Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/21/25
Area Forecast Discussion
National Weather Service Wichita KS
645 PM CDT Sun Apr 20 2025
.KEY MESSAGES...
- Strong to marginally severe storms potential through 6pm this
evening.
- Warming trend Monday through Thursday, possibly turning a bit cooler
again by Friday.
- Periodic thunderstorm chances late Tuesday through Thursday
night or Friday.
&&
.DISCUSSION...
Issued at 116 PM CDT Sun Apr 20 2025
THIS AFTERNOON--EVENING:
Currently, widespread light to moderate rain, with pockets of heavy
rain and embedded thunderstorms, continue to progress north across
the region, as a powerful upper low approaches from the southwest.
Hourly rainfall rates have ranged from about 0.05-0.20", locally
higher. We`re expecting this widespread rain to gradually end from
southwest to northeast through the afternoon and early evening.
While widespread flooding concerns aren`t expected, pockets of heavy
rainfall falling over saturated soils may support localized minor
flooding, especially over far southeast Kansas where 2-4" rainfall
amounts have already occurred with this storm system the past 2
days.
Strong to marginally severe storm potential...In the short-term
(through 2-3pm), this threat remains confined to Labette-Neosho
counties, closest to the near-surface based instability and strong
low and deep layer shear profiles prevalent just to the east-
southeast. Main threats with this activity will be small hail, 50-60
mph winds, and perhaps a brief tornado or two embedded within the
fast-moving broken squall line approaching from the south-southwest.
We`ll be monitoring radar trends for any possible warnings.
Further west (Cowley-Butler-Greenwood-Elk-Chautauqua counties) from
about 2-6pm closer to the upper low, steep mid-level lapse rates and
weak surface heating along with cold temperatures aloft could
produce enough surface-based instability for an isolated strong to
marginally severe storm threat. Latest HRRR soundings indicate
modestly long and straight hodographs, which would support splitting
low-topped supercells capable of marginally severe hail and perhaps
50-60 mph winds. Additionally, cannot completely rule out a brief
tornado, either from landspout processes in vicinity of the slow-
moving frontal zone, or weak supercell processes. We`ll be
monitoring radar trends for any possible warnings.
LATE TUESDAY--THURSDAY NIGHT OR FRIDAY:
Deterministic and ensemble consensus continues to support an active
period thunderstorm-wise, as a pair of cold frontal zones ooze south
through the region Tuesday evening-night, and again sometime
Wednesday evening through Thursday night. Per model climatologies,
forecast moisture and instability look to be seasonably high,
although effective deep layer shear appears to be only so-so.
Therefore, localized severe thunderstorms along with locally heavy
rainfall appear possible, but organized widespread severe weather
looks unlikely at this time. Mesoscale details from the previous
days convection will play a big part in the potential for any
subsequent thunderstorm chances beyond Tuesday evening/night, hence
it remains too early to start defining which days will have the
greatest potential for thunderstorms beyond Tuesday night.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 640 PM CDT Sun Apr 20 2025
Showers continue to dissipate as the upper level storm system
begins to lift rapidly northeast away from the area. This will
allow VFR to return from west to east as we move through the
evening hours. We could see some fog formation as we move
through the overnight hours, but breezy westerly winds could
limit formation. Breezy southerly winds will develop ove the
area on Monday with VFR anticipated.
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 PM CDT this evening for KSZ072-093>096-
098>100.
&&
$$
DISCUSSION...ADK
AVIATION...MWM
Area Forecast Discussion
National Weather Service Northern Indiana
858 PM EDT Sun Apr 20 2025
.KEY MESSAGES...
- Showers and a few thunderstorms will be possible tonight, but
severe weather is not expected.
- Chances for showers and perhaps some thunderstorms returns mid
to late week this week.
- Highs in the 70s to perhaps 80 degrees will be possible
Wednesday and Thursday.
&&
.UPDATE...
Issued at 858 PM EDT Sun Apr 20 2025
Convective chances will continue to be the primary short term
forecast issue to resolve through the overnight hours.
A potent upper level trough across northwest Missouri will
continue to lift northeast and into northwest Wisconsin by
morning. Additional deepening of low level reflection is
anticipated this evening through the early overnight via
primarily diabatic tendencies. This should allow stronger and
more veered low level wind profiles to take shape with best
low/mid level moisture transport through the early overnight
hours. 00Z sounding from KILX (Central Illinois) indicates
fairly impressive surface based instability around 1000 J/kg via
strong 725-600 mb lapse rates on the order of 8 deg C/km. Near
term RAP progs do rapidly advect these steeper mid level lapse
rates northward across the western/southern Great Lakes through
early evening which should trend to diminish pre-frontal
instability across much of the area by 06Z. Slight boundary
layer cooling will also act to create some more CIN for sfc
based parcels which may only leave approximately 200-500 J/kg
MUCAPEs for elevated parcels. IR cloud tops have shown a recent
warming trend with upstream convection across IL and would
expect this trend to continue through 04Z as downstream
instability gradually weakens. Given strongly forced nature to
setup, will make minimal changes to previous forecast with
likely PoPs overspreading the area from west to east overnight
along with slight chance/low chance thunder PoPs given the
elevated instability. Severe weather is currently not expected,
but cannot completely rule out a stray 40-50 mph gust across far
western portions of the forecast area during the early
overnight hours.
&&
.DISCUSSION...
Issued at 256 PM EDT Sun Apr 20 2025
The northern stream and southern stream jets are disconnected as the
northern stream trough evacuates to the east while an upper low that
slowed down in the southwest yesterday is picked up by a trough in
the west and carried towards the Great Lakes between today and
Monday. In between the squeeze play of these pieces, high pressure
nosed in last night to allow 30 degree dew points to sink into the
area. As precipitation attempts to enter from our southwest, this
high dew point depression airmass will act to limit rainfall output.
Later this afternoon, the NAM brings through a CAPE axis as a warm
front lifts north, but that`s only got around 300 J/kg in the moist-
bias NAM model. Once the warm front lifts north of an area, the NAM
brings in MUCAPE topping 1000 J/kg after 00z tonight, but it`ll
likely take until better forcing (associated with the occluded
front) can arrive (just after 6z) to lift the cap. It may be too
late to be able to tap into the better instability and is likely why
the convective schemes are quick to make the convection along the
front be outflow dominant. If the instability is slower to depart
the area or the arriving convection with the occluded front has more
momentum behind it or comes in earlier, then perhaps it could tap
into the better instability. It`s harder to see any stronger cells
erupt through the cap. At this point, will side with the forecast
non-severe thunderstorms as the more likely outcome. Otherwise,
could see gusty to strong winds and hail from stronger storms
overnight.
Dry air moves in behind the occluded front allowing rain to
dissipate in the morning and clouds to scattered out in the
afternoon Monday. As CAA takes over, mixing just below the departing
45 kt LLJ jet may be able to occur. For the most part, think 25 to
35 mph wind gusts will be possible as mixing starts to take hold,
but could see some 40 mph gusts along the front as it pushes
through. Also, for areas west of IN-31, the high temperature will
likely be in the morning before CAA comes in to cool the area down.
High pressure continues to keep the area dry on Tuesday and, while
it may start cooler than Monday starts, a warm front arriving late
in the day may help temps push into the 60s to around 70 degrees
before the day is done.
The aforementioned warm front stalls in Lower MI Tuesday night, but
there is some discrepancy on where it stalls out. The ECMWF appears
to be a southern outlier with the NAM more of a northern outlier.
This is important because guidance has an MCS-like system moving
along the front and causing some showers into Wednesday. Instability
appears to be lacking so thunder may be fewer and further between.
Then, a slow northward movement of energy from the south as a trough
approaches from the west brings a chance for showers/storms to end
the work week. The GFS is still much earlier with the arrival of the
weak energy from the south than the ECWMF and therefore brings its
rain chances in much earlier. The connection to the Gulf is present
in the ECMWF just not as strong. The ECMWF fills in much more of the
area on Friday with rain/storm chances whereas the GFS prefers
Thursday for the rain chances.
Either way, still expect high pressure to come in from the north for
next weekend bringing a return to cooler/drier conditions as an
upper low deepens over eastern Canada.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 800 PM EDT Sun Apr 20 2025
A potent upper level trough across northern Missouri early this
evening will continue to take more of a north-northeast track
into this evening. Best low/mid level moisture transport
northward into northern Indiana will occur in the 01Z-05Z
timeframe in advance of an associated cold front. This advective
forcing could be enough when combined with weak elevated
instability for a few showers to develop. Attention after 06Z
will turn to more strongly forced area of showers/embedded
thunderstorms current across MS River from northwest Illinois
into southeast Missouri. This line of showers/embedded storms
will begin to outrun a weakening instability axis by the 06Z
timeframe across extreme northwest Indiana. Confidence remains
high in a period of showers at terminals in pre-frontal zone
overnight, with lower confidence on thunder given weak nature to
elevated instability. Will maintain trend to MVFR cigs around
2k feet post-frontal late tonight into Monday morning before
likely improving to MVFR Monday afternoon. Good post-frontal
mixing/steep low level lapse rates will support gusts to around
30 knots on Monday.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT Tuesday for LMZ043-046.
&&
$$
UPDATE...Marsili
DISCUSSION...Roller
AVIATION...Marsili
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
630 PM CDT Sun Apr 20 2025
.KEY MESSAGES...
- Widespread showers with embedded thunderstorms tonight. A few
stronger storms with locally gusty winds possible, especially
south of I-80.
- Windy conditions on Monday with west-southwest gusts in the
35-45 mph range.
- Well above normal temperatures expected inland of the lake
for the rest of the upcoming week after a cool Monday.
&&
.DISCUSSION...
Issued at 258 PM CDT Sun Apr 20 2025
Through Monday Night:
A swath of showers is moving across northern IL early this
afternoon. These showers are blooming north of a warm front as
it progresses northward into our CWA. As of around 2 PM, the
boundary resides near the Kankakee River and conditions are dry
immediately along and behind it. A few embedded thunderstorms
and heavier showers have been clinging onto a MUCAPE gradient
immediately north of the front. The showers and embedded thunder
will continue to be pushed along by the front until they get
shunted north of the CWA late this afternoon and the area should
be largely dry then until later in the evening.
The warm front is expected to get hung up over our CWA, roughly
near the I-88/90 corridors later this afternoon before surging
northward again this evening with the approach of the low
center and cold front. A pretty sharp temperature gradient is
setting up across our area on either side of the front,
especially now that our south has dried out and is beginning to
see some sun. Temperatures should be rather steady this evening
while this front remains stationary. After the front begins its
trek northward again, much of the area north of I-80 will likely
even warm a couple of degrees tonight.
The storm`s cold front will propagate across the CWA late this
evening into tonight, bringing with it an additional push of
rain and probably some embedded thunderstorms. Continued low
level warm advection this evening will generate a pool of
elevated instability sufficient for thunderstorm development
just ahead of the cold front. While severe weather is not really
anticipated, we could see some stronger winds associated with
these storms. Several pieces of guidance are resolving a
corridor of gusty winds coincident with a narrow opportunity for
the low levels to become only weakly stable near the front. An
impressive low level jet will track just off the deck and it`s
very possible that some of these stronger winds could punch
through to the surface, especially with the heavy rain and
storms to help out. This is especially true closer to central
and western IL where they could maintain a little bit of mixed-
layer instability into the evening. An SPC marginal risk abuts
our southwest CWA for this wind potential.
The storms will be off to our east prior to daybreak tomorrow. A
trailing secondary cold front will move across the area during
the morning hours. In fact, morning low temperatures tomorrow
will likely occur well after daybreak behind this boundary. With
appreciable low level moisture hanging on behind the initial
front, some drizzle may materialize during the morning before
the secondary front passes. Conditions should also be windy
tomorrow, especially during the morning, but confidence is shaky
in what sort of winds we`ll be looking at. The lack of
confidence boils down to two primary discrepancies among models:
the magnitude of the low level flow and the quality of low level
moisture. The Euro and UKMET bring in much drier near- surface
air behind the initial cold front than other camps leading to
slightly deeper and overall more efficient mixing in the
morning. These are two of the more aggressive solutions for
winds tomorrow. 925mb winds during the morning are also being
modeled at anywhere between 35 and 45 kt. The HRRR for instance
is stronger with the low level flow so, despite being Monday
Night saturated in the low levels with lesser mixing, it`s
still wanting to resolve gusts to around 40 mph. So it`s tough
to say exactly what sort of flow we will have upstairs and how
efficiently we can mix that down to the surface. But a period of
at least 30 to 35 mph gusts looks likely tomorrow morning,
although 40 to 45 mph certainly looks attainable.
Winds could remain strong into the early afternoon but should
start stepping down during the afternoon as the low level flow
relaxes. After the morning drizzle potential moves away, no
rain is expected for the rest of the day. A feed of dry air will
chip away at the cloudy skies and some good sunshine should
fall on the area later in the day while afternoon temperatures
look to be in the 50s.
Doom
Tuesday through Sunday:
The upper level pattern across the CONUS will transition to more
of a quasi-zonal flow (west-to-east oriented) pattern for the
middle part of the week, before becoming more amplified again
later this week into next weekend. This is expected to curtail the
threat of any stronger (and persistent precipitation generating)
storm systems from impacting the eastern half of the country
Tuesday through at least Thursday. In spite of this, ensemble and
deterministic guidance are in agreement in tracking some smaller
scale perturbations eastward across our region during this
period. Accordingly, while there is likely to be mainly
precipitation free hours, there will be some on-and-off shots of
showers and thunderstorms through much of the week.
Guidance remains in good agreement with tracking an initial low
amplitude disturbance eastward across the Midwest into the western
Great Lakes through Tuesday night. Weak height falls associated
with this waves should encourage the development of a modest
southerly low-level jet and strengthen theta-a advection Tuesday
night. This will in turn support our first decent potential
(50-60% chance) for showers and storms late Tuesday into
Tuesday night. At this time the best chances for this reside
along and north of I-80. Another, similar quick moving impulse
may shift into the area and result in another period of (~30%
chance) of rain late Wednesday into Wednesday night. Otherwise,
our next good shot (50-60% chance) of showers and storms comes
late in the week (Thursday night into Friday) as a stronger cold
front moves across the area.
Temperatures are expected to be on a warming trend to solidly
above average temperatures through the middle of the week,
particularly for inland sections of northern IL and IN. As is
often the case this time of year, lake breezes each afternoon will
keep temperatures notably cooler along and near the Lake Michigan
shore. Temperatures are then likely to cool back closer to
seasonable levels next weekend following a cold front passage late
this week.
KJB
&&
.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 630 PM CDT Sun Apr 20 2025
Aviation forecast concerns for the 00Z TAFs:
- Scattered TSRA possible late this evening.
- MVFR ceilings develop overnight and persist through most of
Monday while slowly rising.
- Breezy ESE winds become WSW by morning. Gusts 30-35 kt
possible Monday, easing later in the day.
Surface low pressure was analyzed over MO early this evening,
with a northward lifting warm front extending southeast across
west-central IL into southwest IN. Breezy east-southeast winds
with gusts 20-25 kts will persist across the terminals this
evening ahead of the approaching warm front, eventually veering
southwest after midnight tonight as the low moves across WI and
the occluding frontal boundary shifts east of the area. West-
southwest winds are expected to strengthen in the wake of the
low, with gusts 30-35 kts likely during the morning and early
afternoon hours before diminishing quickly early Monday
evening.
High-res CAMs are in generally good agreement in bringing a line
of convective SHRA/TSRA (currently approaching the MS River from
eastern IA/MO) northeast into the area late this evening, with
some potential for isolated elevated SHRA/TSRA development
ahead of the main are of precipitation in strong warm-advection.
Thus have introduced a VCTS by 03Z/10pm and a tempo for TSRA in
the 04Z-06Z window (an hour earlier for KRFD). SHRA coverage
should diminish to scattered/widely scattered coverage during
the remainder of the overnight hours. Current VFR conditions are
expected to deteriorate within the heavier precip late this
evening, with MVFR ceilings likely then persisting into much of
Monday before eventually scattering to VFR from the west later
in the day/evening.
Ratzer
&&
.MARINE...
Issued at 258 PM CDT Sun Apr 20 2025
A Small Craft Advisory is in effect today. A Gale Warning goes
into effect tonight and lasts into tomorrow evening.
Low pressure at or just under 1000 mb will track from
Iowa tonight to northern Lower Michigan Monday afternoon and
across Lake Huron Monday evening. Breezy east-southeast winds
tonight will result in hazardous waves for small craft along
the Illinois and Indiana nearshores. A period of gales is also
possible late tonight coincident with a push of showers and
thunderstorms. Then in the wake of the system on Monday, winds
will quickly shift to southwest and then west while rapidly
increasing. While some uncertainty remains, felt confidence was
high enough to upgrade the watch to a Gale Warning for tomorrow.
Also made the decision to have the warning go into effect at 06Z
for the brief gale potential tonight.
Doom/Yack
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 1 AM CDT Monday for the IL and IN
nearshore waters.
Gale Warning from 1 AM to 7 PM CDT Monday for the IL and IN
nearshore waters.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
820 PM EDT Sun Apr 20 2025
...New UPDATE...
.KEY MESSAGES...
Issued at 246 PM EDT Sun Apr 20 2025
- A High Risk of rip currents continues at area beaches.
- Sensitive fire weather conditions and little to no precipitation
chances are forecast to persist through this week.
- Warming trend continues, with highs in the 90s across the
interior by mid-week.
&&
.UPDATE...
Issued at 820 PM EDT Sun Apr 20 2025
The forecast for east central Florida remains on track, with no
major adjustments made with the evening update. Conditions are
anticipated to remain dry through the overnight hours as an area
of high pressure remains situated across the western Atlantic
waters. Moisture builds slightly in the low to mid-levels,
allowing for some increasing cloud coverage across the area
overnight. Onshore winds become lighter and less gusty at 5 to 10
mph. Lows remain seasonable for this time of year, falling into
the low to mid 60s across east central Florida.
&&
.PREVIOUS DISCUSSION...
Issued at 246 PM EDT Sun Apr 20 2025
Rest of Today-Tonight...Once again winds were behaving through
the morning update, then started to over perform in the early
afternoon as gusts increased to 25-30 mph across much of East
Central Florida. RAP analysis indicates the likely culprit is
925mb winds a little stronger than previously indicated over
Central Florida mixing down early this afternoon, which may have
knocked dew point temperatures down a degree or two as well. We`ve
probably seen the peak of this enhanced low-level flow, as winds
aloft are expected to decrease as the center of high pressure over
the adjacent Atlantic waters scoots closer, causing surface winds
to decrease back to around previous forecast values by the late
afternoon or evening. Nearly unanimous consensus in model guidance
for this scenario, just a question of precise timing. These
slightly stronger winds and slightly lower humidity values do push
fire weather conditions across the interior right to the edge of
Red Flag criteria, and a few locations could see critical fire
weather conditions for an hour or two. Pushed an early edition of
the afternoon forecast package based on this development and
expected progression.
No significant changes to the rest of the forecast. Can`t rule
out a rogue sprinkle managing to develop over the Atlantic waters
and move onshore, but with areawide PWATs less than 0.75" as
indicated by GOES satellite imagery, rain chances remain as close
to zero as a meteorologist will say. Onshore flow keeps
temperatures along the coast near normal, but subsidence from
high pressure building aloft will help push inland temperatures
above normal. Lows a bit above normal across the board from
continued gentle overnight onshore flow.
Monday-Wednesday...(Modified Previous Discussion) High pressure
remains north of the area through mid-week, though slowly meanders
closer to the Florida peninsula at times. Little change to the
overall pattern, other than an increasingly relaxed pressure
gradient leading to lighter east to southeast winds. Daily sea
breezes will still cause afternoon winds to increase, with gusts
to 15-20 mph along the coast. The fire weather risk will remain
elevated due low humidity and no precipitation forecast. Heat will
also become an increasing concern, as high temperatures reach the
mid-80s along the coast and upper 80s to lower 90s west of I-95
by Wednesday. A few record highs over the interior will be
threatened, particularly on Wednesday. Continued onshore flow will
keep overnight temperatures in the mid-60s.
Thursday-Next Weekend...(Modified Previous Discussion) An upper
level trough weakens the surface ridge by Thursday, though some
form of a ridge axis will continue to remain north of the area
into next weekend. Onshore flow continues, with slightly higher
moisture (PWATs closer to 1") advecting into the peninsula. Rain
chances, though small (~15-20%), initially return to the Treasure
Coast and possibly southern counties by Saturday, then spread
northward across more of the area on Sunday. While this will
likely do little to improve drought conditions or fire weather
concerns, any rainfall is welcome at this point. But, it remains
to be seen whether these PoPs will be realized. Had to blend in
50% previous forecast to avoid significant windshield wiper-ing of
PoPs, so a fair degree of uncertainty in rain chances remains.
Near normal temperatures in the mid-80s along the coast continue,
with above normal temperatures in the upper 80s to lower 90s over
the interior.
&&
.MARINE...
Issued at 246 PM EDT Sun Apr 20 2025
Generally favorable boating conditions, just some lingering
unfavorable conditions offshore of the Treasure Coast this
afternoon as fresh easterly winds finally ease. The ridge axis of
high pressure over the Atlantic waters will remain north of the
area through the week, continuing east to southeast flow. The
pressure gradient finally loosens as the center of high pressure
meanders towards Florida the next couple days, easing winds to
5-15 kts through mid-week. Weak but persistent easterly fetch
holds seas at around 3-5 ft. A more active weather pattern
developing over the CONUS late week should stay north of the area
as high pressure builds into the Atlantic seaboard, but could
cause winds to freshen again. Other than the occasional marine
sprinkle, dry conditions.
&&
.AVIATION...
(00Z TAFs)
Issued at 738 PM EDT Sun Apr 20 2025
Prevailing VFR continues thru the TAF period, with dry and quiet
weather persisting over the next several days. Aviation forecast
continues to simply reflect wind adjustments, with breezy ESE
winds diminishing below 10 knots overnight for interior terminals,
remaining near 10 knots at the coast. Tomorrow, winds shift a bit
more southeasterly and will not be as breezy with the exception of
coastal terminals south of KMLB, where gusts up to 20 knots are
forecast again through the afternoon.
&&
.FIRE WEATHER...
Issued at 246 PM EDT Sun Apr 20 2025
This Afternoon...A few locations across the interior where winds
have been a little higher than expected, up to 15-20 mph with
gusts to 30 mph, and humidity values a little lower than expected,
dropping below 35 pct at times, may briefly reach Red Flag
criteria. However, these conditions are expected to be short
lived, only lasting for an hour or two as most areas should start
to see winds decrease in the next couple hours as upper level
support for enhanced surface winds moves off.
This Week...Very sensitive fire weather conditions persisting into
at least mid-week, as high pressure continues to prevent
precipitation chances. East to southeast flow each day will
enhance in the afternoons as the sea breeze develops along the
coast and moves inland. Winds 10-15 mph and min RH 35-45% over the
interior will lead to near-Red Flag conditions at times. Coastal
areas will see the breeziest conditions, though onshore low will
limit min RH there (45-55%). A warming trend continues through
mid-week, with increasing heat concerns, as highs soar into the
mid-80s along the coast and lower 90s over the interior by Tuesday
and Wednesday. A few record highs will be threatened. Good to Very
Good dispersion each afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 64 83 64 84 / 0 0 0 0
MCO 65 89 65 90 / 0 0 0 0
MLB 68 81 67 82 / 0 0 0 0
VRB 66 82 66 83 / 10 0 0 0
LEE 66 89 66 89 / 0 0 0 0
SFB 64 88 65 88 / 0 0 0 0
ORL 66 88 66 89 / 0 0 0 0
FPR 65 82 66 83 / 10 0 10 0
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
UPDATE...Tollefsen
AVIATION...Schaper
Area Forecast Discussion
National Weather Service San Francisco CA
858 PM PDT Sun Apr 20 2025
...New UPDATE, MARINE...
.SYNOPSIS...
Issued at 1251 AM PDT Sun Apr 20 2025
A slight warming trend will continue through Monday before
cool and cloudy weather returns mid to late week.
&&
.UPDATE...
Issued at 853 PM PDT Sun Apr 20 2025
No updates to the forecast this evening as warmer temperatures
are ready to set in for Monday and Tuesday. Minor HeatRisk will
accompany the brief warmup to start the new work week, before
cooler temperatures arrive for the second half of the week into
next weekend. A slight chance of rain continues for portions of
the North Bay late this week, otherwise expect dry conditions
through the extended forecast.
&&
.SHORT TERM...
(Today and tonight and Monday )
Issued at 228 PM PDT Sun Apr 20 2025
The stratus blanketing the Bay Area and Central Coast has receded
much faster today than it has over the past few days. For
example, stratus did recede from Santa Rosa until after 3PM
yesterday but cleared completely by 1PM today. The 24 hour
temperature change shows temperatures are running on average 5 to
10 degrees warmer today than they were at this time yesterday as a
result of the much more rapid clearing of stratus today. A few
sites across areas of elevated terrain are even running up to 15
degrees warmer today than they were yesterday! That being said, we
did nudge high temperatures across the North Bay Valleys down by
a few degrees (changing the forecast high from the low 70s to the
upper 60s) in order to account for stratus lingering longer across
the NB Valleys than it did across the rest of the region. In
general, temperatures will be fairly seasonal today with highs in
the upper 60s to mid 70s across the interior. Cooler coastal
temperatures prevail with highs in the upper 50s to low 60s.
Temperatures are expected to rise further on Monday as zonal flow
develops with high temperatures in the mid 70s to low 80s across
the interior and low to mid 60s along the coast. Building high
pressure and zonal upper level flow will help to compress the
marine layer to around 500 to 1000 ft overnight tonight. This
should serve to limit inland stratus intrusion overnight and keep
stratus confined more closely to the shoreline/coastal areas.
&&
.LONG TERM...
(Monday night through Saturday)
Issued at 228 PM PDT Sun Apr 20 2025
Zonal flow persists through Tuesday with temperatures remaining
seasonal to slightly above normal in the mid to upper 70s for
interior locations and low to mid 60s along the coast. Heading
into Wednesday, a weak shortwave trough will move in and kick
start a cooling trend across the region. This will allow
temperatures to cool into the upper 60s to low 70s across the
interior and mid 50s to low 60s along the coast. This system is
not expected to produce any precipitation with it but may result
in some locally breezy winds. Current NBM and local high
resolution WRF guidance keep the highest gusts out over the marine
environment but gusts between 20 to 30 mph are possible across
the higher terrain. The cooling trend continues Thursday into the
weekend with high temperatures dropping into the low to mid 60s
across the interior and mid 50s to low 60s along the coast.
Heading into Friday, a deeper upper level trough will move into
the West Coast and bring a low chance for light rain to
northernmost portions of the Sonoma and Napa Counties. At most,
this system looks to bring a few hundredths to a tenth of an inch
to northern Sonoma and Napa Counties with some coastal drizzle
possible further south. Confidence remains low overall that the
North Bay will experience any rainfall from this system due to
guidance continuing to trending rain chances lower and lower
across our CWA and shifting the rain further north. This system
does look as though it will produce breezier conditions across the
region with guidance showing widespread gusts to around 25 to 30
mph and locally stronger gusts across the elevated terrain.
&&
.AVIATION...
(00Z TAFS)
Issued at 657 PM PDT Sun Apr 20 2025
Stratus and fog /MVFR-IFR/ continues along the coast from the Carmel
Highlands to the vicinity of Bodega Bay per satellite imagery. Drier
air flow continues to advect southward over the northern coastal waters
and midway southward along Sonoma County coastline. Recent HRRR output
has followed this pattern fairly closely, showing additional clearing
taking place through the evening to the south of Bodega Bay. Surface
winds are forecast to become weakly cyclonic over the inner waters
tonight and Monday morning, the wind field and radiational cooling
aloft becoming a focus for regrowth of stratus and fog. Onshore winds
will locally bring stratus and fog /MVFR-IFR/ inland. The marine layer
depth has compressed to around 1200 feet per recent profiler data and
spot checking coastal temperatures. A thinner marine layer will help
speed up stratus and fog mix out times Monday morning.
Vicinity of SFO...VFR, then MVFR stratus ceiling forecast 09z early
Monday, mixing out to VFR 17z Monday. West-northwest wind 15 to 25
knots until 04z this evening, decreasing to a light west wind then
shifting to light northeast wind Monday morning. West-northwest wind
resuming Monday afternoon with gusts near 20 knots until early
evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Satellite imagery shows stratus /MVFR-IFR/
filling in across the Monterey Bay. The marine layer depth at the
Fort Ord profiler has recently varied between 1200 and 1400 feet.
HRRR output shows stratus and fog filling into the Salinas Valley
tonight and Monday morning. Stratus and fog /MVFR-IFR/ mix out by
around noon Monday. Onshore winds mainly continuing during the
period between 5 and 15 knots.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 853 PM PDT Sun Apr 20 2025
Breezy to gusty north to northwest winds are building in the
northern waters along with building north swell. Winds look to
increase and spread across the outer waters into the work week.
The gusty occasionally gale force northerly winds in the afternoon
look to become more widespread into the mid week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory until 3 PM PDT Tuesday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Canepa
MARINE...Canepa
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