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FXUS21 KWNC 121928
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 12 2024
SYNOPSIS: A HEAT WAVE IS FORECAST TO BE ONGOING ACROSS PORTIONS OF THE MIDWEST,
MID-ATLANTIC, AND NORTHEAST AS WELL AS MUCH OF THE INTERIOR WEST AT THE OUTSET
OF WEEK-2 ASSOCIATED WITH BROAD MID-LEVEL HIGH PRESSURE OVER THE CENTRAL AND
EASTERN CONTIGUOUS U.S.(CONUS). BY THE MIDDLE OF THE PERIOD, THIS FEATURE IS
FORECAST TO BROADEN FURTHER, SPREADING EXCESSIVE HEAT CHANCES INTO THE
CALIFORNIA CENTRAL VALLEY. ENHANCED SOUTHERLY FLOW AND AN INFLUX OF TROPICAL
MOISTURE FAVOR ELEVATED CHANCES OF HEAVY PRECIPITATION AND POTENTIAL FLOODING
NEAR THE GULF OF MEXICO COAST, ALTHOUGH THERE IS UNCERTAINTY REGARDING TIMING
AND COVERAGE OF THE HEAVIEST PRECIPITATION.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE MIDWEST, THU-MON, JUN
20-24.
MODERATE RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE NORTHEAST AND
MID-ATLANTIC, THU-FRI, JUN 20-21.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND EASTERN CONUS,
THU-WED, JUN 20-26.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE INTERIOR WEST, THU-WED,
JUN 20-26.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS THE SOUTHERN CENTRAL VALLEY OF CALIFORNIA,
SAT-WED, JUN 22-26.
MODERATE RISK OF HEAVY PRECIPITATION ALONG THE WESTERN GULF OF MEXICO COAST,
THU-SUN, JUN 20-23.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE WESTERN AND CENTRAL GULF OF MEXICO
COAST, THU-WED, JUN 20-26.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE CENTRAL AND EASTERN GULF OF MEXICO
COAST, THU-MON, JUN 20-24.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY, THU-MON, JUN 20-24.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE ROCKIES, AND THE CENTRAL AND
SOUTHERN PLAINS, THU-MON, JUN 20-24.
FLOODING POSSIBLE ACROSS PORTIONS OF THE GULF OF MEXICO COAST.
DETAILED SUMMARY
FOR SATURDAY JUNE 15 - WEDNESDAY JUNE 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY JUNE 20 - WEDNESDAY JUNE 26: TODAY’S ENSEMBLE SOLUTIONS FROM THE
GEFS AND ECMWF ARE SHOWING GOOD CONTINUITY WITH YESTERDAY PARTICULARLY WITH
REGARD TO THE MID-LEVEL RIDGE CENTERED OVER THE EASTERN CONUS AT THE OUTSET OF
WEEK-2. THE ECMWF IS ESPECIALLY BULLISH, WITH A 594DM MAXIMUM ON DAY 8 OVER THE
TENNESSEE VALLEY, SETTING THE STAGE FOR CONTINUED CHANCES FOR EXCESSIVE HEAT TO
AFFECT MUCH OF THE CONUS DURING THE FORECAST PERIOD. GUIDANCE FROM THE GEFS AND
ECMWF PROBABILISTIC EXTREMES TOOLS (PETS) CONTINUE TO DEPICT AT LEAST A 40%
PROBABILITY OF DAILY MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE FOR
PORTIONS OF THE NORTHEAST, MID-ATLANTIC, AND MIDWEST DURING JUN 20-21. BY
DAY-10 THE RIDGE FLATTENS SLIGHTLY, DROPPING HEIGHTS OVER THE EAST COAST,
SUBSEQUENTLY ALSO LOWERING PROBABILITIES OF EXCESSIVE HEAT; HOWEVER THE 40%
THRESHOLD CONTINUES TO BE MET OVER THE MIDWEST THROUGH THE 24TH. THEREFORE, A
MODERATE RISK FOR EXCESSIVE HEAT IS POSTED FOR PORTIONS OF THE MID-ATLANTIC AND
NORTHEAST FOR JUN 20-21, AND FOR PORTIONS OF THE MIDWEST FOR JUN 20-24. BOTH
THE GEFS AND ECWMF PETS BOTH ALSO INDICATE AT LEAST A 20% PROBABILITY OF DAILY
MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE FOR A BROADER AREA OF THE
CENTRAL AND EASTERN CONUS FOR THE WHOLE WEEK-2 PERIOD, ENCOMPASSING MUCH OF THE
TENNESSEE VALLEY AND MICHIGAN, AS WELL AS GREATER COVERAGE FOR THE MID-ATLANTIC
AND NORTHEAST RELATIVE TO THE MODERATE RISK DESCRIBED ABOVE. MUCH OF THE
INTERIOR WEST IS ALSO INFLUENCED BY THIS BROAD RIDGE, WHICH IS ALSO INDICATED
BY THE PETS. AT THE OUTSET OF WEEK-2 A WEAK TROUGH OVER THE WEST COAST REDUCES
THE CHANCES FOR EXCESSIVE HEAT OVER CALIFORNIA, BUT BY DAY-10 THE COMBINATION
OF A WEAKENING TROUGH IN THE WEST AND A BROADENING RIDGE OVER THE EAST RESULT
IN IN AN ENHANCEMENT OF CHANCES FOR EXCESSIVE HEAT FOR THE SOUTHERN CENTRAL
VALLEY OF CALIFORNIA. THEREFORE, A SLIGHT RISK FOR EXCESSIVE HEAT IS POSTED FOR
ALL OF WEEK-2 FOR MUCH OF THE INTERIOR WEST, AND FOR JUN 22-26 FOR THE SOUTHERN
CENTRAL VALLEY.
IN ADDITION TO THE WIDESPREAD POTENTIAL FOR EXCESSIVE HEAT FOR LARGE PORTIONS
OF THE CONUS, ENSEMBLE SOLUTIONS CONTINUE TO DEPICT AN INCREASE IN TROPICAL
MOISTURE AND CONVECTIVE ACTIVITY OVER THE SOUTHERN GULF OF MEXICO LATE IN
WEEK-1 AND CONTINUING INTO WEEK-2. TODAY’S SOLUTIONS CONFINE THE HEAVIEST
PRECIPITATION FURTHER WEST RELATIVE TO YESTERDAY, BUT CONTINUE TO FAVOR
POTENTIALLY HEAVY PRECIPITATION FOR MUCH OF THE GULF COAST. THE GEFS AND ECMWF
PETS DEPICT AT LEAST A 20% PROBABILITY OF 3-DAY PRECIPITATION TOTALS TO EXCEED
THE 85TH PERCENTILE AND AT LEAST ONE INCH FOR MUCH OF THE GULF COAST THROUGHOUT
WEEK-2, WITH HIGHER PROBABILITIES AND THE POTENTIAL FOR EXCEEDING 2 INCHES
EARLY IN THE FORECAST PERIOD. THEREFORE A MODERATE RISK FOR HEAVY PRECIPITATION
IS POSTED FOR PORTIONS OF THE WESTERN AND CENTRAL GULF COAST FOR JUN 20-23, AND
A SLIGHT RISK FOR HEAVY PRECIPITATION EXTENDING FURTHER INLAND FOR THE WHOLE
WEEK-2 PERIOD. MODEL SOLUTIONS DEPICT WIDESPREAD PRECIPITATION COVERING MUCH OF
THE GULF COAST AT THE OUTSET OF THE FORECAST PERIOD, THEN CONFINING THE
HEAVIEST PRECIPITATION WEST OF THE MISSISSIPPI DELTA AFTER THE 24TH. THEREFORE,
A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR PORTIONS OF THE CENTRAL AND
EASTERN GULF COAST FOR JUN 20-24. FINALLY, ABUNDANT ANTECEDENT RAINFALL OVER
MUCH OF EASTERN TEXAS HAS RESULTED IN MOST OF THE AREA RESERVOIRS AT OR NEAR
CAPACITY. GIVEN THE POTENTIAL FOR HEAVY RAINFALL DURING WEEK-2, A RISK FOR
POSSIBLE FLOODING IS ALSO HIGHLIGHTED FOR PORTIONS OF EASTERN TEXAS AND
SOUTHWEST LOUISIANA.
THE WEAK TROUGH OVER THE WEST COAST MENTIONED EARLIER IS ALSO FAVORED TO
INTRODUCE SOME INSTABILITY DOWNSTREAM OVER THE NORTHERN TIER, WHICH PAIRED WITH
PASSING SHORTWAVE DISTURBANCES PROVIDE THE POTENTIAL FOR PERIODS OF HEAVY
PRECIPITATION FOR PORTIONS OF THE UPPER MIDWEST THROUGHOUT WEEK-2 AND
PARTICULARLY THROUGH THE MIDDLE OF THE PERIOD. THIS IS WELL-INDICATED BY THE
ECMWF (AND TO A LESSER EXTENT THE GEFS) PETS, WHICH DEPICT AT LEAST A 20%
PROBABILITY OF 3-DAY PRECIPITATION TO EXCEED THE 85TH PERCENTILE AND 1 INCH FOR
JUN 20-24, THEREFORE A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR
PORTIONS OF THE UPPER MIDWEST AND UPPER MISSISSIPPI VALLEY FOR DATES INDICATED
ABOVE. THE SYNOPTIC PATTERN ALSO FAVORS ENHANCED WINDS ALONG THE EASTERN
ROCKIES AND WESTERN GREAT PLAINS. THE ECMWF AND GEFS BOTH INDICATE HIGH
PROBABILITIES (>60%) OF WIND SPEEDS TO REACH AT LEAST 10KT, AND THE ECMWF
WIND-GUST FORECAST DEPICTS SIMILAR PROBABILITIES FOR GUSTS GETTING AS HIGH AS
34KT, ALSO FOR THE EARLY AND MIDDLE PORTIONS OF THE FORECAST PERIOD. THEREFORE
A SLIGHT RISK FOR HIGH WINDS IS POSTED FOR PORTIONS OF THE EASTERN ROCKIES AND
WESTERN PLAINS FOR JUN 20-24.
FORECASTER: DANNY BARANDIARAN
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