445
FXUS02 KWBC 082018
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
417 PM EDT THU JUN 08 2023
VALID 12Z SUN JUN 11 2023 - 12Z THU JUN 15 2023
...A MULTI-DAY THUNDERSTORM AND LOCAL HEAVY RAIN THREAT WILL
CONTINUE INTO EARLY NEXT WEEK FROM A VERY SATURATED NORTHERN
ROCKIES THROUGH PORTIONS OF THE GREAT PLAINS...
...HEAVY RAIN/STRONG THUNDERSTORM THREAT FROM THE
MIDWEST/MID-SOUTH TO THE EAST THIS WEEKEND INTO EARLY NEXT WEEK
WITH CLOSED LOW GENESIS...
...TEXAS/LOWER MISSISSIPPI VALLEY EXCESSIVE HEAT THREAT NEXT WEEK
TO LINGER BEYOND DAY 7...
..OVERVIEW
THE ONGOING BLOCKY FLOW PATTERN LOOKS TO PERSIST INTO THE WEEKEND
WITH AN ANOMALOUSLY STRONG UPPER RIDGE/HIGH SANDWICHED BETWEEN
MEAN TROUGHING/CLOSED LOWS OVER THE SOUTHWEST AND THE NORTHEAST.
THIS PATTERN CONTINUES TO SUPPORT DIURNAL SHOWERS AND STORMS, SOME
LOCALLY HEAVY, FROM THE SOUTHERN PLAINS THROUGH THE NORTHERN
ROCKIES AND PARTS OF THE GREAT BASIN. THE NEXT WAVE ROUNDING THE
MID-CONTINENTAL RIDGE CROSSES ONTARIO TO WORK INTO THE GREAT
LAKES/NORTHEAST LATER THIS WEEKEND TO RE-ENERGIZE THAT PORTION OF
THE BLOCK WITH A LIKELY CLOSED OFF UPPER LOW TO LINGER AS IT
TRANSLATES SLOWLY EASTWARD ACROSS THE REGION EARLY NEXT WEEK. THIS
WOULD PROMPT AN ADDITIONAL AND LOCALLY ENHANCED PRECIPITATION
FOCUS INTO EARLY NEXT WEEK OUT ACROSS THE EAST-CENTRAL U.S. AS
AIDED BY SOUTHERN STREAM ENERGIES AND THEN UP THE EASTERN SEABOARD
ALONG WITH WRAPPING MOISTURE AROUND A DEEPENING SURFACE
LOW/FRONTAL SYSTEM. THE PATTERN SHOULD FINALLY BECOME MORE
PROGRESSIVE NEXT WEEK, WITH EXCESSIVE HEAT LIKLEY TO BUILD LOOKS
TO BUILD TO THE SOUTH ACROSS TEXAS AND INTO THE LOWER MISSISSIPPI
VALLEY THIS PERIOD.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THERE REMAINS GOOD AGREEMENT ON THE WEATHER PATTERN ACROSS THE
CONUS THE FIRST HALF OF THE PERIOD, BOLSTERING FORECAST
CONFIDENCE. A GENERAL MODEL BLEND WAS USED FOR SUNDAY-EARLY
TUESDAY. THERE'S ALSO GOOD SYNOPTIC AGREEMENT BEYOND TUESDAY THAT
THE PATTERN SHOULD FINALLY, BUT ONLY GRADUALLY, BREAK DOWN AND
BECOME MORE PROGRESSIVE. GREAT LAKES/MIDWEST TO NORTHEAST CLOSED
LOW TRANSLATION IS SHOWING BETTER AGREEMENT IN GUIDANCE. HOWEVER,
THE GFS AND TO A LESSER EXTENT THE GEFS REMAIN ON THE FASTER SIDE
OF THE FULL ENVELOPE OF GUIDANCE TO EJECT THE BULK OF ENERGY
ASSOCIATED WITH THE UPPER LOW OVER CALIFORNIA AND THE SOUTHWEST
OUT ACROSS THE ROCKIES/PLAINS AND EAST-CENTRAL STATES NEXT WEEK
WITHIN SOUTHERN STREAM FLOW. PREFER A BLEND CLOSER TO THE SLOWER
AND MORE AMPLIFIED ECMWF/CANADIAN AND ECMWF ENSEMBLES WHICH ALSO
FITS WELL WITH WPC CONTINUITY AND THE NATURE OF CLOSED
SYSTEMS/BLOCKY FLOW THAT TO TEND TO LINGER. LATEST 12 UTC CYCLE
GUIDANCE HAS OVERALL TRENDED A BIT SLOWER IN THIS SOUTHERN STREAM.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY RISK FOR HEAVY SHOWERS AND STRONG TO SEVERE THUNDERSTORMS
FROM THE SOUTHERN PLAINS THROUGH THE NORTHERN ROCKIES AND WESTWARD
INTO THE GREAT BASIN IS EXPECTED TO BE SLOW TO DISLODGE OVER ABOUT
THE NEXT WEEK AS TROPICAL PACIFIC MOISTURE REMAINS FUNNELED
NORTHWARD BETWEEN A STRONG CENTRAL U.S. RIDGE AND AN UPPER
LOW/TROUGH PARKED OVER CALIFORNIA/THE SOUTHWEST. A WEAKENING
BOUNDARY THROUGH THE REGION SHOULD ALSO HELP TO ENHANCE RAINFALL
TOTALS, WITH PARTICULAR CONCERNS OVER AREAS THAT HAVE BEEN VERY
WET AS OF LATE (NORTHERN AND CENTRAL ROCKIES/WESTERN GREAT
PLAINS). MAINTAINED A "SLIGHT RISK" ON THE DAY 4 EXCESSIVE
RAINFALL OUTLOOK IN EASTERN COLORADO AND FAR SOUTHEAST WYOMING
WITH A BROAD MARGINAL RISK ELSEWHERE DAY 4 AND ON DAY 5.
FARTHER INTO THE CENTRAL U.S. AND OHIO VALLEY, THE CLOSED LOW OVER
THE GREAT LAKES AND ASSOCIATED SURFACE COLD FRONT SHOULD HELP
FOCUS ANOMALOUS MOISTURE AND PLENTY OF INSTABILITY TO PRODUCE
LOCALLY HEAVY RAINFALL FROM THE UPPER GREAT LAKES/MIDWEST,
SOUTHWARD INTO THE TENNESSEE VALLEY AND PARTS OF THE SOUTHEAST ON
SUNDAY. AFTER COORDINATION WITH THE AFFECTED WFOS, AND CONSIDERING
LINGERING MODEL UNCERTAINTY AND ALSO HOW DRY THIS REGION HAS BEEN
LATELY, OPTED TO NOT DEPICT ANY SLIGHT RISK AREAS ON THE DAY 4 ERO
ACROSS PARTS OF THE TENNESSEE VALLEY DESPITE SOME GUIDANCE SIGNAL.
IT IS POSSIBLE A SLIGHT RISK WILL NEED TO BE REINTRODUCED IN
FUTURE UPDATES IF MODEL SUPPORT INCREASES. THE FRONT WILL PUSH
INTO THE EASTERN U.S. BY MONDAY WITH NUMEROUS SHOWERS AND STORMS
TO ACCOMPANY THE FRONT AS IT MOVES INTO THE EASTERN U.S..
ANTECEDENT DRY CONDITIONS AND THE PROGRESSIVE NATURE OF THE FRONT
PRECLUDE ANYTHING MORE THAN A BROAD MARGINAL RISK ON THE DAY 5 ERO
AT THIS TIME. ELSEWHERE, EJECTING ENERGIES OUT OF THE SOUTHWEST
ALSO LOOK TO FAVOR ADDITIONAL ROUNDS OF RAINFALL AND CONVECTION
AGAIN AROUND MID-WEEK NEXT WEEK FOR PARTS OF THE SOUTH-CENTRAL
PLAINS ONWARD TO THE EAST-CENTRAL STATES WITH FLOW/FRONTAL
PROGRESSION AND LEAD INTABILITY/MOISTURE FEED.
TEMPERATURES OVER THE NORTHERN TIER AND BACK INTO THE PACIFIC
NORTHWEST WILL CONTINUE TO BE WARM, WITH ANOMALIES 10-15 DEGREES
ABOVE NORMAL IN SOME PLACES, THROUGH ABOUT TUESDAY BEFORE THE
UPPER RIDGE FINALLY SUPPRESSES AND PUSHES EAST. UNDERNEATH
POSSIBLE CLOSED LOW DEVELOPMENT OVER THE GREAT LAKES/MIDWEST AND
BACK INTO THE SOUTHWEST/CALIFORNIA, TEMPERATURES SHOULD TREND
MODERATELY COOLER THAN NORMAL. THERE CONTINUES TO BE A SIGNAL FOR
A BUILDING EXCESSIVE HEAT THREAT FOR TEXAS INTO THE LOWER
MISSISSIPPI VALLEY AS UPPER RIDGING BECOMES BETTER ESTABLISHED
OVER THE REGION TO THE SOUTH OF A FRONTAL DRAPE. DAYTIME HIGHS
10-15F ABOVE NORMAL, WITH HEAT INDICES POSSIBLY IN EXCESS OF 110F,
MAINLY FOR CENTRAL TO LOWER TEXAS. SOME RECORD VALUES ARE
POSSIBLE. AS PER THE LATEST INFORMATION FROM THE CLIMATE
PREDICTION CENTER, THIS THREAT APPEARS LIKELY TO LINGER BEYOND DAY
7/THURSDAY.
SCHICHTEL/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
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS AND THE
GREAT LAKES, SUN-MON, JUN 11-JUN 12.
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE
TENNESSEE VALLEY, THE MIDDLE
MISSISSIPPI VALLEY, THE SOUTHERN APPALACHIANS, AND THE OHIO
VALLEY, SUN, JUN 11 AND WED-THU, JUN
14-JUN 15.
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL APPALACHIANS, THE
MID-ATLANTIC, AND THE GREAT LAKES
MON, JUN 12.
- FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHERN PLAINS.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN
ROCKIES AND THE NORTHERN GREAT
BASIN.
- EXCESSIVE HEAT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY
AND THE SOUTHERN PLAINS, TUE-THU,
JUN 13-JUN 15.
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page