Dynamics of Tropical Cyclone Idai
03/24/2019, 1:28 pm EDTOn Again/Off Again El Nino
04/08/2019, 1:17 pm EDTSelected Cities MAY-SEP 2019 % of 30-Year Normal CDD Forecast
Soil Moisture Ahead of Warm Season Suppresses Summer Heat
Discussion: The preliminary Climate Impact Company 2019 MAY-SEP percent of normal 30-year CDD forecast is (nationally) 102.8% of normal (Table 1). The value is considered marginally above normal. Last year a whopping 126.3% of normal was observed. One of the leading catalysts to the less warm forecast compared to last year is soil moisture. Note the increasing dry-to-drought zone across the U.S. last April to June (Fig. 1-2) compared to excessive wet soils as March 2019 ends (Fig. 3). Dry soils foreshadow anomalous hot summer heat ahead while wet soils suppress excessive heat potential.
Fig. 1-2: Last April and June dry soil moisture across the Southwest expanded and eventually contributed to an exceptionally hot summer nationally.
Fig. 3: Soil moisture ranking based on 1895-2019 climatology is at record wet levels in the Central and East U.S.
The warmest city forecasts for MAY-SEP 2019 include Seattle (124% of the 30-year normal) and Portland (113%) trailed by Boston and Burbank (each 108%). Seattle was the hot spot last warm season. The cool spots for MAY-SEP 2019 include Salt Lake City (74% of the 30-year normal) to Minneapolis (88%) plus Des Moines and Kansas City (each 96%).
| %Normal | My-Se Vs. 30-yr | %Normal | My-Se Vs. 30-yr | ||
| 2019 Fcst | 2019 Class | 2018 Verif | 2018 Class | ||
| 108% | Above | BOS-Boston | 136% | Much Above | |
| 109% | Above | BDL-Hartford | 130% | Much Above | |
| 105% | Above | LGA-LaGuardia | 123% | Much Above | |
| 105% | Above | PHL-Philadelphia | 110% | Much Above | |
| 105% | Above | BWI-Baltimore | 119% | Much Above | |
| 106% | Above | DCA-Washington | 120% | Much Above | |
| 106% | Above | RIC-Richmond | 122% | Much Above | |
| 104% | Above | ORF-Norfolk | 126% | Much Above | |
| 103% | Normal | ATL-Atlanta | 120% | Much Above | |
| 102% | Normal | CMH-Columbus | 133% | Much Above | |
| 104% | Above | CLE-Cleveland | 149% | Much Above | |
| 101% | Normal | CVG-Cincinnati | 138% | Much Above | |
| 98% | Normal | ORD-Chicago | 142% | Much Above | |
| 96% | Below | DSM-Des Moines | 131% | Much Above | |
| 96% | Below | MCI-Kansas City | 126% | Much Above | |
| 105% | Above | DFW-Dallas | 111% | Much Above | |
| 104% | Above | IAH-Houston | 110% | Much Above | |
| 101% | Normal | DNR/DEN-Denver | 130% | Much Above | |
| 74% | Much Below | SLC-Salt Lake City | 120% | Much Above | |
| 103% | Normal | LAS-Las Vegas | 117% | Much Above | |
| 124% | Much Above | SEA-Seattle | 178% | Much Above | |
| 113% | Much Above | PDX-Portland | 143% | Much Above | |
| 103% | Normal | SAC-Sacramento | 97% | Normal | |
| 108% | Above | BUR-Burbank | 115% | Much Above | |
| 102% | Normal | PHX-Phoenix | 105% | Above | |
| 88% | Much Below | MSP-Minneapolis | 139% | Much Above | |
| 99% | Normal | DTW-Detroit | 133% | Much Above | |
| 106% | Above | FAT-Fresno | 113% | Much Above | |
| 102.8% | Normal | National | 126.3% | Much Above | |
Table 1: Climate Impact Company May to September forecast of percent of normal 30-year HDD by city and compared to 2018. 97 to 103 percent of normal is NORMAL; 103-109 percent (91-97 percent) is ABOVE (BELOW) normal. >109% is MUCH ABOVE normal. <91% is MUCH BELOW normal.