Issued: 12am on Thursday, January 1st 1970
Technical Forecast Discussion
Short Term (Wednesday 9/18 through Saturday 9/21)
Previously projected and discussed ridge has finally lifted its upper axis over the northern Great Lakes. In conjunction, this vastly amplified flow across the United States has been widely influenced by a deepening trough along the west coast. Additionally, upper troughing is positioned over the western Atlantic and the northeastern U.S coast, which has set up a subtle ‘Omega Blocking’ pattern for the eastern and southeastern United States. In response, surface high pressure will gradually slide southward along the Appalachians with readings increasing between 1021mb-1028mb. This strong subsidence will remain in place throughout the short term as high pressure and increased 500mb heights maintain control… Wednesday night and throughout the remainder of the term, a consistent diurnal pattern will be in place. As the previously mentioned higher pressure begins to slide southward and overhead, low-level flow will begin to veer from the east and eventually SW’ly into Saturday. Temperatures will stay unseasonably warm with highs in the low 80s, but begin to gradually increase into the mid-80s as the weekend approaches. Simultaneously, moisture values will remain pleasantly low as dewpoints stay well below the 60-degree mark. Although, low-level moisture will be on the rise for late Sunday and early long term as the aforementioned upper disturbance and associated cold front begins its approach.
Long Term (Sunday 9/22 through Tuesday 9/24)
Fairly high pressure ~1024mb lingers just south of the region influencing a strong SW’ly flow. Warm and above average temperatures continue as the mid-80s is likely for Sunday. This heavily discussed ridging pattern will begin to break down as this shortwave from the west propagates NE’ly over the upper Great Plains and eventually north of the Great Lakes. A moderately intense jet streak (upwards of 130 knots) positions itself NE’ly upstream of this trough by Sunday morning, housing the strengthening surface low within the left exit region. Simultaneously, a moderately strong W-E jet establishes over the central U.S and emerges a secondary surface low over eastern Nebraska, which coordinates with the southward extending cold front. Low-level moisture will begin to increase from W-E Sunday night as the frontal boundary advances on the region. Precipitation chances will increase overnight on Sunday and into Monday morning as the frontal passage is likely sometime Monday evening. High pressure once again builds in with this passage and slightly reduces temperatures into the upper 70s for midweek.
