Welcome to April! The next month looks like it'll be interesting, with warmer-than-average temperatures for much of the country, except the Northeast, where winter clings like tangy marinara to a plate of cold pasta. Sorry. This is no joke, either—we don't play those games. Nature really does just hate you.
We've been talking about the wavy jet stream forever, it seems, but things are finally starting to change around here. The broken jet stream broke, casting aside its ugly regime of a big ridge in the west and a big trough in the east for a more subtle pattern of waves across the United States. Generally, in the Northern Hemisphere, we tend to see warmer temperatures south of the jet stream and cooler temperatures north of the jet. This is why we saw record heat in the western United States while we dealt with some pretty hardcore cold across the eastern portion of the country for so much of the second half of the winter.
Here's an extreme example of the ridge-trough sequence we saw that led to such a wild difference in temperatures between the east and the west. This particular wave is from the cold snap in the middle of February.
Here's what the GFS model predicts the jet stream will look like on Thursday afternoon:
Thanks to this break in the jet that's allowing a more uniform air mass to set up across the country, it's finally going to feel like spring for just about everyone. Yesterday's six to ten day forecast from the Climate Prediction Center shows a huge slug of the country seeing a chance above-average temperatures, which actually means something around this time of the year. Unlike warmer-than-normal temps in the winter, you might start to break a sweat when it's above average in April. The average high temperature next week ranges from around 72°F in Atlanta to about 62°F in Lincoln, Nebraska.
The big exceptions to the rule are the Northeast, which is thawing out but still jacket-worthy, and the western United States, which is finally catching a much-needed break from its extended period of record-breaking warmth. The heat didn't go quietly: on both Monday and Tuesday, Death Valley broke its all-time high temperature for the month of March, reaching 103°F and 104°F for a high, respectively.
The CPC also expects above-average precipitation across the east over the same time period:
The eastern half of the country stands to see the potential for above-average precipitation, which almost always carries the risk for severe weather around this time of the year. This is about the time that everyone along and east of the Rockies should religiously check the Storm Prediction Center's website.
Oh, and there's a chance that it might snow around the Great Lakes and the Northeast over the next week or two. Sorry. By no means is snow unheard of in April (and even May!) around these parts, but it's frustrating to see your neighbors a state or two south wear shorts while you're watching snow coat the mud out your window.
The bigger story is what isn't happening in the western United States, where drought conditions continue with little relief in sight. Here's the drought monitor as of last week, which remains almost unchanged from the past couple of months.
The wet season is just about over for folks in the west, and barring any freak atmospheric phenomena, the drought is only going to get worse from here. The only potential relief in the models across the exceptional drought region is the northern Central Valley around Chico and Sacramento, where this morning's run of the GFS hints at the potential for an inch or two of rain next week.
The situation is so dire that California Governor Jerry Brown just signed the first ever statewide water restrictions because of the lack of rain and virtually non-existent snowpack, which is a crucial part of maintaining the state's water reserves.
It's going to take 18 to 21 (or more) inches of rain over the next six months to alleviate the drought conditions in the worst-hit parts of the west, with gradually lower amounts as you head inland. This data is valid using rainfall current through February, but it's safe to say that the situation hasn't changed very much.
To wrap it up, it's going to be pretty interesting: warmer-than-average for most through the first half of the month, continuing drought in the west, a chance for rain and thunderstorms in the east, and cool (and possibly even a touch snowy) in the Northeast.
Happy April! Let's make this one suck less than those in years past.
[Images: author, Tropical Tidbits, NCDC]