Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/30/24
Area Forecast Discussion
National Weather Service La Crosse WI
701 PM CDT Mon Apr 29 2024
.KEY MESSAGES...
- Round of showers and thunderstorms expected going into Tuesday
evening, with a higher risk of severe weather just west of area.
- More showers and storms expected Wednesday night into Thursday.
Likelihood is high /70-90%/ for pockets of heavy rain with
chance for a few stronger storms at times.
&&
.DISCUSSION...
Issued at 200 PM CDT Mon Apr 29 2024
Tonight:
If you include the current, passing trough, there are no less than 6
systems to impact region over the next 10 days...so yes...active
pattern continues.
Current upper low, with large area of wrap around stratus, continues
to make good progress northeastward. Precipitation associated with
this will remain very light with trend towards cloud cover clearing
going into early Tuesday from south to north. Although winds will
diminish overnight as well, temperatures should remain warm enough
to prevent any widespread frost or freeze outside of favored
Wisconsin bogs.
Tuesday and Tuesday Night:
Attention quickly turns to next mid level wave which will move out
of the northern Rockies into the northern Plains on Tuesday. Bulk of
day will be quiet for us in between systems but will have to watch
convective risk with some moisture return ahead of this wave and
stronger mid level flow suggesting some shear to work with.
Question for us centers on how far east this modest instability will
translate and if stronger/severe storms to the west can keep their
strength east of Interstate 35. At first glance it almost appears
any instability gets pinched out to the south as wave moves through,
but trends in the RAP outcomes suggest there still could be enough,
mainly elevated, instability and 0-3km shear to sustain a small risk
/10-20%/ for a severe storm or two. Seems like any threat would be
in our far west with storms weakening and/or losing their
organization as they move east. Examining soundings, hail and gusty
winds would be our threats IF any severe storms work into the west
during the 6-9pm TUE time frame.
Wednesday Night into Thursday:
One could say rinse and repeat with next approaching wave late
Wednesday into Thursday, but there are subtle differences. Larger
trough digs through central Rockies and as it ejects into the
Plains, better /deeper/ poleward moisture transport expected.
Convection will likely be ongoing at start of day Thursday and as
trough ejects into the upper Mississippi River valley could see a
ramp up in storm strength as the day goes on. While bouts of heavy
rain seem likely /70%/ given deeper moisture and high precipitable
water, details on severe weather risk are unclear given how storms
could be impacting setup through a big part of the day. Instability
could be limiting factor once again. This will be another period
worth keeping an eye on as details get worked out.
Although still several days out, looks like front would clear the
area on Friday with another in-between day and seasonal
temperatures. Yet another wave could bring showers back into the
picture on Saturday but by then, low level moisture will be lower
keeping any storm threat a bay.
If you are counting, we still have more systems to track the
following week, but one week at a time.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 645 PM CDT Mon Apr 29 2024
MVFR/VFR ceilings fl020-035 across the region with a little
light rain in the area this evening. Look for improvement in the
ceilings later tonight tonight VFR, then clearing Tuesday
morning. Clouds will thicken during the afternoon with showers
and thunderstorms developing. Unsure how far east the elevated
showers will make it; could be some at RST by 21 or 22Z with
increasing storm chances 23Z and thereafter. West winds diminish
and become southwest and south with time. Southeast wind
increase at RST Tuesday afternoon 10 to 18kts with gusts 20 to
30 kts.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Shea
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Bismarck ND
944 PM CDT Mon Apr 29 2024
.KEY MESSAGES...
- Widespread rain showers are expected to move across the state
from west to east late tonight through Tuesday.
- Windy in southwest North Dakota on Tuesday, with critical fire
weather conditions possible in the afternoon and early
evening.
- Daily chances (low to medium) for rain through the rest of the
week, with temperatures slightly below normal.
&&
.UPDATE...
Issued at 941 PM CDT Mon Apr 29 2024
Main change with this update was just freshening up the cloud
coverage, as some mid level clouds have been entering the area
from the south. A small area of radar returns continue to show
up across the far north, however we haven`t seen any observed
precipitation with these echoes. Apart from cloud coverage,
we`ve just blended the current observations into the forecast.
UPDATE
Issued at 638 PM CDT Mon Apr 29 2024
Not much was needed to be changed with this update. We boosted
PoPs in the northwest and southwest corners of the state due to
some radar returns associated with some more prominent cumulus
growth, but have those PoPs decreasing within the next hour or
so. Otherwise, the forecast largely remains on track.
&&
.DISCUSSION...
Issued at 302 PM CDT Mon Apr 29 2024
A closed upper low is spinning northeastward over northern Minnesota
this afternoon. At the surface, a meridional ridging axis cuts
through the central Dakotas. The ridge axis roughly marks the
delineation of the widespread stratus associated with the downstream
cyclone. The lower cloud deck should slowly erode from west to east
this afternoon, clearing past the Highway 83 corridor but not
reaching the Highway 281 corridor. Meanwhile, a sunny sky will
prevail across western North Dakota this afternoon, aside from some
passing altocumulus clouds over the far west. Highs in the west
should easily reach the lower to mid 60s this afternoon, but could
be limited to the lower and mid 40s underneath the clouds from the
Turtle Mountains through the James River Valley.
A potent shortwave will eject from the base of a Pacific Northwest
trough this evening and quickly pivot into the Northern High Plains
by Tuesday morning. Global and high-resolution ensembles are in good
agreement that a band of widespread rain showers will move across
the state from west to east late tonight through Tuesday afternoon.
There is some minor timing uncertainty, with the HRRR and RAP
consistently showing a quicker progression. Mean ensemble QPF is
advertising around two to four tenths of an inch of rain across
northern and eastern North Dakota, decreasing to only trace amounts
in the southwest.
Highs on Tuesday will mainly be in the 50s, but could be slightly
cooler to the north and east should rain and clouds persist longer
through the day. Winds with the push of colder air on Tuesday are
now looking less impressive than previous forecasts, evident in
deterministic BL analysis, the NBM, and the ECMWF EFI. Temporally
speaking, the strongest winds aloft and greatest momentum transfer
are now favored earlier in the day over southwest North Dakota. This
forecast trend lowers confidence in both meeting advisory criteria
wind speeds and gusts and critical fire weather conditions (see Fire
Discussion below).
An overall active pattern is expected to persist through the rest of
the week, including the upcoming weekend. The first half of
Wednesday should remain dry preceding a transition to southwest flow
aloft, except perhaps along the Canadian border. Shortwave energy in
the southwest flow will then increase rain chances by Wednesday
evening, followed by a deeper trough digging into the Northern
Plains on Thursday. Wednesday is now looking like the warmest day of
the week for the eastern half of the state with highs in the lower
to mid 60s. The digging trough is then forecast to bring
temperatures below normal for Thursday and Friday, with highs only
in the mid 40s to mid 50s. Lows over this time period will mainly be
in the 30s. It is possible that snow could mix with rain wherever
precipitation occurs during the late night and early morning hours
late this week, but no impacts are expected. A warm up finally
appears to be in the cards early next week as ensembles show
positive temperature anomalies, with a jump in the NBM high
temperature distribution on Sunday. The NBM maintains low PoPs over
this time period, and with the warmer air, chances for thunderstorms
could eventually be introduced to the forecast. In fact, machine
learning guidance does imply a low potential for stronger convection
next week Monday when ensemble mean height fields hint at a stronger
wave, though it should be noted there is considerable ensemble
spread at this time range
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 638 PM CDT Mon Apr 29 2024
MVFR ceilings across the James River Valley are expected to slowly
move east through the evening and overnight hours, with VFR
conditions expected elsewhere. Later tonight and through Tuesday, a
low pressure system will bring about MVFR ceilings across the area
from west to east, along with light rain showers across all
terminals. Winds will generally be out of the southeast around 10 to
15 kts for most areas tonight, before a cold frontal passage Tuesday
morning will shift winds to be more out of the south southeast at 15
to 25 kts, possibly gusting to 30 kts at times.
&&
.FIRE WEATHER...
Issued at 302 PM CDT Mon Apr 29 2024
A cold front is forecast to enter southwest North Dakota Tuesday
morning, with winds quickly switching to the west-northwest and
increasing to 25 mph with gusts to around 40 mph. Winds will remain
strong through the afternoon, with perhaps just a slight uptick in
both sustained speeds and gusts. A very dry air mass being advected
in behind the front will lower dewpoints into the teens in southwest
North Dakota by late Tuesday afternoon. The minimum relative
humidity forecast for Tuesday has mostly remain unchanged, with
values as low as 18 percent in the southwest corner of the state and
less than 30 percent for all of southwest North Dakota. However,
there has been a decreasing trend in the magnitude of the wind
forecast over time, as well as the spatial extent of stronger west-
northwest winds. There is also potential for a wetting rain Tuesday
morning, though probabilities are lowest over southwest North Dakota
compared to other parts of the state. Taking all this into
consideration, we have decided to maintain the Fire Weather Watch
for this forecast package.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for NDZ031>033-040>045.
&&
$$
UPDATE...Besson
DISCUSSION...Hollan
AVIATION...Besson
FIRE WEATHER...Hollan
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
625 PM CDT Mon Apr 29 2024
.KEY MESSAGES...
- Quiet Weather Today
- Rain Showers and Thunderstorms Late Tuesday Night
- More Showers and Thunderstorms Possible Wednesday and Thursday
&&
.DISCUSSION...
Issued at 425 PM CDT Mon Apr 29 2024
Surface cyclone and associated cold front has passed through the
area. A secondary mid-level trough axis is still moving across the
area but the cold front has kept most of the moisture away from the
area and overall forcing has been weak. A low-amplitude mid-level
ridge is working across the Northern High Plains, and the subsidence
ahead of this has promoted the development of a surface anticyclone
that been building across the Central Plains into the lower Missouri
River Valley. This is starting to slide underneath the secondary
trough axis and has helped to keep skies mostly clear this
afternoon. Over the Pacific Northwest a PV anomaly will support a
closed-low system but is currently progged to eject multiple vort
maxes over the next few days.
Tuesday, the first H5 vort max breaks away from the Pacific
Northwest Region and pushes the mid-level ridge axis across the
region as well as the center of the surface cyclone. Stronger
vorticity advection occurs across the Front Range and High Plains
that will promote surface cyclogenesis early Tuesday afternoon,
which will promote southerly flow at the surface into our region and
provide WAA. Currently expecting this to push temperatures up into
the lower 80s across most of the forecast area Tuesday afternoon,
and this is also representative of the inner-quartile spread amongst
NBM Members. WAA continues into the early evening hours, while a
cold front develops and propagates across the Central Plains toward
our forecast area. H5 height falls pick up in pace Tuesday evening
as the front approaches the area, increasing convergence and
enhancing overall kinematic support. MLCAPE values ahead of the
front and first H5 trough axis will be around 2000 J/kg per 12z HREF
guidance. 0-6km bulk shear along the boundary will be around 40 kts,
and currently the vector is oriented perpendicular to the boundary.
This shear environment would favor the development of a few discrete
supercells in the evening across our area mainly west of Hwy. 65.
Mid-level lapse rates will be around 7.7 to 8.0 C/km ahead of the
front which will support stronger updrafts. These updrafts in
discrete storms, especially if a supercellular mode is realized,
will present hail threat to around golf balls. However, low-level
storm-relative flow may be stronger with limited CAPE available in
the hail growth zone, which could limit hail sizes. Eventual upscale
development as the low-level jet ramps will also diminish the hail
threat once storms are no longer discrete. Depending on how robust
boundary layer mixing is throughout Tuesday afternoon, steeper
boundary layer lapse rates may support stronger cold pools initially
resulting in damaging wind gusts with stronger storms. The low-level
hodographs per RAP model soundings demonstrate a large amount of
curvature, and progged SRH values in the 0-1km layer between 150-200
m^2/s^2. Both mean wind moving storms and right moving storms could
potentially realize stronger streamwise vorticity ingest, coupled
with stronger low-level storm-relative flow that could support a few
tornadoes with supercells. However, if supercells move too far off
the boundary and get into a weak low-level shear zone, this threat
will quickly diminish and seems likely a scenario for our area.
Therefore, primarily concerned with severe hail and damaging wind
gusts with storms on Tuesday evening. The CAMs this morning and
afternoon have been favoring convection initiation between 23z and
00z from northeastern KS into southeastern Nebraska and far
northwest Missouri. These storms then move toward the southeast.
This timing seems reasonable, as the boundary layer will need a
decent amount of time to destabilize. The main uncertainty with
timing and storm propagation is when the cold front stalls over the
area after the first short-wave trough exits and a compact mid-level
ridge and H5 height rises return Wednesday Morning. There is also a
question as to how strong subsidence will be and what this will do
to precipitation Wednesday morning. This could completely clear
conditions up, but isentropic ascent across the warm-sector may
promote further shower development. CAM solutions are spread out
with how storms congeal overnight into Wednesday morning, and how
long it lasts. With respect to rainfall amounts, will be watching
closely given the flooding conditions present across much of the
area over the weekend. Current deterministic GFS/ECMWF solutions
have about 0.25 to 0.50 inches of QPF primarily north of Interstate
70, with lower amounts southward. Ensemble probabilities for at
least 0.10 inches across northern and central Missouri are around 50-
60 percent Tuesday Night into Wednesday Morning, with probabilities
for exceeding 0.50 inches less than 10 percent. Flash Flood Guidance
currently indicates one hour rainfall totals of 1.10 inches would
needed to promote flash flooding. For now, have not issued any flood
watch products related flash flood potential, as it would
likely be isolated and limited in area with a few stronger
thunderstorms. However creeks, streams, and rivers that are
already experiencing elevated flows may have their flooding
further augmented.
Wednesday, brief period of H5 height rises keeps the thermal
boundary stalled somewhere in the northern two-thirds of the
forecast area, and it is possible additional development if we see
isentropic ascent across the warm-sector Wednesday afternoon.
Perhaps more development could occur if Tuesday Night`s activity
produces a stronger outflow boundary. Current 18z CAMs show a storm
mode more consistent with WAA precipitation then truly surface based
convective parcels. Model soundings Wednesday afternoon indicate a
stronger inversion across much of the area with weaker low-level
lapse rates, as well as weaker shear as the first vorticity max and
short-wave exits the region. Therefore, environment Wednesday
afternoon is not looking favorable for organized activity, but will
need to mindful of elevated convection as mid-level lapse rates
could still be around 8.0 C/km. H5 height falls continue from the
Intermountain West into the Front Range Wednesday prompting another
round of surface cyclogenesis. Response ahead of this will promote
southerly flow and theta-e advection through Wednesday Night, which
if there is enough moisture could continue to promote WAA zone
precipitation ahead of the stalled boundary. Ensemble probabilities
for measurable precipitation into Wednesday afternoon around 40-50
percent.
Late Wednesday Night into Thursday, a stronger short-wave trough and
vort max is progged to break eastward. This will allow stronger dCVA
to deepen surface cyclone across the High Plains and Central Plains
and pushes the thermal boundary across the area. Additional showers
and thunderstorms should develop ahead of this resulting in heavier
rainfall. Ensemble probabilities heading into Thursday begin to push
above 70 percent for measurable precipitation, and 50-60 percent
probabilities for exceeding 0.50 inches of QPF. Storm mode could be
convective if there is enough destabilization of the boundary layer
ahead of the front before it begins to propagate. With these heavier
QPF amounts, concerns for Flash Flooding will increase as rainfall
rates of 1 inch in three hours will still likely be enough to
produce flash flooding. There is still a high degree of uncertainty
with how the storm mode will evolve on Thursday, and how progressive
the system as a whole will be. For now, will not issue any Flood
Watch headlines until the forecast becomes more uncertain, but
currently the soils are not in the best shape to handle as much
water that this could produce. As of any severe threat Thursday,
this will largely depend on if there is enough instability for a
convective storm mode.
In the extended forecast, there is a lot of spread in the exact
timing of trough axes across the Central CONUS but more rounds of
rain showers and thunderstorms are likely. Ensemble probabilities
are favoring additional QPF Saturday into Sunday, and then again
Monday Night into Tuesday. The timing of this may change as we
likely will be tracking a few closed-low system across portions of
Canada. It appears that high temperatures will generally be in the
mid 70s to lower 80s, but will point out the inner-quartile spread
for temperatures at most points in our forecast is quite large, as
much as 15-20 degrees of spread. This highlights the large amount of
uncertainty within the pattern, as well as difficulty in
pinpointing severe weather potential in the extended outlooks.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 623 PM CDT Mon Apr 29 2024
VFR conditions are expected to remain for the duration of the
TAF period. A strengthened pressure gradient will result in
breezy conditions tomorrow afternoon with gusts as high as 30
knots. There is a potential for some scattered showers during
the morning hours and thunderstorms at the end of the forecast
period however left out of the TAFs due to uncertainty in
intensity and timing respectively.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.
&&
$$
DISCUSSION...Krull
AVIATION...Collier
Area Forecast Discussion
National Weather Service Huntsville AL
1103 PM CDT Mon Apr 29 2024
...New AVIATION...
.NEAR TERM...
(Tonight)
Issued at 918 PM CDT Mon Apr 29 2024
Latest radar data indicates pockets of light rain spreading
eastward into northeastern AL at the current time, with an axis of
more widespread moderate-heavy rain and embedded thunderstorms
setting up across northeastern MS. Both regimes are occurring
within a region of deep/moist SSW flow, well ahead of a weak cold
front that should drift slowly southeastward across the Mid-MS
Valley and into southwestern KY/northwestern TN by 12Z as the
decaying cyclone that it is attached to lifts northeastward across
Lake Superior.
Recent versions of the HRRR model (as well as solutions from the
12Z CAMs) suggest that the axis of rain and embedded storms to our
west will continue to expand in coverage later this evening, as a
distinct mid-level shortwave trough (only partially phased with a
stronger northern stream disturbance ejecting into southwestern
Ontario) shifts east-northeastward from southern AR/northern LA.
The approach of this shortwave trough (and related SSW low-level
jet of 20-30 knots) should sustain the broader axis of precip as
it spreads eastward across our region, with rain/storms expected
to gradually diminish from SW-to-NE shortly before 12Z as the low-
level jet veers to WSW and weakens. Although deep-layer shear of
20-30 knots may result in some loosely organized storm structures
at times, CAPE will remain less than 500 J/kg and aside from a few
brief wind gusts up to 25-35 MPH, locally heavy rain and
lightning will be the primary storm impacts. Based on latest QPF
guidance from WPC, we are still anticipating widespread storm
totals between 0.5-1.5", with locally higher amounts.
Aside from minor updates to the POP/weather grids, other elements
of the forecast appear to be on track at this time, with lows in
the lower 60s.
&&
.SHORT TERM...
(Tuesday through Thursday)
Issued at 231 PM CDT Mon Apr 29 2024
Convection will gradually wane during the 12-18z window Tuesday
morning from west to east as the front shifts eastward through the
region. Cloud cover will dissipate by the afternoon as high
pressure builds into the area -- resulting in a sunny end to the
day Tuesday and a mostly clear night (some patchy fog may develop
early Wednesday morning). High pressure will continue to promote
tranquil conditions both Wednesday and Thursday -- with sunny/dry
weather forecast. A pronounced warming trend will again occur as
highs will reach the low to mid 80s on Wednesday and the mid to
upper 80s on Thursday.
&&
.LONG TERM...
(Thursday through Sunday)
Issued at 211 AM CDT Mon Apr 29 2024
An upper ridge pattern will continue to translate eastward into the
mid/southern Atlantic states heading into the end of the work week.
High pressure at the sfc will also remain layered from the NE states
into the Carolinas, resulting in afternoon highs climbing predom into
the mid 80s/near 80F both Thu/Fri. An upper trough axis will also be
rotating eastward thru the mid/northern Plains, with an attendant sfc
low lifting NE into the Great Lakes area. This sfc wave will help
drag a cold front eastward thru the Midwest/Mid South regions well
into the day Fri. Low-medium chances for showers/tstms (20-50%) will
develop along/ahead of the oncoming cold front late Thu into Fri. Sct
showers/tstms will then continue into the first half of the weekend,
as the frontal boundary moves SE thru the central TN Valley. Low
chances for showers/tstms (20-30%) will also linger thru the second
half of the weekend period, as the broad upper trough pattern moves
eastward across the region. Minimal low-level convergence/instability
coupled with better dynamic forcing displayed N/W of the area should
offset the prob for more organized/stronger tstms, with QPF totals
around 0.25-0.50 inches thru the upcoming weekend. Seasonably warm
temps will continue Sat/Sun, with highs mainly in the lower 80s/near
80F, while overnight trends predom in the upper 50s/mid 60s.
&&
.AVIATION...
(06Z TAFS)
Issued at 1103 PM CDT Mon Apr 29 2024
There have been no significant changes to previous aviation
forecast reasoning, as prevailing MVFR cig and vsby conds are
anticipated for an extended period thru 11-13Z as a band of mod-
hvy rain and embedded TSRA shifts eastward across northern AL.
Although the trailing/western edge of the precipitation band will
end within the timeframe noted above, additional but more
scattered shower activity is possible prior to the arrival of a
frontal wind shift to NW late tomorrow morning. A more pronounced
clearing trend will begin late Tuesday aftn, with clear skies and
lgt/vrbl winds perhaps resulting in the initial development BR/FG
btwn 4-6Z.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&
$$
NEAR TERM...70/DD
SHORT TERM...AMP
LONG TERM...09
AVIATION...70/DD
Area Forecast Discussion
National Weather Service Northern Indiana
800 PM EDT Mon Apr 29 2024
.KEY MESSAGES...
- Showers and a rumble of thunder possible this afternoon east of I-69.
- Additional chances for showers and thunderstorms expected Friday.
- Unseasonably warm through the week with temperatures 70s being
attainable.
&&
.DISCUSSION...
Issued at 312 PM EDT Mon Apr 29 2024
This afternoon`s pattern is characterized by a strong moisture
stream into the area with a connection to the Gulf, which allows
60+F degree dew points to remain across the area into tonight. With
the morning showers creating debris clouds, getting 1000 J/kg of
MUCAPE and decent low level lapse rates will likely be difficult.
Shear appears to be present, but only with pockets of 30 kts of
effective shear at best. It`s obvious on the NAM, but the ECWMF
shows shades of this as well, that there`s a sort of pre-frontal/
differential heating trough that also helps to limit any
thunderstorm production to east of I-69. If we can get some
instability to form, perhaps there could be some stronger storms
that develop as the NAM and to some extent the HRRR shows mainly
east of I-69. The main threat looks to be damaging winds and heavy
rain with the moisture loading present.
Mid level height rises signal the return of surface high pressure
for Tuesday providing a dry day. For Wednesday, a front passes
through with forcing dissipating and moisture being a little lower.
Perhaps a shower or storm could form, but don`t quite have
confidence on where with model disagreement still existing on timing
and moisture content. During this midweek period from Tuesday into
Thursday, a subtropical southeast CONUS ridge builds and the pattern
slows down allowing a trough across the Western CONUS and for
showers and storms across the Plains States and Mississippi River
Valley. As vorticity from the Western CONUS ejects northeast, it
wouldn`t be completely out of the question that a few counties could
receive a shower, but think much more of the messaging for this
period should be on it being dry. Highs will also be trending warmer
with low to mid 70s on Tuesday achieving highs securely into
the 80s on Thursday.
A resurgence of 60F degree dew points will be possible on Thursday
allowing it to feel more humid again, but a better chance of that
will be on Friday just out in front of a cold frontal moving in. The
ECMWF has 500 to 1000 J/kg, but the shear appears to be lower, which
may lessen the severity of it. The front appears to stall out along
US-24 or just south of the forecast area, call it in the
vicinity if you want, so am not quite ready to remove PoPs in
that area quite yet with some lingering instability noted on the
ECMWF. Sunday has a better chance to remain dry with mid level
height rises taking over and surface high pressure coming in
behind the now departing cold front.
That departing cold front looks to have stunted the southeast CONUS
ridge to some extent even if it still exists for Monday and Tuesday.
As such, with a cold front pushing through during this period and
60F degree dew points, we`ll have to watch for another chance for
showers and storms as long it times out favorably.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 722 PM EDT Mon Apr 29 2024
Slow moving cold front moving eastward this evening bringing
showers and a few embedded thunderstorms across most of the
area. KSBN still has a few light showers in the vicinity but
should dry out over the next hour or so. KFWA on the other hand
will continue to see light to moderate rain for the next
several hours as the front eases eastward and then a few
lingering light showers/sprinkles through 08z Tue or so. MVFR
conditions with lowered cigs and a few short periods during
heavier rains expected through 00z Tue for KSBN and through 08z
Tue for KFWA. VFR conditions will then return and will see
sky cover begin to trend clearer into Tuesday morning/afternoon
with mostly light northwest winds, a few gusts Tuesday afternoon
may approach 18 knots.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Roller
AVIATION...Andersen
Area Forecast Discussion
National Weather Service Jackson MS
1000 PM CDT Mon Apr 29 2024
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 952 PM CDT Mon Apr 29 2024
A few showers and isolated storms continue mainly across the
Golden Triangle this evening. Hi-res models suggest that another
short wave may kick off a few more shower/storms this evening
before dissipating and moving east of the area after midnight.
Stratus will develop overnight, with some areas of patchy fog.
Lows tonight will fall into the low 60s for most of the area./15/
&&
.DISCUSSION...
Issued at 309 PM CDT Mon Apr 29 2024
Decaying MCS from this morning continues to be our main
controlling feature and it has kept temps down and storms/precip
has been way earlier in the day. As noted earlier, this feature
has also used up instability and most moisture (lower level
transport) so recovery looks to be a challenge. 12z Hi-res
guidance continued to struggle with initialization, thus very poor
performance in the initial 12-18hrs. However, the latest Hrrr
(17z) seems to finally have a better handle. As a result, there
looks to be some showery activity in the tonight period, but it`s
a good bit less than prev runs indicated...thus lowered PoPs from
guidance to better illustrate this. Will keep some low end mention
of thunder across the E third as there seems to be sufficient
instability along with some decent forcing as the upper features
moves east overnight.
Moving into Tue/Wed...there may be some patchy fog in the S/SW and W
but confidence is not too high as lower clouds may limited that
potential. Overall, drier deep layer will be in place in the wake of
the system today and that should keep the area precip free.
Moisture returns for Thursday as return flow gets established and we
see this show up with a warm front like boundary translating
northward across the area. We will see the bulk of the short wave
energy to our N, but some waves will exist in the zonal type flow
regime. This introduces more uncertainty as these smaller scale
features will drive our local weather. First feature of note looks
to be on Thu. Most of the guidance shows this well at 700mb and this
could be just enough, and if timed right will daytime heating, to
support some strong to severe convection. This is day 4, so we have
some time to see how things go and how prev days (Wed) convection
may have any influence. Overall, just a period to watch.
Rain chances will remain in at least some part of the forecast area
Thursday through the weekend. This is in part due to decent moisture
making a return and favorable SW low level flow keeping the
trajectories in light to maintain. As noted about Thursday and the
potential short wave, the remainder of the forecast looks to see
something similar. Each day looks to be warm and some variation of
decent lapse rates around (typical for this time of year) so the
area looks to see decent instability develop. The key will be timing
the waves with heating or if a more robust wave develops. We also
look to keep a surface boundary near the area (it could waver
in/out) but this would also provide a potential focus for
precip/storms. Overall, a good bit of uncertainty exists from Friday
into early next week as variability is quite high in the guidance
suite. Nonetheless, it`s a period of days where we will need to keep
an eye on. Nothing looks like any widespread or all day type stuff,
but potential is in play to keep 20-60% type PoPs. The forecast will
get refined as we get closer. /CME/
&&
.AVIATION...
(00Z TAFS)
Issued at 658 PM CDT Mon Apr 29 2024
Most TAF sites are VFR this evening and this will continue into
the evening hours. Stratus will develop overnight and expect a mix
of VFR/IFR and possibly LIFR conditions. Expect the fog/stratus
to lift after 14-15Z on Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 63 82 60 87 / 40 0 0 10
Meridian 62 84 59 88 / 80 0 0 0
Vicksburg 64 83 61 88 / 20 0 0 10
Hattiesburg 64 85 61 89 / 50 0 0 10
Natchez 63 85 61 87 / 20 0 0 20
Greenville 64 82 62 86 / 30 0 0 10
Greenwood 64 82 60 87 / 50 0 0 10
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
15/
Area Forecast Discussion
National Weather Service Marquette MI
823 PM EDT Mon Apr 29 2024
.KEY MESSAGES...
- Isolated to scattered showers, some drizzle, and patchy fog
continues into tonight. Some fog may be locally dense at times
in high terrain, especially in the Keweenaw.
- Active pattern continues as a series of low pressure systems
track across the region into early next week. Above normal
temps/precip are expected including thunderstorm chances.
- Elevated fire weather conditions are possible over the west
half of Upper Michigan on Wednesday, but will depend on the
preceding precipitation.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 424 PM EDT Mon Apr 29 2024
RAP analysis has the weak 1006 mb low pressure system over northwest
WI with the negatively tilted trough over MN. Low level cloud cover
has kept the area fairly insulated today, limiting temperatures to
the 40s most of today. With some southeast downslope flow, a few
spots in the west may reach into the 50s yet this afternoon. With
ample moisture and periods of rain showers, patchy fog has been
observed in the METARs and on cameras, especially in the keweenaw
where upslope flow off Lake Superior has brought 1/4 mile
visibilities to Houghton County Memorial Airport much of today, only
to lift to 1/2 mile periodically. The sfc low is progged to slowly
meander over western Upper MI through this evening into tonight,
bringing an occluded front northeastward with it. This alongside PVA
from the mid level trough will yield some isolated to scattered
showers. With limited instability, only a few rumbles of thunder are
expected.
Showers/drizzle will lift northeast tonight as the midlevel trough
pivots over Lake Superior and the sfc low slowly weakens as it
meanders northeast with it. Areas of fog will continue, especially
in the wake of these showers and in upslope flow over the west,
especially in the Keweenaw. The continuing low clouds and fog will
keep temperatures tonight in the mid 30s to low 40s with warmer
temps in the east half of the UP. Additional accumulations through
tonight are forecast around 0.1" to 0.25".
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 415 PM EDT Mon Apr 29 2024
Period of active weather continues with a series of low
pressures systems tracking across the area into early next week.
There will be several chances for rain with these systems with
the best chance of widespread moderate rainfall likely occurring
with the system Thursday into Friday as models indicate a feed
of Gulf moisture ahead of it drawing in PWAT values in excess of
an inch.
Starting Tuesday, a mostly dry frontal passage will be moving across
the area tonight, but there may be some sprinkles/drizzle along and
ahead of the front. Model soundings indicate a potential for a few
hours of post-frontal upslope drizzle for the Copper Country Tuesday
morning associated with moisture wrapping around the surface low
tracking north of the area. Otherwise, expect mostly cloudy skies
with highs ranging from the 50s near Lake Superior and east to the
lower to mid 60s interior west and south central.
A vigorous 500 mb shortwave trough approaches from the Northern
Plains Tuesday evening as it becomes negatively tilted and pivots
across the area late Tuesday night into early Wednesday. There`s
very little time for moisture to return ahead of this disturbance
for destabilization and the nocturnal timing further limits thunder
potential. However, there`s very good agreement in convection riding
into the area along the cold front to our west Tuesday afternoon.
These storms appear to grow upscale into an MCS that moves fairly
rapidly across the area late Tue night into early Wed. At this
point, it looks like the best chance for widespread rainfall will be
aligned over the western counties and maybe some of the north
central counties closer to the system`s track and where the better
deep layer qvector convergence and isentropic ascent is fcst. Any
storms that make it into our area should be elevated and shouldn`t
pose a hazard. The window for rainfall is brief (~3 hours) leading
to light rain amounts less than 1/4 inch.
Not great agreement among the models with how much mixing will occur
on the backside of this system on Wednesday afternoon. The GFS
soundings show the potential of mixing to 6-7 kft through a fairly
dry airmass which could drop dew points into the lower 30s (and
perhaps lower) over the interior west with min RHs dipping to 30 pct
or less over the interior west half. Deep mixing off GFS soundings
also suggests westerly gusts could reach near 35 mph. Meanwhile, NAM
soundings depict more clouds with less mixing (only to 3-4 kft)
yielding lesser wind gusts (20 mph or less) and less afternoon
drying of dew points. If the GFS scenario of deeper mixing pans out
the combination of gusty winds and lower RHs could potentially lead
to elevated fire danger, however the recent moderate rainfalls over
the last week could also imply wetter soils/fuels that could limit
the threat.
High pressure builds in Wednesday night resulting in dry conditions,
but then the focus shifts to a low pressure developing over the
Plains on Thursday then tracking across our area Thursday night. As
a result, rain chances increase on Thursday ahead of the warm front
as it lifts north then rain chances end behind Friday`s cold frontal
passage. Ensemble probabilities indicate it`s likely that much of
the area should see QPF totaling a quarter inch or more during this
period with a chance (near 50 pct) of QPF reaching a half inch or
more south central.
Additional generally light rain chances look to continue through
next weekend as weak shortwave impulses continue to move through the
mid-level trough hanging over the area.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 822 PM EDT Mon Apr 29 2024
Flight restrictions will persist through the duration of this TAF
period due to low cigs and visibilities with a low pressure system
rotating just to the west of TAF sites. Ample moisture and
upsloping will keep CMX at VLIFR levels through tonight. And, SAW
and IWD will consistently remain at IFR/LIFR levels as well through
daybreak Tuesday. Look for gradual improvement to MVFR late
tomorrow morning with possible VFR conditions by afternoon at IWD
and SAW. CMX, on the other hand, will be kept at MVFR through
tomorrow afternoon. In addition, westerly winds will be breezy
at CMX tonight with sustained speeds above the 12 kt threshold
and gusts up to 20 kts.
&&
.MARINE...
Issued at 415 PM EDT Mon Apr 29 2024
East-northeast gales will quickly fall blo gales late this
afternoon/evening as the sfc low now over northwest WI gradually
lifts over central Lake Superior later tonight and winds become less
than 20 kts. East to southeast winds increase to 20-25 kts Tuesday
night, becoming westerly and increasing to 25-30 kts behind a cold
front on Wednesday. There is now less than 20% chance for westerly
gales up to 35 kts could occur on the windward side of the Keweenaw
shoreline. Winds quickly diminish below 20 kts Wednesday night and
stay light until the next low pressure approaches on Thursday
bringing another episode of gusty easterly to northeasterly winds
Thursday night into Friday with maybe a few low-end gale gusts to 35
kts possible over north central and eastern portions of the lake.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Small Craft Advisory until 11 PM EDT /10 PM CDT/ this evening
for LSZ240-241.
Small Craft Advisory until 4 AM EDT Tuesday for LSZ243>246.
Small Craft Advisory until 2 AM EDT Tuesday for LSZ247-248.
Lake Michigan...
Dense Fog Advisory until 11 PM EDT this evening for LMZ221-248-
250.
&&
$$
SHORT TERM...Jablonski
LONG TERM...Voss
AVIATION...TDUD
MARINE...Voss
Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Mon Apr 29 2024
.Update...00Z Aviation Discussion
&&
.SYNOPSIS...
Warmer temperatures are anticipated over the next several days with
highs rising into the low to mid 90s across the lower deserts. An
upper level trough will pass through the Intermountain West mid-week
resulting in breezy conditions across the region. Otherwise, dry
conditions will prevail across the forecast area through at least
this weekend.
&&
.DISCUSSION...
Benign weather conditions persist as quasi-zonal flow prevails
across the Desert Southwest. Afternoon RAP analysis showed longwave
troughing over the central CONUS while a shortwave trough is seen
pushing into the Pacific Northwest. Locally, the quasi-zonal flow
pattern will support continued dry westerly flow aloft, promoting
mostly clear skies, while 500 mb heights continue to rise to around
575-578 dm today. Temperatures will respond accordingly as
afternoon highs warm up several degrees above normal in the lower
90s. Widespread Minor HeatRisk will continue. Similar
temperatures are in the forecast for tomorrow as the tranquil
weather pattern persists before slightly cooling Wednesday.
For the middle part of the week, a shortwave trough will swing
through the Intermountain West while the core remains removed to the
north from our area. However, we will see a tightening gradient as a
result of this shortwave with an associated weak frontal boundary
pushing into the region going into early Thursday. An increase in
breezy conditions is expected Wednesday/Thursday with gusts upwards
of 20-25 mph possible across much of the area. Temperatures for
Wednesday and Thursday will see some slight cooling while remaining
near to slightly above normal. Lower desert highs during this time
will top out in the low 90s.
Heading into this weekend, uncertainty remains high in regards to
the potential for a deeper trough to affect the western CONUS with
varying ensemble solutions with the pattern evolution. The GEFS
continues to favor a deeper, amplified trough diving south along the
West Coast this weekend before moving inland across California. This
solution would favor a cooler, breezier weather pattern for our
area. Meanwhile, the EPS, though the latest run of the ensemble has
trended toward a deeper trough, keeps the greatest negative height
anomalies further north across the Pacific Northwest. Depending on
how this pattern evolves will dictate the amount of cooling and
breeziness we see for the end of the week and into the beginning
of next week. For now, NBM deterministic temperatures for the
latter part of the week keep lower elevation highs in the low to
mid 90s, while the interquartile range displays a continued large
spread given the aforementioned uncertainties. Despite the
uncertainty in temperatures, ensembles and deterministic models do
agree that dry conditions are favored to persist through this
weekend and into early next week and thus PoPs remain nil.
&&
.AVIATION...Updated at 2300Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT and
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected across the region during the
next TAF period. Winds will be light and follow diurnal
tendencies at most terminal locations, except at BLH, where a few
gusts near 20 kts may be observed prior to sunset. Extended
periods of variability are likely between directional shifts.
Clear skies will prevail through tomorrow afternoon.
&&
.FIRE WEATHER...
Warm and dry conditions will persist this week and into this weekend
with high temperatures around 3-5 degrees above normal each day.
Winds will be light and follow typical upslope/downvalley patterns
today and Tuesday before increased breeziness arrives Wednesday with
gusts reaching the 20-25 mph range across much of the area. Windy
conditions will also be possible across the western districts on
Thursday as a dry cold front passes through the Colorado River
Valley. Minimum relative humidity values will range from 8-15%
each day. Moisture recovery will range from poor to fair each
night, or around 25-50%.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Smith
AVIATION...RW
FIRE WEATHER...Smith/Salerno