000
FXUS63 KBIS 160016
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
716 PM CDT WED MAY 15 2013

.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 00Z TAFS THROUGH 24Z THURSDAY EVENING)
ISSUED AT 716 PM CDT WED MAY 15 2013

VFR CONDITIONS WILL PREVAIL OVER WESTERN AND CENTRAL NORTH DAKOTA
TONIGHT. A CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BEGIN TO
DEVELOP NEAR KDIK AFTER SUNRISE...THEN SLOWLY PUSH NORTH AND EAST
ACROSS NORTH DAKOTA THROUGH THURSDAY AFTERNOON. DUE TO THE EXPECTED
COVERAGE...ONLY INDICATED VCTS IN THE AFFECTED TAFS.

&&

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

&&

$$

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