Ilya Neyman
EF1
I wanted to go ahead and start a thread regarding the possibility of an unseasonably cold and strong upper trough/closed low progged by latest GFS and ECMWF to develop over the Western US during mid-late next week.
This discussion will be based heavily on latest model trends, particularly the GFS, as such a situation is subject to change but given the very unusual nature of such a fcst feel the need to start this thread.
Overall synoptic situation features an unseasonably strong trough slamming into the Pacific NW during the Tuesday-Wednesday timeframe followed by progged deepening in response to a very powerful northerly jet on the backside of said trough. This is now indicated to further deepen and then close off a cold upper low with 500mb temps down to a whopping -20 C in late May!! 700 temps are fcst to be below 0 into the SoCal coastal waters Thursday!!
00z GFS drops this low through the Great Basin and then into Southern California during the Wed-Thu timeframe. As reinfocing energy dives through the flow the trough is forecast to continue digging, sandwiched between strengthening ridging both over the East Pac. and the Plains.
IF this forecasted scenario were to happen, an episode of unseasonable and interesting weather may occur over the Western and Southwestern States.
Such cold 500mb temps and strong vorticity would set-up serious cold-core instability, especially it being mid/late May. The potential for showers and thunderstorms would be quite real across portions of NV, SoCal, and AZ.
Depending on just how far the trough digs and where/how it exactly ends up will be significant to sensible weather from the West into the Plains. 12z ECMWF keeps the trough/closed low over the SW, and even retrogrades it toward/offshore later in the period.
This is typically the quietest time of year for this part of the country between winter storms and the summer monsoon season. A trough of this magnitude would be quite a rare occurrence!
Interesting thing to keep an eye on for everyone out West!
This discussion will be based heavily on latest model trends, particularly the GFS, as such a situation is subject to change but given the very unusual nature of such a fcst feel the need to start this thread.
Overall synoptic situation features an unseasonably strong trough slamming into the Pacific NW during the Tuesday-Wednesday timeframe followed by progged deepening in response to a very powerful northerly jet on the backside of said trough. This is now indicated to further deepen and then close off a cold upper low with 500mb temps down to a whopping -20 C in late May!! 700 temps are fcst to be below 0 into the SoCal coastal waters Thursday!!
00z GFS drops this low through the Great Basin and then into Southern California during the Wed-Thu timeframe. As reinfocing energy dives through the flow the trough is forecast to continue digging, sandwiched between strengthening ridging both over the East Pac. and the Plains.
IF this forecasted scenario were to happen, an episode of unseasonable and interesting weather may occur over the Western and Southwestern States.
Such cold 500mb temps and strong vorticity would set-up serious cold-core instability, especially it being mid/late May. The potential for showers and thunderstorms would be quite real across portions of NV, SoCal, and AZ.
Depending on just how far the trough digs and where/how it exactly ends up will be significant to sensible weather from the West into the Plains. 12z ECMWF keeps the trough/closed low over the SW, and even retrogrades it toward/offshore later in the period.
This is typically the quietest time of year for this part of the country between winter storms and the summer monsoon season. A trough of this magnitude would be quite a rare occurrence!
Interesting thing to keep an eye on for everyone out West!
