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000
FXUS63 KBIS 160558
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1258 AM CDT THU MAY 16 2013

.UPDATE...
ISSUED AT 1258 AM CDT THU MAY 16 2013

ADJUSTED HOURLY TEMPERATURES AND DEWPOINTS WITH TEMPERATURE TREND A
TAD COOLER THAN EXPECTED...AND DEWPOINTS A BIT LOWER IN THE WEST.
EXPECT DEWPOINTS TO BEGIN RISING IN THE SOUTHWEST LATER TONIGHT AS
WINDS BECOME EAST/SOUTHEAST AND AS EXPECTED INCREASED LOWER LEVEL
CLOUDS AND POSSIBLE CONVECTION ARRIVES FROM THE SOUTHWEST.
OTHERWISE NO OTHER UPDATES WERE NEEDED TO THE ONGOING FORECAST FOR
THE OVERNIGHT TIME PERIOD.

UPDATE ISSUED AT 1003 PM CDT WED MAY 15 2013

ADJUSTED THE HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT
OBS/TRENDS. OTHERWISE...NO MAJOR UPDATES WERE REQUIRED TO THE
ONGOING FORECAST. THE FRESHENED UP PRODUCTS HAVE BEEN SENT.

UPDATE ISSUED AT 716 PM CDT WED MAY 15 2013

LAPS ANALYSIS CONTINUES TO INDICATE DECREASING CAPE ACROSS THE
REGION EARLY THIS EVENING. FURTHERMORE...RADAR TRENDS OF
SPRINKLES ARE DECREASING WITH THE LOSS OF DAYTIME HEATING. AS A
RESULT...UPDATED THE FORECAST TO REMOVE EVENING SPRINKLES. ALSO
MADE A FEW DOWNWARD ADJUSTMENTS TO OVERNIGHT LOWS AS WINDS SHOULD
BECOME LIGHT AND VARIABLE TONIGHT. OTHERWISE...THE REMAINING
WEATHER ELEMENTS ARE IN GOOD SHAPE. THE UPDATED GRIDDED AND TEXT
PRODUCTS HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 250 PM CDT WED MAY 15 2013

MAIN CONCERN THIS SHORT TERM PERIOD WILL BE THE CHANCE OF
THUNDERSTORMS LATE TONIGHT AND THURSDAY. MODELS ARE IN GOOD
AGREEMENT IN BRINGING IN GOOD MOISTURE...WITH OVERRUNNING
PRECIPITATION OVER A WARM FRONTAL BOUNDARY DEVELOPING ACROSS
NEBRASKA AND SOUTH DAKOTA ON THURSDAY. INSTABILITY IS MARGINAL AS
BEST CAPE VALUES REMAIN ACROSS THE SOUTH AND WEST. SO BELIEVE
THERE WILL BE RAIN SHOWERS WITH ISOLATED THUNDERSTORMS MAINLY
SOUTH AND WEST ON THURSDAY. WITH FAIRLY WIDESPREAD RAIN SHOWERS
ACROSS WEST AND CENTRAL...LOWERED THE HIGH TEMPERATURES INTO THE
60S FOR THE MOST PART. THE RAIN AND BETTER MOISTURE WILL KEEP THE
FIRE DANGER IN THE LOW TO MEDIUM ON THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 250 CDT WED MAY 15 2013

THE FOCUS IN THE LONG TERM WILL BE ON PRECIPITATION SUNDAY INTO
EARLY NEXT WEEK.

MODEL AGREEMENT ON THE DEVELOPING RIDGE OVER THE CENTRAL CONUS AND
TROUGH OVER THE WESTERN CONUS CONTINUES THURSDAY INTO SATURDAY.
DURING THIS TIME FRAME SOUTHWEST FLOW ALOFT WILL DOMINATE AND SHORT
WAVE ENERGY WITH AMPLE MOISTURE WILL PROVIDE NUMEROUS CHANCES FOR
RAINFALL THURSDAY INTO THE WEEKEND. UNCERTAINTY IN THE LONG TERM
BEGINS LATE SUNDAY INTO EARLY NEXT WEEK...WITH THE PLACEMENT OF THE
TROUGH AND CUT OFF UPPER LEVEL LOW AND HOW LONG THESE FEATURES
LINGER OVER THE REGION. GFS AND GEM GLOBAL 12 UTC RUNS PLACE THE CUT
OFF LOW OVER THE DAKOTAS AND KEEP IT OVER THE AREA INTO TUESDAY.
THIS SOLUTION HAS COMMA HEAD PRECIPITATION OVER WESTERN AND CENTRAL
NORTH DAKOTA INTO EARLY NEXT WEEK. THE ECMWF ON THE OTHER HAND
PLACES THE CUT OFF LOW FURTHER EAST OVER THE DAKOTA MINNESOTA
BORDER...WHICH WOULD KEEP COMMA HEAD PRECIPITATION EAST OF CENTRAL
NORTH DAKOTA. THIS IS LESS MODEL VARIANCE THAN THE PAST FEW DAYS
HAVE SHOWN WITH THE CUT OFF LOW PLACEMENT...HOWEVER THE SLIGHTEST
SHIFT WILL PLAY A LARGE ROLE IN WHETHER OR NOT CENTRAL AND
POSSIBLY WESTERN NORTH DAKOTA HAVE A TROWAL SET UP OVER HEAD
PROVIDING RAINFALL EARLY NEXT WEEK. REGARDLESS OF WHETHER OR NOT A
TROWAL SETS UP OVER CENTRAL AND WESTERN NORTH DAKOTA INTO EARLY
NEXT WEEK...I WOULD EXPECT SEASONABLY COOL...DAMP...AND CLOUDY
CONDITIONS.

RAINFALL TOTALS THROUGH THE WEEKEND ARE GENERALLY IN THE INCH TO
INCH AND HALF RANGE. THIS WOULD BE MORE THAN ENOUGH TO GREEN UP
CENTRAL AND WESTERN NORTH DAKOTA...MINIMIZING FIRE WEATHER ISSUES.
AS FOR RAINFALL TOTALS INTO EARLY NEXT WEEK IT SEEMS WPC IS RELYING
ON THE ECMWF AND ESSENTIALLY ENDING ANY REAL ACCUMULATIONS AFTER
SUNDAY FOR BOTH CENTRAL AND WESTERN NORTH DAKOTA...HOWEVER THIS WILL BE
MONITORED CLOSELY THROUGH THE WEEK.

THIS SET UP WILL PROVIDE CHANCES FOR SEVERE WEATHER. THURSDAY INTO
SATURDAY. MODELS HAVE DECREASED CAPE VALUES THURSDAY NIGHT AND
FRIDAY OVER THE LAST FEW DAYS...HOWEVER BULK SHEAR VALUES STILL IN
THE 40 TO 50 KT RANGE MAY PROVIDE A CHANCE FOR THUNDERSTORMS AND
SEVERE WEATHER. THE BEST OPPORTUNITY FOR SEVERE WEATHER LOOKS TO BE
SATURDAY ACROSS SOUTH CENTRAL AND SOUTHWESTERN NORTH DAKOTA WITH
CAPE VALUES AROUND 1000 TO 3000 J/KG AND DEEP LAYER BULK SHEAR
AROUND 50 KTS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1258 AM CDT THU MAY 16 2013

SURFACE HIGH OVER MANITOBA AND SURFACE LOW WAS OVER WYOMING. WINDS
WERE GENERALLY LIGHT AND VARIABLE OVER NORTH DAKOTA BETWEEN THESE
TWO SURFACE PRESSURE SYSTEMS. LATER TONIGHT AS THE LOW DEVELOPS
FARTHER EAST...WINDS SHOULD BECOME EAST/SOUTHEAST AT TAF SITES.
LEADING EDGE OF UPPER LEVEL ENERGY EXPECTED TO BE APPROACHING KDIK
AFTER 11Z...AND MORE LIKELY AFT 15Z. THIS CONVECTION WITH MVFR
CIGS EXPECTED TO SPREAD NORTH AND EAST LATER THURSDAY
MORNING...WITH SHOWERS AND THUNDERSHOWERS MORE LIKELY AT KBIS AND
KISN AROUND/AFT 18Z. AFTER 00Z CONVECTION MORE LIKELY AT NORTHERN
TAF SITES KISN/KMOT.

&&

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

$$

UPDATE...JV
SHORT TERM...WAA
LONG TERM...MM/KS
AVIATION...JV