Cold Front Stalls – Drenches Mid-south and Tennessee Valley Mid-to-late Week!

Fig. 1: NOAA/NWS U.S. weather watch, warning and advisory areas.

Discussion: The Northwest U.S. braces for a super-hot week. Maximum temperature forecasts for Portland to Seattle are in the 97-100F range for tomorrow while Interior Washington crests at 105-110F mid-to-late week. Consequently, Excessive Heat Warnings are issued for Washington into Oregon (Fig. 1). The excessive heat eases near the coast later this week but continues interior sections through next weekend.

Heat Advisories linger one more day ahead of a severe weather outbreak in the Northeast Corridor today. New Jersey/Delaware and eastern Massachusetts remain in a Heat Advisory. Currently, a Tornado Watch is issued for Western Pennsylvania. HRRR radar depiction forecast indicates peak of severe weather later today is around 5PM as a broken squall line extends from Virginia to Maine featuring primarily damaging wind gusts (Fig. 2). The cold front triggering the severe weather in the Northeast Corridor today settles into the Mid-south U.S. and eastward to North Carolina and stalls mid-to-late week and weekend. The result is a strong-to-severe thunderstorm pattern featuring excessive rain along this boundary (Fig. 3). Arkansas and Tennessee may receive >5 in. of rain from this lengthy event! In the latest U.S. population weight CDD forecast the national outlook remains hot with not much change in the consensus of all forecast models for this week and next week (Fig. 4). However, the Aug. 5-11 forecast trends hotter lead by the GFS ENS.

Fig. 2: HRRR radar depiction forecast for 5PM across the Northeast Corridor.

Fig. 3: GFS 120-hour forecast of heavy rainfall from the southern Great Plains to the Carolinas midweek through next weekend.

Fig. 4: U.S. population weight CDD forecast utilizing all models, their consensus and comparing with 24 hours ago and the 30-year/10-year normal.