Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
000 FOUS11 KWBC 160857 QPFHSD PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 356 AM EST TUE JAN 16 2018 VALID 12Z TUE JAN 16 2018 - 12Z FRI JAN 19 2018 DAY 1-3... ***SOUTHERN TEXAS TO THE DEEP SOUTH*** STRONG COLD AIR ADVECTION BEHIND AN ARCTIC FRONT SETTLING SOUTHEASTWARD ACROSS THE GULF COAST AND THE DEEP SOUTH WILL CREATE AN ENVIRONMENT FAVORABLE FOR MAINLY LIGHT WINTRY PRECIPITATION. RIGHT ENTRANCE JET DYNAMICS ALOFT COUPLED WITH A POSITIVELY TILTED LONGWAVE TROUGH IN THE PRESENCE OF MODEST LEVELS OF MOISTURE WILL PROVIDE ENOUGH LIFT TO SUPPORT A BAND OF ONE TO LOCALLY TWO INCHES OF SNOW FROM EAST CENTRAL TEXAS TO CENTRAL/NORTHERN MISSISSIPPI, AND ALSO PARTS OF ALABAMA AND GEORGIA. ACCUMULATIONS WILL BE LIMITED BY THE RELATIVELY SHORT DURATION OF THE EVENT. A CONSIDERABLE PORTION OF THE ONGOING EVENT WILL HAVE OCCURRED BEFORE 12Z TUESDAY. FARTHER TO THE SOUTH ACROSS SOUTHERN TEXAS AND CLOSER TO THE CENTRAL GULF COAST, THE SUB-FREEZING LAYER WILL BE MORE SHALLOW WITH THE 850MB TEMPERATURES SLOWER TO COOL. THIS IS EXPECTED TO RESULT IN PERIODS OF LIGHT FREEZING RAIN AND SOME SLEET. AS THE BEST LIFT IS EXPECTED TO REMAIN PRIMARILY NORTH OF THIS AREA, ICE ACCUMULATIONS ARE EXPECTED TO REMAIN GENERALLY BELOW A TENTH OF AN INCH, ALTHOUGH LOCALIZED AMOUNTS EXCEEDING A TENTH OF AN INCH ARE POSSIBLE BY THE TIME THE EVENT IS OVER LATER TUESDAY. ***MID ATLANTIC REGION TO NEW ENGLAND*** RELATIVELY LIGHT WARM ADVECTION SNOW IS LIKELY BEGINNING TUESDAY MORNING ACROSS THE CENTRAL AND SOUTHERN APPALACHIANS AHEAD OF A SURFACE LOW TRACKING ACROSS THE GREAT LAKES REGION. THE POTENTIAL FOR MODERATE SNOW INCREASES BY TUESDAY NIGHT AS A NEW COASTAL LOW DEVELOPS OFF THE MID-ATLANTIC COAST. THE BEST AREA OF DYNAMIC FORCING IS EXPECTED FROM NORTHEAST PENNSYLVANIA TO EASTERN NEW ENGLAND THROUGH EARLY WEDNESDAY, WHERE THE BEST POTENTIAL FOR 4 TO 8 INCHES OF SNOW EXISTS. THE BEST LIFT IS REALIZED LATE TUESDAY NIGHT AND INTO WEDNESDAY MORNING ACROSS SOUTHEASTERN NEW ENGLAND, AND THIS IS WHEN THE SNOWFALL RATES SHOULD BE THE HEAVIEST. SNOW SHOULD COME TO AN END BY EARLY THURSDAY MORNING FOR EASTERN MAINE AS THE SURFACE LOW DEPARTS AND DRY AIR ADVECTION ENSUES. FARTHER TO THE SOUTH OVER PARTS OF VIRGINIA AND NORTH CAROLINA, MODELS CONTINUE TO INDICATE THE POTENTIAL FOR ANOTHER WEAK WAVE OF LOW PRESSURE TO DEVELOP NEAR THE OUTER BANKS BY WEDNESDAY MORNING WITH AN UPPER LEVEL JET STREAK ALOFT. ANOTHER ENHANCED AREA OF SNOWFALL AMOUNTS IS POSSIBLE FROM CENTRAL NORTH CAROLINA TO EASTERN VIRGINIA TO THE NORTHWEST OF THIS SURFACE WAVE, WHERE 1 TO 3 INCHES ARE POSSIBLE. ***WESTERN U.S.*** SNOW COVERAGE OVER THE NORTHWESTERN QUADRANT OF THE NATION IS EXPECTED TO INCREASE BY MIDWEEK AND ESPECIALLY INTO THURSDAY OWING TO STRONG HEIGHT FALLS ALOFT AND MULTIPLE PACIFIC SHORTWAVES APPROACHING THE COAST. THE FIRST SHORTWAVE SHOULD REACH THE NORTHWEST COAST EARLY TUESDAY, AND DECREASING SNOW LEVELS SHOULD SUPPORT LIGHT TO MODERATE SNOW OVER THE HIGHER ELEVATIONS OF THE WASHINGTON CASCADES AND THE HIGHEST MOUNTAINS OF NORTHERN OREGON. THE SECOND AND MUCH LARGER SHORTWAVE AND ASSOCIATED COLD FRONT BEGIN AFFECTING THE PACIFIC NORTHWEST ON WEDNESDAY, AND THEN IT WILL WORK ITS WAY INLAND ACROSS THE INTERMOUNTAIN WEST ON THURSDAY. THE WIDESPREAD ASCENT FROM THIS DEEP TROUGH AND COLD FRONT IS EXPECTED TO RESULT IN HEAVY SNOW FROM THE CASCADES TO THE SIERRA NEVADA, WITH SNOWFALL TOTALS APPROACHING A FOOT IN SOME CASES BY THURSDAY NIGHT. SIGNIFICANT SNOW ACCUMULATIONS IN EXCESS OF SIX INCHES ARE EXPECTED ACROSS THE HIGHER TERRAIN OF CENTRAL AND NORTHERN IDAHO, AND WESTERN MONTANA, WITH SNOW BEGINNING TO FALL OVER WESTERN WYOMING BY THE END OF THE FORECAST PERIOD THURSDAY NIGHT. THE PROBABILITY OF SIGNIFICANT ICING (0.25 INCH OR MORE) IS LESS THAN 10 PERCENT. D. HAMRICK $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.