939
FXUS02 KWBC 070648
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 AM EDT FRI JUL 07 2023
VALID 12Z MON JUL 10 2023 - 12Z FRI JUL 14 2023
...HEAT EXPECTED TO REBUILD FROM THE SOUTHWEST TO THE CENTRAL GULF
COAST INTO NEXT WEEK...
...HEAVY RAIN CONCERNS LIKELY TO FOCUS OVER PORTIONS OF THE GULF
COAST AND THE NORTHEAST ON MONDAY, AND BACK INTO THE MIDWEST BY
MID-WEEK...
..OVERVIEW
MOST OF THE GUIDANCE IN THE MEDIUM RANGE PERIOD CONTINUES TO SHOW
THE LARGE SCALE FLOW SETTLING INTO A FAIRLY PERSISTENT PATTERN
THROUGH NEXT WEEK. A DEEP UPPER LOW ANCHORED NEAR HUDSON BAY LOOKS
TO SEND WAVES OF ENERGY ACROSS THE MIDWEST INTO THE NORTHEAST TO
PROVIDE A FOCUS FOR MULTIPLE EPISODES OF SHOWERS AND THUNDERSTORMS
WITH SOME AREAS OF HEAVY RAINFALL POSSIBLE. MEANWHILE, AN UPPER
LEVEL RIDGE WILL EXPAND HAZARDOUS HEAT FROM THE SOUTHWEST U.S.
INTO THE SOUTHERN PLAINS AND THE CENTRAL GULF COAST REGION, LIKELY
PERSISTING INTO THE WEEK TWO TIME FRAME PER THE LATEST FORECASTS
FROM THE CLIMATE PREDICTION CENTER.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODELS SHOW VERY GOOD AGREEMENT ON THE OVERALL LARGE SCALE PATTERN
ACROSS THE CONUS THROUGH NEXT WEEK. AS IS TYPICAL FOR THESE TIME
FRAMES, THERE REMAINS PLENTY OF UNCERTAINTIES IN THE DETAILS
REGARDING A COUPLE OF SHORTWAVES MOVING THROUGH MEAN TROUGHING
FROM THE MIDWEST INTO THE NORTHEAST, WHICH HAS IMPLICATIONS FOR
SURFACE FEATURES AND SENSIBLE WEATHER. THIS IS RELATED TO RATHER
SIGNIFICANT UNCERTAINTIES IN THE PLACEMENT OF THE PARENT UPPER LOW
NEAR HUDSON BAY LATER NEXT WEEK. THE GFS (INCLUDING THE NEW 00Z
RUN) IS NOTABLY THE FARTHEST NORTH, ALTHOUGH THE LATEST 00Z CMC IS
THE GREATEST OUTLIER BRINGING THE UPPER LOW WELL TO THE SOUTH AND
EAST OF THE CONSENSUS. THE ENSEMBLE MEANS SEEM TO SUPPORT A
SOLUTION FARTHER NORTH, CLOSEST TO THAT OF THE GFS AND ECMWF. THE
WPC FORECAST FOR TONIGHT BLENDED THE DETERMINISTIC SOLUTIONS FOR
THE FIRST HALF OF THE PERIOD, TRENDING TOWARDS THE ENSEMBLE MEANS
WITH THE GFS/ECMWF FOR THE LATTER HALF OF THE WEEK.
..WEATHER/HAZARDS HIGHLIGHTS
A SURFACE FRONT DRAPED ACROSS THE SOUTHERN U.S. SHOULD HELP FOCUS
AREAS OF HEAVY RAINFALL EARLY IN THE WEEK, PARTICULARLY NEAR THE
CENTRAL GULF COAST, WHERE A SLIGHT RISK IS HIGHLIGHTED ON THE DAY
4/MONDAY EXCESSIVE RAINFALL OUTLOOK ALONG WITH A MARGINAL RISK ON
DAY 5/TUESDAY. GUIDANCE CONTINUES TO TREND SOUTH WITH THE HEAVIEST
RAINFALL AND THIS IS REFLECTED IN THIS LATEST UPDATE. THERE ARE
ALSO SIGNALS FOR A POSSIBLE BAND OF CONFECTION EXTENDING BACK
NORTHWEST INTO THE CENTRAL PLAINS WITHIN AN AXIS OF FAVORABLE
MOISTURE AND INSTABILITY AND TO THE NORTH OF THE WESTERN EDGE OF
THE FRONT WHICH SHOULD LIFT BACK NORTH AS A WARM FRONT. MAINTAINED
THE MARGINAL RISK FOR THIS REGION ON DAY 4 AS THERE IS STILL A
FAIR BIT OF UNCERTAINTY IN THE SPECIFICS OF WHERE THE BEST HEAVY
RAINFALL WILL SET UP. A WEAK SURFACE LOW LIFTING ALONG THE
NORTHEAST COAST SHOULD FOCUS RAINFALL TO THE NORTH OF IT ACROSS
NORTHERN NEW ENGLAND/MAINE AND A MARGINAL RISK WAS MAINTAINED ON
MONDAY'S OUTLOOK AND CONTINUED INTO THE TUESDAY AS WELL.
ELSEWHERE, A COLD FRONT SAGGING SOUTH ACROSS THE NORTHERN
U.S./MIDWEST SHOULD ALSO FOCUS SHOWERS AND STORMS TUESDAY AND
BEYOND. THE NEW DAY 5/TUESDAY EXCESSIVE RAINFALL OUTLOOK
HIGHLIGHTS A MARGINAL RISK ALONG THIS BOUNDARY, WITH POTENTIAL FOR
AN UPGRADE TO A SLIGHT EVENTUALLY ESPECIALLY IF HEAVY RAIN FALLS
WITHIN A REGION FROM SOUTHEAST NEBRASKA INTO ILLINOIS WHICH HAS
SEEN ABOVE NORMAL PRECIPITATION AS OF LATE. ENOUGH UNCERTAINTY
STILL TO PRECLUDE THAT INCLUSION FOR NOW.
HAZARDOUS HEAT IS EXPECTED TO RETURN AND EXPAND ACROSS THE
SOUTHERN TIER THROUGH AT LEAST NEXT WEEK (AND LIKELY EXTENDING
BEYOND PER LATEST CPC FORECASTS) AS THE UPPER RIDGE STRENGTHENS
AND DRIFTS SLIGHTLY TO THE WEST. THE GREATEST HIGH TEMPERATURE
ANOMALIES (OF 10-15F ABOVE AVERAGE) SHOULD BE NEAR THE UPPER HIGH
CENTER OF WESTERN TEXAS AND INTO NEW MEXICO, WITH A BROADENING
AREA OF ABOVE NORMAL TEMPERATURES ELSEWHERE. THE OPPRESSIVE
HUMIDITY LEADING TO MAXIMUM HEAT INDICES REACHING 110F OR GREATER
ACROSS SOUTHERN/EASTERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY
WITH LITTLE RELIEF OVERNIGHT WILL RESULT IN ANOTHER PERIOD OF
HAZARDOUS TO EXCESSIVE HEAT ACROSS THIS REGION, WITH SOME RECORDS
FOR DAYTIME HIGHS AND WARM OVERNIGHT LOWS POSSIBLE AS WELL.
HUMIDITY WILL BE NATURALLY LOWER BACK INTO THE SOUTHWEST, THOUGH
AIR TEMPERATURES COULD STILL REACH 110-115F IN SOME PLACES. ABOVE
NORMAL TEMPERATURES WILL ALSO EXPAND INTO THE WEST COAST STATES AS
WELL LATER NEXT WEEK. ELSEWHERE, A COLD FRONT DROPPING SOUTH FROM
CANADA SHOULD BRING TEMPERATURES DOWN TO 5-10F BELOW AVERAGE OVER
THE NORTHERN TO CENTRAL PLAINS NEXT WEDNESDAY-FRIDAY. THE
SOUTHEAST AND UP THE EAST COAST MAY SEE SLIGHTLY COOLER THAN
AVERAGE TEMPERATURES ON MONDAY, MODERATING BACK TO NEAR NORMAL
TUESDAY AND BEYOND.
SANTORELLI
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, 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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