Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Air Quality
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Extended Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0542Z Nov 19, 2014)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1242 AM EST WED NOV 19 2014

VALID 12Z SAT NOV 22 2014 - 12Z WED NOV 26 2014

...PATTERN OVERVIEW...

TO BEGIN THE WEEKEND...A SPLIT FLOW REGIME WILL BE IN PLACE WITH A
SOUTHERN STREAM SYSTEM ADVANCING INTO THE SOUTHERN HIGH PLAINS BY
EARLY SATURDAY. MEANWHILE...THE NORTHERN BRANCH OF THE JET SHOULD
BE MORE RELAXED IN TERMS OF AMPLITUDE WHICH WILL INITIALLY LIMIT
THE SOUTHWARD PROGRESSION OF RENEWED ARCTIC INTRUSIONS. THE
SHORTWAVE ENERGY MIGRATING THROUGH THE SOUTHERN PLAINS ON SATURDAY
IS FORECAST TO LIFT THROUGH THE OZARKS AND EVENTUALLY INTO THE
UPPER GREAT LAKES BY THE END OF THE WEEKEND. THIS SYSTEM IS
EXPECTED TO ATTAIN A NEGATIVE TILT RESULTING IN STRONG
CYCLOGENESIS WITH SURFACE PRESSURES POSSIBLY DROPPING BELOW
980-MB. AS THIS DISTURBANCE LIFTS UP INTO ONTARIO...MODELS AGREE
THAT ADDITIONAL SHORTWAVE ENERGY WILL RACE THROUGH THE
INTERMOUNTAIN WEST AND EVENTUALLY INTO THE GREAT PLAINS. THIS
ULTIMATELY HELPS SET UP A LONGWAVE TROF EXTENDING FROM THE ROCKY
MOUNTAIN REGION EASTWARD TO THE GREAT LAKES BY THE EARLY PART OF
NEXT WEEK. THIS MORE AMPLIFIED FLOW WILL GRADUALLY SHIFT EASTWARD
CARRYING A WELL-DEFINED BAROCLINIC ZONE TOWARD THE EASTERN
SEABOARD. WHILE THIS ASPECT OF THIS FORECAST IS WELL
RESOLVED...THERE IS STILL A LOT OF UNCERTAINTY ACROSS THE EASTERN
PACIFIC/WEST COAST WITH HOW MUCH ENERGY SLIDES INLAND AND
ULTIMATELY CONTROLLING WHETHER A RIDGE HOLDS IN PLACE OR NOT.


...MODEL EVALUATION/WPC PREFERENCES...

FOR DAY 3/SATURDAY...THE MODELS HANDLE THE INITIAL SOUTHERN STREAM
SHORTWAVE RATHER WELL ALTHOUGH THERE ARE SOME SUBTLE DIFFERENCES
IN AMPLITUDE. THE 12Z CMC/UKMET DEPICT A BIT MORE AMPLIFICATION IN
THE FLOW WHICH LEADS TO A MORE SOUTHWARD PLACEMENT OF THE SURFACE
WAVE. BY THE FOLLOWING DAY...MODEL SPREAD BUILDS WITH THE TIMING
OF THIS IMPULSE AS IT LIFTS TOWARD THE LOWER MO VALLEY AND GREAT
LAKES REGION. THE 12Z ECMWF WAS QUICKER THAN ANY PIECE OF GUIDANCE
WITH A MAJORITY OF THE DETERMINISTIC/ENSEMBLE SOLUTIONS FAVORING A
SLOWER FORWARD PROGRESSION. WPC DEFINITELY LEANED THIS WAY IN THE
FORECAST PACKAGE UTILIZING THE 18Z GFS AND THE 00Z ECMWF WITH THE
LATTER BEING SLOWER THAN ITS MORE RECENT MODEL RUN. THE 12Z UKMET
SHOWED A SOLUTION SIMILAR TO THE 18Z GFS/00Z ECMWF PAIRING BUT THE
UKMET WAS MORE AGGRESSIVE ALOFT LEADING TO A MUCH DEEPER CYCLONE
CENTER WHILE ALSO BEING QUICKER WITH THE COLD FRONT. FELT
COMFORTABLE UTILIZING AN EQUAL BLEND OF THE 18Z GFS/00Z ECMWF
THROUGH DAY 5/MONDAY BEFORE LEANING MORE TOWARD THE ENSEMBLE
MEANS. OVERALL RUN-TO-RUN DIFFERENCES BECAME TOO SIGNIFICANT BY
THE EARLY/MIDDLE PART OF NEXT WEEK TO INCORPORATE ANY
DETERMINISTIC PIECE OF GUIDANCE. THE 18Z GEFS/12Z ECMWF ENSEMBLE
MEANS AFFORDED A SIMILAR SOLUTION ACROSS THE EASTERN U.S. WHILE
COMPROMISING WITH THE DETAILS ACROSS THE WEST. AS MENTIONED
EARLIER...THERE IS A GREAT DEAL OF UNCERTAINTY WITH THE UPSTREAM
PATTERN AS THE 18Z/12Z GFS AND 00Z ECMWF FAVOR A RIDGE ACROSS THE
WESTERN U.S. DURING THE MIDDLE OF NEXT WEEK WHILE THE MORE RECENT
12Z ECMWF CARRIES A PRONOUNCED SHORTWAVE INTO THE SOUTHWESTERN
U.S. THE 12Z ECMWF ENSEMBLE MEAN AT LEAST HINTS AT THIS IN ITS
MASS FIELDS. DECIDED TO PLAY THE CONSERVATIVE ROUTE AND BLENDED
50/50 AMONG THE 18Z GEFS/12Z ECMWF ENSEMBLE MEANS FOR DAYS 6 AND
7/TUESDAY AND WEDNESDAY.


...SENSIBLE WEATHER HIGHLIGHTS...

INITIALLY TEMPERATURES WILL BE RATHER CHILLY OVER THE NORTHEASTERN
CORRIDOR OF THE NATION AS A 1036-MB RIDGE IS CENTERED OVER THE
MID-ATLANTIC SATURDAY MORNING. THIS WILL BRING MORNING
TEMPERATURES INTO THE TEENS AND 20S ACROSS THE REGION WHICH BRINGS
DEPARTURES TO AROUND 10 TO 15 DEGREES BELOW NORMAL. AS THE RIDGE
OF HIGH PRESSURE EXITS INTO THE ATLANTIC...RETURN FLOW AROUND THE
ANTICYCLONE WILL AID IN STRONG WARM ADVECTION AHEAD OF THE NEXT
SYSTEM OVER THE CENTRAL U.S. PERSISTENT LOW-LEVEL SOUTHERLY FLOW
IN COMBINATION WITH ABUNDANT CLOUD COVER WILL KEEP MILD OVERNIGHT
TEMPERATURES IN PLACE FROM DAYS 4 TO 6 ACROSS MUCH OF THE SOUTHERN
U.S. AND EVENTUALLY ALONG THE EASTERN SEABOARD. THE CURRENT
FORECAST SUGGESTS READINGS OVER 20 DEGREES ABOVE CLIMATOLOGY FOR
LOW TEMPERATURES GIVEN READINGS IN THE 50S AND POSSIBLY LOWER 60S.
ANOMALIES WILL BE A BIT WEAKER DURING THE DAYTIME BUT STILL RANGE
IN THE 10 TO 15 DEGREE RANGE. ELSEWHERE...THE NEXT UPPER TROF
DIGGING INTO THE CENTRAL U.S. WILL BRING THE NEXT SHOT OF COLD AIR
INTO THE NORTHERN TIER. UNLIKE PREVIOUS OUTBREAKS THIS MONTH...THE
ANOMALIES SHOULD BE MUCH WEAKER.

IN TERMS OF PRECIPITATION...HEAVY RAINFALL IS EXPECTED ALONG AND
AHEAD OF THE STRONG COLD FRONT MIGRATING EASTWARD. THE CURRENT
MODELS SUGGEST THE HEAVIEST AMOUNTS SHOULD BE FROM THE SOUTHERN
PLAINS/LOWER MS VALLEY AND ALONG THE GULF COAST REGION WHERE THE
BETTER MOISTURE FLUXES WILL RESIDE. IT SHOULD BE COLD ENOUGH NORTH
AND WEST OF THE STRONG SURFACE LOW TO SPREAD WINTRY PRECIPITATION
TO THE GREAT LAKES REGION. ACROSS THE WEST...PERSIST ONSHORE FLOW
COMBINED WITH A SERIES OF IMPULSES ALOFT MOVING FROM THE PACIFIC
NORTHWEST INTO THE INTERMOUNTAIN WEST SHOULD BRING AN UNSETTLED
PERIOD TO THIS REGION OF THE COUNTRY. TEMPERATURES APPEAR COLD
ENOUGH TO SUPPORT WIDESPREAD SNOWFALL OVER MUCH OF THE HIGHER
TERRAIN WHILE RAIN IS MORE LIKELY ACROSS THE PACIFIC NORTHWEST
COAST AND VALLEY LOCALES.


RUBIN-OSTER