Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 161716
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1216 PM CDT THU APR 16 2015

.UPDATE...
ISSUED AT 1215 PM CDT THU APR 16 2015

OBVIOUSLY A VERY TRICKY WEATHER PATTERN WE ARE IN FOR THE NEXT FEW
DAYS AS FAR AS TRYING TO "PINPOINT" PRECIP CHANCES/COVERAGE MORE
THAN A FEW HOURS IN ADVANCE. THE FIRST ROUND OF MODEST...MUCH-
NEEDED RAINFALL OF MAINLY 0.20-0.60-INCH THAT TARGETED MAINLY THE
WESTERN CWA OVERNIGHT HAS FADED AWAY/LIFTED NORTH...LEAVING IN ITS
WAKE A SIZABLE AREA OF ONLY SPOTTY LIGHT SHOWERS/PATCHY DRIZZLE
AND EVEN SOME LEGITIMATE MAINLY LIGHT FOG MAINLY OVER WEST-
CENTRAL ZONES.

GENERALLY...HERE ARE THE EXPECTATIONS FOR THE NEXT 12 HOURS OR
SO:

BASED ON LATEST TRENDS IN SHORT TERM MODELS SUCH AS RAP/HRRR
AND 4KM WRF...THE LACK OF LARGE-SCALE FORCING AND CURRENT LIMITED
INSTABILITY...THE MAJORITY OF THE CWA SHOULD MAKE IT THROUGH THE
MID-LATE AFTERNOON HOURS WITH NOTHING MORE THAN A PASSING LIGHT
SHOWER/SPOTTY DRIZZLE. HOWEVER...AS THE NEXT BATCH OF MODEST MID
LEVEL SHORTWAVE ENERGY KICKS NORTHEAST OUT OF THE NORTHEAST
PERIPHERY OF THE PARENT CLOSED LOW CENTERED WELL-SOUTHWEST NEAR
THE 4-CORNERS...GRADUAL DESTABILIZATION SHOULD LEAD TO INCREASING
COVERAGE OF SHOWERS/THUNDERSTORMS THROUGH THE LATE AFTERNOON AND
ESPECIALLY EVENING. INITIALLY...THE GREATEST COVERAGE AND THREAT
FOR STRONG STORMS/ISOLATED SEVERE WEATHER LOCALLY SHOULD TARGET
THE SOUTHWEST 1/3 OF THE CWA...BUT ESPECIALLY KS ZONES.
HOWEVER...THE "MAIN SHOW" FOR A GREATER RISK OF SEVERE STORMS ON
THE REGIONAL SCALE SHOULD LARGELY FOCUS JUST OUTSIDE THE CWA TO
THE SOUTH AND WEST WITHIN WEST-CENTRAL/SOUTHWEST KS...WHERE THE
PRIMARY SPC SLIGHT/ENHANCED RISK AREAS ARE FOCUSED. WITH
INSTABILITY EVEN WITHIN SOUTHERN PORTIONS OF THE LOCAL AREA (BOTH
LOW-LEVEL AND ELEVATED) CURRENTLY EXPECTED TO ONLY REACH UP TO
AROUND 1000 J/KG IN THE PRESENCE OF DEEP LAYER SHEAR AROUND
30-40KT...COULD EASILY SEE A MIX OF MULTICELL AND SEMI-ORGANIZED
SUPERCELL STRUCTURES...WITH LOW-END SEVERE HAIL/WIND CLEARLY THE
MAIN THREATS. WITH LOW-LEVEL EASTERLY FLOW...FAIRLY LOW LCL
HEIGHTS AND VARIOUS MESOSCALE INTERACTIONS POSSIBLE...AT LEAST A
BRIEF LATE AFTERNOON-EVENING TORNADO IS NOT COMPLETELY OUT OF THE
QUESTION IN SOUTHERN ZONES...BUT AGREE WITH SPC THAT THIS
PROBABILITY IS QUITE LIMITED/MAINLY 2 PERCENT AT MOST...AND THUS
WILL REFRAIN FROM EVEN MENTIONING A TORNADO RISK IN THE HAZARDOUS
WEATHER OUTLOOK UNLESS LATER TRENDS SUGGEST OTHERWISE. WHILE THE
MAIN OPPORTUNITY FOR POSSIBLE SEVERE STORMS WILL LIKELY FOCUS
DURING THE TYPICAL 4PM- MIDNIGHT TIME FRAME...AT LEAST A FEW
STRONGER STORMS COULD LINGER /RE-DEVELOP WELL INTO THE
NIGHT...POSSIBLY IN 1 OR MORE ROUNDS. OF COURSE...TIMING THESE
INDIVIDUAL ROUNDS OF CONVECTION AND THE ASSOCIATED BREAKS IN
BETWEEN WILL BE VERY DIFFICULT. ON A POSITIVE NOTE...THINK A
DECENT CHUNK OF THE CWA WILL PROBABLY SEE NEW RAINFALL AMOUNTS OF
0.50-1.00" (AND LOCALLY HIGHER) BY SUNRISE FRIDAY...ESPECIALLY
SOUTHERN/WESTERN ZONES.

TEMP-WISE TODAY...WHILE MOSTLY CLOUDY SKIES SHOULD REMAIN IN
PLACE MOST AREAS...THERE HAVE ALREADY BEEN DECENT BREAKS IN
OVERCAST IN SOUTHWESTERN ZONES...WHICH HAVE THE BEST CHANCE OF
POSSIBLY BREACHING 70. MEANWHILE...MOST OF THE CWA (ESPECIALLY IN
NEBRASKA) IS STILL EXPECTED TO TOP OUT SOMEWHERE IN THE
60S...ALBEIT BARELY-SO IN SOME SPOTS. MORE TO COME WITH MAIN
AFTERNOON DISCUSSION...

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CDT THU APR 16 2015

RADAR SHOWS SHOWERS AND THUNDERSTORMS MOVING NORTH/NORTHEAST WITH
DEVELOPMENT ON THE SOUTH END OF THE MAIN CLUSTER OF THUNDERSTORMS.
SURFACE ANALYSIS SHOWS A LOW PRESSURE SYSTEM ACROSS WESTERN KANSAS
WITH A COLD FRONT EXTENDING TO THE NORTH ACROSS NEBRASKA.

AN UPPER LEVEL LOW IN THE IN THE FOUR CORNERS REGION WILL DRIFT
TOWARD THE EAST TODAY AND TONIGHT. IN ADVANCE OF THE UPPER LOW A FEW
WAVES WILL MOVE ACROSS THE AREA THROUGH TONIGHT. THE NAM AND GFS
BOTH SPREAD THE PRECIPITATION ACROSS THE FORECAST AREA THROUGH THE
MORNING HOURS AS THE FIRST OF THE WAVES MOVE THROUGH THE FORECAST
AREA. THE RAP AND THE 4KM WRF BOTH INDICATE THIS INITIAL GROUP OF
THUNDERSTORMS WILL MOVE THROUGH AND ALTHOUGH THERE MAY BE SOME
ISOLATED THUNDERSTORMS AROUND...THERE COULD BE A BREAK THIS MORNING.
HAVE KEPT POPS ACROSS THE AREA...BUT DID LOWER THEM A BIT THIS
MORNING.

THE NEXT WAVE WILL MOVE INTO THE AREA THIS AFTERNOON AND EVENING.
THUNDERSTORMS SHOULD DEVELOP IN WESTERN KANSAS AND SPREAD INTO THE
AREA DURING THE AFTERNOON. LATE AFTERNOON INTO THE EARLY EVENING THE
MUCAPE INCREASES TO NEARLY 2500 J/KG MAINLY ACROSS KANSAS. THIS IS
THE AREA WITH THE BEST CHANCE FOR SOME SEVERE WEATHER. ANOTHER UPPER
LEVEL WAVE PUSHES INTO THE AREA LATE TONIGHT. SHOWERS AND
THUNDERSTORMS ARE EXPECTED ACROSS THE AREA LATE TONIGHT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 412 AM CDT THU APR 16 2015

A PAIR OF UPPER LEVEL LOWS FORECAST TO TRACK ACROSS THE SOUTHERN
HALF OF THE COUNTRY WILL BRING SOME SIGNIFICANT CHANCES FOR
BENEFICIAL RAINFALL TO THE REGION OVER THE NEXT WEEK OR SO. THE
FIRST OF THESE LOW PRESSURE SYSTEMS IS CURRENTLY SPINNING ACROSS THE
DESERT SOUTHWEST...AND ALREADY HAVING AN IMPACT ON THE LOCAL
WEATHER. WITH THIS LOW CUT OFF FROM THE MAIN UPPER LEVEL FLOW ACROSS
CANADA...EXPECT VERY SLOW PROGRESSION TOWARDS THE EAST TO RESULT IN
MULTIPLE DAYS OF UNSETTLED WEATHER ACROSS THE REGION.

WITH MOIST SOUTHERLY FLOW AHEAD OF THIS SYSTEM...DEWPOINTS HAVE
SURGED INTO THE 50S ACROSS MUCH OF THE LOCAL AREA AND EXPECT THE
ASSOCIATED INSTABILITY TO HELP AID IN THE FORMATION OF THUNDERSTORMS
BOTH FRIDAY AND SATURDAY. THAT SAID...WITH MUCH BETTER SHEAR TO WORK
WITH ON FRIDAY AFTERNOON/EVENING...THIS APPEARS TO BE THE BEST SHOT
FOR MORE WIDESPREAD STRONG AND POTENTIALLY SEVERE STORMS ACROSS THE
REGION...AND NOT SURPRISINGLY ROUGHLY THE SOUTHERN HALF OF THE
FORECAST AREA IS NOW OUTLOOKED BY SPC. IF REALIZED...THE MAIN
HAZARDS ARE LIKELY TO BE LARGE HAIL AND STRONG WIND GUSTS.

WHILE STILL NOT OUT OF THE QUESTION FOR SATURDAY...ADDITIONAL STRONG
TO MARGINALLY SEVERE THUNDERSTORMS WILL BE POSSIBLE DURING THE
AFTERNOON AND EVENING HOURS...BUT DUE TO DIMINISHED SHEAR
VALUES...THINK THE COVERAGE OF THESE STRONGER STORMS WILL BE MUCH
MORE LIMITED. EVEN SO...WIDESPREAD BENEFICIAL RAINFALL IS
ANTICIPATED FOR THE ENTIRE REGION BOTH DAYS...WITH STORM TOTAL
PRECIPITATION AMOUNTS OVER 2 INCHES EXPECTED TO BE FAIRLY WIDESPREAD
BY THE TIME THE RAINFALL ENDS AND THE RESPONSIBLE LOW PRESSURE
SYSTEM TRACKS EASTWARDS SUNDAY AFTERNOON.

THIS LOW PRESSURE SYSTEM WILL BE SHIFTED EASTWARD BY A FAIRLY STRONG
COLD FRONT FORECAST TO DROP SOUTH ACROSS THE LOCAL AREA SUNDAY. THIS
COLD FRONT WILL BRING SIGNIFICANTLY COOLER TEMPERATURES TO START THE
NEW WORK WEEK WITH POTENTIALLY SOME NEAR FREEZING TEMPERATURES
CURRENTLY FORECAST FOR BOTH MONDAY AND TUESDAY MORNINGS. WHILE
ACTUAL FROST MAY NOT DEVELOP EITHER DAY...THESE COOLER TEMPERATURES
WILL BE SOMETHING TO MONITOR AS SENSITIVE VEGETATION MAY BE
IMPACTED. ADDITIONALLY...WITH STRONG NORTHWESTERLY WINDS BEHIND THIS
FRONT AND DRIER AIR ADVECTING IN FROM THE NORTH...COULD EVENTUALLY
SEE SOME NEAR CRITICAL FIRE WEATHER CONDITIONS REALIZED ACROSS
ROUGHLY THE NORTHWESTERN HALF OF THE LOCAL AREA. BECAUSE BOTH OF
THESE POTENTIAL HAZARDS ARE STILL SEVERAL DAYS OUT AND
MARGINAL...OPTED NOT TO MENTION EITHER OF THESE IN THE MORNING HWO.

THEREAFTER...RAINFALL CHANCES WILL INCREASE MIDWEEK AS ANOTHER UPPER
LEVEL LOW MOVES INTO THE DESERT SOUTHWEST AND MOISTURE INCREASES
ACROSS THE REGION.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1215 PM CDT THU APR 16 2015

THIS WILL A RATHER CHALLENGING PERIOD REGARDING CEILING/VISIBILITY
TRENDS AND ALSO SHOWER/THUNDERSTORM COVERAGE...AND MODIFICATIONS
TO THESE ELEMENTS IN UPCOMING TAF ISSUANCES BOTH ROUTINE ISSUANCE
AND AMENDMENTS ARE LIKELY. BEAR WITH US...

IN GENERAL HOWEVER...AM EXPECTING CURRENT SUB-VFR CEILINGS AND
PATCHY DRIZZLE RIGHT AWAY EARLY THIS AFTERNOON TO LIFT INTO LOW-
END VFR AT SOME POINT THIS AFTERNOON. WHILE AN MVFR/IFR CEILING
CANNOT BE RULED OUT RETURNING AT SOME POINT THIS
EVENING/TONIGHT...WILL HOLD OFF ON THIS MENTION UNTIL THE LATTER
HALF OF THE PERIOD FOR NOW. AS FOR SHOWER/THUNDERSTORM
CHANCES...WHILE PRECIPITATION IS LIKELY ESPECIALLY TONIGHT AT THE
TERMINALS...DO NOT YET HAVE THE CONFIDENCE TO ADVERTISE PREVAILING
SHOWERS/THUNDERSTORMS DURING ANY GIVEN TIME FRAME...AND THUS WILL
CONTINUE TO CARRY EITHER A VICINITY SHOWER (VCSH)/VICINITY
THUNDERSTORM (VCTS) MENTION UNTIL SOMETHING TRULY SHOWS ITS HAND.
FORTUNATELY...SURFACE WIND TRENDS SEEM REASONABLY STRAIGHTFORWARD
(OUTSIDE OF ANY CONVECTIVE ENHANCEMENT/MODIFICATION OF
COURSE)...WITH A GENERALLY EASTERLY DIRECTION PRIMARILY UNDER 12KT
IN PLACE THE MAJORITY OF THE TIME.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

UPDATE...PFANNKUCH
SHORT TERM...JCB
LONG TERM...ROSSI
AVIATION...PFANNKUCH


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