Jump to content
  • Member Statistics

    17,508
    Total Members
    7,904
    Most Online
    joxey
    Newest Member
    joxey
    Joined

Late January and February Medium/Long Range Discussion


WinterWxLuvr
 Share

Recommended Posts

Morning AFD from LWX about the threat:

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
At the start of the long term period, a broad, positively tilted 
longwave trough will reside across central and western portions of 
the CONUS. Meanwhile, a strong subtropical ridge will be centered 
over the western Atlantic. This will result in a broad fetch of 
southwesterly flow aloft across the eastern half of the CONUS. At 
the surface, very strong Canadian high pressure (well over 1040 hPa) 
will descend from the Canadian Prairies toward the Upper Midwest. At 
the same time, a broad area of high pressure will be situated over 
the eastern Atlantic. A very strong baroclinic zone will develop 
along the interface between the cold, dry northerlies ahead of the 
Canadian high and the warm, moist southerlies on the backside of the 
oceanic high. On Wednesday this boundary will be oriented from Texas 
toward the Great Lakes. This boundary will gradually sag 
southeastward through the remainder of the week as the strong area 
of Canadian high pressure builds into the Northern Plains. At upper 
levels, a strong southwest to northeast oriented jet will develop in 
response to the strong temperature gradient along the frontal 
boundary. There is a broad consensus among deterministic and 
ensemble solutions that these larger scale features will be in place 
come Wednesday, Thursday, and Friday, but a fair amount of 
uncertainty remains with respect to the exact positioning of these 
features over time, and the resultant finer scale details of the 
weather forecast locally (especially as we move into Thursday night 
and Friday).

We'll reside on the warm side of the aforementioned boundary on 
Wednesday. Southerly flow will transport warmer temperatures into 
the area, with forecast highs expected to reach well into the 40s, 
and possible even the lower 50s. While it will be cloudy, not much 
in the way of precipitation is expected during the daylight hours. 
Chances for precipitation will increase Wednesday night into 
Thursday as the frontal zone approaches from the northwest. One or 
more disturbances may traverse through the southwesterly flow aloft 
and act to enhance precipitation within the broader zone of ascent 
ahead of the approaching trough, but there is considerable spread 
with respect to these finer scale details. However, models are in 
agreement that days worth of flow around the oceanic high will act 
to transport highly anomalous values (around 2-4 sigma, absolute 
values around 1-1.5 inches) of precipitable water out of the tropics 
and focus them along/ahead of this frontal boundary. As a result, 
heavy rainfall may be possible. As rains occur atop snow pack in 
western portions of the forecast area, localized instances of 
flooding may be possible. Wintry precipitation may also be possible 
by Thursday night into Friday as colder air starts to work into the 
area. However, spread in both the deterministic and ensemble 
guidance remains high. Very small changes in how relatively minor 
disturbances work through the strong southwesterly flow aloft could 
have major impacts on how the forecast evolves, especially with such 
a strong temperature gradient nearby.

By Friday night into Saturday, the longwave trough initially located 
off to our west will push offshore, driving a strong cold front 
through the area. Colder and drier conditions are expected in its 
wake.
Link to comment
Share on other sites

Besides 06z GFS being boring as hell, I do find it kind of funny that h5 at 150 a strong s/w is cruising into the West and then is like, oh wait, that little h5 cutoff low way SW of me looks tasteh... let me go SW for a bite... and proceeds to absorb that h5 and become some giant h5 low that has 5 closed contours (see 180) and finally kicks itself out at 204 like nothing happened...

  • Haha 1
Link to comment
Share on other sites

I have not really paid much attention to the late week deal, but just looking at the 0z runs of the ops/ensembles, the Euro/EPS, and to some degree the Canadian, have weaker low pressure along the Gulf coast and move it NE along the cold front such that the low tracks to our SE. The weaker nature of the low allows the cold to press east faster on the Euro. Canadian/CMC ens don't get the cold in quite as fast so its mostly rain. GFS has a stronger low tracking along the front further west and delays the arrival of colder air. GEFS mostly agrees but there are a a handful of members that imply some frozen. As usual, we watch the trends in the coming days.

  • Like 5
Link to comment
Share on other sites

1 hour ago, MD Snow said:

CMC, ICON and GFS want nothing to do with making this a threat. Nam and RGEM seem poised to follow at the end of their runs. My hunch is that Euro and Ukie lose it today or tomorrow at the latest. 

 

22 minutes ago, osfan24 said:

Hard to buy into a threat like this. The cold press is never as far south or as quick as models show. This will be congrats Central PA and NY.

Solid analysis by the both of you. We're lucky to have you!!

  • Like 1
  • Haha 8
Link to comment
Share on other sites

21 minutes ago, osfan24 said:

Hard to buy into a threat like this. The cold press is never as far south or as quick as models show. This will be congrats Central PA and NY.

Well, it is hard to argue that is the outcome more times than not in these setups, but there is a chance. Euro getting it done at this juncture.

The GFS 'dominance' over the Euro thing is mostly hyperbole btw. GFS blew chunks this last storm.

  • Like 2
Link to comment
Share on other sites

6 minutes ago, CAPE said:

Well, it is hard to argue that is the outcome more times than not in these setups, but there is a chance. Euro getting it done at this juncture.

The GFS 'dominance' over the Euro thing is mostly hyperbole btw. GFS blew chunks this last storm.

Exactly,   Euro had those big totals for Boston 4 days out.  GFS had it off the coast at 4 days.  

  • Like 2
Link to comment
Share on other sites

  • WxUSAF unpinned and locked this topic
Guest
This topic is now closed to further replies.
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...