085
FXUS21 KWNC 111900
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 11 2023
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FAVORED TO PERSIST OVER THE SOUTHERN AND
WESTERN CONTIGUOUS U.S. (CONUS) CONTINUING ELEVATED POTENTIAL FOR EXCESSIVE
HEAT ACROSS THESE REGIONS, EXTENDING INTO THE MID-ATLANTIC, FROM WEEK-1 THROUGH
WEEK-2. POSSIBLE FLOODING IS ANTICIPATED TO CONTINUE FOR THE JAMES RIVER IN
NORTHEASTERN SOUTH DAKOTA, WHERE RIVER LEVELS ARE EXPECTED TO REMAIN HIGH
LEADING UP TO AND DURING WEEK-2. CONVERSELY, ABNORMALLY DRY CONDITIONS OVER
PORTIONS OF EASTERN TEXAS AND CENTRAL LOUISIANA INCREASES THE RISK OF RAPID
ONSET DROUGHT (ROD).
HAZARDS
HIGH RISK OF EXCESSIVE HEAT FOR PORTIONS OF NEW MEXICO, ARIZONA, AND WESTERN
TEXAS, WED-THU, JUL 19-20.
MODERATE RISK OF EXCESSIVE HEAT FOR MOST OF THE SOUTHWESTERN CONUS AND PARTS OF
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY, WED-FRI, JUL 19-21.
MODERATE RISK OF EXCESSIVE HEAT FOR CENTRAL AND SOUTHERN FLORIDA, WED-FRI, JUL
19-21.
SLIGHT RISK OF EXCESSIVE HEAT FOR MUCH OF THE WESTERN AND SOUTHERN CONUS AND
MID-ATLANTIC, WED-TUE, JUL 19-25.
FLOODING POSSIBLE FOR PORTIONS OF NORTHEASTERN SOUTH DAKOTA.
RAPID ONSET DROUGHT RISK ACROSS PORTIONS OF EASTERN TEXAS AND CENTRAL LOUISIANA.
DETAILED SUMMARY
FOR FRIDAY JULY 14 - TUESDAY JULY 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JULY 19 - TUESDAY JULY 25: THE GEFS, ECMWF, AND CMCE ENSEMBLE
MEANS INDICATE SLIGHTLY STRONGER RIDGING ACROSS THE WESTERN AND SOUTHERN CONUS
COMPARED TO YESTERDAY, WITH POSITIVE 500-HPA HEIGHT ANOMALIES IN EXCESS OF 596
DM CENTERED OVER THE FOUR CORNERS AND SOUTHERN PLAINS. A HIGH RISK OF EXCESSIVE
HEAT IS DESIGNATED FOR A SMALLER REGION THAN YESTERDAY, FOR PARTS OF NEW
MEXICO, ARIZONA, AND WESTERN TEXAS, JUL 19 TO 20, WHERE THE GEFS AND ECMWF
PROBABILISTIC EXTREMES TOOLS (PETS) SHOW AT LEAST A 60% CHANCE OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH PERCENTILE OF THE HISTORICAL DISTRIBUTION. A
MODERATE RISK (>40% CHANCE) IS POSTED FOR PARTS OF THE SOUTHWESTERN CONUS,
SOUTHERN PLAINS, AND LOWER MISSISSIPPI VALLEY, JUL 19 TO 21 AND IS ALSO
SLIGHTLY DECREASED IN COVERAGE ACROSS THE WESTERN EXTENT. A BROAD SLIGHT RISK
OF EXCESSIVE HEAT CONTINUES TO BE HIGHLIGHTED ACROSS THE WESTERN AND SOUTHERN
CONUS AND MID-ATLANTIC THROUGHOUT WEEK-2 BASED ON WHERE THE GEFS AND ECMWF PETS
INDICATE AT LEAST A 20% CHANCE OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH
PERCENTILE. THE NATIONAL BLEND OF MODELS (NBM) SHOWS THE POTENTIAL FOR NEAR
RECORD BREAKING MAXIMUM TEMPERATURES EXCEEDING 103 DEG F ACROSS THE FOUR
CORNERS AT THE BEGINNING OF THE PERIOD. FURTHER EAST, THE NBM INDICATES THE
POTENTIAL FOR RECORD BREAKING MAXIMUM TEMPERATURES IN THE UPPER 90S (DEG F)
ACROSS SOUTHERN TEXAS, LOUISIANA, AND FLORIDA AT THE BEGINNING OF THE PERIOD
AND RECORD HIGH LOW TEMPERATURES PRIMARILY IN THE UPPER 70S. RELATIVELY HIGH
HUMIDITY IS EXPECTED TO SUPPORT HIGH HEAT INDEX VALUES IN THESE REGIONS. THERE
IS LESS SPATIAL COVERAGE IN THE NBM OF ANTICIPATED NEAR RECORD TEMPERATURES
COMPARED TO YESTERDAY WHICH MAY SIGNAL SOME APPEASEMENT IN THE HEAT LEVELS.
ANTICIPATED HOT, DRY CONDITIONS ACROSS THE SOUTHWESTERN CONUS AND SOUTHERN
PLAINS MAY SUPPORT ENHANCED WILDFIRE RISK, ESPECIALLY WHERE THE NATIONAL
INTERAGENCY FIRE CENTER (NIFC) SHOWS A MODERATE RISK OF SIGNIFICANT FIRE
POTENTIAL AND HIGH RISK TRIGGERS BY THE END OF WEEK-1.
THE ELEVATED RISK OF DROUGHT DEVELOPMENT IS CONTINUED FOR PARTS OF EAST TEXAS
AND LOUISIANA, DUE TO RECENT (IN SOME CASES RECORD) HEAT IN RECENT WEEKS AND
EXPECTED EXCESSIVE HEAT FORECAST TO PERSIST THROUGH MUCH OF THE WEEK-2 PERIOD.
IN ADDITION, INCREASED CHANCES OF BELOW-NORMAL PRECIPITATION IS FORECAST FOR
THESE SAME AREAS FOR WEEK-2. AS SUCH, A RISK OF RAPID ONSET DROUGHT (ROD) IS
MAINTAINED FOR MUCH OF EASTERN TEXAS AND CENTRAL LOUISIANA.
RECENT HEAVY RAINFALL HAS RESULTED IN A CONTINUATION OF ELEVATED STREAM FLOWS
ALONG THE JAMES RIVER IN NORTHEASTERN SOUTH DAKOTA, LEADING TO AN INCREASED
RISK OF FLOODING DURING WEEK-2 FOR SOME LOCATIONS ALONG THAT BASIN. THE
NATIONAL WEATHER SERVICE (NWS) 5-DAY SIGNIFICANT FLOOD OUTLOOK POTENTIAL
INDICATES FLOODING OVER VERMONT AND LIKELY FLOODING ACROSS PARTS OF
MASSACHUSETTS AND CONNECTICUT, WHICH IS LIKELY TO CONTINUE THROUGH WEEK-1 AND
POTENTIALLY INTO AT LEAST PART OF WEEK-2. THE WEATHER PREDICTION CENTER'S (WPC)
7-DAY WEEK-1 PRECIPITATION OUTLOOK INDICATES ANTICIPATED HEAVY RAINFALL FOR
THESE AREAS AND THE CLIMATE PREDICTION CENTER'S (CPC) WEEK-2 OUTLOOK FAVORS LOW
PROBABILITIES OF ABOVE NORMAL PRECIPITATION. DUE TO UNCERTAINTY REGARDING THIS
FLOODING POTENTIAL A RISK AREA FOR WEEK-2 IS NOT DESIGNATED FOR NEW ENGLAND AT
THIS TIME BUT WILL BE MONITORED IN THE UPCOMING DAYS.
THERE IS MULTI-MODEL DEPICTION OF INGREDIENTS THAT ARE CONDUCIVE FOR THE
SOUTHWEST MONSOON ACROSS PORTIONS OF THE FOUR CORNERS INCLUDING FAVORABLE
POSITIONING OF THE MID-LEVEL RIDGE OVER THE FOUR CORNERS AND ENHANCED MOISTURE.
THE ECMWF AND CANADIAN PETS SHOW AT LEAST A 20% CHANCE OF 3-DAY RAINFALL IN
THIS REGION EXCEEDING THE 85TH PERCENTILE CLIMATOLOGICALLY, WITH THE GEFS NOT
INDICATING THESE SIGNALS AND LIMITING ENHANCED RAINFALL FURTHER SOUTH OVER
MEXICO. THERE IS TOO MUCH MODEL UNCERTAINTY REGARDING THE SPECIFICS OF WHERE
THE HEAVIEST PRECIPITATION IS ANTICIPATED BUT WILL BE MONITORED IN THE UPCOMING
DAYS.
AN AREA OF CONVECTION SOUTHWEST OF MEXICO IN THE EAST PACIFIC IS ANTICIPATED TO
BECOME A TROPICAL STORM (INVEST 94E) LATER TODAY. THIS DISTURBANCE HAS THE
POSSIBILITY OF TRACKING WESTWARD INTO THE CENTRAL PACIFIC AND APPROACHING THE
HAWAIIAN ISLANDS BY THE START OF WEEK-2, WHICH COULD BRING ENHANCED
PRECIPITATION AND HIGH WINDS TO SOME AREAS OF THE ISLANDS. THE PETS HINTS AT
THIS POTENTIAL FOR HEAVY PRECIPITATION, SHOWING AT LEAST A 20% CHANCE OF 3-DAY
ACCUMULATED PRECIPITATION EXCEEDING THE 85TH PERCENTILE NEAR OR OVER THE STATE.
NO HAZARDS ARE POSTED FOR ALASKA. HOWEVER, PARTS OF THE YUKON FLATS CONTINUE TO
DRY OUT, WITH SOME LOCATIONS ALREADY FALLING INTO ABNORMAL DRYNESS AND MODERATE
DROUGHT (ACCORDING TO THE U.S. DROUGHT MONITOR). THE ECMWF AND CANADIAN PETS
ALSO INDICATE AT LEAST A 20% CHANCE OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE ACROSS THESE SAME AREAS DURING WEEK-2. THE ONGOING
DRYNESS, COUPLED WITH THE POTENTIAL FOR ABOVE-NORMAL TEMPERATURES, IS
ANTICIPATED TO ELEVATE FIRE CONCERNS FOR PARTS OF THE STATE ESPECIALLY ACROSS
EASTERN PORTIONS WHERE THE NIFC INDICATES A MODERATE RISK OF SIGNIFICANT FIRE
POTENTIAL BY THE END OF WEEK-1.
FORECASTER: MELISSA OU
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