Day 56: Jets! Jets! Jets!
A very active upper-air pattern persists across the United States with several speed maximums inferred in tonight’s water vapor imagery. A powerful (fast) upper-level jet stream, with embedded jet streaks, is evident across the Gulf of Mexico into the far western Atlantic Ocean. This jet streak is aiding the development of the northeast “snowicane”, as I’ve heard it referred to by some in the media. A mid-level jet streak is propagating southeast out desert southwest into central Texas. This mid-level jet streak is aiding the development of a mid-level low over the northern Texas Panhandle. This mid-level low will slowly move southeast tonight, bringing with it the chance of a cold rain and even some snow (although, I’m not nearly as optimistic tonight about seeing much in the way of accumulations in central Oklahoma).
Below, I’ve annotated the mid-level lows (yellow X) and jet streams/jet streaks in thick cyan arrows. The thing cyan arrow is not necessarily a jet stream, but more of an indication of the flow pattern over the northeastern United States.
Lastly, I thought I’d show a graphic that helps explain why I’m not so gung-ho about central Oklahoma’s snow chances tonight/Friday morning. Below shows the northern hemispheric 500 hPa heights (color filled with lower heights in cool colors and higher heights in warmer colors) and surface pressure (solid black contours). The Day 50 post discussed how it appears a surge of arctic air was preparing to plunge southward out of Canada into the southern plains. Well, tonight’s northern hemispheric chart (below) clearly shows that the cold air did not plunge south into the southern plains. Thus, without a true source region of cold air needed for heavy snow, central Oklahoma should stay a tad too warm for much in the way of accumulating snow.
Now, central Oklahoma might see snow overnight, and here is how it would happen. As the upper-low and corresponding surface reflection move southeast across far eastern Texas panhandle and southwest Oklahoma into north central Texas, a lot of dry air from the east will become entrained into the storm. This dry air will allow evaporational cooling to occur, allowing surface temperatures to cool sufficiently for snow to reach the ground. However, whenever dry air is being continually advected into an area, this tends to decrease precipitation intensity…which would cut-back on any snow accumulations that might otherwise occur.
