Prognostic Meteorological Discussion
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000
FXUS01 KWBC 222010
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
409 PM EDT MON MAY 22 2017

VALID 00Z TUE MAY 23 2017 - 00Z THU MAY 25 2017

...UNSETTLED WEATHER EXPECTED TO MOVE INTO MUCH OF THE EASTERN AND
NORTHWESTERN U.S. FOR THE NEXT COUPLE OF DAYS...

AN ACTIVE WEATHER PATTERN IS TAKING SHAPE ACROSS THE U.S. OVER THE
NEXT COUPLE OF DAYS AS THE UPPER-LEVEL FLOW BECOMES INCREASINGLY
AMPLIFIED.  FIRST OF ALL, A COOL AIR MASS BEHIND AN OCCLUDED
CYCLONE CENTERED NORTH OF THE GREAT LAKES WILL PIVOT AROUND THE
CYCLONE CENTER AND SURGE SOUTHWARD THROUGH THE PLAINS THROUGH
WEDNESDAY.  THIS WILL BRING ANOTHER BATCH OF UNSEASONABLY COOL AIR
DOWN THE MID-SECTION OF THE COUNTRY.  DAYTIME SURFACE HEATING
UNDER UPPER-LEVEL COLD AIR WILL PROMOTE SCATTERED AFTERNOON
SHOWERS OVER THE CENTRAL PLAINS TODAY, MOVING INTO MUCH OF THE
MIDWEST AND INTO THE UPPER GREAT LAKES ON TUESDAY BEHIND THE
SURFACE COLD FRONT.  AHEAD OF THE FRONT, SCATTERED THUNDERSTORMS
CAN BE EXPECTED OVER THE SOUTHERN PLAINS.  AREAS OVER WESTERN TO
SOUTHERN TEXAS COULD SEE SEVERE THUNDERSTORMS TODAY INTO TOMORROW.
 AS THE COOL AIR MASS CONTINUES TO ADVANCE TO THE SOUTHEAST, IT
WILL BEGIN TO INTERACT WITH ANOTHER FRONTAL BOUNDARY ALREADY IN
PLACE FROM NEAR THE GULF COAST EXTENDING INTO THE EAST COAST.  THE
RESULT WILL BE THE FORMATION OF A NEW LOW PRESSURE SYSTEM WEST OF
THE APPALACHIANS FROM TUESDAY NIGHT INTO WEDNESDAY.  SHOWERS AND
THUNDERSTORM WILL THEN EDGE FURTHER EASTWARD INTO MUCH OF THE OHIO
VALLEY, DOWN INTO THE SOUTHEASTERN U.S. AND THE GULF COAST ON
WEDNESDAY AS SUNSHINE RETURNS THROUGH THE PLAINS STATES WITH COOL
TEMPERATURES.  THE CENTRAL ROCKIES WILL ONCE AGAIN SEE THE ARRIVAL
OF SNOW OVER THE HIGHER ELEVATIONS TONIGHT.

MEANWHILE, A RATHER COMPACT AND DEEP UPPER-LEVEL LOW IS FORECAST
TO DIP SOUTHEASTWARD FROM BRITISH COLUMBIA INTO THE NORTHWESTERN
U.S. DURING THE NEXT FEW DAYS.  THIS WILL TRIGGER THE FORMATION OF
A RATHER STRONG LOW PRESSURE SYSTEM TO BE CENTERED OVER ALBERTA
WEDNESDAY MORNING.  A SURGE OF COOL AIR WILL ARRIVE BEHIND A
STRONG COLD FRONT, REPLACING THE RECENT SPELL OF MILD WEATHER OVER
THE PACIFIC NORTHWEST.  THE HIGHEST ELEVATIONS OF THE NORTHERN
CASCADES AND NORTHERN ROCKIES COULD EVEN SEE SNOW MOVING IN ON
WEDNESDAY.  THE FRONT WILL CONTINUE TO PUSH RAPIDLY TO THE SOUTH
AND EAST, TRIGGERING SHOWERS AND THUNDERSTORMS DURING THE DAY ON
WEDNESDAY FROM THE SIERRAS EASTWARD ACROSS THE GREAT BASIN,
NORTHERN UTAH, WYOMING, MONTANA AND THE NEARBY HIGH PLAINS.

KONG


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

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