Prognostic Meteorological Discussion
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000 FXUS01 KWBC 191940 PMDSPD SHORT RANGE FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 239 PM EST FRI DEC 19 2014 VALID 00Z SAT DEC 20 2014 - 00Z MON DEC 22 2014 ***HEAVY RAIN AND MOUNTAIN SNOW FOR THE NORTHWEST U.S.*** ***RAIN FOR THE GULF COAST REGION*** STRONG DEEP-LAYER FLOW FROM THE PACIFIC WILL DRIVE MOISTURE INTO THE NORTHWEST OVER THE NEXT SEVERAL DAYS. A STRONG UPPER JET COMBINED WITH A SERIES OF SHORTWAVES ROTATING THROUGH THE REGION PROVIDES A BROAD ENVIRONMENT OF STRONG ASCENT. THESE INGREDIENTS, COMBINED WITH A STRONG LOW LEVEL JET INTERCEPTING THE HIGHER TERRAIN WILL LEAD TO A PROLONG PERIOD OF MODERATE TO HEAVY RAINFALL ACROSS THE REGION AND SNOW IN THE HIGHER ELEVATIONS. RAINFALL OF SEVERAL INCHES WILL BE POSSIBLE WITH SNOWFALL OF OVER A FOOT. A COLD FRONT WILL MOVE INLAND BY TOMORROW EVENING AND PRECIPITATION WILL SPREAD INTO THE INTERMOUNTAIN WEST AND CENTRAL AND NORTHERN ROCKIES. ALONG THE GULF COAST, RAINFALL WILL CONTINUE TO MOVE SLOWLY EASTWARD WITH THE SURFACE LOW. A FRONTAL BOUNDARY EXTENDING EASTWARD FROM THE SURFACE LOW WILL BECOME STATIONARY AND SERVE AS A FOCUS FOR PRECIPITATION THROUGH THE PERIOD. WITH THE FRONTAL BOUNDARY DRAPED ALONG THE GULF COAST, CONVECTION INTO THE SOUTHEAST WILL BE ELEVATED IF AT ALL. LIGHT TO MODERATE RAINFALL CAN BE EXPECTED NORTH OF THE FRONT BUT SHOULD DIMINISH IN TIME WITH UPPER LEVEL FORCING WANING. KREKELER GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV $$

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