Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXUS21 KWNC 212051
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 21 2014

SYNOPSIS: LOW PRESSURE SYSTEMS ARE PREDICTED TO BRING UNSETTLED WEATHER TO NEW
ENGLAND, THE PACIFIC NORTHWEST, AND SOUTHERN FLORIDA, WHILE THE REST OF THE
LOWER 48 IS EXPECTED TO SEE RELATIVELY CALM WEATHER.  NO COLD AIR OUTBREAKS ARE
EXPECTED, AS THE FLOW IS PREDICTED TO COME PRIMARILY OFF THE PACIFIC OCEAN.

HAZARDS

HEAVY RAIN IN EXTREME SOUTHERN FLORIDA, FRI-SAT, OCT 24-25.

HEAVY RAIN ALONG THE WEST COAST FROM NORTHERN CALIFORNIA TO THE CANADIAN BORDER
FRI-SAT, OCT 24-25 AND THEN AGAIN, MON-TUE, OCT 27-28.

HIGH WINDS ACROSS THE NORTHEAST, FRI, OCT 24 AND MON, OCT 27.

SIGNIFICANT WAVES FOR AREAS AROUND THE SEWARD PENINSULA AND KOTZEBUE SOUND,
FRI, OCT 24.

SEVERE DROUGHT FOR THE CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, SOUTHEAST,
PACIFIC NORTHWEST, GREAT BASIN, AND CALIFORNIA.

DETAILED SUMMARY

FOR FRIDAY OCTOBER 24 - TUESDAY OCTOBER 28: THIS FORECAST PERIOD IS EXPECTED TO
BEGIN WITH A STRONG STORM JUST OFF THE MAINE COAST.  THE STRONG PRESSURE
GRADIENT BETWEEN THIS LOW AND SURFACE HIGH PRESSURE IN EASTERN CANADA IS
PREDICTED TO LEAD TO STRONG WINDS, OF AT LEAST 20 KNOTS, FOR NEW ENGLAND ON
FRIDAY, THE 24TH.  AFTERWARDS, A STRONG UPPER-LEVEL LOW IS FORECAST TO MOVE
ACROSS SOUTHERN CANADA AND MERGE WITH THE COASTAL LOW.  THIS IS EXPECTED TO
INCREASE THE PRESSURE GRADIENT ONCE AGAIN AND LEAD TO ANOTHER DAY OF HIGH
WINDS, ON MONDAY, THE 27TH.



AN AREA OF DISTURBED WEATHER IN THE BAY OF CAMPECHE IS FORECAST TO MAKE ITS WAY
NORTHEASTWARD TOWARDS THE FLORIDA KEYS.  AS OF 2PM ET, ON 10/21, THERE IS A 50%
CHANCE OF THIS DISTURBANCE BECOMING A TROPICAL SYSTEM OVER THE NEXT FIVE DAYS.
WHILE THERE IS UNCERTAINTY IN THE NUMERICAL MODELS AS TO THE EXACT STRENGTH OF
THIS POTENTIAL SYSTEM, MANY AGREE THAT IT BRINGS A SIGNIFICANT CHANCE OF HEAVY
RAIN TO SOUTHERN FLORIDA, INCLUDING THE KEYS, ON THURSDAY AND FRIDAY, THE 24TH
AND 25TH, WITH TOTALS OF 2 TO 4 INCHES LIKELY.  OF COURSE, IF THE SYSTEM
STRENGTHENS SIGNIFICANTLY, WIND AND WAVE HAZARDS WILL HAVE TO BE INTRODUCED IN
FUTURE HAZARDS OUTLOOKS.



THE WEST COAST IS FORECAST TO SEE A NUMBER OF SYSTEMS IMPACTING IT WITH STORMY
WEATHER DURING THIS OUTLOOK PERIOD.  THE FIRST SYSTEM IS AN UPPER-LEVEL TROUGH
DIGGING DOWN SOUTH OF ALASKA.  AS THE TROUGH MAKES ITS WAY INLAND, ENHANCED
SURFACE WINDS ARE POSSIBLE IN PARTS OF THE NORTHERN CALIFORNIA AND NORTHERN
NEVADA.  BECAUSE THESE AREAS ARE ALSO IN LONG-TERM DROUGHT, ANY ENHANCED WINDS
COULD ENHANCE THE RISK OF WILDFIRES.  BECAUSE THE MAGNITUDE OF THE SURFACE
WINDS IS UNKNOWN AT THIS TIME, NO HAZARDS ARE INDICATED ON THE MAP.  ALSO,
STRONG ONSHORE FLOW AT THE SURFACE IS EXPECTED TO LEAD TO HEAVY RAIN FOR THE
WEST COAST, FROM NORTHERN CALIFORNIA TO THE CANADIAN BORDER, BRINGING AN
ADDITIONAL 2 TO 3 INCHES OF RAIN FROM WHAT IS PREDICTED TO FALL BEFORE THIS
OUTLOOK PERIOD BEGINS.



LATER IN THE PERIOD, THE REMNANTS OF TROPICAL STORM ANA ARE EXPECTED TO MERGE
WITH AN UPPER-LEVEL TROUGH SOUTH OF ALASKA AND MOVE TOWARDS THE WEST COAST OF
NORTH AMERICA.  WHILE THERE IS SOME MODEL UNCERTAINTY AS TO WHICH LOCATIONS
WILL RECEIVE THE MOST RAINFALL, THERE IS GOOD AGREEMENT ON PARTS OF THE WEST
COAST GETTING ANOTHER 1 TO 2 INCHES OF RAINFALL.  WITH 5 TO 10 INCHES OF RAIN
POSSIBLE OVER THE NEXT SEVEN DAYS, FLOODING IS ALSO A POSSIBILITY.



A STRONG STORM IS PREDICTED TO IMPACT THE WEST COAST OF ALASKA ON FRIDAY, THE
24TH, BRINGING THE CHANCE OF SIGNIFICANT WAVES.  ALSO, THE POTENTIAL EXISTS FOR
THE SOUTHERN COAST OF ALASKA AND THE ALEUTIANS TO EXPERIENCE STORMY WEATHER
FROM THE INTERACTION OF THE REMNANTS OF TROPICAL STORM ANA WITH AN UPPER-LEVEL
TROUGH, BUT THERE IS CURRENTLY TOO MUCH UNCERTAINTY TO WARRANT A HAZARD.



FOR WEDNESDAY OCTOBER 29 - TUESDAY NOVEMBER 04: BOTH THE GFS AND ECMWF MODELS
ARE PREDICTING STRONG NORTHERLY FLOW IN SOUTHEASTERN PARTS OF THE ALASKAN
MAINLAND. THE GFS HAS DAILY MINIMUM TEMPERATURES 20 DEGREES BELOW NORMAL FOR
THE 29TH AND 30TH.  BECAUSE OF THIS FORECAST, AND AN EXISTING SNOWPACK, A
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES WAS INDICATED ON THE 8-14 DAY
PROBABILISTIC HAZARDS OUTLOOK.



THE MOST RECENT DROUGHT MONITOR, RELEASED OCTOBER 16, SHOWS A SLIGHT DECREASE
IN THE AREAL COVERAGE OF SEVERE DROUGHT, FROM 18.6% TO 18.1%.  THERE IS ALSO
THE LOWEST AMOUNT OF AREAL EXTENT WITHOUT ANY LEVEL OF DRYNESS SINCE DECEMBER
2011.

FORECASTER: KENNETH PELMAN

$$




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