Big Storm for Central CONUS
Posted by JAC on 12/23/2009, 7:48 am
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
400 AM EST WED DEC 23 2009

VALID 12Z WED DEC 23 2009 - 00Z FRI DEC 25 2009

A BIG STORM IS ON TAP FOR THE CENTRAL U.S. BEGINNING TODAY AS A
LARGE CLOSED UPPER LEVEL LOW DIGS SOUTHEASTWARD FROM ARIZONA THIS
MORNING. WINTER STORM WATCHES...WARNINGS AND WINTER WEATHER
ADVISORIES ARE IN EFFECT FROM THE FOUR CORNERS REGION EASTWARD TO
THE TEXAS PANHANDLE AND AS FAR NORTH AS MONTANA AND MICHIGAN. A
COLD FRONT WILL MOVE INTO THE SOUTHERN PLAINS LATER TODAY WITH
SOUTHERLY FLOW AHEAD OF THE SYSTEM CONTINUING TO DRAW MOISTURE
NORTHWARD. IN ADDITION... A SECOND CLOSED UPPER LEVEL LOW OVER
ALBERTA WILL DIVE SOUTHWARD DURING THE DAY TODAY... DROPPING A
VERY COLD AIRMASS INTO THE NORTHERN AND CENTRAL PLAINS BY
THURSDAY. STRONG DYNAMICS ASSOCIATED WITH THESE TWO UPPER LOWS
WILL CONTRIBUTE TO A VARIETY OF WEATHER ACROSS THE U.S.

ABUNDANT LOW LEVEL MOISTURE WILL LEAD TO AN UNSTABLE AIRMASS FROM
THE ARKLATEX TO THE GULF COAST WITH SEVERE STORMS POSSIBLE AS THE
UPPER LOW APPROACHES TODAY. THE SEVERE THREAT WILL SPREAD EAST
OVERNIGHT AND INTO THURSDAY ALONG THE CENTRAL GULF COAST AS THE
COLD FRONT ADVANCES EASTWARD. ANOMALOUSLY HIGH MOISTURE WILL
CONTINUE NORTHWARD FROM THE GULF WHICH WILL PROVIDE FOR AN AXIS OF
HEAVY RAINFALL FROM THE CENTRAL GULF COAST UP THROUGH THE MIDDLE
MISSISSIPPI VALLEY. WIDESPREAD SNOW IS FORECAST FROM THE CENTRAL
AND NORTHERN HIGH PLAINS TO THE MISSISSIPPI RIVER THROUGH
THURSDAY... WITH THE GREATEST ACCUMULATIONS EXPECTED FROM EASTERN
NEBRASKA INTO THE UPPER MISSISSIPPI VALLEY WHERE ONE TO TWO FEET
COULD FALL BY CHRISTMAS MORNING. AS THE SURFACE LOW STRENGTHENS ON
THURSDAY... WINDS WILL INCREASE NEAR THE LOW WITH COLD NORTHERLY
FLOW THROUGHOUT THE PLAINS LIKELY LEADING TO BLOWING SNOW AND
REDUCED VISIBILITIES. SOUTHEASTERLY WINDS OVER THE MIDWEST WILL
ALSO IMPACT TRAVEL AS RAIN WILL CONTINUE TO FALL.

COLD AIR EAST OF THE APPALACHIANS WILL BE INITIALLY LOCKED IN AS
WARMER AIR ASSOCIATED WITH THIS SYSTEM BEGINS TO OVERRUN THE
REGION ON THURSDAY. FREEZING RAIN IS EXPECTED TO BE THE INITIAL
PRECIP TYPE ALONG THE NORTH CAROLINA AND VIRGINIA PIEDMONT BEFORE
CHANGING OVER TO RAIN.

SNOW OVER NORTHERN MAINE IS EXPECTED TO COME TO AN END TONIGHT AS
THE UPPER LEVEL LOW OVER THE NORTHEAST DEPARTS INTO THE ATLANTIC.
TEMPERATURES AHEAD OF THE LARGE CENTRAL U.S. UPPER LOW WILL WARM
ABOVE AVERAGE FROM THE GREAT LAKES TO THE NORTHEAST LATER THIS
WEEK.

OTTO











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Big Storm for Central CONUS - JAC, 12/23/2009, 7:48 am
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