097
FXUS02 KWBC 162039
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
438 PM EDT FRI JUN 16 2023
VALID 12Z MON JUN 19 2023 - 12Z FRI JUN 23 2023
...HAZARDOUS HEAT IS LIKELY ACROSS TEXAS AND LOUISIANA WITH SOME
RECORD TEMPERATURES POSSIBLE THROUGH NEXT WEEK...
..OVERVIEW
A FAIRLY STAGNANT PATTERN WILL ONCE AGAIN BE IN PLACE FOR THE
MEDIUM RANGE PERIOD NEXT WEEK, WITH AN UPPER RIDGE/HIGH NEAR THE
RIO GRANDE THAT WILL PRODUCE EXCESSIVE HEAT ACROSS THE
SOUTH-CENTRAL CONUS. THE UPPER RIDGE SHOULD EXTEND TO THE
NORTHEAST NEAR THE MIDWEST/GREAT LAKES, WHILE AN UPPER LOW LOOKS
TO BE ATOP THE SOUTHEAST/TENNESSEE VALLEY FOR A POTENTIAL REX
BLOCK PATTERN. THE UPPER LOW ALONG WITH AMPLE MOISTURE IS LIKELY
TO PRODUCE HEAVY TO EXCESSIVE RAIN ACROSS THOSE REGIONS. MEANWHILE
IN THE WEST, PERSISTENT TROUGHING WILL LEAD TO COOLER THAN NORMAL
TEMPERATURES AND SOME PRECIPITATION IN THE NORTHWEST SHIFTING INTO
THE PLAINS WITH TIME, WITH AN EVENTUAL HEAVY RAINFALL THREAT
POSSIBLE HERE AS WELL.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE HAS CONTINUED TO GENERALLY BE IN GOOD AGREEMENT
WITH THE OVERALL PATTERN DURING MOST OF THE MEDIUM-RANGE PERIOD
THE LAST FEW DAYS, WITH THE MAIN FEATURES ACCOUNTED FOR AND MORE
SUBTLE DIFFERENCES IN THEIR STRENGTH/PLACEMENT. AN OMEGA-LIKE
BLOCKY NORTHERN STREAM PATTERN CONTINUES WITH MEAN TROUGHING OVER
THE EAST, RIDING OVER THE CENTRAL CONUS, AND A TROUGH OVER THE
WEST. MEANWHILE, AN ENERGETIC SOUTHERN STREAM REMAINS IN PLACE
OVER THE SOUTH, WITH A RIDGE CENTERED OVER EASTERN PORTIONS OF THE
SOUTHWEST AND TEXAS, AND AN UPPER-LEVEL LOW DEVELOPING OVER THE
SOUTHEAST, EXPECTED TO REMAIN IN THE REGION THROUGH AT LEAST THE
MIDDLE OF THE FORECAST PERIOD. OVER TIME THE RIDGING OVER THE
CENTRAL CONUS EXTENDS NORTHWARD INTO SOUTHEASTERN CANADA, SETTING
UP A BIT OF A REX BLOCK PATTERN FOR THE EAST. THE WESTERN
UPPER-LEVEL TROUGH TENDS TO RETROGRADE TO THE WEST AS HEIGHTS RISE
A BIT OVER THE WESTERN PLAINS TOWARDS THE END OF THE PERIOD.
THE 00Z CMC TENDED TO BE A BIT OF AN OUTLIER COMPARED TO THE OTHER
GUIDANCE, PARTICULARLY WITH RESPECT TO THE EVOLUTION OF THE
PATTERN OVER THE CENTRAL AND EASTERN CONUS. THE UPPER-LEVEL LOW
OVER THE SOUTHEAST EARLY IN THE PERIOD IS STRONGER WHILE THE
SOUTHERN STREAM RIDGE, AND THE GENERAL MEAN NORTHERN STREAM
RIDGING OVER THE CENTRAL CONUS, TENDS TO BE A BIT WEAKER THROUGH
THE MID- TO LATE PERIOD. THE 00Z UKMET IS SIMILARLY A BIT WEAKER
WITH THE NORTHERN EXTENT OF THIS RIDGE, BUT MORE IN LINE WITH THE
LATEST RUNS OF THE GFS/ECMWF. IN TERMS OF PREDICTABILITY, THERE
ALSO LOOKS TO BE A BIT LESS RUN-TO-RUN CONSISTENCY IN THE GFS AND
ECMWF WITH RESPECT TO THE PATTERN IN THIS SAME REGION COMPARED TO
THE LAST COUPLE OF DAYS, WITH THE STRENGTH OF THE CUTOFF LOW AND
RIDGE VARYING A BIT IN PRIOR RUNS, THOUGH THE LATEST 00Z/06Z GFS
AND 00Z ECMWF ARE AT LEAST CONSISTENT WITH EACH OTHER. UNCERTAINTY
IN THE PATTERN INCREASES AT THE END OF THE PERIOD, WITH THE
00Z/06Z GFS DEPICTING THE CUTOFF LOW OVER THE SOUTHEASTERN U.S.
BEGINNING TO RETROGRADE WESTWARD ALONG THE GULF COAST AS THE
ENERGY SPLITS IN IN THE 00Z ECMWF, WITH SOME RETROGRADING WESTWARD
SIMILAR TO THE GFS BUT WITH AN UPPER-LEVEL LOW RETAINED
NORTHEASTWARD OVER THE MID-ATLANTIC. THE PREDICTABILITY OF THE
PATTERN IN THIS REGION REMAINS LOW AS WELL, WITH EARLIER RUNS OF
THE GFS SHOWING THE CUTOFF LOW DEEPENING OVER THE MIDWEST/GREAT
LAKES WHILE WEAKENING IN THE ECMWF. THE 00Z CMC REMAINS A LARGER
OUTLIER COMPARED TO THE MOST RECENT GUIDANCE, WITH A MUCH DEEPER
CUTOFF LOW HOVERING OVER THE EASTERN CONUS.
A GENERAL MODEL BLEND IS USED FOR THE UPDATED WPC FORECAST, WITH
MORE WEIGHT GIVEN TO THE 00Z ECMWF/06Z GFS OVER THE 00Z UKMET, AND
THE 00Z CMC IN PARTICULAR, GIVEN INCREASING DIVERGENCE FROM THE
CLUSTERING TOWARDS THE 00Z ECMWF/06Z GFS SOLUTION. THE 00Z ECENS
MEAN TENDED TO MORE CLOSELY AGREE WITH THE DETERMINISTIC GUIDANCE
IN THE STRENGTH OF THE FEATURES OVER THE CENTRAL/EASTERN CONUS IN
THE MID-PERIOD, THUS A CONTRIBUTION FROM THE 00Z ECENS IS ADDED
FOLLOWING THE REMOVAL OF THE FORECAST TIME-LIMITED UKMET. THE 00Z
GEFS MEAN SIMILARLY RETAINS A BIT MORE DETAIL IN THE LATE-PERIOD,
AND A CONTRIBUTION IS ADDED WHILE REMOVING THE 00Z CMC GIVEN THE
INCREASING DIVERGENCE IN THE PATTERN OVER THE CENTRAL/EASTERN
CONUS COMPARED TO THE 00Z ECMWF/06Z GFS. THE INITIAL FORECAST
BLEND IS SIMILAR TO THE PRIOR WPC FORECAST THROUGH THE EARLY TO
MID- FORECAST PERIOD. HOWEVER, THE DIVERGING TRENDS IN THE
GUIDANCE LED TO A WEAKER UPPER-LOW IN THE EAST WHILE RETAINING
MORE UPPER-LEVEL RIDGING TO THE NORTH IN A REX BLOCK PATTERN
COMPARED TO THE PRIOR FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
THE UPPER LOW MEANDERING OVER THE TENNESSEE VALLEY OR SO, ALONG
WITH A MEANDERING FRONTAL SYSTEM AND AMPLE GULF MOISTURE, WILL
PROVIDE SUPPORT FOR MULTIPLE ROUNDS OF RAIN AND THUNDERSTORMS FOR
THE SOUTHEASTERN QUADRANT OF THE COUNTRY THROUGH MUCH OF NEXT
WEEK. SLIGHT RISKS OF EXCESSIVE RAINFALL ARE IN PLACE FOR BOTH
MONDAY AND TUESDAY IN THE SOUTHEAST TO SOUTHERN APPALACHIANS (WITH
A SLIGHT SHIFT EASTWARD TUESDAY) GIVEN THE POTENTIAL FOR
WIDESPREAD 1-3" TOTALS PER DAY WITH LOCALLY HIGHER AMOUNTS.
PORTIONS OF THIS REGION HAVE OR WILL LIKELY HAVE BY THAT TIME WET
ANTECEDENT CONDITIONS GIVEN RECENT OR UPCOMING EPISODES OF HEAVY
RAINFALL. CONTINUAL ADJUSTMENTS HAVE BEEN MADE TO THE SLIGHT RISK
AREAS GIVEN THIS PRIOR AND ANTICIPATED RAINFALL, INCLUDING
WESTWARD EXTENSIONS OVER PORTIONS OF THE FLORIDA PANHANDLE THAT
HAVE RECENTLY EXPERIENCED EXTREME RAINFALL, AS WELL AS TO THE EAST
INTO NORTHERN FLORIDA ON TUESDAY AS FORECAST RAINFALL AMOUNTS
CONSOLIDATE OVER THE REGION AND OVERLAP EXPECTED RAINFALL ON
MONDAY. AS NEXT WEEK PROGRESSES, THE TRACK OF THE UPPER LOW WILL
AFFECT WHERE RAINFALL SPREADS, BUT THE TREND HAS BEEN TO FOCUS ON
THE SOUTHEAST, WITH THE POTENTIAL TO EXPAND A BIT WESTWARD TOWARDS
THE LOWER MISSISSIPPI VALLEY AS WELL AS INTO SOUTH FLORIDA.
MEANWHILE, TEMPERATURES ACROSS THE REGION ARE LIKELY TO BE BELOW
AVERAGE WITH THE CLOSED LOW OVERHEAD, INFLUENCE OF
CLOUDS/PRECIPITATION, AND COLD-AIR DAMMING SETTING UP ALONG THE
APPALACHIANS.
AS ANOTHER UPPER LOW COMES INTO THE NORTHWEST AND PIVOTS NEXT
WEEK, PRECIPITATION CHANCES WILL INCREASE THERE NEAR AND BEHIND A
FRONTAL SYSTEM MONDAY-TUESDAY. GIVEN THE BELOW NORMAL HEIGHTS AND
THUS TEMPERATURES, THE HIGHEST ELEVATIONS COULD SEE SOME SNOW.
FARTHER EAST INTO THE NORTHERN ROCKIES/HIGH PLAINS, THERE MAY BE
SOME INSTABILITY TO WORK WITH AND PRODUCE STORMS, LEADING TO SOME
POSSIBLY LOCALLY HEAVY RAIN OVER AREAS THAT COULD BE SENSITIVE DUE
TO WELL ABOVE NORMAL RAINFALL OVER THE PAST FEW WEEKS. INTO
TUESDAY AND BEYOND, RAIN AND THUNDERSTORM CHANCES SHOULD BE
INCREASINGLY COMMON OVER PORTIONS OF THE THE NORTHERN AND CENTRAL
PLAINS AS THE LOW PRESSURE/FRONTAL SYSTEM STALLS AND FOCUSES
MOISTURE, WITH THE GREATEST POTENTIAL FOR SOME LOCALLY HEAVY
RAINFALL WEDNESDAY-THURSDAY. THE TROUGHING IN THE WEST WILL ALSO
LEAD TO WELL BELOW NORMAL TEMPERATURES PARTICULARLY FOR HIGHS.
HIGH TEMPERATURES OF 15-25F BELOW AVERAGE IN THE GREAT BASIN COULD
CHALLENGE DAILY RECORDS FOR COOL HIGHS ON MONDAY AND TUESDAY, WITH
LOWS AROUND 10F BELOW NORMAL. TEMPERATURES LOOK TO GRADUALLY
MODERATE CLOSER TO, BUT STILL REMAINING BELOW, NORMAL FOR THE
LATTER HALF OF THE WEEK ACROSS THE WEST.
THE EXCESSIVE HEAT WILL CONTINUE INTO NEXT WEEK ACROSS MUCH OF
TEXAS AND INTO PORTIONS OF LOUISIANA AND NEW MEXICO, WITH
WIDESPREAD 100S AND EVEN SOME 110S ACROSS CENTRAL AND SOUTHERN
PORTIONS OF TEXAS, AND 90S COVERING MUCH OF THE LOWER MISSISSIPPI
VALLEY AND THE CENTRAL PLAINS. MANY DAILY RECORD HIGH TEMPERATURES
ARE POSSIBLE, AND SOME MONTHLY RECORDS MAY EVEN BE CHALLENGED.
HEAT INDICES AS HIGH AS 115-120 DEGREES ARE POSSIBLE FOR PARTS OF
SOUTHERN AND SOUTHEASTERN TEXAS WHERE THE GREATEST COMBINATION OF
HIGH DEWPOINTS AND TEMPERATURES WILL LIKELY EXIST. THE HEAT IS
EXPECTED TO GRADUALLY SHIFT WESTWARD WITH TIME, FOCUSING ON
WESTERN TEXAS TOWARDS THE END OF NEXT WEEK. AS MEAN RIDGING
EXPANDS FURTHER NORTH, ADDITIONAL MUCH ABOVE AVERAGE TEMPERATURES
ARE FORECAST FOR PORTIONS OF THE NORTHERN PLAINS, PARTICULARLY ON
MONDAY-TUESDAY, WITH HIGHS REACHING INTO THE MID- TO UPPER 90S. AS
A REX BLOCK PATTERN SETS UP OVER THE NORTHERN TIER, THE UPPER
MIDWEST INTO THE INTERIOR NORTHEAST CAN EXPECT 80S TO LOW 90S FOR
HIGHS FOR THE LATTER HALF OF THE WEEK, ABOUT 10F ABOVE AVERAGE.
PUTNAM/TATE
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
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE
NORTHERN PLAINS, WED-THU, JUN 21-JUN 22.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE SOUTHERN
MID-ATLANTIC, THE LOWER MISSISSIPPI
VALLEY, THE SOUTHERN APPALACHIANS, AND THE TENNESSEE VALLEY,
MON-WED, JUN 19-JUN 21.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, TUE, JUN 20 AND
THU, JUN22.
- FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE
NORTHERN PLAINS.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN
ROCKIES AND THE NORTHERN GREAT
BASIN.
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN PLAINS.
- EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHEAST, THE LOWER
MISSISSIPPI VALLEY, AND THE SOUTHERN
PLAINS, MON-FRI, JUN 19-JUN 23.
- EXCESSIVE HEAT ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY
AND THE NORTHERN PLAINS, MON-TUE,
JUN 19-JUN 20.
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page