There’s a tie-in with the mammoth hot air dome—the most expanded air mass to date this summer—and a tropical system arriving in California at tropical storm strength Sunday into Monday. The heat dome is forecast to develop over the nation’s mid-section late this weekend into next week
Daytime satellite view of HURRICANE HILARY off the west coast of Mexico Thursday 
Here’s Hurricane Hilary Thursday as viewed by GOES EAST 
Several additional Thursday satellite view of Hurricane Hilary off Mexico–this one from GOES WEST 
One of several clusters of track forecast off hurricane/tropical cyclone forecast models of Hurricane Hilary’s future movement toward and into California and Nevada. 
The NWS GEFS model Hurricane Hilary track forecasts 
The European Centre’s ensemble model forecast tracks 
Here’s more on the potential flooding tropical rains which may occur there and how the mammoth hot air dome predicted to bring Chicago heat and humidity later this weekend into early next is impacting the tropical system’s movement:
Ocean temps are abnormally warm off Mexico’s west coast. Tropical systems feed on the moisture and latest heat energy these warm ocean waters provide. But it’s a powerful southerly steering flow aloft on the backside of the MAMMOTH HOT AIR DOME predicted to bring Chicago heat and humidity later this weekend into next week that are to guide Hurricane Hilary’s remnants—currently (as of Thursday morning) more than 1,000 mile south/southeast of the Golden State—which may guide the hurricane’s remnant torrential rains in the deserts of the Southwest and into California and Nevada.
The RISK OF EXCESSIVE RAINFALL in coming days 
The NWS Weather Prediction Center’s (WPC) TOTAL RAINFALL forecast from a blend of computer forecast models 
FLASH FLOOD WATCHES are out across a wide swath of the Southwest in anticipation of potential torrential downpours with “Hilary”–which may reach California this weekend as a rare tropical storm 
This is a CIMSS satellite derived analysis of PRECIPITABLE WATER Thursday across a region which included Hurricane Hilary late Thursday 
Color enhanced satellite view of Hurricane Hilary over the Pacific west of Mexico–a storm expected to intensity to a strong CAT 4 hurricane with 140 mph sustained winds before heading north and encountering cooler ocean waters off Baja California. It’s at that point the storm’s winds will weaken. But Hilary is predicted to head north and possibly landfall in southern California as a TROPICAL STORM. If that happens, its would be the first tropical storm to reach California since the “Long Beach Tropical Storms of 1939—-84 years ago. See less 
Closer look at the atmospheric water content with Hurricane Hilary late Thursday 
Projected model atmospheric moisture levels are predicted to be 3 to 4 times normal as the system reaches the Southwest. This could unleash torrential rains capable of producing flooding on the region—a region which includes Phoenix, Tuscon, San Diego, Los Angeles and even potentially Las Vegas and Reno, NV.
Developing hot dome to build into the Plains and Midwest this weekend and into next week; vast area of steering winds around this hot dome is to latch onto “Hurricane Hilary” off Mexico pulling wind, waves and potentially heavy rains into California
- “Hilary” could reach California as a rare “Tropical Storm” (sustained winds of 39+ mph) this weekend.
- Potentially California’s first landfalling Tropical Storm since the “Long Beach Tropical Storm Of 1939″—84 Years Ago.
- Flash Flood Watches are out as hot, humid air prepares to build into Chicago.
The mammoth dome of hot air predicted to build over the central U.S., including the Midwest, is to bring the Chicago area a run of hot, humid weather with inland 90s Sunday through Wednesday, shutting down rain in the process. Though the hot air mass is to produce 90s in the Chicago area, easterly winds off Lake Michigan may temper the heat a bit along Lake Michigan Sunday and Monday. The ENTIRE AREA is in for a run of high humidity which, combined with inland thermometer readings in the 90s, threatens triple-digit heat indices. ADVISORIES for heat may become necessary later this weekend into next week.
THE MAMMOTH EXPANDED DOME OF HOT AIR taking shape is shown on a whole series of model forecasts from a variety of meteorological centers which generate model forecasts of the weather. What’s fascinating is the unanimity among the forecasts. This is the Monday upper air forecast off the NWS’ GFS deterministic mode 
Here’s Environment Canada’s GEM model forecast of the HOT DOME for MONDAY 
The UKMET Monday upper air forecast 
Here’s the Japanese Meteorological Agency’s Monday upper air forecast 
The German ICON model Monday forecast 
The Korean model forecast for Monday 
The European Centre’s Monday upper air forecast
SMOKY SKIES FRIDAY
Fires burning in the record heat of recent days in the West are sending smoke eastward on upper steering winds. Skies over Chicago will reflect the movement of that smoke into our airspace. Computer model smoke projections indicate denser smoke will lend skies a “hazy/smoky” look Friday—smoke which will thin some on Saturday.
The locations of fires in the Western U.S. and across sections of Canada are indicated by the icons superimposed on satellite imagery of the eastbound smoke as it appeared Thursday. 
The smoke is VERY APPARENT on this Thursday afternoon GOES EAST weather satellite image. 
Highlighted smoke on this GOES EAST image.
