020
FXUS01 KWBC 042058
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
458 PM EDT SAT JUL 04 2009
VALID 00Z SUN JUL 05 2009 - 12Z MON JUL 06 2009
THROUGHOUT THE SHORT RANGE PERIOD... THE UPPER LEVEL PATTERN WILL
FEATURE A LARGE TROUGH MOVING INTO THE NORTHWEST... FOLLOWED BY
RIDGING OVER THE ROCKIES AND BROAD TROUGHING OVER THE EASTERN HALF
OF THE CONUS.
AS ONE UPPER LEVEL IMPULSE EXITS THE NORTHEAST... A SURFACE LOW
AND ITS ASSOCIATED SHOWERS WILL EXIT NEW ENGLAND TONIGHT WITH THE
EXCEPTION OF NORTHERN MAINE AND SOUTHEASTERN CANADA. THE REST OF
THE REGION WILL STAY DRY UNTIL A COLD FRONT APPROACHES FROM THE
WEST ON MONDAY. THE PRESENCE OF UPPER LEVEL TROUGHING WILL
CONTINUE TO HOLD TEMPERATURES A BIT COOLER THAN USUAL.
A BROAD REGION OF RAIN WITH EMBEDDED THUNDERSTORMS OVER THE
MIDWEST THIS AFTERNOON IS EXPECTED TO CONTINUE PROPAGATING EAST
SOUTHEASTWARD INTO THE DAY ON SUNDAY. THIS AREA OF RAIN IS AHEAD
OF A SURFACE WARM FRONT WITH MOISTURE BEING TRANSPORTED
NORTHEASTWARD VIA MODERATE SOUTHWESTERLY FLOW IN THE LOW LEVELS OF
THE ATMOSPHERE. INSTABILITY AHEAD OF THE ASSOCIATED COLD FRONT
WILL LEAD TO AN INCREASE IN THUNDERSTORM COVERAGE THIS
AFTERNOON... WITH MODERATE TO LOCALLY HEAVY RAIN POSSIBLE AS THE
RAINFALL AXIS SHIFTS SOUTHEASTWARD WITH TIME. STEADY RAIN IS
EXPECTED TO REACH THE CENTRAL GULF COAST BY MONDAY MORNING...
WHILE THE ATTACHED SURFACE LOW BEGINS TO TRACK NORTHEASTWARD
THROUGH THE WESTERN ATLANTIC.
AS IS TYPICAL OF MID SUMMER... DIURNALLY DRIVEN THUNDERSTORMS WILL
DECREASE IN COVERAGE AND INTENSITY ACROSS THE ROCKIES TONIGHT
WHILE REGENERATING DURING THE AFTERNOON AND EVENING HOURS. ENOUGH
UPPER LEVEL SUPPORT IS IN PLACE TO SUPPORT A FEW OF THESE STORMS
BECOMING SEVERE... WITH LARGE HAIL AND DAMAGING STRAIGHT LINE
WINDS BEING THE MAIN THREATS. HIGHER AVAILABLE MOISTURE OVER THE
SOUTHERN STATES SHOULD SUPPORT HEAVIER RAINFALL TOTALS OVER
EASTERN COLORADO... NEW MEXICO AND WEST TEXAS COMPARED TO
PRECIPITATION OVER THE NORTHERN ROCKIES.
WITH THE APPROACH OF THE UPPER LEVEL TROUGH INTO THE NORTHWEST...
A COLD FRONT IS EXPECTED TO DEVELOP AND SLOWLY MOVE INTO THE
REGION TOMORROW. ALTHOUGH MOISTURE IS LIMITED ACROSS THE WEST...
UPSLOPE FLOW BEHIND THE COLD FRONT WILL LEAD TO OROGRAPHICALLY
DRIVEN RAIN ACROSS THE PACIFIC NORTHWEST BEGINNING SUNDAY NIGHT.
MUCH COOLER TEMPERATURES WILL BE NOTICED ACROSS THE NORTHWEST FOR
MONDAY AS THE PACIFIC AIR HAS A CHANCE TO MOVE IN.
OTTO
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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