday night.
Downstream strong isentropic ascent in tangent with right entrance
region jet dynamics is forecast to result in snow developing across
western North Dakota as early as late Friday night. What happens
beyond this remains unclear. The GFS and ECMWF are persistent in
showing different solutions through early next week, and their
respective ensembles support the deterministic solutions. The GFS
shows a stronger, more progressive wave bringing several inches of
snow to much of western and central North Dakota. Meanwhile, the
ECMWF is slower and weaker, and even advisory level snow is in
question. What is becoming more certain is that it will snow
somewhere at some point this weekend into early next week. But
details on how much, exactly when and where, and the degree of
impacts remain very uncertain at this time.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 548 PM CDT Tue Mar 10 2020

LIFR cigs are expected at KJMS between 04z-09z Wednesday,otherwise
VFR cigs/vsbys are forecast for the remaining terminals this taf
period. Low-level wind shear at or below 1000ft above ground level
has been added to all terminals except KMOT. This is associated
with a warm front that will mostly impact KXWA/KDIK/KBIS between
09z-17z Wednesday, and KJMS from 21z through the end of the
period.

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

UPDATE...KS
SHORT TERM...Hollan
LONG TERM...Hollan
AVIATION...KS

Area Forecast Discussion

National Weather Service Charleston SC

900 PM EDT Tue Mar 10 2020

.SYNOPSIS...
High pressure will persist offshore into late week. A cold
front could move into the region Friday night before stalling
over the weekend.

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
No major changes were made for the mid-evening update. Both the
RAP and H3R keep a risk for isolated showers lingering for much
of the night, but both have been too aggressive in their
respective simulated reflectivity products so far tonight.
11/00z CHS raob depicted a rather dry profile with PWATS less
than an inch. Gridded pops 5-10% look reasonable for now. Lows
in the mid- upper 50s look on track.

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: There is decent model agreement that an advancing mid
level short wave will intercept an axis of modest instability (both
surface-based and mid level). This should result in scattered
showers and a few tstms developing across inland zones during the
afternoon. These convective rains will sweep into the coastal zones
by late day or early evening and offshore Wednesday night. Higher
rain chances appear to be north of I-16 and mostly across Southeast
SC. We see mixed signals for any risk of severe tstms, however very
dry layers above 700 MB and chances for ML CAPES exceeding 500 J/KG
are both on the low side, suggesting severe convection is unlikely.
The GFS was an outlier on the 12Z/10 model run with higher deep-
layered instability and greater convective QPF. We bumped POPs into
the 40 percent range along our northern tier of zones. Highs will be
warm in the mid 70s north to around 80 south with partly cloudy
skies.

Thursday and Friday: A warm and moist airmass will remain in place
during the period as high pressure lingers offshore. Occasional weak
shortwaves will move through Thursday into Friday, potentially
producing isolated showers at times. Highs should continue to warm
with Friday likely the warmer day ahead of backdoor cold front on
Friday night. We nudged highs up to around 80 north to almost the
mid 80s to the south of I-16 in GA.

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A backdoor cold front will approach the area late Friday afternoon,
stalling over or just south of the area through early next week.
Slightly cooler temps and better rain chances are expected.

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
VFR.

Extended Aviation Outlook: Localized risk for flight restrictions as
convective rains move through the coastal corridor late Wednesday
and Wednesday Evening. Patchy low clouds and fog possible Thursday
morning and perhaps low cigs in the wake of a backdoor cold front
this weekend.

.MARINE...
Tonight: High pressure offshore will lead to mainly S to SW
winds around 10 kt. Seas will be in the 2-4 ft range, possibly
as high as 5 ft in the far out reaches of the Georgia offshore
waters late.

A S to SW flow will persist Wednesday through Friday. SCA conditions
are not expected during the time period across near shore waters. We
could see a brief period of 6 ft seas closer to the Gulf Stream
Wednesday Night over outer GA waters. Models are still divergent in
the progress of the backdoor cold front Friday night into the
weekend. Some NE surging is possible over South Carolina waters
during this period and we may end up seeing some SCAs during latter
periods.

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

Area Forecast Discussion

National Weather Service Cheyenne WY

916 PM MDT Tue Mar 10 2020

.UPDATE...
Issued at 911 PM MDT Tue Mar 10 2020

Since wind speeds have decreased across Central Laramie County,
including Cheyenne, we have decided to cancel the High Wind
Warning there a few hours early. The rest of the High Wind
Warnings will continue.

.SHORT TERM...(This evening through Wednesday)
Issued at 218 PM MDT Tue Mar 10 2020

A westerly flow aloft with a few shortwaves embedded within the
flow and minimal surface instability has lead to a breezy, warm day,
with a few clouds overhead, and some light showers and a lightning
strike or two over the southern Panhandle. A few light snow showers
over the mountains west of the Laramie Range are still possible, but
will decrease in probability over the next few hours and taper off
this evening. Have seen an increase in subsidence aloft that has
allowed for strong winds at 700 mb to mix down to the surface for
windy conditions across the High PLains and through the gap wind
ares of southeast Wyoming. As winds increased this morning and
looked to overachieve, issued a High Wind Warning for the wind-prone
areas, and expanded it into central Laramie County, mainly to
capture the northern area of the county, where Bear Creek has been
gusting close to High Wind criteria for a few hours. Across the High
PLains, also saw temperatures rise a few degrees over the forecasted
high, and minimum humidities drop more than expected due to winds
coming off of the Laramie Range, causing compressional heating for
areas along and east of the I-25 corridor.

With this in mind, and knowing that a northern clipper is expected
to descend out of the north tomorrow for increased surface
gradients and therefore stronger winds at the surface, have issued
the HIgh Wind Warning out through Thursday morning for all zones
included in the Warning today, except for the central Laramie
County zone. Also, winds will gust up to 30 mph across the
Panhandle, with low humidities - achieving Red Flag Warning
criteria across the western Panhandle for the afternoon period,
where all fire weather zones have been converted to "ready." This
means that any fires started tomorrow across the Panhandle may
spread quickly and be difficult to put out.

Meanwhile, to the west of the Laramie Range, the clipper will
draw moisture out of the southwest once more, and a wintry mix of
rain and snow is expected to fall across the Sierra Madre and
Snowy MOuntains, in addition to the lower elevations of Carbon
County. Precipitation will be light with only an inch or two of
accumulation possible over the peaks. The wintry mix will limit
this accumulation however. As the disturbance descends south over
the High Plains, will see the wintry mix fall across the region as
far south as a line extending from Converse County out through
Dawes County, including the North Laramie Range and its foothills
to the east, by daylight Thursday morning. The High Wind Warning
will end around this time as gradients shift and subsidence gets
cut-off.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 218 PM MDT Tue Mar 10 2020

A passing cold front exiting the forecast area by Thursday morning
will bring a chance of light snow across mainly the northern half of
the CWA as lighter accumulations of up to an inch across the high
plains may be possible. This snow will likely not linger too long as
daytime highs on Thursday reach into the upper 30s and low 40s and
given the recent warm temps and lack of overall support for heavy
snowfall rates not overly concern with any prospective headlines at
this time.

Focus quickly turns to Friday as an upper level closed low gets
absorbed in the overall troughing pattern. This amplified wave will
then eject eastward as precipitation chances increase through Friday
afternoon into Sunday. Moisture transport from the Gulf of
California should provide decent atmospheric profile saturation that
will enable further dendritic growth aloft and subsequent snowfall
amounts. Given the progressive nature of the system and how the EURO
and GFS have the wave impacts reach our area still remains somewhat
disjointed. Given the slight disconnect, concern moving into the
weekend will be where the heavier snowbands occur along with the
transition of the rain/snow line as some wintry mix cannot be ruled
out completely. This forecast for the weekend will need to be
watched as we get closer due to any prospective impacts to area
travelers across both states and snow/ice concerns.

Moving into the tail end of the weekend, broad pacific coast trough
pattern sets up with embedded waves following the atmospheric flow
with multiple rounds of light to moderate precipitation chances
possible along with cooler Canadian air settling in for a perhaps
dreary, cooler string of days to start the week.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 516 PM MDT Tue Mar 10 2020

Lingering showers on the latest KCYS radar are moving away from
KSNY as breezy winds become the main story through the overnight
and majority of Wednesday. CONSSHORT picking up on some LLWS from
KSNY through KLAR overnight while the RAP, GFS, and HRRR are
picking up on stronger winds aloft though soundings have it still
fairly gradual in rise. Have bumped up winds at terminals
overnight and into Wednesday with gusts into the mid 30 kt range.

.FIRE WEATHER...
Issued at 218 PM MDT Tue Mar 10 2020

Gusty westerly winds coming off the Laramie Range have
contributed to warmer temperatures, and lower humidities today
than previously forecast. As winds overachieved and mixed down
from aloft, a High Wind Watch was upgraded to a Warning and
expanded to other zones. This is a sneak peak of what we expect to
see tomorrow as a stronger system moves out of the north
tomorrow, with increased winds, and therefore, lower humidities,
and higher gusts forecast for WEdnesday afternoon. High
temperatures will also increase. Have issued a Red Flag Warning
for Wednesday afternoon to cover the threat as fuels are now
ready across the western Panhandle. Will see a pattern change and
increased humidities and lowered temps towards the end of the week
and into the weekend.

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 AM MDT Thursday for WYZ106-110-116-117.

NE...Red Flag Warning from noon to 7 PM MDT Wednesday for NEZ311>313.

UPDATE...RUBIN
SHORT TERM...AB
LONG TERM...WM
AVIATION...WM
FIRE WEATHER...AB

Area Forecast Discussion

National Weather Service Dodge City KS

648 PM CDT Tue Mar 10 2020

...Updated Aviation Section...

.SHORT TERM...(This afternoon through Wednesday night)
Issued at 1145 AM CDT Tue Mar 10 2020

Remaining stratus is eroding rapidly as of midday, leaving only
scattered cirrus embedded in the westerly zonal flow aloft. A
pleasant early spring afternoon, warming into the 60s east and 70s
southwest, with modestly breezy south winds. Winds will trend light
SEly by early evening, with NAM/HRRR agreement placing a surface low
near Boise City, Oklahoma.

A shortwave will dive through Kansas tonight. 12z NAM, HRRR and
various other CAMs are in excellent agreement forecasting
scattered convective development across the NE/east zones late
this evening through midnight. NAM forecasts a modest instability
axis across these zones by late this evening, with MUCAPE to near
500 J/kg near Larned ranging up to 1500 J/kg in the Barber county
vicinity. Surface moisture quality will be limited, typical of
early March, with dewpoints generally in the mid 40s. Yet, steep
mid level lapse rates and dynamic lift ahead of the arriving
shortwave yield high confidence in convective development. Shear
will support primarily elevated, weakly rotating updrafts, capable
of hail to the size of dimes to quarters. Included thunderstorms
in the grids from Hays to Larned, St. John to Pratt to Medicine
Lodge. Convection will initiate near the eastern CWA border, but
confident any convective organization will be relegated to
Wichita`s CWA zones late tonight. Marginal 5% hail probability
from SPC is warranted. A northerly wind shift/cold front will
progress southward across SW KS tonight behind the departing
shortwave, with gusts of 25-30 mph. These northerly winds will be
very brief in duration, with winds trending light and variable
around sunrise Wednesday. Sunrise Wednesday temperatures ranging
from mid 30s north to mid 40s south.

Wednesday will feature near-perfect spring weather, with mild
temperatures and light winds beneath benign zonal flow aloft. All
locations will warm to within a few degrees of 70 with a mix of
sunshine and cirrus. Get outdoors and enjoy!

Models depict another very weak shortwave Wednesday night/early
Thursday, with an increase in cloud cover and the potential for
additional rain showers favoring the eastern zones. Milder
temperatures Thursday morning, holding in the 40s.

.LONG TERM...(Thursday through Tuesday)
Issued at 209 PM CDT Tue Mar 10 2020

Despite a pronounced shift to north winds, another pleasant spring
day is expected Thursday with continued dry weather. A dry cold
front will usher in modest cooling at 850 mb, cooling temperatures
most noticeably across the northern zones, with far northern zones
holding in the upper 50s, still near 70 along the Oklahoma border.

A big change to cloudy and much cooler on Friday. Strong closed
low over southern California 7 am Friday will weaken to a
negatively-tilted progressive trough near the Four Corners 7 pm
Friday. As this weakening system approaches, energizing SW flow
aloft will send copious Pacific moisture over the plains, with a
thick overcast expected. Simultaneously, broad cool surface high
pressure across the northern/central plains will continue to push
a much cooler airmass into SW KS, with a pronounced easterly,
increasingly moist upslope boundary layer flow. Between these two
mechanisms, clouds will be extensive Friday. 12z ECMWF shows
pronounced 850 mb cooling, trimming to near 0C at 850 mb at DDC
Friday afternoon. With no sun, afternoon temperatures will
struggle in the lower to mid 40s.

High confidence regarding a significant round of precipitation,
centered on Friday evening. Models continue to show strong
dynamic lift overspreading SW KS Friday evening, ahead of the
approaching shortwave trough axis. Plentiful Pacific moisture will
combine with an open gulf, generating widespread measurable
rainfall. Today`s run of the NBM came in very wet, with widespread
90% pop grids. These were accepted, with 12z ECMWF depicting
strong QPF signals across all zones Friday evening. High
confidence on precipitation occurring. Some questions linger
regarding rain versus snow. NBM/GFS solutions are notably colder,
with current forecast showing rain changing to snow across the
western 1/2 of SW KS (higher terrain) Friday night. 12z ECMWF
850 mb thermal fields are warmer, and argue for mostly rain,
actually showing warm air advection into the southern zones during
the heaviest rain. This is a reverse from several runs ago, when
ECMWF was colder. All of this to say, phase change uncertainty
remains with this expected round of beneficial precipitation.
Progressive trough axis will be east of SW KS midday Saturday,
with all SW KS zones dry by Saturday afternoon.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 644 PM CDT Tue Mar 10 2020

Overall, the aviation weather will be fairly tranquil for this TAF
period. The only exception may be up at the HYS terminal late this
evening as we will be monitoring development of showers and
thunderstorms around that terminal toward 03Z. Any
showers/thunderstorms in vicinity of HYS will only last an hour or
two late this evening before pushing east deeper into central and
south central Kansas where the greater organization and strength
of thunderstorm activity will be overnight. A fast-moving front
will sweep south, providing a bump in wind speed to 12 to 15 knots
out of the north-northeast. These winds should not last long, 3 to
5 hours or so, before falling quickly down to 6 knots or less and
remaining light the remainder of the TAF period.

.PRELIMINARY POINT TEMPS/POPS...
DDC 41 70 46 65 / 10 0 10 0
GCK 38 70 44 64 / 10 0 10 0
EHA 42 69 46 69 / 0 0 0 0
LBL 43 69 45 69 / 0 0 0 0
HYS 39 69 44 60 / 30 0 20 0
P28 45 70 49 70 / 50 0 10 0

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Umscheid

AREA FORECAST DISCUSSION

National Weather Service Eureka CA

355 PM PDT Tue Mar 10 2020

.SYNOPSIS...Warm and dry conditions will continue through Friday
afternoon, with well above normal interior temperatures expected.
Cooler, showery conditions are expected over the weekend, with
accumulating snow possible along many travel corridors as well.

.DISCUSSION...High pressure has reclaimed California, and as a
result, warm and dry conditions with mostly sunny skies can be
expected through at least Thursday, and possibly Friday as well.
Interior locations are likely to see high temperatures climbing
into the 70s and perhaps near 80 in some parts of Mendocino
County each day, with temperatures inching toward 60 along the
coast. Overnight, while temperatures will gradually begin to
increase through the week, efficient radiational cooling will
likely mean that interior valleys will continue to be chilly,
with patchy frost likely as well. Another frost advisory has been
issued for tonight and Wednesday morning across portions of
northern Mendocino and northern Lake Counties as a result.

Friday is expected to be mostly warm and dry as well, although a
very slight cooldown is likely as a storm system is expected to
approach the area from the north. Model guidance appears to be
converging on a more common solution for this storm, which will bring
much cooler air and showers to the region Friday night through at
least Sunday, and possibly Monday. While confidence is high that
much cooler temperatures are expected, and that precipitation is
not expected to be particularly heavy from a liquid perspective,
there is considerable uncertainty regarding how much snow will
fall and at what elevations. However, there is potential to see
snow falling as low as 1500 feet in elevation by Saturday, which
would impact numerous local highway passes over the weekend. In
addition, convective showers may also be capable of producing
accumulating small hail. This showery, unsettled weather is likely
to continue through late Sunday, and may linger into Monday if
the storm system is slow to exit to the south. /BRC

.AVIATION...Mostly VFR conditions are expected to prevail across
the area over the next 24 hours. The one fly in the ointment is
the possibility of some low ceilings around the Humboldt Bay area
prior to daybreak Wednesday as indicated by the high resolution
HRRR model. Although there is no indication of clouds in these
areas as yet, it is possible due to low-level moisture pooling
along the coastal terrain N of Cape Mendocino. Is is uncertain
whether any ceilings would fill in over KACV, so have included a
scattered low deck for now. The combination of dry air and light
offshore flow overnight should keep visibilities mostly VFR at
coastal TAF sites, and there is no indication of any low clouds
creeping up the Russian River Valley into KUKI. Some afternoon and
evening wind gusts to near 20 knots are possible today along the
Redwood Coast, particularly at KCEC. Otherwise, low-level winds
over land are expected to be generally light. /SEC

.MARINE...Northerly winds and seas will continue to trend upward
this evening as the coastal pressure gradient tightens in response
to high pressure building offshore. Small Craft Advisory conditions
over the offshore zones will expand to the nearshore waters north of
Cape Mendocino this evening as seas continue to build and propagate
into the inner waters. The southern nearshore zone will likely
remain a bit more sheltered over the next few days, precluding the
need for an advisory at this time. However, localized strong winds
and rougher seas will likely still be found in the typical locations
near and downwind of the Cape. Have went ahead with Gale Warning
for the northern outer waters for Wednesday afternoon as recent
guidance has trended a bit stronger with winds over the next few
days. The small craft advisory for the northern inner waters may
need to be extended if the trend holds. Seas will be dominated by
wind-driven, short-period waves which will likely rise above 10
feet by later Wednesday given the duration of the northerly wind
regime. Multiple small swells will also move through the waters in
the next few days, including a long-period S swell of about 2 ft
and a pair of mid-period NW swells on the order of 3-4 ft. Expect
a brief break in the northerly regime this weekend as the next
system approaches from the northwest, although seas will likely be
slower to come down.

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Frost Advisory from 1 AM to 9 AM PDT Wednesday for CAZ110-111-
114.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 PM PDT Wednesday for PZZ470.

Gale Warning from 3 PM Wednesday to 4 AM PDT Friday for PZZ470.

Small Craft Advisory until 9 PM PDT Thursday for PZZ450.

Small Craft Advisory until 9 PM PDT Thursday for PZZ475.

Visit us at https://www.weather.gov/eureka

For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png

Area Forecast Discussion

National Weather Service Fort Worth TX

701 PM CDT Tue Mar 10 2020

.SHORT TERM... /NEW/
/Through Wednesday Evening/

Afternoon surface analysis reveals a 1016 mb low over the Nebraska
Sandhills, with a broad warm sector south of this low across much
of the Southern Plains. Dewpoints have surged into the 60s across
much of our CWA. DFW Airport recorded a high temperature of 80 F
this afternoon, making today the warmest day since February 2,
2020 when the high reached 81 F. Waco on the other hand, only
reached a high of 73 F as cloud cover persisted for much of the
afternoon.

Tonight, we will see temperatures dropping into the mid 60s. Light
winds, temperatures cooling to near their dewpoints, and
subsidence aloft will favor the development of areas of fog,
particularly across Central Texas. A Dense Fog Advisory may be
required again tonight in our southern two or three tiers of
counties. For now, will wait on the next round of high-resolution
model guidance, but portions of Central Texas look like they`ll
probably see visibility low enough to necessitate an advisory. Fog
and low clouds should lift gradually during the morning hours,
but cloudy skies will likely persist into the afternoon.

Late in the afternoon, there is a significant amount of
uncertainty with regards to convective potential. A few of the
high-resolution models (most notably the HRRR) develop isolated to
widely scattered thunderstorms across parts of North Texas,
including in and around the Dallas/Fort Worth Metropolitan Area.
Other models keep the modest cap in place and develop nothing at
all. Backing up and looking at the bigger picture, upper-level
support will be limited at best. Despite this, we will have a weak
cold front sliding into North Texas during the late afternoon.
This front could provide enough low-level convergence and ascent
to kick off a few thunderstorms, much like the HRRR is suggesting.
For this reason, opted to include slight chance to chance PoPs,
with the highest PoPs indicated near and northeast of Fort Worth.
In terms of severe potential, this is obviously highly conditional
on thunderstorms developing in the first place. Should
thunderstorms develop, steep mid-level lapse rates and surface
dewpoints in the mid to upper 60s will support CAPE values of
1,000 to 2,000 J/kg. In addition, moderate deep-layer wind shear
on the order of 40-50 KT will be present. This parameter space
would permit whatever thunderstorms that do manage to develop to
become strong to severe, with large hail and gusty outflow winds
being the primary hazards. The cold front should dissipate over
North Texas and retreat north as a warm front late in the evening,
decreasing shower/thunderstorm chances.

The bottom line for Wednesday afternoon and evening is that
thunderstorms are not very likely. If thunderstorms do develop
however, they may be able to become severe, with large hail and
damaging winds being the main threats. Folks across North Texas
(particularly near and north of I-20, and near and east of I-35W)
will want to keep an eye on the weather, just in case. The most
likely time for any thunderstorms would be between the hours of 4
p.m. and 10 p.m.

Godwin

.LONG TERM... /Issued 218 PM CDT Tue Mar 10 2020/
/Wednesday Night onward/

Bottom line up front...the weather pattern across North and
Central Texas looks to remain unsettled through the weekend into
early next week. Expect period of rain showers and isolated
thunderstorms as surface cold fronts move through North Texas and
southwest flow aloft brings moisture and several shortwaves to
generate episodes of showers/isolated thunder.

The overall long range pattern and model solutions suggest that the
very large and strong upper level low near southern California will
stall and become elongated as the weekend approaches. As this
happens...the prevailing upper level flow across Texas is expected
to remain southwesterly with sufficient moisture content for showers
and isolated thunderstorms. As the southwest flow persists...the
models depict a cold front stalling across North Texas by Friday.
Showers and thunderstorms are possible Thursday afternoon/evening
with some limited potential for strong/severe storms north and
east of the DFW area. The exact location of this front will be
important with respect to precipitation as the southwesterly flow
aloft moves over the slope of the stalled front.

Another round of showers/thunderstorms associated with the next
upper level wave is expected late Sunday mainly northwest of the DFW
area and along the Red River.

The next cold front/surge moves into North Texas by Tuesday with
continued southwest flow aloft and showers/thunderstorms are
expected to continue through mid week.

.AVIATION... /NEW/
/00Z TAFs/

Concerns: MVFR CIGs, IFR vsby at KACT. Wednesday afternoon/evening
convective potential in/near D10 TRACON.

CIGs have managed to improve to VFR at KACT after cloudiness
persisted for much of the day. Expect all sites to see lowering
CIGs after 06Z, with MVFR likely to begin during the pre-dawn
hours. Areas of BR/FG are likely across parts of Central TX, with
IFR vsby likely at least intermittently at KACT. CIGs/vsby should
improve at all sites by 17Z.

Late Wednesday...isolated to widely scattered TSRA may develop
across parts of North TX. Confidence is too low to mention
explicitly in TAFs, but if TSRA do develop, most likely locations
would be near and northeast of KDFW with some impacts to the
Bonham arrival gate possible. TSRA would diminish after 04Z.

Godwin

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 64 81 66 85 60 / 0 10 30 20 50
Waco 63 80 63 84 63 / 0 10 10 10 40
Paris 61 77 63 79 57 / 0 10 30 40 70
Denton 63 81 65 85 57 / 0 10 30 20 50
McKinney 63 79 65 83 58 / 0 10 30 20 60
Dallas 64 81 66 84 60 / 0 10 20 20 50
Terrell 63 80 63 81 60 / 0 10 20 20 50
Corsicana 63 80 63 80 63 / 0 10 10 10 40
Temple 61 80 63 82 63 / 0 10 10 5 30
Mineral Wells 61 81 63 85 57 / 0 10 20 10 40

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

37/26

AREA FORECAST DISCUSSION

National Weather Service Hastings NE

959 PM CDT Tue Mar 10 2020

.UPDATE...
Issued at 959 PM CDT Tue Mar 10 2020

HRRR continues to indicate the potential for dense fog, especially
for areas along and north of a line from Minden to Geneva in
Nebraska. A Dense Fog advisory has been issued until 10am for
those locations. Some areas of freezing dense fog is possible
where temperatures may drop to 32 degrees or below.

UPDATE Issued at 642 PM CDT Tue Mar 10 2020

The HRRR and SREF guidance continues to indicate the potential for
fog tonight especially after midnight through the morning hours
Wednesday. Have taken a more bold approach on the forecast
extending it across much of the area. Right now, have not
increased it to dense fog, but the potential is definitely there.
Will continue to monitor for potential Fog headline.

.SHORT TERM...(This evening through Wednesday)
Issued at 344 PM CDT Tue Mar 10 2020

Radar shows a few returns in the far northeast part of the area yet
this afternoon. They will soon be moving out of the area. Satellite
shows a clearing line with the western part of the forecast area
with partly cloudy skies while the east is still cloudy. The
temperatures are warming up where there is a little more sunshine,
but the rest of the area remains on the cool side.

Have cooled things off a little bit for this afternoon, but expect
that the sunshine continues to spread to the east and temperatures
will warm some.

There is a weak upper level wave that moves into the area tonight.
Clouds are expected to move back into the area and some of the
models bring in some mainly spotty precipitation for the evening.
Not all of the models have precipitation and those that do have very
light or spotty precipitation for the area. Have lowered PoPs a
little, but wonder if there is more in there than will actually
happen. There will be some instability that could bring some thunder
to the area. Expect that all of the precipitation will be ending
around midnight or a little after.

The next concern will be fog. The edge of the lower deck of clouds
has been slow to move out and there could be some fog tonight. Will
go with the idea that the lower clouds will move out of the area
this afternoon/evening and will move back with some fog later
tonight. Have the fog in the northeast, but will need to see if that
is far enough. If the clouds do not move out, there may be fog
further to the west.

Fog will linger into Wednesday morning, but should move out better
during the day. With sunshine and warm advection, expect
temperatures to be warmer on Wednesday.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 344 PM CDT Tue Mar 10 2020

Wednesday night through Thursday night there is a weak wave that
will move through Wednesday night. There is a chance for there to be
some light rain late Wednesday night as a weak cold front moves
through the area. Thursday will be a little cooler behind the cold
front.

The period Friday through Saturday is expected to be fairly busy. A
surface high builds into the area Thursday night with colder air
building into the area ahead of an approaching upper level low. The
models continue to have differences in the timing and how the system
moves through. The ECMWF is much faster than the GFS with
precipitation across the area on Friday. It may be a little fast,
but believe that there will be something around and there will be
some time to fine tune it as it gets closer. The models are a little
closer for the Friday night into Saturday time frame that there will
be quite a bit of precipitation around the area. The next question
becomes weather type. The models still have fairly warm temperatures
during the day on Friday and Saturday, so it starts off with some
mixed rain/snow, but changes to rain during the day time, with more
of mixed or even snow during the night. The problem is, some of the
forecast highs are quite a bit higher than some of the raw model
data. Would not be surprised to see some lower temperatures as this
period gets closer.

Saturday night through Tuesday should continue to be fairly busy.
The first wave moves out and Saturday night should be dry, but
another weak wave moves in with some warm advection. Expect there to
be some precipitation with the warm advection. The temperatures will
continue to be cool enough during the night that there will be some
snow, but during the daytime there may be some rain.

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 642 PM CDT Tue Mar 10 2020

The primary aviation concern is the potential for fog tonight...some
could be dense. The HRRR and SREF guidance continues to indicate the
potential for fog tonight, especially after 06z with the potential
for some dense fog. Have really taken a pessimistic direction for
the 00z TAFs with that line of thinking. IFR conditions through the
overnight hours could become LIFR if dense fog does indeed become
reality. Confidence is increasing on this fact, but for now...I`ve
kept visibility in the IFR range. Will need to watch for amendments
and for 06z TAFs for updates.

Additionally there continues to be a chance for some showers and
thunderstorms tonight. The high-res guidance continues to indicate
that KGRI has the best potential for this to occur, so have a VCTS
in KGRI only for a couple hours this evening.

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Dense Fog Advisory from 1 AM to 10 AM CDT Wednesday for
NEZ039>041-046>049-061>064-074>077.

KS...NONE.
&&

UPDATE...Billings Wright
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...Billings Wright

Area Forecast Discussion

National Weather Service Jacksonville FL

800 PM EDT Tue Mar 10 2020

.UPDATE...Isolated showers have formed along the the west coast
seabreeze this evening as models have indicated. Expect shower
activity to dissipate before midnight with mild temperatures
overnight. Late night fog possible as clouds have decreased over
the area with passage of shortwave trough aloft.

.AVIATION...VFR conditions will prevail tonight and Wednesday.
Patchy fog possible over inland ne Fl between 08z-12z at GNV and
VQQ may result in brief MVFR/IFR vsbys. Winds will be light from
the sw at 5-10 knots Wednesday morning...becoming se during the
afternoon near the east coast.

.PREV DISCUSSION [354 PM EDT]...

.NEAR TERM [Through Tonight]...

Atlantic sfc ridge continues to be positioned just north of the
area and will shift south and southeast through tonight. As
result, low level winds currently southeast will weaken and become
more southerly during the day. Upstream, model guidance shows a
shortwave trough over AL/central and nrn GA pushing eastward
which should reach our area later this morning and aftn. Radar
shows a swath of rain and showers associated with this trough. This
feature along with weak low level convergence will support a low
chance of showers (about 15-25 percent) for southeast GA today.
Further south, model blends, including GFS/ARW/NMM and the HRRR
suggest a few showers over inland northeast FL this aftn. A few
showers also expected offshore waters near a sfc trough. Though
mid and high clouds will be prevalent today until the early to mid
aftn hours, southerly flow will support highs in the mid to upper
70s, with coastal areas being limited to lower to mid 70s due to
onshore flow.

Tonight, shortwave trough is expected to push offshore of our
coast while multilayered clouds continue into the evening hours.
With lack of meaningful forcing for showers, will go back to POPs
of around 5-10 percent tonight. Also, anticipate an improvement in
cloud cover overnight. Lows again will drop toward the mid and
upper 50s. Some patchy fog will be possible inland northeast FL
zones.

.SHORT TERM [Wednesday Through Thursday Night]...

Another upper level shortwave will move aloft of the Tennessee
Valley tomorrow, reinvigorating the weak front to our north, then
moving off the east coast tomorrow night. The frontal boundary
will be close enough in proximity to our northern GA counties that
there may be some isolated showers or thunderstorms, though
widespread convection isn`t anticipated. The cold front is
expected to stall out again tomorrow night, keeping the area on
the warm side of the boundary through Thursday night. Temperatures
will peak in the low 80s both afternoons, then dip to the mid-
upper 50s at night.

.LONG TERM [Friday Through Tuesday]...

Mid and upper level ridging will build over the northern Gulf
coast and southeastern CONUS Friday, bumping the stalled frontal
boundary across central AL-GA northward a bit. Meanwhile, a
potent upper level +PV anomaly will move into the desert southwest
Friday, then race northeastward into the Plains Saturday,
weakening as it lifts into the Tennessee Valley Saturday night.
This more potent system will launch a front across the Plains and
into the Tennessee Valley, but keep storms to mostly to our
north, with only a 20-30% chance of storms around Monday for
southeast Georgia. The mid and upper level ridging will build over
the Florida Peninsula around mid week, with low level ridging to
our east keeping the area under light southerly flow. Daytime
temperatures will be toasty, peaking in the mid 80s, with upper
80s possible in north-central Florida. Lows will be in the upper
50s to low 60s.

.AVIATION...
[Through 18Z Wednesday]

VFR conditions expected through today with abundant passing mid
and high clouds with only brief restrictions to MVFR possible at
times under diurnally driven cumulus field. Prevailing SE winds
will continue near 10 kts or less with the potential gusts near
15 kts along coastal terminals this afternoon with east coast sea
breeze. Best potential for afternoon showers will be near SGJ and
later afternoon into the evening near GNV where sea breezes will
merge. Winds decouple this evening with lingering low clouds.
Potential for restrictions tonight after 06z due to low stratus
and fog with highest probabilities near GNV and VQQ at this time
where trended toward IFR at GNV and MVFR at VQQ after 08-09z.
After sunrise Wed, prevailing VFR with SSW winds increasing to 4-8
kts under low/mid clouds.

.MARINE...

An approaching weak cold front will stall to our north tomorrow,
with a ridge of high pressure sitting off to our northwest. This
will keep light winds from the south and low seas in place
through much of the period. This weekend, another cold front is
poised to approach the region, though at this time, winds are
expected to remain below 15 knots.

.FIRE WEATHER...

A cold front approaching the area today will stall out to our north
tomorrow, keeping a warm, humid air mass in place for the next few
days. Afternoon RH values will only dip to around 40% for the
next several days, precluding any red flag conditions. With the
front in closer proximity tomorrow, transport winds will increase
in GA, leading to high dispersions Wednesday afternoon.

.HYDROLOGY...

River flooding will continue to impact most mainstream basins
across SE GA this week. Moderate flooding will continue along the
Altamaha from Charlotteville to Everett City. Everett City has
reached a broad crest today of 16.6 ft, which the second highest
on record (at less than .2 ft shy of the highest record) and only
.4 ft shy of Major flood. The Satilla in Waycross (in Moderate
flood) is falling to Minor this afternoon while the Satilla at
Atkinson is in Minor flood and approaching its crest.

Big forecast changes for Alapaha near Statenville which was in
Action stage early this morning, with this location forecast to
rapidly rise late this week (Fri Mar 13) to Major flood.
Interests in the Alapaha basin should very closely monitor river
forecasts this week. Significant rainfall is not expected, river
levels are runoff from rainfall that occurred over central GA last
week.

.PRELIMINARY POINT TEMPS/POPS...

AMG 57 78 58 80 58 / 10 20 10 0 0
SSI 57 72 59 73 59 / 10 10 10 0 0
JAX 58 80 59 82 59 / 10 10 10 0 0
SGJ 59 77 58 79 59 / 10 20 0 0 0
GNV 57 81 55 83 57 / 20 10 0 0 0
OCF 59 80 56 83 58 / 20 20 0 0 0

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 3 AM EDT Wednesday for Coastal
Flagler-Coastal St. Johns.

GA...None.
AM...None.
&&

Area Forecast Discussion...Updated

National Weather Service Saint Louis MO

936 PM CDT Tue Mar 10 2020

.UPDATE...
Issued at 934 PM CDT Tue Mar 10 2020

Low clouds have been slow to erode across the area since sunset
and latest RAP soundings are showing moisture may stay trapped the
rest of the night under developing inversion. Going forecast was
already cloudy ahead of shortwave trough dropping southeast out
of the northern Plains. Did not change going precipitation
forecast much as there should not be much more than a few
sprinkles in the north with the shortwave trough. Still looks like
a MCS will develop over the Central Plains tonight and drop
southeast through southern Missouri into the Mid South. The
southern part of the CWA will see showers and few thunderstorms
associated with this late tonight into tomorrow morning based on
the latest RAP mass fields and the CAMS runs. Made minor
adjustments to winds and temps based on cloud changes and latest
observations.

Britt

.SHORT TERM... (Through Late Wednesday Night)
Issued at 323 PM CDT Tue Mar 10 2020

A cluster of thunderstorms is expected to develop late tonight to
the southwest of the CWA, namely over southeast Kansas and far
southwestern Missouri. This complex should head southeastward
through Wednesday morning, with the far northeastern edge of the
rain shield just clipping our far southern counties on Wednesday
morning. For the vast majority of the CWA, just an increase in cloud
cover is expected. After the morning threat of rainfall in parts of
southeast Missouri, the remainder of the day should be dry with
subsidence in the wake of the earlier midlevel disturbance. Low-
level moisture increases late Wednesday night, and combined with an
incoming shortwave trough, slight chance/chance PoPs for rain
showers are in the forecast for the late night hours.

Mild temperatures will continue through the short-term forecast
period, especially at night. Lows each night are forecast to be well
above the freezing mark, generally in the 40s. Highs on Wednesday
should be 5-10 degrees warmer than today, due to decreasing
cloudiness and low-level warm air advection. Look for temperatures
to top out in the upper 50s to mid 60s. Warmest conditions are most
likely across portions of central, east-central, and southeast
Missouri.

Gosselin

.LONG TERM... (Thursday through Next Tuesday)
Issued at 323 PM CDT Tue Mar 10 2020

(Thursday)

Chances of rain showers, and some thunderstorms, will increase ahead
of a cold front on Thursday. Currently, the best chances for rain
appear to be across east-central and southeast Missouri as well as
southwest Illinois during the afternoon where the strongest low-
level convergence and upper-level jet support is expected to reside.
There also may be a narrow temporal/spatial window for a few
strong/severe storms in some of our southeastern counties. While
deep-layer shear is quite strong, the instability is the main
question mark as models suggest below 1000 J/kg of MUCAPE. Going SPC
marginal risk looks good, and we will continue to monitor trends
with respect to instability over the next 24-36+ hours.

(Thursday Night - Friday)

A quiet period of weather is forecast to end the work week as a
strong Canadian area of high pressure at the surface slowly moves
into the Upper Midwest. Dry weather along with a return to near
normal temperatures is favored.

(Friday Night - Saturday Night)

Another round of precipitation is likely Friday night through
Saturday night. A cold rain is most likely across the area, but
am watching northern sections of the CWA for the possibility of
snow at least mixing in with the rain either or both Friday
night/Saturday morning and Saturday night when surface
temperatures are coldest. The airmass that will be in place ahead
of this system is definitely Canadian and seasonably cold/dry.
This combination should bring at least a threat of snow across
northeast Missouri and west-central Illinois, as dry air in place
helps cool the column as it saturates. Accumulations may even be
possible if the timing is just right and the snow comes down at a
heavy enough rate to coat the ground. Right now however, the best
chances are just north of the CWA as suggested by the EPS/GEFS
means. Regardless, this should not lead to any big impacts, but
is a reminder that it is mid March and winter may not be
completely over.

(Sunday - Next Tuesday)

Another short-lived quiet period is likely on Sunday as dry weather
is favored along with near to below normal temperatures.

More active weather looks to return for early next week as a deep
trough carves out across the western CONUS with a stalled baroclinic
zone somewhere across the mid-Mississippi Valley. The bottom line is
expect a wet period with several rounds of showers, and potentially
some thunderstorms. Temperatures should also moderate through the
end of the extended forecast with highs back in the 60s by next
Tuesday.

Gosselin

.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 619 PM CDT Tue Mar 10 2020

MVFR ceilings are expected to move out of the terminals between
00-02Z. Then dry and VFR conditions are expected the rest of the
period. There is some possibility of MVFR ceilings moving back
into the St. Louis area terminals late tonight into early
Wednesday, but confidence is too low to include in the TAFs at
this time. Winds will remain light through the period.

SPECIFICS FOR KSTL:

MVFR ceilings are expected to improve to VFR by 01Z. Then dry
and VFR conditions are expected the rest of the period. There is
some possibility of MVFR ceilings moving back into the terminal
late tonight into early Wednesday, but confidence is too low to
include in the TAF at this time. Winds will remain light through
the period.

Britt

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

WFO LSX

Area Forecast Discussion

National Weather Service Marquette MI

744 PM EDT Tue Mar 10 2020

.SHORT TERM...(This evening through Wednesday)
Issued at 416 PM EDT TUE MAR 10 2020

WV imagery and RAP analysis indicated a nearly zonal pattern through
the northern CONUS with an upstream shortwave trough into the
western Dakotas. At the surface, ridging prevailed through the
western Great lakes with light winds and plenty of sunshine. Mid
clouds were increasing from MN into western WI with WAA/isentropic
lift ahead of a trough through the Western Plains.

Tonight, expect clouds will continue to move in and thicken ahead of
the approaching shortwave. Some light snow will also develop
overnight as 285k-290k isentropic lift with weak to moderate 700-300
qvector conv associated with the shrtwv moves through. However,
given the moderate dynamics and moisture inflow and the strongest
forcing to the south of Upper Michigan, accumulations will be light,
generally around an inch or less, greatest over the south and
east.

Wednesday, mid level and sfc ridging are expected to take over with
any remaining snow over the east ending early. Enough dry air
will also move in with partial clearing allowing temps to rebound
into the upper 30s to lower 40s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 346 PM EDT TUE MAR 10 2020

The long-term period starts out with punctuated precip chances
through week`s end, with Thursday being the day most likely to see
precip. Initially, southerly flow at the surface and warm air to
the west will allow for WAA to be ongoing through the overnight
period tomorrow into Thursday morning. Under this regime, a
generally non-diurnal temp curve looks to occur tomorrow night,
with the coolest temps of the night occurring early in the west,
with a general warming trend from west to east as the night
progresses. However, with widespread cloud cover overhead, the
temp differences won`t be extreme, moderating temps throughout
the night.

For Thursday, which looks to be the most impactful day of the
long-term period, there are some fairly significant differences
amongst the models with respect to how quickly the colder air
advects in behind a cold front associated with a deepening low
over northern Ontario. Therefore, have trended toward more of a
blend of precip types, predominantly a rain/snow mix, as the
colder airmass attempts to work its way in. With that warmer air
potentially taking a bit of time to completely dissipate from the
surface, and given that we`re inching ever so closer to spring
with a more favorable sun angle, have snow (mixing with rain)
mention for Thursday but little to no accumulation expected. As
this timeframe gets closer and models *hopefully* come into better
agreement on the timing of colder air arriving, better refinement
in these finer details should be more easily achieved.

By Thursday night, the precip should be transitioning completely
over to snow, especially by early Friday. As mentioned, precip
chances will linger through the end of the traditional work week,
with a ridge moving in over the weekend to clear things out. The
next precip chances look to move in early next week as a shortwave
looks to move through. Temperatures on Thursday may rise well
into the 40s before falling throughout the day from west to east,
with closer to normal temps anticipated for Friday into Saturday.
The warming trend looks to ramp back up later in the weekend, with
a general trend to rise back above normal for mid-March.
&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 743 PM EDT TUE MAR 10 2020

An approaching disturbance should bring MVFR cigs and some -sn to
KSAW overnight. There is a small potential that cigs could fall to
IFR. The -sn will exit Wed morning, followed by MVFR cigs scattering
out by early aftn. The -sn will likely pass s of KIWD/KCMX, and VFR
conditions should prevail thru the fcst period at both terminals.
That said, there is a low potential that MVFR cigs could appear for
a time late tonight/Wed morning.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 416 PM EDT TUE MAR 10 2020

Light winds will prevail, generally less than 20 knots through
Wednesday. Attention then turns to a surface trough progged to track
across the Great Lakes, the exact track remains uncertain at this
time. Ahead of the trough, south winds should increase to 20-25
knots Wednesday night/Thursday. Behind this low, west to northwest
gales should overspread the lake as the low deepens over
Ontario/Quebec on Friday. Could be northwest gales up to 45 knots on
Friday as this low strengthens over Quebec. This would be the
strongest winds expected during the forecast.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

SHORT TERM...JLB
LONG TERM...lg
AVIATION...Rolfson
MARINE...JLB

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 342 PM CDT Tue Mar 10 2020

The center of a surface ridge is located over Missouri this
afternoon, and low pressure has been strengthening in southeastern
Colorado. Water vapor imagery this afternoon shows a trough from
North Dakota into Wyoming and a large cutoff low spinning well off
the coast of California. A layer of stratus clouds held tight in our
sky today, which limited warming into the afternoon. Surface
dewpoints slowly increased through the day in central and eastern
Kansas ahead of the surface low. That system will work its way
across Oklahoma tonight while the upper trough noted on water vapor
works toward the western Great Lakes region. Ascent ahead of the
wave will combine with increasing moisture to produce rain/storms
tonight. The better dynamics for thunderstorms looks to remain just
south of the CWA where RAP soundings show a couple hundred Joules of
elevated CAPE developing by 06Z. Closer to home, light rain is
possible tonight, mainly south of Interstate 70. This system will
quickly scoot east, so rain should clear by early in the morning.
Patchy fog/low stratus is looking possible again early tomorrow,
especially if clouds can clear a bit behind the departing system.
If fog/stratus does develop, temperatures will be a little slower
to warm than currently forecast. However, sunshine is expected
tomorrow afternoon with temperatures expected to warm nicely into
the 60s...again dependent on morning cloud cover.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 342 PM CDT Tue Mar 10 2020

On and off chances for precipitation accompany our long-range
forecast period.

Dry weather midweek will be brief as POPs increase ahead of an
approaching cold front on Thursday morning. Low level moisture
will increase ahead of the front but overall ascent looks fairly
limited. Thus, light rain is expected with QPF around a tenth of
an inch. Thursday`s system also looks to move through the area
fairly quickly so rain chances are limited to mainly the morning
hours. Gusty northwest winds will develop behind the front
Thursday afternoon, ushering in a cooler and drier airmass from
the northern Rockies. High pressure will take control on Friday,
allowing for a dry but somewhat cool day.

The large upper closed low over the Pacific will finally advect
northeastward over the southwestern CONUS late this week and become
a weaker open wave. Large scale ascent ahead of the wave is noted in
models which also show a large area of precipitation developing over
the region. As such, POPs increase quickly Friday night into
Saturday. With some cooler air still in place, light snow is looking
possible early Saturday, transitioning back to rain during the
afternoon. An active pattern looks to continue into early next week
with more opportunities for rain/snow.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 638 PM CDT Tue Mar 10 2020

VFR conditions are expected to continue through 10Z with some mvfr
cigs and vsbys possible, especially at MHK. Amount of clearing
will be key with system moving through and clearing behind it.
Expect some vcsh at MHK after 06Z til about 10Z. Confidence was to
low to include vcsh at TOP and FOE at this time. If skies clear
than some mvfr to ifr vsbys may be possible from 11Z-14Z. VFR
expected with light winds after 15Z.

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Teefey
LONG TERM...Teefey
AVIATION...53

Area Forecast Discussion

National Weather Service Las Vegas NV

750 PM PDT Tue Mar 10 2020

.SYNOPSIS...A Flash Flood remain in effect effect for parts of San
Bernardino and all of Inyo County with particular concern across the
southern Owens Valley, Death Valley, and perhaps the Taboose Burn
Scar this evening as the heaviest rain is expected. A brief lull is
expected Wednesday afternoon and night before another round of heavy
rainfall returns to the forecast Thursday into Friday. This second
area of heavy rain looks to be focused across eastern San Bernardino
and southern Mohave Counties. This active pattern is expected to
continue even into next week as yet another low pressure system
looks to impact the region.

.UPDATE...Scattered light to moderate rain has redeveloped over much
of southern Inyo, San Bernardino, Clark and Mohave Counties this
evening with most of widespread moderate to heavy rain east of the
area affecting portions of Arizona. However, showers are starting to
enhance over southern Inyo which are expected to increase and move
north across the county. This could have impacts on mainly the
Georges and Taboose Fire burn scars with the potential of debris
flows and rock slides. The current FF watch for those areas remains
in place and will not make any changes. There could be some isolated
thunderstorms overnight, but latest guidance actually shows less
instability than previous runs. However, thunderstorm chances are
expected to increase Wednesday late morning and afternoon with some
isolated areas of heavy rain. No updates at this time, but rainfall
amounts may be less than expected overnight.

PREV DISCUSSION
225 PM PDT Tue Mar 10 2020

.DISCUSSION...Through and Wednesday night.

The widespread area of light to moderate rain that moved in
overnight did dissipate as it moved north of Las Vegas as hi-res
models suggested. Light rain showers have been isolated more than
scattered so far this afternoon under cloudy skies. There have been
some breaks in the overcast southwest of Las Vegas, not so sure
we will reach the low 60s this afternoon.

Visible imagery starting to show scattered thunderstorms developing
east of the upper low from central California southeast to San
Diego. Model output remains consistent that showers and
thunderstorms associated dynamics within northeast quadrant of upper
low and decreasing instability will expand in coverage across
northwest San Bernardino and Inyo Counties this evening. This area
will shift eastward into Clark County/eastern San Bernardino County
late this evening and overnight. No change made to the Flash Flood
Watch as expecting higher rain rates within Inyo County, more
specifically Death Valley NP. Those higher rain rates may pose a
threat and bring minor flooding to southern Nye, Clark and eastern
San Bernardino Counties early Wednesday morning. Any impacts from
snowfall will be above 8500 feet with 3-5 inches possible in upper
Lee Canyon and Whitney Portal. 1-3 inches possible in upper Bishop
Creek. Similar to today, showers and thunderstorms will become more
isolated Wednesday afternoon and night.

Thursday-Friday...The upper low is progged to finally move into
southern California and eject east into Arizona Friday. This will be
another period of active weather, specifically for San Bernardino,
Mohave and Clark Counties. Dynamics become very impressive within
the lower Colorado River Valley Thursday afternoon with that energy
pivoting northward into our area Thursday night. On our latest
coordination call with WPC there was no change made to the current
Excessive Rain Outlook. Based on GFS and EC ensemble QPF output,
specifically for Needles, Lake Havasu and Kingman confidence has
been increasing in this second round of heavy rain. A Flash Flood
Watch will probably be needed for southern Mohave County and eastern
San Bernardino County, including Morongo Basin late Thursday
afternoon into Friday.

Saturday and Beyond...As this low finally gets out of the southwest
Saturday models continue to advertise the next colder low slowly
approaching from the northwest. Positioning of the trough over the
weekend will lead to increasing southwest winds with some light
showers still lingering over parts of the area. Precipitation
chances increase the first half of next week as the trough moves
overhead. Again, the system is colder so will be expecting some
snowfall at lower elevations.

.HYDROLOGY...regarding the Taboose Burn Scar.
A Flash Flood Watch remains in effect through late tonight. Latest
guidance continues to show the burn area getting at a minimum light
rain, and at a maximum briefly heavy rain this evening. The HRRR
debris flow tool shows up to a half inch rainfall rates at this
time, but only briefly between 7 pm and 10 pm this evening. This
wouldn`t quite be enough for significant debris flows most likely,
but could result in some minor issues on the creeks. However,
continued close attention will continue this evening as these rain
rates could overachieve and result in more significant impacts.

.AVIATION...For McCarran...Moderate confidence in forecast details
this afternoon through Wednesday morning as a weather system brings
several rounds of rain with low CIGs and possibly reduced VSBYs to
the area.

Light rain occasionally at or near the airport will remain through
the remainder of the afternoon with CIGS around 3-3.5k feet, but
occasionally dropping to around 2k feet at times. It`s possible that
CIGS could raise to around 4-5k feet late this afternoon, but
confidence is low in that occurring.

Rain is likely tonight. Showers should become more numerous after
00Z and eventually become an area of rain pushing in from the south.
Low confidence in current timing of more impactful rain, though
chances increase quickly after 06Z. Between 06Z-12Z, rain may be
heavy enough to reduce visibility and low status to 1000ft. Moderate
confidence that ceilings drop to 3000-5000ft and remain there
through Wednesday morning.

After 12Z, rain may lighten/become more scattered in nature.
Continued with this trend, however it is possible that the heavy to
moderate rain and low ceilings will continue through 15Z or 18Z
Wednesday.

For the rest of southern Nevada, northwest Arizona and southeast
California...A weather system will continue to push into southern
California northeastward into southern Nevada through tonight,
bringing with it widespread aviation impacts. Rain showers near DAG
will continue at times through the day until more substantial rain
moves in after 00Z. This rain shield will continue to push north and
west, with it bringing at least MVFR CIGs, with potentially IFR
ceilings and reduced visibility at times. Slight chance of
precipitation ahead of the bigger push this afternoon, however it
should be lighter precipitation and isolated to scattered in nature.
Rain tonight may be heavy at times across all the TAF sites. Low
confidence in the details of the forecast, including rain timing and
when/how low ceilings will lower.

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

UPDATE...Gorelow
DISCUSSION...Pierce
AVIATION...Gorelow

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