Prognostic Meteorological Discussion
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FXUS21 KWNC 231926
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 23 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 ALONG THE WEST COAST FROM NORTHERN CALIFORNIA TO THE CANADIAN
BORDER, MON-WED, OCT 27-29.

HIGH WINDS ACROSS THE UPPER MIDWEST, GREAT LAKES, AND MID-ATLANTIC, SUN, OCT 26.

HIGH WINDS ACROSS NEW ENGLAND, MON, OCT 27.

HEAVY RAIN AND SNOW FOR NORTHERN IDAHO, TUE-WED, OCT 28-29.

HIGH WINDS AND SIGNIFICANT WAVES FOR THE WESTERN ALASKAN COAST, SUN-MON, OCT
26-27 AND THEN AGAIN WED-THU, OCT 29-30.

HIGH WINDS AND SIGNIFICANT WAVES FOR THE SOUTHWESTERN ALASKAN COAST, WED-THU,
OCT 29-30.

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

DETAILED SUMMARY

FOR SUNDAY OCTOBER 26 - THURSDAY OCTOBER 30: A STRONG UPPER-LEVEL TROUGH IS
FORECAST TO MOVE THROUGH SOUTHERN CANADA AND AMPLIFY AS IT MOVES PAST THE GREAT
LAKES AND THE NORTHEAST.  ITS ASSOCIATED SURFACE LOW IS THEN EXPECTED TO
STRENGTHEN AND INCREASE THE PRESSURE GRADIENT AROUND IT.  THIS STRONG PRESSURE
GRADIENT IS PREDICTED TO LEAD TO HIGH WINDS FOR THE UPPER MIDWEST AND GREAT
LAKES ON THE 26TH AND THE NORTHEAST ON THE 27TH.



CONCURRENTLY, AN UPPER-LEVEL TROUGH IS FORECAST TO MAKE ITS WAY ACROSS THE
LOWER 48.  WARM, MOIST FLOW FROM THE GULF OF MEXICO IS EXPECTED AHEAD OF THE
SURFACE COLD FRONT, LEADING TO SHOWERS AND LOCALLY SEVERE WEATHER.  THE LOW IS
CURRENTLY PREDICTED TO INTENSIFY AS IT NEARS THE GREAT LAKES, WHICH MEANS THE
GREATEST CHANCE FOR HEAVY RAIN AND WIDESPREAD SEVERE WEATHER EXISTS FROM THE
OHIO VALLEY BACK DOWN TO THE LOWER MISSISSIPPI VALLEY ON EITHER TUESDAY THE
28TH OR WEDNESDAY THE 29TH.  ALSO, ON THE BACKSIDE OF THE STORM, ENOUGH COLD
AIR MIGHT EXIST FOR SOME SNOW IN PARTS OF THE DAKOTAS AND UPPER MIDWEST.  AT
THIS TIME, ANY POTENTIAL SNOWFALL DOES NOT APPEAR TO REACH HAZARDOUS CRITERIA,
BUT IS MENTIONED AS IT WOULD BE THE FIRST APPRECIABLE SNOWFALL THIS SEASON FOR
THIS PART OF THE COUNTRY.



THE REMNANTS OF TROPICAL STORM ANA IS THEN EXPECTED TO INTERACT WITH AN
EXTRATROPICAL UPPER-LEVEL TROUGH AND MOVE INTO THE PACIFIC NORTHWEST.  WHILE
THE EXACT DETAILS OF THIS INTERACTION REMAIN UNCERTAIN, THERE IS A GOOD LEVEL
OF CONFIDENCE THAT ANA`S REMNANTS WILL BRING HEAVY RAIN ALONG THE WEST COAST,
FROM NORTHERN CALIFORNIA TO THE CANADIAN BORDER FROM THE 27TH TO THE 29TH.  AN
ADDITIONAL 3 TO 5 INCHES OF RAIN IS POSSIBLE DURING THIS TIME PERIOD.
CONSIDERING THE ALMOST 10 INCHES THAT WILL HAVE FALLEN DURING THE PAST SEVEN
DAYS AS WELL AS BEFORE THIS OUTLOOK PERIOD BEGINS, FLOODING IS A DISTINCT
POSSIBILITY.  THIS MOISTURE IS ALSO PREDICTED TO BRING HEAVY LOW ELEVATION RAIN
AND HIGH-ELEVATION SNOW TO PARTS OF NORTHERN IDAHO.



AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE FROM NORTHEASTERN RUSSIA ACROSS THE
BERING SEA.  THE ASSOCIATED SURFACE LOW IS EXPECTED TO DIRECT HIGH WINDS AND
SIGNIFICANT WAVES TO THE WEST COAST OF ALASKA, FROM ABOUT THE KUSKOKWIM DELTA
TO KOTZEBUE SOUND ON THE 26TH AND 27TH.  CONCURRENTLY, A VERY STRONG STORM IS
FORECAST TO FORM AND MOVE FROM JUST NORTH OF JAPAN INTO THE BERING SEA.  THIS
STORM IS PREDICTED TO BRING ANOTHER ROUND OF HIGH WINDS AND STRONG WAVES TO
MOST OF THE WEST COAST OF ALASKA FROM THE 29TH TO THE 30TH.



FOR FRIDAY OCTOBER 31 - THURSDAY NOVEMBER 06: THERE IS A LOT OF DISAGREEMENT AT
THIS TIME RANGE BETWEEN THE GFS AND OTHER NUMERICAL MODELS.  THE GFS PREDICTS A
STRONG UPPER-LEVEL TROUGH DIGGING DOWN INTO THE MISSISSIPPI VALLEY WITH A
STRONG COASTAL LOW DEVELOPING OFF THE MID-ATLANTIC COAST.  THIS SOLUTION WOULD
BRING HEAVY RAIN TO THE COASTS AND HEAVY SNOW TO THE APPALACHIANS AND GREAT
LAKES.  HOWEVER, OTHER MODELS DO NOT AMPLIFY THE TROUGH THIS DEEPLY, AND
INSTEAD, A SURFACE LOW SKIMS NEW ENGLAND.  THIS WOULD BRING THE POTENTIAL OF
HEAVY SNOW TO MAINE, BUT DUE TO THE UNCERTAINTY, NO HAZARDS ARE INDICATED AT
THIS TIME.



THE MOST RECENT DROUGHT MONITOR, RELEASED OCTOBER 23, SHOWS A SLIGHT DECREASE
IN THE AREAL COVERAGE OF SEVERE DROUGHT, FROM 18.01% TO 18.0%.  THERE IS ALSO
THE LARGEST AMOUNT OF AREAL EXTENT WITHOUT ANY LEVEL OF DRYNESS SINCE DECEMBER
2011.

FORECASTER: KENNETH PELMAN

$$




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