176  
FXUS01 KWBC 220803  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 AM EST THU FEB 22 2018  
 
VALID 12Z THU FEB 22 2018 - 12Z SAT FEB 24 2018  
 
...COLD AND UNSETTLED WEATHER IS EXPECTED OVER THE WEST INCLUDING  
SOME HEAVY SNOW OVER THE ROCKIES...  
 
...ADDITIONAL HEAVY RAINFALL AND WIDESPREAD CONCERNS FOR FLOODING  
WILL PERSIST ACROSS PARTS OF THE SOUTHERN PLAINS, LOWER  
MISSISSIPPI VALLEY AND THE OHIO VALLEY...  
 
...WARM TEMPERATURES ARE GENERALLY EXPECTED TO CONTINUE ACROSS A  
LARGE PORTION OF THE EAST...  
 
MUCH OF THE WEST WILL REMAIN IN A COLD, ACTIVE WET PATTERN THROUGH  
THE END OF THE WEEK THANKS TO A SERIES OF IMPULSES THAT WILL DROP  
SOUTH AND REINFORCE THE BROAD UPPER LEVEL TROUGH OF LOW PRESSURE.  
SNOW WILL SPREAD ACROSS THE PACIFIC NORTHWEST, GREAT BASIN AND TO  
THE ROCKIES. SNOW WILL BE HEAVY AT TIMES ACROSS THE HIGHER TERRAIN  
IN NORTHERN CALIFORNIA, SOUTHERN IDAHO, NEVADA, UTAH AND FOR  
PORTIONS OF THE CENTRAL ROCKIES. THE COLD AIRMASS IN PLACE OVER  
THE REGION WILL KEEP AFTERNOON HIGHS GENERALLY 10 TO 20 DEGREES  
COOLER THAN USUAL FOR LATE FEBRUARY.  
 
THE WAVES OF ENERGY WILL EXIT THE FRONT RANGE AND TRACK ACROSS THE  
PLAINS WHERE A QUASI-STATIONARY FRONTAL BOUNDARY EXTENDS FROM THE  
LOWER MISSISSIPPI VALLEY TO THE OHIO/TENNESSEE VALLEY AND  
MID-ATLANTIC. MULTIPLE ROUNDS OF HEAVY RAIN IS FORECAST AS WARM  
GULF MOISTURE ADVECTS NORTHWARD ALONG THE BOUNDARY. THIS RAINFALL  
IS EXPECTED TO OCCUR OVER A BROAD AREA ALREADY SATURATED FROM  
PRIOR DAYS OF EXCESSIVE RAIN. A SLIGHT TO MODERATE RISK FOR FLASH  
FLOODING MAIN STEM RIVER FLOODING WILL PERSIST THROUGH THE END OF  
THE WEEK. IN THE COLD SECTOR, SCATTERED TO WIDESPREAD SNOW WILL BE  
POSSIBLE FOR PORTIONS OF THE PLAINS, MIDWEST AND UPPER MISSISSIPPI  
VALLEY - NUMEROUS WINTER WEATHER ADVISORIES ARE IN EFFECT FOR  
THESE AREAS.  
 
MUCH OF THE EAST COAST LIES WITHIN THE WARM SECTOR OF THIS SYSTEM  
AND WILL CONTINUE TO HAVE TEMPERATURES TOPPING OFF IN THE 70S AND  
80S, WHEREAS, THE CENTRAL CONUS WILL BE BELOW FREEZING AS MUCH AS  
10 TO 20 DEGREES BELOW NORMAL.  
 
REGARDING THE THREAT OF WINTER WEATHER, THERE WILL BE THE APPROACH  
OF A WAVE OF LOW PRESSURE FROM THE TENNESSEE VALLEY ON THURSDAY  
THAT WILL ACTUALLY INTERACT WITH SUFFICIENT COLD AIR OVER PARTS OF  
THE UPPER OHIO VALLEY, FAR NORTHERN MID-ATLANTIC AND INTERIOR OF  
THE NORTHEAST FOR A STRIPE OF SOME ACCUMULATING SNOW AND ICE.  
MEANWHILE, THERE WILL ALSO BE A SWATH OF ACCUMULATING SNOW AND ICE  
ACROSS PORTIONS OF ESPECIALLY THE CENTRAL PLAINS, MIDWEST AND  
GREAT LAKES FOR THURSDAY AND FRIDAY AS LOW PRESSURE RIDES  
NORTHEAST UP ACROSS THE REGION.  
 
CAMPBELL/ORRISON  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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