980
FXUS01 KWBC 171820
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 PM EDT MON JUL 17 2023
VALID 00Z TUE JUL 18 2023 - 00Z THU JUL 20 2023
...LENGTHY HEAT WAVE TO CONTINUE IN THE SOUTHWEST, SOUTH CENTRAL
U.S., AND SOUTH FLORIDA...
..TROPICAL STORM CALVIN WEAKENING ON APPROACH TO HAWAI'I
HEAVY
RAINS EXPECTED...
...CANADIAN WILDFIRES/SMOKE RESPONSIBLE FOR AIR QUALITY ALERTS
OVER PARTS OF THE NORTHERN HIGH PLAINS, MIDWEST, GREAT LAKES, AND
NORTHEAST...
THE UPPER LEVEL RIDGE OF HIGH PRESSURE RESPONSIBLE FOR THE HEAT
WAVE IN THE WEST WILL EXPAND ACROSS THE SOUTHWEST AND GULF COAST
STATES THROUGH MID-WEEK. RECORD BREAKING HEAT IS EXPECTED IN THE
FOUR CORNERS STATES, TEXAS TO THE LOWER MISSISSIPPI VALLEY, AND
SOUTH FLORIDA EACH DAY. DAYTIME HIGHS WILL ROUTINELY RESIDE IN
THE TRIPLE DIGITS IN THE DESERT SOUTHWEST AND TEXAS. THE GULF
COAST AND MID-SOUTH CAN EXPECT DAYTIME HIGHS IN THE MID-UPPER 90S
THAT COINCIDE WITH OPPRESSIVELY HIGH DEW POINTS, RESULTING IN
SWELTERING HEAT INDICES BETWEEN 105-115F. DAILY LOW TEMPERATURES
WILL REMAIN QUITE WARM, BREAKING RECORD WARM DAILY MINIMUMS IN
SOME AREAS, ALLOWING FOR MINIMAL RELIEF FROM THE HEAT OVERNIGHT.
AN EXPANSIVE AREA OF EXCESSIVE HEAT WARNINGS AND HEAT ADVISORIES
REMAINS IN THE SOUTHWEST, SOUTHERN PLAINS, WESTERN GULF COAST, AND
EVEN PARTS OF SOUTH FLORIDA WHERE THE AIR-SEA INTERACTION IS
LEADING TO A FEEDBACK LOOP BETWEEN THE AIR AND WATER TEMPERATURES
DUE TO THE LIGHTER THAN AVERAGE WIND FLOW. PLEASE VISIT HEAT.GOV
FOR MORE INFORMATION ON IMPACTS FROM THE HEAT WAVE. THE NORTHEAST
AND MID-ATLANTIC WILL CONTINUE TO SEE HOT AND HUMID CONDITIONS
THROUGH TUESDAY, DESPITE THE RECENT PASSAGE OF A WEAK COLD FRONT.
TO THE WEST, A STRONGER COLD FRONT WILL PROVIDE THE MIDWEST AND
GREAT LAKES WITH COOLER THAN NORMAL TEMPERATURES. SOME LOCATIONS
IN THE UPPER MIDWEST WILL STRUGGLE TO GET OUT OF THE 70S FOR HIGHS
ON TUESDAY.
IN THE NORTH-CENTRAL PACIFIC OCEAN, TROPICAL STORM CALVIN WILL
CONTINUE TO WEAKEN AS IT APPROACHES THE ISLAND OF HAWAI'I, WHERE
TROPICAL STORM WATCHES ARE IN EFFECT -- LATE TUESDAY INTO
WEDNESDAY, WITH THE SYSTEM BECOMING A TROPICAL DEPRESSION LATER ON
WEDNESDAY. THE SYSTEM SHOULD LEAD TO LOCALLY HEAVY RAINFALL, AS
MUCH AS 4-7 INCHES ON WINDWARD SLOPES, AS IT PASSES BY THE 50TH
STATE. ROUGH SEAS ARE ALSO POSSIBLE. SEE CENTRAL PACIFIC
HURRICANE CENTER ADVISORIES ON CALVIN FOR MORE INFORMATION ON THE
STORM.
BACK IN THE LOWER 48, NUMEROUS SHOWERS AND THUNDERSTORMS WILL
ENGULF PORTIONS OF THE MIDWEST AND MUCH OF THE EAST ON TUESDAY AND
WEDNESDAY. ON TUESDAY, THE THREAT FOR HEAVY AND EXCESSIVE RAINFALL
BECOME HEIGHTENED OVER THE NORTHEAST AS A COLD FRONT APPROACHES
FROM THE WEST. ON TUESDAY AND WEDNESDAY, PORTIONS OF THE OHIO
VALLEY HAVE HEIGHTENED RISKS OF EXCESSIVE RAINFALL, WITH THE BEST
CHANCE OF SEVERE WEATHER NEAR THE ILLINOIS/MISSOURI BORDER ON
TUESDAY PER STORM PREDICTION CENTER OUTLOOKS, WITH LOWER CHANCES
IN THE PLAINS AND OHIO VALLEY ON WEDNESDAY. FOR EXACT THREAT
LEVELS AND RELATED DISCUSSIONS, SEE WPC EXCESSIVE RAINFALL
OUTLOOKS AND SPC CONVECTIVE OUTLOOKS.
CANADA'S HAS WITNESSED THEIR MOST EXTENSIVE WILDFIRES ON RECORD IN
2023 BASED ON AREA BURNED; AN AREA APPROACHING THE SIZE OF
KENTUCKY. SMOKE FROM THE CANADIAN WILDFIRES WILL REMAIN IN THE
PICTURE THROUGH TUESDAY AS NORTHWESTERLY WINDS ALOFT THAT
ORIGINATE FROM CANADA CONTINUE TO DIRECT SMOKE INTO THE LOWER 48.
THERE ARE AIR QUALITY ALERTS ISSUED FOR AREAS THE INCLUDE THE
NORTHERN HIGH PLAINS, THE MIDWEST, GREAT LAKES, CENTRAL TENNESSEE
AND NORTH CAROLINA, AND INTO THE NORTHEAST WHERE HIGHER
CONCENTRATIONS OF SMOKE WILL RESULT IN UNHEALTHY AIR QUALITY FOR
SENSITIVE GROUPS. SMOKE CONCENTRATIONS SHOULD DIMINISH OVER PARTS
OF THE HEARTLAND ON TUESDAY, BUT MAY STILL CAUSE POOR AIR QUALITY
ALONG THE EAST COAST.
ROTH/MULLINAX
GRAPHICS AVAILABLE AT
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP
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