869
FXUS02 KWBC 131855
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT THU JUN 13 2024
VALID 12Z SUN JUN 16 2024 - 12Z THU JUN 20 2024
***EARLY SEASON HEATWAVE FROM THE MIDWEST TO THE EAST COAST, AND
HEAVY RAINFALL BECOMING MORE LIKELY FOR THE WESTERN GULF COAST***
19Z UPDATE: THE EXISTING FORECAST FROM OVERNIGHT DID NOT REQUIRE
MANY CHANGES FOR THE NEW DAY SHIFT FORECAST, AND THE 12Z MODEL
GUIDANCE SUITE IS IN DECENT OVERALL SYNOPTIC SCALE AGREEMENT ON
MOST ASPECTS OF THE MEDIUM RANGE FORECAST. RECENT RUNS OF THE ECMWF
HAVE BEEN HOTTER ACROSS MUCH OF THE EASTERN U.S. FOR THE MIDDLE TO
END OF NEXT WEEK COMPARED TO THE MORE REASONABLE CMC AND GFS
SOLUTIONS, AND WELL ABOVE THE ECENS IN MANY CASES ACROSS THE
NORTHEAST. THE 13Z NBM SERVED AS A GOOD STARTING POINT FOR
TEMPERATURES, AND THIS WAS BLENDED WITH SOME OF THE 6Z GEFS MEAN
WHICH APPEARED TO HAVE THE BEST OVERALL DEPICTION OF THE EXPECTED
HEAT WAVE NEXT WEEK. THE NBM APPEARED A BIT TOO WIDESPREAD WITH
HIGHER QPF TOTALS ACROSS THE CENTRAL/WESTERN GULF COAST REGION, SO
THIS WAS BLENDED WITH SOME OF THE DETERMINISTIC GUIDANCE TO PORTRAY
A MORE REALISTIC LOOKING QPF FORECAST. LITTLE IN THE WAY OF CHANGES
WERE NECESSARY TO THE DAY 4 AND 5 EXCESSIVE RAINFALL OUTLOOKS. THE
PREVIOUS FORECAST DISCUSSION IS APPENDED BELOW FOR REFERENCE.
/HAMRICK
-------------------------------
..GENERAL OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODELS AND ENSEMBLES GENERALLY REMAIN IN GOOD OVERALL
AGREEMENT INTO NEXT WEEK WITH RESPECT TO THE OVERALL PATTERN,
FEATURING A STRONGLY BUILDING UPPER RIDGE ACROSS THE EASTERN HALF
OF THE U.S., AND A DEVELOPING AMPLIFIED UPPER TROUGH OVER THE
WEST. GUIDANCE INDICATES A SOUTHERN STREAM SHORTWAVE OVER THE
SOUTHWEST WILL LIFT NORTHEAST, AND AROUND THE WESTERN PERIPHERY OF
THE BUILDING RIDGE WITH ADDITIONAL EMBEDDED WAVES CROSSING THE
NORTHERN TIER AS THE MAIN UPPER TROUGH BEGINS TO TAKE HOLD OVER THE
WEST. AN UPPER-LEVEL DISTURBANCE NOW OVER FLORIDA SHOULD SLOWLY
WORK WESTWARD OVER THE GULF OF MEXICO THIS WEEKEND INTO NEXT WEEK.
THIS WILL BRING IMPROVING CONDITIONS FOR FLORIDA, WHILE INCREASING
RAINFALL CHANCES FOR THE CENTRAL AND WESTERN GULF COAST AND
VICINITY GOING INTO SUNDAY AND EARLY-MID NEXT WEEK.
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF BEST CLUSTERED GUIDANCE OF THE 18 UTC
GFS/GEFS MEAN AND 18 UTC ECMWF/ECMWF ENSEMBLE MEAN, THE 01 UTC
NATIONAL BLEND OF MODELS THROUGH MEDIUM RANGE TIME SCALES ALL NEXT
WEEK IN A PATTERN WITH NEAR AVERAGE PREDICTABILITY OVERALL.
..WEATHER/HAZARDS HIGHLIGHTS
A MAIN AXIS OF TROPICAL MOISTURE IS FORECAST TO SHIFT WESTWARD
ACROSS THE GULF OF MEXICO AND AFFECT THE CENTRAL TO WESTERN GULF
COAST REGION NEXT WEEK. THE LATEST DAY 4/SUNDAY AND DAY 5/MONDAY
ERO MARGINAL RISK AREAS REMAIN VALID FOR THE WEST-CENTRAL GULF
COAST GIVEN THE MOIST PATTERN. UNCERTAINTY REMAINS, PARTICULARLY
WITH THE POTENTIAL AMOUNT OF RAINFALL AND WITH WESTWARD EXTENT INTO
THE WESTERN GULF INTO LATER NEXT WEEK.
ELSEWHERE, CONVECTIVE PRECIPITATION EVENT IS LIKELY ACROSS AN
UNSTABLE NORTHERN PLAINS AND THE UPPER MIDWEST/WESTERN GREAT LAKES
AS SOUTHERN STREAM TROUGHING EJECTS NORTHEASTWARD FROM THE
SOUTHWEST AS WELL AS LAGGING NORTHERN STREAM UPPER TROUGH APPROACH.
THE MARGINAL RISK AREAS REMAIN IN EFFECT FOR THE UPDATED DAYS 4/5
SUNDAY/MONDAY EXCESSIVE RAINFALL OUTLOOKS. THERE REMAINS A MORE
CONSISTENT SIGNAL THAT THE SUBSEQUENT UPSTREAM APPROACH OF AN
AMPLIFIED UPPER TROUGH OUT FROM THE WEST/NORTHWEST WILL ACT TO ALSO
SUPPORT THE MARGINAL RISK OF HEAVY RAINS OVER THE NORTHERN
ROCKIES/HIGH PLAINS DAY5/MONDAY. THIS FOCUS IS EXPECTED TO SLOWLY
WORK ACROSS THE NORTH-CENTRAL U.S. TUESDAY INTO NEXT THURSDAY AS
AIDED BY RENEWED CYCLO/FRONTOGENESIS.
AS FOR ANOMALOUS TEMPERATURES, AN AMPLIFIED UPPER RIDGE SLATED TO
STEADILY/BROADLY SHIFT FROM THE SOUTHWEST THROUGH THE SOUTH-
CENTRAL U.S. TO THE EAST OVER THE COMING WEEK WILL PRODUCE
WIDESPREAD ANOMALOUS HEAT AND HUMIDITY, WITH THE POTENTIAL FOR SOME
DAILY RECORD HIGHS TO BE ESTABLISHED. TEMPERATURES WILL ALREADY BE
RATHER HOT OVER PORTIONS OF THE SOUTH BEFORE THE EVEN BROADER
REGION OF HEAT EXPANDS INTO THE MIDWEST/OHIO VALLEY THEN MID-
ATLANTIC/NORTHEAST NEXT WEEK AS THE UPPER-LEVEL RIDGING BUILDS IN.
HIGHS ARE FORECAST WELL INTO THE 90S, AND WITH LOWS IN THE UPPER
60S TO UPPER 70S PROVIDING LITTLE OVERNIGHT HEAT RELIEF. THIS HEAT
WAVE WILL LIKELY HAVE SOME STAYING POWER BEYOND THURSDAY.
SCHICHTEL/HAMRICK
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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