821
FXUS02 KWBC 051900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT FRI JUL 5 2024
VALID 12Z MON JUL 08 2024 - 12Z FRI JUL 12 2024
..BERYL LIKELY TO AFFECT TEXAS EARLY NEXT WEEK
..DANGEROUS HEAT WAVE IN THE WEST PERSISTS INTO NEXT WEEK
..OVERVIEW
THE MOST PROMINENT LARGE SCALE FEATURES DURING THE PERIOD WILL BE A
PERSISTENT UPPER RIDGE OVER THE WEST SUPPORTING A DANGEROUS AND
LIKELY RECORD-SETTING HEAT WAVE ACROSS MUCH OF THE REGION INTO NEXT
WEEK, AND A POSITIVELY TILTED PLAINS/MISSISSIPPI VALLEY/GREAT LAKES MEAN
TROUGH WHOSE SOUTHERN PERIPHERY MAY INTERACT WITH TROPICAL STORM
BERYL (FORECAST BY THE NATIONAL HURRICANE CENTER TO STRENGTHEN BACK
TO HURRICANE STATUS AS IT TRACKS INTO THE WESTERN GULF OF MEXICO
THIS WEEKEND). BERYL SHOULD BRING A PERIOD OF WINDY CONDITIONS AND
HEAVY RAINFALL TO PARTS OF TEXAS, WITH POTENTIAL FOR NORTHEASTWARD
PROGRESSION OF RAINFALL NEXT WEEK. FOR NOW THE UNCERTAINTY IN HOW
BERYL INTERACTS WITH THE MEAN TROUGH ALOFT IS LEADING TO LOWER THAN
DESIRED CONFIDENCE REGARDING IMPORTANT DETAILS OF THE FORECAST.
MEANWHILE, HOT AND HUMID CONDITIONS WILL LIKELY CONTINUE FOR MUCH
OF THE SOUTHERN STATES AND EXTENDING TO THE EAST COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE IS SHOWING SOME SIGNIFICANT TRENDS FOR BERYL, WITH
A NORTHWARD ADJUSTMENT AS THE SYSTEM REACHES THE WESTERN GULF
COAST AND THEN GREATER POTENTIAL FOR NORTHEASTWARD RECURVATURE
THEREAFTER. UPON REACHING EASTERN TEXAS, THE DEGREE OF INTERACTION
WITH THE MEAN TROUGH ALOFT (AND SHORTWAVE DETAILS WITHIN THE
TROUGH) WOULD AFFECT THE TRACK AND TIMING OF BERYL'S SURFACE
REFLECTION. THE PAST COUPLE ICON RUNS HAVE BEEN VERY PROGRESSIVE
WHILE CMC RUNS STILL SEEM TO BE CATCHING UP FROM BEING ON THE FAR
LEFT SIDE OF THE ENVELOPE. 00Z MACHINE LEARNING (ML) MODELS
GENERALLY FAVORED THE RECURVATURE SCENARIO, BETWEEN THE SLOWER 00Z
ECMWF AND FASTER 00Z/06Z GFS (12Z UKMET LEANING SOMEWHAT FASTER AS
WELL). EASTWARD AND THEN MUCH FASTER TREND OF THE NEW 12Z ECMWF
HIGHLIGHTS THE FORECAST UNCERTAINTY. THE UPDATED MANUAL FORECAST
REFLECTS THIS TREND IN PRINCIPLE WHILE STAYING SOMEWHAT
CONSERVATIVE WITH DETERMINISTIC QPF GIVEN THE LOWER THAN AVERAGE
CONFIDENCE FOR THE TIME BEING. CONSULT NATIONAL HURRICANE CENTER
PRODUCTS FOR THE LATEST INFORMATION REGARDING BERYL.
AS FOR OTHER ASPECTS OF THE FORECAST, THERE IS MODERATE SPREAD
AMONG THE DYNAMICAL/ML GUIDANCE FOR A TROUGH WITH EMBEDDED LOW
TRACKING FROM THE NORTHEASTERN PACIFIC INTO WESTERN CANADA MID-LATE
WEEK WITH NO DOMINANT CLUSTERING FOR THE TIME BEING. THIS FEATURE
MAY HELP TO PUSH A FRONTAL SYSTEM INTO THE FAR NORTHWESTERN U.S. BY
LATE NEXT WEEK. A BLENDED/INTERMEDIATE SOLUTION LOOKS LIKE A GOOD
STARTING POINT HERE. MEANWHILE SOME DIFFERENCES ARISE FOR UPPER
TROUGH DETAILS FROM EASTERN CANADA INTO THE CENTRAL U.S. BY LATE
NEXT WEEK. SOME GFS RUNS AND THE NEW 12Z ECMWF SHOW WEAKER
TROUGHING OVER THE PLAINS/MISSISSIPPI VALLEY BY NEXT FRIDAY VERSUS
MOST OTHER GUIDANCE, WHILE GUIDANCE IS SPLIT OVER THE DEPTH OF
TROUGHING OVER SOUTHEASTERN CANADA BY THEN. THE LATTER ISSUE WILL
AFFECT A SURFACE FRONT LIKELY TO BE NEAR THE EAST COAST LATE NEXT
WEEK. THERE IS ALSO SOME INDICATION THAT STRONG ATLANTIC UPPER
RIDGING MAY BUILD WESTWARD SOMEWHAT AND SERVE TO STALL THE EAST
COAST FRONT.
WITH ADJUSTMENTS TO ACCOUNT FOR THE OFFICIAL TRACK OF BERYL, THE
UPDATED FORECAST STARTED WITH AN OPERATIONAL MODEL COMPOSITE EARLY
IN THE PERIOD (MORE ECMWF/GFS EMPHASIS RELATIVE TO THE UKMET/CMC)
AND THEN TRANSITIONED TOWARD HALF GEFS/ECENS INPUT BY THE END OF
THE PERIOD NEXT FRIDAY.
..WEATHER/HAZARDS HIGHLIGHTS
ONGOING MODEL TRENDS FOR BERYL TEMPER CONFIDENCE IN EXACT DETAILS
OF MAGNITUDE AND AXIS OF HEAVIEST RAINFALL, WITH SENSITIVITY TO
BOTH TRACK AND SPEED. CURRENT CONSENSUS WOULD SUGGEST AT LEAST
SEVERAL INCHES OF RAINFALL IN SOUTH/EAST TEXAS DURING THE FIRST
HALF OF NEXT WEEK WITH POTENTIAL FOR SOUTHWESTERLY FLOW ALOFT TO
SPREAD SOME DEGREE OF ENHANCED RAINFALL NORTHEASTWARD FROM TEXAS
AFTER MIDWEEK. THE DAYS 4-5 EXCESSIVE RAINFALL OUTLOOKS FOR MONDAY
AND TUESDAY REFLECT SLIGHT RISK AREAS WHERE THE RELATIVELY HIGHER
POTENTIAL FOR HEAVY RAINFALL EXISTS. REFLECTING LATEST MODEL
TRENDS, THE DAY 4 SLIGHT RISK EXTENDS A LITTLE FARTHER
NORTHEASTWARD VERSUS CONTINUITY WHILE THE DAY 5 SLIGHT RISK
REFLECTS A MORE PRONOUNCED NORTHEASTWARD EXTENT. MONDAY'S SLIGHT
RISK CONTINUES TO BE A HIGHER-END SLIGHT BEFORE INCREASING
DIVERGENCE IN GUIDANCE FOR BERYL'S TRACK AND ESPECIALLY TIMING. A
NEARBY FRONT WILL ALSO PROVIDE A FOCUS FOR POTENTIALLY SIGNIFICANT
CONVECTION/HEAVY RAINFALL. THERE IS CERTAINLY POTENTIAL FOR
UPGRADES TO MODERATE RISKS IN FUTURE UPDATES IF PLACEMENT OF HIGHER
TOTALS COMES INTO BETTER AGREEMENT. THIS FRONT AND MOISTURE COULD
LINGER INTO AND BEYOND MIDWEEK, BUT WITH STEADILY DECREASING
CONFIDENCE IN THE SPECIFICS.
SCATTERED THUNDERSTORMS ARE LIKELY ACROSS THE GULF COAST STATES
THROUGH MUCH OF NEXT WEEK GIVEN A MOIST AND UNSTABLE AIRMASS IN
PLACE. ALSO, EARLY IN THE WEEK PARTS OF THE SOUTHEAST WILL LIKELY
SEE LINGERING ANOMALOUS MOISTURE WITH SUFFICIENT INSTABILITY TO
SUPPORT SOME LOCALIZED CONVECTION WITH HIGH RAINFALL RATES--
SUPPORTING ADDITION OF A MARGINAL RISK AREA ON DAY 4 GIVEN SOME
CARRYOVER OF THE PATTERN FROM THE DAY 3 TIME FRAME. FARTHER NORTH,
THE UPPER TROUGH PUSHING ONE OR MORE COLD FRONTS THROUGH THE
NORTH-CENTRAL TO NORTHEASTERN U.S. ALSO WILL LEAD TO SOME STORMS,
WITH THE BULK OF THE ACTIVITY MOVING EAST WITH TIME FROM THE
MIDWEST/GREAT LAKES MONDAY TOWARD THE EASTERN U.S. TUESDAY-
THURSDAY. SOME FOCUS OF THE CONVECTIVE RAIN AND SUFFICIENT
INSTABILITY FOR HEAVY RAIN RATES IN MUCH OF NEW YORK AND
PENNSYLVANIA HAVE PROMPTED A MARGINAL RISK IN THE ERO FOR DAY
5/TUESDAY. MEANWHILE, BY TUESDAY AND BEYOND, SOME MOISTURE MAY FEED
INTO THE FOUR CORNERS STATES IN A MONSOONAL PATTERN, AND HAVE A
MARGINAL RISK IN PLACE FOR DAY 5/TUESDAY MAINLY FOR NEW MEXICO,
ESPECIALLY CONSIDERING SENSITIVITIES DUE TO BURN SCARS AND AREAS
THAT HAVE SEEN AMPLE RAINFALL RECENTLY.
THE WEST WILL CONTINUE TO SEE A MAJOR TO EXTREME AND LONG-LIVED
HEAT WAVE INTO NEXT WEEK. HIGHS EXCEEDING 110F SHOULD BE WIDESPREAD
IN THE DESERT SOUTHWEST, WITH TYPICALLY HOTTER LOCATIONS EXCEEDING
120F. FARTHER NORTH, HIGHS INTO THE 100S ARE FORECAST INTO OREGON
AND WASHINGTON AND EAST INTO THE INTERMOUNTAIN WEST, AS
TEMPERATURES SOAR 10-20F ABOVE NORMAL WITH LOCALLY HIGHER
ANOMALIES. NUMEROUS DAILY RECORDS ARE LIKELY TO BE BROKEN DURING
THIS HEAT WAVE, WITH MONTHLY RECORDS NOT OUT OF THE QUESTION. THE
PROLONGED NATURE OF THE HEAT WAVE AND RECORD WARM OVERNIGHT
TEMPERATURES WILL INCREASE HEAT STRESS. MEANWHILE, WARMER THAN
AVERAGE TEMPERATURES IN THE NORTHEAST EARLY IN THE WEEK SHOULD
MODERATE BY MIDWEEK. THE SOUTHEAST SHOULD SEE NEAR NORMAL HEAT FOR
THIS TIME OF YEAR--WHICH IS STILL HOT AND HUMID. THE SOUTH-CENTRAL
U.S. SHOULD SEE SOME MINOR HEAT RELIEF WITH BELOW AVERAGE
TEMPERATURES GIVEN THE CLOUDS AND RAIN CHANCES.
RAUSCH/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
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page