527
FXUS01 KWBC 280834
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
431 AM EDT WED OCT 28 2009
VALID 12Z WED OCT 28 2009 - 00Z FRI OCT 30 2009
WHILE MOST AREAS EAST OF THE MISSISSIPPI RIVER SHOULD CLEAR OUT BY
LATE WEDNESDAY NIGHT...THE SAME WILL NOT HOLD TRUE FROM THE PLAINS
WESTWARD. A STRONG UPPER TROUGH HAS DESCENDED ALL THE WAY INTO THE
DESERT SOUTHWEST BRINGING A SIGNIFICANT WINTER STORM TO MUCH OF
THE ROCKY MOUNTAINS. MODERATE TO HEAVY SNOW WILL CONTINUE ACROSS
THE CENTRAL ROCKIES AND UP INTO THE LARAMIES IN SOUTHEASTERN
WYOMING THROUGHOUT THE DAY ON WEDNESDAY. EVENTUALLY THE WINTRY
PRECIPITATION WILL SPREAD NORTHEASTWARD INTO NEBRASKA AND UP INTO
THE NORTHERN PLAINS. AS A PIECE OF ENERGY SPLITS OFF FROM THE
UPPER LOW OVER THE FOUR CORNERS REGION...THE FRONTAL SYSTEM WILL
BEGIN TO PUSH THROUGH THE CENTRAL PLAINS BY EARLY THURSDAY
MORNING. A COMMA-HEAD OF MODERATE TO HEAVY SNOWFALL IS EXPECTED TO
WRAP AROUND THE BACKSIDE OF THE SURFACE LOW CENTER WHICH WILL BE
ACCOMPANIED BY FAIRLY GUSTY WINDS. THIS IS FORECAST TO DROP
SIGNIFICANT AMOUNTS OF SNOW ACROSS THE DAKOTAS. THE COMBINATION OF
THE EXPECTATIONS OF HEAVY SNOWFALL WITH THE VAST WIND FIELD MAY
CREATE CONDITIONS HAZARDOUS FOR TRAVEL ACROSS THE REGION. BY
FRIDAY MORNING...THE WEATHER SYSTEM WILL HAVE REACHED THE
MISSISSIPPI VALLEY AND WILL THEREBY PUT AN END TO MUCH OF THE
PRECIPITATION ACROSS THE ROCKIES AND PLAINS. IN THE WAKE...EXPECT
THERE TO BE A DECENT SNOW COVER OVER THE REGION...ESPECIALLY
ACROSS THE HIGHER ELEVATIONS WHICH WILL GREATLY BENEFIT THE LOCAL
SKI RESORTS.
THE OTHER ASPECT OF THIS DYNAMIC SYSTEM IS THE HEAVY RAINFALL
ACROSS THE SOUTHERN AND CENTRAL PLAINS. IN ADVANCE OF THIS FRONTAL
BOUNDARY...A RICH PLUME OF GULF MOISTURE WILL INTERACT WITH THE
APPROACHING COLD AIR MASS TO HELP PRODUCE MODERATE TO HEAVY
SHOWERS AND THUNDERSTORMS. SOME OF THESE STORMS MAY TAKE ON A
SEVERE NATURE WITH THE BIGGEST THREAT ACROSS THE SOUTHERN PLAINS
THROUGH THURSDAY MORNING...AND SPREADING INTO THE LOWER
MISSISSIPPI VALLEY BY THE FOLLOWING DAY. IN ADDITION TO THE SEVERE
POTENTIAL...HEAVY RAINFALL WHICH MAY INCLUDE LOCALIZED FLASH
FLOODING IS ALSO A DISTINCT POSSIBILITY. RAINFALL AMOUNTS ACROSS
THE LOWER MISSISSIPPI VALLEY AND UP INTO THE OZARKS MAY PRODUCE
FLOODING ON THURSDAY AS DEPICTED BY THE HPC EXCESSIVE RAINFALL
FORECAST.
ELSEWHERE...AN UPPER TROUGH SWINGING NORTHEASTWARD THROUGH THE
TENNESSEE RIVER VALLEY IS HELPING PRODUCE WIDESPREAD RAIN SHOWERS
OVER MUCH OF THE OHIO VALLEY AND MID-ATLANTIC REGION. THE HIGHLY
PROGRESSIVE DISTURBANCE IS EXPECTED TO PUSH OFFSHORE BY LATE
WEDNESDAY WHICH WILL BRING AN END TO THE RAINFALL BY WEDNESDAY
NIGHT. A SURFACE RIDGE WILL THEN DOMINATE THE REMAINDER OF THE
WORK WEEK ACROSS THE EAST COAST WHICH WILL BRING TRANQUIL
CONDITIONS TO THE MUCH OF THE EASTERN THIRD OF THE NATION.
RUBIN-OSTER
GRAPHIC AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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