Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXUS02 KWBC 241542
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1141 AM EDT MON JUL 24 2017

VALID 12Z THU JUL 27 2017 - 12Z MON JUL 31 2017

...PATTERN OVERVIEW...

LONGWAVE PATTERN FOR THE LAST WEEK OF JULY WILL RESUME THE UPPER
RIDGE PARKED OVER THE FOUR CORNERS REGION WITH A SLIGHT
RETROGRESSION INTO THE GREAT BASIN BY NEXT WEEK. THIS WILL FAVOR
TROUGHING TO ITS EAST, SETTLING INTO THE GREAT LAKES AND NORTHEAST
STATES THU-SAT AND THEN INTO THE SOUTHEAST BY SUN/MON. THIS WILL
TAKE A SURFACE FRONT EASTWARD OUT OF THE OHIO VALLEY, OFF THE
MID-ATLANTIC COAST, BUT SLOWLY DROPPING SOUTHWARD THROUGH THE
TENNESSEE VALLEY FRI/SAT AND TOWARD THE GULF COAST BY NEXT WEEK. A
REINFORCING SHOT OF COOLER AIR FROM CANADA MAY BREACH THE
US/CANADIAN BORDER NEXT SUN/MON IN THE UPPER MIDWEST AND UPPER
LAKES REGION.


...GUIDANCE EVALUATION/PREFERENCES...

THE ENSEMBLES REMAIN IN GOOD AGREEMENT WITH THE LARGE SCALE
PATTERN ACROSS THE CONUS. THE DETERMINISTIC COUNTERPARTS ALSO FELL
IN LINE AND A BLEND OF THE RECENT GFS/GEFS AND ECMWF/ECENS MEAN
OFFERED A GOOD STARTING POINT WITH ONLY MINOR CHANGED FROM
CONTINUITY. DIFFERENCES BECOME MORE NOTICEABLE BY NEXT SUN/MON IN
THE EAST WHERE THE GFS HAS BEEN MORE AGGRESSIVE WITH THE UPPER
TROUGH THAN THE ECMWF, SUGGESTING A CLOSED LOW SPLICING OFF OVER
THE SOUTHEAST NEXT WEEK. WHILE THE CONSENSUS IS FOR AT LEAST
BONAFIDE TROUGHING, DISMISSED THE GFS AT THIS POINT GIVEN ITS MORE
POTENT SOLUTION. IN ADDITION, THE FORECAST BEYOND SATURDAY IN THE
TROPICAL EASTERN PACIFIC IS QUITE UNCERTAIN AS HURRICANE HILARY
AND TROPICAL STORM IRWIN POTENTIALLY INTERACT IN THE SOUTHWEST
CORNER OF THE CONUS MAP. AGAIN, DISMISSED THE 00Z/06Z GFS RUNS
THAT BRING HILARY NORTHWARD ALONG 120W NEARING 30N (ABOUT 230
MILES SW OF SAN DIEGO) AS THE ENSEMBLE CONSENSUS LIES FARTHER
WEST. THE 17Z NHC/WPC TROPICAL COORDINATION CALL WILL REFINE THE
POSITION FOR NEXT SUN/MON.


FRACASSO


...WEATHER HIGHLIGHTS...

WHILE THE HOT SPOT IN THE FORECAST SHOULD BE ACROSS THE DESERT
SOUTHWEST WITH AFTERNOON HIGHS EXCEEDING 110 DEGREES...THE MOST
ANOMALOUS WARMTH WILL BE ACROSS THE PACIFIC NORTHWEST INTO THE
UPPER INTERMOUNTAIN WEST/NORTHERN ROCKIES. EXPECTED HIGHS SHOULD
BE AT LEAST 10 DEGREES ABOVE AVERAGE AS HIGHS SOAR WELL INTO THE
90S OVER INLAND LOCATIONS WHILE READINGS CLOSER TO THE 80S ARE
LIKELY ALONG AND WEST OF I-5. ACROSS THE EASTERN U.S...SOME AREAS
WILL BE AT OR SLIGHTLY BELOW CLIMATOLOGY GIVEN THE PRESENCE OF THE
UPPER TROUGH AND ASSOCIATED RAINFALL CHANCES.

GIVEN THE PRESENCE OF THE UPPER RIDGE ACROSS THE FOUR CORNERS
REGION...AMPLE MONSOONAL MOISTURE WILL CONTINUE TO CHURN ITS WAY
NORTHWARD INTO THE DESERT SOUTHWEST. ADDITIONALLY...ANY MOISTURE
EMERGING FROM DECAYING TROPICAL CYCLONES IN THE EASTERN PACIFIC
WILL NEED TO BE ACCOUNTED FOR AS WELL. AREAS OF THE FOUR CORNERS
REGION SHOULD BE QUITE WET WITH CONVECTION GRADUALLY SLIDING
EASTWARD THROUGH THE HIGHER TERRAIN AND EVENTUALLY INTO THE
ADJACENT GREAT PLAINS. LOOKING TO THE EASTERN HALF OF THE
NATION...IT SHOULD REMAIN UNSETTLED ALONG THE FRONTAL ZONE WHICH
MAY BE SLOW MOVING AT TIMES GIVEN THE LINGERING UPPER TROUGH.


RUBIN-OSTER



$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.