Prognostic Meteorological Discussion
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000
FXUS02 KWBC 181332
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
831 AM EST WED JAN 18 2017

VALID 12Z SAT JAN 21 2017 - 12Z WED JAN 25 2017

GENERAL FLOW PATTERN/GUIDANCE EVALUATION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A BURGEONING POSITIVE ANOMALY ACROSS EASTERN CANADA FAVORS CLOSED
CYCLONES MOVING UNDER ITS BASE NEAR THE 40TH PARALLEL, WHICH IS
SEEN WITHIN THE AVAILABLE GUIDANCE.  OVERALL, THE GUIDANCE IS
QUITE AGREEABLE AND IN BETTER THAN AVERAGE AGREEMENT.  DETAIL
ISSUES REMAIN, AS USUAL.  TO DEAL WITH THESE, STARTED WITH THE
BLEND OF THE 00Z ECMWF, 00Z UKMET, 00Z CANADIAN, AND 06Z GFS FOR
THE SURFACE PRESSURES, FRONTS, AND 500 HPA HEIGHTS EARLY ON BEFORE
INCLUDING INCREASING AMOUNTS OF THE 00Z NAEFS MEAN AND 00Z ECMWF
ENSEMBLE MEAN SOLUTIONS.  THE TEMPERATURES, RAIN CHANCES, CLOUD,
WEATHER, AND DEW POINT GRIDS WILL BE MORE ENSEMBLE MEAN-HEAVY, AS
USUAL.  THE DAYS 4-7 QPF IS EXPECTED TO BE BASED ON A COMPROMISE
OF THE 00Z ECMWF/06Z GFS EARLY ON BEFORE LEANING MORE IN THE GFS
DIRECTION LATE AS IT AND THE CANADIAN MODEL APPEAR TO BE HANDLING
THE SYSTEM MOVING FROM THE EAST OUT INTO THE WESTERNMOST ATLANTIC
BETTER THAN THE OPERATIONAL ECMWF RUN.


WEATHER THREATS
~~~~~~~~~~~~~~~

WEST/PLAINS
~~~~~~~~~~~
THE MOST PRONOUNCED EFFECTS OF PACIFIC SYSTEMS SHOULD BE IN THE
SATURDAY NIGHT-MONDAY TIME FRAME.  THE HEAVIEST RAIN/HIGH
ELEVATION SNOWS SHOULD FIRST ARRIVE AT THE CENTRAL WEST COAST
BEFORE SHIFTING SOUTHWARD WITH TIME WITH THE BEST ONSHORE FLOW.
FAVORED COASTAL LOCATIONS AND SIERRA NEVADA RANGE MAY SEE UP TO
SEVERAL INCHES OF LIQUID EQUIVALENT PRECIPITATION.  STRONGEST
WINDS WILL LIKELY AFFECT THE CNTRL-NRN WEST COAST SATURDAY
NIGHT-SUNDAY. HIGHS WILL BE BELOW NORMAL OVER MUCH OF THE WEST
DURING THE PERIOD WITH SOME AREAS MORE THAN 10F COLDER THAN AVG ON
ONE OR MORE DAYS. AS THIS SYSTEM TRACKS NORTHEAST ACROSS THE
PLAINS, THERE WILL LIKELY BE A BAND OF SNOW TO THE NW OF THE LOW
TRACK.  THE PLAINS WHICH WILL BEGIN TO SEE SOME OF THE COOLER AIR
MOVE IN FROM THE WEST BY TUESDAY-WEDNESDAY. THE FCST IS CONSISTENT
WITH THE UPPER MS VALLEY REGION SEEING MULTIPLE DAYS OF MORNING
LOWS 30-40F ABOVE NORMAL WITH SOME RECORD WARM MINS.

SOUTHEAST/EAST
~~~~~~~~~~~~~~
AS THIS SYSTEM CROSSES THE CENTRAL AND EASTERN STATES, IT WILL BE
ACCOMPANIED BY A BROAD SHIELD OF PRECIPITATION WITH THE HEAVIEST
RAINS EXPECTED FROM THE EASTERN GULF COAST NORTHEAST ALONG THE
APPALACHIANS/EAST COAST.  CONSULT SPC OUTLOOKS FOR LATEST INFO
REGARDING POTENTIAL SEVERE WEATHER ALONG THE GULF COAST DURING THE
WEEKEND.  RAIN OVER THE EAST COAST STATES WILL BE ENHANCED BY
STRONG ATLANTIC INFLOW, BUT INSTABILITY SHOULD BE MINIMAL THE
FARTHER YOU GO NORTHWARD.  A RELATIVE MAXIMUM IN PRECIPITATION IS
ALSO EXPECTED FROM THE SOUTH-CENTRAL PLAINS INTO THE LOWER OH
VALLEY WITH A SYSTEM TAPPING LESSER AMOUNTS OF MOISTURE AS THE
POLAR FRONT REMAINS FARTHER SOUTHWARD.  PRECIPITATION TYPE STILL
LOOKS TO BE NEARLY ALL RAIN WITH ANY WINTRY WEATHER (SNOW AND
FREEZING RAIN) CONFINED TO NEW ENGLAND... AND LOCALLY WITH UPPER
LOWS.  ABOVE TO MUCH ABOVE NORMAL TEMPERATURES ASIDE FROM THE FL
PENINSULA ARE EXPECTED AFTER A WARM WEEKEND.

ROTH/RAUSCH
$$




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