Prognostic Meteorological Discussion
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FXUS01 KWBC 172039
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
438 PM EDT TUE OCT 17 2017

VALID 00Z WED OCT 18 2017 - 00Z FRI OCT 20 2017

...HEAVY RAIN POSSIBLE OVER PARTS OF THE PACIFIC NORTHWEST...

...HEAVY RAIN POSSIBLE OVER THE CENTRAL-NORTHEASTERN FLORIDA
COAST...

A FRONT EXTENDING FROM THE NORTHERN ROCKIES SOUTHWESTWARD INTO THE
PACIFIC NORTHWEST WILL MOVE EASTWARD TO THE GREAT LAKES/MIDDLE
MISSISSIPPI VALLEY INTO THE CENTRAL PLAINS BY THURSDAY.  MOISTURE
WILL BE LACKING WITH THE BOUNDARY SO THERE WILL BE A DRY FRONTAL
PASSAGE ALONG THE LENGTH OF THE FRONT FROM THE NORTHERN HIGH
PLAINS TO THE GREAT LAKES/CENTRAL PLAINS THROUGH THURSDAY.

IN THE MEANTIME BEHIND THE FRONT, ONSHORE FLOW WILL STREAM
MOISTURE INTO THE PACIFIC NORTHWEST ON STRONG LOW-LEVEL WIND
THROUGH THURSDAY MORNING WHEN THE STRONG LOW-LEVEL WIND DECREASES.
 THE FLOW WILL AID IN PRODUCING RAIN OVER PARTS OF THE PACIFIC
NORTHWEST INTO PARTS OF THE NORTHERN ROCKIES, ENDING OVERNIGHT
TUESDAY WHEN UPPER-LEVEL RIDGING MOVES OVER THE PACIFIC
NORTHWEST/NORTHERN ROCKIES.

MEANWHILE, A STRONGER FRONT OVER THE EASTERN PACIFIC MOVES CLOSE
TO THE NORTHWEST COAST BY THURSDAY MORNING.  A DEEP UPPER-LEVEL
TROUGH ASSOCIATED WITH THE BOUNDARY WILL BEGIN TO MOVE OVER THE
PACIFIC NORTHWEST ON WEDNESDAY AFTERNOON AND BECOMING STRONGER AS
THE FRONT APPROACHES.  THE APPROACHING UPPER-LEVEL TROUGH AND
ONSHORE FLOW WILL AID IN PRODUCING RAIN OVER PARTS OF THE
NORTHWEST COAST ON WEDNESDAY.  THE RAIN WILL BECOME HEAVY BY
WEDNESDAY EVENING OVER THE NORTHWEST AS THE RAIN MOVES FARTHER
INLAND INTO THE NORTHERN INTERMOUNTAIN REGION BY WEDNESDAY
EVENING.  OVERNIGHT WEDNESDAY, THE HEAVY RAIN WILL MOVE SOUTHWARD
ALONG THE PACIFIC NORTHWEST COAST APPROACHING NORTHERN CALIFORNIA
BY THURSDAY.  ADDITIONALLY, THE SNOW LEVELS WILL LOWER OVER THE
REGION WITH SNOW DEVELOPING OVER THE HIGHER ELEVATIONS OF THE
NORTHERN CASCADES OVERNIGHT WEDNESDAY INTO THURSDAY MORNING.

A PERSISTENT FRONT OVER SOUTHERN FLORIDA WILL REMAIN
QUASI-STATIONARY THROUGH THURSDAY.  IN ADDITION, UPPER-LEVEL
ENERGY OVER NORTHEASTERN FLORIDA WILL SLOWLY MOVE EASTWARD OUT
OVER THE ATLANTIC BY LATE WEDNESDAY NIGHT WHILE TROPICAL MOISTURE
OVER SOUTHERN FLORIDA SLOWLY RETREATS SOUTHWARD SOUTH OF THE
FLORIDA KEYS BY THURSDAY.  SHOWERS AND THUNDERSTORMS WILL DEVELOP
OVER SOUTHERN FLORIDA INTO NORTHEAST FLORIDA THAT WILL BEGIN TO
WANE EARLY THURSDAY MORNING OVER THE NORTHEAST COAST.  SHOWERS AND
THUNDERSTORMS WILL CONTINUE OVER THE SOUTHERN TIP OF FLORIDA
THROUGH THURSDAY MORNING.

FURTHERMORE, MOISTURE FROM THE PACIFIC WILL MOVE INLAND OVER
SOUTHERN CALIFORNIA INTO THE SOUTHWEST AS UPPER-LEVEL ENERGY MOVES
FROM THE PACIFIC TO THE SOUTHWEST BY THURSDAY.  LIGHT RAIN WILL
BEGIN OVER THE SOUTHWEST OVERNIGHT WEDNESDAY INTO THURSDAY.  THE
LIGHT RAIN WILL EXPAND INTO PARTS OF THE SOUTHERN ROCKIES BY
THURSDAY MORNING.


ZIEGENFELDER


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





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