1:45 PM | ***Significant tropical moisture a growing threat for SoCal and other parts of the SW US…building heat across central US…nice overall weather pattern continues for NE US***
Paul Dorian
A tropical system now over the eastern Pacific Ocean is going to intensify significantly likely reaching hurricane status (“Hilary”) and it may threaten southern California and other parts of the SW US with high winds and excessive rainfall amounts from later this weekend into early next week. Map courtesy weathermodels.com (Dr. Ryan Maue), NOAA
Overview
We have entered the second half of August and this is typically when tropical activity ramps up in the Atlantic Basin. Indeed, there are a couple of impressive waves to watch in the far eastern Atlantic Ocean and there may be a threat to deal with in the eastern US/Gulf of Mexico by the last week of August; however, of more immediate concern is the current activity in the eastern Pacific Ocean. There is a growing chance that significant moisture from a tropical system makes its way into the Southwest US by later this weekend and early next week - and this includes a very real threat for excessive rainfall across southern California. In addition, winds may become quite high depending on the ultimate storm track that this developing tropical system undertakes.
Elsewhere, a building ridge of high pressure in the upper part of the atmosphere will result in an intensifying heat wave by this weekend across the central states and it is likely to expand to the Great Lakes and Midwest. While the heat may ultimately expand all the way into the Mid-Atlantic/Northeast US, this would be just a one or two day affair and the overall weather pattern for the northeastern states remains quite favorable for very comfortable air masses to reach this area from central Canada.
Excessive rainfall amounts are on the table in the Southwest US later this weekend and early next week and this risk zone includes southern California. Not only will tropical moisture likely inundate the SW US, monsoonal seasonal winds will enhance the moisture content as well. Map courtesy weathermodels.com (Dr. Ryan Maue), NOAA
Details
A strong tropical wave moved over the continent of Africa in recent days and it is now nearing its west coast and a second system has already traveled west to the open waters of the far eastern Atlantic Ocean. Both of these systems can ultimately intensify into named tropical storm status and either can threaten the eastern US/Gulf of Mexico by the time we get to the last week of August. This increasing tropical activity in the Atlantic Basin is not too surprising given the fact that this is the time of year “climatologically-speaking” for the “ramping up” of activity.
A tropical system now well off the coast of Mexico will intensify in coming days and may very well impact southern California and other portions of the Southwest US later this weekend into early next week with significant rainfall and possibly high winds. Map courtesy tropicaltidbits.com (Dr. Levi Cowan), NOAA
Meanwhile, there is also tropical activity in the eastern Pacific Ocean and one of these systems now known officially as “Invest EP90” may very well have a major impact on the Southwest US from later this weekend into early next week and this risk zone region includes southern California. A pretty well organized area of showers and thunderstorms shows signs of intensification and this tropical system has a great chance of reaching named tropical storm and then hurricane status – would be “Hilary” - as it moves roughly parallel to the coast of southwestern Mexico during the next few days. After that, this system may push northwestward to a position near or over the southwestern part of California. Whether or not this system actually does push over land, there is the very real chance that copious amounts of moisture will flow northward into southern California and other sections of the Southwest US including Arizona and Nevada. To make matters worse, monsoonal seasonal winds may very well enhance the moisture levels in the SW US both during the tropical storm and later next week following its departure. In addition to the threat for excessive rainfall, damaging wind gusts are on the table in the SW US early next week depending on the ultimate storm track…stay tuned.
High pressure ridging will intensify by this weekend over the central states and it will result in a hot stretch of weather from the Plains to the Great Lakes and Midwest. Map courtesy NOAA, tropicaltidbits.com
Apart from the tropical scene, one of the big weather stories in coming days will be a building heat wave for much of the central US as high pressure riding intensifies in the upper part of the atmosphere. The hotter-than-normal weather will likely extend eastward for a few days across the Great Lakes and Midwest and eventually even make an eastward excursion all the way into the Mid-Atlantic region by early next week. The overall weather pattern, however, continues to look quite favorable in the Mid-Atlantic region and Northeast US for additional comfortable air masses to reach into this area so any hot spell would be rather short-lived. One such comfortable air mass arrives in the Mid-Atlantic region and Northeast US on Friday following the passage of a cool front and it should stay quite comfortable on Saturday before the short-lived hotter weather early next week. Another strong cold front likely arrives in the Northeast US on Monday night paving the way for more comfortable conditions next Tuesday and Wednesday.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
Follow us on Facebook, Twitter, YouTube
Video discussion: