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lookingnorth

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Posts posted by lookingnorth

    Texas/Oklahoma 2023 Obs and Discussion

    in Central/Western States

    Posted

    While the heat has eased up somewhat the past few days (thankfully), we could really use some rain. Most of the state has not seen a drop of rain in the past two weeks. Most of the OKC metro has seen less than an inch of rain in the past seven weeks. We haven't even had a cloudy day in quite some time. The long stretches of hot, dry, sunny weather really get to me after a while.

    • Like 1

    General pollution discussion ?

    in Climate Change

    Posted

    I like the topic idea. I am enrolled in a course on atmospheric radiation currently, and it is interesting learning about how aerosols influence atmospheric conditions. I have heard it claimed that the May 20, 2019 severe weather outbreak was weakened due to dust aerosols from further west. But I'm not a huge expert on the topic.

    I've also heard it said that switching from coal to natural gas may not be as beneficial in reducing climate change as people had hoped, because the aerosols from coal combustion help cool the climate and counteract some of the CO2 emissions from burning coal. But those aerosols still have negative direct effects on human health, so it is still better to switch.

    Severe potential 2/26

    in Central/Western States

    Posted

    16 hours ago, Chinook said:

    confirmed tornado passed US77 highway on the south side of Norman

    That thing hit about a mile from my house. I know some people who sustained minor damage from the tornado. Luckily I was okay and avoided any damage and didn't even lose power.

    • Like 1

    MO/KS/AR/OK 2022-2023 Winter Discussion

    in Central/Western States

    Posted

    For the Monday event, the NAM has been consistent in showing snow over western Oklahoma, with less in the OKC and Tulsa metros. NWS Norman mentioned a lot of uncertainty in their morning forecast discussion.

    Quote 
    An early season winter weather event still appears on track to
affect the area on Monday, but there are still a number of key
details to be worked out regarding where and how much snow will
fall. Models agree that a compact shortwave will move quickly
eastward into west Texas Monday morning, with ascent increasing
rapidly in our area as it does so. The shortwave will be weakening
over time as it phases with broader closed low to our north, with
forcing decreasing quickly near or after 21z Monday across much of
the area. Therefore, the vast majority of precipitation is expected
to fall during the daytime on Monday, with a fairly brief (3-6 hour)
window for snowfall at any one location.

There has been a southward shift in much of the model guidance over
the last 24 hours, along with a trend towards a weaker shortwave as
it crosses into Oklahoma. Most hi-res model guidance has converged
on a swath of heavier QPF from western/west-central OK southeastward
into southern OK, while the ECM/GFS and their respective ensembles
remain a bit further north and east centered more along the I-40
corridor.

With thermal profiles initially too warm for snow outside of
northwest Oklahoma and surface wet-bulb temperatures at or above
freezing, heavy precipitation rates will be needed to cool the
column sufficiently for accumulating snow. Therefore, the placement
of this band will likely be the key determining factor for who sees
several inches of heavy wet snow and who sees little more than a
light rain/snow mix with minimal accumulation. We have adjusted our
snowfall forecast southward from the previous forecast and increased
amounts within the band of heavier precipitation, though our
forecast is likely too broad with accumulating snow (especially
across north-central Oklahoma) and may be too conservative on
maximum amounts due to remaining uncertainty. As of now our highest
amounts (2-3") are across northwestern OK southeastward into central
OK, but it is possible further adjustments southward will be needed
if trends continue. Of note, many of the latest hi-res models
produce little to no snow accumulation for portions of central and
north-central Oklahoma, including parts of the OKC metro, as the
heavier precipitation fails to make it north and east during the
day Monday before forcing wanes. All in all, forecast confidence
remains low and users are advised to check back for further
updates.

     

    Central/Western Medium-Long Range Discussion

    in Central/Western States

    Posted

    On 8/27/2021 at 11:56 AM, Powerball said:

     

    How many other years, besidea 2004, has OKC not hit 100*F+?

    DFW has only had 6 so far, and they all occured in that late July / early August period.

    I now know better than to say it won't happen for sure, especially with the help of subsidence behind Ida next week, but it is getting increasingly less likely that DFW will see any more 100*F+ days this year.

    19 other years

    • Like 1

    Historic Pacific Northwest Heatwave of 2021

    in Climate Change

    Posted

    1 hour ago, donsutherland1 said: 
    
000
NOUS46 KOTX 300126
PNSOTX
IDZ001>004-026-027-WAZ031>038-041>044-301326-

Public Information Statement
National Weather Service Spokane WA
626 PM PDT Tue Jun 29 2021

...PRELIMINARY HIGH TEMPERATURE REPORTS...

Location                     Temp      Time/Date       Provider

...Idaho...
...Chelan County...
3.6 SE Ardenvoir             119 F     0130 PM 06/29   HADS
1.2 S Peshastin              119 F     0345 PM 06/29   HADS

     

    If those 119's are verified, that would be a state record for Idaho, right?

    • Like 1

    Historic Pacific Northwest Heatwave of 2021

    in Climate Change

    Posted

    18 hours ago, donsutherland1 said: 
    
Weather summary
for British Columbia
issued by Environment Canada
at 5:36 p.m. PDT Monday 28 June 2021.

Discussion.

The following data is preliminary and will be updated later tonight 

The following areas will have set a daily maximum temperature record 
on June 28, 2021: 

Abbotsford Area (Abbotsford A) 
Preliminary new record of 42.9 
Old record of 32.4 set in 2008 
Records in this area have been kept since 1944 

Dawson Creek Area (Dawson Creek A) 
Preliminary new record of 38.1 
Old record of 27.8 set in 2015 
Records in this area have been kept since 1926 

Gibsons Area (Sechelt Aut) 
Preliminary new record of 40.1 
Old record of 29.6 set in 2008 
Records in this area have been kept since 1949

     

    Looks like some places broke their daily records by over 10°C!

    • Like 1

    Adiabatic lapse rate

    in Climate Change

    Posted

    On 12/13/2020 at 10:46 AM, Leitwolf said:

    The adiabatic lapse rate is the key component of the GHE. Regrettably I do not seem to fully understand it and so I need to ask for help.

    The average lapse rate on Earth is about 6.5K/1km. The "dry" lapse rate however is said to be 9.8K/km. So vapor (and the latent heat it transports) reduces the lapse rate significantly, in this way it also serves as a kind of anti-GHG. I mean if we understand the GHE as a combination of an elevated emission layer (photosphere) where we have 255K and the adiabatic lapse rate, which produces higher temperatures at the surface. Anyhow, the exact impact of vapor on the lapse rate is a key question.

    Now I found this sightly confusion chart on the subject on wikipedia. There are some things I understand, and some things I don't. For instance we have lines for altitude (scale on the right) which are sloped. That is to be understood relative to the left scale of pressure, meaning with cold air pressure will decrease faster with altitude, as it has a higher density.

    https://en.wikipedia.org/wiki/Lapse_rate#/media/File:Emagram.GIF

    Now if I look at the bold line for the dry adiabat, for instance the one starting at 20°C, it intersects the 5km line at roughly -24°C. That are 44K for 5km, or 10.8K/km, significantly more than the 9.8K quoted before. Assuming the chart is right, what causes this difference? Is it because the troposphere is naturally unstable and heated at the surface, so to say?

    Then the "wet" lapse rate starting at +15°C intersects the 5km line at about -14.5°C, meaning a delta of 29.5K or 5.9K/km. +15°C roughly corresponds to the actual surface temperatures on Earth, yet 5.9K/km is significantly less than the quoted 6.5K. Why is that? Is it representing a more theoretical perfectly wet atmosphere with a 100% H2O saturation??

    I have no idea why the dry adiabatic lapse rate is so great in the chart. I've only ever used Skew-T log-P charts, not emagrams. However, the moist adiabatic lapse rate varies significantly based on temperature, and 5.9K/km is well within the range of possibility. The average environmental lapse rate is not the same as the average moist lapse rate because sometimes the atmosphere will be dry adiabatic, sometimes there will be an inversion, etc. But since the atmosphere is often moist adiabatic, the two happen to be similar.

    Arctic Sea Ice Extent, Area, and Volume

    in Climate Change

    Posted

    On 11/1/2020 at 12:56 PM, bdgwx said:

    It's complicated. First understand that this is not entirely unexpected. In fact, the IPCC AR5 WG1 prediction for SH sea ice, although significantly more uncertain than predictions for the NH, shows a slight preference for increases through about 2030 with the possibility of record highs persisting even through 2060 before things turn south (pun intended) down there too. I must caveat that by saying the uncertainty envelope does include the possibility of the secular decline starting around 2020 as well. The unfortunate state of affairs with SH sea ice is that our understanding of its behavior in a warming world is still quite nebulous compared to our understanding of NH sea ice behavior. Second understand that the see-sawing of temperatures and sea ice between hemisphere has been shown to occur during previous significant climatic change events so it is not unprecedented nor is it inconsistent with climatic shifts.

    Anyway here are some things to consider...

    • The NH is characterized by ocean surrounded by land whereas the SH is land surrounded by ocean. This trivial fact accounts for the bulk of the differences between NH and SH sea ice behavior. The consequences of this can be quite dramatic and contradictory between the NH vs. SH.
    • A positive phase of the Southern Annular Mode (SAM) is associated with increasing SH sea ice. Global warming tips the SAM toward a positive phase.
    • ENSO negative/positive phases reinforce positive/negative SAM phases.
    • The Montreal Protocol through its ban of CFCs, repair of stratospheric ozone, associated cooling tendencies and other effects on weather patterns has been linked to SH sea ice increases.
    • Increasing GHGs actually have a cooling effect on the Antarctica continent itself especially during the SH winter when the upper atmosphere is often warmer than the surface. Remember, GHGs act like a thermal barrier preventing IR radiation from passing through. This causes the warm/cool side of the barrier to warm/cool further. Positive/negative lapse rates get more positive/negative. Antarctica often has a negative lapse rate during the winter so GHGs cause cooling at the surface and warming in the upper atmosphere. This effect (among others) suppresses polar amplification in the SH.

    Disclaimer...I'm not well informed regarding SH sea ice so hopefully others who know more about the behavior down there can chime in on points I've missed or mischaracterized.

    The main take away here is that sea ice is mainly a NH issue right now. Most scientists do not expect NH-style declines in sea ice down in the SH anytime soon. And the fact that the SH responds differently than the NH is probably more the rule than the exception. 

    I'm not an expert either, but I did a class project on it last spring and that's basically what I found. The change in lapse rates thing is new to me, but it makes total sense.

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