Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/26/24

Area Forecast Discussion

National Weather Service Marquette MI

 713 PM EDT Fri Oct 25 2024

.KEY MESSAGES...

- Some light lake effect showers are possible over mainly the
  north and east into Saturday morning.

- Precipitation chances return Monday afternoon with normal
  fall temperatures following midweek.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 300 PM EDT Fri Oct 25 2024

A cold front extending southward from low pressure just SE of James
Bay has cleared the UP, but another subtle shortwave embedded amid
broader midlevel troughing is apparent in water vapor imagery and
RAP analyses over the Northern Plains. The UP remains under blustery
NW flow, with winds continuing to gust up to 20-30mph this
afternoon. Meanwhile, lake clouds and spotty shower activity
continue across the eastern UP, but drier lower levels have allowed
for clearing skies across the western and central UP - with just
some diurnal and terrain-driven cumulus cloud streets on visible
satellite.

As the next shortwave drops through, with a reinforcing shot of CAA,
expect an uptick in cloud cover, as well as some additional light
rain showers after 00Z tonight. Lake enhancement is expected across
the eastern UP, but significant rainfall totals are not expected
with only around a 50% chance for totals in excess of 0.10in. Winds
may stay gusty closer to Superior and across the Keweenaw, but
should fall back across the interior UP. Temperatures drop back into
the 30s tonight, but may fall further into the upper 20s in the
interior of the central and western UP under partly cloudy skies.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 302 PM EDT Fri Oct 25 2024

Upper air pattern consists of a broad 500 mb ridge across the
Rockies and a deep trough across the ern U.S. 12z Sat. Ridging
builds into the upper Great Lakes by 12z Mon with troughing on the
west coast. Will hold onto some pops over the east Sat morning
before dry air moves in and shuts off the lake effect Sat afternoon.
Otherwise, did not make too many changes to the going forecast.

In the extended, the GFS and ECMWF show a deep 500 mb trough over
the Rockies 12z Tue with broad ridging in the ern U.S. This pattern
continues into 12z Wed. Troughing then moves into the northern
plains and upper Great Lakes 12z Thu. More troughing then moves into
the Rockies 12z Fri. Manual progs show a sfc front west of the area
12z Tue slowly moving across the area 12z Wed and through the area
12z Thu. Temperatures go from well above normal on Tue and cool to
slightly above normal for Thu and Fri. Will keep pcpn chances in for
Mon afternoon with front nearing the area with pops into Fri with
lake effect pcpn possible on Friday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 713 PM EDT Fri Oct 25 2024

VFR is the primary expected condition in this TAF period, but some
brief MVFR ceilings, as well as some light rain, will be possible at
KCMX early on. Winds to near 30kts from the west to northwest winds
are also expected overnight at KCMX. Elevated winds, albeit lighter
near 20-25kts will continue Saturday at KCMX. Otherwise, expecting
generally light winds at KIWD/KSAW overnight and Saturday.

&&

.MARINE...
Issued at 302 PM EDT Fri Oct 25 2024

Short lived gale with northwest gales to 35 knots will continue into
tonight before the wind dies down. Northwest winds continue 20 to 30
knots on Saturday and 15 to 25 knots on Saturday night. The wind
then stays below 20 knots on Sunday before increasing to 15 to 25
knots Sunday night from the southeast. South winds increase to 30
knots on Monday and Monday night. As a front gets near on Tuesday,
the wind goes below 20 knots through Tuesday night before increasing
behind a front 15 to 25 knots on Wednesday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning until 5 AM EDT Saturday for LSZ243-244-248>251-
     264>267.

Lake Michigan...
None.

&&

$$

SHORT TERM...LC
LONG TERM...07
AVIATION...JTP
MARINE...07




Area Forecast Discussion

National Weather Service San Francisco CA

 800 PM PDT Fri Oct 25 2024

...New UPDATE...

.SYNOPSIS...
Issued at 1208 PM PDT Fri Oct 25 2024

One more day of Summer before Fall arrives in full force on
Sunday. A cold front will bring some light rain Sunday, with
cool, humid and windy conditions persisting through next week.

&&

.UPDATE...
Issued at 744 PM PDT Fri Oct 25 2024

The forecast remains on track this evening with no changes
necessary at this time. The return of onshore flow this afternoon has
helped to increase relative humidity, thus lowering fire weather
concerns. If you are still in a summer mood, time is running out
for a guaranteed beach day so you may want to cash in on that
tomorrow, your winter self will thank you. If you are more in a
fall mood, tomorrow would be a great day to clean out gutters and
take the fall/winter wardrobe out of storage ahead of cooler and
wetter conditions Sunday.

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 1208 PM PDT Fri Oct 25 2024

Winds have finally began to shift onshore this afternoon, but
that`s partly driven by diurnal effects. The SFO-WMC pressure
gradient is decreasing, but at -6.7 mb, it is holding on longer
than the NBM expected. While the winds are light as expected, the
RH was much lower than forecast. For example, the Santa Cruz
mountains were below 30% RH this morning before the sun came up.
Our forecast was closer to 60% at that time. That`s a big miss.
Some significant changes were made to the T, Td, and RH forecast
for the next 24 hours, with a heavy reliance on the high
resolution HRRR guidance, which had a good handle on the dry start
to the day. As expected, the humidity is actually increasing
through the day as onshore winds allow the Td to increase along
with the T. This more humid air, combined with the increasing mid-
level cloud cover, are the first signs of the seasonal change
coming this weekend. Saturday will be another day of warning
signs, with cloud cover continuing to increase under a deepening
marine layer, but the real change comes on Sunday.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 1208 PM PDT Fri Oct 25 2024

The strongest cold front since Spring will move through on Sunday.
This will bring some rain to the majority of the area. As normal,
the North Bay will see the most accumulation, with the amount
quickly decreasing with latitude. Santa Rosa has a 60% chance of
exceeding 1/10", and 40% chance of exceeding 1/4". San Francisco
has a 40% chance for 1/10" and a 20% chance for 1/4". San Jose has
a 15% chance of exceeding 1/10" and a 5% chance of exceeding
1/4". That being said, everywhere north of Santa Cruz has a better
chance than not of seeing some rain on Sunday, and many areas
will have the wettest day since May.

This front will bring more than rain. It`s a virtual certainty
that much colder air will move in and bring temperatures we also
haven`t seen since May. The 850 mb temperature was last measured
by the morning balloon launch at 18.75C (65.8F). The ECMWF
ensemble shows a 90% certainty that the 850 temp will drop below
5C (41F) by Monday. That`s significant. Most areas will be
roughly 10 degrees cooler than they were this week. There is still
some uncertainty regarding how cold it will be. Some of our bias-
corrected guidance is actually working against us. The reason for
this is that most of October has seen temperatures higher than
expected. These models recognize their low bias and correct
upwards. That`s typically a great thing, but since we are
switching from an offshore regime to onshore winds, the same bias
likely does not apply. Weather models without a memory of their
previous errors are much colder, and we utilized the 50th
percentile of the NBM ensemble for max temperatures, rather than
the deterministic NBM. These colder temperatures will also
increase the humidity next week. Stronger winds will follow the
cold front, and there is a 50% chance of 30 mph winds along the
coast on Monday. Cool, humid air will continue through next week,
although the winds will calm a bit beyond Tuesday. There is
another, weaker system that moves through on Thursday or so, which
currently only looks to bring very light rain to the North Bay.
Bottom line, it may be time to dust off your furnace this weekend.

&&

.AVIATION...
(00Z TAFS)
Issued at 424 PM PDT Fri Oct 25 2024

High confidence that VFR will prevail through the TAF period. Expect
moderate to breezy conditions to continue into early evening,
before transitioning into light and variable overnight. As the
next system moves over our area, winds will begin to build and
become westerly and breezy/gusty by Saturday afternoon. This will
also bring some lower CIGs by Saturday night.

Vicinity of SFO...High confidence VFR through the TAF period.
Onshore breezy winds will diminish overnight and become light and
variable. Onshore breezy and gusty winds return by Saturday
afternoon. Ceilings start to develop Saturday night, but will remain
VFR for the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...High confidence VFR through the TAF period.
Winds will turn to variable and light overnight with a potential
S/SE component overnight. Onshore winds return by late Saturday
morning.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 424 PM PDT Fri Oct 25 2024

Moderate to breezy winds continue over the waters into the
weekend. Expect moderate wave heights to persist through much of
the weekend before an upper trough moves onshore across the
Pacific Northwest on Sunday. Wave heights will increase in
response to gusty northerly winds building into the area, with
significant wave heights of 10-12 feet expected in the outer
waters by Monday.

&&

.FIRE WEATHER...
Issued at 449 AM PDT Fri Oct 25 2024

Offshore flow will continue to weaken through the remainder of
Friday morning before gradually transitioning to onshore flow by
this afternoon. Current overnight humidity recoveries remain poor
above 1,000 feet with most sites reporting humidities between 25 to
40% while locally drier conditions persist at higher elevations.
Guidance from the HRRR and NAM indicates that the KSFO-KWMC pressure
gradient will transition from negative (offshore) to positive
(onshore) by late this morning/early this afternoon. The KSFO-KWMC
pressure gradient has continued to weaken with a pressure difference
of -8.20 mb reported at 4AM compared to -8.90 mb at 2AM. While the
winds have begun to weaken, elevated fire weather concerns will
linger through Friday evening as drier conditions persist through
the remainder of the day. Fire weather concerns will then decrease
heading into the weekend as an approaching upper level system brings
moister air, improving both nighttime and daytime humidities, and
elevated potential for light wetting rains to the North Bay.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...SO
MARINE...Murdock

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Area Forecast Discussion

National Weather Service Raleigh NC

 848 PM EDT Fri Oct 25 2024

.SYNOPSIS...
High pressure will shift off the Southeast coast through tonight. A
cold front will move southeast across the Carolinas late Saturday.
Cool high pressure will build into the area from the north starting
Saturday night, then hold over the Eastern United States through
early next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 848 PM Friday...

The sfc high has shifted offshore this evening promoting continued
light sswly flow across our area.  Aloft, a shortwave entering the
western slopes of the southern Appalachians continues to generate
light precipitation over KY/WV.  While this wave will pivot overhead
tonight, any associated rain should get squeezed out over the
mountains and keep central NC dry.  However, some associated cloud
cover will move across our area. This, in combination with higher
dew points compared to last night, and some stirring of sly sfc
winds should promote mild overnight lows in the upper 40s to lower
50s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
As of 255 PM Friday...

* An uptick in chances of a few showers Saturday afternoon and
  especially Saturday evening, focused across the south.

A cold front will shift southeast across central NC on Saturday,
reaching the Triad during the late morning, the Triangle around
midday and southern areas including Wadesboro and Fayetteville in
the late afternoon. Some enhanced moisture is attendant to the front
with PW values increasing to 1.0 to 1.25 inches across central NC as
the front moves across the area. NWP guidance and CAMS have
highlighted an uptick in PoPs across the area with the HRRR and
NAMnest being most aggressive in rain chances. Even the MET/MAV
guidance provides 39/51 PoPs respectively for Saturday night. While
the prolonged period of dry weather suggests not to get too excited
about rain chances, the trend in the guidance can`t be ignored and
we`ve upped PoPs for late Saturday afternoon and Saturday night as
the front drifts south and a little return flow back over the front
may enhance the development of showers into the evening hours.
Rainfall amounts will be very light, likely on the order of a few
hundredths and have not included any mention of thunderstorms. Even
though confidence in the coverage of showers is still limited,
confidence is higher that a fair amount of at least mid-level
cloudiness will develop resulting in the most clouds we`ve seen over
the past few weeks. Warn advection ahead of the front will result in
highs in the upper 70s near the VA border to the lower 80s in most
locations with a few mid 80s across the south near Fayetteville and
Wadesboro. Colder air will push into the area on Saturday night with
lows in the mid 40s near the VA border to the lower 50s across the
south.  -Blaes

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 200 PM Friday...

* A brief stint of below-normal temperatures early next week
 with a risk for patchy light frost across northern NC Sunday
 night...

* Well-above normal temperatures return mid/late week...

* Rain chances remain meager...

In the wake of Saturday`s cold frontal passage and underneath broad
upper troughing, a series of +1030 mb surface highs building and
merging over the Eastern US will support a brief stint of below
normal temperatures early next week. Sunday/Sunday night will be the
coolest 24 hour period, highlighted with a risk for patchy light
frost Sunday night, mainly in outlying areas across the northern
portions of the piedmont and coastal plain, where the 13z/25 NBM run
indicates 30-60% prob. of temps 36 degrees or colder.

Temperatures will quickly moderate as an expansive/strong upper
level ridge builds into the Eastern US from Tuesday onward, leading
to a return to warm, well-above normal temperatures. Daytime highs
in the upper 70s to lower 80s to close out the work week(10 to 15
degrees above normal).

Latest model trends suggest another mostly dry frontal passage late
Friday with very limited moisture and lift across the region as the
front advances SEwd through the Carolinas.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 730 PM Friday...

VFR conditions are expected to hold across central NC through Sat,
although we will see periods of clouds based around 10-13 thsd ft
AGL passing over the area tonight, followed by another round of VFR
clouds based at 5-8 thsd ft AGL Sat, mainly Sat afternoon/evening.
These clouds will be associated with an upper level disturbance and
surface cold front that will push southeastward through central NC
Sat. This will cause light surface winds from the SW tonight into
Sat morning to veer around to blow from the NW and NNW at 10 kt or
less for the Sat afternoon/evening hours. A few brief sprinkles or
light showers are possible Sat, esp across the S late in the TAF
period, but the risk and confidence in timing is too low to include
in the TAFs for now.

Looking beyond 00z Sat, surface winds will continue to shift to be
from the NE and may gust up to 15-20 kts Sat evening/night into Sun
morning as cooler air surges into the area from the N. Additionally,
behind the front, stratocu clouds are likely to hover in the lower
reaches of VFR Sat evening through Sun, and may drop to near MVFR
threshold Sun morning. Isolated patches of light rain are also
possible early Sun over southern sections. Overall, though, VFR
conditions will dominate through the middle of next week. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Luchetti
SHORT TERM...Blaes
LONG TERM...CBL
AVIATION...Hartfield