Prognostic Meteorological Discussion
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FXUS02 KWBC 300538
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
138 AM EDT MON MAR 30 2015

VALID 12Z THU APR 02 2015 - 12Z MON APR 06 2015

...WARMEST TEMPERATURES OF THE YEAR LIKELY FOR THE NORTHEAST LATER
THIS WEEK...


...OVERVIEW...

MEDIUM RANGE PERIOD IS FORECAST TO TRANSITION TOWARD A DIFFERENT
PATTERN THAN SEEN IN THE PAST SEVERAL MONTHS WITH RIDGING CENTERED
OVER MEXICO. AN UPPER LOW CIRCLING AROUND HUDSON BAY WILL LOWER
HEIGHTS IN THE NORTHEAST NEXT WEEKEND. INITIAL TROUGHING IN THE
WEST WILL PUSH ACROSS THE CONUS AS A SFC COLD FRONT THU-SAT. BY
NEXT WEEKEND... AN UPPER LOW IS STILL FORECAST TO DROP SLOWLY
SOUTHEASTWARD OUT OF THE GULF OF ALASKA AND SETTLE INTO THE PAC NW
BY NEXT MON 4/6.

...GUIDANCE PREFERENCES...

TREND IN THE ENSEMBLE GUIDANCE OVER THE PAST FEW RUNS HAVE BEEN
TOWARD A MORE ECMWF/ECENS MEAN SOLUTION IN THE PAC NW -- THAT
IS... SLOWER WITH THE CLOSED UPPER LOW -- BUT A BIT MORE OF A
COMPROMISE SOLUTION IN THE EAST. SPREAD AMONG THE MEMBERS HAS
DECREASED TO NO WORSE THAN AVERAGE AND THE DETERMINISTIC MODELS
MOSTLY STAY WITHIN THEIR ENSEMBLE BOUNDS. GFS REMAINS QUICKER WITH
THE SFC FRONT THROUGH THE NORTHEAST/MID-ATLANTIC FRI COMPARED TO
THE OTHER GUIDANCE.... AND SLOWER IN THE SOUTHERN PLAINS AS IT
EMPHASIZES THE SOUTHERN STREAM OVER THE NORTHERN STREAM. BETTER
AGREEMENT/CONTINUITY LIES WITH THE ECMWF/UKMET AND ECENS MEAN
CLUSTER.

FOR THE WEEKEND INTO MONDAY... TRACK/EVOLUTION OF PAC NW UPPER LOW
IS DEPENDENT UPON UPSTREAM FLOW OVER ALASKA... WHICH SHOWS A LOT
OF ENSEMBLE SPREAD. RIDGING MAY GET SQUASHED OVER ALASKA DEPENDING
ON FURTHER UPSTREAM CLOSED LOW. GIVEN THE UNCERTAINTY... TRENDED
TOWARD A BLEND BETWEEN THE NAEFS AND ECENS MEAN AS THE GEFS
REMAINS JUST A BIT QUICKER.

...SENSIBLE WEATHER HIGHLIGHTS...

QUASI-ZONAL FLOW WILL SUPPORT CHANGEABLE TEMPERATURES... MODULATED
BY THE SFC COLD FRONT THU-SAT IN THE CENTRAL/EASTERN/SOUTHERN
STATES. OVERNIGHT MIN TEMPS WILL BE ON THE MILD SIDE IN ADVANCE OF
THE COLD FRONT -- ABOVE FREEZING THROUGH MOST OF NEW ENGLAND AFTER
A CHILLY START THURSDAY MORNING IN MAINE. 70S MAY ADVANCE PAST THE
MASON-DIXON LINE ON FRIDAY IN WHAT COULD BE THE WARMEST
TEMPERATURE IN OVER FOUR MONTHS FOR MUCH OF THE
MID-ATLANTIC/NORTHEAST. POST-FROPA TEMPS WILL RETURN TO BELOW AVG
READINGS BY ABOUT 5-15F. TEMPS IN THE PAC NW ARE FORECAST TO BE
BELOW AVG THANKS TO INCOMING TROUGHING... PUSHING THE ABOVE AVG
TEMPS TO ALONG/EAST OF THE DIVIDE INTO THE PLAINS.

PRECIPITATION SHOULD BE FAIRLY WIDESPREAD ALONG AND AHEAD OF THE
FRONT IN THE EAST LATER THIS WEEK... FOCUSED ESPECIALLY IN THE
OHIO VALLEY. ONCE HIGH PRESSURE MOVES IN BEHIND THE FRONT...
RETURN FLOW FROM THE GULF SHOULD HELP YIELD MORE RAIN IN TEXAS AND
THE LOWER MS VALLEY. BACK WEST... UPPER LOW AND ASSOCIATED SFC
FRONT WILL SPREAD RAIN AND MOUNTAIN SNOW FROM COASTAL WA/OR AND
NORCAL INLAND... BUT THIS DEPENDS ON HOW QUICKLY THE SYSTEM MOVES
EAST.


FRACASSO

$$





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