Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/28/24
AREA FORECAST DISCUSSION
National Weather Service Albany NY
944 PM EST Fri Dec 27 2024
.SYNOPSIS...
An approaching warm front will bring some intermittent
periods of light freezing rain and plain rain late tonight into
Saturday afternoon as temperatures slowly rise to or above freezing.
Milder weather returns Sunday and Monday as another storm system
brings a widespread rainfall, which may result in localized poor
drainage flooding. Confidence is increasing for another system to
bring a mix of rain and snow around New Year`s Day.
&&
.NEAR TERM /THROUGH SATURDAY/...
Key Message:
- A weak warm front will bring intermittent periods of freezing
rain overnight into Saturday which could lead to locally
slippery travel.
Discussion:
UPDATE as of 943 pm EST... Mid and high clouds continue to
increase ahead of a weak thermal trough, as high pressure slowly
drifts east from southern Quebec to northern Maine. We
continued to increase the clouds prior to the light pcpn onset.
Temps have not dropped off as much with the cloud cover, as the
NYS Mesonet and western New England obs are mainly in the upper
teens and 20s. Some mid and upper 30s are over the eastern
Catskills (Tannersville 38F) and Taconics (Copake 36F). We tried
to bring in the light freezing rain for the eastern Catskills,
mid Hudson Valley, southern Taconics, and southwest New England
between 1 am and 4 am, as the weak isentropic lift increases.
The 00Z 3-km HRRR is more aggressive than the 00Z 3-km NAMnest
with the onset and coverage. However, the spotty freezing rain
and plain rain should be more widespread from the Mohawk River
Valley, Capital Region and Berkshires southward between 3 am
and 7 am. The Winter Weather Advisory looks good. Lows will
generally be in the upper teens to upper 20s (a few warmer
readings over the higher terrain) and then slightly rise toward
daybreak.
PREV DISCUSSION [0339 pm EST]...
Intermittent periods of rain and freezing rain will begin
before daybreak, mainly for areas south of Albany, before
lifting northward during Saturday morning. Much of the
precipitation departs the region by later Saturday afternoon.
Overall QPF amounts do not look particularly high (generally up
to one tenth of an inch for most areas except up to 0.25 inches
across the mid- Hudson Valley into the Litchfield Hills). This
will limit ice accumulation to up to one tenth of an inch with
most areas just receiving a very light glaze. Still, the very
cold ground surfaces can allow rain to freeze on any untreated
or elevated surfaces. Even once air temperatures rise above
freezing (33 or 34 degrees), rain can continue to freeze on
surfaces until ground temperatures warm enough to prevent any
additional icing. Will continue with the Winter Weather Advisory
for all of eastern New York and western New England given the
spotty nature of ice accumulation and potential impacts. While
temperatures in most areas will rise into the upper 30s to
mid-40s by Saturday afternoon, some sheltered areas in the
Mohawk Valley into the Upper Hudson region may still be around
freezing into Saturday evening. As a result, the Winter Weather
Advisory for the Mohawk Valley was extended until 5 PM Saturday.
Patchy fog will likely develop by Saturday afternoon as milder
air moves over the very cold ground and snowpack.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Key Message:
- A soaking rainfall is expected Sunday into Monday which will
lead to river rises and the potential for some localized
flooding. There remains a marginal risk for excessive rainfall
during this time.
Discussion:
A break in the precipitation will occur Saturday night for most
areas, though some patchy fog and even drizzle may occur through
the night. Temperatures Saturday night will hold fairly steady
in the 30s with some localized areas within the Lake
George/Saratoga region possibly hovering right around freezing.
The next negatively-tilted upper shortwave and surface low
pressure system arrives on Sunday, continuing into Monday.
Surface temperatures will continue to warm into the 40s and 50s
allowing for this system to bring all rainfall. One round of
rainfall will occur on Sunday lifting from south to north along
another warm front. The second round of precipitation then
moves through Sunday night into Monday morning along the cold
front. Periods of moderate to locally heavy rainfall will be
possible Sunday night into Monday morning. Overall QPF amounts
of 0.75 to 1.50 inches are expected across the region with some
locally higher amounts across the eastern Catskills due to
upslope enhancement. The milder conditions, rain and snowmelt
will result in river rises and may result in localized flooding
(see Hydrology section for details).
Rain is expected to linger into early Monday before the cold
front passes allowing rain to transition to scattered showers.
Cooler air advances in by Monday afternoon leading to falling
temperatures. This may allow for some snowflakes to mix in
across the Adirondacks.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Key Messages:
- Mild conditions on Tuesday followed by a trend towards more
wintry weather.
- A storm system looks to bring snow to at least the higher
terrain Wednesday, followed by additional lake effect snow
showers Thursday and Friday.
Discussion:
A weak ridge of high pressure will bring fair and mild weather
on Tuesday.
The next system is expected to impact the region for Tuesday
night into Wednesday. Initially, this will be another milder
system heading into the area from the west, but the deepening
upper wave generates its own cold air and temperatures cool
gradually aloft as the surface wave deepens along the New
England coast. Probabilistic guidance shows the best chance for
any accumulating snow would be across the southern Adirondacks
and southern Green Mountains.
As the system departs, colder air will work its way into the
region on northwest winds. Some lake effect snow showers should
start to develop in the storm`s wake for Wednesday night into
Thursday, especially for western and northern areas. It will
become breezy Thursday and Friday behind the deepening low over
eastern Canada, and with temperatures near normal to slightly
below, it looks blustery and cold. Lake effect snow showers are
expected to continue Thursday and Friday over western areas.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
High pressure will move eastward from southern Quebec over
northern New England. A weak disturbance and a warm front will
increase clouds early tonight with clouds thickening and
lowering. VFR conditions will diminish after 06Z/SAT with some
light freezing rain breaking out from south to north across the
terminal sites. PROB30 or TEMPO groups were used to bring the
light freezing rain initially at KPOU 06Z-09Z/SAT, 09Z-12Z/SAT
at KALB/KPSF...and 11Z-15Z/SAT for KGFL. The intermittent light
freezing rain will gradually transition to plain rain about
12Z/SAT, KALB/KPSF 16Z/SAT and KGFL 19Z/SAT. KGFL may remain
light freezing rain before it diminishes in the early pm. The
pcpn will be light and spotty, as temps gradually rise above
freezing.
Cigs/Vsbys will lower to MVFR levels 09Z-13Z/SAT and will
continue to lower to IFR levels in the late morning/early
afternoon. Widespread low MVFR/IFR cigs will continue in the
afternoon with spotty drizzle. Vsbys will hover in the MVFR
range.
The winds will calm or light and variable direction at 4 KT or
less tonight. They will light from the south/southeast mainly at
5 KT or less, except at KALB they may increase to the 10 KT by
the late morning/early pm. LLWS was added to KPOU/KPSF after
12Z/SAT as the the 2 kft AGL winds increase to 30-35 KT with
the sfc winds generally 5 KT or less. The LLWS should diminish
towards nightfall.
Outlook...
Saturday Night: No Operational Impact. Patchy FG.
Sunday: High Operational Impact. Definite RA.
Sunday Night: High Operational Impact. Breezy. Definite RA.
Monday: High Operational Impact. Definite SHRA...RA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: High Operational Impact. Definite SHRA.
New Years Day: High Operational Impact. Definite SHRA.
&&
.HYDROLOGY...
A period of moderate to locally heavy rain is expected Sunday
into Monday morning. With a frozen ground in place in many
areas, along with some snowmelt, runoff will be enhanced and
might lead to some localized flooding. River rises are expected
but no flooding is expected at this time. While ice has
developed on area rivers, the overall depth is limited to mainly
3 to 6 inches (estimated). This shallow depth should limit the
potential for ice jam development but could occur in any areas
where obstructions block the flow of ice. Trends will continue
to be monitored for any possible localized flooding or ice jams.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for
CTZ001-013.
NY...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for
NYZ047-051>054-058>061-063>066.
Winter Weather Advisory from 5 AM to 5 PM EST Saturday for
NYZ032-033-038>043-048>050-082>084.
MA...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for
MAZ001-025.
VT...Winter Weather Advisory from 5 AM to 5 PM EST Saturday for
VTZ013>015.
&&
$$
SYNOPSIS...Rathbun/Wasula
NEAR TERM...Rathbun/Wasula
SHORT TERM...Rathbun
LONG TERM...SND
AVIATION...Wasula
HYDROLOGY...KL/Rathbun
Area Forecast Discussion
National Weather Service La Crosse WI
526 PM CST Fri Dec 27 2024
.KEY MESSAGES...
- Widespread rainfall continues moving northward this afternoon
into Saturday. Storm total amounts of 3/4" to 1" are
expected.
- Above normal temperatures tonight into Monday with highs in
the 40s and lows in the 30s. Record warm low temperatures at
Rochester and La Crosse are possible tonight.
- Precipitation chances continue Monday afternoon into Tuesday
with more seasonable temperatures by the middle of next week.
Lesser chances for precipitation on Sunday.
&&
.DISCUSSION...
Issued at 243 PM CST Fri Dec 27 2024
Widespread Rainfall This Afternoon Into Saturday
After fighting with some drier low to mid level air over much
of the area earlier today, northward moisture advection
associated with a 500hPa and associated surface wave has
sufficiently saturated the column across northeast Iowa this
afternoon, allowing rainfall to begin. The moisture advection
and subsequent rainfall will continue northward through the
evening and into Saturday as the wave propagates northward
through the area. Various bits of 900-600hPa frontogenesis move
through the area this evening as seen in the RAP which combined
with lift from the low should provide enough upward motion for
some moderate rainfall rates across the area. The 27.12z HREF
currently paints 40-80% probabilities for rates above 0.1 inch
per hour but these probabilities fall off dramatically at and
above 0.15 inches per hour, down to 0-20%. With PWATs still in
the 99th percentile or above as compared to climatology,
widespread QPF values of 3/4" to 1" continue to be expected.
With the higher rainfall amounts and ever eroding snowpack, the
concern for ice jams continues into Saturday for local rivers
with the runoff, especially those further north. Will continue
to monitor for impacts that develop, if any.
Models continue introducing below freezing temperatures above
1.5kft north of I-94 Saturday morning as the low moves northward
and exits the region, suggesting some snowflakes could mix in
with the rain across these areas. This is dependent on how low
the freezing level is able to get, but 27.12z HREF soundings
show minimal spread amongst the members in the temperature
profile and indicate good agreement that the freezing level
should be 1.5kft or less. Still not expecting any snow
accumulations if any snow does fall given warm surface
temperatures.
Above Normal Temperatures Tonight Into Monday
Continue to expect above normal temperatures tonight into the
weekend. Overnight lows are expected to be in the mid to upper
30s, 25-30F above climatology for this time of year. These
current forecast lows remain at or above the current record
warm low temperature for both La Crosse and Rochester.
Dry air an subsidence moving into the region on the backside of our
passing wave should allow for some clearing of our recently very
cloudy skies Saturday afternoon, especially west of the
Mississippi River. Depending on how much skies are able to
clear, could see some additional warming Saturday afternoon.
Have trended high temperatures towards the 75th percentile of
the NBM for Saturday afternoon to account for the expected
clearing, resulting in high temperatures into the mid 40s.
Precipitation Chances Monday Afternoon into Tuesday and Lesser
Chances Sunday
Clouds look to fill back in as we head into Sunday as a 500hPa
trough and associated surface wave move northeastward out of
Texas. These features look to mainly stay to our south and east,
but could still see a glancing blow of rain in far southwest
Wisconsin. There has also been some indication in the
deterministic models and the GEFS that rain could develop in
our far west Sunday afternoon as well as this system moves
through the area (0%-15%) associated with isentropic ascent on
the 290-300K surface and weak frontogenesis at 925hPa during
this time period. However, have tended towards a drier solution
at this time due to poor agreement amongst various model
solutions and an overall lack of indication in ensemble
guidance.
The NBM continues pulling the low pressure system expected to
develop across the Great Plains Monday further south run to
run. However, looking at the 27.00z LREF members, there is
still plenty of discrepancy regarding location of the highest
precipitation chances. In the NBM, precipitation chances remain
30-50% south of I-90, which has been a consistent signal over
the last several days, suggesting that we should see some sort
of precipitation, but how much precipitation our area sees will
depend on if the NBM continues to take a more southerly track
similar to the GEFS/GEPS (lower precipitation chances:
20-40%) or a more northerly track similar to the ENS (higher
precipitation chances: 40-60%). Regarding precipitation type, it
continues to look as though precipitation will initially fall as
rain before northwest winds begin to usher cold air into the
column, allowing for a transition to a rain/snow mix before
ultimately transitioning to all snow on the backside of the low.
Temperatures become more seasonable by mid next week owing to
the cold air advection behind the low with highs in the 20s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 526 PM CST Fri Dec 27 2024
Widespread rain continues through the overnight. Areas of fog
will be possible overnight as visibilities are expected to
range from 0.5SM to 3SM. CIGS will also remain low with cloud
bases ranging from 200ft to 1000ft. Precipitation is expected
to leave the area by mid-morning Saturday. There is a low chance
(20 to 40%) of some snow mixing in with the rain in north
central Wisconsin Saturday morning. Even with the precipitation
ending, there will be enough low-level moisture around that the
lowered CIGS and visibilities could hang around into the
early afternoon. By mid-afternoon, trends are pointing towards a
break in the thick cloud cover before returning Saturday
evening.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Falkinham
AVIATION...Cecava
Area Forecast Discussion
National Weather Service Sioux Falls SD
447 PM CST Fri Dec 27 2024
.KEY MESSAGES...
- Fog continues to linger into the evening east of I-29.
However, concern for fog expansion after sunset continues to
grow. Additional dense fog may be possible with new advisories
needed.
- Well above normal temperatures expected Saturday and Sunday.
Highs in the 40s both days.
- Very light precip may fall Sunday morning east of I-29. Any
impacts would remain minimal, but precipitation chances may
increase in the future.
- Impactful storm still on track for Monday into Monday night.
Probabilities of >0.25" of QPF continue to trend towards 100%.
Uncertainty on rain to snow transition is impacting overall
snow potential but plan on light snow accumulations. Best
advice is to prepare for some impact despite uncertainty.
- High confidence in a downward temperature trend through the
rest of the week. Below zero temperature probabilities grow to
20-30% by the end of next week.
&&
.DISCUSSION...
Issued at 225 PM CST Fri Dec 27 2024
THIS AFTERNOON: Fog and stratus continues to linger in areas of the
higher elevations in Minnesota and Iowa. Further west however, with
the arrival of a warmer southwest wind, highs have surged deep into
the 40s. Anticipating some continued improvement in visibilities
this afternoon, but if we can`t clear out fog/stratus by sunset, it
won`t take long to settled back downward.
TONIGHT: Winds should settle quickly after sunset allowing potential
for lingering low stratus to again settled downward. In addition,
if we can clear some of the high level stratus, then additional
radiation fog may develop along the I-29 corridor later this
evening. NBM visibility probs are once again too low given the
setup, with HREF probabilities of less than 0.5" exceeding 80%
again over NW Iowa into SW Minnesota into Saturday morning.
Would like to see if cirrus can clear to aid in radiational
cooling potential before issuing a dense fog advisory, but one
is certainly possible.
SATURDAY: With an increase in westerly wind Saturday, we may be
able to scour out fog a bit faster than on Friday. Looking aloft,
we`re continuing to see increasing low-lvl warm advection sliding
through the Plains, pushing 850mb temperatures into the +6C range by
Saturday morning. If we`re not dealing with lingering low clouds,
then see now reason why temperature won`t again surge into the upper
40s to 50. Have followed the warmer RAP for temperatures tomorrow
which sit around the 90th percentile of the NBM, but notably is
still not the warmest guidance available.
SUNDAY: Mid-lvl troughing, and left exit of an upper jet, moves
through Saturday night into Sunday from west to east. While
soundings show decent lift within a deep saturated layer above 700
mb, they also show a fairly stout dry layer below 700 mb. The NAM,
perhaps with its boundary layer moisture bias, suggests QPF reaching
the ground by daybreak Sunday along and east of I-29. If this
seeder-feeder process can`t come to fruition, then precipitation
would have a deep dry layer to make it through. Nevertheless, PoPs
may need to be increased in the future. Temperatures on Sunday again
climb into the 40s in most areas.
MONDAY: The most impactful weather of the next week will take place
on Monday. A fairly progressive mid-lvl trough drops from the
Northern Rockies and into the Plains by daybreak. Moderate to
strong gradually sloped mid-lvl frontogenesis will develop ahead of
this wave. Soundings continue to show potential that most of the
initial precipitation will occur as liquid with wet-bulb
temperatures below 1200 ft still above freezing and surface
temps near 32-37F. If overnight lows can drop a bit further into
the 20s, then some very light icing could take place during the
initial developing stages of precipitation prior to daybreak.
However, wherever the initial band does form, precipitation
rates have the potential to overwhelm this warm layer and you
could begin to see a transition to snow at slightly warmer
surface temperatures. Eventually the frontal forcing weakens by
early afternoon Monday, replaced with a compact deformation zone
that slides through the Missouri River Valley into the evening
and overnight hours. Ensembles continue to show high
probabilities (80%+) of 0.10"-0.25" of QPF with this system,
with most of the variation in location due to positioning of the
initial frontal band. The one thing that is a bit more apparent
today is the slightly southward shift in the ECE as compared to
the CME/GEFS. All-in- all, if rain can turn to snow in a more
efficient manner, then general potential for a fairly large area
of 1-3" of snow seems reasonable, with some potential for
upwards of 4-5" in south central SD by time snow ends late
Monday evening.
TUESDAY-FRIDAY: Medium range models continue to come into good
agreement that we`ll see a high amplitude ridge form over the
Rockies by the middle to end of next week. This sharp north to
northwestward turn in low-lvl flow will bring colder Canadian air
southward, resulting in the drop of temperatures below normal
for the first couple weeks of January. In fact, probabilities
for low temperatures falling near or below 0 rise towards the
20-30% range by next Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 445 PM CST Fri Dec 27 2024
Winds will be light overnight, and fog is again to expand across
areas from the Interstate 29 corridor and eastward during the
night, and some of this fog may be dense. To the west of this
area, fog will still be possible, though probabilities are
lower. Fog is then expected to slowly dissipate by late Saturday
morning.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...Dux
AVIATION...JM
Area Forecast Discussion
National Weather Service Memphis TN
555 PM CST Fri Dec 27 2024
...New AVIATION...
.SYNOPSIS...
Issued at 246 PM CST Fri Dec 27 2024
A dry and warm day is in store to kick off the weekend. Strong to
severe thunderstorms are possible Saturday afternoon into the
evening hours. As this system exits, a dry start to the work week
before yet another system brings a cool down to the area late
week.
&&
.DISCUSSION...
(This evening through next Thursday)
Issued at 246 PM CST Fri Dec 27 2024
Shortwave ridging across the region has allowed mostly dry
conditions across the area today. A dry slot depicted on satellite
has allowed for some sunshine to poke through and allowed for
temperatures to hang steady in the upper 50s and lower 60s.
Confidence continues to increase for severe weather potential as a
negatively tilted trough crosses the area on Saturday. Long term
guidance hinted earlier at a weak perturbation ahead of the system
bringing stratiform rain to the area, which would decrease the
severe weather threat. Unfortunately, short term guidance is not
showing much in the way. The severe weather threat remains
conditional as instability is still the limiting factor.
The LLJ will rapidly amplify mid-level flow which will provide
plentiful bulk shear (50-60 kts) across the area, which also
increases storm relative helicity. The amount of instability will
come down to where the warm sector resides and if any cloud breaks
allow sunshine to poke through. Several CAMS show a swath of CAPE
between 500-700 J/kg from Clarksdale, Oxford, Tupelo and southward
towards central Mississippi. Model soundings do still show a weak
cap in the very early morning hours, but is quickly overturned as
the warm sector and Gulf moisture approach the area. From the
NBM, probabilities for SBCAPE exceeding 500 J/kg are less than
50%. The system now looks to approach from the MS Delta in the
late morning into early afternoon and exit the CWA before
midnight. Damaging winds and a few tornadoes are the primary
concern, with heavy rainfall and large hail also possible.
While the severe weather chances still remain favorable but awaiting
limiting factor results, precipitable water values remain in the
90th percentile for this time of year (around 1.25"). The
Mississippi Delta region received almost 2" of rain with rainfall
from last night, with another 1-2" expected with this robust
convection. Training of storms is also likely bringing rainfall
totals to 1-3" along and south of I-40 with lesser amounts to the
north. Be cautious of any elevated streams, rivers, and any urban
areas that pond water easily.
On the bright side, after the system exits east late tomorrow night,
a brief lull in precipitation will arrive with moderate
temperatures. The warmer temperatures will continue, but a
disturbance on track to middle TN could bring a stray shower Monday
night. A deep Pacific trough will move across the region on Tuesday.
This cold front will bring much cooler (with morning lows near
freezing) and seasonable weather.
DNM
&&
.AVIATION...
(00Z TAFS)
Issued at 555 PM CST Fri Dec 27 2024
Messy TAFs remain this issuance. Confidence in fog potential
continues to grow across all TAF sites along a decent inversion
amongst already saturated soils from this morning`s rainfall.
HRRR is pretty aggressive with how low visibilities fall, though
this solution can not be ruled out. Ceilings lower to IFR
conditions around 06Z across the airspace, lowering to LIFR
conditions by 09Z. By daybreak, ceilings briefly improve to MVFR
conditions as wind speed increase to around 6-8 kts. A cold front
will bring increased shower and thunderstorm activity tomorrow
afternoon and into evening impacting each terminal with its
movement. LLWS is expected to impact MEM beginning around 02Z
tomorrow with the movement of a quick moving jet.
AEH
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...DNM
AVIATION...AEH
Area Forecast Discussion
National Weather Service Melbourne FL
701 PM EST Fri Dec 27 2024
...New KEY MESSAGES, UPDATE, AVIATION...
.KEY MESSAGES...
Issued at 701 PM EST Fri Dec 27 2024
- There is a limited risk for excessive rainfall along the
immediate Treasure Coast this evening. Patchy fog is possible
overnight, especially north of Orlando.
- Seasonably warm with scattered showers again on Saturday.
Showers likely with isolated lightning storms Sunday afternoon
into early Monday, ahead of a weakening cold front .
- Poor to hazardous boating conditions continue through the
weekend.
- Mostly dry and pleasant for New Year`s Eve. Turning cooler to
start the new year.
&&
.UPDATE...
Issued at 701 PM EST Fri Dec 27 2024
Rich subtropical moisture remains overhead this evening.
Satellite-estimated PW values exceed 1.5", which lies between the
90th percentile and max moving climatological average. Combined
with the onshore flow and a pesky inverted trough, we have seen
training areas of moderate to heavy rain on the immediate Treasure
Coast this evening. This has prompted a Flood Advisory near
Stuart where localized 3" tallies have been reported along with
some standing water. Hi-res guidance is not handling this all that
well, with the HRRR likely performing the best. It indicates a
lessening trend with this rain later tonight as slightly drier air
briefly advects onshore. However, another surge of moisture may
work northward from SoFlo toward daybreak, reintroducing showers
to our Treasure Coast communities. This is a low confidence
forecast, but one with potential impacts as reasonable worst-case
rainfall off today`s HREF members exceed 4-6" over our southern
communities through Saturday evening. Most areas will receive far
less than this, but it underscores a localized threat for
excessive rainfall.
Elsewhere tonight, expect lighter showers to lessen in coverage with
mostly cloudy skies. One area where skies may clear, or stratus
lowers toward the surface, would be west of I-4 where we have added
the mention for patchy fog overnight. With all this moisture in
place, temps won`t fall too much, mainly into the mid 60s.
&&
.PREVIOUS DISCUSSION...
Issued at 300 PM EST Fri Dec 27 2024
Now-Tonight...18z RAP analysis indicates a weakened surface
trough extending from east-central Florida northward to just off
of the Carolina coast. Clouds have thinned enough to let some
sunshine through this afternoon, with temperatures responding by
climbing into the 70s in most spots. The cooler exception is the
immediate Volusia coast where temps remain in the upper 60s.
Isolated to scattered showers continue along the coast, and some
additional development is now ongoing across inland Indian River,
St. Lucie, and Martin counties. The general trend will be for
decreasing rain chances overnight but still kept a 15-20 percent
chance along the coast as showers offshore move northwestward.
Lows fall into the 60s early Saturday morning, staying a few
degrees warmer along the marine-land interface.
Saturday-Sunday...Hi-res models indicate locally higher precip
accumulation potential along the Treasure Coast Saturday morning,
up to 0.75", with low-level flow favorable for repeated rains
over the same locations. Forcing looks to be more modest on
Saturday, but continued isolated to scattered showers are forecast
to stream onshore from time to time. Afternoon temperatures peak a
degree or so higher Saturday as a little less cloud cover is
forecast. By Sunday, a cold front is forecast to approach the
Florida panhandle as moisture increases out ahead of it. Surface
winds increase out of the south 10-15 mph with gusts up to 20 mph.
With daytime heating, the environment will become supportive of
scattered showers and at least marginally supportive of isolated
lightning storms. Modeled lapse rates are meager, so maintaining
any storm`s strength may be a challenge. The best chance at a
stronger storm will be near Lake George and northward, otherwise
outside of our forecast area.
Monday-Thursday (modified previous)...Behind Sunday`s front,
zonal flow aloft sets up, keeping conditions relatively mild
locally. Rain chances are forecast to remain below 20 percent
across the peninsula from early next week into the middle of next
week, with isolated shower development across the local Atlantic
waters possible. Another front (or two) moves toward the
peninsula around New Year`s Day, though current guidance is
hinting that it will pass with very little fanfare as a result of
limited moisture availability.
The early week frontal passage will do little to help with
temperatures, with highs remaining in the 70s Monday and in the
upper 70s to low 80s on Tuesday. Lows generally in the mid 50s to
low 60s. The second frontal passage, however, looks as though it
could cool east central Florida off more significantly, with
highs on Wednesday in the 70s and falling into the mid 60s to low
70s on Thursday. Lows are forecast to fall into the upper 40s to
mid 50s Wednesday night, with the coolest night during the
forecast period on Thursday, with lows in the 40s across all of
east central Florida.
&&
.MARINE...
Issued at 300 PM EST Fri Dec 27 2024
Recent observations this afternoon from Buoy 41009 indicate waves
around 6 to 7 feet with light and variable winds. A Small Craft
Advisory remains in effect for the offshore Volusia and Brevard
waters, where seas of 5 to 7 feet are expected through this
evening. Elsewhere, small craft should exercise caution. Scattered
showers, some heavy at times, are forecast to continue.
Southeast winds Saturday veer southerly on Sunday ahead of an
approaching, weakening cold front. After a brief period of light
and variable wind on Monday, a southwest breeze of 10 to 15 knots
returns on Tuesday ahead of a stronger set of reinforcing cold
fronts mid week.
&&
.AVIATION...
(00Z TAFs)
Issued at 701 PM EST Fri Dec 27 2024
Isolated to scattered showers are ongoing across portions of east
central Florida this evening. Prevailing SHRA at FPR/SUA with TEMPOs
through 03Z for VIS reductions in heavy downpours. Otherwise, VCSH
mentioned at coastal terminals. There is potential for stratus to
build again tonight. Models have significantly backed off on CIG
reductions since the 18Z TAF package. Have raised CIGs slightly
across the northern terminals overnight, but have opted to keep at
least MVFR CIGs for these terminals based on previous nights trends.
East-southeast winds 3-5 kts overnight, remaining slightly higher
along the Treasure Coast. Winds increase to around 10-12 kts by late
morning and into tomorrow afternoon with gusts up to 22 kts along
the coast.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 64 76 65 77 / 30 20 30 60
MCO 65 78 66 78 / 20 30 30 60
MLB 66 77 66 77 / 30 30 30 60
VRB 67 79 68 80 / 60 30 30 60
LEE 64 79 65 77 / 20 30 40 60
SFB 64 78 65 78 / 20 30 30 60
ORL 65 79 66 78 / 20 30 30 60
FPR 67 78 67 80 / 60 30 30 60
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 10 PM EST this evening for AMZ570-572.
&&
$$
UPDATE...Heil
AVIATION...Law
Area Forecast Discussion
National Weather Service Marquette MI
702 PM EST Fri Dec 27 2024
.KEY MESSAGES...
- Widespread rain will move in to the region tonight and linger
Saturday.
- Areas of fog, locally dense (reducing vis to 1/4 statute
mile), continue through at least Saturday.
- Unseasonably mild temperatures continue through Monday with
highs averaging 10-20 degrees above normal and lows around
20 degrees above normal.
- Temperatures trending back to normal by New Year`s Day with
lake effect snow developing in the northwest wind snow belts.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 155 PM EST Fri Dec 27 2024
A soupie day has taken place across central and parts of eastern
Upper Michigan thanks to the a warm, moist airmass aided by upslope
flow. The lowest visibility has been observed via webcams across
higher terrain areas of central Upper Michigan. Pockets of light
rain/drizzle have also been noted thanks to low level isentropic
ascent through this moist layer. Daytime temps have been observed
well into the 30s across the region.
Board troughing across western CONUS, as noted on GOES water vapor
and RAP analysis, will continue pressing eastward tonight and
Saturday. A shortwave embedded in this trough stretching across the
Plains will amplify in response to favorable left exit region jet
dynamics, resulting in a surface low developing today then lifting
northeast into the Upper Great Lakes overnight into Saturday. Ahead
of this wave, low level isentropic ascent within a saturated airmass
will continue to support areas of low visibility and drizzle/rain
for the remainder of today, mainly focused across central and
eastern Upper Michigan. Lowest visibilities will be focused in the
central portions, where light southeasterly flow will support
upslope flow. This evening though, winds become more easterly as the
upstream low lifts into the region. This may result in improving
visibilities at least until tonight when they drop again.
Widespread light rain is expected to lift north to south through the
forecast area overnight and then ending south to north through the
day Saturday. As noted by previous discussions, abundant moisture
will be available with this system. However, with the progressive
nature of the system, QPF is likely to remain less than an inch, so
hydro concerns are not expected. Basin average QPF is expected to
range from 0.25-0.75". Expecting continued fog, especially central
Upper Michigan where upslope flow could support some dense areas
into Saturday. Opted to extend the Dense Fog Advisory through 12z
Saturday. Overnight lows are expected to remain above freezing in
the mid 30s across the forecast area tonight and remain well above
normal Saturday with highs in the mid 30s to low 40s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 354 PM EST Fri Dec 27 2024
The long term forecast will be driven by a 500mb pattern of building
ridging over the Rocky Mountains and longwave troughing over the
eastern CONUS with a number of shortwaves pivoting around the core
of the longwave trough as it moves from the Canadian Prairie through
Ontario throughout the week. Flow aloft becoming more northwesterly
will allow for a cooler airmass to flow into the Upper Great Lakes
region, bringing temperatures back down to seasonal by the middle of
the week and potentially cooler than normal by the end of next week.
While synoptic snowfall seems to elude the region for the most part,
cooler air aloft will support the return of lake effect snowfall,
primarily in the northwesterly belts.
Saturday night, rain will finish lifting to the northeast with sub-
10% chances of precipitation in the 06Z-12Z time period per the
LREF. Throughout the overnight and Sunday morning period, shortwave
troughing will pivot from OK/AR to the Chicago metro,
supporting a deepening mid-990s to low 1000s mb low pressure
pivoting through Lower Michigan and Lake Huron before lifting
northeast into Canada. The NBM carries 20% chances of light
precipitation in the far eastern UP with this system, with
temperatures falling towards the freezing mark, there`s chances
that the precip could fall as rain or snow. However, regardless
of exact precip type, the LREF only gives 15% or less chances of
the eastern UP seeing a half inch of snowfall accumulation
prior to 12Z Monday, so even a "worst case scenario" would not
be particularly impactful.
The final days of 2024 into the beginning of 2025 will see cooling
temperatures as 500mb heights aloft fall with the core of longwave
troughing moving near the UP. With Lake Superior remaining around 5
C, the target for 850mb temperatures to support lake effect snow
will be around -8C. By the time of the 25th anniversary of Y2K, the
LREF shows 850mb temperatures over 90% likely over the west half of
Lake Superior, spreading across the rest of the lake by the
afternoon of the 1st. A return of lake effect snow will help bring
the snowpack back after the toll taken on the snowpack by this
week`s warmth and rain. Ensembles are coalescing around the 925mb
wind direction being NWerly, the Canadian ensemble falling in line
with the other ensembles in showing the NWerly pattern. However,
uncertainty in the availability of low level moisture (tied to the
shortwave evolution elsewhere outside of the UP influencing moisture
transport) will keep the details of snowfall rates and impacts muddy.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 701 PM EST Fri Dec 27 2024
Abundant low level moisture is producing fog and stratus that will
continue into Saturday. Additionally, an area of low pressure will
lift into the area tonight, bringing rain to all terminals into
Saturday. KSAW will continue to experience LIFR to VLIFR conditions
through Saturday afternoon, with conditions below airport minimums
for much of that time. Late in the TAF period, KSAW will improve to
IFR as westerly winds increase. KCMX will see low end MVFR this
evening, before falling back to LIFR overnight. As the westerly
winds increase Saturday afternoon, KCMX will improve to IFR. KIWD is
currently shifting from VFR to IFR and these conditions should
continue through the evening hours thanks to nearby terrain
supporting downsloping flow. However, overnight conditions
deteriorate to prevailing IFR, potentially LIFR by morning with
conditions improving to IFR by afternoon. Westerly to southwesterly
winds with gusts to 20 kts are expected Saturday afternoon.
&&
.MARINE...
Issued at 354 PM EST Fri Dec 27 2024
A low approaching from the southwest will bring the 20-25 kt
southeasterly wind gusts in the east half of Lake Superior to near
30 kt with a few gale force gusts to 35 kt possible between
Whitefish Point and Caribou Island (20-30% chance). Winds will
quickly turn to the west/southwest as the low passes Saturday, with
gusts to near 25 kt late Saturday into Saturday night. From there,
the winds will remain mainly below 20 kt through the end of 2024
except for some northwesterly wind gusts to 25 kt over the eastern
end of the lake Monday evening as a low pressure passes northeast
through Lower Michigan and Lake Huron. Building high pressure to the
west of Lake Superior while deep low pressure remains to the east of
the Great Lakes will tighten the pressure gradient, encouraging near
25 kt winds broadly out of the northwest to kick off 2025.
&&
.CLIMATE...
Issued at 345 AM EST Wed Dec 25 2024
Record warm highs and lows at WFO MQT in Negaunee Township (records
date back to 1959):
Date High Low
Dec. 27 42 (1994/2008) 32 (2008)
Dec. 28 42 (1979) 34 (2003)
Dec. 29 43 (1979) 31 (2022)
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Dense Fog Advisory until 7 AM EST /6 AM CST/ Saturday for
MIZ004>006-010>013.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JTP
LONG TERM...GS
AVIATION...RM
MARINE...GS
CLIMATE...