US Forecast Little Changed; Another Tropical System in the Atlantic to be Followed?: Wet south, and dry elsewhere describes the 10 day Central US forecast. The EU and GFS models are in good agreement, and though there are some discrepancies with respect to another Gulf tropical storm that is forming in the Atlantic the Ridge/Trough pattern looks to hold across the US.
The track of this next Atlantic tropical storm will be closely monitored heading into the long Labor Day weekend. Whether this storm heads south of Florida or curves north into the Atlantic missing the US will key the US weather pattern beyond September 12th.
The map reflects an experimental high resolution Drought Trigger Tool which looks at rainfall/temps and tries to measure developing pockets of dryness.
The 60 day SPI map notes that 40% of the Midwest endured drier than normal weather and rapidly drying soils. The impact of the dryness on Midwest crop yields will be determined during upcoming harvest. The dryness is much different than recent crop years. And the N Plains and Midwest dryness trend looks to persist into the middle of September with just limited rainfall via a NW Upper air flow.
The forecast has been surprisingly consistent for North America with a Ridge/ Trough (R/T) pattern to be maintained. This R/T long wave pattern arrived in early August and has been constant every since. The NW upper air flow has closed the flow of Gulf moisture northward and produced the 7th coolest August on record for the Central US. These cool temps will persist across the eastern half of the US for another 10 days. The graphic reflects the GFS Ensemble model forecast into September 9th. Notice the large area of mostly dry weather that is located over the western 2/3’s of the US with any rains in the south and east produced from the remains of Hurricane Harvey. That storm appears to be speeding its pace to the NE and it will show up across E KY by late in the weekend.
The extended North American weather pattern will be strongly influenced by the development of another system in the Gulf and a more important system that has become tropical storm Irma in the Atlantic. The path of Irma will determine if the current R/T pattern is maintained? This storm needs to be closely monitored.