Prognostic Meteorological Discussion
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000
FXUS01 KWBC 150559
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1258 AM EST FRI DEC 15 2017

VALID 12Z FRI DEC 15 2017 - 12Z SUN DEC 17 2017

...PATTERN CHANGE EXPECTED OVER THE WEEKEND...

THE WEATHER PATTERN OVER THE CONTINENTAL U.S. WILL INITIALLY BE
FEATURED WITH A BROAD EASTERN U.S. TROUGH AND A RIDGE CENTERED
NEAR THE WEST COAST.  AN UPPER LEVEL PATTERN CHANGE IS LIKELY BY
SUNDAY AS MULTIPLE DISTURBANCES ALOFT BREAK DOWN THE WESTERN U.S.
RIDGE AND MORE OF A ZONAL FLOW PATTERN RETURNS TO THE EASTERN
STATES.  A TROUGH IS EXPECTED TO AMPLIFY OVER THE ROCKY MOUNTAINS
DURING THE WEEKEND AND INCREASE THE CHANCE OF SNOW FOR THIS
REGION.  AFTER AN EXTENDED PERIOD OF DRY WEATHER, WIDESPREAD
ACCUMULATING SNOW IS LIKELY FOR THE CENTRAL AND ESPECIALLY THE
NORTHERN ROCKIES OVER THE NEXT FEW DAYS IN RESPONSE TO A
DEVELOPING SURFACE LOW OVER THE FOUR-CORNERS REGION AND SHORTWAVE
ENERGY ALOFT.  LAKE EFFECT SNOW IS ALSO EXPECTED DOWNWIND OF THE
GREAT LAKES AT TIMES.

WARM AND DRY CONDITIONS ARE EXPECTED FOR FLORIDA AND ESPECIALLY
THE LOWER ELEVATIONS OF THE DESERT SOUTHWEST AND INTO CENTRAL AND
SOUTHERN CALIFORNIA.  FIRE WEATHER CONCERNS WILL STILL EXIST
ACROSS PARTS OF CALIFORNIA OWING TO THE DRY CONDITIONS AND GUSTY
WINDS.  ON THE OTHER END OF THE TEMPERATURE SPECTRUM WILL BE
NORTHERN MINNESOTA AND NORTHERN NEW ENGLAND, WHERE READINGS WILL
REMAIN QUITE CHILLY WITH HIGHS IN THE TEENS AND 20S.
THUNDERSTORMS ARE NOT EXPECTED ACROSS THE CONTINENTAL U.S. UNTIL
SATURDAY, WHEN MOISTURE RETURNING NORTHWARD FROM THE GULF OF
MEXICO AHEAD OF A FRONT COULD FUEL THE DEVELOPMENT OF SOME
SCATTERED STORMS FOR SOUTHEAST TEXAS AND LOUISIANA.

D. HAMRICK


GRAPHICS AVAILABLE AT
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP
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