Prognostic Meteorological Discussion
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FXUS02 KWBC 200507
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1207 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...


...OVERVIEW...

TRANSITION PERIOD FOR THE CONUS NEXT WEEK AS TWO SYSTEMS LIFT
THROUGH THE EAST AND RIDGING BUILDS INTO THE WESTERN STATES LATER
IN THE WEEK. AFTER A RATHER ACTIVE START, THE WEEK SHOULD END ON
THE QUIET SIDE WITH BROAD CYCLONIC UPPER FLOW OVER THE EASTERN
HALF OF THE LOWER 48.

...GUIDANCE EVALUATION AND PREFERENCES...

THE MODELS HAVE LARGELY SETTLED DOWN FROM PREVIOUS SHIFTS IN
TRACK/INTENSITY OF THE LEAD EASTERN SYSTEM AND TRAILING PLAINS
SYSTEM, THOUGH STILL DIFFER SOMEWHAT FROM THE ENSEMBLE MEANS. IN
THE NORTHEAST, THE DETERMINISTIC GFS/ECMWF/UKMET/CANADIAN ALL LIED
JUST TO THE NORTHWEST OF THEIR ENSEMBLE MEANS ON TUESDAY AS THE
SFC LOW SHOULD PASS OVER OR NEAR CAPE COD. UKMET WOBBLED MOST FROM
THE OTHERS BUT PROVIDED A BIT OF A BALANCE TO THE GFS. GENERALLY A
DETERMINISTIC CONSENSUS CAN FORESHADOW A SUBSEQUENT ENSEMBLE SHIFT
AND USED A BLEND OF SUCH FOR MON-WED. FOR THE PLAINS SYSTEM, AGAIN
THE MODELS HAVE CONVERGED ON A COMMON SOLUTION TAKING THE LOW NEAR
CHICAGO (A FAVORED PATHWAY) WEDNESDAY MORNING. ENSEMBLE MEANS WERE
WITHIN THE DETERMINISTIC CLUSTER THOUGH RECENT INCONSISTENCIES IN
THE GUIDANCE AND LINGERING ENSEMBLE SPREAD SUGGEST THE EVENTUAL
TRACK MAY SHIFT AGAIN. NEVERTHELESS, CONSENSUS IS HARD TO BEAT AT
THIS POINT.

IN THE WEST, ONCE THE UPPER LOW (THAT WILL HELP DEVELOP THE PLAINS
SYSTEM) PASSES EAST OF THE ROCKIES, HEIGHTS WILL BUILD IN A HURRY
INTO THE PACIFIC NORTHWEST FOR THE REST OF THE WEEK. THIS WILL CUT
OFF MOST OF THE PRECIP TO THE WEST OUTSIDE THE ROCKIES LATER NEXT
WEEK. DETERMINISTIC RUNS TRY TO LOFT A SHORTWAVE UP AND OVER THE
RIDGE (SEEN AS A WEAKENING SFC FRONT) BUT EFFECTS SHOULD BE
MINIMAL.


...WEATHER HIGHLIGHTS/THREATS...

LEAD SYSTEM IN THE EAST/NORTHEAST WILL LIKELY TRANSPORT A LOT OF
MOISTURE FROM THE SUBTROPICS NORTHWARD THEN NORTHWESTWARD INTO
MARGINALLY COLD AIR (CONSIDERING IT IS JANUARY) FOR A VARIETY OF
PRECIPITATION TYPES. INGREDIENTS ARE THERE FOR AN INTERIOR EVENT
THANKS TO AN OVERALL MILD ATMOSPHERE BUT CONTRASTED WITH CANADIAN
HIGH PRESSURE TO THE NORTH. UPSTREAM SYSTEM WILL ENSURE THIS ONE
WILL NOT STICK AROUND BUT PRECIPITATION RATES COULD BE IMPRESSIVE.

FROM WEST TO EAST... 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 PER THE ENSEMBLES LIES ALONG THE
NE/SD BORDER TO THE MN/IA BORDER.

BY LATER IN THE WEEK, PATTERN BECOMES QUIET AS THE FRONT SETTLES
INTO FLORIDA AND HIGH PRESSURE CONTROLS THE WEST. DESPITE THE
HIGHER 500MB HEIGHTS, WARMING WILL GENERALLY NOT BE REALIZED
ALONG/WEST OF THE DIVIDE WITH A NORTHERLY UPPER FLOW AND 700MB
TEMPS ABOUT 1-2 STND DEV BELOW AVG. MILD TEMPERATURES IN THE EAST
SHOULD TREND BACK TOWARD CLIMATOLOGY AS TROUGHING SETTLES IN. IN
ADDITION, LAKE EFFECT SNOW WILL PICK UP THU/FRI WITH N/NNW FLOW.


FRACASSO

$$




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