222
FXUS02 KWBC 080651
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 AM EDT WED MAY 8 2024
VALID 12Z SAT MAY 11 2024 - 12Z WED MAY 15 2024
..EMERGING TEXAS/GULF COAST/SOUTHEAST HEAVY RAINFALL THREAT
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
OVERALL, GUIDANCE REASONABLY AGREES FOR MEAN TROUGHING TO LINGER
OVER THE EASTERN U.S. WHILE A MODEST REX BLOCK/SPLIT FLOW PATTERN
WILL TAKE ITS TIME TO DE-AMPLIFY OVER THE WESTERN U.S. THROUGH MUCH
OF A MAINLY BENIGN MEDIUM-RANGE WEATHER PATTERN THERE.
A NUMBER OF SHORTWAVE TROUGHS ARE FORECAST TO ROTATE AROUND THE
MEAN UPPER TROUGH IN THE EAST, AND THEY PRESENT SOME ISSUES AS TO
WHEN AND WHERE THE SHORTWAVES MAY INTERACT AND/OR AMPLIFY. THIS HAS
IMPLICATIONS TO COASTAL CYCLOGENESIS SPECIFICS FOR THIS WEEKEND.
WPC PROGS HAVE CONSISTENTLY SHOWN MODERATE LOW DEVELOPMENTS GIVEN
UNCERTAINTIES, BUT THERE HAVE BEEN SOME STRONGER ALL-THINGS COME
TOGETHER SOLUTIONS. MOST RECENTLY, THE 12 UTC UKMET OFFERED THE
MOST ROBUST LOW FAR SOUTHWARD OFFSHORE THE SOUTHEAST TO THEN
UP/OFF THE COAST, BUT THE 00 UTC UKMET HAS STARTED TO BACK-OFF.
AS FOR THE REX BLOCK IN THE WEST, MODELS GENERALLY SHOW A GRADUAL
PATTERN FLATTENING WITH TIME, WITH EMERGING DIFFERENCES ON WHETHER
A SOUTHERN STREAM LOW-AMPLITUDE TROUGH EJECTS TO THE SOUTHERN
PLAINS OR REMAINS SLOW-MOVING OVER THE SOUTHWEST INTO EARLY-MID
NEXT WEEK. DESPITE TIMING DIFFERENCES AND VARIED LEAD IMPULSES TO
CONSIDER, THERE IS A GROWING DOWNSTREAM RESPONSE SIGNAL FOR
RAINFALL FUELING MOISTURE/INSTABILITY TO INCREASINGLY RETURN/SPREAD
OVER TX AND THE GULF COAST REGION/SOUTHEAST SUNDAY-NEXT WEDNESDAY.
GIVEN UNCERTAINTIES, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY
DERIVED FROM A COMPOSITE BLEND OF COMPATIBLE GUIDANCE FROM THE
LATEST GEFS/ECMWF/CANADIAN ENSEMBLE MEANS AND THE NATIONAL BLEND
OF MODELS TO OFFER A SOLID PATTERN BASE AND REASONABLE CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
MODERATE RAINFALL WILL LINGER THIS WEEKEND OVER THE NORTHEAST WITH
WRAPBACK MOISTURE AND UPPER TROUGH SUPPORT AS DOWNSTREAM ENERGY
TRANSFERENCE LEADS TO COASTAL LOW GENESIS, BUT DETAILS REMAIN
UNCHARACTERISTICALLY UNCERTAIN EVEN AS WE ENTER SHORT RANGE TIME
FRAMES. UPSTREAM NORTHERN STREAM SYSTEMS WILL THEN PERIODICALLY
OFFER BOUTS OF MAINLY LIGHTER RAINS FROM THE NORTH-CENTRAL U.S. TO
THE GREAT LAKES/NORTHEAST THIS WEEKEND TO NEXT MIDWEEK, ALBEIT
ALSO WITH UNCERTAINTY IN FOCUS/TIMING, BUT WITH LIMITED IMPACT.
MEANWHILE TO THE SOUTH, A COOLING/SLOWING TRAILING FRONT ALONG
WITH A REINFORCING FRONT AND UPPER SHORTWAVES ARE EXPECTED TO
PERIODICALLY FOCUS PRECIPITATION FROM THE SOUTHERN ROCKIES/PLAINS
OUT THROUGH THE GULF OF MEXICO AND GULF COAST/FLORIDA THIS WEEKEND
THROUGH EARLY-MID NEXT WEEK. A GROWING BUT STILL NOT SOLIDIFIED
GUIDANCE SIGNAL OFFERS SUPPORT FOR MOISTURE TO INCREASE ALONG THE
GULF COAST AND VICINITY AHEAD OF THE RETURNING WARM FRONT. HEAVY
RAIN MAY WORK INLAND OVER TIME AS THE FRONT EDGES NORTHWARD. THE
WPC DAY 5/SUNDAY INTO MONDAY EXCESSIVE RAINFALL OUTLOOK INTRODUCED
A MARGINAL RISK AREA FROM SE TEXAS TO SOUTHERN LOUISIANA/MISSISSIPPI.
DRENCHED SOILS FROM RECENT HEAVY RAINS ALSO PROMPTED AN EMBEDDED
SLIGHT RISK AREA AROUND HOUSTON/SE TEXAS AND SW LOUISIANA. HEAVY
RAIN AND A THREAT OF RUNOFF ISSUES MAY ALSO SPREAD THROUGH THE
CENTRAL GULF COAST TO THE SOUTHEAST EARLY-MID NEXT WEEK TO MONITOR.
SCHICHTEL
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