Prognostic Meteorological Discussion
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FXUS02 KWBC 210411
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1111 PM EST FRI JAN 20 2017

VALID 12Z TUE JAN 24 2017 - 12Z SAT JAN 28 2017

...SNOW POTENTIAL FOR THE INTERIOR NORTHEAST AND CENTRAL/HIGH
PLAINS TO THE UPPER MIDWEST EARLY NEXT WEEK...


OVERVIEW & GUIDANCE PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
UPPER RIDGING INITIALLY OVER SOUTHEASTERN CANADA WILL BRIDGE BACK
TOWARD WESTERN CANADA AS THE CONUS PATTERN TRANSITIONS TO A
RIDGE/TROUGH ORIENTATION. THE GFS/ECMWF ENSEMBLES REMAIN IN GOOD
AGREEMENT THROUGH THE PERIOD. EMBEDDED WITHIN THE FLOW WILL BE A
LEAD SYSTEM JUST OFF THE MID-ATLANTIC/NEW ENGLAND COAST ON TUESDAY
THAT WILL MOVE INTO THE CANADIAN MARITIMES AND A SECOND SURFACE
LOW LIFTING EAST-NORTHEASTWARD TOWARD THE GREAT LAKES ON
WEDNESDAY. THE ATTENDANT COLD FRONT IS FORECAST TO RACE OFF MOST
OF THE EAST COAST ON THURSDAY AND THROUGH THE SOUTHEAST/FLORIDA BY
FRIDAY. BY NEXT WEEKEND, BROAD CYCLONIC FLOW ACROSS THE EASTERN
HALF OF THE CONUS MEANS A COOLER/DRIER PATTERN WHILE THE WEST IS
STUCK UNDER UPPER RIDGING. THOUGH THE GFS/GEFS WOBBLED A BIT TO
THE WEST WITH THE LEAD LOW IN THE EAST, A GENERAL MODEL/ENSEMBLE
BLEND (INCLUDING THE ECMWF AND CANADIAN) SUFFICED THROUGH THE
PERIOD. DIFFERENCES IN THE GUIDANCE LIED OVER THE SOUTHEAST WITH
THE PROGRESSION OF THE COLD FRONT LATER IN THE WEEK AND THEN IN
THE PACIFIC NORTHWEST WITH HOW MUCH THE UPPER RIDGING CAN KEEP ANY
PACIFIC SYSTEM OFFSHORE. A MIDDLE GROUND SOLUTION SEEMS REASONABLE
GIVEN THE ENSEMBLE SPREAD IN EACH AREA.


WEATHER HIGHLIGHTS/THREATS
~~~~~~~~~~~~~~~~~~~~~~~~~~
THE LEAD SYSTEM IN THE EAST/NORTHEAST WILL LIKELY TRANSPORT
SIGNIFICANT MOISTURE FROM THE TROPICS/SUBTROPICS NORTHWARD THEN
NORTHWESTWARD INTO RELATIVELY MILD AIR FOR THIS TIME OF THE YEAR
FOR AN ARRAY OF WINTRY PRECIPITATION TYPES. SNOW WILL LIKELY BE
LIMITED TO THE INTERIOR HIGHER ELEVATIONS. THE UPSTREAM PLAINS
KICKER SYSTEM WILL ENSURE THIS ONE WILL NOT LINGER BUT
PRECIPITATION RATES COULD BE IMPRESSIVE. FARTHER WEST IN THE
PLAINS, SNOW WILL EXPAND TO THE NORTHEAST ON THE NORTH SIDE OF THE
LOW WHERE SIGNIFICANT ACCUMULATIONS ARE POSSIBLE ALONG/NEAR THE
I-90/US-20 CORRIDORS FROM NE/SD TO SOUTHERN WI.

BY LATER IN THE WEEK, THE PATTERN WILL BECOME RATHER QUIET AS THE
FRONT SHOULD SETTLE SOUTH OF FLORIDA AND HIGH PRESSURE WILL BE IN
FIRM CONTROL OF THE WEST, SEIZING INCREASING TERRITORY TO THE EAST
WITH TIME. DESPITE THE HIGHER 500 HPA HEIGHTS, NORTHERLY UPPER
FLOW AND 700MB TEMPS ABOUT 1-2 SIGMAS BELOW AVERAGE WILL KEEP
TEMPERATURES BELOW AVERAGE. MILD TEMPERATURES IN THE EAST SHOULD
TREND BACK TOWARD CLIMATOLOGY AS TROUGHING INCREASES ACROSS THE
AREA AND UPPER LEVEL TEMPERATURES SLOWLY DECREASE. LAKE EFFECT
SNOW PRODUCTION WILL PICK UP THURSDAY/FRIDAY WITH
NORTH/NORTH-NORTHWEST FLOW.


FRACASSO

$$





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