145
FXUS21 KWNC 231958
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 23 2024
SYNOPSIS: COAST-TO-COAST MID-LEVEL HIGH PRESSURE IS PREDICTED ACROSS THE LOWER
48 STATES DURING WEEK-2. THIS CORRESPONDS TO A SUBSTANTIAL INCREASE IN THE
PREDICTED MAGNITUDE AND SPATIAL COVERAGE OF HEAT SIGNALS COMPARED TO YESTERDAY.
IN ALASKA, MID-LEVEL LOW PRESSURE IS FORECASTED ACROSS MOST OF THE STATE, WITH
THE EXCEPTION OF THE ALEUTIAN ARCHIPELAGO WHERE MID-LEVEL HIGH PRESSURE IS
FAVORED.
HAZARDS
HIGH RISK OF EXCESSIVE HEAT FOR THE SOUTH-CENTRAL PLAINS AND ADJACENT PORTIONS
OF THE MISSISSIPPI VALLEY, WED-SUN, JUL 31-AUG 4.
MODERATE RISK OF EXCESSIVE HEAT FOR THE NORTHEAST AND MID-ATLANTIC REGION,
WED-TUE, JUL 31-AUG 6.
MODERATE RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE INTERIOR WEST, ALL BUT FAR
SOUTHERN PORTIONS OF THE GREAT PLAINS, AND CENTRAL PORTIONS OF THE MISSISSIPPI
VALLEY, WED-TUE, JUL 31-AUG 6.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE INTERIOR WEST, MOST OF THE GREAT PLAINS,
MOST OF THE MISSISSIPPI AND OHIO VALLEYS, THE GREAT LAKES REGION, NORTHEAST,
AND MID-ATLANTIC, WED-TUE, JUL 31-AUG 6.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE CENTRAL VALLEY OF CALIFORNIA, THU-TUE,
AUG 1-6.
RAPID ONSET DROUGHT RISK FOR PORTIONS OF THE NORTHERN AND CENTRAL PLAINS.
DETAILED SUMMARY
FOR FRIDAY JULY 26 - TUESDAY JULY 30:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JULY 31 - TUESDAY AUGUST 06: FOR THE WEEK-2 PERIOD, ENSEMBLE
MEANS FAVOR ANOMALOUS MID-LEVEL RIDGING AND ACCOMPANYING POSITIVE HEIGHT
DEPARTURES ACROSS THE CONTIGUOUS U.S. (CONUS), WITH MAXIMUM 500-HPA HEIGHTS OF
AT LEAST 594 DM ACROSS THE SOUTHWESTERN AND SOUTH-CENTRAL STATES.
THE WEEK-2 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES OVER ALMOST ALL
OF THE CONUS. A SLIGHT RISK OF EXCESSIVE HEAT IS DEPICTED ACROSS MOST OF THE
LOWER 48 STATES OUTSIDE OF THE SOUTHEAST AND SOUTHERN TEXAS, AND VALID FOR THE
ENTIRE OUTLOOK PERIOD. WITHIN THIS EXTENSIVE SLIGHT RISK AREA, THERE ARE TWO
AREAS WHERE A MODERATE RISK OF EXCESSIVE HEAT IS FAVORED. ONE AREA INCLUDES THE
NORTHEAST AND MUCH OF THE MID-ATLANTIC REGION, VALID JUL 31-AUG 6. THE SECOND,
LARGER AREA INCLUDES MUCH OF THE INTERIOR WEST, MOST OF THE GREAT PLAINS, AND
CENTRAL SECTIONS OF THE MISSISSIPPI VALLEY, JUL 31-AUG 6. WITHIN THIS SECOND,
LARGER AREA, THERE IS A HIGH RISK OF EXCESSIVE HEAT FOR THE SOUTH-CENTRAL
PLAINS AND ADJACENT PARTS OF THE MISSISSIPPI VALLEY, VALID JUL 31-AUG 4. A
GENERAL CONSENSUS OF TEMPERATURE AND EXCESSIVE HEAT GUIDANCE INDICATES ACTUAL
AIR TEMPERATURES ACROSS PORTIONS OF THE NORTHEAST AND MID-ATLANTIC REGION MAY
REACH WELL INTO THE 90’S, WITH HEAT INDEX VALUES EXCEEDING 100 DEG F. FOR THE
PLAINS, MAXIMUM AIR TEMPERATURES OF 100-105 DEG F ARE EXPECTED, WITH HEAT INDEX
VALUES SURPASSING 110 DEG F OVER PORTIONS OF THE SOUTH-CENTRAL PLAINS. A SKILL
WEIGHTED, BIAS-CORRECTED HYBRID TOOL (WHICH CONSIDERS ACTUAL AIR TEMPERATURE
AND HEAT INDEX), RAW TEMPERATURES FROM THE ENSEMBLE MEANS, AND PROBABILISTIC
EXTREMES TOOL (PET) TEMPERATURES WERE USED IN THE CONSTRUCTION OF TODAY’S
EXCESSIVE HEAT MAP. BASED ON THESE SAME OBJECTIVE TOOLS, A SLIGHT RISK OF
EXCESSIVE HEAT IS DEPICTED FOR THE CENTRAL VALLEY OF CALIFORNIA, AUG 1-6, WHERE
HEAT INDEX VALUES MAY APPROACH OR EXCEED 110 DEG F.
ACROSS THE SOUTHWEST, THE SUBTROPICAL RIDGE AXIS IS PREDICTED TO SHIFT SLIGHTLY
SOUTHWARD DURING WEEK-2. THIS PATTERN IS TYPICALLY ASSOCIATED WITH
SIGNIFICANTLY DRIER CONDITIONS FROM ABOUT NORTHERN ARIZONA AND NORTHERN NEW
MEXICO NORTHWARD. HOWEVER, TROPICAL MOISTURE FROM THE EASTERN PACIFIC IS
INDICATED BY SOME MODELS TO REACH SOUTHERN ARIZONA AND SOUTHERN NEW MEXICO
DURING WEEK-2, BUT AT THIS TIME PRECIPITATION AMOUNTS ARE FAVORED TO BE BELOW
0.5-INCH AND NO CORRESPONDING PRECIPITATION HAZARD IS POSTED AT THIS TIME.
THE HEAVIEST PRECIPITATION AMOUNTS PREDICTED DURING THIS OUTLOOK PERIOD RANGE
FROM 1.0-1.5 INCHES OVER A 3-DAY PERIOD, FOCUSED ALONG THE SOUTHEAST AND GULF
COASTS. HOWEVER, NORMAL WEEKLY PRECIPITATION AMOUNTS FOR THOSE AREAS RANGE FROM
1.0-1.5 INCHES IN MOST AREAS TO ALMOST 2 INCHES ALONG THE GULF COAST OF
FLORIDA. THEREFORE, NO PRECIPITATION HAZARDS ARE DEPICTED ON TODAY’S HAZARDS
MAP. HOWEVER, ACCORDING TO THE EXPERIMENTAL FLOOD HAZARD OUTLOOK, THIS AMOUNT
OF PRECIPITATION IS ENOUGH TO RENEW FLOODING CHANCES ACROSS THE EASTERN COASTAL
REGION OF NORTH CAROLINA, WHICH RECENTLY EXPERIENCED HEAVY PRECIPITATION AND
HAS ELEVATED SOIL MOISTURE ANOMALIES.
THE COMBINATION OF CONTINUED ABOVE-NORMAL TEMPERATURES AND BELOW-NORMAL
PRECIPITATION SUPPORTS THE CONTINUATION OF A RAPID ONSET DROUGHT (ROD) RISK
OVER MANY PARTS OF THE NORTHERN AND CENTRAL HIGH PLAINS. DRY SOILS, STRESSED
VEGETATION, AND REDUCED WATER AVAILABILITY DUE TO LOW PONDS AND STREAMS MAY
LEAD TO INCREASED IMPACTS TO AGRICULTURE AND LIVESTOCK, WITH SOME LOCATIONS
ALREADY EXPERIENCING IMPACTS.
NO HAZARDS ARE POSTED FOR ALASKA DURING WEEK-2. HOWEVER, THERE IS A SIGNIFICANT
CHANCE OF ACCUMULATING SNOW FOR PORTIONS OF THE CENTRAL AND EASTERN BROOKS
RANGE, WHICH COULD IMPACT TRAVEL ON THE DALTON HIGHWAY. THIS POSSIBILITY WILL
BE REASSESSED TOMORROW AFTER LOOKING AT THE MOST RECENT MODEL SOLUTIONS. NEAR
JUNEAU, LOCALIZED FLOODING MAY BE A CONCERN ASSOCIATED WITH THE GLACIAL
OUTBURST FLOOD FOR THE MENDENHALL RIVER.
FORECASTER: ANTHONY ARTUSA
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