Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/31/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
850 PM CDT Tue May 30 2023
.UPDATE...
Issued at 846 PM CDT Tue May 30 2023
Watching convection across western SD, especially over southwest
SD where better instability and shear exist. Some of this
activity looks to bleed into the southwest counties over the next
few hours, potentially remaining on the strong side with gusty
winds being the main threat. Made some adjustments to PoPs to
account for this, and may have to raise the southwest even more if
current activity holds together like latest runs of the HRRR are
suggesting.
&&
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 251 PM CDT Tue May 30 2023
Weak southwest flow will continue tonight and into Wednesday. A few
cu have popped up in the eastern portion of the forecast area,
otherwise pretty quiet so far today. Lack of any forcing or shear to
support growth evident. Activity from western SD and NE will move
into the Missouri River valley and west this evening bringing in
small chances of thunderstorms through 06Z tonight.
Deterministic models are in fair agreement of a small shortwave to
move up from the intermountain west tonight and into eastern SD
Wednesday. This will be the focus of the next round of thunderstorms
for the region. However, with the weak shear aloft it will be hard
to get anything organized for a long period of time. A few pulse type
storms likely however. SPC only has area in general thunder as well.
Pops may be on high side for Wednesday, but still expect a good
portion of the are to get wet.
Temps will remain above normal for late May.
.LONG TERM...(Thursday through Tuesday)
Issued at 251 PM CDT Tue May 30 2023
The main forecast challenge in the extended revolves around
precipitation chances. The upper level pattern will feature ridging
to the east and a low pressure trough over the Rockies Thursday,
with the high to the east then meandering its way back to the west
Friday, and becoming the main feature over the Northern Plains
through the remainder of the period.
At the surface, the pattern of high pressure to the east and low
pressure to the west will be in place through the entire period,
with southerly flow bringing warm and moist air into the region. The
warm temperatures and high dewpoints will lead to periods of fairly
unstable conditions each day, along with the potential for scattered
showers and thunderstorms each afternoon and evening, with quieter
conditions during the overnight hours. Therefore, much of the
extended period continues to be riddled with slight chance to chance
POPs.
High temperatures will be mainly in the 80s through the period, with
overnight lows in the lower to mid 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 639 PM CDT Tue May 30 2023
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are forecast through the TAF period. However,
threat for isolated -TSRA/TSRA or -SHRA/SHRA exists this evening
for KMBG/KPIR, then later in the TAF period for KABR/KATY. TEMPO
MVFR VSBY is possible in any heavier downpours, but confidence in
location and overall limited coverage prevents inclusion in TAFs
at this point. Will await any development and/or more immediate
impactful proximity to a TAF site before including TEMPO groups.
Will stick with VC mention at this time.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TMT
SHORT TERM...Scarlett
LONG TERM...Parkin
AVIATION...TMT
Area Forecast Discussion
National Weather Service Denver/Boulder CO
725 PM MDT Tue May 30 2023
.UPDATE...
Issued at 720 PM MDT Tue May 30 2023
It took a while, but we finally have seen some convection develop
across far northeastern Colorado this evening. While we haven`t
seen severe reports from any of these storms yet, the severe
threat should continue for the next couple of hours given a
favorable environment as they slowly move to the north and east.
Have made a few minor updates to the grids this evening and
overnight but otherwise the forecast is largely in good shape.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 206 PM MDT Tue May 30 2023
For the rest of this afternoon and evening, observations are
showing dew points in the teens and 20s over the mountains.
Precipitable water values are under a third inch and CAPE is less
than 300 J/kg. With this said, any showers or storms that form
here should be weak. Along the Front Range Urban Corridor, dew
points range from the upper 30s south to lower 50s north. CAPE is
500 J/kg south to 1000 J/kg north. Over the plains, dew points are
in the 50s with CAPE of 1000-1800 J/kg. As convection shifts
eastward off the higher terrain and across the plains, storms will
increase in coverage and intensity. Raised PoPs earlier across
the plains for this. Shear remains limited with 0-6km bulk shear
only 20-25 knots. However, like past days, the stronger storms
will be capable of large hail. The Convective Allowing Models
(CAM) show the storms coming together and producing a line over
the eastern plains. Main threat from the storms will then
transition from hail to strong winds. Storms will progress east
and exit Colorado during the late evening hours.
Closed low off the southern California coast will track eastward
into Arizona on Wednesday. Ahead of the low over Colorado, flow
aloft will back from the southwest to south. Low level flow,
roughly below 650mb turns southeasterly and will transport moist
westward into the foothills. The initial batch of storms that form
over the higher terrain Wednesday afternoon will be stronger with
heavy rain and small hail. RAP MLCAPE early Wednesday afternoon
reaches 1000- 1500 J/kg along the I-25 Corridor and into the lower
foothills. Over the eastern plains, MLCAPE climbs to 1500-2500
J/kg. Like previous days, shear isn`t that great with 0-6km bulk
shear around 25 knots. Would expect some severe hail and winds
with the strongest storms along the I-25 Corridor eastward across
the plains.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 300 PM MDT Tue May 30 2023
Moisture and rain will certainly not be lacking during the long
term period. An upper level trough will move over Colorado from
the Desert Southwest and will park itself there through the
weekend. As this happens, persistent lee cyclogenesis over the
high plains of Colorado and New Mexico will consistently draw in
moisture from the Gulf of Mexico. Precipitable water values will
be quite high, likely above 0.8" at KDEN and possibly above 1".
This would be near the max moving average on the SPC sounding
climatology page. With weak forcing aloft from the trough, upslope
low level flow, and abundant moisture, there are likely PoPs
basically every day during the extended. Unfortunately, there are
little details that can be provided about the forecast since the
coverage and intensity of the showers and storms that form each
day will be dependent on the amount of cloud cover and showers
that are around in the morning. The more cloud cover and rain
there is in the morning, the less intense the rain will be in the
afternoon. The days that have sunshine in the morning, could have
severe weather and intense, heavy rain producing storms.
Thursday and Friday will have the best chance at sunny skies in
the morning. Weak to moderate instability will develop across the
plains and storms will form each afternoon. The shear will be
lacking as winds on Thursday will be from the south throughout the
troposphere and may even have backing flow on Friday. Therefore,
severe weather will be limited or nonexistent.
On Saturday and Sunday, it appears likely that low clouds will
exist throughout each day. This would greatly limit the
instability and could lead to light to moderate rain rates as
opposed to heavy rain rates. The thing that will need to be
watched is the potential for warm rain processes with deep upslope
flow. Southeast winds throughout the troposphere may exist so the
mountains and foothills could receive the heaviest rain totals.
Monday and Tuesday will have a bit more sunshine for instability
to form develop. It is hard to say with confidence whether a heavy
rain threat will still exist these days but the precipitable water
values will remain high. Therefore, likely PoPs are in the
forecast.
Otherwise, high temperatures will remain below normal with near
normal low temperatures. The high moisture values will keep fire
weather conditions low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 535 PM MDT Tue May 30 2023
Most of this afternoon`s convection has dissipated in the past
couple of hours, but a few showers are still noted across the
western half of the metro. Some weak outflow - leading to
variable/gusty winds - will be possible through 01 or 02z,
primarily at BJC/APA.
Once this activity fades, we should see a return to normal
drainage wind patterns overnight, with easterlies expected again
tomorrow afternoon. Another round of showers/storms is likely
tomorrow, with a bit more coverage compared to today. The main
threat will be variable/gusty winds, but briefly heavy rain and
reduced ceilings/visibility will also be possible in any stronger
storms.
&&
.HYDROLOGY...
Issued at 206 PM MDT Tue May 30 2023
The storms over the burn areas today are expected to be on the
weaker side due to limited moisture. This should keep the flood
threat close to none. Better moisture moves into the foothills and
mountains Wednesday. This will increase the flash flood threat to
limited. The strongest storms expected to produce more than a
third inch of rain in 15 minutes.
With ample moisture in place throughout the extended period, there
will at least be a limited threat of flash flooding in the burn
areas each day. There will likely also be a couple days with an
elevated threat but it is unclear which days will have the highest
threat. We encourage people with interests in the recent burn
areas to follow the forecast closely through the weekend as it
could be a period with flash flooding. In addition, there may be a
flash flood threat across the plains if there is enough
instability.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Hiris
SHORT TERM...Meier
LONG TERM...Danielson
AVIATION...Hiris
HYDROLOGY...Meier/Danielson
Area Forecast Discussion
National Weather Service Des Moines IA
637 PM CDT Tue May 30 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Tuesday/
Issued at 232 PM CDT Tue May 30 2023
Key Messages:
-- Summery pattern with warm conditions, isolated to perhaps
scattered storm chance peaking in the afternoon/evening
Details: Cumulus clouds have been developing since late this morning
over central Iowa and have observed focus in isolated development of
storms from north central Iowa into southeast Nebraska/northwest
Missouri over the last hour. This area is where there is currently a
weak shortwave trough passes through and this coincides with a
moisture plume in the 850-925 mb layer. The storm near Fort Dodge at
midday had small hail and sub-severe gusty winds as it formed in an
environment of uncapped 1500 J/kg MLCAPE with no quantifiable deep
layer or effective shear on the 18z SPC mesoanalysis. Proximity
forecast soundings show the very weak flow through the column and
dry air near and above 500mb is likely also impeding sustained
development such that GOES-East clean IR imagery is showing
warming cloud tops. The weak flow coupled with surface dewpoint
depressions on the order of 15-18C with soundings showing an
inverted V sounding could lead to additional gusty winds,
especially if dry air entrainment into the column or subcloud
layer evaporation occurs that could bolster momentum transport to
the surface. As it stands now, 6z RRFS and the latest HRRR and a
few earlier morning HRRR runs show wind gusts sub-severe with the
latest in the 35 to 40 knot range. These isolated storms will be
slow moving in the weak flow and very localized heavy rainfall
will be possible. Deterministic models from the 6z run have shown
rain totals in the 3 to 4 inch range, but a few 12z models have
settled back to 2-3 inches. The 12z HREF localized probability
matched mean continues to show 2"+ bullseyes. While there is a
strong signal for sub-county localized heavy rainfall, the
location of which county is highly variable. While a few storms
may linger over northern or western Iowa, there should be a
decrease of activity into this evening as the boundary layer
stabilizes.
Overall, the pattern from the middle of this week into this weekend
will evolve as the ridge over the northeastern US will retrograde
back into the middle part of the country, which will turn our
surface flow from southerly to easterly. While there will be ridging
overhead, the sensible weather will remain largely the same with
warm days and diurnally driven isolated to perhaps scattered
thunderstorms with little in the way of an identifiable forcing.
These storms will be mainly sub-severe, but lightning and localized
heavy rainfall are likely as well as perhaps small hail and gusty
winds given the persistent weak flow, inverted V soundings, and slow
storm motions. Next week, there is ensemble agreement on a trough
dropping equatorward through the Quebec province into the
Northeastern US and eastern Great Lakes that may send another back
door cold front toward or perhaps into our region.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 637 PM CDT Tue May 30 2023
An area of thunderstorms is moving across central Iowa with
impacts exiting KFOD and moving into KDSM just prior to 00z.
Expect to see gusts over 25 kts ahead of the line followed by a
period of TSRA. The line has weakened with time and expect that
trend to continue as daytime heating quickly drops off. It is
anticipated that this line of convection will dissipate before
reaching KALO/KOTM, but will continue to monitor for trends as
needed.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...Hagenhoff
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
617 PM CDT Tue May 30 2023
.Discussion...
Issued at 216 PM CDT TUE MAY 30 2023
Key Messages..
- Isolated thunderstorms this afternoon with gusty winds.
- Thunderstorms Wednesday morning, potential for pockets of
moderate to heavy rainfall across portions of eastern Kansas and
western Missouri. Isolated flash flooding concerns.
- Warm, above normal temperatures through the week.
- Periods of showers and thunderstorms through the end of the week
Detailed Discussion...
The Rex Block to the east is not expected to budge much over the
next several days, leaving upper level flow across the central U.S.
rather weak, save for some open H500 short waves potentially
clipping from the west. From the boundary layer through the mid-
levels, modest southerly return flow will keep moisture up and
boundary layer temperatures above normal through the week.
For today, some recovery can be expected through the afternoon, as
clouds continue to clear from earlier convection and dew points
remain in the mid 60s. Mid-level water vapor imagery paints the
picture well, with the advance of a short wave trough lifting across
the shallow ridge built from the Trans Pecos and along the CO/KS
high plains. This will be the focusing mechanism for a cluster of
strong to severe thunderstorms this afternoon in CO/KS/NE. For the
MO/KS region, an axis of weak boundary layer convergence persists on
the trailing end of the surface trough associated with the lee ward
side of the upper trough and the lifting short wave across the
boundary waters. This will be a focus for widely scattered storms
late this afternoon into the evening, a few of which may have some
gusty winds.
Overnight, concerns for slow moving convection along the MO/KS
border region continues to grow. Run to run consistency persists in
the CAMs for pronounced isentropic ascent and low level convergence
through sunrise, Wednesday. Expect a cluster of storms to develop
through daybreak along the border, including the KC Metro. With
pwats around 1.30in pooled across the region, and given efficiency
of storms this morning, pockets of moderate to heavy rainfall are
likely. Even with much of the region remaining in moderate to
severe drought, isolated flash flooding cannot be ruled out. How
quickly rain ends will depend on overnight persistence and
evolution of convection across NE/KS. Current expectations is for
convection to clear through midday as the H500 short wave lifts
northeast across Nebraska.
For the remainder of the week, the unsettled pattern persists, with
warm temperatures and near daily scattered shower and thunderstorm
chances.
&&
.Aviation...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 613 PM CDT TUE MAY 30 2023
Complex of storms moving east from eastern KS may impact southern
metro including IXD.Main concern with this weaking complex is
gusty winds and brief heavy rainfall. HRRR continues to sugges
convection developing along lingering convergence line after 09Z
tonight. There is less consistecy among other model solutions, so
have limited the amount I have lowered ceilings and vis with 00Z
issuance. Will keep a close eye on this for next issuance.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Kurtz
Aviation...BT
Area Forecast Discussion
National Weather Service Peachtree City GA
756 PM EDT Tue May 30 2023
...New 00Z Aviation Discussion...
.SHORT TERM...
(This evening through Wednesday)
Issued at 300 PM EDT Tue May 30 2023
The low pressure system located off the coast of North Carolina
continues to drift northward along the Mid-Atlantic coast allowing
for a wedge of slightly cooler than average air to infiltrate
northeast Georgia. The wedge front has surged across much of the
forecast area and remains draped across our southwestern counties.
At the time of this writing, a few isolated showers have begun to
pop along the coast and eastern Georgia. The CAMs suggest a few
isolated showers will be possible across the area this afternoon and
evening, though the HRRR seems to have the best handle on the
current radar trends. If showers and thunderstorms get going this
afternoon, they will be primarily cold pool driven propagating east
to west as the wedge continues to establish itself. The best
locations for rain chances will be across eastern and northern
Georgia today, though coverage is expected to be isolated at best.
With QPF less than a tenth of an inch, any showers/storms that get
going are not expected to be particularly efficient rainmakers. A
general thunderstorm risk has been appropriately diagnosed by SPC as
upper level support is lacking. With SBCAPE around 750 J/kg this
afternoon and evening, there will be enough instability to support a
few thunderstorms, but no severe weather is anticipated.
As a low in the northern Gulf Coast develops this afternoon and
evening, moisture throughout the atmospheric column will gradually
increase over central Georgia through Wednesday. This will help
bring the chance for afternoon scattered thunderstorms tomorrow
afternoon as this moisture overruns the wedge. A general
thunderstorm risk is in place again over the forecast area and
widespread severe weather us not expected at this time. Showers and
thunderstorms are expected to primarily be focused across central
Georgia generally south of I-20 and across the north Georgia
mountains. Max high temperatures today and tomorrow will be slightly
below average in the mid 70s and mid 80s, but will be kicking off a
warming trend that will extend into the long term forecast.
KAL
&&
.LONG TERM...
(Thursday morning through next Monday)
Issued at 300 PM EDT Tue May 30 2023
Maintaining a rather uneventful longterm outlook through at least
Monday morning. Upper level flow will continue to remain light as
jet streaks remain over the GoM. Wedging persists through at
least the weekend as a combination of the slow moving surface low
off the Carolinas and a High over the Northeast drive
Northeasterly flow. Light forcing from the wedge may be sufficient
for isolated scattered convection. However, temperatures should
remain at or just below normal with highs in the mid to low 80s
for much of the region. Moving into the weekend, the wedge begins
to break down as the low off of the East Coast weakens and moves
out. Temperatures on Saturday and Sunday will begin to climb, with
highs reaching into the upper 80s and possibly the low 90s. The
potential for diurnally driven convection continues through this
time. For Monday and Tuesday, the focus moves to moisture
availability. One of two general synoptic modes/patterns may
develop. The first is the development of a gulf low to replace the
current East Coast low on its way out. This mode is more
conducive to dry air advection and CAD enforcement as the surface
high is unable to shift southward. The other dominate mode relies
on the high over the Northeast sagging southward and reinforcing
the more climatologically dominate summertime feature, the Bermuda
High. This would allow tropical moisture to ascend further
northward and bring wetter conditions across parts of central and
north GA.
SM
&&
.AVIATION...
(00Z TAFS)
Issued at 741 PM EDT Tue May 30 2023
VFR ceilings to start this TAF set but MVFR and IFR ceilings will
move in over night. There are still some isolated showers across
the area but they should stay isolated enough to stay away from
the TAF sites. Will see mostly clear skies through 08z-10z Wed
when the lower ceilings will move in with moist easterly flow.
Will see ceilings in the 1000-2000ft range around daybreak then
they will slowly lift into the VFR range by 17z-19z. Will also see
afternoon CU develop with more isolated SHRA/TSRA Wed
afternoon/evening. Will continue with the Prob30 in the TAFs for
now between 20z-00z as they will still be isolated but will have a
little better chance to actually see some precip at the TAF
sites. Winds will stay out of the east in the 6-12kt range through
the period.
//ATL Confidence...00Z Update...
Confidence high on all elements.
01
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 63 80 63 81 / 20 30 20 10
Atlanta 64 81 65 82 / 10 20 20 20
Blairsville 58 76 57 79 / 10 30 20 30
Cartersville 63 82 63 84 / 10 20 10 20
Columbus 65 84 66 84 / 0 30 30 20
Gainesville 63 78 63 81 / 10 20 10 20
Macon 65 83 65 84 / 10 30 20 10
Rome 63 83 63 84 / 10 20 10 20
Peachtree City 63 81 63 82 / 10 30 20 20
Vidalia 66 83 66 84 / 10 30 20 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...KAL
LONG TERM....SM
AVIATION...01
As mentioned in the previous forecast discussion, this will
result in increased moisture across northern Arizona, with
forecast PWATs between 0.40 and 0.60 inches. Due to the
persistent dry low levels, it is uncertain at this time how much
potential precipitation will fall with shower and storm
formation, but frequent cloud-to-ground lightning and gusty
outflow winds cannot be ruled out.
&&
.AVIATION...For the 06Z TAF Package...VFR conditions will continue
through the 24-hour TAF period. Look for light and variable winds
overnight becoming gusty from the south to southwest at 10-20 kts
gusting to 30 kts after 16Z. A few cloud buildups Wednesday
afternoon will lead to isolated showers and even a stray
thunderstorm east of a KPRC-KGCN line. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...Wednesday and Thursday...Breezy southwest winds
continue Wednesday afternoon with gusts 15-25 mph. Highest gusts can
be expected along and downslope of the high terrain. Gusts will
become westerly and drop to 10-20 mph on Thursday. A slight chance
of showers and isolated thunderstorms both afternoons, favoring the
mountainous terrain. Chances are low-to-none of wetting rain.
Friday through Sunday...Lighter winds with chances of showers and
thunderstorms each day, with afternoon temperatures remaining a few
degrees below seasonal averages.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...Benji/Varian
AVIATION...McCollum
FIRE WEATHER...Varian
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Grand Junction CO
545 PM MDT Tue May 30 2023
.SHORT TERM...(Tonight through Wednesday night)
Issued at 223 PM MDT Tue May 30 2023
Eastern Utah and western Colorado remain under dry and mild
southwesterly flow this afternoon with the usual convective
buildups over the higher terrain and breezy conditions. Midlevel
lapse rates remain in the 9 to 10 deg C/km range with some higher
values of CAPE seen across the northern portions of the CWA and
the spine of the Continental Divide. CAM guidance has been
highlighting some very isolated convection over those same areas
and are performing well as both the HRRR and NAMNEST are nailing
where convection is currently located. The lower levels of the
atmosphere remain very dry so look for another day of gusty
outflow winds from any of this convection. Already seen a few
gusts reaching around 40 mph from what appears to be weak cells so
look for this to continue for the remainder of the day.
The rex block remains across the eastern U.S. this afternoon
while a closed low has come ashore in southern California. Flow
around this low has been responsible for the warm temps and dry
air that has advected into the region. The low will continue to
move eastward overnight and by daybreak Wednesday will be just
about over Las Vegas. As the low continues to move closer to our
CWA, moisture values remain fairly constant though instabiliy does
increase so look for an uptick in convection. CAM guidance is
showing the same with convection moving in a southeast to
northwest trajectory...firing shortly after 12PM continuing
through the early evening hours. Soundings continue to show
inverted V-profiles so, again, look for gusty outflow winds and
some brief, heavy rain.
.LONG TERM...(Thursday through Tuesday)
Issued at 223 PM MDT Tue May 30 2023
The closed low will be just to the southwest of the Four Corners
Thursday morning and will fill through the day as it...very
slowly... moves to the north. Forecast Skew-Ts keep lower levels dry
during this timeframe but midlevels become saturated so any
convection that fires, and it will, will likely bring some gusty
outflow winds. Guidance is suggesting daytime heating and increased
instability and lift from the low will bring widespread showers and
storms initially firing over the higher terrain before moving into
adjacent valleys, especially for the northern valleys where steering
flow winds reach between 15 to 20 mph.
From Friday onwards, a notable PWAT increase occurs as indicated
through GEFS and EPS ensemble guidance. As one would expect, this
increased moisture should cause an uptick in precip coverage which
it does. This deeper moisture is also to remain in place through the
long term period and beyond, which will keep precip chances
elevated from day to day. Flow becomes relatively stagnant through
the weekend onwards as a blocking high sets up over the Great
Lakes and disturbances flow and ebb around the low pressure. The
end result is a rather chaotic period of unsettled weather. The
exact details are still murky but the general gist of showers and
thunderstorms each afternoon and evening remains. Look for the
most widespread precip to occur during the afternoon and early
evening hours during peak heating with a few, very isolated
showers possibly continuing overnight.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 544 PM MDT Tue May 30 2023
Very light returns in the vicinity of KHDN late this afternoon
according to radar imagery. However, suspect this was mainly
virga and therefore unlikely to reach the surface given the dry
sub-cloud layer. Regardless, diurnal cooling was already
resulting in decreased intensity and coverage of moist convection
and that trend will continue through 02Z reducing the threat of
impacts at any TAF site tonight. Mid-level convective clouds will
diminish this evening, though cirrus is likely to continue
streaming northward over the area during the night. The low over
the southern California coast will move slowly inland over the
Desert Southwest in the next 24 hours. Increased lift and
moisture ahead of this system, mainly over the Continental Divide,
will result in increased showers and thunderstorms Wednesday
afternoon. Probability not high enough to mention more than VCTS
at this time for KHDN, KEGE, KASE and KGUC after 18Z/Wed.
Otherwise, expect VFR conditions to persist during the period with
winds again picking up from the southwest Wednesday afternoon.
&&
.HYDROLOGY...
Issued at 223 PM MDT Tue May 30 2023
Overall, most forecast hydrographs follow a either a steady or
slight negative slope through the end of the 10 day outlook. But
first, gages are forecasted rise tonight through Wednesday night, in
response to this unseasonably warm weather. However, by Thursday,
river and runoff guidance indicate a slow down in snow to flow in
response to the approaching low pressure system. As cooler
temperatures infiltrate the area, high elevation lows will
potentially dip back below freezing overnight and limit the volume
of snowmelt. The caveat, though, is that this system is also progged
to carry in an abundance of moisture. Expect afternoon showers and
thunderstorms to become widespread by the end of the week, and the
risk for daily convection sticks around for the foreseeable future.
Direct impacts to streams, creeks, and rivers will be highly
dependent on rainfall rates, storm duration and extent. Quick moving
storms will translate a very different hydrologic outcome compared
to a slow moving and/or training storm(s) over the same basin. Thus,
despite low confidence in which basin is favored, additional spikes
are possible leading into the weekend. Median SWE still exceeds 200
percent of normal for the end of May across the Elkheads, Park, Flat
Tops, Elks, West Elks, Grand Mesa, Unc, La Sals, and much of the
southwest San Juans. So, basically, there`s plenty of snow pack
left to melt out...and the spring runoff season continues.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...TGR
LONG TERM...TGR
AVIATION...NL
HYDROLOGY...ERW
Area Forecast Discussion
National Weather Service Grand Rapids MI
739 PM EDT Tue May 30 2023
LATEST UPDATE...
Aviation
.SHORT TERM...(This evening through Wednesday night)
Issued at 330 PM EDT Tue May 30 2023
Recent GOES water-vapor imagery shows a Rex block persisting over
much of eastern North America. In the low levels, broad
southeasterly flow has facilitated a modest increase in low-level
moisture since this time yesterday, with surface dewpoints across
the forecast area ranging from the mid 40s to mid 50s F. This
boundary-layer moisture is supporting the development of high-based
shallow cumulus across much of the forecast area today, as evident
in visible satellite imagery. CAM guidance (e.g., 12z HREF and
subsequent HRRR runs) suggests that cumulus should deepen
sufficiently for isolated sprinkles/showers later this afternoon and
evening, mainly south/east of Grand Rapids. This limited activity
will wane after sunset as the boundary layer cools/stabilizes.
Somewhat more widespread showers/t-storms are expected on Wed
afternoon/evening, albeit "hit and miss" (scattered / chance PoPs).
Surface dewpoints in the 50s, combined with temps again climbing
into the upper 80s to near 90 F, should yield MLCAPE of generally
500-1500 J/kg across the forecast area, per recent RAP guidance.
While overall convective coverage will be limited by the absence of
large-scale lift, weak low-level convergence along the expected lake-
breeze front may support relatively greater coverage near US-131.
Deep layer (0-6 km) bulk shear will be weak (under 10 kts), limiting
convective organization. However, locally gusty outflow winds are
possible, given appreciable downdraft CAPE accompanying a deep, well-
mixed boundary layer.
.LONG TERM...(Thursday through Tuesday)
Issued at 330 PM EDT Tue May 30 2023
No widespread appreciable rainfall is expected through early next
week and the current abnormally dry conditions will only worsen.
Upper high centered over the ern GrtLks Rgn retrogrades slowly
westward and by early next week will be centered in the vicinity
of srn Manitoba. This occurs as upr troughing digs back into New
England, which eventually sends another back door cold front
through MI around Tuesday of next week.
Until then we remain in an early season heat wave of sorts with
daily highs around 90, although dew points will remain below 60
keeping the heat index close to the actual temperature. Any rainfall
will be isolated at best due to persistence of subsidence and dry
air, and probably limited to the afternoon/early evening lake breeze
boundary (near/west of Hwy 131) or other mesoscale sfc
convergence zones. Fire danger will remain elevated due to lack of
rain, particularly for conifer fuels, but thankfully no periods
of stronger winds are anticipated at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 739 PM EDT Tue May 30 2023
VFR conditions will continue through Wednesday evening. Isolated
showers are possible Wednesday afternoon but these were left out
of the forecast for now as coverage is expected to be sparse.
Southeast winds around 7 knots this evening will go light and
variable tonight. West winds 5 to 10 knots near Lake Michigan as
the lake breeze redevelops on Wednesday.
&&
.MARINE...
Issued at 330 PM EDT Tue May 30 2023
Synoptic light wind regime continues, with a southerly component
generally favored Wed and Thurs. The flow will be light enough to
allow the typical diurnal/afternoon onshore lake breezes near 10
kts to kick in and linger into the early evening hours. The
weekend features light easterly flow for the nighttime and morning
hours, flipping to onshore for the afternoon and early evening
hours.
&&
.CLIMATE...
Issued at 330 PM EDT Tue May 30 2023
Record High Temps
GRR MKG LAN AZO BTL BIV
Tue 5/30 92-2019 90-2018 95-1895 94-1978 94-1895 94-1942
Wed 5/31 95-1934 88-2016 96-1895 93-1911 94-1919 92-1934
Thu 6/1 102-1934 88-2014 97-1934 102-1934 100-1934 100-1934
Record Warm Lows
GRR MKG LAN AZO BTL BIV
Tue 5/30 68-2018 74-2022 70-2022 72-2018 72-2018 70-2018
Wed 5/31 73-1937 70-1970 73-2022 71-2022 71-2022 73-1937
Thu 6/1 74-1934 66-1970 68-1970 71-1895 71-1895 75-1934
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SHORT TERM...Kenyon
LONG TERM...Meade
AVIATION...Ostuno
CLIMATE...NJJ
MARINE...Meade
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
947 PM EDT Tue May 30 2023
.SYNOPSIS...
Weak high pressure remains over the area through Friday as a low
pressure system near the Carolina coast slowly weakens. A weak cold
front drops south across the area Saturday. High pressure returns
for early next week. Another cold front will arrive from the north
toward the middle of next week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 930 PM Tuesday: A Rex block will evolve tonight into tomorrow
as a closed upper low meanders across the northern Gulf of Mexico.
Farther north, a high latitude ridge will amplify across New
England into the Great Lakes region. At the surface, a backdoor
cold front is slowly moving southwest across the area. Lower
ThetaE air will move into the region in its wake, particularly
above the PBL tonight--dewpoints aren`t exactly tumbling behind
it. The convective layer looks so shallow that remaining thunder
probs have now been removed from the fcst. Showers however will
continue to bubble near the boundary tonight. HRRR continues to
depict a rapid increase in coverage in the middle of the night,
perhaps a result of flow turning a bit more southeasterly over the
sfc airmass, but still think overall coverage warrants no better
than isolated to scattered wording. Min temps appear on track but
have touched up hourly trends a bit.
Another low stratus deck still looks to develop with cloudy skies
continuing into much of tomorrow. Isolated showers cannot be ruled
out area wide tomorrow, but the greatest coverage will likely
reside across the southwest mountains where the greater ThetaE
will reside. Cloud cover will also keep high temperatures once
again below normal with highs in the 70s.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 130 PM EDT Tuesday: Surface high pressure centered over
Pennsylvania through this period will keep east to northeast low
level flow across the forecast area. This will be the main mechanism
driving the weather through this timeframe as the mid level pattern
will not feature any strong system near us. The low level flow will
keep some moisture in place but will also keep temperatures normal
to slightly below normal. Robust convection is not expected due to
limited instability but some upslope mainly mountain showers are
possible.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 130 PM EDT Tuesday: The mid level pattern starts to play a
more significant role by this weekend as a fairly deep closed low is
expected to form off the northeast coast. This will drive another
area of surface high pressure down the east side of the
Appalachians, which will reinforce the short range surface pattern
for Sunday into early next week. Ahead of this feature, Saturday
looks to be the warmest day of the period in our area with highs
climbing into the mid 80s (slightly above normal) outside of the
higher elevations. Highs will slip back to slightly below normal
Sunday and Monday.
The probability of precipitation looks limited through the extended
period. There should be some upslope weak convection in the
mountains both Sunday and Monday but otherwise it should be mainly
dry.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: A few SHRA linger invof backdoor cold
front oozing southwestward thru the area, but chance at all the
TAF terminals appears too low to mention. This small chance will
drop a bit by late evening, but the boundary and/or easterly
flow into the mountains could spawn a stray shower even after
midnight. Brief MVFR vsby would be the main threat if one did pass
over a terminal. Remnant stratocu in the 045-100 layer will be
seen this evening. Moist, easterly low-level flow again looks to
produce MVFR to IFR stratus over all terminals prior to dawn. This
deck will slowly mix back up to low VFR by around midday Wed,
with isolated SHRA again in the fcst Wed aftn, not yet warranting
a mention at KCLT.
Outlook: Isolated SHRA/TSRA and associated restrictions appear
possible near the Appalachians Thu and Fri afternoon. Continuing
easterly flow will pose some risk of early morning fog/stratus
Thu and Fri mornings, particularly at KCLT/KHKY. The easterly flow
regime may last into the weekend.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...TW/Wimberley
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service North Platte NE
618 PM CDT Tue May 30 2023
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 216 PM CDT Tue May 30 2023
Key Messages:
- Scattered thunderstorms this evening and tonight, some of which
may be severe with damaging winds and hail being the primary threats,
especially across southwest Nebraska where an Enhanced Risk of
Severe Thunderstorms exists.
- Thunderstorms are possible again on Wednesday evening, however,
the severe threat appears limited to portions of southwest
Nebraska at this time.
- Unsettled weather continues for Thursday into the weekend with daily
chances for thunderstorms with heavy rain being the primary
concern.
- Temperatures remain at or slightly above normal in the 70s and
80s each day through the weekend.
Recent GOES-16 WV and RAP 500-mb analysis showed a compact low
pressure system centered across southern California. Further
northeast of this feature, an upper-level shortwave trough was
apparent across southern Manitoba into north central North
Dakota, extending southeast across the Nebraska/Iowa border. An
upper- level ridge was situated across the Ohio River Valley and a
closed low off the coast of North Carolina. Further southwest of
these features, a near stationary upper-level trough was evident
across the Gulf of Mexico. A weak shortwave disturbance was
lifting northeastward across the Four-Corners region. At the
surface, low pressure was situated across southeastern Colorado
with a dryline extending south across eastern New Mexico. Closer
to home, a weak surface boundary was draped across southwest into
northeastern Nebraska. At 2PM CT, temperatures ranged from 79
degrees at Imperial to 83 degrees at Valentine and O`Neill.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 216 PM CDT Tue May 30 2023
This evening and tonight...Scattered thunderstorms have begun to
develop across eastern portions of the Cheyenne Ridge and Palmer
Divide as of 2 PM CT. As these thunderstorms track eastward into the
Nebraska Panhandle, upscale growth is expected resulting in a MCS
to track west to east across western and north central Nebraska
beginning around 22Z. Surface temperatures in the 80s and dew
points mixing into the upper 50s to lower 60s will support steep
low to mid-level lapse rates approaching 8.5 C/km, further
contributing ample instability (MLCAPE ~2,500 J/kg) across the
area. Recent forecast soundings show an inverted-v profile
suggesting that these thunderstorms will be high-based. The
environment is supportive of severe wind gusts (some gusts may
reach 75 mph or greater) and a few cells may be capable of large
hail. The window of timing of the greatest severe threat is from 6
PM to 12 AM CT across western and north central Nebraska. The
severe threat will diminish across the areas as the system
continues to progress towards eastern Nebraska through 10Z due to
diurnal cooling and a weak-sheared environment.
Wednesday and Wednesday night...The aforementioned upper-level low
across southern California will continue to track eastward,
centering over the Arizona/Nevada border Wednesday evening.
Another shortwave embedded in the flow aloft will propagate
across the area in the evening bringing another round of scattered
showers and thunderstorms to the area Wednesday evening into the
overnight hours. Similar to today, the expectation is that these
thunderstorms will begin to develop off the Front Range and
eastern Cheyenne Ridge late Wednesday afternoon. Model solutions
continue to suggest that this activity will be less organized as
compared to today, however, ample instability and meager shear
across portions of southwest Nebraska will support an environment
capable of strong winds and large hail. Thus, agree with SPC
Outlook of a Marginal Risk of Severe Thunderstorms on Wednesday
for portions of southwest Nebraska.
In addition to the severe risk on Wednesday, the WPC has portions of
the Nebraska Panhandle into southwest Nebraska outlooked for a
Marginal Risk of Excessive Rainfall. PWAT values approach 1" across
southwest Nebraska, some locations may even exceed 1". This combined
with ample CAPE values of 1,000 to 2,000 J/kg will support
convection capable of heavy rain.
.LONG TERM...(Thursday through Tuesday)
Issued at 216 PM CDT Tue May 30 2023
The previously mentioned upper-level low will continue it`s eastward
progression before settling across the Four Corners region with
broad upper-level high pressure centers over the northeastern CONUS.
Multiple shortwaves embedded within the flow aloft will track across
the forecast area bringing a continued unsettled weather pattern
into the weekend. The severe risk appears low during this period
with heavy rain being the primary threat across the area. Southeast
winds will bring an influx of moisture across the area with PWAT
values of 0.75" and potentially exceeding 1" across the area. In
fact, both the NAEFS and ENS ensemble guidance NAEFS and ENS
ensemble guidance highlights this influx of moisture, suggesting
that the mean PWAT will meet or exceed the 90th percentile for
Thursday into the weekend. WPC has portions of the area highlighted
for a Marginal Risk of Excessive Rainfall for Thursday into
Saturday. Given recent heavy rainfall for the last few days across
the area, any storms that produce heavy rainfall could exacerbate
any flooding potential across the area. Will continue to monitor
the heavy rain potential with subsequent forecasts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 618 PM CDT Tue May 30 2023
Thunderstorms are the primary aviation weather concern for
western and north central Nebraska through tonight. Ongoing
scattered thunder in the panhandle will grow in coverage and
intensity as it spreads east through the evening. The greatest
impacts at KLBF and KVTN will occur sometime around 31/03z with
strong winds, torrential rain that will limit visby, and possibly
hail. Thunder coverage should dissipate by 31/06z for most
terminals. Southerly winds ahead of the convection will switch to
west with the storms, then become light overnight. Redevelopment
of storms is possible by mid-late afternoon Wednesday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Snively
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1055 PM CDT Tue May 30 2023
.UPDATED TO INCLUDE 06Z AVIATION DISCUSSION...
Issued at 1055 PM CDT Tue May 30 2023
.DISCUSSION...(This evening through Tuesday)
Issued at 229 PM CDT Tue May 30 2023
Key Messages:
- Isolated to scattered showers and thunderstorms expected later
this afternoon. A few storms could contain large hail and heavy
downpours.
- Garden variety thunderstorm chances every day this week due to hot
and humid conditions. A lack of strong forcing should keep storms
from becoming severe in most cases.
- Speaking of the heat, temperatures in the low 90s likely later in
the week and into the weekend.
Discussion...
The MCV that was the cause of the showers and storms
this morning has moved over the arrowhead in northeastern Minnesota,
with a blossoming cumulus field over much of the MPX CWA this
afternoon. As we get into the late afternoon, it is likely a few of
these cumulus clouds grow to the point we see showers and a few
storms beginning to form, with the peak timing through the mid
evening before activity begins to diminish. Per SPC mesoanalysis, we
have a healthy amount of instability in the 2000-2500 J/KG area which
would support stronger storms, however we have a lack of deep layer
shear for storm maintenance as well as a lack of strong forcing. The
shortwave trough that was supposed to be the focus for our activity
has been pushed northwards along the track of the MCV, which has put
it firmly outside of our coverage area and will likely limit the
spread of storms this afternoon and evening. Given the instability we
do have as well as strong low level lapse rates, scattered garden
variety thunderstorms with isolated stronger cells still remains
possible, with hail remaining the primary threat to consider as far
as severe weather goes. The best opportunity for stronger storms will
be if we can get a few cells forming within a close area, with
boundary interactions between them acting as the forcing for the
strong storms, but this remains a lower likelihood possibility if the
days CAM runs are to be believed with only isolated weaker storms
within the last few HRRR runs as well as limited coverage in the 12z
SPC HREF. As was mentioned in the previous AFD, slow storm motions
could result in locally heavy rain for those fortunate enough to see
storms forming today, with other areas continuing to remain dry.
Heading into the overnight hours, a strengthening low level jet will
keep some activity going over southern Minnesota, likely remaining
mostly a rain and lightning show rather than a legitimate severe
weather threat.
Through the rest of the week, we continue to see a lack of even
moderately strong synoptic scale forcing for ascent to produce
severe storms, with more of this daytime heating forced weaker
activity. Our upper level pattern continues to remain stagnant such
that deep layer shear remains absent, with storm chances remaining
limited to whatever weak shortwave activity we can muster up. These
meager storm chances continue throughout the week as mainly an
afternoon affair, becoming weaker towards the weekend due to a
strengthening upper level ridge, which will also lead to increasing
temperatures. NBM bias correction continues to trend high
temperatures too low, with low to mid 90s possible towards Friday
especially. There are small signs of relief on the horizon with the
ridge weakening by the middle of next week, however there has yet to
be a strong push within any of our longer range deterministic
guidance to truly drop things towards more normal temperatures in
the upper 70s to low 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1055 PM CDT Tue May 30 2023
Storms have come to an end tonight and it should remain quiet through
the morning. Some chances start again the afternoon, with the better
chances coming in the evening. Outside of the thunderstorms chances
it will be VFR through the period. Winds will be light overnight and
then pick up to around 10 knots on Wednesday from a southerly
direction.
KMSP... No additional concerns.
/OUTLOOK FOR KMSP/
THU...VFR. Chc aftn/eve TSRA. Wind S 10-15kts.
FRI...VFR. Chc aftn/eve TSRA. Wind SE 10-15kts.
SAT...VFR. Chc aftn/eve TSRA. Wind SE 10-15kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...TDH
AVIATION...NDC
Area Forecast Discussion
National Weather Service Marquette MI
737 PM EDT Tue May 30 2023
.SHORT TERM...(This afternoon through tonight)
Issued at 241 PM EDT TUE MAY 30 2023
For the majority of the UP, today will be quiet and warm as ridging
centered over the Lower Great Lakes still extends out across the
Upper Peninsula. RAP analysis shows a shortwave over northeast ND
which will track northeast into Manitoba the rest of today and
tonight. An associated sfc low just northeast of the shortwave will
follow a similar northeast path through Manitoba tonight. Ridging
keeps the dry and mostly sunny conditions through the rest of today,
with cloud cover moving into the far west this afternoon in
association with a small shortwave noted by a swirl in vis/radar
imagery over the arrow head of MN and far western Lake Superior.
Only a slight chance of showers is expected around Ironwood late
this afternoon ahead of the frontal boundary currently located in
MN. With CAPE values on most BUFKIT model soundings staying low (100-
200 J/Kg) in Ironwood, I am feeling confident that thunder will stay
out of the forecast until Wed. The southerly winds, stronger in the
west, will aid in bringing warmer temps to the Superior lakeshores
this aftn with highs reaching into the 80s; coolest temps located
along Lake Michigan in mid to upper 70s.
Tonight could see some slight chances for light rain showers along
the far west, but otherwise mostly clear skies and dry weather will
continue for the rest of the UP. Lows should settle into the 50s;
rain showers and cloud cover may keep the far west and Keweenaw in
the low 60s.
.LONG TERM...(Wednesday through Tuesday)
Issued at 431 PM EDT TUE MAY 30 2023
Mid-level ridging will influence the weather pattern throughout the
extended period, resulting in high temperature trends of 15 to 20
degrees above normal across the interior. This puts daytime highs
in the mid to upper 80s and even some low 90s across the interior.
Lakeshores will be cooler as always with highs topping off in the
60s and 70s. These temperatures combined with min RH values in the
mid 20s will elevate the fire threat on Wednesday, but light winds
will help to mitigate the threat somewhat. And, as the
aforementioned ridge drifts eastward late in the week, an uptick in
Gulf moisture will at least push min RH values above the 30 percent
mark from Thursday through Sunday. After that though, the very dry
conditions return for Monday and Tuesday.
Simultaneously, the brief moisture influx will provide just enough
instability to maintain daily thunderstorm chances (mainly west and
central) from Wednesday through Sunday. The best chances will be
in the afternoon and evening hours especially on Thursday and
Friday with a surface boundary in the vicinity, but modest MLCAPEs
in the 500-1000 j/kg range and limited wind shear will prevent
strong to severe convective development. Most activity will likely
be pulse-like in nature.
Further out, a shift in the pattern starting Monday will start a
downward trend in temperatures with daytime highs closer to normal
by Tuesday as a low pressure system drops into the northeast U.S.
Look for highs generally in the 70s across the interior with upper
50s/low 60s along the lakeshores.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 735 PM EDT TUE MAY 30 2023
VFR conditions will prevail at all sites through the entire TAF
period. Some mid-level clouds are beginning to move through IWD with
slight chances for rain showers mainly this evening. However,
with the dry environment working against all developing precip,
confidence remains too low to include any showers in the TAF so
will only have VCSH. CMX and SAW will remain dry, but could also
see some mid level clouds through tonight. Generally southerly
winds are expected through the entire TAF period except for the
easterly winds at CMX this evening and late Wednesday afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 441 PM EDT TUE MAY 30 2023
Winds below 20 kts are expected across the lake for the entire
forecast period with mid-level ridging over the region. There will,
however, be thunderstorm chances across the western portions of the
lake tonight with more widespread chances Wednesday through Friday,
especially during the afternoons and evenings. Since storms will be
diurnally driven and lacking synoptic support, strong to severe
storms are not anticipated at this time.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...TDUD
AVIATION...Voss
MARINE...TDUD
Area Forecast Discussion
National Weather Service Mount Holly NJ
916 PM EDT Tue May 30 2023
.SYNOPSIS...
High pressure remains anchored over the Northeast through mid-week
while weakening low pressure off the coast of the Carolinas
will linger into Thursday. The low will continue to bring some
scattered showers to the Delmarva Peninsula, but dry weather
should prevail overall with increasing temperatures through the
end of the week. A back-door cold front passes through on
Saturday and introduces a cooler airmass for the weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
Forecast on track this evening. Only minor adjustments made to
the grids. Previous full discussion below...
High pressure south of the Canadian Maritimes will sag to the
south and east tonight through Wednesday. Meanwhile, upper low
over the Mid- Atlantic continues to dissipate.
The other aspect to this forecast is smoke and haze from wildfires
in Nova Scotia will spread into the region. More on that in a bit.
In terms of sensible weather, onshore flow will continue tonight
through Wednesday. Another round of light rain showers may
impact southern Delmarva, again with minimal QPF, Wednesday
afternoon.
With onshore flow and increasing low level moisture spreading into
the region, patchy fog and drizzle is likely for coastal areas and
areas just inland from the coast late tonight through Wednesday
morning. In addition, a stratus deck will spread farther inland
to about the I-95 corridor.
Clouds scatter out Wednesday morning, giving way to hazy sunshine in
the afternoon.
Lows tonight will be in the mid and upper 40s to low 50s. Highs on
Wednesday will top off in the upper 70s to low 80s inland, and in
the upper 60s to low 70s along the coast and just inland.
Smoke from wildfires in Nova Scotia will then spread west into the
region from the northeast. Latest HRRR and RAP vertically integrated
smoke forecasts have one wave spreading into the region into this
evening, and then another wave on Wednesday. We currently have a
bit of a haze and the smell of smoke at the WFO, but this may be
related to an ongoing fire on the base. Have included
widespread haze with a smaller area of patchy smoke. HRRR is
also indicating the potential for smoke to mix down to the
surface. Air Quality Alerts have been issued for all of New
Jersey and southeastern PA, including the Philadelphia area. Be
prepared for the smell of smoke in addition to some reduced
visibility.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
A strong upper ridge will remain overhead for the short term period
while upper troughing digs across the Southwest. The flow will be
quite meridional aloft and the resultant blocking pattern will hold
strong through the end of the week. At the surface, high pressure
remains in control while a weak surface low spins off the coast of
the Carolinas.
Weak onshore flow Wednesday night will introduce a marine layer
with low stratus/fog/light drizzle as moisture is trapped
underneath a subsidence inversion around 900 mb. Further inland
(Lehigh Valley to the Poconos) expect mostly clear skies and,
with wind going light to calm, efficient radiational cooling,
though warm advection will work to offset the cooling and lows
will be a few degrees warmer than Wednesday night in the low
50s. In addition, expect that some haze/smoke will still be
around into the early overnight, so maintained the patchy smoke
mention.
Temperatures will rebound quite quickly on Friday as the NBM is
still holding firm with highs in the upper 80s and low 90s, while
cooler along the coast. Latest guidance has continued the slight
increase of 850 mb temperatures to around 17-19C which is very close
to supporting highs in the 90s. NBM prob MaxTs are indicating a >60%
chance of MaxTs >90F primarily along I-95 and west, though MOS
guidance is still not budging from the upper 80s. Regardless, we`ll
be seeing above average temperatures across the board. Forecast
soundings show a very deep, dry boundary layer, so do expect that
dew points will mix out in the afternoon and apparent
temperatures should remain around actual air temperatures. A
sea breeze should develop in the afternoon and will drop
temperatures some as it progresses inland.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The forecast still remains more uncertain going into the weekend.
The deterministic suite of guidance indicates a potent shortwave
diving south out of New England and a back door surface front coming
onshore on Saturday. Meanwhile, an area of surface low pressure will
be sliding up the Atlantic coast, and both the GFS and ECMWF show
the shortwave aiding in the low`s development before quickly
evolving into a closed low itself.
Both deterministic and ensemble guidance remains spread on the
timing of the backdoor front as well as the strength and track
of the surface low. The GFS and Canadian favor a very early
Saturday morning passage with the ECMWF later. Ultimately, the
setup is favoring a post-frontal cooldown on Saturday after a
quite warm Friday with thickness values falling and cold
advection with northeasterly onshore flow. Held with NBM which
introduces some PoPs (20-40%) with frontal passage on Saturday,
though moisture may be overall lacking with the front. Cool high
pressure is expected to build in on Sunday with mostly dry
conditions and high temperatures in the low to mid 70s.
The beginning of next week looks to stay dry overall for now, but
there is quite a bit of model spread regarding where this closed
coastal low will end up. Current ensembles keep it a good distance
offshore and mostly unimpactful to our area, though a surface
boundary may sag south across the area sometime Monday. Run-to-
run fluctuations continue essentially after the frontal passage
Saturday, so stuck close to the consensus/NBM forecast here
until we can narrow down possibilities over the next several
days.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight (00Z through 12Z)...VFR initially, then MVFR CIGs likely to
develop at KTTN/KPNE/KPHL/KILG and IFR CIGs with MVFR VSBYs in fog,
stratus, and drizzle will develop at KMIV/KACY after 09Z. Some
haze from wildfire smoke is possible prior to the arrival of
fog/stratus. E winds around 5-10 kt. Moderate confidence.
Wednesday (12Z through 00Z)...Any sub-VFR conditions will give way
to VFR. Latest HRRR/RAP guidance has haze/smoke clearing out of
the I-95 terminals by the early afternoon, though hanging around
the Lehigh Valley terminals through the day. Cannot rule out
VSBY restrictions in smoke, but probabilities are low. E-NE
winds 5 to 10 kt, increasing to around 10 kt in the afternoon.
Moderate confidence.
Outlook...
Wednesday night...Sub-VFR conditions expected with low stratus and
fog, especially at I-95 terminals and KACY/KMIV. Some haze and
patchy smoke at mid-levels through the early overnight. Variable
wind less than 5 knots. Moderate confidence.
Thursday...Some early morning fog/low stratus may continue sub-VFR
conditions early, otherwise expect VFR for the remainder of the day.
Northeasterly wind 5-10 knots becoming southeasterly in the
afternoon. Moderate confidence.
Friday...VFR. Northeasterly wind 5-10 knots. Moderate confidence.
Saturday...Sub-VFR conditions possible with passage of a cold front.
Northeasterly wind increasing to 10-15 knots with gusts to 25 knots
behind the front. Low confidence.
Sunday...VFR. Northeasterly wind 5-15 knots. Low confidence.
&&
.MARINE...
NE winds continue to diminish this evening, and will eventually
settle to around 10 to 15 kt after midnight. On Wednesday,
winds will be NE 10 to 15 kt with gusts up to 20 kt. Seas of 5
to 7 feet will subside to 3 to 5 feet tonight through Wednesday.
Small Craft Advisory has been allowed to expire for the lower DE
Bay, and sub-SCA conditions are expected for DE Bay through
Wednesday. Seas remain elevated on northern NJ ocean waters
through tonight, then seas will be below 5 feet through
Wednesday. For southern NJ and DE ocean waters, seas remain
around 5 feet through Wednesday, and SCA remains in effect
through Wednesday.
Outlook...
Thursday...No marine headlines expected. Northeasterly wind 5-10
knots. Seas 3-4 feet.
Friday...No marine headlines expected. Southeasterly wind 5-10
knots. Seas 2-3 feet.
Saturday...Small Craft Advisory conditions possible. Northeasterly
wind 5-10 knots in the morning increasing to 15-20 knots with gusts
to 25-30 knots in the afternoon. Seas 2-3 feet building to 5-7 feet
from north to south.
Sunday...Small Craft Advisory conditions possible. Northeasterly
wind 15-20 knots with gusts to 25 knots and seas 5-7 feet in the
morning. Conditions may improve later in the day.
&&
RIP CURRENTS...
For the beaches of Atlantic County and Cape May County in New
Jersey, and for the beaches of Sussex County in Delaware, there is a
HIGH risk for the development of dangerous rip currents into
Wednesday evening. We are anticipating a northeast wind 10 to 15 MPH
with breaking waves of 3 to 4 feet.
For the beaches of Ocean County and Monmouth County in New Jersey,
we are expecting a northeast to east wind 5 to 10 MPH on Wednesday
with breaking waves of 2 to 3 feet. The conditions should result in
a MODERATE risk of rip current in those areas.
Wind speeds and breaking waves are forecast to diminish slightly for
Thursday. An east to northeast wind 5 to 10 MPH is expected with
breaking waves of 2 to 3 feet. The rip current risk should be
MODERATE for all the Delaware and New Jersey beaches at that time.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...High Rip Current Risk through Wednesday evening for NJZ024-025.
DE...High Rip Current Risk through Wednesday evening for DEZ004.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ450-451.
Small Craft Advisory until 8 PM EDT Wednesday for ANZ452>455.
&&
$$
SYNOPSIS...Brudy
NEAR TERM...Hoeflich/MPS
SHORT TERM...Brudy
LONG TERM...Brudy
AVIATION...Brudy/Hoeflich/MPS
MARINE...Brudy/Hoeflich/Iovino/MPS
Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Tue May 30 2023
.Update...Updated Aviation
&&
.SYNOPSIS...
Mainly below normal temperatures will persist across the
region through the end of the week. A weather disturbance moving
across the Desert Southwest during the next couple of days will
deliver breezy to locally windy conditions, with the strongest winds
expected across portions of Imperial County. A warming trend is
anticipated by the weekend with temperatures returning back to
around normal. No precipitation is expected through at least the
next 7 days.
&&
.DISCUSSION...
Latest water vapor imagery reveals a closed upper low drifting
eastward into southern California. Across much of Arizona,
temperatures are running close to what they were this time
yesterday, but further west and closer to the low across
southeastern California, conditions are considerably cooler. High
temperatures so far today have only reached the mid 80s across the
Imperial Valley, however this is still several degrees higher
than the record low maxes for the date. Otherwise, the main
weather story today will be the widespread afternoon and evening
breeziness. Latest HREF continues to indicate a 30-60 percent
chance of peak gusts reaching 25 mph in the Phoenix area this
evening. Further west across the Imperial Valley, latest trends in
the HRRR suggest peak gusts will reach 40-45 mph this evening and
a Wind Advisory continues for these areas.
With the low expected move into northern Arizona during the day
on Wednesday, another round of breezy to locally windy conditions
is expected once again during the afternoon/evening hours with
Imperial County once again seeing the strongest winds with gusts
in excess of 30-35 mph while elsewhere gusts will generally range
between 20-30 mph. With heights aloft lowering in response to the
upper-level low, a cooldown is expected across many areas. In
fact, there is a greater than 60% probability according to the
latest NBM guidance that temperatures across many of the western
desert areas of southwest Arizona and southeast California fail to
reach 90 degrees, with highs remaining stuck in the upper 80s.
Across the south-central Arizona lower deserts, including the
Phoenix area, those probabilities of failing to reach 90 degrees
are a bit lower at between 20-40%. Nevertheless these temperatures
will be a good 8-10 degrees below normal for this time of the
year.
The negative height anomalies will persist through Thursday and
Friday so temperatures will continue to remain below normal with
highs in the lower to middle 90s. By the weekend, as heights aloft
rise in response to weak high pressure building in, a warming
trend is anticipated with temperatures returning back to near
normal with highs in the low 100s. By early next week, model
guidance is indicating yet another upper-level low moving from
the eastern Pacific and through the Desert Southwest. This low
pressure may bring just enough moisture to result some showers
mainly across eastern and northern Arizona, where slight chances
(20-30% PoPs) exist according to the NBM. Otherwise, with heights
aloft lowering, slightly cooler temperatures are anticipated.
&&
.AVIATION...Updated at 2320Z.
South-Central Arizona including KPHX, KIWA, KSDL, KDVT:
Breezy conditions this evening will be the main aviation during
the TAF period. Winds will emanate out of the W/SW for the
remainder of the afternoon and evening, with gusts primarily 20-25
kts. Due to this enhanced flow, our typical shift to the E is
expected to occur later than usual. Current model guidance is not
in full agreement about when this shift will take place, but
10-11Z looks like the most likely timeframe as of now. Besides a
FEW high level clouds around 20 kt tonight, skies will be mostly
clear through tomorrow morning.
Southeast California/Southwest Arizona including KIPL and KBLH:
Breezy to windy conditions will be the main aviation concern
during the forecast period. IPL will see W winds pick up over the
next several hours, with peak gusts upwards of 35 kts later this
evening. These strong winds have the potential to generate areas
of blowing dust, which could lead to reductions in visibility at
times. Winds out the S/SW at BLH are not expected to be as strong,
but peak gusts of 25 kts are likely this evening. Winds are
expected to diminish at both terminals overnight. Clear skies are
anticipated through the period.
&&
.FIRE WEATHER...
Seasonably dry conditions are expected to prevail through the
period along with daily afternoon/evening breezes. Enhanced winds
are anticipated today and Wednesday as a weather disturbance
moves across the Desert Southwest with afternoon/evening gusts
ranging between 20-30 mph across most areas, with the western half
of Imperial County likely to observe stronger gusts in excess of
40 mph later today and slightly lower speeds on Wednesday. MinRH
values are expected to range between 8-15% today and increase to
between 10-20% on Wednesday. The combination of the enhanced
winds as well as the low RH values will result in an elevated fire
danger threat.
Below normal temperatures are anticipated beginning on Wednesday
and continuing through the end of the week with MinRH values
generally ranging between 10-20%. Thereafter, a warming trend as
well as slightly drier conditions are anticipated next weekend.
Winds will be weaker during the second half of the week through
next weekend, although the typical diurnal breezes will persist.
&&
.HYDROLOGY...Updated 200 AM MST 5/30/2023
GILA: Ongoing releases from Painted Rock Dam have decreased to
the point that now the downstream gauges along the Gila River near
Dateland as well as near Dome/Yuma have fallen 1.5-2 feet below
action stage. Despite the declines, will maintain the current
Flood Warnings downstream from Painted Rock Dam until improvement
of impacts can be confirmed with officials. The Flood Warnings
remain in effect through this evening.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 8 AM PDT Wednesday for CAZ562-566.
Wind Advisory until 4 AM PDT Wednesday for CAZ563-567.
&&
$$
DISCUSSION...Hirsch/Lojero
AVIATION...RW
FIRE WEATHER...Lojero
HYDROLOGY...Lojero/Benedict
Area Forecast Discussion
National Weather Service Pueblo CO
846 PM MDT Tue May 30 2023
.UPDATE...
Issued at 824 PM MDT Tue May 30 2023
Line of thunderstorms has pushed eastward into Kansas with the
severe risk ending across the southeast CO counties. Have
cancelled the Severe thunderstorm Watch for the rest of this
evening. Will still be watching the progression of any westward
propagating outflows and higher dew point return from convection
to our east. NamNest and HRRR still indicates the potential for
more thunderstorms to develop across southern sections of the
southeast plains around midnight as a south to southeasterly low
level jet increases. Will carry some pops past midnight across
southern sections of the area and watch how this evolves.
If thunderstorms develop, they should be more elevated and carry
less of a severe risk, though some small hail seems plausible with
the stronger storms as mid level lapse rates steepen after
midnight. -KT
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 340 PM MDT Tue May 30 2023
Key Messages:
1) A few strong to severe storms are likely over the far eastern
plains the rest of this afternoon and early evening with very strong
winds the primary threat.
2) Scattered strong to severe storms will be likely tomorrow
afternoon over all of the plains, with all severe modes possible.
Heavy rains also likely over plains.
3) Locally heavy rains possible in the mtns tomorrow raising the
risk for burn scar flooding.
Currently...
High based shower activity was noted over the mtns and San Luis
Valley at 2 pm. In addition, thunderstorms were developing along the
I-25 corridor region, with the strongest storms down along the
southern I-25 corridor region.
Convective scale parameters were indicating CAPE was rather
significant over the plains, with sfc based CAPE well over 3000 over
the far eastern plains. Deep shear was quite weak to non-existent
(not registering on the SPC meso page). T/Td spreads over the eastern
plains were showing depressions of about 30 degrees.
Rest of Today into Tonight
Main concern in the immediate short term is the potential for severe
thunderstorms capable of producing very strong wind gusts to develop
over the plains as the convection over the general I-25 region push
east into the deeper moisture. Given the shear is pretty much
nonexistent, storms should quickly develop upscale and develop
strong outflows as the rapidly intensify and push east. Given the
high CAPE values, intense convective winds will be likely given the
high Dcape values. At this time it appears the strongest convection
should be out of the region around 8 pm
One concern for later tonight will be how much low clouds push back
into the state of CO due to the convection? Models show that the far
eastern counties will see low cigs, but the remainder of the plains
will remain relatively clear.
All guidance later tonight keep winds at a brisk southerly
component, and this will likely continue to bring up low level
moisture to the region which will set the stage for tomorrows
weather.
Tomorrow...
Thunderstorms are likely during the afternoon and there is a good
chance that they will be strong to severe. A potent disturbance over
the southwest US will continue to push towards the region. This
system will advect low level moisture into the region, and this
combined with sufficient solar radiation and cool temps aloft will
allow for some hefty CAPE to develop over the entire area by
tomorrow afternoon. Unlike today where deep shear is very weak, the
shear will be modest by tomorrow afternoon, and this along with the
CAPE, and the upward vertical motion supported by the approaching
Pacific system, will allow strong to severe thunderstorms to
develop. At this time the greatest threat will be large hail and
winds, but there will be a tornado threat also, and this tornado
threat may be enhanced on how outflow boundaries from todays
convection affect the region tomorrow.
CAPE values tomorrow will be rather high over the region, with
values likely in the 2000 to 3000 range by afternoon. This CAPE will
allow for quite a bit of severe convection, so I anticipate a very
busy day in the office tomorrow. Watch boxes will more than likely
be issued for the region.
With increasing moisture in the mountains, thunderstorms will be
scattered, and they will likely be capable of locally heavy rain, so
flash flooding of burn scars may be enhanced tomorrow. In addition,
storms will likely not be moving all that quickly, so this will
increase the potential for flooding over the burn scars. /Hodanish
.LONG TERM...(Wednesday night through Tuesday)
Issued at 340 PM MDT Tue May 30 2023
Key Messages:
1) Increasing chances of precipitation from west to east on Thursday
with potential for stronger storms over the far southeast Plains.
2) Cooler and unsettled weather pattern developing Friday and
persisting into early next week.
3) Locally heavy rainfall and flash flooding potential increasing
through the weekend.
Wednesday night-Thursday night...Modest south to southwest flow
aloft remains progged across the region as a compact upper low
across the Southern Great Basin slowly weakens as it lifts north and
east into the Four Corners region Thursday evening. Ongoing strong
to severe storms across the southeast Plains Wednesday afternoon
move into western Kansas through the evening, with the potential for
scattered showers and isolated thunderstorms continuing over and
near the higher terrain through the late evening and overnight
hours, within weak diffluent flow aloft. Increasing mid level
moisture and uvv ahead of the Four Corners system will allow for
increasing chances of shower and thunderstorm develop over and near
the higher terrain Thursday afternoon and evening. There will be
the potential for stronger to severe storms across the far southeast
Plains, where enhanced southeast low level flow will keep enough
moisture and shear in place. Temperatures on Thursday look to be
near seasonal to slightly below seasonal norms.
Friday-Sunday...Weak upper low continues to slowly drift north and
east across south central and into southeastern Colorado through the
day Saturday and into the Southern High Plains on Sunday. This leads
to a weak but generally deep easterly flow pattern across the region
which will keep daily chances of showers and storms across the area.
With models indicating increasing available moisture with PWATS
approaching 150-200 percent of normal, there will be the potential
for locally heavy rainfall, as well as increasing chances of flash
flooding, especially over and near the higher terrain, where weak
easterly upslope flow will lead storm training. With the cool upper
level pattern, there could also be some light to moderate snow
accumulations across the higher peaks through the weekend, with
temperatures expected to be some 5-15 degrees below early June
norms.
Monday-Tuesday...A messy and weak flow pattern remains in the offing
into next week, with weak upper ridging being indicated across the
Rockies. With moisture expected to remain in place, there will
continue to be daily chances of showers and storms, with the
greatest coverage over and near the higher terrain, along with
temperatures remain generally below seasonal levels.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 340 PM MDT Tue May 30 2023
Isolated high based thundershowers will be possible at KCOS and KPUB
late this afternoon and early evening, but overall I anticipate VFR
conditions. For tonight, guidance keeps skies VFR through tomorrow
morning, however I am a bit concerned that moist outflow from storms
well east of KCOS and KPUB may push back towards the mtns affecting
the two taf sites. For now I plan to keep VFR tonight, but we may
need to adjust this if the outflow materializes.
For tomorrow, thunderstorms are expected at all 3 taf sites during
the afternoon time period as low level moisture will increase and a
disturbance moves towards the region.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KT
SHORT TERM...HODANISH
LONG TERM...MW
AVIATION...HODANISH