Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/24/23
Area Forecast Discussion
National Weather Service Grand Rapids MI
1039 PM EDT Sun Apr 23 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1039 PM EDT Sun Apr 23 2023
No changes planned to the Freeze Warning tonight. That said, there
is a significant amount of cloud cover around at this time and
much of it may hold on through the night. So, some of the colder
readings, dropping into the upper 20s, may not be realized.
Charlotte is already down to 36 though, so we will not have to
fall much further to get to critical values.
An inversion around 9,000 feet seen on the DTX sounding and other
ACARS soundings may tend to trap the moisture beneath it tonight.
At this point the ceilings are below this level for the most part,
but this moisture may lift a bit and become trapped. Bottom line,
we may see more in the way of cloud cover tonight which should
keep readings in check somewhat.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 203 PM EDT Sun Apr 23 2023
- Risk for freezes most nights through Wed night
The deep mid level low will continue to remain over the
Great Lakes region through Wednesday when it starts to track
east as a ridge moves in for Thursday. Each night through
that period will feature temperatures falling to near or
below freezing...raising the risk for impacts. Cloud cover is
forecast at times so there exists some uncertainty as far as
how widespread the impacts will be. Wednesday night may be
the coldest night as the low finally moves away with a period of
ridging and associated decrease in cloud cover leading to what
may be the best radiational cooling night of the week.
We will issue a freeze warning for tonight. We are running 3 to 4
degrees colder than this time yesterday. This will likely
translate into tonight`s low temperatures being a few degrees
colder than last night. Most locations ended up in the 29 to 34
degree range away from Lake MI this morning. While guidance
suggests the cloud cover may persist overnight...high res models
are generally suggesting overnight lows will be several degrees
colder than last night.
A weak mid level wave tracks through Tuesday with clouds and
perhaps some showers...but that system moves east of the region
Tuesday night. After a cool start to the night...any clearing
should support temperatures potentially falling near or below
freezing once again.
Ensemble min temperature guidance adds confidence to the freeze
potential each night with mean values for inland locations falling
to near or just below freezing and not a lot of spread amongst the
members.
- It`s looking wet for the end of the week into next weekend
A series of mid level waves are progged to dig down into the
Central Plains Friday into Saturday leading to a closed low. To
the east of this system backing flow through a deep layer here in
MI will draw up Gulf moisture that will wrap around this closed
low as it track through the area on Sunday. Based on the inflow of
moisture and falling heights with the deepening system...the
pattern here in MI for now looks wet and on the cool side. We will
continue to feature below normal temperatures settling in and
higher than normal POPs for this period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 836 PM EDT Sun Apr 23 2023
Conditions are expected to remain VFR through the TAF period.
Clouds are in general expected to scatter out a bit, but there is
some concern that they hang on. Cyclonic curvature remains tonight
at about 5,000 feet which helps in the production of cloud cover.
In addition, enough instability remains over Lake Michigan that
clouds will likely continue to stream in off the lake. Even if
they do however, bases will likely stay in the 4,000 to 8,000 foot
range. A much better chance of scattering out will come on Monday
when ridging begins to take hold. Winds will gradually diminish
this evening to light and variable tonight.
&&
.MARINE...
Issued at 203 PM EDT Sun Apr 23 2023
The winds and waves will gradually diminish this evening as the
mixing heights decrease. Thus we will allow the small craft
advisory to expire at 4 pm today. Looking ahead the risk for
hazardous conditions for small craft is low for much of the week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Freeze Warning until 8 AM EDT Monday for MIZ050>052-056>059-
064>067-071>074.
LM...None.
&&
$$
UPDATE...Duke
DISCUSSION...MJS
AVIATION...Duke
MARINE...MJS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
631 PM CDT Sun Apr 23 2023
.SHORT TERM...
Issued at 303 PM CDT Sun Apr 23 2023
Through Monday night...
Conditions have pretty much remained dry thus far today. A few light
showers have managed to pop up over parts of northern Indiana as
well as southern portions of the lake. This is likely due, at least
in part, to the lack of low level moisture early this afternoon.
Recent ACARS soundings out of O`Hare and Midway show that the low
levels aren`t quite as moisture-rich as forecast soundings insist
they should be at this point. And with rather subtle forcing in
place, it`s understandable that the shallower saturation is
inhibiting precip development for the time being. A handful of
models have the light rain coverage expanding over the CWA later
this afternoon as the low-mid level vort max swings in from the west
and we get a bit more forcing to work with. Additionally, models are
hinting at some modest low level moisture advection along the vort
over the next couple of hours which too would help showers to get
going. However, areas upstream remains dry as well aside from some
apparent virga over parts of southwest Wisconsin. This is all to say
that chances over the next several hours are looking slight. In
terms of precip type, we should see predominantly rain, that is if
we see anything at all. Although, the possibility of a few
snowflakes mixed in can`t be disregarded with the top of the moist
layer sitting at around -13C or so and wet bulb zero heights at just
a few hundred feet off of the surface.
We`ll gradually part ways with higher dewpoints aloft through the
evening as the vort ejects to the east and higher pressure works
in cutting off precip chances. The dry advection will also do well
to clear up most of our cloud cover this evening and overnight
(maybe enough to catch a glimpse of the northern lights that may
be visible into northern Illinois tonight???). The partly cloudy
skies and modest cold advection will pull temperatures back into
the lower 30s tonight and early Monday morning. The majority of
the area is expected to see sub-freezing temperatures aside from
downtown Chicago and adjacent areas.
Some mild return flow on the backside of a high pressure center to
the south will allow temperatures to climb into the lower 50s
tomorrow afternoon. This high will keep conditions dry for most of
the day. A rather potent little shortwave is progged to develop over
Iowa Monday evening and provide us with some rain chances beginning
in the evening and building overnight as the wave picks up some
momentum and moves overhead. Rain is expected to hang in the area
for a good deal of Tuesday as well before the wave moves off to the
east in the afternoon and drier air works in from the northwest.
Temperatures on Tuesday will once again top off in the lower and
middle 50s.
Doom
&&
.LONG TERM...
Issued at 251 PM CDT Sun Apr 23 2023
Tuesday night through Sunday...
High latitude blocking near and southwest of Greenland,
associated with the negative phase of the NAO (North Atlantic
Oscillation), will continue to support mean troughing (negative
geopotential height anomalies) and generally below normal
temperatures from the Midwest eastward across the Great Lakes
region through most of the period. Locally, this weather pattern
will support primarily dry weather Tuesday night through Thursday
as a cool Canadian surface high shifts across the area. However,
following a brief moderation in temperatures Thursday into Friday,
a renewed strong upper trough/low is expected to redevelop over
the region by next weekend. Accordingly, the area should see a
return to unseasonably cool conditions and a period or two of
precipitation next weekend.
Following our precipitation chances during the day Tuesday,
surface high pressure is expected to begin shifting southward into
the Upper Midwest Tuesday night. A drier and cooler airmass
associated with this feature may allow temperatures to drop off
to near, or just below freezing in parts of north central IL
Tuesday night, but this will ultimately be dependent upon how
quickly we lose the cloud cover.
The surface high is expected to shift south-southeastward over the
Great Lakes Wednesday into Wednesday night. Persistent onshore
winds during the day Wednesday will likely keep areas near the
lakeshore in the 40s during the day, while areas inland likely at
least climb into the 50s. The potential then exists for another
chilly night Wednesday night as winds look to potentially be light
and skies mainly clear. If this pans out, we could see
temperatures drop below freezing again, especially for areas
outside the immediate Chicago area.
Temperatures look to briefly moderate for inland areas late in
the week as the nearly stagnant upper low over the Great Lakes
finally weakens and begins to lift northward into Canada. This
should allow inland highs to return back into the low 60s, but
lake breeze potential is likely to again result in cooler
conditions along the lakeshore. Unfortunately, any improvement in
temperatures later in the week is likely to be short lived. Model
and ensemble guidance are in agreement that a renewed strong upper
trough/low redevelops/digs over the region late Friday into next
weekend. The net result of this being high chances (50%+ chances)
for more precipitation, and a return to unseasonably cool
conditions next weekend.
KJB
&&
.AVIATION...
For the 00Z TAFs...
VFR conditions are forecast through the period. Overcast skies
continue this evening with the potential for rain and snow showers
decreasing with each passing hour, thus have opted to go dry with
this update. It is also becoming less certain if skies fully clear
out tonight with latest guidance trending more pessimistic.
Winds will generally favor a westerly direction through Monday
afternoon though they may become light and variable at times
overnight. A late afternoon lake breeze push is expected at MDW and
ORD turning winds easterly (early afternoon at GYY).
Petr
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Freeze Warning...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-
ILZ033-ILZ039-ILZ103-ILZ105-ILZ106-ILZ107-ILZ108...midnight
Monday to 8 AM Monday.
IN...Freeze Warning...INZ001-INZ002-INZ010-INZ011-INZ019...midnight
Monday to 8 AM Monday.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
809 PM PDT Sun Apr 23 2023
.SYNOPSIS...23/805 PM.
The cooling trend will continue through Monday with increasing
onshore flow and an increase of night through morning low clouds
and fog. A warming trend is forecast for the middle and end of
the week, especially for interior areas.
&&
.SHORT TERM (SUN-WED)...23/807 PM.
An upper level trough of low pressure moving into the Great Basin
has generated increasing onshore flow and a marine layer influence
across coastal areas. This resulted in a cooling trend across most
areas today. The strengthening onshore flow (LAX-Daggett peaked
at +6 mb this afternoon) combined with an eddy circulation has
resulted in low clouds and fog hanging across immmediate portions
of the LA county coast and points southward this afternoon. For
this evening, low clouds are moving inland rapidly across the
Central Coast and LA county coast. ACARS data showed the marine
layer depth around 1300 feet across the LA Basin this evening. The
marine layer depth is expected to increase to around 2000 feet by
Monday morning, resulting in low clouds and fog filling into most
valley areas, along with a cooling trend for much of the region
on Monday. In addition, the deepening marine layer combined with a
low level southerly flow depicted in model cross sections could
generate patchy drizzle for LA County coastal/valley areas on
Monday morning. In addition, there will likely be some upclope
clouds generated on the north facing slopes later tonight and
Monday morning, with a 10 percent chance of light rain.
The other shoft term concern tonight are gusty west to northwest
winds across the region. Wind advisories are in effect until 3 am
tonight for southern Santa Barbara County, the I-5 corridor, and
the Antelope Valley where gusts of 40 to 50 mph are expected to
persist. The current Sabta Narbara-Santa Maria pressure gradient
is at -3.9 mb which is slightly weaker than this time last night,
but northwest upper level wind support is slightly stronger due
to the passage of the upper level trough to the east. Similar
gusty west to northwest winds are expected on Monday afternoon
through Monday night, and may require additional wind advisories
across the same areas as tonight.
*** From previous discussion ***
Monday into Monday night will be fairly similar with broad
northwest flow aloft possibly supporting another round of advisory
level winds for similar areas. Not expecting a significant change
in the marine layer and associated low cloud coverage. Just like
today, low clouds and patchy fog may linger along some beaches
(best bet along and south of Santa Barbara) well into the
afternoon.
Tuesday into Wednesday kicks off a pronounced warming trend,
initially for interior areas as a ridge builds in from the west.
Coastal valleys are likely next in line for stronger warming
trends by Wednesday as offshore trends with possible weak
offshore flow and building 500 mb heights join forces to squash
the marine layer towards the coast and delay or even eliminate
the cooling effects of the sea breeze. Warmer coastal valleys may
warm into the low to mid 90s by Wednesday if offshore flow is able
to squash the marine layer to the coast. Some guidance suggests
the offshore winds will make it into coastal areas, but given
unseasonable cold water temperatures and an established and
strengthening marine layer inversion, there is only a small chance
that this occurs. Even above and inland of the marine layer,
winds should remain below advisory level during this time.
.LONG TERM (THU-SUN)...23/215 PM.
Above normal temperatures may persist into next weekend as
ensemble guidance has slowed and amplified the ridge in the
region. However, the marine layer may slosh back into some coastal
valleys as offshore flow wanes, especially if an eddy manages to
develop thanks in part to typical northwest Sundowner winds
across southwest Santa Barbara County. So any day-to-day changes
in the marine layer will have a stronger influence on temperatures
west of the mountains during this time frame. Onshore trends
during this time and a strong marine inversion may support slow to
no afternoon clearing of low clouds and fog to some coastal
areas.
&&
.AVIATION...24/0014Z.
At 22Z, the marine layer depth was around 1300 feet deep at KLAX.
The top of the inversion was around 2100 feet with a temperatures
around 18 degrees Celsius.
Moderate confidence in the current forecast for coastal and valley
terminals. High confidence in the current forecast for desert.
There is a moderate chance that conditions could arrive up to four
hours earlier than forecast and one category lower through 08Z.
There is a moderate chance that timing of improvement could be up
to two hours later than forecast. There is a low-to-moderate
chance that coastal terminals could not clear on Monday
afternoon.
KLAX...MVFR conditions will deteriorate to the IFR category
through 01Z. There is a 40 percent chance that IFR conditions
could linger later than 08Z. There is a 20 percent chance that
KLAX may not clear until as late as 21Z on Monday.
KBUR...IFR conditions will spread into KBUR as soon as 04Z, or as
late as 08Z. There is a 40 percent chance that IFR conditions
could linger later than 13Z.
&&
.MARINE...23/122 PM.
For the Outer Waters, moderate to high confidence in current
forecast. Gale force winds will continue through tonight. There
is a 60% chance that the Gale force winds may continue through
Monday, and the GALE WARNING has been extended through Monday
evening. High confidence in SCA level winds and seas Tuesday. For
Wednesday and Thursday, high confidence in winds and seas dropping
below SCA levels.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Tuesday, high
confidence in combination of SCA level winds and seas. There is
a 30% chance of Gale force winds today and tonight. For Wednesday
and Thursday, high confidence in winds and seas dropping below
SCA levels.
For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 70-90% chance of SCA level winds
through this evening, then a 50-70% chance of SCA level winds
continuing into Monday and Tuesday. Otherwise, high confidence in
winds and seas remaining below SCA levels today through Thursday
for the remainder of the southern Inner Waters.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Monday for zones
349-351-352-381-383. (See LAXNPWLOX).
Wind Advisory in effect until 5 AM PDT Monday for zone 378. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
for zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Monday for zone
650. (See LAXMWWLOX).
Gale Warning in effect until 9 PM PDT Monday for zones
670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Gomberg/Munroe
AVIATION...Hall
MARINE...Sweet/RAT
SYNOPSIS...Gomberg
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox