Prognostic Meteorological Discussion
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FXUS02 KWBC 061601
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 PM EDT FRI MAY 06 2016

VALID 12Z MON MAY 09 2016 - 12Z FRI MAY 13 2016

...PATTERN OVERVIEW...
THE OMEGA BLOCK IN THE U.S. IS EXPECTED TO GRADUALLY DEAMPLIFY AS
THE LARGE-SCALE LOWS ON BOTH THE WEST AND THE EAST COASTS SLOWLY
RETREAT.  THE WESTERN U.S. RETREATING LOW WILL APPEAR TO MOVE
ACROSS THE PLAINS THROUGH DAY 4/TUESDAY BEFORE SHEARING OFF TO THE
EAST ALONG A QUASI-STATIONARY FRONT ACROSS THE MID-ATLANTIC
THROUGH DAY 7/NEXT FRIDAY.  MEANWHILE...SHORTWAVE ENERGY WILL DIG
DOWN FROM WESTERN CANADA INTO THE NORTHERN ROCKIES AND NORTHERN
PLAINS THROUGH DAY 5/WEDNESDAY BEFORE INTERACTING WITH OR TRYING
TO MERGE WITH THE SHEARED-OFF ENERGY ACROSS THE EASTERN U.S.

...MODEL PREFERENCES/UNCERTAINTY ASSESSMENT...
MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THE AFOREMENTIONED
PATTERN EVOLUTION.  THE UNCERTAINTY IS REGARDING THE DEGREE OF
INTERACTION BETWEEN THE SHORTWAVE DIGGING DOWN FROM WESTERN CANADA
WITH THE REMAINING ENERGY COMING FROM THE WESTERN U.S. RETREATING
LOW.  BOTH OF THE ECMWF AND THE GFS ARE STILL COMING TO A STEADY
SOLUTION ON THE DETAILS OF THE PATTERN FROM DAY 5/WED AND BEYOND.
THUS...AN ENSEMBLE MEAN APPROACH WILL BE INCORPORATED FOR THIS
TIME FRAME.  BETWEEN THE GEFS AND THE EC MEANS...IT APPEARS THAT
THE EC MEANS CONTINUE TO PROVIDE STEADIER SOLUTIONS THAN THOSE
FROM THE GEFS.  THE WPC BLEND USES A BLEND OF THE 00Z ECMWF AND
06Z GFS STARTING ON DAY 3...AND TRENDS MORE TOWARDS THE EC MEANS
BY DAY 7.  THE TWO PIECES OF ENERGY COULD MERGE INTO A SINGLE
SYSTEM BY DAY 7 IN THE NORTHEASTERN U.S.

...WEATHER HIGHLIGHTS...
THE DAY 3-4 SYSTEM EXITING THE SOUTH CENTRAL PLAINS IS EXPECTED TO
GENERATE DEEP CONVECTION...WITH STEEP MID-LEVEL LAPSE
RATES...PRODUCING SCATTERED TO NUMEROUS SHOWERS AND BELOW NORMAL
TEMPERATURES BENEATH THE COLD CORE MID-LEVEL CYCLONE. A
WEST-TO-EAST ORIENTATION OF THE PRECIPITATION AXIS (DOWNSTREAM) IS
ANTICIPATED FOR DAY 4...BETWEEN THE CENTRAL PLAINS AND THE OHIO
VALLEY...BEFORE THE CYCLONE EXITS THE EAST COAST ALONG A
QUASI-STATIONARY FRONTAL BOUNDARY ACROSS THE MID-ATLANTIC.

ACROSS THE WEST...SPLIT-FLOW GENERATES A PERIOD OF OFFSHORE FLOW
AND MILD...TRANQUIL CONDITIONS ALONG THE COASTLINE...AND ABOVE
NORMAL TEMPERATURES AND GENERALLY DRY WEATHER...FOR THE INTERIOR
(WEST OF THE DIVIDE).

KONG/VOJTESAK

$$





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