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Nelson

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  1. FXUS63 KMKX 082150
    AFDMKX
    
    Area Forecast Discussion
    National Weather Service Milwaukee/Sullivan WI
    350 PM CST Thu Dec 8 2022
    
    .SHORT TERM...
    (Issued 350 PM CST Thu Dec 8 2022)
    
    Tonight through Friday night:
    
    The main forecast changes: 1) delayed the arrival of snowfall
    across east-central Wisconsin where drier air will put up a fight,
    2) shifted the main axis of snow about 50 to 100 miles south, 3)
    expanded the Winter Weather Advisory to the south and east, and 4)
    used 10th-90th percentile for snowfall totals online. More
    details below!
    
    The main focus tonight through Friday night is on the banded area
    of moderate to heavy snow expected to lift through southern
    Wisconsin late tonight through approximately mid-day Friday. While
    the wave is deamplifying as it approaches the area, there is
    still an overabundance of large scale ascent moving through the
    area. With WAA nosing in ahead of the shortwave, a transient area
    of 850-700mb frontogenesis also sharpens across the area, bringing
    a more focused area for localized ascent. The 12Z HREF does show
    the potential (20-40% chance) we could see some embedded areas
    within the band where snowfall rates could approach 1 inch per
    hour. Thus, as the this band moves through expect snowfall rates
    to pick up and visibilities to become sharply reduced. Opted to go
    with 10th-90th percentile for snowfall, as it handled the
    uncertainty across our northern counties and lakeshore counties
    well, while adding in some potential for locally higher amounts
    where the banded area of snowfall tracks.
    
    Where does this band track? Well, it will be highly dependent on
    how the drier air currently over the region and upstream of the
    area holds on. High-res models really limit the higher QPF and
    snowfall potential across Marquette/Green Lake and portions of
    east-central Wisconsin given the easterly winds advecting in
    drier air from the southern extent of high pressure up near the
    Hudson Bay. This drier mid-level air was sampled well by the 12z
    soundings from KAPX and KDTX. Thus, the latest RAP/HRRR keep the
    better chances for accumulating snow within the banded feature
    roughly along and south of I-90/I-94. Whereas the NAM/GFS do
    continue to show some potential for better QPF and snowfall up
    into central Wisconsin. Thus, did keep the original Winter
    Weather Advisory as is, and added counties to the south and
    southeast to account for the shift to the southeast with the high-
    res guidance.
    
    As for p-types, we could still see some freezing rain develop
    ahead of the banded area of snow late tonight. As the mid-level
    dry air erodes, soundings do show some potential for temperature
    aloft to remain above freezing briefly while surface temperatures
    hover around freezing. The NBM v4.1 probabilities support the
    potential for freezing rain early on, thus have continued to
    include mentions in the forecast. Otherwise, once the band of snow
    moves in, even along Lake Michigan, dynamical cooling and robust
    forcing along the band of frontogenesis will help keep
    precipitation in the form of snow. Due to the pronounced lift, did
    run the weather type forecast using surface wet-bulb temperatures
    of 35 for the cutoff for snow mentions. As easterly winds
    continue throughout the day and temperatures warm near Lake
    Michigan, this will help favor a transition over to rain/snow or
    rain during the afternoon hours. Then as the banded area of snow
    moves east, exiting over Lake Michigan and weakening, we will lose
    cloud ice and should see a transition over to drizzle or freezing
    drizzle. Surface temperatures will be critical Friday night into
    Saturday, as freezing drizzle may linger and lead to some impacts
    given the lingering 850mb WAA stream up into the area.
    
    Anderson
    
    • Like 1
  2. 16 minutes ago, Chicago Storm said:


    It would have a negative impact in terms of potential, and is about one of three reasons why there’s been a shift south/weaker overall in guidance the past day or two.


    .

    Did I get the northern stream energy right and the fact that it's trending slower/deeper?

  3. Curious/trying to learn a little bit. Both the GFS/Euro seem to be trending slower/deeper with the northern stream piece of energy. What impact does that potentially have? Favor a better chance of phasing, thus a stronger (possibly negative tilt system)? Or something else? Or am I completely not looking at this correctly?

    gfs_z500_vort_us_18.thumb.png.6fac9ad14e8291a90d4ead6a23688553.png

    gfs_500_trend.thumb.gif.46d338fa47d5bab59d6c74aee6bac3be.gif

     

  4. 22 hours ago, Brian D said:

    Haven't been around in a while. Lost my youngest son, Daniel(26) back on the 16th. Very trying time for me and my family. Starting to get back to a little bit of normalcy. 

    That being said, looks like more storms moving through today. Already some svr weather west of me this morning.

    Damn, sorry to hear about the loss of your son. As a father, it's hard to imagine having to endure something like that so I hope you and your family can find some peace through all of it. 

    • Like 5
    • Thanks 1
  5. 5 hours ago, Baum said:

    interesting not seeing much discussion regarding GFS in theses more under the hood AFD's

    MKX: Lame. Maybe the worst midwest discussions out there these days.

    MKX definitely been hit or miss with the AFDs as of late. I think Wood (if I'm recalling the name correctly) typically does a good job with the write ups. Sorry for the OT

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