Prognostic Meteorological Discussion
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FXUS21 KWNC 201929
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 20 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 FOR NEW ENGLAND, THU-FRI, OCT 23-24.

HEAVY RAIN IN EXTREME SOUTHERN FLORIDA, THU-FRI, OCT 23-24.

HEAVY RAIN ALONG THE WEST COAST FROM NORTHERN CALIFORNIA TO THE CANADIAN BORDER
THU-SAT, OCT 23-25 AND THEN AGAIN, MON-TUE, OCT 27-28.

HEAVY PRECIPITATION FOR NORTHERN IDAHO, THU-SAT, OCT 23-25.

HIGH WINDS ACROSS THE NORTHEAST, THU-FRI, OCT 23-24.

HIGH WINDS FOR THE SEWARD PENINSULA, MOST OF KOTZEBUE AND NORTON SOUNDS, AND
ST. LAWRENCE ISLAND, FRI, OCT 24.

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 THURSDAY OCTOBER 23 - MONDAY OCTOBER 27: THIS FORECAST PERIOD IS EXPECTED
TO BEGIN WITH A STRONG STORM JUST OFF THE EAST COAST NEAR CAPE COD.  THIS LOW
IS PREDICTED TO BRING HEAVY RAIN TO PARTS OF MAINE AND HIGH WINDS FOR MUCH OF
NEW ENGLAND.  ADDITIONAL RAIN OF 1-2 INCHES IS POSSIBLE, WHICH WOULD BE IN
ADDITION TO HEAVY RAIN EXPECTED TO FALL BEFORE THIS OUTLOOK PERIOD BEGINS.
THUS, FLOODING IS ALSO A POTENTIAL HAZARD.  SUSTAINED WINDS OF AT LEAST 20
KNOTS ARE ANTICIPATED, DUE TO THE STRONG PRESSURE GRADIENT AROUND THE LOW
PRESSURE SYSTEM.  WINDS WILL LIKELY BE STRONGEST RIGHT ALONG THE MAINE
COASTLINE, AS A STRONG FETCH OFF THE ATLANTIC IS PREDICTED.



AN AREA OF DISTURBED WEATHER IN THE SOUTHERN CARIBBEAN IS FORECAST TO MAKE ITS
WAY NORTHEASTWARD TOWARDS THE FLORIDA KEYS.  AS OF 2PM ET, ON 10/20, THERE IS A
50% CHANCE OF THIS DISTURBANCE BECOMING A TROPICAL SYSTEM.  WHILE THERE IS
UNCERTAINTY IN THE NUMERICAL MODELS AS TO THE EXACT STRENGTH OF THIS POTENTIAL
SYSTEM, ALL 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.  IN ADDITION, HEAVY RAIN AT LOW ELEVATIONS AND HEAVY
SNOW AT HIGH ELEVATIONS IS EXPECTED OVER PARTS OF NORTHERN IDAHO.



LATER IN THE PERIOD, THE REMNANTS OF 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 AND HIGH WINDS.  ALSO, THE
POTENTIAL EXISTS FOR THE SOUTHERN COAST OF ALASKA AND THE ALEUTIANS TO
EXPERIENCE STORMY WEATHER FROM THE INTERACTION OF THE REMNANTS OF ANA WITH AN
UPPER-LEVEL TROUGH, BUT THERE IS CURRENTLY TOO MUCH UNCERTAINTY TO WARRANT A
HAZARD.



FOR TUESDAY OCTOBER 28 - MONDAY NOVEMBER 03: CONTINUED HEAVY RAIN ALONG THE
PACIFIC NORTHWEST COAST IS PREDICTED AT THE BEGINNING OF THIS PERIOD.
AFTERWARDS, THE UPPER-LEVEL PATTERN IS PREDICTED TO FLATTEN OUT, REDUCING THE
CHANCE OF TEMPERATURE AND PRECIPITATION HAZARDS TO ALASKA AND THE LOWER 48.



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

$$




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