000
FXUS63 KBIS 161820
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
120 PM CDT THU MAY 16 2013

.UPDATE...
ISSUED AT 120 PM CDT THU MAY 16 2013

CURRENT LOCAL RADAR SHOWS A LARGE AREA OF LIGHT TO MODERATE RAIN
SHOWERS FROM NEAR VELVA...TO BEULAH...AND SOUTH TO HETTINGER. THIS
IS MOVING EAST/NORTHEAST AND HAVE BUMPED POPS TO CATEGORICAL FOR THE
AFTERNOON...TAPERING FROM WEST TO EAST. LOWERED MAX TEMPS A BIT DUE
TO CLOUDS AND RAIN OVER SOUTH CENTRAL/SOUTHEAST NORTH DAKOTA.
SATELLITE IMAGERY SHOWS A BREAK IN THE WEST BUT EXPECT CLOUDS TO
REGAIN MOMENTUM THIS AFTERNOON WITH SCATTERED SHOWERS DEVELOPING.
CURRENT SHOWERS ARE IN CENTRAL MONTANA AND WILL ARRIVE THIS EVENING
INTO TONIGHT.

UPDATE ISSUED AT 935 AM CDT THU MAY 16 2013

LATEST LOCAL RADAR SHOWS BANDS OF LIGHT TO MODERATE RAIN SHOWERS
MOVING FROM SOUTHWEST NORTH DAKOTA...INTO OUR SOUTH CENTRAL ZONES.
MULTIPLE UPSTREAM SHORTWAVES NOTED ON THE WATER VAPOR IMAGERY
WITH LARGE SCALE ASCENT/OMEGA CONTINUING FOR MOST OF THE
DAY...BUT ALSO SHIFTING FURTHER TO THE NORTHEAST AND INTO THE
JAMES RIVER BASIN. POPS OVERALL LOOK GOOD WITH ONLY MINOR
ADJUSTMENTS NECESSARY. REST OF FORECAST REMAINS ON TRACK.

UPDATE ISSUED AT 654 AM CDT THU MAY 16 2013

UPDATE TO REFINE POPS FOR MORNING RADAR TRENDS...OTHERWISE
PREVIOUS FORECAST IN GOOD SHAPE.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CDT THU MAY 16 2013

MAIN CONCERN THIS SHORT TERM PERIOD WILL BE THE CHANCE OF SHOWERS
AND THUNDERSTORMS.

CURRENTLY...SURFACE HIGH PRESSURE WAS OVER MANITOBA WITH LOW
PRESSURE OVER WYOMING. AT UPPER LEVELS...THE LEADING EDGE OF A
SERIES OF SHORTWAVE ENERGY IMPULSES WAS MOVING INTO SOUTHWESTERN
NORTH DAKOTA FROM THE WEST.

THE MODELS INDICATE THAT H850 WINDS SHOULD BE INCREASING FROM A
SOUTHEASTERLY DIRECTION ACROSS WESTERN SOUTH DAKOTA INTO THE
SOUTHWEST CORNER OF NORTH DAKOTA. MEANWHILE SOUTHWESTERLY WINDS AT
H700 AND FINALLY WESTERLY WINDS AROUND H500 WERE SETTING UP AN
OVERRUNNING PRECIPITATION SCENARIO THIS MORNING. THE STRONGER H850
WINDS WERE EVIDENT IN THAT A LINE OF ELEVATED CONVECTION SEEN ON
REGIONAL RADARS EXTENDED FROM NEAR BEACH TO BEULAH. THESE HIGH-BASED
SHOWERS AND ISOLATED THUNDERSHOWERS WERE MOVING EASTWARD WITH THE
UPPER LEVEL WIND FIELD.

THE MODELS ARE IN GOOD AGREEMENT IN BRINGING IN GOOD MOISTURE...WITH
INCREASING LOW LEVEL DEWPOINTS AS WELL AS H850 AND H700 MOISTURE
FIELDS...WITH OVERRUNNING PRECIPITATION CONTINUING INTO TONIGHT.
INSTABILITY IS MARGINAL AS BEST CAPE VALUES OF 200-400 J/KG REMAIN
ACROSS THE SOUTHWEST TODAY AND ACROSS THE WEST AND SOUTH TONIGHT.
THUS KEPT THE MENTION OF RAIN SHOWERS WITH ISOLATED THUNDERSTORMS
MAINLY SOUTH AND WEST DURING THE DAY TODAY AND EXPANDED THE MENTION
OF THUNDER A BIT NORTH AND EAST TONIGHT. WENT WITH HIGHS IN TE 60S
MOST AREAS IN THE WEST AND PARTS OF CENTRAL NORTH DAKOTA WITH FAIRLY
WIDESPREAD RAIN SHOWERS. THE RAIN AND BETTER MOISTURE WILL KEEP THE
FIRE DANGER IN THE LOW TO MEDIUM TODAY.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 352 AM CDT THU MAY 16 2013

THE MAIN FORECAST ISSUES THROUGH THE LONG TERM PERIOD ARE CONVECTIVE
TRENDS...AND POTENTIAL FOR HEAVY RAIN AND SOME SEVERE WEATHER.
SOUTHWEST FLOW WILL TRANSPORT ABUNDANT MOISTURE INTO THE NORTHERN
PLAINS FRIDAY AND SATURDAY. HAVE INCREASED POPS BOTH DAYS. THE FAR
SOUTHWEST IS STILL OUTLOOKED IN THE SPC 5 PERCENT RISK
AREA...COINCIDENT WITH THE MAIN INSTABILITY AXIS. SIGNIFICANT WARM
AIR ALOFT SHOULD LIMIT THE COVERAGE OF SEVERE STORMS. SPC HAS ALSO
INCLUDED THE FAR SOUTH/SOUTHEAST IN SLIGHT RISK FOR SATURDAY...NEAR
THE SURFACE BOUNDARY. PRECIPITABLE WATER VALUES AROUND 1.5 INCHES
ARE EXPECTED...AND THE GFS IS SUGGESTING SB CAPE AROUND 2000 J/KG.
WIDESPREAD 1 TO 2 INCH RAINFALL AMOUNTS ARE EXPECTED THROUGH
SATURDAY NIGHT. THE FAR SOUTHEAST IS NOT OUT OF THE WOODS CONCERNING
SEVERE WEATHER POTENTIAL SUNDAY. A LARGE UPPER LOW WILL MOVE INTO
THE REGION SUNDAY AND MONDAY...BRINGING ADDITIONAL MODERATE TO
LOCALLY HEAVY RAIN...WHICH WILL LIKELY LINGER THROUGH AT LEAST
TUESDAY. TOTAL RAINFALL AMOUNTS THROUGH THE ENTIRE PERIOD COULD
REACH 3 TO 4 INCHES OVER MUCH OF WESTERN AND CENTRAL NORTH DAKOTA.
RENEWED HYDRO CONCERNS ARE LIKELY...ESPECIALLY IN THE SOURIS AND
JAMES RIVER BASINS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 120 PM CDT THU MAY 16 2013

MOIST FLOW WILL CONTINUE THROUGH TAF PERIOD WITH SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS. THE MAIN AREA OF PRECIPITATION THURSDAY
AFTERNOON WILL OCCUR FROM KBIS TO KJMS WITH LESSER ACTIVITY FURTHER
NORTH AND WEST. HOWEVER MORE SHOWERS DEVELOPING OVER CENTRAL MONTANA
WILL PROPAGATE EAST AND ARRIVE IN THE WESTERN AERODROMES THURSDAY
NIGHT. MAINLY VFR CIGS/VSBYS...HOWEVER MVFR/IFR CIGS POSSIBLE IN THE
HEAVIER RAIN SHOWERS.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...KS
SHORT TERM...JV
LONG TERM...RP KINNEY
AVIATION...KS