058
FXUS02 KWBC 261911
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
310 PM EDT MON JUN 26 2023
VALID 12Z THU JUN 29 2023 - 12Z MON JUL 03 2023
...MAJOR HEAT WAVE EXPANDS FROM TEXAS THROUGH THE MID-LOWER
MISSISSIPPI VALLEY REST OF THIS WEEK BEFORE PIVOTING TO SOUTHEAST
THIS WEEKEND...
..HEAVY WAVE DEVELOPS OVER DESERT SOUTHWEST THIS WEEKEND
...EXCESSIVE RAINFALL THREAT EXPANDS FROM THE CENTRAL PLAINS
THROUGH THE OHIO VALLEY LATE WEEK...
..OVERVIEW WITH GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
A WESTERN U.S. TROUGH BEGINS A SLOW EASTERN EJECTION THURSDAY,
LIFTING THROUGH THE MIDWEST INTO EASTERN CANADA THIS WEEKEND WHILE
TROUGHING OVER THE NORTHEAST LIFTS OUT FRIDAY. THE WPC FORECAST
FROM THROUGH MONDAY WAS PRIMARILY DERIVED WELL CLUSTERED
DETERMINISTIC GUIDANCE, THE 06Z GFS AND THE 00Z ECMWF/CMC/UKMET
THROUGH SATURDAY AND THEN INCLUDED MORE 06Z GEFS AND 00Z ECENS FOR
SUNDAY AND MONDAY.
..WEATHER/HAZARDS HIGHLIGHTS
AN AMPLIFIED TROUGH SLOWLY PROGRESSING THROUGH THE NORTHEAST
THURSDAY WILL WRAP ATLANTIC MOISTURE AROUND A GRADUALLY WEAKENING
LOW PRESSURE SYSTEM TO FUEL WIDESPREAD AND LINGERING
PRECIPITATION. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH
POTENTIAL TRAINING AND EMBEDDED THUNDERSTORMS (ESPECIALLY INTO
FAVORED TERRAIN) IN THIS SLOW-TO-EXIT SYSTEM. A MARGINAL RISK OF
EXCESSIVE RAIN IS MAINTAINED OVER NEW ENGLAND TO THE ADIRONDACKS
THURSDAY/THURSDAY NIGHT IN AN AREA WITH ANTECEDENT RAINFALL FROM A
PREVIOUS SLOW-MOVING SYSTEM. ADDITIONAL LOW PRESSURE AND ENHANCED
RAINS WITH THE REMNANTS OF CINDY IS EXPECTED TO PASS TO THE EAST
FRIDAY/SATURDAY TOWARD THE CANADIAN MARITIMES.
MEANWHILE, THE EJECTION OF UPPER TROUGH ENERGIES OUT FROM THE
WEST/ROCKIES LATER WEEK IS EXPECTED TO BRING SCATTERED SHOWERS AND
STRONG TO SEVERE STORM CHANCES OUT ACROSS THE CENTRAL PLAINS ALONG
WITH LOCALLY HEAVY RAINFALL THURSDAY NIGHT THROUGH FRIDAY NIGHT. A
MARGINAL RISK OF EXCESSIVE RAINFALL IS IN EFFECT FOR
THURSDAY/THURSDAY NIGHT FOR THE CENTRAL HIGH PLAINS THROUGH
CENTRAL NEBRASKA THURSDAY AND FRIDAY GIVEN HEIGHT
FALLS/INSTABILITY AND POTENTIAL FOR REPEAT/TRAINING OF CELLS NORTH
OF A DEVELOPING WARM FRONT. THIS FRONTAL WAVE EXPANDS EAST FRIDAY,
WARRANTING AN EXPANSION OF THE MARGINAL RISK EAST FROM THE CENTRAL
PLAINS ACROSS THE MIDWEST TO THE CENTRAL APPALACHIANS FOR
FRIDAY/FRIDAY NIGHT.
THE HEAVY RAIN FOCUS THEN SHIFTS EAST AND SOUTHEAST THIS WEEKEND
AHEAD OF THE FURTHER DEVELOPING FRONTAL WAVE.
EXCESSIVE HEAT WILL CONTINUE TO PLAGUE THE SOUTHERN PLAINS AND
EXPAND NORTH AND EAST THIS WEEKEND TO PORTIONS OF THE CENTRAL
PLAINS AND THE MID-LOWER MISSISSIPPI VALLEY. THE HEAT WILL BE
OPPRESSIVE WITH WIDESPREAD HIGH TEMPERATURES EXCEEDING 100 DEGREES
AND HEAT INDICES AS HIGH AS 120 DEGREES. HEAT INDICES MAY EVEN
EXCEED 120 DEGREES IN SOME LOCATIONS IN SOUTH TEXAS. TENS OF HIGH
TEMPERATURE RECORDS ARE IN DANGER OF BEING BROKEN DURING THIS
SIGNIFICANT HEAT WAVE. THE DESERT SOUTHWEST WILL ALSO EXPERIENCE A
NOTABLE HEATING THIS WEEKEND WITH MAX TEMPS 5 TO 10 DEGREES ABOVE
NORMAL WHICH MEANS 110 TO 115 DEGREES MAX TEMPS FOR THESE HOT
ENVIRONS SOUTH FROM LAS VEGAS AND WEST FROM PHOENIX.
JACKSON
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND
KEY MESSAGES ARE AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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