Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 042130
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
230 PM PDT WED MAY 4 2016

.SHORT TERM...TONIGHT THROUGH FRIDAY...A LARGE AND ROBUST UPPER
TROUGH OFF THE COAST IS PRODUCING A SOUTHERLY FLOW OVER THE FORECAST
AREA AND REGION. THIS IS BRINGING UP MOISTURE AND INSTABILITY FROM
THE SOUTH INTO THE CWA. SEVERAL STORMS HAVE ALREADY DEVELOPED ALONG
THE CASCADES AND SOUTH OF THE DESCHUTES COUNTY. SO FAR THESE HAVE
BEEN MODERATE TO STRONG STORMS WHICH REQUIRED A FEW STATEMENTS TO BE
ISSUED BY MFR. ONE STORM IS MOVING INTO DESCHUTES COUNTY AT THIS
TIME AND MAY NEED TO ISSUE A STATEMENT FOR IT. IT DOES NOT LOOK
SEVERE...BUT COULD BE STRONG. MORE STORMS ARE EXPECTED TO FORM AND
WILL HAVE A CHANCE OF THUNDERSTORMS FOR THE SOUTHERN AND EASTERN
AREAS OF THE CWA THIS EVENING AND A SLIGHT CHANCE OF STORMS OVER THE
NORTHWEST PORTION WHERE IT WILL NOT BE AS UNSTABLE. CONVECTIVE
PARAMETERS ARE FAVORABLE FOR THUNDERSTORMS SUCH AS PWAT...NEGATIVE
LI AND DEW POINTS. SHEAR IS PRETTY WEAK SO ORGANIZED CONVECTION IS
NOT EXPECTED THIS EVENING. ON THURSDAY THE ATMOSPHERE WILL BECOME
EVEN MORE UNSTABLE IN THIS SOUTHERLY FLOW ALOFT AND THE ATMOSPHERE
WILL BE MORE MOIST AS WELL. SPC HAS A MARGINAL RISK OF SEVERE STORMS
OVER THE NORTHEAST CORNER OF THE CWA WHERE THE ATMOSPHERE WILL BE
THE MOST UNSTABLE AND MOIST. THE ONLY FLY IN THE OINTMENT IS THAT
THERE WILL BE PLENTY OF CLOUDS AROUND WHICH MAY INHIBIT CONVECTION.
NEVERTHELESS IT STILL LOOKS LIKE A BUSY DAY WITH THUNDERSTORMS. MAY
NEED EXTRA STAFFING DURING THE EVENING SHIFT AS A RESULT. CONDITIONS
WILL BECOME A LITTLE MORE STABLE ON FRIDAY BUT THERE WILL STILL BE A
CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS OVER THE SOUTHEAST
HALF OF THE CWA AS A NORTHEAST WRAP AROUND FLOW PULLS MOISTURE AND
INSTABILITY INTO THE CWA AROUND A LARGE UPPER LOW OVER THE SOUTHERN
GREAT BASIN WITH NORTHEAST WINDS. THESE ARE NOT TYPICAL WINDS
ASSOCIATED WITH THUNDERSTORMS SO THIS WILL NEED TO BE RE-EVALUATED.
HOWEVER CONVECTIVE INDICES INDICATE THAT THERE WILL BE MORE
CONVECTION ON FRIDAY. TEMPERATURES WILL COOL ON THURSDAY DUE TO MORE
CLOUD COVER BUT THEN WILL WARM BACK UP INTO THE LOWER 80S IN THE
LOWER ELEVATIONS WITH 60S AND 70S IN THE MOUNTAINS IN TIME FOR THE
WEEKEND. 88

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY. A LOW PRESSURE
SYSTEM TO OUR SOUTH WILL CONTINUE TO PUMP MOISTURE NORTH AND INTO
OUR AREA THIS WEEKEND. THUS LATE AFTN AND EARLY EVE TSRA SHOULD
DEVELOP FRI AND AGAIN ON SATURDAY MOSTLY OVER OUR EASTERN ZONES. A
FEW SHOWERS LINGER ALONG THE EASTERN MOUNTAINS SUNDAY BUT AS THE LOW
PRESSURE SYSTEM SLOWLY MOVES AWAY...A RIDGE OF HIGH PRESSURE BUILDS
INTO THE TWO STATE AREA SUNDAY NIGHT AND MONDAY. DRIER CONDITIONS
CAN BE EXPECTED FOR THE ENTIRE REGION NEXT WEEK. TEMPERATURES WILL
REMAIN SLIGHTLY ABOVE NORMAL ALTHOUGH COOLER TEMPS CAN BE EXPECTED
MONDAY THROUGH WEDNESDAY.

&&

.AVIATION...MAINLY VFR CONDITIONS WILL PERSIST BUT THUNDERSTORMS
WILL DEVELOP INTO THE EVENING AND MAY APPROACH ANY TAF SITE TONIGHT
AND BRIEF WIND GUSTS TO 35 KTS IS POSSIBLE WITH ANY STORM. TSRA
SHOULD DECREASE IN COVERAGE AROUND 06Z. AFTERWARDS SHOWERS SHOULD
PERSIST INTO THURSDAY MORNING BEFORE DAYTIME HEATING THURSDAY AFTN
COULD PRODUCE ISOLD TSRA ONCE AGAIN.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  76  54  81 /  60  50  30  20
ALW  56  76  56  82 /  50  50  40  20
PSC  54  78  54  83 /  50  40  30  10
YKM  51  78  51  84 /  60  30  20  10
HRI  51  76  51  81 /  50  40  30  10
ELN  48  74  48  81 /  60  30  20  10
RDM  42  67  42  74 /  70  60  30  20
LGD  45  71  45  74 /  50  60  60  30
GCD  47  71  47  72 /  50  70  70  30
DLS  51  76  51  84 /  60  40  20  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

88/97/97



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