Following The Current And Future Temperature Extremes

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Highlight: Central heat wave breaks (slowly). Southeast Brazil peak cold tomorrow morning. FLASH: North Africa to Russia heat wave.


Fig. 1: Current NOAA/NWS weather watch, warning and advisory areas. Annotated is hottest maximum temperature in the Great Plains heat wave and cold front timing ending the heat wave. Emerging Northwest heat also included.

Great Plains heat wave discussion: Central U.S. Crop Areas continue to experience extreme heat. Heat Advisories are posted for South Dakota/southern Minnesota to Louisiana/Mississippi/Alabama (Fig. 1). The hottest days of the heat wave generally feature maximum temperatures at or above 100F. Based on the ECM, ending of the heat wave is after today from Pierre, SD to Des Moines, IA. The cold front SLOWLY shifts south waiting until late Saturday to reach central Kansas and not until next Monday to shift south into northern Louisiana. Hot extremes (95-100F) are also likely into the East ahead of this cold front and an Extreme Heat Watch has been posted over the fire-parched interior Northwest. July ends with plenty of extreme heat in the U.S.

The much cooler transition that follows the heat wave is accompanied by somewhat isolated streaks of heavy rains. The first streak of rain is across the Iowa/Missouri border where up to 3 in. of rain is possible Saturday (Fig. 2). A second streak of heavy rain (1-3 in.) is forecast for next Monday across the southern Great Plains (Fig. 3). Elsewhere, rain is somewhat sparse during the cool transition.

Fig. 2-3: ECM (heavy) streaks of rainfall forecast for late week and early next week during the cooler pattern change ahead.

Fig. 4-5: North-central U.S. heat and widespread dryness in the 8-14-day forecast.

While the Midwest U.S. cools this weekend/early next week, the tendency is for the cooler weather to shift southward. Consequently, extreme heat rebuilds quickly across Canadian Prairies and the North-central U.S. (Fig. 4). Widespread dryness will accompany the returning excessive heat (Fig. 5).

Southeast Brazil freeze: The GFS Day 1-5 temperature anomaly forecast is dramatically cold into Southeast Brazil (Fig. 6). The peak cold occurs tomorrow morning when a widespread -1C to -6C freeze occurs for interior southeast Brazil (Fig. 7). The cold conditions begin this morning and repeat Friday morning but tomorrow is the most widespread cold. Moderating temperatures steadily follow for the weekend and next week. Despite the temperature extremes (cold now and quite warm days 11-15) the 15-day rainfall outlook is mostly dry.

Fig. 6-7: GFS 5-day temperature anomaly forecast for South America and the peak cold morning for southeast Brazil (tomorrow).

Fig. 8-9: The GFS indicates a North Africa to Southern Russia heat wave set-up during the medium-range.

North Africa to Southwest Russia heat wave: During the 6-10/11-15-day period (Fig. 8-9), the GFS indicates a worse-case scenario regarding potential excessive heat in Southeast Europe to West-central Russia. The super-hot climate across North Africa amplifies and surges northeastward into an upper ridge position across the Caspian Sea region. As a result, maximum temperatures surge into the 100’s for parts of the Russia corn, soybean and wheat zones beginning MON/TUE of next week. Southeast Europe fire hazards increase, rapidly drying soils in-between Black and Caspian Sea and north and east of Caspian Sea emerge.