Prognostic Meteorological Discussion
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FXUS02 KWBC 221558
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 AM EDT FRI JUL 22 2016

VALID 12Z MON JUL 25 2016 - 12Z FRI JUL 29 2016

...OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT...

GUIDANCE FOR THIS MEDIUM RANGE PERIOD GENERALLY SHOWS LOW
AMPLITUDE MEAN FLOW ACROSS THE NORTHERN TIER WHICH EVOLVES INTO
MORE TROUGHING WITH AN AXIS NEAR THE MIDWEST BY FRIDAY/DAY 7. OUT
WEST...AN UPPER LEVEL RIDGE HOLDS STEADY ACROSS THE SOUTHWEST/FOUR
CORNERS REGION EVENTUALLY BUILDING INTO THE NORTHWEST BY THE END
OF THE WEEK. FOR THE MOST PART...MODELS ARE IN PRETTY DECENT
AGREEMENT WITH RESPECT TO THE LARGE SCALE SET-UP BUT THERE REMAINS
SOME UNCERTAINTY RESOLVING THE SMALLER SCALE DETAILS OF EMBEDDED
SHORTWAVES MOVING THROUGH CENTRAL AND EASTERN CANADA AND THE U.S.
NORTHERN TIER. THROUGH MID-WEEK...A BLEND OF THE 06Z GFS/00Z ECMWF
WITH THEIR RESPECTIVE MEANS WORKED WELL. BY THE END OF THE
WEEK...THE GFS CONTINUES TO SHOW A SLIGHT POSSIBLE OVER
DEVELOPMENT OF A SHORTWAVE TRACKING FROM THE NORTHERN PLAINS TO
THE UPPER MIDWEST. FOR THIS REASON...THE PROGS FOR DAYS 6/7 WERE
BASED MORE CLOSELY ON A MEAN COMPROMISE...WITH SLIGHTLY MORE
WEIGHT GIVEN TO THE ECMWF MEAN BECAUSE OF BETTER RUN TO RUN
CONTINUITY.


...WEATHER HIGHLIGHTS/THREATS...

A COLD FRONT CROSSING THE NORTHEAST/MID-ATLANTIC EARLY IN THE WEEK
AND EXTENDING BACK INTO THE PLAINS AS A STATIONARY FRONT WILL BE
ACCOMPANIED BY SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVIER
RAINFALL POSSIBLE. A SIGNAL FOR CONVECTION AND HEAVY RAINFALL
CONTINUES TO SHOW IN THE MODELS FROM THE NORTHERN PLAINS INTO THE
MID MISSISSIPPI VALLEY TUESDAY ONWARD DUE IN PART TO THIS FIRST
BOUNDARY EXITING THE REGION...BUT MOSTLY AS A SECOND BOUNDARY
DROPS IN ACCOMPANIED BY SHORTWAVE ENERGY ALOFT. AS DETAILS COME
INTO BETTER FOCUS...CONSULT THE SPC OUTLOOKS AS SOME OF THIS
ACTIVITY COULD BE STRONG TO SEVERE. ELSEWHERE...MAINLY
DIURNALLY/HEAT DRIVEN SHOWERS AND THUNDERSTORMS WILL CONTINUE
ACROSS THE SOUTHEAST/GULF COAST STATES WITH MONSOONAL MOISTURE AND
POSSIBLY MID-LEVEL MOISTURE FROM HURCN FRANK LOCATED WEST OF BAJA
FOR THE SOUTHWEST AND ROCKIES.

TEMPERATURES OVER THE NORTHEAST/MID-ATLANTIC SHOULD TREND
GRADUALLY LOWER WITH TIME BUT MAY STILL REMAIN ABOVE
NORMAL...ESPECIALLY AHEAD OF THE FRONT CROSSING MONDAY/TUESDAY
WITH NEAR RECORD VALUES POSSIBLE. AS THE RIDGE BUILDS OUT WEST BY
THE END OF THE WEEK...EXPECT TEMPERATURES TO TREND ABOVE NORMAL
WITH VALUES NEAR 10 DEGREES ABOVE NORMAL POSSIBLE ESPECIALLY FOR
COASTAL REGIONS AND INTO PARTS OF THE GREAT BASIN.


SANTORELLI

$$




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