Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4
000
FXUS02 KWBC 101527
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1027 AM EST WED FEB 10 2016

VALID 12Z SAT FEB 13 2016 - 12Z WED FEB 17 2016

...RECORD COLD FOR PORTIONS OF THE NORTHEAST THIS WEEKEND...
...POTENT WINTER STORM POSSIBLE NEXT TUE-WED IN THE EAST...

...OVERVIEW...
FOR THE EAST PAC...PACIFIC NORTHWEST AND SOUTHWEST---A RIDGE OF
HIGH PRESSURE ANCHORED OVER THE GREAT BASIN MAINTAINS A DRY AND
MILD PATTERN--- AND STEERS A SERIES OF PROGRESSIVE NORTHEAST
PACIFIC SYSTEMS INTO THE PACIFIC NORTHWEST...BRITISH COLUMBIA AND
DOWNSTREAM ACROSS THE ROCKY MOUNTAINS FROM WYOMING/MONTANA
NORTHWARD INTO CENTRAL ALBERTA.

DOWNSTREAM...THE WEST-TO-NORTHWEST FLOW PATTERN EXITING THE ROCKY
MOUNTAINS SPREADS EASTWARD INTO THE CENTRAL PLAINS AND GREAT LAKES
AND BEGINS TO INTERACT WITH AND DISPLACE (ERODE) --- THE WESTERN
PERIPHERY OF A COLD TROUGH IN THE EASTERN PORTION OF THE NORTH
AMERICAN CONTINENT.

DEEP AND COLD --- UPPER-LEVEL TROUGH AND SURFACE HIGH IN THE EAST
ON DAYS 3-4 WILL GRADUALLY MODIFY AND BECOME `ENTANGLED` WITH
SEVERAL SHORTWAVES APPROACHING FROM THE WEST. A KEY FEATURE OF
THIS `ENTANGLEMENT` IS THE EMERGENCE OF A SOUTHERN STREAM
SHORTWAVE MIGRATING ACROSS THE NORTHERN GULF COAST AND SOUTHEAST
--- AND ITS INTERACTION WITH THE NORTHERN STREAM FLOW AND
MID-LEVEL ENERGY WITH ORIGINS IN THE NORTHEAST PACIFIC AND WEST
CENTRAL CANADA --- CREATES THE POTENTIAL FOR WINTER WEATHER ACROSS
THE NORTHEAST QUARTER OF THE NATION (DAYS 5-7). HENCE...MAINTAINED
THE HEADLINES FROM THE MIDSHIFT.

...MODEL PREFERENCES...
HAVE NO CONCERN WITH THE DAY3-4 DETAILS EMBEDDED WITHIN THE LEAD
PACIFIC WAVE ENERGY AND SOLUTIONS THAT ALLOW THE MAJORITY OF THE
VORTICITY TO SHEAR EASTWARD --- AND EAST OF THE CONTINENTAL DIVIDE
(ACROSS THE ENTIRE STRETCH OF THE MISSOURI AND PLATTE RIVER
VALLEYS). THE 10/00Z UKMET REALLY IS THE ONLY SOLUTION THAT
CONTINUES TO PROJECT A `WEST OF THE DIVIDE` STORM TRACK SOLUTION
--- AND IS A SOUTHERN OUTLIER OVER THE FOUR CORNERS FOR A SECOND
00Z CYCLE IN A ROW. BECAUSE IT IS A `FOUR CORNERS` SOLUTION --- IT
WILL CERTAINTY MAINTAIN A MORE VOLATILE AND AGGRESSIVE SOLUTION
ACROSS THE SOUTHERN PLAINS. THE EVOLVING FLOW PATTERN DOWNSTREAM
SEEMS TO `DEBUNK` THE AGGRESSIVE UKMET APPROACH MID-PERIOD.

DO HAVE TO GO WITH A 10/00Z ECENS...NAEFS AND GEFS BLEND (50/30/20
WEIGHTING) AFTER 15/00Z DUE TO THE DETERMINISTIC VARIANCE AT
500MB...SURFACE AND ALIGNMENTS OF THE PRECIPITATION DISTRIBUTIONS
ALONG AND EAST OF THE MISSISSIPPI/OHIO VALLEYS. THIS DOES NOT
ALTER THE NATURE OF THE PREVIOUS WPC DAY3-7 SYNOPTIC FRONTS ---
EAST OF THE MS RIVER --- BUT THIS PACKAGE DOES EMPHASIZE A SLIGHT
ADJUSTMENT TO THE SPACING OF THE PRIMARY FEATURES WEST OF THE
MISSISSIPPI AND NORTH OF THE PLATTE RIVER VALLEYS.

...UNCERTAINTY ASSESSMENT...
THE 10/00Z FORECAST CYCLE OFFERS SOME VERY DIFFERENT APPROACHES
(SOLUTIONS) FOR THE DAY 4-6 SYNOPTIC-SCALE SYSTEM ANTICIPATED TO
MIGRATE --- FROM THE MS VALLEY/GREAT LAKES TO THE MID-ATLANTIC
REGION AND NORTHEAST COAST. THE 10/00Z DETERMINISTIC GFS/CANADIAN
AND ECMWF SEEMED TO BE IN DECENT AGREEMENT (INVOF THE OZARKS)
UNTIL 15/00Z BEFORE THE 10/00Z GFS ALLOWS A NORTHERN STREAM
SHORTWAVE TO BECOME THE MORE DOMINANT SYNOPTIC-SCALE ENTITY IN THE
FLOW. THE RESULT BEING...MORE OF A POSITIVE-TILT TROUGH AXIS
(ALBEIT A BRIEF ONE) ALONG THE EAST COAST BY 17/00Z. THIS
SOLUTION...BUT MORE SO---THE 10/00Z UKMET SEEM TO BE THE LEAST
LIKELY DETERMINISTIC SCENARIOS.

THAT SAID...THE 10/00Z DETERMINISTIC CANADIAN/ECMWF...10/00Z
GFS-PARALLEL AND 10/06Z DETERMINISTIC GFS (OPERATIONAL RUN) SEEM
TO BE THE BETTER REPRESENTATIONS HEADING INTO DAY 6. GIVEN THE
10/00Z ENSEMBLE GUIDANCE SCENARIO --- AND THEIR PROJECTIONS FOR
MID-LEVEL TROUGH AMPLITUDE EXITING THE EASTERN SEABOARD --- THE
10/00Z AND 10/06Z CYCLES (DETERMINISTIC VIEWPOINT) BEYOND DAY 5
AND HEADING INTO DAY 6 SEEMED TO BE "FAR FROM A PERFECT PROG SNAP
SHOT". LACKING THE RUN-TO-RUN CONTINUITY OVER THE GREAT LAKES AND
NEW ENGLAND AFTER 16/00Z (LATE DAY 5) --- THIS POINTS TO A BLEND
OF THE 10/00Z GEFS...ECENS AND NAEFS ENSEMBLE MEANS FOR DAY 6-7
...AND TO MANUALLY ADJUST THE UPSTREAM SPACING FROM THE COLUMBIA
BASIN EASTWARD INTO THE DAKOTAS.

...SENSIBLE WEATHER HIGHLIGHTS...
PREVAILING CHILL LINGERS ACROSS THE EASTERN THIRD OF THE NATION
HEADING INTO MONDAY MORNING ---AND THE COLD CANADIAN SURFACE RIDGE
IS STUBBORNLY RETREATING (NORTHEASTWARD) ALONG THE NORTHEAST COAST
AND GULF OF MAINE---EVEN OUT TO DAY 5-6. BECAUSE OF THE STUBBORN
SURFACE RIDGE AND ENTRAINMENT OF MOISTURE AND ENERGY ALONG THE
SOUTHERN AND WESTERN FLANKS (AND ATOP) THIS RIDGE--- EXPECT SOME
LOCALLY MODERATE-TO-HEAVY CONCENTRATIONS OF OVER-RUNNING
PRECIPITATION (AND WINTRY P-TYPE SCENARIOS) WITH EMBEDDED ENERGY
APPROACHING FROM TWO DIRECTIONS...THE GREAT LAKES (A MID-LEVEL
FOCUS) AND THE NORTHEAST GULF OF MEXICO (A LOW-LEVEL FOCUS).

MORE MILD AND DRY ACROSS THE SOUTHWEST --- SHOULD CONTINUE THROUGH
MOST OF THIS FORECAST PERIOD AND THE SCENARIO FOR A SPLITTING
UPPER-LEVEL TROUGH DOWNSTREAM ALONG A MAJOR PORTION OF THE
CONTINENTAL DIVIDE --- MAY PRODUCE SOME PRECIPITATION AND
ADDITIONAL CLOUDINESS AND WINDS ALONG THE WESTERN SIDE---BUT WILL
PRIMARILY BECOME A FORECAST CHALLENGE FOR TEMPERATURES (EAST SIDE
OF THE DIVIDE).

VOJTESAK





$$




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