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FXUS63 KBIS 121805
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
105 PM CDT SUN MAY 12 2013

.UPDATE...
ISSUED AT 101 PM CDT SUN MAY 12 2013

CURRENT TRENDS LOOKING GOOD FOR TODAY. SUNNY SKIES WITH A WARMING
SOUTHEAST WIND. CONTINUING TO EVALUATE FORE WEATHER THREATS FOR
MONDAY AND TUESDAY.

UPDATE ISSUED AT 858 AM CDT SUN MAY 12 2013

SUNDAY MORNING...HIGH PRESSURE WAS CENTERED OVER SOUTHWEST
MINNESOTA. A WARM FRONT EXTENDED ACROSS EASTERN MONTANA. THE WARM
FRONT IS FORECAST TO MOVE EAST TODAY AND TONIGHT AND WILL BE
RESPONSIBLE FOR SOME WIDELY SCATTERED SHOWERS TONIGHT ACROSS
THE NORTH AND EAST. SO FAR THIS MORNING...SKIES WERE MOSTLY CLEAR
AND THERE WAS LITTLE CLOUDINESS OVER THE STATE. SOME HIGH CLOUDS
WEE OVER MONTANA SO MOSTLY SUNNY LOOKS GOOD FOR THE MORNING AND
EARLY AFTERNOON...FOLLOWED BY SOME INCREASE IN CLOUDS NORTHWEST
LATE THIS AFTERNOON. WITH THIS SCENARIO IN MIND...THE CURRENT
FORECAST IS TRENDING WELL FOR TODAY.

UPDATE ISSUED AT 647 AM CDT SUN MAY 12 2013

A COLD START TO THIS SUNDAY MORNING. CURRENT TEMPERATURES ARE
RANGING FROM THE LOW TO MID 20S EAST AND CENTRAL...TO THE MID 30S
OUT WEST AS SOUTHERLY RETURN FLOW HAS BEGUN. NO CHANGES TO THE
CURRENT FORECAST EXCEPT A SLIGHT LOWERING OF CLOUD COVER.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT SUN MAY 12 2013

THE MAIN FEATURE OF THIS SHORT TERM FORECAST PERIOD WILL BE THE
SURFACE HIGH PRESSURE AXIS CURRENTLY CENTERED OVER THE RED RIVER
VALLEY...FROM LAKE WINNIPEG SOUTHWARD INTO THE EASTERN
DAKOTAS/MINNESOTA TO NEBRASKA/IOWA BORDER. MEANWHILE LOW PRESSURE IN
THE LEE OF THE ROCKIES FROM NORTHERN ALBERTA TO WYOMING IS FORECAST
TO CONTINUE DEVELOPING. THE LIGHT WINDS IN THE EASTERN HALF OF THE
STATE WILL BECOME SOUTHEAST DURING THE DAY AS THE HIGH MOVES EAST.
THE DRY HIGH PRESSURE RIDGE WAS ADVECTING DEWPOINTS OF 10 TO 20 INTO
WESTERN AND SOUTH CENTRAL NORTH DAKOTA.

THE MODELS SUGGEST THE SOUTHEAST WINDS TODAY WILL EVENTUALLY BRING
IN SOME DEWPOINTS IN THE 20S EAST TO LOWER 30S WEST DURING THE
AFTERNOON. LOOKING AT HIGHS FROM THE 60S IN THE TURTLE MOUNTAINS AND
JAMES RIVER BASINS TO THE UPPER 70S SOUTHWEST. MINIMUM RELATIVE
HUMIDITY SHOULD BE IN THE UPPER TEENS TO 25 PERCENT ACROSS WESTERN
AND CENTRAL NORTH DAKOTA. SOUTHEAST TO SOUTH WINDS ARE EXPECTED TO
RANGE FROM 5 TO 15 MPH. THE LIGHT WINDS WILL KEEP FIRE DANGER IN THE
MEDIUM CATEGORY OVER CENTRAL NORTH DAKOTA TO THE HIGH CATEGORY WEST
ACROSS THE STATE.

SOUTH WINDS AGAIN TONIGHT WILL KEEP LOWS TONIGHT ABOVE FREEZING IN
THE 40 TO LOWER 50S RANGE. LATE TONIGHT A WEAK UPPER LEVEL SHORTWAVE
WILL MOVE SOUTHEAST ACROSS THE REGION...AND IN RESPONSE THE SURFACE
TROUGH/FRONT IN THE LEE OF THE ROCKIES WILL MOVE EASTWARD INTO
WESTERN NORTH DAKOTA. THIS FEATURE WILL CREATE ENOUGH INSTABILITY
FOR THE MENTION OF A SLIGHT/SMALL CHANCE OF SHOWERS.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 350 AM CDT SUN MAY 12 2013

THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL BE FIRE
WEATHER ISSUES MONDAY AND TUESDAY...THEN SHOWER AND THUNDERSTORM
CHANCES TOWARD THE END OF THE WORK WEEK. SEE THE FIRE WEATHER
SECTION FOR MORE DETAILED FIRE WEATHER DISCUSSION.

ON MONDAY...A WARM FRONT WILL MOVE FROM WESTERN INTO EASTERN NORTH
DAKOTA...WITH STRONG THERMAL RIDGING DEVELOPING OVER THE AREA UNDER
A BUILDING UPPER LEVEL RIDGE. NORTHWEST WINDS OF 20 TO 25 MPH BEHIND
THE WARM FRONT...COMBINED WITH VERY WARM TEMPERATURES IN THE 80S TO
LOWER 90S WILL PRODUCE VERY HIGH FIRE DANGER ACROSS ALL BUT THE FAR
NORTHERN AND EASTERN COUNTIES. FIRE WEATHER WATCH REMAINS IN EFFECT
FROM MID MORNING TO MID EVENING FOR AREAS ALONG AND WEST OF HIGHWAY
83. A STRONG SHORTWAVE TRACKS ACROSS THE NORTHERN ROCKIES DURING
THIS PERIOD AND PUSHES INTO THE NORTHERN PLAINS BY MONDAY EVENING. A
STRONG LOW LEVEL JET DEVELOPS AND MOVE EAST ACROSS THE FORECAST AREA
MONDAY NIGHT AHEAD OF THE SYSTEM AND WILL INCREASE INSTABILITY AND
CONGRUENT WITH THE MID LEVEL FORCING AHEAD OF THE WAVE...SHOWER AND
THUNDERSTORMS ARE POSSIBLE...MAINLY ACROSS THE NORTHERN HALF OF THE
CWA MONDAY NIGHT.

ON TUESDAY...THE WAVE...AND ASSOCIATED SURFACE LOW TRACKS ACROSS THE
LOCAL AREA. THERE AREA SIGNIFICANT MODEL DIFFERENCES...WITH THE GFS
BEING THE SLOWEST AND DEEPEST SOLUTION...TRACKING A CLOSED UPPER LOW
ALONG THE INTERNATIONAL BORDER. THE ECMWF IS THE WEAKEST KEEPING AN
OPEN WAVE WELL NORTH OF THE GFS POSITION. THE GLOBAL GEM IS A
COMPROMISE SOLUTION...BUT TRACKS THE UPPER LOW SIMILAR TO THE GFS.
THE RESULTING DIFFERENCES COULD PLAY A BIG ROLE IN FIRE AND WIND
HIGHLIGHTS FOR TUESDAY. AT THIS TIME IT LOOKS LIKE A WINDY DAY AND
ALTHOUGH MINIMUM HUMIDITIES ARE HIGHER THAN MONDAY...THE INCREASED
WINDS WILL TRUMP THE HIGHER HUMIDITIES. THUS WE HAVE ISSUED ANOTHER
FIRE WEATHER WATCH FOR LATE TUESDAY MORNING THROUGH EARLY TUESDAY
EVENING. WIND ADVISORY CRITERIA LOOKS TO BE A GOOD BET ACROSS THE
AREA. A 00 UTC SUNDAY GFS SOLUTION WOULD RESULT IN POSSIBLE HIGH
WIND WARNING CRITERIA OVER THE WEST AND PORTIONS OF THE CENTRAL. AT
THIS TIME...UTILIZED A BLEND OF THE HIGHER GFS WINDS WITH THE THE
CONSENSUS BLEND...TO HEDGE TOWARD HIGHER WINDS ON TUESDAY.

A QUASI-ZONAL FLOW TAKES SHAPE WEDNESDAY AND THURSDAY WITH
SEASONABLE TEMPERATURES. MAINLY DRY CONDITIONS ARE EXPECTED
WEDNESDAY. THERE WILL BE A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS
ON THURSDAY AS A WEAK SHORTWAVE MOVES THROUGH THE ZONAL FLOW.

THURSDAY NIGHT THROUGH SATURDAY BECOME MORE UNSETTLED AS AN UPPER
LEVEL TROUGH MOVES FROM THE WESTERN U.S. INTO THE NORTHERN AND
CENTRAL PLAINS. SIGNIFICANT MODEL DIFFERENCES EXIST AT THIS TIME IN
THE EVOLUTION OF THIS TROUGH AS IT APPROACHES THE REGION.
HOWEVER...AN INCREASE IN SHOWER AND THUNDERSTORMS FRIDAY AND
SATURDAY SEEMS QUITE REASONABLE. UTILIZED A MODEL BLEND WITH
PERSISTENCE HERE...RESULTING IN MAINLY HIGH CHANCE POPS FRIDAY INTO
SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 101 PM CDT SUN MAY 12 2013

AT 1 PM CDT...HIGH PRESSURE ACROSS MINNESOTA/IOWA MOVING EAST. WARM
FRONT IN MONTANA IS FORECAST TO MOVE EAST THIS AFTERNOON AND
TONIGHT. THE WARM FRONT WILL BE THE FOCUS FOR SCATTERED SHOWERS
NORTHWEST AND CENTRAL LATE THIS EVENING AND OVERNIGHT. THEN A COLD
FRONT WILL FOLLOW ON MONDAY BRINGING GUSTY WEST WINDS. VFR AT ALL
TAF SITES THROUGH THE 18Z TAF PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 350 AM CDT SUN MAY 12 2013

VERY WARM TEMPERATURES ON MONDAY...COMBINED WITH LOW HUMIDITIES IN
THE TEENS TO LOWER 20S AND BREEZY WEST TO NORTHWEST WINDS WILL YIELD
HIGH TO VERY HIGH FIRE DANGER OVER WESTERN AND CENTRAL NORTH DAKOTA.
00 UTC SUN GFS BUFR SOUNDINGS INDICATE NEARLY ADIABATIC LAPSE RATES
TO 750 MB MONDAY AFTERNOON WITH THE POTENTIAL FOR 15-25KT WINDS TO
MIX DOWN TO THE SURFACE. A FIRE WEATHER WATCH REMAINS IN EFFECT. AT
THIS TIME THIS LOOKS TO BE A MARGINAL EVENT AS THE STRONGEST WINDS
PROGRESS WEST TO EAST DURING THE DAY. THUS BY THE TIME WE ARE
ACHIEVING OUR MINIMUM HUMIDITIES ACROSS THE WEST...WINDS SHOULD BE
ON THE DECLINE. AS THE STRONGER WINDS TRANSLATE INTO CENTRAL NORTH
DAKOTA DURING THE AFTERNOON...THEY WILL ENCOUNTER HIGHER MINIMUM
HUMIDITIES IN THE RANGE OF 20 TO 25 PERCENT ALONG THE HIGHWAY 83
CORRIDOR...AND EVEN HIGHER AS YOU MOVE EAST. WILL NEED TO MONITOR AS
WE COULD REASONABLY SEE A PARING DOWN OF THE WATCH AREA...LIMITING
IT TO MINIMUM HUMIDITIES 20 PERCENT OR LESS...WITH CURRENT FORECAST
WINDS NOT QUITE HIGH ENOUGH TO REACH RED FLAG WARNING (RFW)
CRITERIA WITH HUMIDITIES ABOVE 20 PERCENT. BUT IF WINDS ARE A
LITTLE HIGHER...WE WOULD REALIZE RFW CRITERIA ACROSS THE WATCH
AREA...THUS NO CHANGES AT THIS TIME.

ON TUESDAY...A COLD FRONT WILL MOVE THROUGH THE AREA BRINGING EVEN
STRONGER WEST TO NORTHWEST WINDS. CURRENTLY THE GFS SOLUTION IS THE
STRONGEST OF THE DETERMINISTIC MODELS...AND GFS IS TYPICALLY ON THE
HIGH SIDE FOR WINDS. BUT 00 UTC SUNDAY BUFR SOUNDINGS INDICATE A
VERY WINDY DAY WITH WIND ADVISORY CRITERIA WINDS...AND POSSIBLY HIGH
WIND WARNING WINDS. SLIGHTLY COOLER TEMPERATURES AND INCREASED CLOUD
COVER WILL RESULT IN HUMIDITIES NOT AS LOW AS MONDAY...MAINLY 20 TO
30 PERCENT...EXCEPT 15 TO 20 PERCENT FAR SOUTHWEST AND SOUTH
CENTRAL. BUT WITH THE STRONGER WINDS...FIRE DANGER WILL REACH THE
EXTREME CATEGORY IN THE LOWER HUMIDITIES ACROSS THE SOUTHWEST AND
SOUTH CENTRAL...WITH VERY HIGH FIRE DANGER ACROSS THE REMAINDER OF
THE LOCAL AREA. DUE TO THE POSSIBILITY OF VERY STRONG
WINDS...COMBINED WITH THE ABUNDANT DRY VEGETATION...WE OPTED TO
ISSUE A FIRE WEATHER WATCH FOR LATE TUESDAY MORNING THROUGH EARLY
TUESDAY EVENING ACROSS ALL BUT THE FAR NORTHERN TIER COUNTIES. IF
CURRENT TRENDS HOLD WE WILL ALSO HAVE REGULAR WIND HIGHLIGHTS...A
WIND ADVISORY AND POSSIBLY A HIGH WIND WARNING ACROSS AT LEAST A
PORTION OF THE AREA.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
FOR NDZ001>003-009>011-017>021-031>035-040>046.

FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NDZ009>013-017>023-025-031>037-040>048-050-051.

&&

$$

UPDATE...WAA
SHORT TERM...JV
LONG TERM...TWH
AVIATION...WAA
FIRE WEATHER...TWH