Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/13/23
Area Forecast Discussion
National Weather Service Cheyenne WY
522 PM MDT Wed Apr 12 2023
.SHORT TERM...(This evening through Friday)
Issued at 225 PM MDT Wed Apr 12 2023
Well above average temperatures continue to impact the region this
afternoon as observations range from the 70s and 80s east of the
Laramie Range, and 50s to 60s west of the Laramie Range. Several
areas have already broken the daily record high, including SNY, BFF,
AIA, and CYS. Gusty southwest winds are bringing in much appreciated
warmth to the area ahead of a slow-approaching frontal boundary on
our northern forecast borders. However, this has resulted in
elevated fire weather concerns for the I-25 corridor into the NE
Panhandle. We will continue to monitor satellite imagery due to the
well above average temperatures and dry conditions combining with the
breezy winds in the event new fire activity appears. Light rain
showers are appearing on radar as weak echoes are being captured due
to some cumulus clouds east of the Laramie Range.
The rest of the afternoon into the evening hours will bring light
rain showers, and even the potential for a rumble of thunder along
the stalled cold front boundary of the northern NE Panhandle. The
NamNest and HRRR are highlighting a region of Niobrara, Sioux, and
Dawes county where weak rain showers could result in localized
strong wind downdrafts. Modeled soundings show inverted-V features,
and DCAPE values of 750-1300 J/kg that are present between 21Z-3Z
today. Should this occur, brief wind gusts of 40-50+ MPH may occur
in the aforementioned areas. Overnight temperatures should remain
mild, with lows in the 40s and 50s east of the Laramie Range, and
the 30s/40s west of the Laramie Range. This could assist with
increased snowmelt occurring in the higher terrain. We will monitor
the AHPS hydrographs to see if river levels creep up to near any
action stage criteria by early tomorrow morning. Hi-res guidance
does depict some light rain shower activity being possible by early
Thursday morning along the Laramie Range and the foothills, but it
is unlikely to be much more than a few sprinkles.
Thursday and Friday will be active with respect to a large weather
shift from above average temperatures back to near or below normal
readings. We will have above average temperatures ahead of a slow
advancing cold front from the west and north. Strong WAA will occur
ahead of this frontal passage, leading to several areas seeing
daytime highs in the 70s to low 80s from a corridor of I-25/HWY-26
to the east and southeast. Other regions will see cooler
temperatures due to cloud cover and precipitation occurring. With
the warmer temperatures and southwesterly flow being present, it
will increase the chances for fire weather concerns. Low RH values
and breezy winds have prompted a Fire Weather Watch for FWZs 435-437
in the NE Panhandle from 18Z-0Z Thursday afternoon. Forecast zones
further to the west and north are likely to see an earlier daytime
high temperature before temperatures cool the remainder of the day.
With the cloud cover being present from west to east, some locations
across Carbon and Albany County may struggle to reach the forecast
high. One additional concern to mention is that there will be very
strong surface pressure gradients present on Thursday because of the
cold FROPA. The gradients really begin to tighten by Thursday
afternoon across the cwa, especially our western forecast zones. The
winds aloft are not all that strong, but there will be strong
subsidence coupled with the tightened shallow pressure gradients
near the surface. There is not a mountain wave signature modeled at
this time, but the wind prone and gap areas of southeast WY near
Arlington and Elk Mountain could easily gust near or above 55MPH
Thursday. The next forecast package may include a short-fused High
Wind headline despite the wind direction not being favorable as a
southwesterly component.
Thursday evening includes the chance for rain showers and general
thunder to be present, especially the southern tier of the NE
Panhandle. SPC day 2 outlook does include a sliver of Marginal
Severe Wx being possible for the BFF/IBM/SNY/AIA areas. MUCAPE
values look meager, at or below 500 J/KG. But there are steep lapse
rates, moisture, and forcing thanks to the frontal boundary being
present. Isolated rain showers east of I-25 into the NE Panhandle
will be present Thursday night, with a rain/snow mix and snow
showers west of I-25 slowly advancing to the east by daybreak
Friday. With the increased sun angle, and 700mb temperatures
struggling to stay below -5C to -10C on Friday, there is the
potential for the rain/snow line to retrograde to the north and
west. At this time of inspection, snowfall accumulations will likely
be confined to the higher terrain of the Laramie Range, and
Snowy/Sierra Madre Ranges. Winter headlines do not appear likely at
this time regarding Thursday night and Friday. Daytime highs on
Friday will be much colder due to CAA and cloud cover being present.
Would expect a large swath of 30s to upper 40s for a majority of the
cwa, with potentially 50 degrees being achieved in the North Platte
River Valley. Any lingering precipitation should begin to wind down
by late afternoon into early Friday evening.
.LONG TERM...(Friday night through next Wednesday)
Issued at 235 PM MDT Wed Apr 12 2023
Medium to long range models in good agreement this weekend and
early next week, but solution then diverge significantly for the
middle portion of next week. For Saturday, Pacific upper level
trough will be exiting the area to the east and northeast Friday
night and early Saturday. Models show that most of the dynamic
forcing will be well east of the Wyoming/Nebraska border by late
Friday evening with a secondary disturbance aloft, behind the
primary trough axis, digging southeast across southern Wyoming.
There should be enough convergence and topographic lift to
initiate widely scattered or scattered snow showers across Carbon,
Albany, and the western portions of Converse, Platte, Laramie
Counties along Interstate 25 into early Saturday afternoon. Models
indicate quite a bit of dry air behind the main trough, so do not
expect a significant coverage of precipitation outside of the
mountains. Increased POP between 20 to 40 percent, with lower
probs east of I-25 through Saturday afternoon. Any snow
accumulations should be mainly confined to the southeast Wyoming
mountains during this time period. Expect windy to very windy
(gusts of 45+ mph) conditons across some of the wind prone areas
too as low level pressure gradients increase through Saturday
night. Do not expect High Wind Warning criteria at this time.
All models then show a broad upper level ridge axis translating
eastward into the Rocky Mountain Region and amplifying as it
tracks eastward. Sunday through most of Tuesday should be much
warmer than normal with daytime highs returning to the 60s and 70s
outside of Carbon County. Lingering surface snowpack across Carbon
County may result in temps in the 40s and 50s, but did not go
quite that low yet since some of this snowpack will likely melt
leading up to Monday. For now, did lower temperatures a few
degrees for Saratoga, Rawlins, and Dixon. Otherwise, dry weather
is expected through Monday night with increasing cloud cover ahead
of the next system.
Low confidence forecast once we get into the middle portion of
next week (late Tuesday and Wednesday). Models and ensemble are
struggling with the timing of the next Pacific trough approaching
the region from the Pac NW coastline. The ECMWF and the Canadian
shows the trough moving across the area bringing rain/snow and
much colder temperatures to southeast Wyoming by Monday night. The
GFS on the other hand keeps the ridge axis over our eastern zones
across the high plains with dry weather. Most ensemble members
(~75%) agree with the GFS and delay the arrival of the cold front
until later in the week. With this in mind, blended POP forecast
with the CONSALL and nudged POP forecast on the lower end of the
slight chance scale due to lower than average confidence until
late Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 521 PM MDT Wed Apr 12 2023
Isolated showers will continue in far northwest Nebraska this
afternoon. CDR and perhaps AIA may see brief instances of light
rain as weak convection moves through. Any lingering showers will
quickly diminish after sunset. Gusty southwest winds will also
diminish at sunset area-wide. Expect VFR conditions through the
forecast period.
&&
.FIRE WEATHER...
Issued at 151 PM MDT Wed Apr 12 2023
Elevated to near critical fire weather conditions will remain
present this afternoon and again for Thursday afternoon. Overnight
humidity values will recover to 45-65 percent by morning for FWZs
east of the Laramie Range. Minimum humidity values between 10-15
percent will combine with breezy southwest winds of 15-25MPH on
Thursday. Red Flag conditions are possible in the Nebraska
Panhandle from 1200-1800 for FWZs 435-437.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...Fire Weather Watch Thursday afternoon for NEZ435>437.
&&
$$
SHORT TERM...BW
LONG TERM...TJT
AVIATION...MAC
FIRE WEATHER...BW
Area Forecast Discussion
National Weather Service Grand Forks ND
1021 PM CDT Wed Apr 12 2023
.UPDATE...
Issued at 1019 PM CDT Wed Apr 12 2023
Updated to remove pops 06z to 09z in far NW cwa (Cando ND). Kept
in 09z-12z and highly doubt anything then as flow supports keeping
main mid level moisture west and northwest of our area. Tweeked
temps a bit on Thursday a bit warmer as HRRR is trending warmer,
though HRRR sfc temps may be a bit much with mid 70s Wadena and 60
in GF.
UPDATE Issued at 659 PM CDT Wed Apr 12 2023
Updated sky cover to be a bit more cloudy in NW fcst area due to
high clouds and then Wednesday daytime a bit more cloudy due to
extensive high clouds and some mid clouds. Late tonight into Thu
AM some hint at elevated shower chance in SE ND into MN 12z-15z
Thu period. We have that covered in slight chc pops and that seems
reasonable.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 231 PM CDT Wed Apr 12 2023
Currently, upper ridge axis is east of our area with southwesterly
flow aloft setting up for the next couple of days, with a surface
trough slowly pushing southeast out of the southern RRV and WC MN
tonight. This surface trough is expected to stall to our south and
southeast tonight into Thursday as southwesterly flow aloft and
subtle upper height falls promotes poleward flow in the low
levels. This poleward transport of low level moisture is beginning
to be noticed via ALPW products within the southern and central
Plains, even in spite of the cutoff low in the Southeast CONUS.
Guidance like NAM3k and FV3 WRF showed some potential for
elevated thunderstorms as early as late tonight into early
morning Thursday sparked by LLJ/low level WAA overrunning the
stalled boundary, however current placement of sufficient moisture
content rooted near the LLJ does not appear to be enough to
generate convection. Thus we did not include this into the
forecast. There still could be some mid/upper level driven showers
closer to the international border and/or northeast ND area as
early as tonight.
Some light showers will be possible during the day tomorrow as
upper/mid residual moisture pushes over the area from the exit
region of upper troughing over the Intermountain West, but is
expected to be very light.
Getting into Thursday night, most guidance indicates a mid level
wave and LLJ development in the vicinity of the stalled boundary
lee of this wave to spark scattered showers and thunderstorms out
of SD into ND and NW MN. Some of this convection could produce
heavy rain rates between 0.5-0.75 inch per hour, and some small,
non-impactful hail can`t be ruled out given low freezing heights
and marginal but present effective shear. Should there be training
of convection, this could have local impacts to flooding
potential should rain help rapidly melt lingering snowpack and/or
fall on top of frozen/saturated ground.
.LONG TERM...(Friday through Wednesday)
Issued at 231 PM CDT Wed Apr 12 2023
Friday through Saturday, upper trough is expected to move east
across our region. Initially on Friday into Saturday, shortwave
energy will promote scattered to numerous rain showers, with
embedded thunder possible. Similar to Thursday night, there is
some potential for training of heavier rain rates Friday night
into Saturday morning, this time favored in our southern and
eastern areas. As the mid level wave moves through the area, there
still remains some possibility for rain transitioning to snow
Friday night through Sunday. Light snow amounts up to 4 inches
remain possible, but impacts are mitigated due to warm surface
temperatures especially during the day.
Behind the departing trough Saturday, drier and relatively cooler
conditions are favored as upper ridging starts to build into the
Northern Plains into early next week. Confidence in the synoptic
pattern degrades mid to late next week, with ensembles painting
either a blocking pattern and upper ridging/dry conditions with
milder temperatures back into the region, or progressive pattern
with the upper ridging breaking east and more upper troughing
nosing into the Plains which would bring more chance for
precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 659 PM CDT Wed Apr 12 2023
VFR anticipated into Thursday morning with high clouds and a
northwest wind 5 to 12 kts. Some chances for MVFR cigs to develop
Thursday aftn as moisture increases.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...CJ
LONG TERM...CJ
AVIATION...Riddle
Area Forecast Discussion
National Weather Service Mobile AL
1008 PM CDT Wed Apr 12 2023
...New UPDATE...
.UPDATE...
Issued at 1008 PM CDT Wed Apr 12 2023
Minor adjustments were made to expand the higher winds northward
over the marine area and to expand the Gale Warning into the
nearshore waters. The remainder of the forecast remains on track.
/13
&&
.PREV DISCUSSION... /issued 713 PM CDT Wed Apr 12 2023/
..New AVIATION...
AVIATION...
(00Z TAFS)
Issued at 713 PM CDT Wed Apr 12 2023
Showers and thunderstorms over the Gulf will spread inland
tonight, with coverage tapering off over the coastal counties
late Thursday morning. VFR conditions gradually lower to MVFR
near the coast later this evening and then over the remainder of
the area tonight. IFR ceilings will also be possible across the
area early Thursday morning. Conditions are then expected to
improve to MVFR by late morning. East to northeast winds 5 to 10
knots increase to 10 to 15 knots tonight, potentially 15-20 knots
near the coast, then become southeasterly Thursday morning and
southwesterly Thursday afternoon as a surface low moves across the
area. /14
PREV DISCUSSION... /issued 354 PM CDT Wed Apr 12 2023/
.New NEAR TERM, SHORT TERM, LONG TERM, MARINE...
NEAR TERM...
(Now through Thursday)
Issued at 354 PM CDT Wed Apr 12 2023
An upper low centered over southwest Louisiana (and part of a Rex
Block pattern) drifts slowly to near the border of central
Mississippi/central Alabama through Thursday. An associated
surface low appears to be located about 190 miles south of the
mouth of the Mississippi River per the current satellite loop. The
HRRR and 12Z GFS seem to have initiated fairly well with this
feature, and deepen the surface low while taking it to coastal
Mississippi by 12Z Thursday. The HRRR/GFS continue the surface low
slowly northward into central Mississippi on Thursday, with some
uncertainty as to how quickly the system weakens. Other guidance
is in general agreement with this motion. A frontal boundary
extending eastward from the surface low is expected to lift
northward into the immediate coastal areas by 12Z Thursday, then
continue northward through much of the remainder of the forecast
area through the day. Current radar shows an area of rain across
much of the marine area which is spreading into the southern
portion of the area. A major uncertainty for the rest of the
forecast period is how quickly a dry slot currently wrapping
around the upper low impacts coverage of precipitation. After
likely to categorical pops early this evening, have had to limit
the higher pop values to balance the possible outcomes. Coverage
is expected to decrease sufficiently over the southern portion of
the area to go with chance pops Thursday morning, then pops
decrease for much of the area through the afternoon. Shear values
increase tonight with the 850 mb jet reaching 30-40 knots, then
the 850 jet diminishes to near 20 knots Thursday morning.
Instability values will be very low until early Thursday morning
when SBCAPE values of 500-1000 J/kg will be realized near the
coast. Similar SBCAPE values then develop over the eastern and
central portions of the area on Thursday. While there does look to
be an intersection of favorable shear and instability generally
over the coastal counties late tonight into about mid Thursday
morning, the potential for any strong storms, much less severe
storm potential, is very murky (that would be underlined if
possible) given the uncertainty with how quickly the dry slot will
impact convection. Lows tonight range from the mid to upper 50s
along and west of I-65 to the upper 50s/lower 60s east of I-65.
Highs on Thursday will be in the 70s. A high risk of rip currents
continues through the period. A high surf advisory remains in
effect for beach areas until 1 pm Thursday. /29
SHORT TERM...
(Thursday night through Sunday)
Issued at 354 PM CDT Wed Apr 12 2023
An upper low will be located roughly over the border of central
Mississippi/central Alabama early Thursday evening then slowly
lifts northward and eventually breaks down to an open wave over
the interior eastern states on Friday. A nearly co-located
surface low weakens while following the system well off to the
north, with progressively drier air flowing into the area in the
wake of the system. Will have slight chance to chance pops for
most of the area Thursday evening tapering off to dry conditions
for Friday. A large upper trof meanwhile advances across the
western states into the central states through Saturday and begins
to strengthen Saturday night. An associated surface low lifts
from the central Plains to the Great Lakes, and in the process
brings a cold front through the forecast area late Saturday night
into early Sunday morning. Deep layer moisture improves over the
area as the front approaches, and will have slight chance to
chance pops return to the forecast for Saturday. Have continued
with chance pops for Saturday night, then slight chance to chance
pops follow for Sunday morning as the front moves through the
area. For Sunday afternoon, have gone with small pops over the
eastern portion of the area for lingering precipitation in the
wake of the front. Shear values look to be generally modest ahead
of the frontal passage, and instability values appear to be
generally limited except for possibly the western portion of the
area Saturday afternoon into the early evening hours. At this
time, the environment does not appear to support much of a risk
for strong to severe storms but will continue to monitor. A high
risk of rip currents Thursday night will be followed by a moderate
risk for Friday and Friday night, afterwards a low risk is
anticipated. Lows Thursday night range from the mid to upper 50s
around and west of I-65 to around 60 further to the east. Lows
Friday night range from the mid 50s well inland to the mid 60s at
the immediate coast, then Saturday night will have lows in the
lower to mid 60s. Highs on Friday and Sunday will be mostly in the
mid to upper 70s, and highs on Saturday mostly range from the
upper 70s to lower 80s. /29
LONG TERM...
(Sunday night through Wednesday)
Issued at 354 PM CDT Wed Apr 12 2023
Very dry deep layer air flows into the area in the wake of the
cold front along with a surface high building into the area
through Monday night. A surface ridge evolves along the northern
Gulf coast by Tuesday which allows for a light return flow to
ensue, but deep layer moisture looks to remain too limited to
support consideration of pops and have continued with a dry
forecast through Wednesday. /29
MARINE...
Issued at 354 PM CDT Wed Apr 12 2023
A Gale Warning is in effect for the 20-60 nm portion of the marine
area until 10 pm this evening for east winds 25 to 30 knots with
frequent gusts to gale force. A Small Craft Advisory will
otherwise be in effect until Thursday afternoon to allow enough
time for winds and seas to subside. Will need to closely monitor
trends this evening for possible expansion of the Gale Warning.
/29
&&
.PRELIMINARY POINT TEMPS/POPS...
Mobile 59 73 58 78 61 79 64 79 / 90 50 20 0 0 40 50 30
Pensacola 62 74 63 75 64 78 67 79 / 70 50 30 0 0 30 50 40
Destin 64 76 65 76 66 77 69 79 / 60 60 30 0 0 30 50 40
Evergreen 57 77 58 77 57 82 62 78 / 70 60 30 0 0 20 40 30
Waynesboro 55 70 55 78 58 81 61 75 / 70 70 20 0 0 30 40 20
Camden 55 76 57 76 57 83 62 76 / 70 70 40 10 0 20 40 20
Crestview 59 78 59 80 57 83 64 81 / 70 60 30 0 0 20 40 40
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk through late Thursday night for ALZ265-266.
High Surf Advisory until 1 PM CDT Thursday for ALZ265-266.
FL...High Rip Current Risk through late Thursday night for FLZ202-204-
206.
High Surf Advisory until 1 PM CDT Thursday for FLZ202-204-206.
MS...None.
GM...Small Craft Advisory until 9 AM CDT Thursday for GMZ630>636.
Gale Warning until 5 AM CDT Thursday for GMZ650-655-670-675.
Small Craft Advisory from 5 AM to 1 PM CDT Thursday for GMZ650-
655-670-675.
&&
$$
This product is also available on the web at:
www.weather.gov/mob
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1044 PM CDT Wed Apr 12 2023
.UPDATE...
Issued at 821 PM CDT Wed Apr 12 2023
Highs today reached at least the upper 80s across southern MN into
parts of west central WI, with several locations touching 90. A cold
front is sagging southeast across western and parts of central MN
this evening, but will stall overnight and then lift back north
Thursday. The thermal ridge responsible for today`s hot temperatures
will settle a little farther north Thursday. A pocket of drier air
will advect north and ground conditions will be drier after today`s
heat. Therefore, areas a little farther north could have their shot
at 90 Thursday, including the Twin Cities. If this were to occur, it
would be the earliest 90 on record by a couple days.
&&
.DISCUSSION...(This evening through Wednesday)
Issued at 303 PM CDT Wed Apr 12 2023
KEY MESSAGES:
- Critical fire weather conditions expected Thursday.
- Speed of next system continues to slow down, with highs close to
80 still possible Friday over eastern MN and western WI before
precipitation chances and cooler temperatures move in Friday night.
- Best rain chances come Friday night into Saturday, with some mix
with snow still possible Saturday night for any lingering
precipitation.
- Cooler but mostly dry through the middle of next week.
It`s a beautiful summer day out there today as temperatures have
been tracking well with our forecast, with record highs still
expected to be toppled at MSP and EAU. We`ve seen a weak
front/pressure trough slowly sag southeast into western through
northeast MN this afternoon, but this boundary will stall out from
roughly Redwood Falls to Duluth tonight. Along this boundary, winds
will be light, with the potential for fog existing. However, this
airmass is so dry, we are not anticipating widespread fog, even
where we continue to see some lingering snow melt.
Tonight, we`ll see the LLJ strengthen from eastern Neb into southern
MN. The result of this LLJ is that it will push the boundary
settling over our area tonight back north as a warm front for
Thursday. As a result, forecast potential highs for Thursday took a
step up today, with record highs again possible for MSP/EAU. The
bigger issue here resides with the fire weather threat for Thursday.
The HRRR in particular is very aggressive with mixing out dewpoints
as the boundary lifts north and our moisture depth becomes
shallower, with dewpoints mixing down to around 30 from south
central and southeast up into east central MN and western WI.
Resultant RH values on the HRRR are down around 15%. We didn`t go
completely down that road, but did lower humidities for Thursday,
with minimum RH values down around 20% thanks to the presence of
temperatures again into the low to mid 80s. With that LLJ up into
southern MN, winds are also looking stronger on Thursday as well,
with gusts of 30 to 40 mph expected over south central MN up toward
the Twin Cities. Given these low RHs and stronger winds, we issued a
Fire Weather Watch for Thursday from Brown up to Anoka county, then
over to Chippewa county in WI.
For Thursday night, it will be another mild night, though
precipitation is expected to continue along the periphery of the
thermal ridge to the west and north of our area, with dry conditions
expected in the MPX area through 12z Friday.
The longer term period begins with a low pressure system entering
the region from west to east, swinging a broad cold front across the
area with showers beginning before sunrise on Friday in western
Minnesota. This system and front will swing through the area slowly,
with precipitation likely continuing in waves through early Sunday
morning until the system ejects towards eastern Ontario later on
Sunday. Broad synoptic scale forcing along the front will keep light
to moderate rainfall across the area during a good portion of the
event. The main question on everyones mind based on how ensemble and
deterministic guidance has trended over the past couple of days, is
how much snow do we end up seeing? The 12z deterministic runs of the
GFS/ECMWF slowed the system down, keeping it around for about 8-12
hours longer and giving us a better shot at seeing snow during the
last 1/3rd as cold air continues to wrap around behind the front. WPC
& NBM continue to keep things as mostly rain with minimal snow,
however a few GEFS/EPS members show up to 2-4 inches of snow across
portions of eastern Minnesota to western Wisconsin, and based on the
speed of the system this could even bump up a bit more. Bottom line
is that we could see a slippery mess of snow late Saturday into
Sunday especially, which should melt off fairly quickly given the mid
April sun angle and temperatures returning to the 50s.
Ridging returns behind the departing system to begin the week, with
cooler temperatures especially compared to today and tomorrow as
highs struggle to get out of the 50s. Wednesday we could see another
smaller rain chance, however for now the forcing appears fairly weak
and we are cut off from a significant amount of moisture to produce
stronger or more widespread showers. The main story beyond Sunday
will be in near to slightly below normal temperatures with our
normals in the mid 50s by that point in April.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1044 PM CDT Wed Apr 12 2023
VFR through the period. A front has reached central and western MN,
shifting winds northwest. The front will stall by 02Z, then lift back
north Thursday with south winds returning area wide.
KMSP...No additional concerns.
/OUTLOOK FOR KMSP/
FRI...VFR. Chance -RA/MVFR late. Wind S 15-20G30 kts.
SAT...MVFR. -RA likely, Wind NW 10-15 kts.
SUN...MVFR. Chc -RASN. Wind NW 15-20G30 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Fire Weather Watch from Thursday afternoon through Thursday evening
for Anoka-Blue Earth-Brown-Carver-Dakota-Faribault-Freeborn-
Goodhue-Hennepin-Le Sueur-Martin-Nicollet-Ramsey-Rice-Scott-
Sibley-Steele-Waseca-Washington-Watonwan.
WI...None.
&&
$$
UPDATE...Borghoff
DISCUSSION...MPG
AVIATION...Borghoff
Area Forecast Discussion
National Weather Service Seattle WA
836 PM PDT Wed Apr 12 2023
.SYNOPSIS...Generally dry conditions tonight into early
Thursday before a weak front brings a chance for some showers over
Western Washington. Drier conditions return Friday as a weak upper
ridge builds into the region. A broad trough over the northeast
Pacific will bring a return of active weather early next week.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...A few showers have
developed over Pierce county this evening but activity should be
fading away over the next hour or two (per HRRR guidance).
Otherwise, dry conditions elsewhere. Another chilly night on tap
with overnight lows in the 30s. 33
Previous discussion...Current radar showing some light
echoes...mostly along a NE to SW line along the east side of the
Olympics, through Mason County and into the SE corner of Grays
Harbor County. Another batch of intermittent echoes can be found
over the northern two-thirds of the Cascade foothills. Nothing
spectacular expected from either of these areas...mainly sprinkles
or light showers at best. Remainder of the area is generally dry
at the time of this writing with current satellite imagery showing
increasing areas of clearing as clouds move southward along with
the upper level low, now along the OR coast.
While that clearing trend will extend into the evening by late
tonight and the overnight period/early morning, will start to see
clouds filter in as incoming weak frontal system approaches the
coast. While the western half of the CWA may see some morning
precip, the best chances for showers is expected to be during the
late morning and afternoon before PoPs diminish during the
evening. Most locations east of the Sound will only see PoPs in
the 10-30 pct range /slight chance to low-end chance/ while the
Olympic Peninsula and higher elevations of the Cascades will see
higher chances /around 60 to 70 pct/. Both ensembles and
deterministic models see this front weakening as it moves over the
area and even though some locations may get rain, precip amounts
will be relatively small...not getting above one- tenth of an inch
in many locations.
The front fizzles out Thursday night allowing for a weak upper level
ridge to nudge into the area. This will help to keep the area dry
throughout Friday. In fact, locations east of the Sound may see that
dryness extend into at least Saturday afternoon as the next frontal
system seems to get hung up along the coast before pushing in late
Saturday afternoon/Saturday evening.
Temps over the short term will see highs Thursday similar to those
of today, generally in the upper 40s to lower 50s while the upper
level ridge will give afternoon temps a shot in the arm with lower
to mid 50s expected. These still fall short of normals however, as
highs this time of year are typically in the upper 50s. Overnight
lows tonight and Thursday night will generally range from the mid
30s to around 40 while lows Friday warm slightly, getting into the
upper 30s to lower 40s. 18
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Once the aforementioned
Saturday front moves into the area, this will trigger another round
of active weather as another upper level low will camp out over the
W coast of Canada, spinning system after system into W WA. As one
would expect, while breaks and lulls can be expected during the long
term, none of them persist long enough to be of any merit, nor do
deterministic models find any agreement on when they might occur.
Further blurring the picture are the vast array of ensemble
solutions, although the ensemble mean keeps precip amounts generally
less than or around one-tenth of an inch. If one needed to pick a
singular day to plan outdoor activities, it seems like Sunday may be
the day to avoid as the ensemble mean seems to be favoring that day
for activity, although, as stated earlier, no particular date within
the long term period can offer any prolonged dry conditions.
Sunday will still see some benefit from the earlier dry period as
highs that day look to be the warmest of the forecast period, with
highs in the mid 50s to around 60. Otherwise, highs in the lower 50s
can be expected. 18
&&
.AVIATION...North-northwest flow will develop this evening as a
transient upper-level ridge builds over. VFR conditions will remain
this evening, but low clouds look to develop overnight which
could fall to the MVFR threshold. Can`t rule out a brief spell of
patchy fog as well, particularly for spots like KPWT and KOLM
under enough clearing prior to low cloud development but
confidence is not high. Any low clouds that form should see a
return to VFR skies later on Wednesday by 18z. However, a weak
front will track into the area with light showers which under
heavier precip could allow for additional brief instances of MVFR
observations for Wednesday afternoon-evening.
KSEA...VFR skies observed at the terminal this evening. However,
low clouds will return early Wednesday morning with possible MVFR
conditions between 12-16z. Winds look to turn south by 12z.
33/McMillian
&&
.MARINE...Low level onshore flow will ease later tonight.
Additional fronts will likely cross the waters Thursday and again
over the weekend as the pattern remains active. Small craft
advisory winds at least over the coastal waters with Saturday`s
front.
33/McMillian
&&
.HYDROLOGY...No river flooding expected in the next 7 days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 6 AM PDT Thursday for Admiralty Inlet-
Central U.S. Waters Strait Of Juan De Fuca-East Entrance
U.S. Waters Strait Of Juan De Fuca.
&&
$$
Area Forecast Discussion
National Weather Service Salt Lake City UT
359 PM MDT Wed Apr 12 2023
.SYNOPSIS...A storm system will move through the area late
this evening through Thursday morning, bringing precipitation to
northern Utah and dropping temperatures back to or below seasonal
normals. High pressure will return for the upcoming weekend.
&&
.SHORT TERM (Through 12Z Friday)...Watching a developing area of
cumulus cloud in western Utah at this hour along a weak axis of
instability ahead of the approaching mid-level trough and
baroclinic zone. Analyzed 250 J/kg CAPE running well below
forecasts from CAMs though ample sunshine and steep mid- and low-
level lapse rates likely to make up for the lack. Largely missing
any sort of moisture, as dewpoint depressions across the region
remain large, which will be the main limiting factor in this
evening`s convection. Anything that does form showers undoubtedly
will produce relatively strong wind gusts in the vicinity.
While analysis of the cold front tracks current model forecasts,
noting that the latest HRRR has backed way off on the
intensification of the front through northwestern Utah and reduced
the pre-frontal winds and overall precipitation amounts in kind.
Still expecting a brief period of moderate precipitation early
Thursday morning as this feature transits the region, but if this
latest run is a harbinger of what may come with the rest of the
00Z model suite, likely going to see total precipitation forecast
decrease greatly along the Wasatch Front and northern mountains as
a result. Additionally, a weaker cold front and more gradual
arrival of cold air paired with less intense precipitation rates
would shift a greater percentage of the total precipitation back
towards snow rather than rain. Further complicating the
precipitation type forecast is the strong synoptic lift, cold air
aloft and convective potential stemming from it driving some
period of graupel. In any case, likely to be a wet and possibly
messy morning commute for portions of the Wasatch Front, and a
much cooler afternoon on Thursday than we`ve had yet this week.
Overnight lows Thursday will return to or just below seasonal
norms behind the cold front.
.LONG TERM (After 12Z Friday)...The extended forecast period
remains largely unchanged as we creep into spring weather in the
Great Basin region. Lingering precip from the storm system in the
short term makes its way into Friday before giving way to a high
pressure ridge. Ridging will bring back clearing skies and warmer
temperatures, nearly 5-10F above climatological norms through the
weekend and beginning of the coming work week. Uncertainty grows by
midweek of a potential large scale low off the PNW coast that could
bring widespread precipitation back to Utah.
Friday morning the trough axis is expected to be through Utah thus
shutting off any main precipitation. With 700mb temperatures
remaining cold through the morning there is good potential for
orographic processes to take over and squeeze any lingering low
level moisture into some lingering snow showers over the northern
Utah high terrain. This will later on give way to the ridge growing
into the region, bringing more west/southwest flow aloft through the
weekend that will rebound 700mb temperatures. Warming aloft will
drive back clearer and sunny skies as temps settle to the ground,
promoting spring like days through the weekend and into the
beginning of the following week. Current grid values point towards
the warmest days being Sunday/Monday with low 70s in most Utah
valleys (60s Cache, 80s St. George).
Current deterministic models favor a low pressure system deepening
over the PNW coast that will grow into the region and drive
precipitation over the state by the end of the extended period.
Uncertainty remains in the exact timing of this trough to impact the
CWA but ensemble members seem to help push the favorite towards a
Tuesday/Wednesday arrival. This will also bring a cooling back to
the area that will bring us back closer to seasonal norms. How much
cooling this trough brings also leaves uncertainty in ptype but
certainty will clear up in the coming days.
&&
.AVIATION...KSLC...Varying winds from the southwest to northwest
will last through roughly 06Z. With prevailing winds from the
southwest aloft, any northwest flow would result in marginal low
level wind shear. Broken to overcast ceilings will last through the
overnight, with chances for rain then a rain-snow mix much of the
morning. Ceilings and visibility will lower into MVFR or IFR range
with precipitation around 13Z, lasting through the morning.
.REST OF UTAH AND SOUTHWEST WYOMING...A cold front will track across
northern Utah, reaching the urban corridor near sunrise. IFR or
lower ceilings and visibility are likely with snow in far northern
Utah, where other locations will mainly have rain or mixed
precipitation. MVFR or IFR conditions are likely much of the morning
for these locations. Dry conditions are expected throughout southern
Utah. The cold front will reach there during the afternoon with
southwest winds transitioning to northwest.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
Wessler/Selbig/Wilson
For more information from NOAA`s National
Weather Service visit... http://weather.gov/saltlakecity