Despite Stronger +PNA/-NAO Forecast, Stratospheric Cooling Over Canada Keeps North America Warm!

Climate Impact Company Midday Update

Issued: Friday October 30, 2026

Highlight: Despite stronger +PNA/-NAO pattern during the medium range, the cold stratosphere across Canada motivates warm surface temperatures.

Fig. 1-2: The 12Z GFS U.S. medium range temperature anomalies.

Discussion: NOAA/CPC -AO/-NAO both dip to near -1.0 from this morning qualifying as moderate-strength intensity and about twice as strong as yesterday. The PNA pattern is buoyantly positive. On their own, these climate signals indicate support for a West ridge/East trough during the medium range. The 2-week MJO forecast indicates moderate intensity in phase_2 which is a cool East U.S. signature. Previously, progression to phase_3 was indicated which is a warm signal for the U.S. EPO/WPO are relatively flat suggesting the ridge potential is in the West and trough in the East.

At midday, the 12Z GFS is BOLDLY warm in the 6-10-day period (Fig. 1). The extremely warm signature is in response to a cold stratosphere aligned across Canada. The stratosphere stays cold across Canada in the 11-15-day period maintaining a warm signature across North America at ground level (Fig. 2).

Table 1: The midday 12Z GFS U.S. gas population weight HDD forecast into middle November.