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Prognostic Meteorological Discussion
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FXUS21 KWNC 191933
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 19 2013

SYNOPSIS: EARLY IN THE PERIOD A SERIES OF SURFACE LOWS ARE PREDICTED TO DEVELOP
ALONG A FRONTAL SYSTEM LOCATED OVER THE PLAINS, THEN TRACK NORTHWARD TOWARDS
CENTRAL CANADA, BRINGING WET WEATHER TO SOME OF THOSE AREAS. ONSHORE FLOW
AROUND AN AREA OF SURFACE HIGH PRESSURE CENTERED NEAR THE MID-ATLANTIC IS
EXPECTED TO CAUSE UNSETTLED WEATHER FOR PARTS OF FLORIDA. LOW PRESSURE AND A
FRONTAL SYSTEM ARE ANTICIPATED TO APPROACH THE PACIFIC NORTHWEST. DEEP SURFACE
LOW PRESSURE IS FORECAST TO MOVE ACROSS THE ALEUTIANS TO THE GULF OF ALASKA,
WHILE AN AREA OF STRONG UPPER-LEVEL HIGH PRESSURE IS PREDICTED FOR THE
NORTHEASTERN PART OF THE STATE. LATER IN THE PERIOD, THE FRONTAL SYSTEM
APPROACHING THE PACIFIC NORTHWEST IS EXPECTED TO COME ONSHORE ALONG THE
NORTHERN HALF OF THE WEST COAST. MONSOONAL FLOW IS EXPECTED TO BECOME
ESTABLISHED OVER THE SOUTHWEST. UPPER-LEVEL HIGH PRESSURE IS FORECAST TO EXPAND
WESTWARD OVER ALASKA.

HAZARDS

HEAVY RAIN FOR PARTS OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES, SAT, JUN
22.

HEAVY RAIN FOR PARTS OF NORTHWESTERN CALIFORNIA, AND WESTERN SECTIONS OF OREGON
AND WASHINGTON, MON-TUE, JUN 24-25.

HIGH WINDS FOR PARTS OF THE ALEUTIANS AND SOUTHWESTERN ALASKA, SAT, JUN 22.

MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF NORTHEASTERN ALASKA, SAT, JUN 22.

FLOODING ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY, NORTH DAKOTA, AND
TEXAS.

SEVERE DROUGHT FOR PARTS OF THE GREAT PLAINS, RIO GRANDE VALLEY, ROCKIES,
SOUTHWEST, GREAT BASIN, CALIFORNIA, AND HAWAII.

DETAILED SUMMARY

FOR SATURDAY JUNE 22 - WEDNESDAY JUNE 26: A SERIES OF SURFACE LOWS ARE FORECAST
TO TRACK NORTHWARD FROM THE HIGH PLAINS TO CENTRAL CANADA DURING THIS PERIOD,
BRINGING HEAVY RAIN TO PARTS OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES
SATURDAY JUNE 22.



ONSHORE FLOW AROUND AN AREA OF SURFACE HIGH PRESSURE CENTERED NEAR THE
MID-ATLANTIC IS EXPECTED TO CAUSE RAINFALL FOR PARTS OF FLORIDA. PRECIPITATION
AMOUNTS ARE NOT CURRENTLY EXPECTED TO REACH HAZARDOUS CRITERIA. THIS FLOW
PATTERN IS ALSO EXPECTED TO CAUSE WARMER THAN NORMAL TEMPERATURES FOR PARTS OF
THE CENTRAL PLAINS BUT MODEL UNCERTAINTY PRECLUDES THE SPECIFICATION OF A
HAZARD AREA AT THE CURRENT TIME.



A SURFACE LOW PRESSURE SYSTEM AND ASSOCIATED FRONT ARE PREDICTED TO APPROACH
THE PACIFIC NORTHWEST COAST. STRONG ONSHORE FLOW ASSOCIATED WITH THIS STORM
SYSTEM IS EXPECTED TO BRING HEAVY RAIN TO PARTS OF THE PACIFIC NORTHWEST AND
EXTREME NORTHWESTERN CALIFORNIA MONDAY TO TUESDAY JUNE 24-25.



A DEEP, SURFACE LOW-PRESSURE SYSTEM MOVING FROM THE ALEUTIANS TO THE GULF OF
ALASKA IS EXPECTED TO CAUSE HIGH WINDS FOR PARTS OF THE EASTERN ALEUTIANS AND
SOUTHWESTERN ALASKA, SATURDAY JUNE 22. AN AMPLIFIED UPPER-LEVEL RIDGE OVER
ALASKA IS EXPECTED TO BRING MUCH ABOVE NORMAL TEMPERATURES FOR MUCH OF THE
NORTHEASTERN PART OF THE STATE SATURDAY JUNE 22.



THE MIDDLE MISSISSIPPI VALLEY, NORTH DAKOTA, AND TEXAS CONTINUE TO BE AREAS
THAT ARE THE FOCUS FOR ONGOING RIVER FLOODING.

FOR THURSDAY JUNE 27 - WEDNESDAY JULY 03: TROPICAL STORM BARRY IS LOCATED OVER
THE BAY OF CAMPECHE AND NHC EXPECTS IT TO TRACK INTO SOUTHEASTERN MEXICO BY
THURSDAY JUNE 20. THIS STORM IS NOT EXPECTED TO HAVE ANY DIRECT IMPACTS TO THE
CONUS AT THIS TIME, BUT MAY SUPPLY MOISTURE NORTHWARD INTO MEXICO AND TEXAS,
WHICH MAY ENHANCE PRECIPITATION ACROSS TEXAS AND THE SOUTHWEST AROUND THE TIME
OF THE ONSET OF THE NORTH AMERICAN MONSOON.



THE MJO IS FORECAST TO STRENGTHEN AND BECOME MORE COHERENT ACROSS THE WESTERN
PACIFIC AND TRAVERSE THE EASTERN PACIFIC DURING THE COMING WEEKS, WHICH MAY
ENHANCE RAINFALL IN THE SOUTHWEST ASSOCIATED WITH THE NORTH AMERICAN MONSOON.



IN GENERAL, AN UPPER-LEVEL RIDGE IS PREDICTED TO BUILD ACROSS THE WEST-CENTRAL
CONUS AND MUCH OF EASTERN ALASKA DURING THIS PERIOD, BRINGING ABOVE-NORMAL
TEMPERATURES TO MANY PARTS OF THE NORTHERN HALF AND WESTERN CONUS, AND ALASKA.
AN UPPER-LEVEL TROUGH IS ANTICIPATED TO DEVELOP OVER THE EASTERN THIRD OF THE
CONUS, BRINGING ABOVE-MEDIAN PRECIPITATION TO THE AREA.

FORECASTER: RANDY SCHECHTER

$$
National Weather Service Weather Forecast Office
