Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 250559
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 AM EDT THU MAY 25 2017

VALID 12Z SUN MAY 28 2017 - 12Z THU JUN 01 2017

PATTERN OVERVIEW AND MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE MODEL GUIDANCE IS VERY AGREEABLE IN SHOWING A DEEP CYCLONE
LIFTING FROM THE GREAT LAKES INTO CANADA.  IN ITS WAKE, PACIFIC
SYSTEMS INVADE THE SOUTHWEST EARLY IN THE WEEK AND MOVE INTO THE
PACIFIC NORTHWEST NEXT WEDNESDAY OR THURSDAY.  DUE TO THE
AGREEMENT, THE PRESSURES, 500 HPA HEIGHTS, AND WIND GRIDS USED AN
EVEN BLEND OF THE 18Z GFS, 12Z ECMWF, 12Z UKMET, AND 12Z CANADIAN
FOR THE PATTERN FROM SUNDAY INTO TUESDAY MORNING.  AFTER THAT,
USED INCREASING AMOUNTS OF THE 12Z NAEFS/ECMWF ENSEMBLE MEAN
SOLUTIONS.  THE DEW POINT, CLOUD, WEATHER, PRECIPITATION CHANCE,
AND TEMPERATURE GRIDS WERE AN EVEN SPLIT OF THE ENSEMBLE MEAN
GUIDANCE AND THE DETERMINISTIC 12Z CANADIAN/12Z ECMWF/18Z GFS
SOLUTIONS.  THE DAYS 4-7 QPF RESEMBLE A ROUGH COMPROMISE OF THE
00Z GFS AND 12Z ECMWF SOLUTIONS.


WEATHER HIGHLIGHTS
~~~~~~~~~~~~~~~~~~
WARM AND DRY CONDITIONS ARE EXPECTED ACROSS MUCH OF THE WESTERN
THIRD OF THE NATION THIS WEEKEND AND INTO EARLY NEXT WEEK, WITH
THE GREATEST POSITIVE TEMPERATURE ANOMALIES EXPECTED OVER THE
PACIFIC NORTHWEST WHERE DAYTIME TEMPERATURES COULD SURPASS 90F IN
SOME LOCATIONS.  MEANWHILE, AN UPPER TROUGH/CLOSED LOW PROGRESSING
THROUGH THE NORTH-CENTRAL U.S. WILL SPREAD BELOW NORMAL
TEMPERATURES FROM THE NORTHERN/CENTRAL PLAINS THIS WEEKEND TO MUCH
OF THE MIDWEST/GREAT LAKES REGION EARLY NEXT WEEK.

MOISTURE ADVECTING NORTHWARD OUT OF THE GULF OF MEXICO WILL FUEL
POTENTIALLY HEAVY RAIN AND THUNDERSTORMS ALONG/AHEAD OF A FRONTAL
BOUNDARY PRESSING EAST/SOUTHEASTWARD OUT OF THE SOUTHERN PLAINS
INTO THE MID-SOUTH, WITH LESSER AMOUNTS ACROSS THE
NORTHEAST/MID-ATLANTIC STATES.  THE TAIL END OF THE BOUNDARY IS
EXPECTED TO STALL AND INTERACT WITH ENERGY MOVING THROUGH THE
SOUTHWEST, BRINGING ADDITIONAL HEAVY RAINFALL TO PORTIONS OF THE
SOUTHERN PLAINS.

ROTH/GERHARDT
$$




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