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000
FXUS01 KWBC 190854
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
453 AM EDT WED JUN 19 2013

VALID 12Z WED JUN 19 2013 - 12Z FRI JUN 21 2013

...AN ANOMALOUS UPPER CYCLONE WILL BRING UNSETTLED CONDITIONS TO
MUCH OF THE UPPER INTERMOUNTAIN WEST/NORTHERN ROCKIES...

...BELOW NORMAL TEMPERATURES SHOULD PREVAIL OVER MUCH OF THE
NORTHEASTERN STATES...


THE KEY FEATURE IMPACTING THE NATION THIS WEEK IS A DEEP UPPER
CYCLONE WHICH WILL SLOWLY MIGRATE TOWARD THE EAST DURING THE NEXT
COUPLE OF DAYS. THE COLD AIR ALOFT WILL INITIATE NUMEROUS SHOWERS
OVER THE NORTHWESTERN STATES WITH A BETTER FOCUS ALONG THE FRONTAL
ZONE. THE STRONGEST VERTICAL LIFT SHOULD GENERALLY STRADDLE THE
INTERNATIONAL BORDER WHICH WILL COINCIDE WITH WHERE THE HEAVIEST
RAINFALL IS EXPECTED. THROUGH THURSDAY MORNING, A THREAT FOR FLASH
FLOODING EXISTS OVER SECTIONS OF NORTHERN IDAHO AND INTO
NORTHWESTERN MONTANA. ADDITIONALLY, SOME OF THE STORMS MAY BECOME
SEVERE, PARTICULARLY NEAR THE MAIN SURFACE LOW WHICH IS WHERE THE
BETTER COMBINATION OF LIFT AND INSTABILITY WILL RESIDE. THE THREAT
FOR SEVERE WEATHER SHOULD GRADUALLY SHIFT EASTWARD IN RESPONSE TO
THE SLOW MOVING UPPER LOW WITH THE NORTHERN PLAINS/UPPER MIDWEST
GETTING IN ON THE ACTION BY THURSDAY. AN ADDITIONAL IMPACT FROM
THIS POWERFUL SYSTEM IS THE GUSTY WINDS IN RESPONSE TO THE
TIGHTENING PRESSURE GRADIENT. THE BREEZY CONDITIONS COMBINED WITH
A HOT AND DRY AIR MASS WILL ENHANCE THE WILDFIRE DANGER ACROSS
SECTIONS OF THE SOUTHWESTERN U.S. AND INTO THE FOUR CORNERS REGION.

LOOKING OUT EAST, A SURFACE BOUNDARY WILL HAVE NOSED AS FAR SOUTH
AS THE GULF COAST REGION WHICH WILL ALLOW A LARGE SURFACE HIGH TO
BUILD TO THE NORTH. THIS SHOULD PROVIDE TRANQUIL WEATHER TO MUCH
OF THE NORTHEASTERN TIER GIVEN THE STRONG SUBSIDING MOTION UNDER
THE INFLUENCE OF HIGH PRESSURE. ADEQUATE CONDITIONS FOR
RADIATIONAL COOLING WILL BE IN EFFECT OVERNIGHT WITH LOWS ABLE TO
DIP INTO THE 40S ACROSS THE GREAT LAKES AND INTO THE NORTHEASTERN
U.S. WITH THE FRONTAL ZONE ANCHORING THE GULF COAST, MUCH OF THE
THREAT FOR RAINFALL WILL EXIST OVER THE SOUTHEASTERN STATES THE
NEXT COUPLE OF DAYS. OF COURSE THE BETTER ACTIVITY WILL COINCIDE
WITH THE PEAK HEATING OF THE DAY WITH THUNDERSTORMS WEAKENING INTO
THE OVERNIGHT HOURS.


RUBIN-OSTER


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
$$