Prognostic Meteorological Discussion
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FXUS02 KWBC 201336
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 AM EST FRI JAN 20 2017

VALID 12Z MON JAN 23 2017 - 12Z FRI JAN 27 2017

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


SYNOPTIC PATTERN & MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RETROGRADING RIDGING ACROSS CANADA FORCED BY A TROUGH SHARPENING
ALONG 160W LONGITUDE SHOULD REORIENT THE TROUGH, STRETCHING FROM
EASTERN CANADA THROUGH THE CENTRAL/SOUTHERN PLAINS TOWARDS THE SEA
OF CORTEZ/GULF OF CALIFORNIA.  THE GUIDANCE REMAINS IN BETTER THAN
AVERAGE AGREEMENT.  FOR THE PRESSURES, 500 HPA HEIGHTS, AND WIND
GRIDS, A COMPROMISE OF THE 00Z CANADIAN/00Z ECMWF/00Z UKMET/06Z
GFS WAS UTILIZED EARLY BEFORE USING INCREASING AMOUNTS OF THE 00Z
ECMWF ENSEMBLE MEAN AND 00Z NAEFS MEAN MID TO LATE NEXT WEEK.
OTHER WEATHER GRIDS WILL BE MORE HEAVILY ENSEMBLE MEAN BASED TO
REFLECT FORECAST UNCERTAINTY.  THE DAYS 4-7 QPF WILL START OUT AS
A COMPROMISE OF THE 06Z GFS/00Z ECMWF, WITH SOME 12Z GFS THROWN IN
MIDDAY IF ITS MASS FIELDS LOOK REASONABLE.


WEATHER HIGHLIGHTS/THREATS
~~~~~~~~~~~~~~~~~~~~~~~~~~
THE LEAD SYSTEM IN THE EAST/NORTHEAST WILL LIKELY TRANSPORT
SIGNIFICANT MOISTURE FROM THE TROPICS/SUBTROPICS NORTH THEN
NORTHWEST INTO MILD AIR FOR THIS TIME OF THE YEAR FOR AN ARRAY OF
WINTRY PRECIPITATION TYPES. INGREDIENTS ARE THERE FOR AN INTERIOR
EVENT THANKS TO WARMER TEMPERATURES ALOFT IMPORTED BY THIS SYSTEM
AND A CANADIAN HIGH PRESSURE TO THE NORTH KEEPING COOLER AIR AT
THE SURFACE.  AN UPSTREAM KICKER WILL ENSURE THIS ONE WILL NOT
LINGER BUT PRECIPITATION RATES COULD BE IMPRESSIVE.

SIGNIFICANT PRECIPITATION SHOULD DIMINISH IN THE WEST AND INTERIOR
WEST BY MIDWEEK AS THE UPPER TROUGH SWINGS INTO THE PLAINS.
WIDESPREAD MOUNTAIN SNOWS FROM THE SIERRAS TO THE WASATCH AND THE
MOGOLLON RIM TO THE COLORADO ROCKIES SHOULD WIND DOWN TUESDAY INTO
WEDNESDAY AS THE SURFACE LOW ORGANIZES OVER KANSAS AND LIFTS
NORTHEASTWARD. SNOW WILL EXPAND TO THE NORTHEAST ON THE NORTH SIDE
OF THE LOW WHERE SIGNIFICANT ACCUMULATIONS ARE POSSIBLE. AXIS OF
HEAVIEST QPF SHOULD BE NEAR THE NE/SD BORDER INTO SOUTHERN WI.

BY LATER IN THE WEEK, PATTERN BECOMES QUIET AS THE FRONT SETTLES
INTO FLORIDA AND HIGH PRESSURE IS 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 DOWN.  MILD
TEMPERATURES IN THE EAST SHOULD TREND BACK TOWARD CLIMATOLOGY AS
TROUGHING INCREASES ACROSS THE AREA. LAKE EFFECT SNOW PRODUCTION
WILL PICK UP THURSDAY/FRIDAY WITH NORTH/NORTH-NORTHWEST FLOW.

ROTH/FRACASSO
$$





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