240
FXUS02 KWBC 090658
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT MON JUN 9 2025
VALID 12Z THU JUN 12 2025 - 12Z MON JUN 16 2025
...HEAVY RAIN AND FLASH FLOOD THREAT FOR THE SOUTH-CENTRAL U.S.
THROUGH FRIDAY...
..OVERVIEW
A FRONT DRAPED WEST TO EAST NEXT WEEK ACROSS THE SOUTHERN TIER
WILL CONTINUE TO FOCUS HEAVY RAINFALL AND FLASH FLOODING THROUGH AT
LEAST FRIDAY, ESPECIALLY ACROSS PORTIONS OF TEXAS, OKLAHOMA, AND
INTO THE LOWER MISSISSIPPI VALLEY. NORTHERN STREAM ENERGY WILL
SUPPORT MODERATE TO HEAVY RAINFALL ACROSS THE NORTHERN ROCKIES TO
UPPER MIDWEST, WITH RAINFALL INCREASING IN COVERAGE BY NEXT WEEKEND
ACROSS THE OHIO VALLEY INTO THE EAST AHEAD OF NORTHERN AND
SOUTHERN STREAM ENERGY CONVERGENCE. TROUGHING OVER THE WEST COAST
WILL BE PERIODICALLY RENEWED BY SHORTWAVES ROUNDING THE BASE OF A
LARGER UPPER LOW, WITH ABOVE NORMAL TEMPERATURES EXPECTED TO
PREVAIL FOR INTERIOR PORTIONS OF THE WEST UNDERNEATH UPPER RIDGING.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW ABOVE AVERAGE AGREEMENT ON THE
OVERALL LARGE SCALE PATTERN AND EVOLUTION DURING THE MEDIUM RANGE
PERIOD, BUT THERE REMAINS CONSIDERABLE DIFFERENCES IN THE DETAILS
WHICH HAS DIRECT IMPLICATIONS ON SENSIBLE WEATHER. THE WPC FORECAST
FOR TONIGHT USED A MULTI-MODEL DETERMINISTIC BLEND FOR THE FIRST
HALF OF THE PERIOD, INCREASING TO MAJORITY ENSEMBLE MEANS BY DAYS 6
AND 7.
SOME DETAILS DIFFERENCES REMAIN WITH EVOLUTION AND PROGRESSION OF
A SHORTWAVE AS IT LIFTS OUT OF THE SOUTHERN PLAINS AND SORT OF
COMBINES OR INTERACTS WITH NORTHERN STREAM SHORTWAVE ENERGY FROM
THE GREAT LAKES. THIS, OF COURSE, HAS IMPLICATIONS FOR RAINFALL
AMOUNTS AND DISTRIBUTIONS ACROSS THE SOUTH-CENTRAL U.S. AND INTO
THE OHIO VALLEY AND THE NORTHEAST. THE BIGGEST SOURCE OF
UNCERTAINTY DURING THE PERIOD IS WITH TROUGHING OVER THE WEST COAST
AND REINFORCING PIECES OF ENERGY THAT ROUND THE BASE OF A SMALL
UPPER LOW MOVING DOWN THE WESTERN CANADIAN COAST. THE MODELS SHOW A
LOT OF RUN TO RUN VARIABILITY ON TIMING AND STRENGTH OF SHORTWAVES
INTO THE NORTHWEST AND THEN ESPECIALLY LATE IN THE PERIOD WITH
EVENTUAL PROGRESSION EASTWARD WITH THE TROUGH. ENSEMBLE MEANS
REMAIN MORE CONSISTENT AND OFFER A BETTER STARTING POINT BEFORE THE
DETAILS BECOME MORE IN FOCUS.
..WEATHER/HAZARDS HIGHLIGHTS
A FRONTAL BOUNDARY DRAPED GENERALLY WEST TO EAST ACROSS THE SOUTH
WILL CONTINUE TO PROVIDE FOCUS FOR NUMEROUS SHOWERS AND
THUNDERSTORMS THROUGH MOST OF THIS WEEK. GUIDANCE CONTINUES TO
CONVERGE ON TEXAS AND SURROUNDING STATES AS SEEING MULTIPLE ROUNDS
OF HEAVY RAIN, WITH PARTS OF THIS AREA (FROM NORTHERN TEXAS
NORTHWARD) ALREADY PRIMED FOR FLOODING WITH WET ANTECEDENT
CONDITIONS FROM RECENT RAINFALL. THUS A SLIGHT RISK REMAINS IN
PLACE ACROSS EAST-CENTRAL TEXAS INTO OKLAHOMA FOR THE DAY
4/THURSDAY EXCESSIVE RAINFALL OUTLOOK. AN EVENTUAL NEED FOR A
MODERATE RISK IN FUTURE UPDATES IS NOT OUT OF THE QUESTION, BUT
THERE REMAINS ENOUGH UNCERTAINTY TO PRECLUDE THAT NEED NOW AND IS
ALSO DEPENDENT ON SHORT RANGE RAINFALL OVER THE SAME AREA. SOME
SLIGHT EASTWARD SHIFT OF THE HEAVIEST RAINFALL AXIS ON DAY
5/FRIDAY, MORE INTO THE ARK-LA-TEX REGION. A SLIGHT RISK WAS
INTRODUCED FOR THE DAY 5 ERO TONIGHT.
A SHORTWAVE INTERACTING WITH A FRONTAL BOUNDARY ACROSS THE
NORTHERN TIER WILL BRING SHOWERS AND STORMS ACROSS PARTS OF THE
NORTHERN ROCKIES INTO THE UPPER MIDWEST. MOISTURE ANOMALIES SHOULD
BE ABOVE THE 90TH PERCENTILE IN MONTANA THROUGH THURSDAY, WHILE
CONVECTION RIDES ALONG THE CUSP OF THE INSTABILITY GRADIENT. THIS
SUPPORTS A MARGINAL RISK ON THE THURSDAY ERO, WHICH ALSO STRETCHES
EASTWARD INTO THE UPPER MIDWEST ALONG THE FRONT. A MARGINAL RISK
WAS INTRODUCED DAY 5 FOR PARTS OF THE UPPER GREAT LAKES REGION. BY
LATE WEEK AND NEXT WEEKEND, COMBINING UPPER LEVEL AND FRONTAL
FEATURES WILL ALLOW FOR RAINFALL SPREADING INTO THE EAST- CENTRAL
AND EASTERN U.S., WITH A GENERAL FOCUS AROUND THE MIDDLE
MISSISSIPPI/OHIO VALLEYS INTO THE NORTHERN MID- ATLANTIC, BUT WITH
AMPLE SPREAD IN THE DETAILS AT THIS POINT.
ABOVE NORMAL TEMPERATURES WILL CONTINUE ACROSS INTERIOR PARTS OF
THE WEST THROUGH MUCH OF THE PERIOD. DAYTIME HIGHS GENERALLY COULD
BE 10 TO 15 DEGREES ABOVE NORMAL AND MAY SPREAD GRADUALLY EASTWARD
WITH TIME. OTHERWISE, THE REST OF THE COUNTRY LOOKS NEAR NORMAL OR
WITHIN A FEW DEGREES OF NORMAL DEPENDING ON QUICK SYSTEMS MOVING
THROUGH.
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 (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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