Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/04/25
Area Forecast Discussion
National Weather Service Boston/Norton MA
806 PM EDT Sat May 3 2025
.SYNOPSIS...
Scattered strong to severe thunderstorms into this evening,
mainly across central and western MA and portions of northern CT.
An unsettled weather pattern with showers at times will persist
for the first half of the upcoming week with somewhat cooler
conditions.
&&
.NEAR TERM /THROUGH SUNDAY/...
Key Messages...
* Scattered strong to severe thunderstorms through 10 PM
* Severe weather threat remains NW of I-95, especially across
western/central MA
* Main severe weather threat is damaging straight-line wind
gusts
* Secondary concerns for hail and heavy rain/urban street
flooding
* Scattered showers at times overnight, but not a washout
Severe Thunderstorm Watch in effect for all of MA except for
southeastern MA, and portions of northern CT until 8 PM.
Latest SPC mesoanalysis showed surface-based CAPE values still
in the 1,000-1,200 J/kg range. However, mixed-layer CAPE values
were only about 250 J/kg. Cumulus clouds were more widespread.
Still expecting scattered strong to severe thunderstorms into
this evening, with storms weakening as we head towards sunset
and as storm move east towards the coast.
Effective shear was also on the higher side for a typical spring
day in southern New England, about 40-45 kt across the western
half of our region. Thus, the main concern will be damaging
straight-line winds, with a lower risk for hail.
As for timing, still really like the last few runs of the HRRR
to depict the general timing. Made some minor changes from the
earlier forecast. Initial round of thunderstorms should diminish
by midnight, with another round of showers possible across
north central and western MA later tonight. Still not raining
this entire time.
Minor tweaks to bring temperatures back in line with latest
observations.
Beyond the convection, the other issue for tonight will be the
extent of marine stratus with humid air moving over the cooler
waters. With more of a SW flow overnight, not thinking this will
get too far inland. That is not to say areas of low clouds and
fog will not develop anyway, will just be from a different
mechanism.
&&
.SHORT TERM /SUNDAY NIGHT/...
Key Messages...
* Scattered showers at times Sunday, but not a washout
A persistent front will meander back and forth across southern
New England Sunday and Sunday night. This will keep a chance of
showers in the forecast through Sunday night. Still not raining
this entire time. Have the greatest confidence in rainfall from
Worcester County west in MA and across northern CT. Rainfall
chances still a little less towards southeast MA. Instability
still appears rather limited, so thinking the threat of thunder
is sill too low to include in the forecast.
Above normal temperatures anticipated to continue, but not quite
as high as what we saw today during Sunday.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Messages:
* Closed mid-level low slowly moves to the northeast next week
and brings a soaking rain through Wednesday
* Ridging and a break from unsettled weather Thursday.
* Trough may bring cooler and unsettled weather by the end of
the week.
Monday Night and Tuesday:
Still have good agreement among guidance that a vertically
stacked low over the southern Great Lakes region will slowly
creep northeast through the week as the omega blocking pattern
holds strong. The slow movement will keep the region under the
most favorable upper- level divergence allowing ample
opportunities for soaking rain, and perhaps even a limited flood
risk across western areas. Ensembles continue to keep the best
forcing and heaviest rainfall to the southwest, but have ticked
subtly eastward into southern CT. Period of heaviest rainfall
during this bout of unsettled weather appears to be Monday night
through Tuesday morning when maximum divergence aloft will pair
with PWAT values of 1.5 - 2 STD above climatology. As a result,
ensembles have between 0.5 and 0.75 inches of QPF through
Tuesday morning. Dry slot moves in later Tuesday afternoon,
likely capping the threat for continued widespread heavy
rainfall.
Wednesday:
Omega block appears to finally break late Tuesday into Wednesday
morning allowing for a break in the pattern. Kicker shortwave
across southern Ontario begins to push the upper low to the west
Wednesday. The center of the upper-low winds up over our area
Wednesday afternoon. The associated cold pool is well
represented at 500mb where guidance has temperatures falling
to as low as -20C. Wednesday will bring the chance for
thunderstorm as lapse rates steepen during the afternoon.
Ensemble guidance has a 30-50 percent chance of CAPE values
above 500 j/kg on Wednesday, which likely warrants being
monitored going forward. Temperatures should remain in the mid
to upper 60s for Tuesday, with a decent chance (roughly 50
percent on the ensembles) the interior could rise above 70F for
Wednesday.
Later Next Week:
Better news for the later part of the extended forecast as a
broad upper level ridge builds over the north central CONUS
beginning later Wednesday night. A few lingering showers early
Thursday could give way to improving conditions in time for the
start of the weekend as high pressure builds over southern
Ontario. Relief from cooler conditions will be short-lived as
another shortwave brings a quick round of cool and unsettled
conditions Friday. Broad northern CONUS ridge appears to finally
make it over the CWA by the weekend.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00Z TAF Update:
Through Tonight: Moderate confidence overall, though low
confidence on the winds.
Weak frontal boundary with SCT SHRA/embedded TS from south of
OWD SSW to HFD is expected to lift northward through 04z.
Conditions are generally VFR outside of these showers. Brief,
temporary MVFR-IFR conditions as this boundary lifts north with
perhaps a rumble or two of thunder. As this front lifts north,
shower threat should come to an end. Cigs/visbys should
deteriorate to MVFR/IFR in stratus and fog, but the timing is
unclear.
North of the front, winds are light north to NE with winds south
of the front being S around 5-10 kt. Expect winds to become
southerly through the rest of tonight.
Sunday...Moderate Confidence.
IFR/LIFR conditions early in the morning should improve to
mainly MVFR thresholds during the afternoon. Scattered showers
will be possible at times, but we are not expecting a washout.
Sunday Night...Moderate Confidence.
Mix of MVFR with IFR/LIFR possible across the higher terrain.
KBOS TAF...Moderate confidence. Another round of SHRA/embedded
TS possible thru 03z with winds being light NE to N, which then
shift to SE/S. Cigs/visbys then deteriorate to IFR overnight
with S winds.
KBDL TAF...Moderate confidence. Another round of SHRA/embedded
TS possible thru 02z. Cigs/visbys then deteriorate to MVFR/IFR
overnight with S winds.
Outlook /Monday through Thursday/...
Monday through Monday Night: MVFR/IFR conditions possible.
Breezy. SHRA likely.
Tuesday: Mainly MVFR, with areas IFR possible. SHRA, isolated
TSRA.
Tuesday Night: MVFR/IFR conditions possible. SHRA, isolated
TSRA.
Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA,
isolated TSRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. Chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Moderate Confidence.
A front will remain nearly stationary north and west of the
waters into Sunday, then perhaps reach the eastern waters Sunday
night. This will maintain a risk for showers into Sunday night.
Gusty SW winds today should diminish tonight, and not become as
gusty Sunday. Small Craft Advisories continue as previously
posted. Areas of fog may result in pockets of visibility less
than 1 NM for a time late tonight into Sunday morning.
Outlook /Monday through Thursday/...
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.
Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.
Tuesday: Winds less than 25 kt. Seas up to 5 ft. Rain showers
likely, isolated thunderstorms.
Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Rain
showers, isolated thunderstorms.
Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.
Wednesday Night: Winds less than 25 kt. Seas up to 5 ft.
Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
ANZ231>237.
Small Craft Advisory until 11 AM EDT Sunday for ANZ254>256.
&&
$$
SYNOPSIS...Belk/FT
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...FT
AVIATION...Belk/Loconto/FT
MARINE...Belk/FT
Area Forecast Discussion
National Weather Service Burlington VT
1000 PM EDT Sat May 3 2025
.SYNOPSIS...
Intervals of showers and below normal temperatures will prevail on
Sunday with greatest potential of some dry weather near the
International Border. Temperatures will only warm into the upper 40s
to mid 50s, except mid 60s over the northern Saint Lawrence
Valley on Sunday. The unsettled and cool weather pattern
continues until early this upcoming week.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 958 PM EDT Saturday...Precipitation is increasing from
south to north once again as the next wave moves along the
stationary boundary draped over the North Country. Expect this
area of rain to expand northward overnight. Main adjustments
centered around increasing precipitation chances for southern
Vermont slightly ahead of schedule.
Previous Discussion...GOES-19 water vapor shows a deepening and
closing off mid/upper lvl cyclonic circulation over the central
MS River Valley with deep moist conveyor belt from the SE conus
into the Ohio Valley/NE conus. This deep moisture conts to
advect along a nearly stationary boundary from western PA into
southern/central New England and wl cont to be the focus for
additional showers tonight into Sunday. If you enjoyed the cool
and damp conditions of Saturday, guess what you are in luck
again for Sunday. As the flow remains strongly blocked tonight
into Sunday, expect plenty of clouds with additional showers and
some trrn enhanced qpf on the eastern side of the CPV/western
Slopes. Froude #`s <0.25 thru 00z Monday.
For tonight, we should see a brief break in the areal coverage of
showers this evening, per radar trends showing a narrow axis of
little rain over central NY/PA attm. Given small dwpt depressions,
light bl winds, and recent rainfall, areas of patchy fog are
possible in protected valleys and acrs the higher trrn tonight.
Meanwhile, additional deep layer moisture and elongated vorticity in
the fast confluent mid lvl flow wl race from southwest to northeast
with additional showers likely late tonight into Sunday. Both
GFS/NAM and ECMWF indicating a sharpening north to south pw and 850
to 500mb moisture gradient developing, which results in a
challenging pop/qpf fcst for Sunday, as sfc boundary remains south
of our cwa. The best mid lvl deformation and axis of moisture looks
to be from the High Peaks into central/southern VT, while near the
International Border could stay mostly dry on Sunday. Very difficult
to pin point the exact northern extent of precip, especially with
sfc high pres trying to advect drier dwpts southward. HREF 24hr
probability of qpf >0.25" is 60 to 80% along and south of a Tupper
Lake to Newport line on Sunday, with <5% over the SLV. THe
probability of qpf exceeding 0.50" in a 24 hour period on Sunday is
only 30 to 40% at most acrs central VT mtns on Sunday, which
indicates most of the rain wl be light again on Sunday. Have
utilized some high res NAM 3KM and 12z HRRR 2M temps to
highlight cooler temps within the rain axis on Sunday, while SLV
should warm into the mid 60s with drier conditions.
As 1028mb high pres tries to build southward toward our northern cwa
on Sunday night, the areal coverage of precip should become confined
to southern VT. Guidance conts to show a very sharp north to south
moisture gradient, making for a challenging fcst with regards to
placement of qpf/pops. A small 25 mile shift to the north, would
result in higher qpf/pops into central/northern cwa on Sunday night.
For now we have nil pops near the International Border to low likely
south of Route 4. Lows range from the mid 40s to lower 50s.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 330 PM EDT Saturday...An upper-level low will continue to spin
across Ohio as it slowly moves to the northeast closer to our
region. This system will stagnate due to an area of mid-level
deformation across Quebec and a blocking high off the coast of the
Canadian Maritimes. Decent moisture transport off the Atlantic on
Monday will keep precipitation chances around across southern
Vermont, but dry air associated with a col in northern New York will
help to limit shower activity in the northern regions of the area.
Although shower chances are lower to the north Monday, clouds from
upper-level subsidence will limit any sunshine. Shower chances will
continue Monday night across southern Vermont, increasing northward
by Tuesday morning, as the low gradually meanders to the northeast.
Shower activity looks to become more widespread Tuesday into Tuesday
afternoon with some instability developing across the St. Lawrence
Valley. Temperatures will be in the upper 50s to low 60s where
precipitation will fall in southern Vermont, but where drier air
exists to the north highs could reach into the upper 60s. Overnight
lows look to dip towards the low 50s for most Monday night.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 330 PM EDT Saturday...The pattern will remain stagnant through
the better portion of mid- week. The upper low will finally translate
over the area Tuesday night into Wednesday with the best chances for
precipitation Tuesday night in southern Vermont and Wednesday along
the international border. There is potential for some heavier
precipitation Tuesday night into Wednesday night with PWATs around 1
inch and aligned upper-level divergence with the moisture conveyor
belt. There are no extraordinary precipitation amounts over the 5
day period, but continued light precipitation could yield areas of
1-2" over the next 5 days. NBM probabilities of 72-hr amounts
greater than 1" are generally 20-40% with higher probabilities well
to our south. Any northward jogs of the low or convective elements
may skew towards the higher amounts, and we will continue to monitor
the conditions over the next few days.
As the upper low finally departs Wednesday night, a new upper low
will promptly replace it building in from the St. Lawrence Valley for
Thursday. Ensembles have trended the precipitation chances down with
a more progressive system. Shower chances look best in areas east of
the Greens on Thursday. If the trend holds, we may have a chance at
our first precipitation free Saturday. NBM probabilities still have
a 10-20% chance for precipitation, but that is definitely lower than
climo probabilities at 40%. Temperatures by late week look to be on
the cooler side with highs in the upper 50s behind the upper low,
however, a warming trend looks apparent by the weekend.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...With a break in rainfall, CIGs will improve
for most locations mainly to a mix of MVFR/VFR. The exception
will be at RUT where precipitation or low stratus will keep
conditions ranging mainly VLIFR to IFR. In this space of time
between rainfall, some fog may form elsewhere as well, but
extent and potential at terminal sites will be dependent on
cloud breaks. MVFR/IFR is expected to become more widespread
again 04-08Z as the next slug of moisture moves into the region.
MSS will be the odd one out staying on the periphery of lower
CIGs; one caveat could be some overnight fog should clouds break
more than expected. Otherwise, winds will not be much of a
concern to aviators with light winds becoming more northwesterly
on Sunday.
Outlook...
Sunday Night: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Monday: Mainly VFR, with local MVFR possible. Chance SHRA.
Monday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Tuesday: MVFR/IFR conditions possible. Definite SHRA, Slight
chance TSRA.
Tuesday Night: MVFR/IFR conditions possible. Chance SHRA.
Wednesday: Mainly MVFR, with areas VFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Chance
SHRA.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Taber
NEAR TERM...Boyd/Taber
SHORT TERM...Danzig
LONG TERM...Danzig
AVIATION...Boyd
Area Forecast Discussion
National Weather Service State College PA
1135 PM EDT Sat May 3 2025
.SYNOPSIS...
* Rain continues tonight with patchy fog possible on the
ridgetops.
* Largely beneficial multi-day rainfall event shaping up for
Sunday through Tuesday as an upper low swirls nearby; some
minor flooding will be possible with any repeated rounds of
heavy rain.
* Trending drier late week with a trend toward below normal
temperatures.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
The quasi-stationary or perhaps very slow moving cold front is
draped across Central PA this evening with an approaching upper
trough/closed low. Storms never quite got going tonight in south
central PA with meager instability in place, though a couple
discrete supercells dropped a swath of wind damage and large
hail across northern VA and MD this evening. The threat for
severe weather is now over, though a few thunderstorms remain
possible (if not likely) overnight across southeast PA as
convection continues to drift north ahead of an approaching
wrapped up surface low.
Overnight, multiple rounds of showers and a few storms will
continue across the region, with another quarter to three
quarters of an inch of rain expected by morning. Antecedent
precipitation deficits preclude any major flooding concerns, but
locations that receive significant rainfall tonight could be
primed for an elevated flood risk over the next few days as rain
continues.
Ample cloud cover and rainfall will keep temperatures quite mild
tonight. Lows by daybreak Sunday will range from the upper 40s north
of US-6 to the lower 60s in southeast PA. Low clouds will shroud
ridges across western and northern PA and patchy fog is possible
throughout the Commonwealth.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
A blocking pattern will remain over the fcst area Sunday into
next week with a deep/vertically stacked low in the OH Valley.
Southerly flow on the east side of the low will channel moisture
into the area with periods of rain and afternoon storms expected
Sunday through Tuesday. A few stronger storms are possible in
southwest PA Sunday afternoon thanks to the combination of
marginal instability, sufficient shear, and steep mid-level
lapse rates. The threat for severe weather appears to decrease
into next week.
While rainfall will be certainly beneficial and bring
some relief to drought conditions particularly in the southeast
part of the forecast area, we will need to monitor conditions
for repeated rounds of heavy rainfall which could produce
locally heavy totals and may result in localized flooding in
urban and poor drainage areas. WPC has maintained marginal
excessive rain risks for Saturday-Tuesday with a gradual
eastward shift of those areas coincident with a slowly advancing
upper low. Shower activity should trend more stratiform in
nature (as opposed to convective) as we get into next week,
which will limit the risk of heavy rainfall somewhat, but a
slight risk upgrade at some point would not be too surprising.
Ensemble means paint a widespread 2-3" across the region through
Tuesday, with locally higher amounts in thunderstorms.
This period will remain mild relative vs. climo with the
largest departures from normal in the overnight min temps
on the order of +10-20F above the historical average. Not much
in the way of sunshine.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The unsettled pattern continues into the long-term throughout
the middle of week as a closed low moves northeast of the area.
The bulk of heaviest rainfall will gradually begin lifting
northeast of the area Tuesday night through Wednesday night;
however, localized maxima across portions of the Endless
Mountains will retain some threat for urban and poor drainage
flooding across the northeastern sector of the CWA. Higher
confidence remains in this solution with model deterministic
guidance outlining favorable agreement.
Progressing into the end of the week, model guidance has
started to hone in on drier conditions prevailing by late
Thursday and into Friday; however, would realistically like to
see another cycle of dry conditions prevailing across the CWA
before nixing mentions at this time. Given there is some (albeit
shrinking) uncertainty, have decided to roll with NBM
throughout much of the late week period. Long range ensembles
prog high pressure building in by early Friday morning, leading
the signal for dryer conditions leading into next weekend.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
After 03Z Sun, thunderstorm chances decrease dramatically with
less instability present across the area. Increased low-level
moisture in the lower levels do warrant widespread MVFR-to-IFR
conditions as moisture increases across eastern Pennsylvania
under southeasterly flow. HREF model guidance is hesitant to
introduce IFR conditions at MDT/LNS until after 06Z; however,
given the aforementioned SE`ly flow have brought ceilings down
overnight with moderate (~50%) confidence. Lingering showers may
do well to quell the lower ceilings; however, and cannot rule
out low-end MVFR at MDT/LNS/IPT overnight before flow turns more
southerly. Further west, high confidence in BFD/JST prevailing
IFR after 02Z Sun with model guidance all pointing towards an
extended period of LIFR overnight into early Sunday morning. At
AOO/UNV/IPT, model guidance fairly well-resolved with IFR
ceilings and these seem plausible based on recent RAP model
soundings, thus have trended close to a combination of
HREF/GLAMP guidance.
Ceiling restrictions remain in place much of the day Sunday with
showers persisting. Slight improvement in the afternoon.
Outlook...
Mon-Tue...Frequent rain showers; some locally heavy with
prolonged sub-VFR conditions.
Wed-Thu...Showers become more scattered with higher chances in
the afternoon/evening hours. Restrictions possible.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Banghoff
NEAR TERM...Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...NPB/Bowen
AVIATION...NPB/RXR
Area Forecast Discussion
National Weather Service Indianapolis IN
933 PM EDT Sat May 3 2025
.KEY MESSAGES...
- Showers increasing in coverage this evening and tonight and
continuing through Sunday
- Showers Monday and Tuesday afternoon, then drier midweek
- Well below normal temperatures through Monday, then warming trend
to near normal through next week
&&
.FORECAST UPDATE...
Issued at 932 PM EDT Sat May 3 2025
Surface analysis this evening shows low pressure centered over
eastern KY, providing cyclonic flow across the region, including
easterly surface flow across Indiana. Regional radar suggests some
wrap around showers over IL and SW Indiana, circulating around the
upper low. Meanwhile more organzied and rain was found over OH and
points east, beneath a plume of upper level moisture as seen on
water vapor imagery. Temperatures were cool in the middle 50s.
Overnight, the upper low is expected to push to central KY,
continuing the cyclonic flow across the area. HRRR continues to
suggest that overnight wrap around moisture will develop across a
large portion of Central Indiana. Current radar trends have not
supported this as amounts and coverage today and through this
evening have been quite limited. Will focus best pops overnight
across the southwest parts of the forecast area with much lower pops
elsewhere. Generally any amounts should remain rather light.
The clouds and ongoing precipitation will limit temperatures fall
overnight and ongoing lows in the upper 40s and lower 50s appear
good.
&&
.SHORT TERM (This evening through Sunday)...
Issued at 302 PM EDT Sat May 3 2025
Cloudy and dreary conditions will persist into early next week as an
upper level low meanders around the Ohio Valley. Temperatures remain
well below normal this weekend with highs struggling to get out of
the 50s and low 60s.
Latest satellite and radar imagery shows the well advertised cut off
low spinning over St. Louis with widespread showers ahead of it
across Central Illinois and Western Indiana. The surface low is
centered over Cincinnati with a quasi deformation band setting up
over the IL/IN state line working to increase shower coverage and
intensity there. Steep mid and upper level lapse rates within this
band are resulting in a more convective component to the showers with
a few lightning strikes already observed this afternoon. Expect
lightning activity to be few and far between through this evening.
In addition to this band, an upper level wave rounding the base of
the trough and into Western Indiana is providing additional large
scale ascent for continued shower activity. This quasi-deformation
band plus the upper wave will keep shower activity across Western
and Southwestern Indiana through the evening before the systems
shift eastward overnight.
Expect rain shower activity to increase in coverage first over South
Central Indiana this evening, then northward toward the I-70
corridor and Indy Metro overnight as the deformation band redevelops
overhead. While Indianapolis has largely escaped the heavier
convective activity over the past few days, confidence is increasing
in this band of more widespread, heavier showers impacting the area
overnight and tomorrow with rainfall amounts of a half to an inch
along the I-70 corridor and over an inch for Southwest and Western
Indiana. Due to the scattered nature at times of the showers, there
will be areas where rainfall amounts greatly vary over short
distances.
Lower confidence exists in the thunder and lightning potential
overnight as the deformation band redevelops over the I-70 corridor.
Forecast soundings do not indicate steep enough lapse rates aloft
for lightning to occur; however it is certainly plausible that short
term guidance is not handling the smaller scale processes occurring
within the deformation band. An isolated lightning strike is not out
of the question overnight, but have not added it to the official
forecast as confidence is lower.
Widespread clouds and shower activity continue into Sunday with the
greatest coverage of rainfall largely dependent on where the
aforementioned deformation band sets up and where it pivots. Higher
confidence exists in more widespread shower activity moving into
North Central and Western Indiana tomorrow morning and early
afternoon with more scattered coverage for Central Indiana. The
presence of rain and clouds will keep temperatures well below
average with temperatures struggling to get out of the low 50s
tomorrow!
&&
.LONG TERM (Sunday night through Saturday)...
Issued at 302 PM EDT Sat May 3 2025
A blocking pattern continues into the long term; however there are
signs of a few drier and warmer days towards the middle and end of
next week.
Before drier weather arrives, Central Indiana will still be under
the influence of a stubborn upper level low Monday, and to a lesser
extend on Tuesday. Scattered to numerous showers will continue
during the day Monday for all of Central Indiana. At the moment,
similar chances for rain exist for the entire region, with the
greatest coverage of showers during the afternoon and evening hours.
As Monday approaches and smaller mesoscale details and boundaries
can be resolved, more detail will be added into the forecast
regarding which areas may see more widespread showers than others.
As of now, it appears that Central and Eastern Indiana could see a
better coverage of showers Monday as the main energy from the upper
low begins to shift east. Depending on how widespread rainfall is
Monday, highs may need to be lowered from what they currently are in
the forecast. Kept highs in the mid to upper 50s for Monday,
however thinking that areas under heavier rain showers may not make
it out of the lower 50s, especially in the east.
The upper low finally begins to move on Tuesday, pushing northeast
over Lake Erie. Enough lo level moisture hangs around Tuesday,
especially for eastern and northeastern portions of the state for
scattered showers to develop during the afternoon hours as weak
waves of energy rotate about the upper low. Relatively drier air
from the west in addition to increased boundary layer heating as
clouds break up will begin the warming trend with highs almost 10
degrees warmer than Monday. Cannot rule out an isolated thunderstorm
tuesday afternoon along and east of the I-65 corridor if enough
surface heating takes place.
Towards the middle and end of next week, significant differences in
model handling of the blocky pattern and particularly the second low
pressure system leads to lower confidence and thus lower PoPs later
in the forecast period. Longer range guidance has trended slower and
a bit further south with the next approaching low and associated
boundaries. While low PoPs remain in the forecast most days in the
long term, it looks like a good portion of Central and North Central
Indiana could be on the warmer and drier side of the system with
higher chances for any rainfall in Southern Indiana and toward the
Ohio River. Will watch the Wednesday-Friday timeframe closely
over the next few days as long range guidance handles cut off lows
relatively poorly.
Keeping temperatures close to average in the upper 60s and low 70s
for the remainder of the long term period; however expect some
changes based on where the highest threat for rainfall sets up. A
drier forecast would likely lead to temperatures warmer than what is
in the forecast, and vice versa.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 712 PM EDT Sat May 3 2025
Impacts:
- Widespread MVFR cigs expected this TAF period.
- IFR cigs will be possible on Sunday.
Discussion:
An upper level low pressure system is expected to linger across
Central Indiana over the next 24 hours.
Ongoing radar trends suggest precipitation currently is contained to
the SW parts of the forecast area. As the upper low pushes to KY
tonight, the HRRR suggests a band of wrap around precipitation
developing across Central Indiana and persisting through much of
the night. Thus have used mainly a VCSH mention for the first 6
hours until the more organized and area of precipitation expected
to develop later arrives. Prevailing rain with MVFR cigs will be
used at that time.
With the upper low remaining in the vicinity on Sunday, continued
VCSH is expected on Sunday with MVFR or worse cigs.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
SHORT TERM...CM
LONG TERM...CM
AVIATION...Puma
Area Forecast Discussion
National Weather Service Miami FL
706 PM EDT Sat May 3 2025
...New AVIATION...
.SHORT TERM...
(Rest of today through Sunday)
Issued at 1238 PM EDT Sat May 3 2025
A deep layer trough over the Mississippi and Ohio valleys is the
main weather feature to influence South Florida`s weather this
weekend. A lead/minor shortwave associated with this trough is
moving over the eastern Gulf and Florida peninsula today. This
shortwave, albeit weak, is interacting with slowly increasing low
level moisture to aid in the development of scattered showers
over SE Florida so far today. This will also contribute to
additional scattered showers and a few thunderstorms developing
this afternoon as low level instability increases and seabreezes
push towards the interior of the peninsula. A consensus of the
high resolution, convection-allowing models show initiation
across the interior south of Lake Okeechobee, and eventually
moving N-NE towards the Lake Okeechobee area and western suburbs
of SE Florida late in the afternoon and early evening, possibly
lingering until 10-11 PM. The presence of dry air aloft is the
primary limiting factor preventing any widespread or strong
storms.
The deep layer trough closes off at the mid/upper levels over
Tennessee and Kentucky tonight and Sunday, with the associated
surface cold front moving into the NE Gulf and Florida panhandle.
Showers and thunderstorms currently over the northern Gulf coast
ahead of the front will progress eastward through tonight, and at
least some of the model guidance (the HRRR for example) show precip
moving onshore the Florida Gulf coast late tonight and across SW
Florida by Sunday morning, while most of the model guidance keeps
the precip west of our area until later on Sunday. Moisture levels
continue to gradually increase in the S-SW flow ahead of the front,
with precipitable water values approaching 1.5 inches along the SW
Florida coast by daybreak Sunday. This along with increasing upper
level dynamics associated with the southern branch of the jet
stream, supports at least a slight chance of late night/early
morning showers or thunderstorms over SW Florida.
As the day progresses on Sunday, ingredients come together for more
numerous showers and thunderstorms across South Florida. This
activity should begin materializing during the late morning or
midday with daytime heating and broadly convergent low level flow,
then concentrate/shift E over the eastern half of South Florida
during the afternoon as enough of an Atlantic seabreeze acts as
the primary low level focusing mechanism. Model guidance suggests
CAPE values increasing to 1200-1800 J/kg, 0-6 km shear of up to 30
knots, and 500 mb temperatures of -11 to -12C across South
Florida. Accordingly, the Storm Prediction Center has SE Florida
in a marginal (Level 1 of 5) risk of severe thunderstorms on
Sunday. Given the amount of instability, large hail and strong
winds are the primary threats, but a tornado is not out of the
question if individual thunderstorm cells can interact with the
east coast seabreeze. The other main threat on Sunday is heavy
rain/localized flooding over metro SE Florida. Ensemble and
probabilistic model guidance is showing median precipitation
amounts of 0.25 to 0.75 inches, but the 90th percentile is up to
1.5 inches and the LPMM is suggesting isolated amounts which could
reach at least 3 inches. This would be beneficial rainfall for
parts of South Florida, but will have to be watched closely in the
event that higher amounts materialize and lead to flooding
concerns over the metro area.
Temperatures this afternoon will top out in the lower 90s over
interior SW Florida, and mid 80s over most of the metro areas along
both coasts. After a mild night with lows in the 60s and lower 70s,
highs on Sunday will range from the mid 80s to near 90. Increasing
clouds earlier in the day on Sunday could prevent some areas from
reaching these values.
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 304 PM EDT Sat May 3 2025
Model sfc analyses depict a trough/low complex racing across the
Ohio valley on Monday, with an associated decaying frontal boundary
extending southward into central Florida. The influence of the
lingering boundary will keep winds across SoFlo with a S/SW
component, bringing moisture advection and increasing chances of
rain. The main adjustment to the overall forecast scenario is that
ensembles and CAMs are now expanding coverage across basically the
whole area, with 60-80 POPs Monday afternoon. Best chances remain
over interior areas and the Lake region.
Pressure gradients seem to remain relatively relaxed Monday
afternoon, which will again allow for daytime heating and sea breeze
circulations to become focal points for deeper convection. Some
thunderstorms may become strong, especially with sea breeze
boundaries pushing inland early in the afternoon. Also, model
soundings continue to suggest a possible layer of colder air
intruding the mid levels, with 500mb temps in the -13/-14C range.
This may enhance deeper convection and stronger updrafts, which may
result in a few storms becoming very strong or even severe at times.
Models push the aforementioned trough/low complex further north,
with the decaying boundary being quickly replaced by a drier air
mass on Tuesday. Mid level flow shifts to the NW, while sfc winds
becomes easterly and weaken. A modest drying trend begins with POPs
in the 30-40 percent range Tuesday afternoon, and 10-20 percent
Wednesday and Thursday. Can`t rule out a few quick showers,
especially along the Atlantic coast and the Lake area each
afternoon, but most of SoFlo should remain generally dry. Another
trough/low system develops over the E CONUS on Thursday and sends an
associated frontal boundary towards Florida. This will bring back
increasing moisture and chances of rain to end the work week.
Temperatures are expected to remain around or slightly warmer than
normals, with highs in the mid-upper 80s for coastal locations, and
into the low-mid 90s over inland/southwest areas. Heat index values
will reach the 90s on the warmer days this week.
&&
.AVIATION...
(00Z TAFS)
Issued at 658 PM EDT Sat May 3 2025
Lingering showers and storms should dissipate over the next couple
of hours. Additional chance for storms impacting sites Sunday
afternoon, especially for the eastern sites. Periodic reduced
ceilings possible with shower and thunderstorm activity.
&&
.MARINE...
Issued at 1238 PM EDT Sat May 3 2025
High pressure moving away from the region will cause winds to
slowly decrease Sunday and Monday. Winds become southerly Sunday
and Monday, then back to SE Tuesday and Wednesday as high pressure
attempts to rebuild back into Florida from the Atlantic. Winds
look to remain 15 knots or less with seas generally less than 4
ft. Showers and thunderstorms will become more widespread across
the local waters, primarily Sunday through Tuesday.
&&
.BEACHES...
Issued at 1238 PM EDT Sat May 3 2025
The rip current risk at the Atlantic beaches will continue to
gradually decrease through the weekend. A lingering moderate risk
will remain this afternoon and possibly on Sunday, before
decreasing further next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 74 86 74 85 / 20 60 30 60
West Kendall 71 88 71 88 / 20 60 30 60
Opa-Locka 73 88 73 87 / 30 60 40 60
Homestead 73 86 73 86 / 30 60 30 50
Fort Lauderdale 74 85 73 83 / 30 60 50 70
N Ft Lauderdale 73 86 73 84 / 40 60 50 70
Pembroke Pines 75 90 75 89 / 30 60 40 60
West Palm Beach 71 87 70 85 / 40 60 60 70
Boca Raton 73 87 72 86 / 40 60 50 70
Naples 71 86 70 87 / 30 40 30 50
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...Molleda
LONG TERM....17
AVIATION...Rizzuto
Area Forecast Discussion
National Weather Service Melbourne FL
944 PM EDT Sat May 3 2025
...New UPDATE...
.KEY MESSAGES...
Issued at 358 PM EDT Sat May 3 2025
- Rain and lightning storms increase late this weekend into early
next week, highest coverage forecast each afternoon and
evening.
- A few strong to locally severe storms are possible Sunday and
Monday, capable of large hail and damaging winds. The potential
for a tornado or two also exists closer to the coast.
- Drier and warmer conditions resume Tuesday and Wednesday.
&&
.UPDATE...
Issued at 930 PM EDT Sat May 3 2025
Dry and stable conditions in mid-upper levels won out this
evening, allowing only a few showers to develop and just one or
two lightning strikes. However, recent soundings (23Z XMR and 00Z
TBW) have shown erosion of the 700 mb inversion, allowing a few
showers to continue on early tonight on lingering boundaries.
Expect this activity to diminish over the next hour, then the
question becomes rain and storm chances towards morning. HRRR has
been wildly inconsistent, presenting new solutions every couple
runs, and recent RAP runs are just as pessimistic as the 12Z CAMS.
As a result, confidence in any particular forecast is low, and
have lowered PoPs through the overnight and first half of Sunday
to reflect. Otherwise, no significant changes to the forecast.
&&
.PREVIOUS DISCUSSION...
Issued at 358 PM EDT Sat May 3 2025
Current-This Evening...KMLB radar shows the east coast sea breeze
moving inland, sparking isolated showers along the Treasure Coast.
Scattered showers (20-30%) remain in the forecast late this
afternoon as the sea breeze continues to progress inland. Confidence
remains low in lightning strikes or storm development due to dry
air aloft and a steep inversion around 700 mb. Dry conditions
build into the evening with temperatures falling into the 60s and
70s.
Tonight-Monday...A weakening cold front slowly slides across north
Florida, increasing moisture and rain chances locally. South to
southwest flow should generally favor the inland progression of the
west coast sea breeze each afternoon allowing a sea breeze collision
on the east side of the peninsula. This increases confidence in
shower and storms in vicinity of the I-95 corridor late each day.
How things evolve across the interior prior to a sea breeze
collision remain more uncertain with a wide spread of solutions
across global and mesoscale models on Sunday.
Mesoscale models have indicated development of showers and storms
moving onshore the west coast of Florida overnight. There is low
confidence in how organized shower activity may be as it approaches
interior east central Florida counties ahead of sunrise. The current
forecast suggests isolated to scattered showers (20-40%) moving
across the interior near to before sunrise. At this time, the higher
coverage suggested by the HRRR seems to be an outlier, but will
monitor model trends through the evening and may need to bump up
PoPs a tad with the evening update. A delayed start to daytime
heating should then allow scattered afternoon showers to develop,
becoming numerous in coverage where the sea breezes converge
(~60-70%). Southwest steering flow will push showers and isolated
storms towards the east coast into the evening hours, while
gradually drying across the interior.
A drier start on Monday should kick off an earlier diurnal heating
pattern than what will likely be seen on Sunday. Scattered coverage
of showers and isolated storms early in the afternoon are forecast
to increase in coverage late in the day as sea breezes converge
across the eastern side of the peninsula. Similar to Sunday,the
highest coverage is expected along and east of the sea breeze
collision as showers and storms are pushed back towards the east
coast.
Conditions will be favorable for strong to marginally severe storms
each afternoon, with probabilities highest closer to the coast. The
potential for damaging wind gusts up to 60 mph is the main hazard.
Additional storm hazards include occasional to frequent lightning
strikes, coin-sized hail, and a low tornado risk.
High temperatures climb to range the mid 80s to near 90 across much
of the area on Sunday. However, any cloud cover due to early showers
and storms could keep highs a few degrees cooler. Upper 80s are
forecast across the interior Monday with mid 80s along the coast.
Low temperatures will mostly range the mid to upper 60s each morning
with low 70s possible along the coast.
Tuesday-Friday (modified previous)...A drier trend is forecast
through midweek as upper level ridging builds over the eastern Gulf
and FL Peninsula. A few afternoon showers and storms are not
entirely ruled out (15-30% chance), but many locations will stay dry
through Wednesday. As a result, warmer weather is forecast with
highs approaching the low 90s inland (upper 80s at the coast). By
Thursday and Friday, models depict an upper level low pressure
center cutting off over the ArkLaTex region, helping to drive a cold
front toward north FL. Increasing rain and storm chances are
forecast from Thursday into the first part of next weekend as the
front approaches and moisture increases. Depending on overall cloud
cover and rain chances, daytime temperatures will sink lower by a
few degrees on Friday and especially Saturday (mid/upper 80s).
&&
.MARINE...
Issued at 358 PM EDT Sat May 3 2025
Modified Previous...Small craft should continue to exercise
caution across the offshore Volusia and Brevard waters tonight for
south to southwesterly wind 15-20 kts. Otherwise, generally
favorable boating conditions are forecast to continue with seas
2-4 ft (up to 5 ft well offshore). Persistent southerly flow is
anticipated through the middle of next week.
Despite generally favorable winds and seas, increased rain and
lightning storm chances this weekend through Monday will lead to
periods of locally unfavorable boating. Cloud-to-water lightning
strikes, strong wind gusts, and even waterspouts are possible with
the strongest activity later in the weekend. The highest coverage
of storms is forecast each afternoon and evening.
&&
.AVIATION...
(00Z TAFs)
Issued at 730 PM EDT Sat May 3 2025
A few showers have briefly developed across the forecast area this
evening, though dry air looks to be prevailing overall. Thus, have
removed any mention of precipitation for the remainder of the
evening and overnight hours. That said, a rogue shower cannot be
ruled out through around 2Z. VFR.
Model guidance continues to differ on precipitation chances
Sunday, especially in the morning. However, the formerly bullish
HRRR has begun to back off slightly, especially across northern
and central portions of the area. Have maintained a VCSH mention
for most terminals from around 13-16Z, though this is low
confidence. Then, tapering off from MCO/ISM northward, until
further development of VCTS area-wide in the afternoon (after
18-20Z). Lingering dry air will be an inhibiting factor. Although,
should any storm develop, dry air will lead to the threat for
strong wind gusts. Outside of convection, southerly winds
prevailing at 5-8kts overnight and 10-15kts Sunday. The east coast
sea breeze will back winds southeasterly along the coast in the
afternoon, while the west coast sea breeze reaches LEE by 20Z and
leads to southwesterly flow there.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 68 87 66 84 / 30 60 30 60
MCO 69 89 68 88 / 20 70 40 60
MLB 70 87 68 85 / 20 70 60 70
VRB 69 87 67 85 / 30 70 70 70
LEE 69 85 68 86 / 20 60 20 60
SFB 69 88 67 87 / 30 70 30 60
ORL 70 87 69 87 / 20 70 30 60
FPR 68 87 67 85 / 30 70 70 70
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
UPDATE...Haley
AVIATION...Leahy
Area Forecast Discussion
National Weather Service Missoula MT
230 PM MDT Sat May 3 2025
.DISCUSSION...
KEY MESSAGES:
- Gusty outflow winds and lightning possible this evening.
- Brief cool down with raw backcountry conditions Sunday-
Monday, then back to summer-like conditions thereafter
- Breezy Thursday (westerly winds 20-30 mph western Montana)
- Thunderstorms return at the end of the week.
The anomalously warm ridge is making it feel very summer-like
across the Northern Rockies this afternoon. With plenty of
sunshine, temperatures have risen well into the 70s across western
Montana, and across north-central Idaho temperatures range from
the 60s in the Camas Prairie to the 80s in the Hells Canyon.
Glancing at the water vapor satellite imagery across the western
U.S., a very large north-south trough exists from Southeastern
Alaska east and south towards southern California. The southern
half has a negative tilt which is providing plenty of lift for
widely scattered thunderstorms over the Sierra Nevada Mountains
into Nevada, the northern half is showing signs of pinching off.
This trough will track eastwards across our region Sunday into
Monday.
The dry cold front this afternoon was found generally from the
Idaho Panhandle southwards into the Camas Prairie. Temperatures
along and behind the front are running 10 degrees cooler at this
time yesterday. There was a thin line of rain showers behind the
front in eastern Washington and Oregon, technically considered
`anafront precipitation`. Visible satellite depicts cumulus
clouds developing over Lemhi County and over the southern
Bitterroot. This synoptic setup is good for mid to late afternoon
showers and thunderstorms being initiated off the mountains, and
along the approaching cold front. The latest RAP forecasts depict
500 J/KG of mixed layer CAPE over the southern Bitterroot Valley
and northern Lemhi County late this afternoon which could be
enough for a few storms to develop. Gusty winds near 40 mph, and
lightning are possible across eastern Idaho County, and west-
central Montana through the evening hours. Scattered showers and a
few storms are possible tonight.
On Sunday, the cold front will shift southeastwards across
southwest Montana and Lemhi County. Again were looking at
possible showers and thunderstorms in these areas with gusty winds
near 40 mph and lightning the main threats. Snow levels will fall
to around 5000 feet and there will be snow showers at times in
the mountains of Idaho into far western Montana Sunday morning.
Snow levels fall to around 6500 feet Sunday night across southwest
Montana with a dusting of snow possible at Lost Trail Pass, and
Georgetown Lake.
Scattered showers are possible on Monday as the weather system
slowly departs to the east. Northeast breezes are expected. It
will be chilly in the back-country with highs only reaching the
40s, northeast breezes, and occasional snow or graupel showers
above 5500 feet.
A milder and drier pattern ensues Tuesday and Wednesday and could
last through the rest of the week for many folks as temperatures
will rebound back into the 60s, 70s and 80s. A disturbance could
bring breezy westerly winds and a few showers on Thursday, but it
will remain mild. There is about a 30 to 40 percent chance for
wind gusts greater than 30 mph across northwest Montana and along
the Divide on Thursday afternoon. The probability for highs in the
80s in the valleys range from 70 to 80 percent on Wednesday,
Friday and Saturday! Though Friday and Saturday will bring a
chance for spring thunderstorms along with hail, lightning, gusty
winds and rain (and photogenic rainbows!). The NBM shows 60 to 70
percent chance for instability that could support storms across
the region during this timeframe except for northwest Montana.
&&
.AVIATION...A cold front is currently over the Washington/Idaho
border and will be slowly moving through the Northern Rockies over
the next 24-36 hours. A plume of showers and potential
thunderstorms is anticipated to develop ahead of the front and
affect portions of western Montana this evening. Storms will be
near KHRF around 03/23z, KMSO by 04/01z and KGPI around 04/03z.
The extremely dry low levels will allow for the potential for
gusty and erratic winds from any storms.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
Area Forecast Discussion
National Weather Service Omaha/Valley NE
604 PM CDT Sat May 3 2025
.KEY MESSAGES...
- Pleasant weather continues this afternoon with light winds and
few clouds. Very low end chance (<5%) for a scattered stray
shower across the far south and east.
- Slightly breezier for Sunday but still expecting a pleasant
day with minimal clouds and warmer temperatures in the low to
mid 70s.
- PoPs return late Tuesday through Thursday, with a 30-50%
chance of rain on Wednesday. Severe weather is not expected.
&&
.DISCUSSION...
Issued at 232 PM CDT Sat May 3 2025
.SHORT TERM.../Today through Sunday Night/
GOES-16 day cloud phase imagery shows a scattered cumulus field
across the southern half of our forecast area this afternoon.
Temperatures have warmed to the mid 60s as of 18z with light winds
also observed. These pleasant conditions are largely driven by a sfc
ridge with RAP objective analysis showing the axis located near
southern Wisconsin southwestward into Iowa and eastern Nebraska.
Aloft, a PV anomaly is observed across eastern Missouri where a 500
mb cutoff low is based. Wrap around cyclonic flow from this feature
and a weak ribbon of vorticity may generate very weak showers across
our far eastern and southern forecast areas, but confidence in this
occurring is very low. Lows tonight will reach the upper 30s to low
40s under mostly clear skies and calm winds.
The sfc high will move eastward during the day Sunday with generally
pleasant conditions expected. Highs Sunday will be in the low to mid
70s with minimal to no cloud cover expected. Winds may be slightly
breezy across our far northwest during the afternoon given the sfc
high departure and developing Wyoming sfc low inducing a pressure
gradient. BUFKIT soundings show mixing up to 800 mb, tapping into a
weak 15-20 kt LLJ. Winds relax into the evening hours with low
temperatures in the low to mid 40s.
.LONG TERM.../Monday through Friday/
Omega upper air pattern will dominate a large portion of the US
through at least the first half of the work week as two mid to upper
level lows, one centered over the Ohio River Valley and the second
over the Arizona/Four Corners area, sit and spin across these areas.
A large portion of the Northern and Central Plains will be
sandwiched between these two features and influenced by an upper
level ridge. This will help quell any precip chances through at
least Monday.
Late Monday night into Tuesday, the omega pattern will begin to
break down as the 500 mb southwest US closed low begins to move
northeastward toward the Central Plains. Q-vector convergence
overspreads much of the forecast area by Tuesday afternoon through
Wednesday. NBM brings PoPs back as a result Tuesday evening (15-20%)
across our far west and south, but uncertainty does exist in how
likely any precip would develop as soundings don`t appear to show
much deep layer saturation. Better moisture transport will arrive
early Wednesday morning helping achieve deep layer saturation,
with NBM painting widespread 30 to 50% PoPs during the daytime
hours Wednesday. PoPs may linger into Thursday across our south
as the upper level low lingers over the Central Plains before
diving southeastward Friday and Saturday. As far as precip
amounts go, only expecting a few hundredths of an inch across
the majority of the CWA, while areas across our far south near
the Kansas border could see a little more than a tenth of an
inch.
Some elevated instability is noted on Wednesday from soundings, so a
few rumbles of thunder are certainly plausible, but confidence in
seeing severe weather is really low. Some of the Euro ensemble
severe weather probabilities show less than a 5% chance of some
severe threat, but GEFS based CIPS and CSU probabilities seem to
disagree and show no severe potential across our forecast area.
Upper level ridging will make its way back to the Central and
Northern Plains late next week, with sfc high pressure helping
suppress PoP chances. Temperatures for the extended period will
largely remain in the upper 60s to low 70s, but will also see the
advancement of a 1000-500 mb thermal ridge Monday, Tuesday, and
again on Friday, resulting in highs for those days reaching the
upper 70s to low 80s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 604 PM CDT Sat May 3 2025
VFR conditions will prevail through the forecast period with
little to no cloudiness. Light and variable winds early this
evening will become southeast at less than 12 kt tonight into
Sunday.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Castillo/KG
AVIATION...Mead
Area Forecast Discussion
National Weather Service Las Vegas NV
719 PM PDT Sat May 3 2025
.SYNOPSIS...A potent low pressure system will push through the
Desert Southwest this weekend and start of next week, which will
bring gusty winds, scattered showers and isolated thunderstorms, and
cooler temperatures to the region. Conditions dry out and
temperatures climb back to above-average through the week and
heading into next weekend.
&&
.UPDATE...Showers and thunderstorms continued across much of the
region this evening in an area of strong upper level diffluence
ahead of an incoming trough. PWATs did increase to 0.5-0.6 inches
through the day in many locations, but low levels remained dry per
the 00Z LAS sounding. This resulted in a minimal heavy rain threat
with generally under 0.10 inches reported with the precipitation,
though localized higher amounts around 0.25 inches of rain were
reported with the heftier, back building storms. The main impact
today has been sudden gusty outflow/microburst winds. Gusts over 40
MPH were reported with many showers and thunderstorms, and a few
severe gusts to around 60 MPH were reported at times. Continued
waves of precipitation is expected overnight as the upper level low
moves overhead. Strong forcing will allow for embedded isolated
thunderstorm due to rapid lift combined with weak MU CAPE that
lingers in the mid-level tonight. Made some edits to the overnight
precipitation chances forecast to reflect the latest trends and
current radar returns, but overall the general idea has not changed
from the previous forecast. The current area of showers and
thunderstorms will congeal and move into Nye, northern Inyo, and
Esmeralda counties this evening which is where the focus for impacts
will be through about 10PM PT. After that, development of
precipitation is expected further south in eastern San Bernardino,
Clark, and Mohave counties tonight after midnight. Continued threat
for lightning tonight, and expecting the sudden gusty wind threat to
slowly be replaced by a heavy rain threat as low levels moisten and
PWATs continue to climb. The Las Vegas NV Sunday morning traffic out
of the the valley should be prepared for rain impacting the commute.
In addition to the scattered showers and thunderstorms, snow was
noted on ALERT wildfire camera in the Sierra. A Winter Weather
Advisory went into effect in the Sierra this afternoon, and while
snow has been light so far, continued snow is expected tonight as
snow levels drop below 8000ft. 2-4 inches of new accumulation are
possible overnight and anyone who plans to hike in the Sierra on
Sunday who was planning for May, spring-time hiker will be
unprepared for new snow. The Winter Weather Advisory continues
through Sunday as off an on snow is possible at times.
Outside of the precipitation, gusty southwest winds developed today
as the pressure gradient increased ahead of the incoming system. The
strongest non-convective winds were on the eastern slopes of the
Sierra as well as in the Western Mojave Desert where gusts to around
40 MPH were reported. A wind advisory continues for the Western
Mojave Desert through early Sunday morning, and while winds may be
past their peak there continue to be gusts over 35 MPH that cross
the major highways. Will not be making changes to the wind headlines
at this time as continued wind impacts are possible, especially for
anyone driving through the area.
-Nickerson-
&&
.PREVIOUS DISCUSSION...519 PM PDT Sat May 3 2025
.SHORT TERM...Today through Monday.
A potent trough has pushed into the region today, with the center of
circulation expected to close off over the Desert Southwest tonight.
This system has ushered in moisture 150 to 250 percent of normal for
this time of year, coupled with synoptic ascent and daytime heating,
we have already observed scattered showers and isolated
thunderstorms this afternoon. Inverted V-shaped forecast HRRR
soundings show between 1000 and 1150 J/kg of DCAPE across the
forecast area this afternoon. These dry low levels will result in
strong gusty winds in excess of 50 mph from some of the stronger
thunderstorms. In fact, numerous 55 - 60 mph gusts were measured in
the southern portions of the Las Vegas Valley earlier this
afternoon, along with a 65 mph gust measured in the test site. Best
chances of shower and thunderstorm activity will continue to shift
northwestward through the remainder of the afternoon, with expected
impacts including locally heavy rainfall, frequent lightning, small
hail, and strong gusty winds. As mentioned in the forecast update,
the best chances for severe thunderstorms continue to be across
Esmeralda and central/southern Nye where SPC has highlighted a
"Marginal" Risk of severe-level winds. As the system closes off
tonight, ascent continues, despite the removal of daytime heating.
Another round of scattered showers and isolated thunderstorms will
pick up around 3 to 4am and will continue through the morning. There
will be a brief reprieve late-morning / early-afternoon before
convection returns in the afternoon thanks to daytime heating.
Moistening of the low levels will result in a lesser concern for
strong gusty winds tomorrow, but frequent lightning, elevated rain
rates, and small hail will continue to pose a threat. Convection
returns on Monday as the low pushes eastward out of our area, with
best chances of showers and thunderstorms in Lincoln, Clark, and
Mohave counties.
In addition to convection, increased pressure gradients as a result
of this incoming trough and a ridge of high pressure in the
southeastern Pacific will increase west-southwesterly winds today in
the western Mojave Desert (northwestern San Bernardino County).
Expect widespread wind gusts 25 to 35 mph with gusts 40 to 45 mph in
the higher terrain. As the trough axis pushes through the region
tonight, expect increased north-northwesterly winds across northern
Inyo, Esmeralda, and southern Nye counties.
Finally, the cold front associated with this trough will drop snow
levels to 8500 to 9500 feet tonight. As such, a Winter Weather
Advisory will go into effect for the eastern Sierra Slopes today at
5pm and will continue until 11pm Sunday night. Additionally,
temperatures will drop substantially between today and Monday, with
Monday`s afternoon highs reading between 10 and 14 degrees below
normal.
.LONG TERM...Tuesday through Friday.
The lingering affects of this weekend`s storm system will remain at
least into midweek with low chances for showers and perhaps a few
storms into Wednesday. This is in response to remaining cold air
aloft while temperatures gradually begin to warmup near the surface,
generating instability. From Thursday into the weekend, a noted
warmup is in store as broad upper ridging develops across the Desert
Southwest. This is well captured in the ensembles, which depict a
return to temperatures above seasonal normals and much drier
conditions as we near next weekend.
&&
.AVIATION...For Harry Reid...For the 00Z Forecast Package...
Convective activity around the valley this afternoon has stabilized
the atmosphere near the surface and allowed winds to diminish.
Prevailing winds through the evening should remain near or below 10
knots. However, there remains a low probability that an outflow
from distant storms could move into the valley and produce gusts
over 25 knots. Prevailing wind direction will continue from the
southwest until 12Z to 14Z, when a wind shift occurs from the north-
northwest. Guidance is also still showing an increase in shower and
thunderstorm activity between 10Z and 16Z, which may impact the
terminal directly. The threat of showers and thunderstorms persists
through tomorrow afternoon. With any of the stronger thunderstorms,
impacts could include locally heavy rainfall, brief drops to
MVFR/IFR conditions, small hail, and frequent lightning.
For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package... Conditions at the Las
Vegas area TAF sites will be similar to those described for Harry
Reid above. At KBIH, scattered showers will persist through the
evening and then redevelop after 19Z tomorrow. Showers and a few
storms are also likely near KDAG this evening and again tomorrow
afternoon, although winds will be stronger with gusts to 30 knots
possible well into the evening. Showers and a few storms are also
expected in the Colorado River Valley, although coverage should be
less than in areas further north. With stronger thunderstorms,
impacts could include locally heavy rainfall, brief drops to MVFR/
IFR conditions, small hail, and frequent lightning.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Soulat
LONG TERM...Austin
AVIATION...Planz
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