News
08/19/2018, 12:30 pm EDT
This Week (August 19-23): Heavy rain Central to East U.S. Discussion: Severe thunderstorms and 1-2 in. (at least) of rain occur today from Nebraska/Iowa to the Delta region shifting to the Corn Belt tomorrow (Fig. 1). On Tuesday the cold front causing the intense weather sweeps into the eastern Ohio Valley/Mid-Atlantic region. Severe storms will affect rain-soaked Pennsylvania later Tuesday. On WED/THU the Southwest U.S. is wet and some of that rain surges into the North-Central States. A much cooler/drier forecast for Chicago on Wednesday reaching Boston Thursday. Air quality alerts for smoke caused by fires spread from the Northwest U.S./Montana to Minnesota. Fig. 1: The NOAA/WPC 72-hour rainfall forecast is indicated. Climate Impact Medium-range Forecast: Northwest/Northeast warmth. Discussion: GFS/ECM ensembles across on anomalous warmth from the Corn Belt to southeast Canada in the 6-10 day period. Cool temperatures settle into the Northwest. Most of the rain in the 6-10 day period stretches across southern Canada. In the 11-15 day period East warmth early period expands westward (and into the West-Central U.S. late period) while Northwest chill eases mid-to-late period. The GFS is warmer West in the 11-15 day forecast. Fig. 2-3: The Climate Impact day 6-10/11-15 U.S. temperature anomaly forecast is indicated. Models: Medium-range favors widening Central/East warmth. Madden Julian oscillation (MJO) is forecast to rampage on in phase 4 offering more excessive rains to India, Southeast Asia and increase in West Pacific tropical cyclone activity. The influence on the U.S. pattern is a mean ridge in the Gulf of Alaska, weak trough in the western U.S. and a ridge pattern that can affect the Central or East U.S. (or both). ECM and GFS ensembles are in general agreement of widening warmth for the eastern half of the U.S. while the West is temperate. The SSTA pattern favors this regime with a cooler character off the U.S. West Coast/Baja California while east of the Northeast/Mid-Atlantic States is bold warm. Tropics: ALL CLEAR continues. The North Atlantic tropics remain quiet although operational models indicate an attempt at some organizing tropical waves in the 6-10 day period. Gas Population Weight CDD 4-Week Forecast: Warmer-than-normal. The bulk of the influence on the 4-week forecast is warming across the eastern half of the U.S. Fig. 4: The Climate Impact 4-week observation/forecast gas population weight CDD forecast for the U.S.
08/19/2018, 12:21 pm EDT
Cooler Climate Pattern Change for California Discussion: Due to tropical cyclone activity up-welling cooler subsurface water a large area of ocean surface west-southwest of Baja California has cooled the past couple weeks (Fig. 1). The cooler SSTA in this region identifies the first cooler-than-normal since late summer 2013. Interestingly, mid-summer was hot in California in 2013 reversing somewhat cooler in AUG/SEP. The cooler ocean surface change was caused by tropical cyclone activity rather than a large-scale climate pattern change so there is questions on how long this cool pattern will last. However, the short-term (next 4 weeks – at least) implications are a climate pattern across California defeating any anomalous heat risk. Model forecasts from last week indicated one more potential extreme heat event in the Los Angeles basin for MON-WED of this week. The forecast has been revised much cooler. Previously, an amplified ridge pattern northeast of Hurricane Lane was projected to give the Los Angeles area another marginal heat wave. However, Lane is moving more due west and will be another hurricane to enter waters south of Hawaii midweek. Mega-clusters indicate the favored upper air pattern 1 and 2 weeks from now indicate a transitional pattern from a North-central U.S. trough to ridge (Fig. 2-3). However, the Southwest U.S. and particularly California is not affected by the ridge pattern(s). Regarding ENSO, a Modoki look has definitely developed. The daily Nino4 SSTA regions which is centered on the Dateline in the equatorial West Pacific is a robust +0.95°C and has warmed 0.58°C in the past 30 days. The Nino3 SSTA region in the eastern equatorial Pacific is right at 0.0°C and has cooled slightly the past 30 days. El Nino Modoki remains a possibility for later 2018. Fig. 1: Daily SSTA analysis of the North Pacific basin yields a cooler changes southwest of Baja California. The cooler change defeats support of the upper ridge pattern causing anomalous heat so far in summer 2018 for that region. Another hurricane is headed for the waters south of Hawaii which are El Nino Modoki-like warm. Fig. 2-3: Mega-clusters preferred upper air patterns on August 24 and August 31 clearly identify California as unaffected.
08/19/2018, 8:22 am EDT
Headline: Severe storms TUE; early autumn feel WED/THU. General forecast… Yesterday: 88/72 Rainfall: 0.06 in. SUN: Mostly cloudy, chance of showers. High 78. Low 65. MON: Mostly cloudy. High 80. Low 68. TUE: Mostly cloudy. Showers and thunderstorms likely. High 82. Low 70. WED: Chance of showers. High 83. Low 60. THU: Partly cloudy. High 77. Low 57. Days 6-10: None. Normal: High 85. Low 64. Operational notes… No alerts SUN/MON. ALERT 2 for wind gust/rainfall TUE. Possible severe weather. Yesterday… Once again, northern service area ONLY affected by heavy rains Radar indicates 2.5 in. near PA/MD border. Breezy! Gust 30-35 was common.