Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/04/23
Area Forecast Discussion
National Weather Service Charleston SC
1012 PM EDT Wed May 3 2023
.SYNOPSIS...
High pressure will prevail through Friday. A cold front will
impact the region this weekend, followed by potentially
unsettled weather next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
This evening, IR satellite indicated clear conditions across the
forecast area. Latest round of observations indicated that most
of the forecast area had winds less than 5 mph, with calm
conditions inland.
With clear skies and the extremely dry air mass, this should
promote better radiational cooling than recent nights. Our min
temp forecast is a mixture of the cooler MOS, HRRR and NBM10
percent, equating to mid and upper 40s most communities inland
from US-17, with 50-57F degrees closer to the coast and in
downtown Charleston and Savannah.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Thursday and Friday: Mid-level troughing just off the Northeast U.S.
Thursday morning will weaken and shift further offshore. Ridging
will start building over the South Central U.S. on Friday. This will
lead to NW flow over our area both days. At the surface, High
pressure will build across our region Thursday, then shift offshore
later Friday. The High will be the prominent driver of our weather
through Friday afternoon, bringing dry conditions. Skies will be
mostly sunny/clear Thursday, with increasing clouds on Friday.
Models do indicate increasing moisture later Friday with PWATs
rising to around 1.25". Likewise, they indicate isolated or
scattered showers across our SC counties during the evening and
overnight hours. Hence, we have chance POPs there. QPF should be
minimal and the risk of thunder is low due to limited instability.
Our GA counties should remain rain-free. As for temperatures, low-
level thickness values support values several degrees below normal
Thursday. Though, they should recover to near normal on Friday.
Saturday: Our area will be sandwiched between troughing off the East
Coast and ridging to our west, leading to NW flow. A cold front is
expected to drop south into the region. Moisture will increase ahead
of it with PWATs around 1.5". Likewise, most models indicated
scattered showers in the afternoon, with the highest POPs likely
across our SC counties. A few rumbles of thunder are possible, but
the overall severe risk is low. There could be a decent temperature
gradient in place with highs ranging from the mid to upper 70s
across the Charleston Tri- County, rising to the mid 80s near the
Altamaha River.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Models are in good agreement showing northwest flow early next week
with a ridge located just to our west. This ridge will slowly move
towards the East Coast on Monday, weakening as it does so. The
pattern then becomes more uncertain into Wednesday. A weak area of
Low pressure may be moving away from the area Sunday into Sunday
night. Meanwhile, surface troughing appears to develop off the
Southeast coast, where it could prevail into the middle of next
week. Overall, the pattern looks somewhat unsettled with there being
low end chances of showers each day. Temperatures will be above
normal, trending higher each day.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR conditions will continue at KCHS, KJZI, and KSAV through
the 0Z TAF period. Northwest winds may gusts to 15 to 20 kts
early this evening, then winds will shift from the north around
5 kts shortly after sunset. Winds are forecast to remain much
lighter on Thursday, favoring a WSW direction between 5-10 kts.
Extended Aviation Outlook: VFR. There are low probabilities
for flight restrictions this weekend into early next week due to a
cold front and then a potentially unsettled weather pattern.
&&
.MARINE...
This evening and tonight: The broad cyclonic circulation around
low pressure near New York City and off the Delmarva early on will
give way to continental high pressure through the night. The
pressure gradient will steadily slacken, and although we begin
the period of Small Craft Advisories for all waters, including
Charleston Harbor, all headlines will come down before midnight.
West and northwest winds will still gust as high as 25 or 30 kt
early on, dropping to 15 kt and gusty during the late evening or
overnight as they veer to the N and NE. Seas will be held to
just 5 feet or less throughout due to the offshore flow, then
dropping to 4 feet or less overnight with less winds.
Extended Marine: High pressure will spread across the Southeast U.S.
Thursday, then offshore on Friday. This will bring tranquil marine
conditions both days. Though, there will be increased winds each
afternoon along the land/sea interface and in the Charleston Harbor
due to the sea breeze. A cold front will drop south through the
region this weekend, which could bring increased winds and seas.
However, neither is expected to be high enough to prompt Small Craft
Advisories. A potentially unsettled weather pattern could be in
place next week, but no significant marine impacts are expected.
&&
.FIRE WEATHER...
Thursday will still have low relative down around 23 to 28
percent, but much less wind.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...
FIRE WEATHER...
Area Forecast Discussion
National Weather Service Goodland KS
525 PM MDT Wed May 3 2023
.SHORT TERM...(This evening through Friday Night)
Issued at 323 PM MDT Wed May 3 2023
At the beginning of the short term period, the latest RAP analysis
shows the CWA underneath an upper ridge in an omega upper air
pattern with a western low over the central CA coast and an eastern
low over the Mid-Atlantic region. Current surface observations and
radar imagery report dry conditions across the CWA with a good
amount of high clouds over the CWA. Model guidance shows the CWA
remaining underneath the ridge through the remainder of the day with
a shortwave disturbance passing through the flow over the CWA during
the late afternoon and evening hours. At the surface, the CWA sees
some slight chances for light rain showers and thunderstorms during
the evening and going into the overnight hours with a surface low
near the CO/NE/WY border. Models show the southerly flow bringing in
a good amount of moisture in the 850mb level. When looking at
convective parameters, MLCAPE values look to be around 1000 J/kg
though bulk shear values stay around 20 kts during the evening.
While there looks to be rumbles of thunder possible, the environment
does not look to allow storms to become too organized to become
severe at this time which supports the SPC`s latest outlook of
general thunderstorms for the region and moving the marginal risk to
the south where higher shear values are expected. During the
overnight hours, precipitation chances look to be mainly in the
eastern counties. QPF values currently look to be a few hundredths
at most in areas that might see rainfall. Overnight low temperatures
for tonight look to be in the middle 40s to lower 50s.
On Thursday, models project the western low moving more inland
during the day with the CWA taking a mostly southwesterly flow by
the afternoon hours as the upper air ridge progresses eastward.
Another shortwave disturbance looks to pass through the flow over
the CWA during the evening and overnight hours. At the surface, the
CWA sees some chances for showers and thunderstorms once again
during the afternoon and evening hours with a surface low moving
across CO during the day and going into southwestern KS by the
overnight hours. Precipitation coverage looks to be more widespread
compared to Wednesday with this setup. When looking at the the
latest model convective parameters, MLCAPE looks to range from
between around 1000 to just over 2000 J/kg during the late afternoon
and evening hours with higher values near the KS/NE border. However,
higher bulk shear values around 30 kts at this time look to be more
south of I-70. So there looks to be a chance for isolated severe
thunderstorms with large hail and damaging winds being the possible
hazards. Will continue to monitor this in future forecasts as the
SPC`s latest Day 2 outlook does have a good portion of the CWA in a
marginal risk. The southerly flow continues to bring in warmer air
as well moisture during the day, but the expected cloud cover during
the day may not allow the temperatures be much warmer than
Wednesday`s temperatures. Expected QPF values from rainfall on
Thursday currently looks to range from a few hundredths to around
a half of an inch. Daytime highs on Thursday expect to be in the
upper 70s to lower 80s with overnight lows in the lower 40s to
lower 50s.
For Friday, forecast guidance shows the CWA between a trough to the
west and a ridge to the east keeping a southwesterly flow throughout
the entire day with another shortwave disturbance passing over the
CWA during the evening. At the surface, models show yet another
surface low in CO during the day, but have it move eastward
through the CWA during the evening hours allowing for more shower
and thunderstorm chances with better chance north of I-70. Models
currently show some differences in the exact timing and track of
this low so opting to keep the NBM PoPs at this time throughout
the day. Expected QPF looks to range from a few hundredths to
around a tenth of an inch in the northern portions of the CWA.
When looking at convective parameters, models show some higher
bulk shear values around 40 kts in the late afternoon and evening
hours with little to no CAPE seen. Not anticipating severe weather
at this time based on these forecast parameters though will
continue to monitor them. Friday`s daytime highs look to be
between the middle 70s and lower 80s while overnight lows range
between the lower 40s and the lower 50s.
.LONG TERM...(Saturday through Wednesday)
Issued at 140 PM MDT Wed May 3 2023
Southwest flow will predominate through the long term period
between a persistent trough over the western CONUS and a ridge
over the Ohio Valley. Occasional shortwaves embedded in the flow
will bring low chances for showers and thunderstorms. However,
confidence in any widespread rainfall is rather low. Severe
chances will also be limited due to overall lack of instability.
Fire weather will be a daily concern with afternoon relative
humidity values below 20 percent. Temperatures will be above
normal with highs in the 70s and 80s and lows in the 40s and 50s.
For Saturday, a shortwave trough will move from southeast Colorado
in the morning, across the area mid day and into central Nebraska
by the afternoon. If that timing continues, best chances for
showers and thunderstorms during peak heating will occur in
southwest Nebraska. Despite favorable deep layer shear,
instability is forecast to be weak in far southwest Nebraska, less
than 500 j/kg, limiting the overall severe risk should storms
develop. Further south, instability dwindles to near zero.
However, elevated to near critical fire weather will be possible
in southern areas with southwest winds forecast to gust up to 30
mph and relative humidity dropping to less than 15 percent.
For Sunday, southwest flow continues but difficult to identify
anything other than a weak ripple in the models. ECMWF might show
a bit more of a shortwave trough compared to the GFS. Either way,
upper forcing, if any at all, will be weak. A surface low will be
lingering in the northeast part of the forecast area which may
bring in some moisture to that area. Even if weak instability
manages to develop CIN may be too much to overcome. QPF is rather
spotty in the models and POPs may be a bit overdone. As for fire
weather, southwestern areas again see humidity below 15 percent,
but wind speeds are lower compared to Saturday, so may see
elevated rather than critical conditions.
For Monday, southwest flow continues and again the challenge is
identifying any weak embedded shortwaves. What instability exists,
again rather weak, is confined mainly to southwest Nebraska and
northeast part of the area. Further south, dry southwest winds
persist with no instability. Fire weather may once again be
limited to elevated in those areas due to lack of gusty winds.
For Tuesday and Wednesday, GFS really dries out the area with
stable conditions. However, the ECMWF is more active with showers
and thunderstorms both days, due to embedded shortwaves coming out
of Colorado whereas the GFS shows zonal flow and even weak
ridging. As a result, rather low confidence in precipitation
forecast both days. Elevated fire weather due to low humidity will
continue, but neither day looks particularly windy and critical
conditions appear unlikely at this point.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 524 PM MDT Wed May 3 2023
VFR conditions are expected to continue for KGLD and KMCK. Winds
gust around 20 kts throughout the first half of the night, but gusts
are expected to decrease by 3Z for KMCK and closer to 12Z for KGLD.
Starting around 16Z mid level clouds are forecast to enter the
region. There will be a chance for thunderstorms to move in from the
southwest. For KGLD, the storms could begin around 19Z, at KMCK, the
storms will move in closer to 23Z. Timing for the storms are subject
to change in future forecasts and TAFs.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...076
LONG TERM...024
AVIATION...JN/CA
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
711 PM EDT Wed May 3 2023
.SYNOPSIS...
High pressure builds overhead Thursday into Friday. A weak wave
will impact the area Saturday and Sunday. Warmer conditions
arrive early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 645 PM Wednesday...Yet another upper level shortwave, and
associated surface boundary, is moving offshore this evening.
Regional radar shows scattered showers and isolated thunderstorms
moving offshore at this time as well, in association with a zone of
better mid-level moisture. Regional RAP analysis, radar imagery, and
satellite imagery reveal another shortwave and surface boundary
moving towards the area from Virginia. While showers with this
feature may glance our far northern counties near the Albemarle
Sound this evening, a general drying trend is forecast aloft which,
consequently, should lead to a lowering chance of rain locally. For
this reason, I confined the risk of showers to the Outer Banks and
offshore over the next few hours.
Winds are beginning to decouple, and decrease, but occasional gusts
of 20+ mph will still occur between now and sunset. Assuming skies
remain mostly clear overnight, it still looks like a solid signal
for lows in the 40s away from bodies of water tonight.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
As of 3 PM Thu...High pressure building overhead and weak
subsidence aloft will keep dry conditions in place Thursday.
Deep layer WNW/downsloping flow justifies favoring the warmer,
gustier/lower RH side of guidance, with highs near 70s for most,
still almost 10 deg below normal for early May.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
As of 345 PM Wed...Low pressure riding along a stalled frontal
boundary to our south brings yet another unsettled weekend.
Drier conditions return to start the next work week while the
region gradually settles into a more summer-like pattern with
diurnally driven shower and thunderstorm activity.
Friday through Sunday...The surface high will not stay around
for long, as low pressure deepening over the central plains
early Friday aids in dragging a front across much of the
southeastern CONUS, stalling it just to our south over the
weekend. Guidance continues to improve consensus on a weak wave
of low pressure migrating along the boundary on Saturday,
overspreading precip over the region with best chances west of
Highway 17. Raised PoPs further well into chance range,
extending them into Sunday along the coast as the low deepens
offshore. Most of our FA should remain on the cool side of the
front, but if the low track shifts east enough some thunder
chances are not out of the question along and south of Highway
70.
Monday and Tuesday...Signal in guidance is for a considerable
amount of low level moisture from the Gulf of Mexico to
gradually migrate eastward towards the Carolinas through the
week with mid 60s dew points expected by Tuesday. Mid-level
ridge on Monday will favor drier conditions, before a weak
shortwave breaks down the feature on Tuesday allowing for better
chances of showers and thunderstorms. Although there is
consensus in the general pattern, considerable variance lingers
with small-scale features which could locally enhance or inhibit
day to day rain chances, and confidence in PoP forecast is lower
than average.
Temperatures will gradually increase through the period,
although briefly interrupted by cloudy and wet conditions
Saturday and Sunday with highs 5-10 degrees below average. By
the end of the period, temperatures rebound to about 5-10
degrees above normal.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
SHORT TERM /through 00z Thursday/...
As of 645 PM Wednesday...Upper level waves will continue to drop
southeast across the Mid-Atlantic over the next 24 hours as we
continue to remain in a deep, northwesterly flow aloft pattern. One
wave is moving offshore at this time, with the associated low CIGs
and SHRA moving away from the area. However, yet another wave is
just upstream across Virginia, and will move through Eastern NC over
the next few hours. This may lead to a quick renewal of low CIGs and
perhaps a few SHRA, but in general, drying aloft should lead to a
lower risk of low CIGs and SHRA. Winds will continue to subside as
we lose daytime heating and mixing, and as the pressure gradient
relaxes some, but it will still be gusty for another 1-2 hours. For
S to N oriented runways (ie EWN), a crosswind component/impact will
also linger for another 1-2 hours. High pressure moves overhead on
Thursday, with an even weaker pressure gradient, and lower winds
compared to today. Diurnally-driven cumulus are expected again on
Thursday, but VFR conditions are expected to prevail. Lastly, late
in the day Thursday, some short-term guidance are hinting at the
potential for a "backdoor" front to slide south into the Northern
Outer Banks as another upper level wave slides by to the north. If
this does materialize, there would be a north or northeast wind
shift in that area.
LONG TERM /Thursday night through Monday/...
As of 345 PM Wed...VFR conditions are expected through the
period with lighter winds tomorrow and Friday as high pressure
takes control. Next period of inclement flying conditions is
Saturday into Sunday as a wave of low pressure riding along a
stalled frontal boundary overspreads low clouds and rain for
much of eastern NC. Terminals in the coastal plain and Crystal
Coast are favored to see the worst conditions on Saturday. By
Sunday, the coastal plain will begin to clear out but poor
conditions will likely linger along the coast for most of
Sunday.
&&
.MARINE...
SHORT TERM /through Thursday/...
As of 330 PM Wed...Gusty winds continue near shore this
afternoon, with the gradient continuing to tighten further
across the waters in advance of an approaching shortwave. W
winds peak early evening around 20-25 kt, with some occasional
gusts approaching 35 kt possibly mainly near the western wall of
the Gulf Stream. Despite the offshore direction, winds will
also be strong enough to build seas to around 5-7 ft beyond
about 15 nm offshore in rough windswell.
Then, later this evening and overnight, the gradient weakens,
and winds gradually diminish. SCAs come down for the inshore
waters through the morning, lingering through sunrise for the
coastal waters as windswell steadily diminishes. Mainly light to
moderate WNW winds then prevail Thursday as high pressure builds
into the area.
LONG TERM /Thursday night through Monday/...
As of 355 PM Wed...If there is any potential for a return to
advisory criteria, it is late Saturday into Sunday, mainly for
the outer waters of Raleigh Bay as backswell from a departing
low moves into the area from the northeast. The local NWPS run
appears to be slightly too aggressive with wave heights
associated with this swell, and favored the more subdued
WaveWatch and NBM guidance keeping seas below 6 feet.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for AMZ131-135-
156-158-230-231.
Small Craft Advisory until 3 AM EDT Thursday for AMZ136-137.
Small Craft Advisory until 11 AM EDT Thursday for AMZ150-152-
154.
&&
$$
SYNOPSIS...MHX
NEAR TERM...RM
SHORT TERM...CB
LONG TERM...MS
AVIATION...RM/MS
MARINE...CB/MS
Area Forecast Discussion
National Weather Service Pocatello ID
247 PM MDT Wed May 3 2023
.SHORT TERM...Tonight and Thursday
An upper low centered off the central California coastline will soon
bring a prolonged period of active weather to eastern Idaho starting
tomorrow and continuing into weekend. Afternoon satellite imagery
shows mid and high clouds associated with the low gradually
streaming over the region. A shortwave will break off from the
parent low later tonight and as that feature approaches the region,
our pleasant, dry weather will come to an end for awhile. Hi-res
model guidance shows the first wave of precip moving out of northern
Utah during the overnight hours but the best chances will begin
around daybreak tomorrow and overspread the region throughout the
morning hours tomorrow. Showers with some thunderstorms will be
possible throughout the day with the best chances of tstms during
the afternoon and evening hours. While QPF totals are not overly
impressive by themselves, 0.1-0.5 inches, this falling on top of a
ripening snowpack across the higher terrain will lead to continued
flooding concerns around the area. Central Mountains will likely see
the highest rain totals with favorable upslope enhancement pattern.
Lower totals, closer to 0.1-0.2 in the Snake Plain, will still lead
to continued flooding concerns along rivers currently flooding as
they are already running on the higher side. See the hydro
discussion below for more specifics. As far at temperatures are
concerned, things will be noticeably cooler tomorrow with increased
cloud cover and rainfall, generally lower to mid 60s in the valley
and 50s across the high country. McKaughan
.LONG TERM...Friday through next Wednesday.
Our active weather pattern is still on track to continue through the
weekend and into early next week with more precipitation ahead
thanks to wave after wave of energy moving through the area. One
round on Friday will bring wind gusts of 25 to 35 mph, more rain,
storms, and snow. Snow levels will be dropping Friday night into
Saturday morning from around 7500 to 8000 feet down to around 6000
to 7000 feet, so this will bring some more snow to the higher
elevations of the Central Mountains, Bear River Range, and near the
Tetons with snow levels staying around the 6500 to 7500 feet range
through the weekend. By Saturday night, the NBM shows the 75th
percentile 48 hour snow totals in the Central Mountains and
Centennial Mountains reaching 6 to 8 inches. Those same totals are
much lighter in the Bear River Range and near the Big Hole
Mountains, coming in closer to 1 to 3 inches. At the lower
elevations, there is a 10 to 25 percent chance of QPF greater than a
half inch in that same time frame, with the 75th percentile amounts
ranging from 0.30 to 0.50 inches. Afternoon highs through the
extended forecast period hold fairly steady, in the upper 40s to low
60s, with most running about 5 degrees below average for this time
of the year. Saturday and Sunday look to be the coolest days before
we gradually begin to warm up early next week. Overnight lows will
be in the 30s for most of the Magic Valley and Snake Plain with
temperatures falling below freezing through the rest of the higher
elevations. Both the ECMWF and GFS show showers and thunderstorms
generally continuing on and off through the weekend and into early
next week as wave after wave keeps our pattern wet and unsettled.
The GFS and ECMWF handle these waves in slightly different manners
as we round out the weekend and head into early next week, but both
show more rain and storms Monday into Tuesday. Models show another
10 to 30 percent chance of greater than a quarter of an inch QPF for
the entire area again with a less than 15 percent chance of half an
inch of QPF outside of the mountain peaks. Look for wind gusts to
pick up a bit with this push of moisture with gusts 15 to 25 kts. We
may see a small, brief respite in the middle of next week as weak
ridging builds in over the area. Moore
&&
.AVIATION...18Z Wednesday through 18Z Thursday.
We continue with VFR conditions throughout the rest of the afternoon
and evening. Winds will be light for the most of today with gusts up
to 20kts at BYI and SUN. Mid to upper level clouds will be working
their way into the area as the slow-moving low that has been sitting
off the coast of California gradually pinwheels up towards us. As it
moves in, rain chances begin to increase after sunset, with hi-res
models showing showers and potentially a few thunderstorms around
midnight at BYI and SUN first. Currently, guidance is showing about
a 10 percent or less chance of thunder at SUN and PIH tonight, with
a 10 to 30 percent chance at BYI. Eventually rain will overspread
all sites on Thursday with enough instability for thunderstorms,
too. At this time, both the HRRR and NAM show brief drops in VIS
down to borderline MVFR/IFR levels as rain moves through late
Thursday morning/early Thursday afternoon. Moore
&&
.HYDROLOGY...Well above normal daytime temperatures and temperatures at night
(for most areas) staying above freezing continue to bring gradual to
steep increases on area rivers and creeks this afternoon. Though
temperatures do drop Thursday, precipitation Thursday through the
weekend will aide in snowmelt and all rivers/creeks should see
increased flows.
The Flood Watch for sheet flooding continues in the Stanley Basin,
the Wood River Basin, and the eastern and southern highlands, with
the exception of the Bear River Range. The lower elevations of the
Big and Little Lost River basins including Arco, Howe, and Mackay
have been removed from this watch.
A Flood Watch for the Bear River near the Idaho-Wyoming border
continues.
Flood Advisories are in effect for Franklin and Bear Lake Counties.
Flooding in these counties has been characterized as nuisance
flooding, covering some roads to the point where they may be closed.
Flood Warnings have been issued for or continue in these locales:
Bannock County: The Rapid Creek through Inkom is just one of many
locations suffering from flooding not directly due to the
Portneuf River.
Franklin and Oneida Counties: Flooding of creeks and streams,
especially Devil Creek and Deep Creek through Malad City is expected
in the coming days. Other creeks and streams will continue to run
high and small reservoirs in the area run the risk of overtopping.
Portneuf River: All portions of this River are at least in minor
flood stages, with the stretch running through Pocatello at a higher
level (moderate). This is expected to worsen through Sunday. The
Marsh creek basin, especially by Downey, is experiencing flooding
and was added to the flood warnings last night.
Little Wood River system: The High Five Creek near Carey has reached
minor flooding stage.
Big Wood River: The stretch running through the town of Hailey has
reached minor flood stage.
All of these areas will continue to have flooding and likely worsen
by late Thursday into the weekend aided by rainfall. The Big Wood
and Portneuf rivers are the rivers to see the most rises due to
rainfall.
Some areas we continue to monitor that are close to flood stage are
Willow Creek near Ririe, the Blackfoot river above the Blackfoot
reservoir, the Bear River at the Idaho-Utah border, the Bear river
at the Idaho-Wyoming border, and the Antelope Creek on the Lost
River system.
Wyatt/Moore
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday afternoon for IDZ058-059-061>067-072-
073-075.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
459 PM MST Wed May 3 2023
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
Low pressure off the west coast will move eastward Thursday,
resulting in a continuation of the breezy conditions and a cooling
trend. Thereafter, the low will weaken across the intermountain
West, giving way to a gradual warming trend and a likely return to
above normal temperatures by early next week.
&&
.DISCUSSION...
Latest water vapor imagery reveals a large cyclonic vortex off
the west coast. Ahead of this system, southerly flow predominates
along with below normal temperatures closer to the low across
southeastern California. Meanwhile, the pressure gradient remains
relatively tight and breezy/windy conditions will remain the
primary weather concern the next few days.
Latest HREF ensemble max indicates the potential for the
strongest wind gusts will be across southeastern California
tonight and a Wind Advisory remains in effect for these areas.
Gusts as high as 50 mph will be possible, even across the Imperial
Valley. Further east, high-res guidance including the HRRR
suggest gusts as high as 25-30 mph will still be possible across
the Valley late this afternoon and this evening.
The aforementioned low pressure system will drift eastward
Thursday. This will mainly affect temperatures, with highs
struggling to reach the 80 degree mark across portions of the
lower deserts, particularly west of Phoenix. Latest suite of
GEFS/ECMWF ensembles indicate the low will weaken across the Great
Basin Friday, resulting in a gradual warming trend, though the
presence of the negative height anomalies will translate into a
continuation of the below normal temperatures through early next
week.
Latest model cluster analysis indicates a reasonable amount of
uncertainty developing by early next week. General trend in
temperatures is upwards, however lower probability clusters
suggest a 40 percent chance of additional short-wave troughs
enhancing afternoon breeziness and tempering the warming.
&&
.AVIATION...Updated at 2358Z.
South-Central Arizona including KPHX, KIWA, KSDL, KDVT:
Breezy W to SW winds, gusting upwards of 20-25 kts, will continue
into the early evening hours before subsiding. Winds are expected
to switch around to a SE component briefly overnight, though some
variability is possible. Winds pick up out of the S by mid morning
tomorrow before veering toward the SW with gusts increasing
upwards of 20-25 kts by tomorrow afternoon. Otherwise, FEW, to at
times SCT, clouds aoa 10 kft will continue throughout the period.
Southeast California/Southwest Arizona including KIPL and KBLH:
Strong westerly winds will continue at IPL through the period.
Wind gusts at IPL will increase upwards of around 35 kts this
evening, which could lead to some blowing dust that could result
in reduced visibilities at times. Winds are then expected to
weaken some, but gusts to around 25 kts will remain possible. At
BLH, breezy SSW winds will persists with gusts to around 20-25 kts
throughout much of the period. Otherwise, a few clouds aoa 10 kft
and FEW-SCT high clouds will continue throughout the next 24
hours.
&&
.FIRE WEATHER...
Breezy to occasionally windy conditions can be expected the next
few days across the Desert Southwest as a low pressure system off
the west coast moves eastward Thursday and then weakens across
the Great Basin Friday. Temperatures will remain several degrees below
normal Thursday and Friday. Meanwhile, Min RHs will generally
remain above 15 percent each afternoon, particularly across
southeastern California and closer to the area of low pressure.
A gradual warming trend is then anticipated through the weekend
into early next week. MinRH values through Saturday will generally
range between 15-20%, declining to between 10-15% by Sunday and
Monday. Overnight recoveries through Saturday will be fairly good
to between 40-70% and gradually deteriorate into early next week.
&&
.HYDROLOGY...Updated 245 AM MST 5/3/2023
Salt: Releases from Granite Reef Dam once again have risen to near
1000 cfs due to increased runoff from more additional snow melt
upstream along the Verde Basin. If additional rises continue
through the next couple of days, another Flood Warning may be
needed downstream between the dam and Tempe Town Lake.
Gila: Flow in the Gila River continues to travel downstream through
Yuma County as water releases from Painted Rock Dam continue.
Releases from Painted Rock Dam remain above 3000 cfs. Continued
releases from the dam will lead to inundation of downstream
unbridged river crossings through Yuma County. Several unbridged
roads in Yuma County have already reportedly been closed due to
flooding. Flood warnings remain in effect downstream of Painted Rock
Dam to the Colorado River. The latest USGS gauge observation along
the Gila River near Dateland recorded a depth around 8.9 feet, which
is above action stage (8 feet) and just shy of minor flood stage (9
feet). The latest forecast from the CBRFC indicates that flow in the
river will remain above action stage through at least the next week.
The USGS gauge closer to the town of Yuma, near Dome, shows flows
continuing to increase with a current flow height near 19.8 feet,
with the latest forecast from the CBRFC indicating flows
approaching 20 feet, which will be at action stage, through the
next week. Thus, Flood Warnings along the Gila River remain in
effect through at least May 7th and more likely than not will
need to be extended.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT Thursday for CAZ562.
Wind Advisory until 3 AM PDT Thursday for CAZ563-566-567.
&&
$$
DISCUSSION...Hirsch
AVIATION...Smith
FIRE WEATHER...Hirsch/Lojero
HYDROLOGY...Lojero/Smith
Area Forecast Discussion
National Weather Service Raleigh NC
900 PM EDT Wed May 3 2023
.SYNOPSIS...
Deep low pressure will drift eastward over the Northeast and Mid
Atlantic states through tonight, then push offshore Thursday. A warm
front will lift northward into the Carolinas before stalling out on
Friday, then low pressure tracking along the front will bring
unsettled weather for Friday night through Sunday.
&&
.NEAR TERM /TONIGHT/...
As of 900 PM Wednesday...
The upper low was located over the Delmarva region at 00Z, with the
most amplified shortwave within the cyclonic flow now well off the
NC/VA coast. The associated mostly dry cold front was well south
our area over SC. Showers and even a few thunderstorms that continue
to rotate around the upper low are confined to areas over the
central Appalachians and are generally dying off as they move into
SW VA.
Expect continued clearing of skies over central NC overnight,
although a channel of upper moisture upstream over the Midwest could
result in some NW flow orographic cirrus over the Piedmont late
tonight based on the pattern and mostly RAP guidance. This should
not be dense and have little sensible impact.
High pressure over the mid-Miss Valley is forecast to build east and
around the mountains tonight, which combined with weakening winds in
general and radiational cooling could cause winds to go nearly calm
across mainly the southern Piedmont late tonight. This suggests
temps on the cooler side of guidance and with a low level thickness
of around 1325m forecast by 12z could result in some upper 30s for a
couple of hours. Confidence is only medium and no frost impacts are
expected. Other areas will still be quite chilly in the low to mid
40s...10+ degree below normal.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 210 PM Wednesday...
The stacked low will be offshore by Thursday, but it will still be
in close enough proximity to keep a northerly component to the wind,
which despite mostly sunny skies, will still result in below normal
temperatures. However, highs should be 5-10 degrees warmer than
today, ranging from the mid 60s in the northeast to the mid 70s in
the southwest. The more noticeable change to the forecast will
likely be the reduced wind, with wind gusts only as high as 20 mph
compared to several days of wind gusts reaching 30-40 mph.
Cloud coverage will increase slowly Thursday night in advance of the
next system approaching the area. Despite a light northerly wind,
the additional cloud cover should help to keep overnight lows a
light warmer, ranging from the mid 40s to the low 50s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY...
As of 235 PM Wednesday...
Fri-Sat night: Still appears to be a decent chance for rain Fri
night and esp Sat, based on output from recent deterministic model
runs and ensemble systems, although the precise precip placement and
amounts have shown enough run-to-run variability to warrant reduced
forecast confidence. The blocking mid level ridge now extending from
MT to TX will deamplify and broaden as it shifts E into the Miss
Valley by the start of the weekend. One particular perturbation
sourced from the low now off the CA coast is expected to top the
ridge, passing through the central Miss Valley before tracking into
the Carolinas Fri night/Sat. The Nwly upper jet core situated over
NC early Fri will shift ENE and offshore, and the enhanced lift in
its right entrance region in tandem with the wave`s arrival should
prompt surface low formation along the strengthening NW-to-SE-
oriented surface front over the Carolinas. Forecast PWs remain above
climo with these recent runs, with 1-1.5" values spreading well NNE
into NC assisted by a shot of stronger SW 850-700 mb flow, and this
stronger low-mid level flow riding up and over the tightening low
level boundary should set the stage for overrunning rain. While
models have been wavering with the position (and even presence) of a
local swath of heavier precip, most continue to show at least a
tenth or so of measurable rain over nearly the entire area, although
the NBM probabilities of measurable rain remain around or just under
50%. After dry weather and increasing clouds Fri, will bring pops
into the W Fri night, spread them areawide Sat before gradually
pushing them out of E sections Sat night. Will keep highest pops at
good chance, highest over the W and S near the best moisture and
surface boundary, peaking Sat from mid morning through mid
afternoon. Thicknesses start to rebound with diminishing CAA, but
increasing clouds will hinder the temp rise somewhat Fri. Expect
highs mostly in the 70s followed by lows in the 50s except upper 40s
far N. With above-climo pops and high cloud cover Sat, will hold
onto below normal highs in the 60s to around 70. Lows upper 40s to
mid 50s Sat night.
Sun-Mon: Still quite a bit of uncertainty for this time period,
given a weakening low level flow, and increasingly diffuse surface
frontal zone, and the potential for additional minor waves aloft to
dive SSE over the Mid Atlantic region within the weakening mid level
Nwly flow. The op GFS and ECMWF show lingering light precip in the
E Sun, with another round of heavier showers across the N and E late
Mon/Mon night, however with weakening flow through the column and
low confidence in the presence of any CAPE, will maintain just
slight chance pops at most, as suggested by the NBM. Similar to the
model precip depiction, their thicknesses and thus temps are also
all over the place, so will hew close to climo, perhaps just a bit
cooler as the air mass modification continues under periods of
clouds.
Tue-Wed: We`ll be back in the warm sector midweek with weak low to
mid level flow, gradual warming/moistening of the lower troposphere,
and a persistent frontal zone sitting over W NC. The absence of
distinct features to force ascent or to focus precip results in
lower confidence in forecast details, however it does appear that
we`ll trend back toward more typical spring-like weather, with daily
chances of showers and storms primarily in the afternoon through mid
evening. Thicknesses continue to trend upward and above normal,
supporting highs mostly in the 80s both days. -GIH
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
As of 705 PM Wednesday...
VFR conditions will prevail through the 24 hour TAF period. Evening
nwly gusty winds will cease within the next couple hours leading to
5-10kt winds throughout the night. Winds above the inversion will
increase to 25-30kts around 2k feet overnight, mainly 00-09z across
the northern tier TAF sites. Guidance suggest spotty/sporadic 30-
35kts at this level which would lead to marginal LLWS criteria with
best chance around RWI from 03-06z, but confidence is too low to
include in 00z TAF package. Low pressure finally moves east over the
Northern Atlantic Thursday morning leading to noticeably weaker
surface winds and gustiness, with only sporadic 15kt gusts possible
during the early morning hours as the surface inversion breaks.
-Swiggett
Outlook: High pressure will allow for dry VFR conditions to continue
into Friday, but there will be a chance (30-50%) for restrictions
and showers at all sites Friday night through Saturday night. There
will be just a slight chance (15-20%) of showers and restrictions
Sunday through Monday. -Green
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...BLS
SHORT TERM...Green
LONG TERM...Hartfield
AVIATION...Swiggett/Green